TW202300609A - Surface protective sheet and treatment method - Google Patents

Abstract

Provided is a surface protective sheet in which, even when used in a state of being attached to an object to be protected in a process including a step for treating the object to be protected in a liquid, peeling from an end part as a result of an external force, such as vibration, during said process is unlikely to occur, and in which, at the time of peeling, peeling can be performed without causing damage or deformation in the object to be protected. The provided surface protective sheet has a flexural rigidity value at 25 DEG C within the range of 1.0*10<SP>-6</SP> to 1.0*10<SP>-2</SP> Pa.m3. In addition, the abovementioned surface protective sheet has a water peeling force FW0 of 1.0 N/20 mm or less.

Description

Surface protection sheet and treatment method

The invention relates to a surface protection sheet and a treatment method. This application claims priority based on Japanese Patent Application No. 2021-52064 filed on March 25, 2021 and Japanese Patent Application No. 2021-151206 filed on September 16, 2021, and these applications The entire content is incorporated into this specification as a reference.

There is known a technique of attaching a protective sheet (adhesive sheet) to the surface for the purpose of preventing damage (scratch, contamination, corrosion, etc.) on the surface when processing or transporting various articles. For example, in various treatments such as chemical treatment of glass, semiconductor wafers, metal plates, etc., or physical treatment such as cutting or grinding using chemical liquid (etching solution), by attaching a surface protection sheet to the object to be protected The non-treated surface, so that the non-treated surface is protected. Patent Document 1 can be cited as a prior art document related to a protective sheet for chemical liquid treatment. Furthermore, Patent Document 2 is a prior art document related to a water-releasable adhesive sheet. [Prior Art Literature] [Patent Document]

Patent Document 1: Japanese Patent Application Publication No. 2015-193688 Patent Document 2: Japanese Patent Application Publication No. 2020-23656

[Problem to be solved by the invention]

After achieving the purpose of protection, the surface protection sheet is removed from the adherend (object to be protected) at an appropriate point. Therefore, the surface protection sheet is required to have adhesiveness required for protection of the object to be protected during the protection period such as chemical solution treatment, and easy peelability when peeling and removing from the object to be protected. If the peeling force against the object to be protected is large, for example, when the thickness of the object to be protected is thin, when the surface protection sheet is peeled and removed from the object to be protected, the object may be damaged due to the peeling force. Risk of damage or deformation.

In recent years, the miniaturization or thinning of electronic devices (such as portable electronic devices) such as smartphones, tablet computers, and various wearable devices has been continuously promoted. Accordingly, semiconductor components used in these electronic devices, or Optical components such as glass also tend to be thinner. Therefore, the surface protection sheet used to protect the above-mentioned members also needs to have easy peelability that does not cause damage or deformation of the object to be protected when the surface protection sheet is peeled and removed from the object to be protected with a thin thickness. .

For example, a glass panel used as the above-mentioned optical member can be thinned by performing a glass slimming process using a chemical solution such as hydrofluoric acid. In the above glass thinning process, a surface protection sheet can be used to protect the non-treated surface of the glass. When the surface protection sheet used in this application is peeled and removed from the glass panel after the treatment, the thinned glass may be cracked due to the increase in the peeling force during the process or the peeling state, etc., so the yield rate decreases. And other issues. In particular, window glass or cover glass used in foldable displays or rollable displays is thinned to a thickness of about 100 μm or less to impart flexibility. Therefore, there is a greater risk of damage when the surface protection sheet is peeled off. If the peeling strength of the surface protection sheet is set low, the load applied to the adherend can be reduced during peeling, reducing the risk of damage or deformation, but there is a risk that the protection purpose cannot be achieved, such as for the protection object The adhesion (adhesion) of the object is reduced, so that the liquid medicine will penetrate into the protected area, or in severe cases, bulge or peeling will occur from the adherend during the protection period. For brittle materials with thinner thickness such as thin glass, it is more difficult to balance the adhesiveness required for protection and the easy peelability that will not damage the adherend.

Also, as an aspect of surface protection using the above-mentioned surface protection sheet, the following aspect can be mentioned, that is, one surface protection sheet is attached to one side of one or a plurality of processing objects (such as glass plates). In this state, for example, a plurality of objects to be treated (objects to be protected) are continuously or individually conveyed into water such as a chemical solution tank or a washing tank by using a conveying mechanism such as a roller to implement the target treatment. During the transfer or in the post-transport process (placement or installation on a device, etc.), the object to be processed may be unavoidably or unintentionally subjected to external forces such as shock, vibration, deformation, etc., and this external force may become a peeling load and cause There is a concern that the surface protection sheet is detached from the object to be treated. In addition, in an aspect where physical processing such as dicing or grinding is performed on the object to be processed such as a semiconductor wafer, external force during the physical processing may become a peeling load, which may cause edge peeling of the surface protection sheet. When such end peeling occurs, there is a possibility that the purpose of protection cannot be achieved, for example, liquid medicine, etc. may infiltrate into the protected area.

The present invention was made in view of the above circumstances, and an object of the present invention is to provide a surface protection sheet that can be used even in a manufacturing process including a step of treating the protected object in a liquid, for example, in a state of being attached to the protected object. When it is used in the case, it is not easy to peel off from the end due to external forces such as vibration or physical treatment during the process, and it can be peeled without damaging or deforming the object to be protected during peeling. Another related object is to provide a treatment method using the above-mentioned surface protection sheet. [Technical means to solve the problem]

The bending stiffness value at 25°C of the surface protection sheet according to one aspect provided in this specification is in the range of 1.0×10 ^-6 to 1.0×10 ^-2 Pa·m ³ . In addition, the water peeling force FW0 of the above-mentioned surface protection sheet is 1.0 N/20 mm or less, and the above-mentioned water peeling force FW0 refers to the surface-attached surface protection sheet of alkali glass having a water contact angle of 20 degrees or less. After keeping the bonding surface at 23°C and 50% RH for 1 hour, supply 20 μL of distilled water between the alkali glass and the bonding surface, and let the distilled water enter one end of the interface between the alkali glass and the bonding surface After that, it was measured under the conditions of temperature 23°C, peeling angle 180° and speed 300 mm/min.

The inventors of the present invention are advancing research and development of an adhesive sheet (water-releasable adhesive sheet) that can be easily peeled off with an aqueous liquid such as water and that has improved water resistance reliability at the time of joining. According to this water-releasable adhesive sheet, the adhesive sheet can be removed from the adherend without causing damage to the adherend that is the object to be peeled or with little physical load by water peeling using an aqueous liquid such as water. In the technology disclosed herein, the above-mentioned water stripping is utilized. Specifically, since the above-mentioned surface protection sheet has a water peeling force FW0 of 1.0 N/20 mm or less, peeling (water peeling) can be achieved without damaging or deforming the adherend (protected object) during peeling. In addition, since the bending stiffness of the above-mentioned surface protection sheet at 25°C is in the range of 1.0×10 ^-6 to 1.0×10 ^-2 Pa·m ³ , it is convenient to attach the above-mentioned surface protection sheet to the protective State of the object When an external force such as vibration is applied to the object to be protected during the process of treating the object in a liquid such as a chemical or water, the above-mentioned surface protection sheet is not likely to be peeled off from the edge in response to the external force.

Also, the water peeling force FW0 of the surface protection sheet of another aspect provided by this specification is less than 1.0 N/20 mm, and the above water peeling force FW0 is that of alkali glass having a surface with a water contact angle of 20 degrees or less. After keeping the bonding surface of the surface-attached surface protection sheet at 23°C and 50% RH for 1 hour, supply 20 μL of distilled water between the alkali glass and the bonding surface, and let the distilled water enter the alkali After one end of the interface between the glass and the bonding surface, it is measured at a temperature of 23°C, a peeling angle of 180°, and a speed of 300 mm/min. In addition, the starting point peeling force of the above-mentioned surface protection sheet is 0.5 N/10 mm or more, and the above-mentioned starting point peeling force is the adhesive surface of the surface-attached surface protection sheet of alkali glass having a surface with a water contact angle of 20 degrees or less. After 24 hours at 23°C and 50% RH, add 20 μL of distilled water dropwise between the alkali glass and the bonding surface, at a temperature of 23°C, a peeling angle of 20° and a speed of 1000 mm/min determined below. Since the above-mentioned surface protection sheet has a water peeling force FW0 of 1.0 N/20 mm or less, peeling in the presence of water enables peeling and removal without damaging or deforming the adherend (object to be protected). In addition, since the above-mentioned surface protection sheet has the above-mentioned starting point peeling force of 0.5 N/10 mm or more, even if the vibration in the conveying step or the physical load in the physical treatment step is applied to the thickness direction of the surface protection sheet When an external force (also referred to as a physical load or a peeling load) may cause peeling of the edge of the surface protection sheet, peeling from the edge does not easily occur.

In some preferred aspects, the above-mentioned water peeling force FW0 [N/20 mm] of the surface protection sheet is 50% or less of the adhesive force F0 [N/20 mm]. Here, the above-mentioned adhesive force F0 refers to the adhesive surface of the alkali glass having a surface with a water contact angle of 20 degrees or less, and the surface-attached surface protection sheet is kept at 23°C and 50%RH for 1 hour. Peel strength [N/20 mm] measured under the conditions of temperature 23°C, peel angle 180° and speed 300 mm/min. The surface protection sheet that satisfies the above characteristics can be easily peeled from the object to be protected by performing peeling in the presence of water during peeling, and on the other hand, maintains good adhesion to the object to be protected during protection. state.

In some aspects, the surface protection sheet includes an adhesive layer and a substrate layer supporting the adhesive layer. By having such a structure, a surface protection sheet can have the protective function by the base material layer located in the back side, and the adhesiveness to the object to be protected by the adhesive agent layer.

In some preferred aspects, the above-mentioned adhesive layer contains a water affinity agent. According to the adhesive layer containing a water affinity agent, it is easy to obtain an adhesive that satisfies both the adhesive force and the water releasability in the normal state (normal state) preferably.

In some preferred aspects, the thickness (total thickness) of the surface protection sheet is 20-200 μm. By having a total thickness equal to or greater than a specific value, there is a tendency that the edge peeling resistance during the process is also improved. Moreover, the surface protection sheet which has the said total thickness is easy to exhibit a favorable protective function. For example, it tends to be easy to obtain protective properties such as preventing the infiltration of a chemical solution.

The surface protection sheet disclosed herein is suitable, for example, as a surface protection sheet used in the step of chemically and/or physically treating a glass or a semiconductor wafer in a liquid. In the process including the above-mentioned processing steps, the surface protection sheet attached to the glass or semiconductor wafer as the object to be protected is less likely to be peeled off from the end. In addition, when peeling after the above-mentioned manufacturing process, it is possible to achieve smooth peeling from the glass or semiconductor wafer which is the object to be protected by water peeling. The surface protection sheet having the above-mentioned water releasability can achieve peeling without damaging the object to be protected based on its water releasability even when the object to be protected is a thin and brittle material such as thin glass. For example, in the aspect where the above-mentioned processing step is a step of thinning the glass or semiconductor wafer, the thickness of the object to be protected during peeling is smaller than that at the time of sticking, and the risk of damage is greater. By utilizing the surface protection sheet disclosed herein for such applications, peeling of the edges is less likely to occur, and easy peelability (easy water peelability) that does not damage the object to be protected can be realized.

Moreover, according to this specification, the method of processing an adherend is provided. The treatment method includes: a step of attaching a surface protection sheet to the surface of an adherend having a water contact angle of 20 degrees or less; protecting the adherend with the surface protection sheet attached along the surface a step of applying a physical load in the thickness direction of the sheet; and a step of peeling the above-mentioned surface protection sheet in the presence of water to remove it from the above-mentioned adherend. In addition, the water peeling force FW0 of the above-mentioned surface protection sheet is 1.0 N/20 mm or less, and the starting point peeling force is 0.5 N/10 mm or more. [Water Peeling Force FW0] The above-mentioned water peeling force FW0 refers to the bonded surface of the alkali glass with a surface with a water contact angle of 20 degrees or less, which is attached to the surface protection sheet. 20 μL of distilled water is supplied between the alkali glass and the bonding surface, and after the distilled water enters one end of the interface between the alkali glass and the bonding surface, the temperature is 23°C, the peeling angle is 180 degrees, and the speed is 300 mm/min. The measured water peeling force [N/20 mm]. [Peel force at starting point] The above starting point peeling force is measured on the surface of alkali glass with a water contact angle of 20 degrees or less on the bonding surface of the surface protection sheet, after being kept at 23°C and 50%RH for 24 hours Drop 20 μL of distilled water between the glass and the bonding surface, and measure the maximum stress [N/10 mm] at the initial stage of peeling under the conditions of a temperature of 23°C, a peeling angle of 20 degrees, and a speed of 1000 mm/min. In the method of treating the adherend including the step of applying a physical load to the adherend to which the surface protection sheet is attached in the thickness direction of the surface protection sheet, the peeling force is 0.5 N/10 mm or more by using the above starting point For the surface protection sheet, the above surface protection sheet is less likely to be peeled off from the end in response to the physical load applied to the end of the surface protection sheet. In addition, since the water peeling force FW0 of the above-mentioned surface protection sheet is 1.0 N/20 mm or less, the adherend (object to be protected) can be prevented from being damaged by peeling the surface protection sheet from the adherend in the presence of water. or deformation to remove the surface protection sheet.

In some preferable aspects, the said water peeling force FW0 [N/20 mm] of the said surface protection sheet is 50% or less of the adhesive force F0 [N/20 mm]. Here, the above-mentioned adhesive force F0 refers to the adhesive surface of the alkali glass having a surface with a water contact angle of 20 degrees or less, and the surface-attached surface protection sheet is kept at 23°C and 50%RH for 1 hour. Peel strength [N/20 mm] measured under the conditions of temperature 23°C, peel angle 180° and speed 300 mm/min. By using a surface protection sheet that satisfies the above characteristics, the adherend can be supplied to the target treatment in a state of good adhesion with the surface protection sheet, and on the other hand, the surface protection sheet can be removed in the step of removing the surface protection sheet. The sheet is easily removed from the adherend.

As the above-mentioned surface protection sheet, a surface protection sheet including an adhesive layer and a substrate layer supporting the adhesive layer can be preferably used.

As an example of the process of applying a physical load to the said adherend to which the said surface protection sheet was stuck along the thickness direction of this surface protection sheet, a conveyance process and a physical processing process are mentioned. The surface protection sheet disclosed herein is less likely to produce an edge in response to a physical load applied along the thickness direction of the surface protection sheet in a processing method that includes a transport process that is prone to vibration, or a physical treatment such as cutting the adherend. Peel, so that the target protection can be achieved.

As described above, according to this specification, there is provided a surface protection sheet used in any of the methods of treating an adherend disclosed herein. In one aspect, the water peeling force FW0 of the surface protection sheet is 1.0 N/20 mm or less, and the starting point peeling force is 0.5 N/10 mm or more, so by applying the treatment method disclosed herein, both With respect to the physical load applied along the thickness direction of the surface protection sheet, adherence and maintenance of end peeling and smooth peeling and removal are not easily generated. The surface protection sheet is particularly suitable for the method of treating the adherend disclosed herein.

Hereinafter, preferred embodiments of the present invention will be described. Furthermore, the matters necessary for implementing the present invention other than those specifically mentioned in this specification can be understood by the trader based on the hints about the implementation of the invention described in this specification and the technical knowledge at the time of filing the application. The present invention can be implemented based on the contents disclosed in this specification and common technical knowledge in this field. In addition, in the following drawings, members and locations that perform the same functions are sometimes described with the same symbols attached thereto, and overlapping descriptions are sometimes omitted or simplified. In addition, the embodiments described in the drawings are schematic for clearly describing the present invention, and do not necessarily represent the dimensions or scales of the products actually provided exactly.

<Constitution example of surface protection sheet> The cross-sectional structure of the surface protection sheet of an embodiment is shown in FIG. 1. As shown in Figure 1, the surface protection sheet 1 is in the form of an adhesive sheet with one-sided adhesiveness, that is, it has an adhesive surface 1A, and an adhesive layer is provided on one side 10A of a sheet-shaped base material layer (support base material) 10. Agent layer 20. The surface protection sheet 1 is used by affixing the surface 20A of the adhesive layer 20 as the adhesive surface 1A to an adherend (object to be protected). The back surface 10B of the base material layer 10 (the surface opposite to the surface 10A) is also the back surface 1B of the surface protection sheet 1 and constitutes the outer surface of the surface protection sheet 1 . The surface protection sheet 1 before use (that is, before it is attached to the adherend) can be in the form of a surface protection sheet 50 with a release liner, that is, the adhesive surface 1A becomes the release surface from at least the adhesive layer 20 side. Release liner 30 for protection. Alternatively, the surface protection sheet may be a form in which the other side (back side) 10B of the base material layer 10 is a peeling surface, and the adhesive layer 20 is in contact with the surface protection sheet 1 by being wound up in a roll shape. on the back side, so that its surface (connecting surface 1A) is protected.

Moreover, as shown in FIG. 2, in the surface protection sheet 2, the base material layer 10 may have a multilayer structure. In this embodiment, the surface protection sheet 2 has a structure in which an adhesive layer 20 is provided on one side 10A of a sheet-shaped base material layer (support base material) 10, and the base material layer 10 has a structure consisting of a first layer 11 and a second layer 12. Laminated structure. Specifically, the base material layer 10 includes the first layer 11 which is the main layer of the base material layer 10 , and the second layer 12 which constitutes a surface (back surface) 10B of the base material layer 10 . In this embodiment, the second layer 12 is a layer containing inorganic materials. The adhesive layer 20 is in close contact with the surface 10A of the first layer 11 side of the base layer 10 . The surface protection sheet 2 before use (that is, before being attached to the adherend) can be in the form of a surface protection sheet 50 with a release liner attached, that is, the adhesive surface 2A becomes the release surface from at least the adhesive layer 20 side The release liner 30 protection. Alternatively, it may be a surface protection sheet in which the other side (back side) 10B of the base material layer 10 is a peeling surface, and the adhesive layer 20 is in contact with the surface protection sheet 2 by being wound up in a roll. on the back, so that its surface is protected.

<Characteristics of Surface Protection Sheet> (Bending Stiffness at 25°C) In some aspects, the surface protection sheet preferably has a bending stiffness at 25°C (bending stiffness at 25°C) of 1.0×10 ^-6 to 1.0 Within the range of ×10 ^-2 Pa·m ³ . The surface protection sheet that satisfies this characteristic even if external force such as vibration is applied during the process of treating the object to be protected in a liquid such as chemical solution or water in the state where the surface protection sheet is attached to the object to be protected When it is used, it is not easy to peel off from the end due to the external force. Specifically, by making the surface protection sheet have a specific range of rigidity (bending stiffness at 25°C), the stress (peeling stress) against external forces such as vibrations that may cause the edge of the surface protection sheet to peel during the above-mentioned process is increased. , Even when external force such as vibration is applied during the above process, it can prevent the end peeling or reduce the risk of end peeling. Furthermore, when the bending stiffness at 25°C is below a specific value (for example, 10 ^-2 Pa·m ³ ), the surface protection sheet has a rigidity suitable for surface protection, and it is easy to obtain good peeling workability and handleability. There is a tendency to improve the surface followability of the protected object.

From the viewpoint of end peeling resistance, the bending stiffness value D at 25°C may be at least 5.0×10 ^-6 Pa·m ³ , preferably at least 1.0×10 ^-5 Pa·m ³ , more preferably at least 5.0×10 -6 Pa·m 3 10 ^-5 Pa·m ³ or more, more preferably 1.0×10 ^-4 Pa·m ³ or more, and may be 3.0×10 ^-4 Pa·m ³ or more. From the viewpoints of edge peeling resistance, peeling workability, handling, etc., the above-mentioned bending stiffness value D at 25°C is preferably 5.0×10 ^-3 Pa·m ³ or less, more preferably 1.0×10 ^-3 Pa·m ³ or less, more preferably 5.0×10 ^-4 Pa·m ³ or less, and may be 1.0×10 ^-5 Pa·m ³ or less. It is advantageous that the above-mentioned 25° C. bending stiffness value D is lower within a specific range in terms of improving the surface followability of the object to be protected. In some other aspects, the value of the bending stiffness at 25°C is not particularly limited, and may be less than 1.0×10 ^-6 Pa·m ³ or may exceed 1.0×10 ^-2 Pa·m ³ .

The above 25°C bending stiffness value D[Pa·m ³ ] is based on the assumption that the thickness of the substrate layer is h[m] and the Poisson’s ratio of the substrate is ν, and the surface protection sheet is placed at a temperature of 25°C When the tensile elastic modulus (25°C tensile elastic modulus) is E[Pa], the value obtained by the formula: D=Eh ³ /12(1-ν ² ). Furthermore, the bending stiffness of the adhesive layer is very small compared to the bending stiffness of the base layer, so the bending stiffness of the surface protection sheet can depend on the bending stiffness of the base layer. Therefore, in this specification, the bending stiffness value D of the surface protection sheet refers to a value converted into a unit cross-sectional area of the substrate layer constituting the surface protection sheet. The cross-sectional area of the base layer is calculated based on the thickness of the base layer. The thickness h of the substrate layer is set to a value obtained by subtracting the thickness of the adhesive layer from the measured value of the thickness of the surface protection sheet. Poisson's ratio ν is a value (dimensionless number) determined by the material of the substrate layer, and when the material is a resin, usually 0.35 can be used as the value of ν. The above 25°C bending stiffness value D [Pa·m ³ ] can be obtained by combining the 25°C tensile elastic modulus E [Pa] obtained from the tensile test described in the examples described later and the substrate thickness h [m] Substitute into the above formula to find out. The above 25°C bending stiffness value can be the 25°C bending stiffness value in the length direction (MD: Machine Direction), or the 25°C bending stiffness value in the width direction (TD: Transverse Direction, the direction orthogonal to MD). Therefore, It can be the 25°C bending stiffness of at least one of the 25°C bending stiffness in MD and the 25°C bending stiffness in TD, or it can be the 25°C bending stiffness in either direction of MD or TD. The 25°C bending stiffness of the surface protection sheet can be obtained mainly by selecting the material and setting the thickness of the substrate layer constituting the surface protection sheet.

(tensile elastic modulus at 25°C) Although not particularly limited, in some aspects, the 25° C. tensile modulus of the surface protection sheet may be 100 MPa or more, or may be 500 MPa or more. In some preferred aspects, the tensile modulus of elasticity at 25°C is 1000 MPa or more, more preferably 3000 MPa or more, further preferably 5000 MPa or more, and may be 6000 MPa or more. The higher the tensile elastic modulus at 25°C, the higher the bending stiffness at 25°C can be obtained. The upper limit of the tensile modulus of elasticity at 25°C is not particularly limited. For example, it may be less than 30 GPa, or less than 15 GPa, or less than 10 GPa, or less than 8000 MPa, or less than 6000 MPa. It can also be below 4500 MPa. The smaller the tensile elastic modulus at 25°C, the lower the bending stiffness at 25°C can be obtained. Moreover, the surface protection sheet which has the 25 degreeC tensile elastic modulus in the said range also tends to be favorable in peeling workability, handleability, and surface followability.

(Stress at 100% elongation at 25°C) Although not particularly limited, in some aspects, the stress at 100% elongation at 25°C of the surface protection sheet may be 10 N/mm2 or ^more , preferably 30 N/mm ² or more, preferably 50 N/mm ² or more, more preferably 80 N/mm ² or more, and may be 120 N/mm ² or more. There is a tendency that the greater the stress at the 100% elongation, the easier it is for the surface protection sheet to have a rigidity higher than a certain level, and the easier it is for edge peeling resistance to be obtained. The upper limit of the above-mentioned stress at 100% elongation is, for example, 300 N/mm ² or less, may be 200 N/mm ² or less, or may be 100 N/mm ² or less. A surface protection sheet having a stress at 100% elongation within the above range tends to exhibit good peeling workability, handleability, and surface followability.

(Break stress at 25°C) Although not particularly limited, in some aspects, the break stress at 25°C of the surface protection sheet may be 10 N/mm ² or more, suitably 30 N/mm ² or more (for example, 50 N/mm 2 /mm ² or more), preferably 100 N/mm ² or more, more preferably 120 N/mm ² or more, or 150 N/mm ² or more. There is a tendency that the surface protection sheet is more likely to have a rigidity higher than a certain level as the above-mentioned fracture stress is larger, and it is easier to obtain edge peeling resistance. The upper limit of the breaking stress is, for example, 500 N/mm ² or less, may be 300 N/mm ² or less, may be 200 N/mm ² or less, or may be 150 N/mm ² or less. A surface protection sheet having a breaking stress within the above range tends to exhibit good peeling workability, handleability, and surface followability.

(25℃break strain) Although not particularly limited, in some aspects, the breaking strain at 25°C of the surface protection sheet may be 500% or less, suitably less than 300%, preferably 250% or less, and may be 200% or less. There is a tendency that the smaller the above-mentioned breaking strain is, the easier it is for the surface protection sheet to have a rigidity equal to or higher than a certain level, and the easier it is for edge peeling resistance to be obtained. The lower limit of the above-mentioned breaking strain is, for example, 120% or more, may be 150% or more, or may be 200% or more. A surface protection sheet having a breaking strain within the above range tends to exhibit good peeling workability, handleability, and surface followability.

The above-mentioned 25° C. tensile modulus was obtained by linear regression of a stress-strain curve obtained from a tensile test described in Examples described later. In addition, the stress at 100% elongation [N/mm ² ], breaking stress [N/mm ² ], and breaking strain [%] can also be measured by a tensile test described in Examples described later. Furthermore, the mechanical property values of the adhesive layer (tensile elastic modulus, stress at 100% elongation, breaking stress, and breaking strain) are very small compared with the above-mentioned mechanical property values of the substrate layer, and the above-mentioned mechanical properties of the surface protection sheet The properties may depend on the mechanical properties of the substrate layer. Therefore, in this specification, the tensile elastic modulus, 100% elongation stress, and fracture stress of the surface protection sheet refer to the values obtained after conversion into the cross-sectional area per unit of the substrate layer constituting the surface protection sheet. The cross-sectional area of the substrate layer can be calculated based on the thickness of the substrate layer. The thickness of the base material layer is set to a value obtained by subtracting the thickness of the adhesive layer from the measured value of the thickness of the surface protection sheet. The above 25°C tensile modulus can be the 25°C tensile modulus of MD, or the 25°C tensile modulus of TD. Therefore, it can be the 25°C tensile modulus of MD and the 25°C of TD. The 25°C tensile modulus of at least one of the °C tensile modulus of elasticity, or the 25°C tensile modulus of any one of MD or TD. Similarly, the above-mentioned stress at 100% elongation, stress at break and strain at break can also be measured values of MD (stress at 100% elongation, stress at break or strain at break), and can also be measured values of TD. Therefore, it can be MD The measured value of at least one of the measured value of TD and the measured value of TD, or the measured value of either direction of MD or TD.

The above mechanical properties of the surface protection sheet (tensile elastic modulus at 25°C, stress at 100% elongation at 25°C, breaking stress at 25°C, and breaking strain at 25°C) can be mainly determined by the material of the substrate layer of the surface protection sheet. Select to set and adjust.

(Normal water peeling force FW0) One of the characteristics of the surface protection sheet disclosed herein is that the normal water peeling force FW0 is 1.0 N/20 mm or less. Such a surface protection sheet having a water peeling force FW0 of 1.0 N/20 mm or less can adhere well to an adherend, and can be easily peeled from the object to be protected by performing water peeling using an aqueous liquid such as water during peeling. More specifically, for example, a small amount of aqueous liquid is supplied between the object to be protected and the adhesive layer, and the aqueous liquid enters the interface between the object to be protected and the adhesive layer to form a starting point for peeling, thereby greatly improving Decrease the peeling strength of peeling the adhesive layer from the object to be protected. Utilizing this property, the surface protection sheet can be easily peeled off from the object to be protected by performing water peeling with an aqueous liquid such as water, without causing damage or deformation of the object to be protected. According to the surface protection sheet having this characteristic (water release characteristic), even when the object to be protected is a brittle material with a thin thickness such as thin glass, it can be peeled without damaging the adherend during peeling.

In some preferred aspects, the normal water peeling force FW0 is, for example, less than 1.0 N/20 mm, or less than 0.9 N/20 mm, or less than 0.8 N/20 mm, or 0.7 N/20 mm or less, or less than 0.6 N/20 mm, or less than 0.5 N/20 mm, or less than 0.3 N/20 mm (for example, less than 0.1 N/20 mm). The lower limit of the above-mentioned normal water peeling force FW0 can be appropriately set to achieve the desired water peeling property, and is not limited to a specific range. The lower limit of the normal water peeling force FW0 may be 0.0 N/20 mm, or 0.01 N/20 mm or more (for example, 0.1 N/20 mm or more).

The normal water peeling force FW0 refers to the bonded surface of the alkali glass with a water contact angle of 20 degrees or less. The surface is attached to the surface protection sheet. 20 μL of distilled water is supplied between the alkali glass and the bonding surface, and after the distilled water enters one end of the interface between the alkali glass and the bonding surface, the temperature is 23°C, the peeling angle is 180 degrees, and the speed is 300 mm/min. The measured water peeling force [N/20 mm]. More specifically, the normal water peeling force FW0 can be measured by the method described in the Example mentioned later.

(Normal water peel force reduction rate FW0/F0) Also, in some aspects, the surface protection sheet is preferably such that the normal water peeling force FW0 [N/20 mm] is 50% or less of the normal adhesive force F0 [N/20 mm]. In other words, the above-mentioned surface protection sheet preferably has a normal water peeling force reduction rate [%] represented by the formula: FW0/F0×100 of 50% or less. A surface protection sheet satisfying these characteristics can be adhered well to an adherend, and when peeling, the surface protection sheet can be easily peeled off from the object to be protected by performing water peeling using an aqueous liquid such as water. According to such a surface protection sheet, adhesiveness required for protection can be exhibited, and peeling without damaging the adherend can be realized at the time of peeling. In some preferred aspects, the reduction rate of the above-mentioned normal water peeling force is 30% or less, more preferably 20% or less, further preferably 10% or less, and may also be 5% or less (for example, 3% or less). According to the surface protection sheet which exhibits such a reduction rate of normal water peeling force, it can become the one which balances the bonding reliability at the time of protection and the ease of peeling at the time of peeling more favorably. The lower limit of the above-mentioned normal water peeling force reduction rate is 0% in theory, and it may be about 1% or more (for example, 2% or more) in practice.

(Normal adhesion F0) In the technology disclosed herein, the normal adhesive force F0 of the surface protection sheet is preferably designed to be higher than the above normal water peeling force FW0. The above-mentioned normal-state adhesive force F0 may be, for example, greater than 0.5 N/20 mm, typically greater than 1.0 N/20 mm. A surface protection sheet having a normal adhesive force F0 of a specific value or more tends to exhibit good adhesiveness to the object to be protected. In some preferred aspects, the normal adhesive force F0 is more than 2.0 N/20 mm, more preferably more than 3.0 N/20 mm (for example, more than 3.0 N/20 mm), and more preferably more than 5.0 N/20 mm ( For example, more than 5.0 N/20 mm), 7.0 N/20 mm or more, 8.0 N/20 mm or more, 9.0 N/20 mm or more, or 10.0/20 mm or more. The larger the normal bonding force F0 is, the easier it is to obtain a higher protection function. According to the technology disclosed in this article, even if the surface protection sheet is attached to the object to be protected with a high adhesive force, it can be peeled off with water when peeling off, so that the object to be protected will not be damaged or deformed, and the surface can be smoothly attached. The protective sheet is peeled off for removal. Therefore, the adhesive force (normal adhesive force F0) can be set higher than the conventional surface protection sheet which obtained peelability by restricting the adhesive force. This fact means that even when used in a harsher environment, sufficient protection can be ensured based on high bonding reliability, which is practically beneficial. The upper limit of the normal adhesive force F0 can be appropriately set according to the required adhesiveness, so it is not limited to a specific range. For example, it can be about 20 N/20 mm or less, or about 15 N/20 mm or less. It may be about 10 N/20 mm or less, and may be about 6 N/20 mm or less.

The normal state adhesive force F0 refers to the adhesive surface of alkali glass with a water contact angle of 20 degrees or less. The surface is attached to the surface protection sheet. Peel strength [N/20 mm] measured under the conditions of ℃, peeling angle of 180 degrees and speed of 300 mm/min. More specifically, the normal state adhesive force F0 can be measured by the method described in the Example mentioned later.

(Adhesion force F1 after immersion in warm water for 30 minutes) The surface protection sheet disclosed herein preferably has an adhesive force F1 of 0.5 N/20 mm or more after immersion in warm water for 30 minutes. A surface protection sheet that satisfies the above characteristics can maintain the adhesiveness required for protection even when it is used in a state of being attached to an object to be protected and treating the object to be protected in a liquid. For example, even if it is used in a chemical solution (typically, in the form of an aqueous solution) or warm water, there is no decrease in adhesive force due to water peelability, or the decrease in adhesive force is also suppressed, thereby maintaining the adhesive state to the adherend . Such a surface protection sheet can be, for example, excellent in protective properties that do not cause peeling from the edges during the above-mentioned submerged liquid treatment. In certain aspects, the adhesive force F1 after 30 minutes of warm water immersion is preferably 1.0 N/20 mm or more, more preferably 1.5 N/20 mm or more, further preferably 2.0 N/20 mm or more, and may also be 2.5 N/20 mm or more, or 3.0 N/20 mm or more (for example, 3.5 N/20 mm or more). It tends to be as follows: the greater the adhesion force F1 after immersion in warm water for 30 minutes, the easier it is to maintain a higher protective function even if it is used in a state where it is treated with liquid medicine or warm water. The upper limit of the adhesive force F1 after immersion in warm water for 30 minutes can be appropriately set according to the required adhesiveness, so it is not limited to a specific range, for example, it can be about 15 N/20 mm or less, or about 10 N/20 mm or less, or about 5 N/20 mm or less.

Adhesive force F1 after immersion in warm water for 30 minutes is to immerse in warm water at 60°C ± 2°C for 30 minutes on the surface of alkali glass with a water contact angle of 20 degrees or less, which is attached to the surface protection sheet. Then lift it up from the warm water and wipe off the attached water, then measure the peel strength [N/20 mm] under the conditions of temperature 23°C, peel angle 180° and speed 300 mm/min. More specifically, the adhesive force F1 after immersion in warm water for 30 minutes can be measured by the method described in Examples described later.

(Water peeling force reduction rate FW1/F1 after immersion in warm water for 30 minutes) In some aspects, the surface protection sheet is preferably such that the water peeling force FW1 [N/20 mm] after 30 minutes of warm water immersion is less than 50% of the above-mentioned adhesion force F1 [N/20 mm] after 30 minutes of warm water immersion . In other words, the above-mentioned surface protection sheet is preferably such that the water peeling force reduction rate [%] represented by the formula: FW1/F1×100 after 30 minutes of warm water immersion is 50% or less. In this way, the water peeling force FW1 after 30 minutes of warm water immersion is reduced to less than 50% of the adhesion force F1 after 30 minutes of warm water immersion. The surface protection sheet is attached to the object to be protected, for example, even in a chemical solution (typically In other words, after being used in aqueous solution) or in warm water, it also has a specific value or more of adhesive force after immersion in warm water for 30 minutes as mentioned above, and it can be peeled off without damaging or deforming the object to be protected (water peeling ). According to the surface protection sheet that satisfies the above characteristics, it can have the adhesiveness required for protection, and even when the object to be protected is a brittle material with a thin thickness such as thin glass, it can be better realized when peeling off. Peeling that causes damage to the adherend. In some aspects, the water peeling force reduction rate after immersion in warm water for 30 minutes is preferably 30% or less, more preferably 20% or less, further preferably 10% or less, especially preferably 5% or less (for example, 30% or less). %the following). According to the surface protection sheet which shows the reduction rate of the water peeling force after immersion in such warm water for 30 minutes, it can become the one which balances the bonding reliability at the time of protection and the ease of peeling at the time of peeling more favorably. The lower limit of the reduction rate of water peeling force after immersion in warm water for 30 minutes is theoretically 0%, but practically it can be about 1% or more (for example, 2% or more).

(Water peeling force FW1 after immersion in warm water for 30 minutes) In the technology disclosed herein, the water peeling force FW1 of the surface protection sheet after 30 minutes of warm water immersion is preferably designed to be lower than the above-mentioned peeling force F1 after 30 minutes of warm water immersion. The water peeling force FW1 after immersion in warm water for 30 minutes is, for example, 1.0 N/20 mm or less, or may be less than 1.0 N/20 mm, suitably 0.9 N/20 mm or less, or 0.8 N/20 mm or less. 0.6 N/20 mm or less. In some preferred aspects, the water peeling force FW1 after immersion in warm water for 30 minutes is less than 0.5 N/20 mm, more preferably less than 0.4 N/20 mm, and more preferably less than about 0.3 N/20 mm , or less than 0.2 N/20 mm, or less than 0.15 N/20 mm, or less than 0.10 N/20 mm. The surface protection sheet exhibiting the above-mentioned water peeling force FW1 after immersion in warm water for 30 minutes can exhibit good water peeling property even after being treated with liquid medicine or warm water. The lower limit of the water peeling force FW1 after immersion in warm water for 30 minutes can be appropriately set so as to exhibit desired water peeling properties, and is not limited to a specific range. The lower limit of the water peeling force FW1 after immersion in warm water for 30 minutes may be 0.0 N/20 mm, or 0.01 N/20 mm or more (for example, 0.05 N/20 mm or more).

After 30 minutes of warm water immersion, the water peeling force FW1 is based on the bonding surface of the alkali glass with a water contact angle of 20 degrees or less. , and then lifted from the warm water and wiped off the attached water, supplied 20 μL of distilled water between the soda glass and the bonding surface, and made the distilled water enter one end of the interface between the soda glass and the bonding surface, and then heated at a temperature of 23 The water peeling force [N/20 mm] measured under the conditions of ℃, peeling angle of 180 degrees and speed of 300 mm/min. More specifically, the water peeling force FW1 after immersion in warm water for 30 minutes can be measured by the method described in the Example mentioned later.

Also, in some aspects, the surface protection sheet is preferably such that the water peeling force FW1 after immersion in warm water for 30 minutes is the same as or smaller than the normal water peeling force FW0. The surface protection sheet constituted in this way will not increase the water peeling force due to aging after immersion in warm water for 30 minutes. Therefore, during the protection period, for example, in liquid treatment such as chemical solution treatment, even if it is exposed to a temperature higher than normal temperature (for example, about 40°C or higher), the adhesive force of the surface protection sheet to the adherend is also strong. No rise, or the rise of the adhesive force is suppressed, and when the surface protection sheet is peeled, based on the required water releasability, it is easy to achieve peeling without damaging the adherend. After immersion in warm water for 30 minutes, the water peeling force FW1 can be less than 70%, or less than 50%, or less than 30%, or less than 10% of the normal water peeling force FW0. The water peeling force FW1 after immersion in warm water for 30 minutes is not particularly limited, and it can be more than 0% of the normal water peeling force FW0, and can also be more than 1% (for example, more than 3%).

(Peel force at starting point in water) In addition, the surface protection sheet disclosed herein preferably has a starting point peeling force in water of 0.2 N/10 mm or more. The starting point peeling force in water is at room temperature (23-25° C.) in water at a peeling angle of 20 degrees, Measured under the condition of tensile speed 1000 mm/min. A surface protection sheet satisfying these characteristics tends to be excellent in edge peeling resistance. The external force such as vibration that may cause the edge peeling of the surface protection sheet during the process of conveyance can be considered as a high-speed peeling load applied to the object to be protected at a relatively small angle. The starting point peeling force in water under the conditions of a peeling angle of 20 degrees and a peeling speed of 1000 mm/min shows that the stress of the surface protection sheet of 0.2 N/10 mm or more to the above peeling load is above a specific value, so even in When the above-mentioned surface protection sheet is attached to the object to be protected, when an external force such as vibration is applied during the process of treating the object to be protected in a liquid such as a chemical or water, it can also exhibit excellent performance against the external force End stripping resistance. From the viewpoint of improving the anti-end peeling property, the starting point peeling force in water is more preferably 0.3 N/10 mm or more, further preferably 0.5 N/10 mm or more, especially preferably 0.6 N/10 mm or more (for example, 0.7 N/10 mm or more). N/10 mm or more). The upper limit of the starting point peeling force in water is not particularly limited, and may be, for example, 3 N/10 mm or less, or 2 N/10 mm or less (for example, 1 N/10 mm or less). The above starting point peeling force in water can be preferably realized mainly by setting the 25° C. bending stiffness value of the surface protection sheet to a specific range. More specifically, the starting point peeling force in water can be measured by the method described in the examples described later.

(Peel force at starting point) In some preferred aspects, the starting point peeling force of the surface protection sheet is 0.5 N/10 mm or more, and the above starting point peeling force is for the surface-attached surface protection of alkali glass having a surface with a water contact angle of 20 degrees or less. After keeping the bonding surface of the sheet at 23°C and 50% RH for 24 hours, add 20 μL of distilled water dropwise between the alkali glass and the bonding surface, and then peel at a temperature of 23°C, a peeling angle of 20° and a speed of 1000 Measured under the condition of mm/min. Even if the surface protection sheet satisfying the above characteristics is subjected to external forces acting on the thickness direction of the surface protection sheet such as vibration in the conveying step or physical load in the physical processing step, which may cause peeling of the edge of the surface protection sheet (Also known as physical load, peeling load), it is not easy to peel off from the end. This edge peeling resistance can be exerted against the above-mentioned physical load regardless of the presence or absence of water. From the viewpoint of improving the anti-end peeling property, the above-mentioned starting point peeling force is more preferably 0.6 N/10 mm or more, further preferably 0.7 N/10 mm or more, especially preferably 0.8 N/10 mm or more (for example, 0.9 N/10 mm or more). /10 mm or more). The upper limit of the starting point peeling force is not particularly limited, for example, it is 3 N/10 mm or less, and may be 2 N/10 mm or less (for example, 1 N/10 mm or less). The above starting point peeling force can be realized based on the composition of the adhesive (the use of the adhesion imparting agent or the selection of the type of the adhesion imparting agent, the type or amount of the water affinity agent, etc.). Moreover, it can also adjust by setting the mechanical characteristic (for example, 25 degreeC bending rigidity value) of a surface protection sheet to a specific range. More specifically, the above-mentioned starting point peel force can be measured by the method described in the examples described later.

(Moisture permeability) In some aspects, the surface protection sheet preferably has a moisture permeability measured by the cup method of 24 g/(m ² ·day) or less. With such a limited moisture permeability structure, even if the surface protection sheet is put into a liquid in the state of being attached to the adherend, the aqueous liquid will not easily penetrate into the adherend. The adhesive interface does not show the reduction of adhesive force due to water peelability, or the reduction of adhesive force is suppressed. As a result, the adhesive force with respect to an adherend is maintained, and the surface protection sheet can maintain the adhesive state with an adherend. Such a surface protection sheet can prevent peeling from the edge during, for example, submerged processing such as chemical liquid processing. In some preferred aspects, the above-mentioned moisture permeability of the surface protection sheet is about 20 g/(m ² ·day), more preferably about 16 g/(m 2 ·day), and more preferably about 12 g/(m ² ·day). g/(m ² ·day), preferably less than about 8 g/(m ² ·day), may be less than about 5 g/(m ² ·day), for example, may be about 3 g/(m ²・day) or less. Moreover, when the surface protection sheet is exposed to heat such as warm water, if the above-mentioned moisture permeability is too low, water releasability may not be effectively expressed due to aging due to the heating. From this point of view, in some aspects, the moisture permeability of the surface protection sheet is suitably 1 g/(m ² ·day) or more, preferably about 3 g/(m ² ·day) or more, more preferably More than 5 g/(m ² ·day), for example, may exceed 6 g/(m ² ·day).

More specifically, the above-mentioned moisture permeability of the surface protection sheet may be, for example, 23 g/(m ² ·day) or less, 22 g/(m ² ·day) or less, 21 g/(m ² ·day) ) above or below, 20 g/(m ²・day) above or below, 19 g/(m ²・day) above or below, 18 g/(m ²・day) above or below, 17 g/(m ²・day) or more, 16 g/(m ²・day) or more, 15 g/(m ²・day) or more, 14 g/(m ²・day) or more, 13 g/( ^m2・day) or less, 12 g/( ^m2・day) or less, 11 g/( ^m2・day) or more, 10 g/( ^m2・day) or less, 9 g /(m ²・day) above or below, 8 g/(m ²・day) above or below, 7 g/(m ²・day) above or below, 6 g/(m ²・day) above or below, 5 g/(m ²・day) or less, 4 g/(m ²・day) or less, 3 g/(m ²・day) or less, 2 g/(m ²・day) or more or below, or above or below 1 g/(m ² ·day).

The aforementioned moisture permeability of the surface protection sheet can be obtained by selecting and using an appropriate moisture-impermeable or low-moisture-permeable material (typically, a substrate). More specifically, the water vapor transmission rate of a surface protection sheet can be measured by the method described in the Example mentioned later.

＜Adhesive layer＞ The surface protection sheet disclosed herein typically has an adhesive layer. The above-mentioned adhesive layer may be, for example, a material selected from acrylic adhesives, rubber adhesives (natural rubber, synthetic rubber, and mixtures thereof), silicone adhesives, polyester adhesives, amine adhesives, etc. Adhesive layer composed of one or more adhesives among various adhesives such as urethane-based adhesives, polyether-based adhesives, polyamide-based adhesives, and fluorine-based adhesives. Here, the acrylic adhesive refers to an adhesive mainly composed of an acrylic polymer. Rubber-based adhesives and other adhesives also have the same meaning.

In addition, in this specification, an "acrylic polymer" refers to a polymer derived from a monomer component containing more than 50% by weight of an acrylic monomer. The above-mentioned acrylic monomer refers to a monomer having at least one (meth)acryl group in one molecule. In addition, in this specification, "(meth)acryl" means the meaning including acryl and methacryl. Similarly, "(meth)acrylate" means including acrylate and methacrylate, and "(meth)acrylic" means including acrylic acid and methacrylic acid. The above-mentioned acrylic polymer may be an acrylic polymer. The above-mentioned acrylic polymer may be, for example, an acrylic polymer contained as a base polymer (main constituent polymer) in a water-dispersed or solvent-based adhesive. In this case, "monomer components constituting an acrylic polymer" in this specification may be changed to "monomer components constituting an acrylic polymer". In addition, in this specification, the content of the added component expressed as the relative amount to the "monomer component constituting the polymer" or "the monomer component constituting the acrylic polymer" can be changed to "acrylic polymer" Relative amount.

(acrylic adhesive) From the viewpoint of weather resistance and the like, in some aspects, an acrylic adhesive can be preferably used as a constituent material of the adhesive layer.

As an acrylic adhesive, for example, an alkyl (meth)acrylate containing more than 35% by weight of a linear or branched alkyl group having 1 to 20 carbon atoms at the end of the ester is preferable. Acrylic polymers composed of monomer components. Hereinafter, an alkyl (meth)acrylate having an alkyl group having a carbon number of X to Y at the end of the ester may be referred to as "C _XY alkyl (meth)acrylate". The alkyl (meth)acrylates having the aforementioned chain (includes linear and branched) alkyl groups can be used alone or in combination of two or more.

In some aspects, the ratio of the C _1-20 alkyl (meth)acrylate in the whole monomer component may be, for example, 40% by weight or more, or 45% by weight or more in terms of easily obtaining a balance of properties, It may be 50 weight% or more (for example, 55 weight% or more). For the same reason, the ratio of C _1-20 alkyl (meth)acrylate in the monomer component may be, for example, 90% by weight or less, 70% by weight or less, or 65% by weight or less (for example 55% by weight or less). In some other aspects, the ratio of the C _1-20 alkyl (meth)acrylate in the whole monomer component may be, for example, 70% by weight or more, or may be 80% by weight or more in terms of easily obtaining a balance of properties , It can also be more than 90% by weight. For the same reason, the ratio of C _1-20 alkyl (meth)acrylate in the monomer component may be, for example, 99.9% by weight or less, 99.5% by weight or less, or 99% by weight or less.

As non-limiting specific examples of C _1-20 alkyl (meth)acrylates, for example: methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, ( Isopropyl methacrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, second butyl (meth)acrylate, third butyl (meth)acrylate, (meth) Amyl acrylate, isoamyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, ( Isooctyl methacrylate, Nonyl (meth)acrylate, Isononyl (meth)acrylate, Decyl (meth)acrylate, Isodecyl (meth)acrylate, Undecyl (meth)acrylate (meth)acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, (meth)acrylate ) cetyl acrylate, heptadecyl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate, nonadecyl (meth)acrylate, ( Eicosyl methacrylate, etc.

Among them, it is preferable to use at least C _4-20 alkyl (meth)acrylate, more preferably at least C _4-18 alkyl (meth)acrylate. For example, it is preferably an acrylic adhesive containing one or both of n-butyl acrylate (BA) and 2-ethylhexyl acrylate (2EHA) as the above-mentioned monomer components, especially an acrylic adhesive containing at least BA. Adhesive. Other examples of C _4-20 alkyl (meth)acrylate that can be preferably used include: isononyl acrylate, n-butyl methacrylate (BMA), 2-ethylhexyl methacrylate ester (2EHMA), isostearyl acrylate (iSTA), etc.

In some aspects, the monomer component constituting the acrylic polymer may contain C _4-18 alkyl (meth)acrylate in a ratio of 40% by weight or more. Such a monomer component containing relatively many alkyl (meth)acrylates having an alkyl group having 4 or more carbon atoms at the ester end tends to form an acrylic polymer having a high lipophilicity. According to the acrylic polymer with high lipophilicity, it is easy to form an adhesive layer that does not easily lose its adhesive force even if it is immersed in water such as warm water. The proportion of C _4-18 alkyl (meth)acrylate in the monomer components may be, for example, 60% by weight or more, 70% by weight or more, 75% by weight or more, or 80% by weight %above. It may also be a monomer component containing a C _6-18 alkyl (meth)acrylate at a ratio equal to or greater than any of the above lower limits. Also, from the viewpoint of improving the cohesiveness of the adhesive layer and preventing cohesion failure, the ratio of the _C4-18 alkyl (meth)acrylate in the monomer components is suitably set at 99.5% by weight or less. It is 99 weight% or less, may be 98 weight% or less, and may be 97 weight% or less. From the viewpoint of improving the cohesiveness of the adhesive layer, in some aspects, the ratio of the _C4-18 alkyl (meth)acrylate to the above-mentioned monomer components is 95% by weight or less, for example, it is suitably 90% by weight or less. In some other aspects, the proportion of C _4-18 alkyl (meth)acrylate in the monomer components may be 85% by weight or less, or 75% by weight or less. It may also be a monomer component containing a C _6-18 alkyl (meth)acrylate at a ratio below any of the above upper limits.

In some aspects, it is preferable to use the proportion of C _1-4 alkyl (meth)acrylate (preferably BA) in the alkyl (meth)acrylate having the above-mentioned chain alkyl An acrylic polymer formed from a monomer component with a ratio of more than 50% by weight. According to this acrylic polymer, an adhesive having adhesive force and cohesive force suitable for surface protection can be easily obtained. C _1-4 alkyl (meth)acrylates can be used alone or in combination of two or more. The ratio of the C _1-4 alkyl (meth)acrylate in the alkyl (meth)acrylate having the above-mentioned chain alkyl group is preferably 70% by weight or more, more preferably 85% by weight or more, for example, It is more than 90% by weight. The upper limit of the ratio of C _1-4 alkyl (meth)acrylate to the alkyl (meth)acrylate having the above-mentioned chain alkyl is 100% by weight, and may be 99% by weight or less, for example, It may be less than 97% by weight.

In some aspects, the ratio of C _2-4 alkyl (meth)acrylate to the alkyl (meth)acrylate having the above-mentioned chain alkyl is more than 50% by weight (for example, more than 70% by weight , or more than 85% by weight, or more than 90% by weight). Specific examples of _C2-4 alkyl (meth)acrylates include: ethyl acrylate, propyl acrylate, isopropyl acrylate, BA, isobutyl acrylate, second butyl acrylate and third acrylate butyl ester. C _2-4 alkyl (meth)acrylates can be used alone or in combination of two or more. Using an acrylic polymer having such a monomer composition makes it easy to realize a surface protection sheet having good adhesion to an adherend. Among them, as a preferred aspect, it can be exemplified that the proportion of BA in the alkyl (meth)acrylate having the above-mentioned chain alkyl group is more than 50% by weight (for example, 70% by weight or more, or 85% by weight) above, or above 90% by weight). The ratio of C _2-4 alkyl (meth)acrylate to the alkyl (meth)acrylate having the above-mentioned chain alkyl is 100% by weight, and may be 99% by weight or less, for example, It is less than 97% by weight.

In some preferred aspects, the ratio of C _7-12 alkyl (meth)acrylate in the alkyl (meth)acrylate with the above-mentioned chain alkyl can preferably be used to exceed 50% by weight % acrylic polymer formed from monomer components. According to this acrylic polymer, it becomes easy to realize the surface protection sheet with favorable adhesiveness to an adherend. As the C _7-12 alkyl (meth)acrylate, preferably a C _8-9 alkyl (meth)acrylate, more preferably a C _8-9 alkyl acrylate, especially preferably 2EHA. C _7-12 alkyl (meth)acrylates can be used alone or in combination of two or more. The ratio of C _7-12 alkyl (meth)acrylate (preferably 2EHA) in the alkyl (meth)acrylate having the above-mentioned chain alkyl is preferably 70% by weight or more, more preferably 85% by weight % or more, for example, may be 90% by weight or more, or may be 95% by weight or more. The upper limit of the proportion of _C7-12 alkyl (meth)acrylate in the alkyl (meth)acrylate having the above-mentioned chain alkyl is 100% by weight, and may be 99% by weight or less, for example, It may be less than 97% by weight.

In some preferred aspects, the above-mentioned monomer component contains one or more kinds of alkyl methacrylates as alkyl (meth)acrylates. By using alkyl methacrylates, acrylic polymers suitable for surface protection applications can be better designed. The above-mentioned alkyl methacrylate is preferably a C _1-10 alkyl methacrylate, more preferably a C _1-4 (more preferably C _2-4 ) alkyl methacrylate. The above-mentioned alkyl methacrylate can be preferably used in combination with an alkyl acrylate. When using alkyl methacrylate and alkyl acrylate together, the weight C _AM of one or more than two kinds of alkyl methacrylate (such as C _2-4 alkyl methacrylate) and 1 The weight C _AA ratio (C _AM : C _AA ) of one or more kinds of alkyl acrylates is not particularly limited, and in some aspects, it is usually about 1:9 to 9:1, and it is suitably set at about 2 :8-8:2, preferably about 3:7-7:3, more preferably about 4:6-6:4. In several other aspects, the total amount of alkyl methacrylate (such as C ₁ alkyl methacrylate, namely methyl methacrylate (MMA)) in alkyl (meth)acrylate (C _AM +C The weight C _AM in _AA ) is usually about 30% by weight or less, suitably about 10% by weight or less, or about 5% by weight or less, more preferably about 3% by weight or less. On the other hand, the lower limit thereof may be generally about 0.1% by weight or more, about 0.5% by weight or more.

The monomer component constituting the acrylic polymer may also contain an alkyl (meth)acrylate, and other monomers (copolymerizable monomers) copolymerizable with the alkyl (meth)acrylate as needed. As the copolymerizable monomer, a monomer having a polar group (for example, a carboxyl group, a hydroxyl group, a nitrogen atom-containing ring, etc.) can be preferably used. Monomers with polar groups can help introduce cross-linking points into acrylic polymers, or improve the cohesion of adhesives. A copolymerizable monomer can be used individually by 1 type or in combination of 2 or more types.

The following are mentioned as a non-limiting specific example of a copolymerizable monomer. Carboxyl-containing monomers: such as acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, methacrylic acid, etc. Monomers containing acid anhydride groups: such as maleic anhydride and itaconic anhydride. Hydroxyl-containing monomers: such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate , 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, (meth)acrylic acid 12-hydroxylauryl ester, hydroxyalkyl (meth)acrylate such as (4-hydroxymethylcyclohexyl)methyl (meth)acrylate, and the like. Monomers containing sulfonic acid groups or phosphoric acid groups: such as styrenesulfonic acid, allylsulfonic acid, sodium vinylsulfonate, 2-(meth)acrylamide-2-methylpropanesulfonic acid, (methyl ) acrylamidopropanesulfonic acid, sulfopropyl (meth)acrylate, (meth)acryloxynaphthalenesulfonic acid, 2-hydroxyethyl acryloyl phosphate, etc. Epoxy-containing monomers: epoxy-containing acrylates such as glycidyl (meth)acrylate or 2-ethyl glycidyl (meth)acrylate, allyl glycidyl ether, (methyl) ) glycidyl acrylate, etc. Monomers containing cyano groups: such as acrylonitrile, methacrylonitrile, etc. Monomers containing isocyanate groups: such as 2-isocyanatoethyl (meth)acrylate, etc. Monomers containing amide groups: such as (meth)acrylamide; N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N,N -Dipropyl(meth)acrylamide, N,N-diisopropyl(meth)acrylamide, N,N-di(n-butyl)(meth)acrylamide, N,N- Di(tertiary butyl)(meth)acrylamide and other N,N-dialkyl(meth)acrylamide; N-ethyl(meth)acrylamide, N-isopropyl(methyl) ) acrylamide, N-butyl (meth)acrylamide, N-n-butyl (meth)acrylamide, etc. N-alkyl (meth)acrylamide; N-vinyl acetamide, etc. N-vinyl carboxylic acid amides; monomers with hydroxyl and amido groups, such as N-(2-hydroxyethyl)(meth)acrylamide, N-(2-hydroxypropyl)(methyl) ) acrylamide, N-(1-hydroxypropyl)(meth)acrylamide, N-(3-hydroxypropyl)(meth)acrylamide, N-(2-hydroxybutyl)(meth)acrylamide N-hydroxyalkyl (meth)acrylamide such as N-(3-hydroxybutyl)(meth)acrylamide, N-(4-hydroxybutyl)(meth)acrylamide Amide; monomers with alkoxy and amido groups, such as N-methoxymethyl (meth)acrylamide, N-methoxyethyl (meth)acrylamide, N-butoxy N-alkoxyalkyl(meth)acrylamide such as methyl(meth)acrylamide; and N,N-dimethylaminopropyl(meth)acrylamide, N-(formyl base) acrylyl 𠰌line, etc. Amino group-containing monomers: such as aminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, tert-butylaminoethyl (meth)acrylate. Monomers with epoxy groups: eg glycidyl (meth)acrylate, methyl glycidyl (meth)acrylate, allyl glycidyl ether. Monomers with rings containing nitrogen atoms: such as N-vinyl-2-pyrrolidone, N-methylvinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinyl Pyrimidine, N-vinylpiperone, N-vinylpyrrolidone, N-vinylpyrrole, N-vinylimidazole, N-vinylpyrazole, N-(meth)acryl-2-pyrrolidone , N-(meth)acrylpiperidine, N-(meth)acrylpyrrolidine, N-vinyl 𠰌line, N-vinyl-3-𠰌linone, N-vinyl-2- Caprolactam, N-vinyl-1,3-㗁𠯤-2-one, N-vinyl-3,5-𠰌linedione, N-vinylpyrazole, N-vinylisoxazole, N-vinylthiazole, N-vinylisothiazole, N-vinylpyrrole, etc. (for example, lactams such as N-vinyl-2-caprolactam). Monomers having a succinimide skeleton: such as N-(meth)acryloxymethylene succinimide, N-(meth)acryl-6-oxyhexamethylene succinimide Amines, N-(meth)acryl-8-oxyhexamethylenesuccinimide, and the like. Maleimides: such as N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, N-benzene Maleic imide, etc. Iconimides: such as N-methyl iconimide, N-ethyl iconimide, N-butyl iconimide, N-octyl iconimide, N- 2-Ethylhexyl iconimide, N-cyclohexyl iconimide, N-lauryl iconimide, etc. Aminoalkyl (meth)acrylates: such as aminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, N,N-dimethacrylate Ethylaminoethyl ester, tert-butylaminoethyl (meth)acrylate. Alkoxy-containing monomers: such as 2-methoxyethyl (meth)acrylate, 3-methoxypropyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, (methoxyethyl) base) propoxyethyl acrylate, butoxyethyl (meth)acrylate, ethoxypropyl (meth)acrylate and other alkoxyalkyl (meth)acrylates; methoxyethylene glycol Alkoxyalkylene glycol (meth)acrylates such as (meth)acrylate and methoxypolypropylene glycol (meth)acrylate. Alkoxysilyl-containing monomers: such as 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 3-(methyl) base) acryloxypropylmethyldimethoxysilane, 3-(meth)acryloxypropylmethyldiethoxysilane. Vinyl esters: such as vinyl acetate, vinyl propionate, etc. Vinyl ethers: vinyl alkyl ethers such as methyl vinyl ether or ethyl vinyl ether. Aromatic vinyl compounds: such as styrene, α-methylstyrene, vinyltoluene, etc. Olefins: such as ethylene, butadiene, isoprene, isobutylene, etc. (Meth)acrylates with alicyclic hydrocarbon groups: e.g. cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, iso(meth)acrylate, dicyclopentyl (meth)acrylate ester, adamantyl (meth)acrylate, etc. (Meth)acrylate having an aromatic hydrocarbon group: for example, phenyl (meth)acrylate, phenoxyethyl (meth)acrylate, benzyl (meth)acrylate, etc. In addition, (meth)acrylates containing heterocycles such as tetrahydrofurfuryl (meth)acrylate, (meth)acrylates containing halogen atoms such as (meth)acrylates containing vinyl chloride or fluorine atoms, polysilicon Silicon atom-containing (meth)acrylates such as oxygen (meth)acrylates, (meth)acrylates obtained from terpene compound derivative alcohols, etc.

When using such a copolymerizable monomer, the usage-amount is not specifically limited, It is suitably made into 0.01 weight% or more of the whole monomer component. From the viewpoint of exerting the use effect of the copolymerizable monomer more favorably, the usage-amount of the copolymerizable monomer may be 0.1% by weight or more, or 0.5% by weight or more of the whole monomer component. Moreover, from the viewpoint of easily obtaining a balance of adhesive properties, the usage-amount of the copolymerizable monomer is suitably 50 weight% or less of the whole monomer component, Preferably it is 40 weight% or less.

所表示之N-乙烯基環狀醯胺。此處，通式(1)中，R ¹為2價有機基，具體而言為-(CH ₂) _n-。n為2～7(較佳為2、3或4)之整數。其中，可較佳地採用N-乙烯基-2-吡咯啶酮。作為具有氮原子之單體之其他較佳例，可例舉(甲基)丙烯醯胺。 In some aspects, the monomer components that make up the acrylic polymer may include monomers having nitrogen atoms. By using monomers with nitrogen atoms, the cohesion of the adhesive can be improved, and the adhesive force can be better improved. The monomer having a nitrogen atom may be used alone or in combination of two or more. A preferable example of the monomer having a nitrogen atom is a monomer having a nitrogen atom-containing ring. As a monomer having a nitrogen atom-containing ring, those exemplified above can be used, for example, the general formula (1) can be used:

Represented N-vinyl cyclic amides. Here, in the general formula (1), R ¹ is a divalent organic group, specifically -(CH ₂ ) _n -. n is an integer of 2-7 (preferably 2, 3 or 4). Among them, N-vinyl-2-pyrrolidone can be preferably used. (Meth)acrylamide is mentioned as another preferable example of the monomer which has a nitrogen atom.

The amount of monomers having nitrogen atoms (preferably monomers having rings containing nitrogen atoms) is not particularly limited, for example, it can be more than 1% by weight or more than 3% by weight of the monomer components as a whole, and further It may be 5% by weight or more or 7% by weight or more. In some aspects, from the viewpoint of improving the adhesive force, the amount of the monomer having a nitrogen atom may be 10% by weight or more, 12% by weight or more, or 15% by weight of the entire monomer component. More than above, 20 weight% or more may be sufficient. Moreover, the usage-amount of the monomer which has a nitrogen atom is suitably set to 40 weight% or less of the whole monomer component, for example, may be 35 weight% or less, may be 30 weight% or less, and may be 25 weight% or less. In other several aspects, the usage-amount of the monomer which has a nitrogen atom may be 20 weight% or less of the whole monomer component, for example, and may be 16 weight% or less. In other several aspects, the usage-amount of the monomer which has a nitrogen atom may be 12 weight% or less of the whole monomer component, for example, may be 8 weight% or less, and may be 4 weight% or less.

In some aspects, the monomer component comprises a carboxyl-containing monomer. Acrylic acid (AA) and methacrylic acid (MAA) are mentioned as a preferable example of a carboxyl group containing monomer. AA and MAA can also be used together. When using AA and MAA together, these weight ratios (AA/MAA) are not specifically limited, For example, it can be made into the range of about 0.1-10. In some aspects, the above-mentioned weight ratio (AA/MAA) may be, for example, about 0.3 or more, or about 0.5 or more. Moreover, the said weight ratio (AA/MAA) may be about 4 or less, for example, and may be about 3 or less.

By using carboxyl group-containing monomers, water-based liquids such as water can be rapidly attached to the surface of the adhesive layer. This fact can contribute to the reduction of the water peeling force. The amount of the carboxyl group-containing monomer used may be, for example, 0.05% by weight or more, 0.1% by weight or more, 0.3% by weight or more, 0.5% by weight or more, or 0.8% by weight of the entire monomer component. % or more, may be 1.2% by weight or more, or may be 1.5% by weight or more. By using more than a specific amount of the carboxyl group-containing monomer, the cohesive force or crosslink density of the adhesive layer can be increased. The ratio of the above-mentioned carboxyl group-containing monomer may be, for example, 15% by weight or less, 10% by weight or less, 5% by weight or less, 4.5% by weight or less, or 3.5% by weight or less. It may be 3.0 weight% or less, and may be 2.5 weight% or less. It is preferable that the amount of the carboxyl group-containing monomer is not too much to suppress the diffusion of water to the entire adhesive layer, and to suppress the reduction of the adhesive force when it is in contact with an aqueous liquid such as warm water immersion. In addition, it is also advantageous from the viewpoint of preventing the water used for measuring the water peeling force from being absorbed by the adhesive layer and insufficient water during peeling if the amount of the carboxyl group-containing monomer used is not too large. In addition, the technology disclosed herein can also be preferably implemented in an aspect in which the above-mentioned monomer component does not substantially contain a carboxyl group-containing monomer. From this point of view, the ratio of the carboxyl group-containing monomer in the monomer component may be, for example, less than 1% by weight, less than 0.3% by weight, or less than 0.1% by weight.

In some aspects, the monomer component may comprise a hydroxyl-containing monomer. By using hydroxyl-containing monomers, the cohesion or cross-linking density of the adhesive can be adjusted to improve the adhesive force. As the hydroxyl group-containing monomer, those exemplified above can be used, for example, 2-hydroxyethyl acrylate (HEA) or 4-hydroxybutyl acrylate (4HBA) can be preferably used. The hydroxyl group-containing monomer may be used alone or in combination of two or more.

When using a hydroxyl group-containing monomer, the usage amount is not particularly limited, and may be, for example, 0.01% by weight or more, 0.1% by weight or more, or 0.5% by weight or more of the entire monomer component. In some preferred aspects, the usage amount of the hydroxyl group-containing monomer is more than 1% by weight, more preferably more than 5% by weight, more preferably more than 10% by weight, for example, it can be 12% by weight %above. Also, from the viewpoint of suppressing the water absorption of the adhesive layer, in some aspects, the usage amount of the hydroxyl group-containing monomer is suitably set to, for example, 40% by weight or less of the whole monomer component, and may be set to 30% by weight. The following may be 20% by weight or less, 15% by weight or less, 10% by weight or less, 5% by weight or less, or 3% by weight or less. The technique disclosed herein can also be implemented in an aspect in which no hydroxyl group-containing monomer is substantially used as the monomer component of the adhesive layer.

In some preferred aspects, the monomer component of the acrylic polymer is combined with a monomer having a nitrogen atom (for example, a monomer containing an amide group such as (meth)acrylamide, a ring containing a nitrogen atom such as NVP, etc. monomers), and monomers containing hydroxyl groups (such as HEA, 4HBA) as monomers with polar groups (monomers containing polar groups). Thereby, the adhesive force can be effectively improved. In the aspect of using a monomer having a nitrogen atom and a monomer containing a hydroxyl group in combination, the weight ratio ( _AN /A _OH ) of the amount _AN of the monomer having a nitrogen atom to the amount A _OH of the monomer containing a hydroxyl group is equal to It is not specifically limited, For example, it may be 0.1 or more, 0.5 or more, 0.8 or more, 1.0 or more, or 1.2 or more. Moreover, the said weight ratio ( _AN / _AOH ) may be 10 or less, 5 or less, 3 or less, or 1.5 or less, for example.

In some aspects, the monomer component may comprise an alkoxysilyl-containing monomer. The alkoxysilyl group-containing monomer is typically an ethylenically unsaturated monomer having at least 1 (preferably more than 2, such as 2 or 3) alkoxysilyl groups in one molecule, Specific examples thereof are as described above. The above-mentioned alkoxysilyl group-containing monomers may be used alone or in combination of two or more. By using an alkoxysilyl group-containing monomer, a crosslinked structure formed by a condensation reaction of silanol groups (silanol condensation) can be introduced into the adhesive layer. Furthermore, the alkoxysilyl group-containing monomer can also be understood as the following silane coupling agent.

In the aspect where the monomer component contains an alkoxysilyl group-containing monomer, the ratio of the alkoxysilyl group-containing monomer to the entire monomer component can be, for example, 0.005% by weight or more. 0.01% by weight or more. Also, from the viewpoint of improving the adhesion to the adherend, the ratio of the alkoxysilyl group-containing monomer may be, for example, 0.5% by weight or less, 0.1% by weight or less, or 0.05% by weight. the following.

Also, from the viewpoint of gelation suppression, the monomer components of the acrylic polymer of some preferred aspects are alkoxyalkyl (meth)acrylate and alkoxypolyalkylene glycol (meth) base) The total ratio of acrylates is limited to less than 20% by weight. The total ratio of the above-mentioned alkoxyalkyl (meth)acrylate and alkoxypolyalkylene glycol (meth)acrylate is more preferably less than 10% by weight, more preferably less than 3% by weight, More preferably, it is less than 1% by weight. In some aspects, the above-mentioned monomer components do not substantially contain alkoxyalkyl (meth)acrylate and alkoxypolyalkylene glycol (meth)acrylate (Content: 0 to 0.3% by weight). Likewise, the monomer component of the acrylic polymer disclosed herein may or may not contain an alkoxy group-containing monomer in a ratio of less than 20% by weight. The amount of the alkoxy-containing monomer in the above-mentioned monomer components is preferably less than 10% by weight, more preferably less than 3% by weight, more preferably less than 1% by weight, and most preferably In this sample, the above-mentioned monomer component does not substantially contain an alkoxy group-containing monomer (content 0 to 0.3% by weight).

Moreover, in some preferable aspects, the monomer component of an acryl-type polymer sets the ratio of a hydrophilic monomer to an appropriate range. Thereby, water releasability can be exhibited preferably. Here, "hydrophilic monomer" in this specification refers to monomers containing carboxyl groups, monomers containing acid anhydride groups, monomers containing hydroxyl groups, monomers having nitrogen atoms (typically, (meth)acrylic Amide-containing monomers such as amide, N-vinyl-2-pyrrolidone and other monomers having rings containing nitrogen atoms) and alkoxy-containing monomers (typically, (meth)acrylic acid Alkoxyalkyl esters and alkoxypolyalkylene glycol (meth)acrylates). In this aspect, the ratio of the above-mentioned hydrophilic monomer in the monomer component of the acrylic polymer is suitably 40% by weight or less (for example, 35% by weight or less), preferably 32% by weight or less, for example, 30% by weight or less , It can also be 28% by weight or less. It is not particularly limited, and the ratio of the above-mentioned hydrophilic monomer in the monomer component of the acrylic polymer may be 1% by weight or more, may be 10% by weight or more, or may be 20% by weight or more.

In some aspects, the monomer component constituting the acrylic polymer may include an alicyclic hydrocarbon group-containing (meth)acrylate. In this way, the cohesive force of the adhesive can be improved, and the adhesive force can be enhanced. The alicyclic hydrocarbon group-containing (meth)acrylate may be used alone or in combination of two or more. As the alicyclic hydrocarbon group-containing (meth)acrylate, those exemplified above can be used, and for example, cyclohexyl acrylate or isothiol acrylate can be preferably used. The usage-amount in the case of using an alicyclic hydrocarbon group-containing (meth)acrylate is not specifically limited, For example, it can be 1 weight% or more, 3 weight% or more, or 5 weight% or more of the whole monomer component. In some aspects, the usage-amount of the alicyclic hydrocarbon group containing (meth)acrylate may be 10 weight% or more of the whole monomer component, and may be 15 weight% or more. The upper limit of the amount of alicyclic hydrocarbon group-containing (meth)acrylate is suitably set at about 40% by weight or less, such as 30% by weight or less, or 25% by weight or less (for example, 15% by weight or less, and 10% by weight or less). weight% or less).

In some preferred aspects, the acrylic polymer contains 0.05 mol-0.45 mol of a monomer having a polar group (monomer containing a polar group) per 100 g of the acrylic polymer as a monomer component. In this way, the adhesion to polar adherends is improved, for example, the adhesion after warm water immersion can also be maintained at a high level. It is considered that the interfacial adhesive force is improved by introducing the above-mentioned polar group into the acrylic polymer, for example, based on hydrogen bonding to polar adherends such as glass. As the polar group-containing monomer, the above-mentioned carboxyl-containing monomers (typically, AA, MAA, etc.), hydroxyl-containing monomers (typically, HEA, 4HBA, etc.), and nitrogen atom-containing monomers can be used. (Typically, 1 type or 2 or more types of amide group-containing monomers such as (meth)acrylamide, and monomers having a nitrogen atom-containing ring such as NVP). Regarding the ratio of the polar group-containing monomer in the monomer component of the acrylic polymer, it is appropriate to set it at 0.10 mol per 100 g of the acrylic polymer from the viewpoint of effectively exerting the function of the polar group-containing monomer. or more, preferably 0.15 mol or more, more preferably 0.20 mol or more, for example, may be 0.24 mol or more. Also, the upper limit of the ratio of the polar group-containing monomer in the monomer component of the acrylic polymer is suitably 0.40 mol or less, preferably 0.35 mol or less, per 100 g of the acrylic polymer. 0.30 mol or less.

The composition of the monomer component may be -75°C or higher and -10°C or lower based on the glass transition temperature (hereinafter, also referred to as "polymer glass transition temperature") obtained by the Fox formula based on the composition of the monomer component mode setting. In some aspects, the glass transition temperature (Tg) of the above-mentioned polymer (such as an acrylic polymer, typically an acrylic polymer) is suitably below -15°C, preferably below -20°C, more preferably - 25°C or lower, more preferably -30°C or lower, and may be -40°C or lower (eg -55°C or lower). When Tg of the said polymer becomes low, there exists a tendency for the adhesiveness of an adhesive layer to a base material layer or the adhesiveness to an adherend to improve generally. According to the adhesive layer, infiltration of water into the interface between the adherend and the adhesive layer is easily suppressed in a state where the peeling of the adhesive layer is not intended. This is advantageous from the viewpoint of suppressing a decrease in adhesive force when the film is in contact with an aqueous liquid, such as immersion in warm water. Moreover, Tg of a polymer may be -70 degreeC or more from a viewpoint of easy improvement of adhesive force, and may be -65 degreeC or more, for example. In some other aspects, the above Tg may be -60°C or higher, -50°C or higher, -45°C or higher, or -40°C or higher, for example.

Here, as shown below, the above-mentioned Fox formula is a relational expression of the Tg of a copolymer and the glass transition temperature Tgi of a homopolymer obtained by polymerizing each monomer constituting the copolymer independently. 1/Tg＝Σ(Wi/Tgi) Furthermore, in the above-mentioned Fox formula, Tg represents the glass transition temperature of the copolymer (unit: K), Wi represents the weight fraction of monomer i in the copolymer (copolymerization ratio on a weight basis), and Tgi represents monomer i The glass transition temperature of the homopolymer (unit: K).

As the glass transition temperature of the homopolymer for calculating Tg, the value described in the known document was used. For example, regarding the monomers listed below, the following values are used for the glass transition temperature of the homopolymer of the monomers. 2-Ethylhexyl Acrylate -70℃ n-Butyl Acrylate -55℃ n-butyl methacrylate 20℃ Isostearyl Acrylate -18℃ Methyl methacrylate 105℃ Methyl acrylate 8℃ Cyclohexyl acrylate 15℃ N-vinyl-2-pyrrolidone 54℃ 2-Hydroxyethyl Acrylate -15℃ 4-Hydroxybutyl Acrylate -40℃ Dicyclopentyl methacrylate 175℃ Iso-Acrylic Acid 94℃ Acrylic 106℃ Methacrylic acid 228℃

Regarding the glass transition temperature of homopolymers of monomers other than those listed above, values described in "Polymer Handbook" (3rd edition, John Wiley & Sons, Inc., 1989) were used. When multiple values are described in this document, the highest value is adopted.

Regarding the monomer whose glass transition temperature of the homopolymer is not described in the above-mentioned Polymer Handbook, the value obtained by the following measurement method was used (see Japanese Patent Application Laid-Open No. 2007-51271). Specifically, 100 parts by weight of monomers, 0.2 parts by weight of azobisisobutyronitrile, and 200 parts by weight of ethyl acetate as a polymerization solvent were put into a reactor equipped with a thermometer, a stirrer, a nitrogen inlet pipe, and a reflux cooling pipe, Stirring was carried out for 1 hour while flowing nitrogen gas. After removing oxygen in the polymerization system in this way, the temperature was raised to 63° C., and the reaction was carried out for 10 hours. Then, it cooled to room temperature, and obtained the homopolymer solution of 33 weight% of solid content concentration. Next, this homopolymer solution was cast-coated on a release liner, and dried to prepare a test sample (sheet-shaped homopolymer) having a thickness of about 2 mm. The test sample was punched into a disc shape with a diameter of 7.9 mm, sandwiched between parallel plates, and a viscoelasticity testing machine (ARES, manufactured by Rheometrics Co., Ltd.) was used to apply a shear strain at a frequency of 1 Hz while placing it in a temperature range of -70 Viscoelasticity was measured by shear mode at ~150°C and a heating rate of 5°C/min, and the peak temperature of tanδ was set as the Tg of the homopolymer.

The polymer (such as acrylic polymer, typically acrylic polymer) contained in the adhesive layer disclosed herein is not particularly limited, and the preferred SP value is 23.0 (MJ/m ³ ) ^1/2 or less . An adhesive comprising a polymer having such an SP value can preferably realize an adhesive having sufficient adhesive strength and excellent water releasability by, for example, containing a water affinity agent described later. The above-mentioned SP value is more preferably 21.0 (MJ/m ³ ) ^1/2 or less (for example, 20.0 (MJ/m ³ ) ^1/2 or less). The lower limit of the above-mentioned SP value is not particularly limited, for example, it is about 10.0 (MJ/m ³ ) ^1/2 or more, and it is suitably about 15.0 (MJ/m ³ ) ^1/2 or more, preferably 18.0 (MJ/m 3 ) 1/2 or more. ³ ) More than ^1/2 .

Furthermore, the SP value of the above-mentioned polymer can be calculated according to Fedors [refer to "Polymer Engineering and Science (POLYMER ENG. &SCI.)", Vol. 14, No. 2 (1974), pp. 148-154] That is, the formula: SP value δ=(ΣΔe/ΣΔv) ^1/2 (In the above formula, Δe is the evaporation energy Δe of each atom or atomic group at 25°C, and Δv is the molar volume of each atom or atomic group at the same temperature ) Calculation. A polymer having the above-mentioned SP value can be obtained by appropriately determining the monomer composition based on the technical common sense of the industry.

The adhesive layer can be formed using an adhesive composition containing the above-mentioned monomer components in the form of a polymer, an unpolymerized (that is, an unreacted polymerizable functional group), or a mixture thereof. . The above-mentioned adhesive composition can be in the following various forms: a water-dispersed adhesive composition in which the adhesive (adhesive component) is dispersed in water, a solvent-based adhesive composition in which the adhesive is contained in an organic solvent, and An active energy ray-curable adhesive composition (such as a light-curable adhesive composition) prepared by hardening active energy rays such as ultraviolet rays or radiation to form an adhesive, which is applied in a heated and molten state and cooled to a room temperature A hot-melt adhesive composition, etc. that will form an adhesive when the temperature is near.

In the polymerization, a known or commonly used thermal polymerization initiator or photopolymerization initiator can be used depending on the polymerization method, the state of polymerization, and the like. Such a polymerization initiator can be used individually by 1 type or in combination of 2 or more types suitably.

The thermal polymerization initiator is not particularly limited. For example, azo-based polymerization initiators, peroxide-based initiators, redox-based initiators obtained by combining peroxides and reducing agents, substituted Ethane-based starter, etc. More specifically, for example, 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylpropionamidine) disulfate, 2,2'-azobis( 2-amidinopropane) dihydrochloride, 2,2'-azobis[2-(5-methyl-2-imidazolin-2-yl)propane] dihydrochloride, 2,2'- Azobis(N,N'-dimethyleneisobutylamidine), 2,2'-azobis[N-(2-carboxyethyl)-2-methylpropionamidine]hydrate and other azo series Initiators; such as persulfates such as potassium persulfate and ammonium persulfate; peroxide-based initiators such as benzoyl peroxide, tertiary butyl hydroperoxide, and hydrogen peroxide; such as phenyl substituted ethane, etc. Substituted ethane-based initiators; redox-based initiators such as combinations of persulfate and sodium bisulfite, combinations of peroxide and sodium ascorbate, etc., but are not limited to these. In addition, thermal polymerization can be implemented preferably at the temperature of about 20-100 degreeC (typically, 40-80 degreeC), for example.

系光聚合起始劑等。The photopolymerization initiator is not particularly limited, and for example, ketal-based photopolymerization initiators, acetophenone-based photopolymerization initiators, benzoin ether-based photopolymerization initiators, acylphosphine oxide-based photopolymerization initiators, etc. Initiator, α-keto alcohol photopolymerization initiator, aromatic sulfonyl chloride photopolymerization initiator, photoactive oxime photopolymerization initiator, benzoin photopolymerization initiator, benzoyl photopolymerization initiator Polymerization initiator, benzophenone-based photopolymerization initiator, 9-oxosulfur

Department of photopolymerization initiator, etc.

The usage-amount of such a thermal-polymerization initiator or a photopolymerization initiator can be made into the usual usage-amount corresponding to a polymerization method, a polymerization form, etc., and it does not specifically limit. For example, about 0.001 to 5 parts by weight (typically, about 0.01 to 2 parts by weight, for example, about 0.01 to 1 part by weight) of the polymerization initiator can be used with respect to 100 parts by weight of monomers to be polymerized.

In the above polymerization, various previously known chain transfer agents (also known as molecular weight regulators or polymerization degree regulators) may be used as needed. As the chain transfer agent, mercaptans such as n-dodecyl mercaptan, tert-dodecyl mercaptan, and thioglycolic acid can be used. Alternatively, chain transfer agents containing no sulfur atoms (non-sulfur-based chain transfer agents) can also be used. Specific examples of non-sulfur-based chain transfer agents include: anilines such as N,N-dimethylaniline and N,N-diethylaniline; terpenes such as α-pinene and terpinolene; - Styrenes such as methyl styrene and α-methyl styrene dimer; compounds with benzylidene groups such as dibenzylidene acetone, cinnamyl alcohol, and cinnamaldehyde; p-phenylene such as hydroquinone and dihydroxynaphthalene Diphenols; quinones such as benzoquinone and naphthoquinone; olefins such as 2,3-dimethyl-2-butene and 1,5-cyclooctadiene; alcohols such as phenol, benzyl alcohol and allyl alcohol; Benzyl hydrogens such as diphenylbenzene and triphenylbenzene, etc. A chain transfer agent can be used individually by 1 type or in combination of 2 or more types. When using a chain transfer agent, the usage-amount can be about 0.01-1 weight part with respect to 100 weight part of monomer components, for example. The techniques disclosed herein can also be advantageously practiced without the use of chain transfer agents.

The molecular weight of polymers (for example, acrylic polymers, typically acrylic polymers) obtained suitably by the above-mentioned various polymerization methods is not particularly limited, and can be set in an appropriate range according to required performance and the like. The weight average molecular weight (Mw) of the above-mentioned polymer is suitably not less than about 10×10 ⁴ , for example, not less than about 15×10 ⁴ . By using a polymer (such as an acrylic polymer) having a Mw of a specific value or more, it is possible to achieve a well-balanced cohesive force and adhesive force. In some aspects, from the viewpoint of obtaining good adhesion reliability, the above-mentioned Mw may be 20×10 ⁴ or more, may be 30×10 ⁴ or more (for example, more than 30×10 ⁴ ), may be about 40 ×10 ⁴ or more, may be about 50×10 ⁴ or more, for example, may be about 55×10 ⁴ or more. The upper limit of the Mw of the polymer is not particularly limited, and may be, for example, about 500×10 ⁴ or less (for example, about 150×10 ⁴ or less), or about 75×10 ⁴ or less. In some preferred aspects, the above-mentioned Mw may be less than 50×10 ⁴ , less than 40×10 ⁴ , or less than 35×10 ⁴ (for example, less than 30×10 ⁴ ). Depending on the polymer having such a Mw, it tends to be easy to adjust the 60° C. loss elastic modulus of the adhesive to a specific range. Here, Mw refers to a value in terms of standard polystyrene obtained by gel permeation chromatography (GPC). As the GPC apparatus, for example, a model name "HLC-8320GPC" (column: TSKgelGMH-H(S), manufactured by Tosoh Corporation) may be used. The same applies to Examples described later.

The surface protection sheet of several aspects has the adhesive layer which consists of a water dispersion type adhesive composition. As a representative example of the water dispersion type adhesive composition, an emulsion type adhesive composition is mentioned. An emulsion-type adhesive composition typically contains a polymer as a monomer component, and additives used as needed.

Emulsion polymerization of monomer components is usually carried out in the presence of emulsifiers. The emulsifier used for emulsion polymerization is not particularly limited, and known anionic emulsifiers, nonionic emulsifiers, and the like can be used. An emulsifier can be used individually by 1 type or in combination of 2 or more types.

Non-limiting examples of anionic emulsifiers include: sodium lauryl sulfate, ammonium lauryl sulfate, sodium dodecylbenzenesulfonate, polyoxyethylene sodium lauryl sulfate, polyoxyethylene alkyl ether sulfuric acid Sodium, ammonium polyoxyethylene alkylphenyl ether sulfate, sodium polyoxyethylene alkylphenyl ether sulfate, sodium polyoxyethylene alkyl sulfosuccinate, etc. Non-limiting examples of nonionic emulsifiers include polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene fatty acid esters, polyoxyethylene polyoxypropylene block polymers, etc. . It is also possible to use emulsifiers which have reactive functional groups (reactive emulsifiers). Examples of reactive emulsifiers include radically polymerizable emulsifiers in which radically polymerizable functional groups such as propenyl groups and allyl ether groups are introduced into the above-mentioned anionic emulsifiers or nonionic emulsifiers. agent.

The usage-amount of the emulsifier in emulsion polymerization is 0.2 weight part or more, 0.5 weight part or more, 1.0 weight part or more, or 1.5 weight part or more with respect to 100 weight part of monomer components. Also, from the viewpoint of suppressing the decrease in adhesive force after warm water immersion, in some aspects, the usage-amount of the emulsifier is suitably 10 parts by weight or less, preferably 5 parts by weight, relative to 100 parts by weight of the monomer component. It may be less than or equal to 3 parts by weight. Furthermore, the emulsifier used for emulsion polymerization here can also function as a water affinity agent for the adhesive layer.

According to the emulsion polymerization, a polymerization reaction liquid in the form of an emulsion in which the polymer of the monomer component is dispersed in water can be obtained. The water-dispersed adhesive composition for forming the adhesive layer can be preferably produced using the above-mentioned polymerization reaction solution.

In some preferred aspects, the surface protection sheet has an adhesive layer formed from a solvent-based adhesive composition. A solvent-based adhesive composition typically contains a solution polymer of a monomer component, and optionally, additives. The effects brought about by the technology disclosed herein can also be effectively exerted in the form having a solvent-based adhesive layer. The solvent used for solution polymerization (polymerization solvent) can be suitably selected from conventionally known organic solvents. For example, aromatic compounds (typically aromatic hydrocarbons) selected from toluene and the like; esters such as ethyl acetate or butyl acetate; aliphatic or alicyclic hydrocarbons such as hexane or cyclohexane; Halogenated alkanes such as 1,2-dichloroethane; lower alcohols such as isopropanol (such as monohydric alcohols with 1 to 4 carbon atoms); ethers such as tertiary butyl methyl ether; ketones such as methyl ethyl ketone Any one solvent or a mixture of two or more solvents. According to the solution polymerization, a polymerization reaction liquid in which the polymer of the monomer component is dissolved in the polymerization solvent can be obtained. The solvent-based adhesive composition for forming the adhesive layer can be produced preferably using the above-mentioned polymerization reaction solution.

In another preferred aspect, the surface protection sheet has an adhesive layer formed of an active energy ray-curable adhesive composition. Here, in this specification, the term "active energy ray" refers to an energy ray having energy capable of causing chemical reactions such as polymerization reaction, crosslinking reaction, and decomposition of an initiator. Examples of the so-called active energy rays here include light such as ultraviolet rays, visible rays, and infrared rays, or radiation rays such as α-rays, β-rays, γ-rays, electron beams, neutron beams, and X-rays. A photocurable adhesive composition may be mentioned as a preferable example of the active energy ray-curable adhesive composition. The photocurable adhesive composition has an advantage that even a thick adhesive layer can be easily formed. Among them, an ultraviolet curable adhesive composition is preferable. In addition, the effects brought about by the technology disclosed herein can also be effectively exhibited in a form having a photocurable adhesive layer.

The photocurable adhesive composition typically contains at least a part of the monomer components of the composition in the form of a polymer (it may be part of the type of monomer or part of the weight). The polymerization method for forming the above-mentioned polymer is not particularly limited, and various known polymerization methods can be suitably used. For example, thermal polymerization such as solution polymerization, emulsion polymerization, and block polymerization (typically, carried out in the presence of a thermal polymerization initiator); photopolymerization by irradiating light such as ultraviolet rays (typically, carried out in the presence of in the presence of a polymerization initiator); radiation polymerization by irradiating radiation such as β-rays and γ-rays, etc. Among them, photopolymerization is preferable.

Some preferred aspects of the photocurable adhesive composition include a partial polymer of the monomer component. Such a partial polymer is typically a mixture of a polymer derived from a monomer component and an unreacted monomer, and is preferably in a slurry state (viscous liquid state). Hereinafter, some polymers with the above properties may be referred to as "monomer syrup" or simply "slurry". The polymerization method for partially polymerizing the monomer components is not particularly limited, and various polymerization methods as described above can be appropriately selected and used. From the standpoint of efficiency or simplicity, photopolymerization can be preferably employed. According to photopolymerization, the polymerization conversion rate (monomer conversion rate) of a monomer component can be easily controlled by polymerization conditions, such as the irradiation amount (light amount) of light.

The polymerization conversion rate of the monomer mixture in the above partial polymer is not particularly limited. The above-mentioned polymerization conversion rate can be set at, for example, about 70% by weight or less, preferably about 60% by weight or less. From the viewpoints of easiness of preparation or coatability of the adhesive composition containing the above-mentioned partial polymer, the above-mentioned polymerization conversion rate is suitably about 50% by weight or less, preferably about 40% by weight or less (for example, about 35% by weight or less). the following). The lower limit of the polymerization conversion rate is not particularly limited, but is typically at least about 1% by weight, and is suitably at least about 5% by weight.

Adhesive compositions comprising partial polymers of monomer components can be prepared, for example, by subjecting a monomer mixture comprising the entire amount of monomer components used to prepare the adhesive composition to a suitable polymerization method such as photopolymerization. Obtained by partial polymerization. In addition, the adhesive composition comprising a partial polymer of monomer components may be a partial polymer or a complete polymer of a monomer mixture comprising a part of the monomer components used to prepare the adhesive composition, and the remaining A mixture of monomer components or part of their polymers. Furthermore, in this specification, the term "complete polymer" means that the polymerization conversion rate exceeds 95% by weight.

Other components (such as photopolymerization initiators, multifunctional monomers, crosslinking agents, water affinity agents, etc.) can be formulated as needed in the adhesive composition containing the above-mentioned partial polymers. The method of compounding such other components is not specifically limited, For example, it may be contained in the said monomer mixture beforehand, or may be added to the said partial polymer.

(water affinity agent) A water affinity agent may be contained in an adhesive layer as needed. By making the adhesive layer contain a water affinity agent, the peeling force can be effectively reduced by using an aqueous liquid such as water. The reason is not particularly limited and explained, but it is generally believed that the water affinity agent is easily concentrated on the surface of the adhesive layer by having a hydrophilic region, so as to effectively improve the water affinity of the surface of the adhesive layer. Function, the adhesive layer effectively reduces the peeling force when in contact with water. A water affinity agent can be used individually by 1 type or in combination of 2 or more types.

In some aspects, at least one compound A selected from surfactants and compounds having a polyoxyalkylene skeleton can be used as a water affinity agent. As the surfactant and the compound having a polyoxyalkylene skeleton, one or more kinds of known surfactants and compounds having a polyoxyalkylene skeleton can be used without particular limitation. Furthermore, among the above-mentioned surfactants, there are compounds having a polyoxyalkylene skeleton, and of course vice versa.

As the surfactant that can be used as the compound A, known nonionic surfactants, anionic surfactants, cationic surfactants, and the like can be used. Among these, nonionic surfactants are preferred. Surfactants can be used individually by 1 type or in combination of 2 or more types.

Examples of nonionic surfactants include polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, and polyoxyethylene oleyl ether; polyoxyethylene Polyoxyethylene alkylphenyl ethers such as octylphenyl ether and polyoxyethylene nonylphenyl ether; sorbitan monocinnamate, sorbitan monopalmitate, sorbitan monostearate, sorbitan Sorbitan fatty acid esters such as alcohol anhydride monooleate; polyoxyethylene sorbitan monocinnamate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan monostearate, Polyoxyethylene sorbitan such as ethylene sorbitan tristearate, polyoxyethylene sorbitan triisostearate, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan trioleate, etc. Anhydride fatty acid ester; polyoxyethylene glyceryl ether fatty acid ester; polyoxyethylene-polyoxypropylene block copolymer, etc. These nonionic surfactants may be used alone or in combination of two or more.

Examples of anionic surfactants include alkylbenzenesulfonates such as nonylbenzenesulfonate and dodecylbenzenesulfonate (such as sodium dodecylbenzenesulfonate); Salt (such as sodium lauryl sulfate, ammonium lauryl sulfate), alkyl sulfate such as stearyl sulfate; fatty acid salt; polyoxyethylene stearyl ether sulfate, polyoxyethylene lauryl ether sulfate, etc. Ethylene alkyl ether sulfate (such as polyoxyethylene alkyl ether sulfate sodium), polyoxyethylene lauryl phenyl ether sulfate, etc. Polyoxyethylene alkyl phenyl ether sulfate (such as polyoxyethylene alkyl phenyl ether sulfate Ammonium, sodium polyoxyethylene alkylphenyl ether sulfate, etc.), polyether sulfates such as polyoxyethylene styrenated phenyl ether sulfate; polyoxyethylene stearyl ether phosphate, polyoxyethylene lauryl ether phosphate, etc. Oxyethylene alkyl ether phosphates; polyoxyethylene alkyl ether phosphates such as sodium salts and potassium salts of the above-mentioned polyoxyethylene alkyl ether phosphates; lauryl sulfosuccinate, polyoxyethylene lauryl sulfosuccinate sulfosuccinates such as sodium polyoxyethylene alkyl sulfosuccinates; polyoxyethylene alkyl ether acetates, etc. When the anionic surfactant forms a salt, the salt can be, for example, metal salts (preferably monovalent metal salts), ammonium salts, amine salts, etc. such as sodium salts, potassium salts, calcium salts, and magnesium salts. Anionic surfactants can be used individually by 1 type or in combination of 2 or more types.

In some aspects, for example, an anionic surfactant having at least one of -POH group, -COH group and -SOH group can be preferably used. Among them, a surfactant having a -POH group is preferred. Such surfactants typically include a phosphoric acid ester structure, such as a monoester of phosphoric acid (ROP(=O)(OH) ₂ ; here, R is a monovalent organic group), a diester ((RO) ₂ P (=O)OH; here, R is the same or different monovalent organic groups), a mixture including both monoester and diester, and the like. A preferable example of the surfactant having a -POH group may, for example, be polyoxyethylene alkyl ether phosphate. The number of carbon atoms in the alkyl group in the polyoxyethylene alkyl ether phosphate can be, for example, 6-20, 8-20, 10-20, 12-20, or 14-20 .

Examples of cationic surfactants include polyetheramines such as polyoxyethylene laurylamine and polyoxyethylene stearylamine. The cationic surfactant may be used alone or in combination of two or more.

As a compound having a polyoxyalkylene skeleton that can be used as compound A, for example, polyalkylene glycols such as polyethylene glycol (PEG) and polypropylene glycol (PPG); Ethers, polyethers comprising polyoxypropylene units, compounds comprising oxyethylene units and oxypropylene units (these units may be arranged randomly or in blocks); derivatives thereof things etc. Moreover, the compound which has a polyoxyalkylene skeleton among the said surfactants can also be used. These can be used individually by 1 type or in combination of 2 or more types. Among them, it is preferable to use a compound containing a polyoxyethylene skeleton (also called a polyoxyethylene segment), more preferably PEG.

The molecular weight (chemical formula weight) of the compound having a polyoxyalkylene skeleton (such as polyethylene glycol) is not particularly limited, for example, it is suitably less than 1000, and it is preferably about Below 600 (for example, below 500). The lower limit of the molecular weight of the compound having a polyoxyalkylene skeleton (such as polyethylene glycol) is not particularly limited, and those having a molecular weight of about 100 or more (for example, about 200 or more, further about 300 or more) can be preferably used.

As other examples of the water affinity agent, water-soluble polymers such as polyvinyl alcohol, polyvinylpyrrolidone, and polyacrylic acid may be mentioned. A water-soluble polymer can be used individually by 1 type or in combination of 2 or more types. In the technology disclosed herein, as the water affinity agent, one or two or more compounds A may be used, and one or two or more water-soluble polymers may be used, or they may be used in combination.

The HLB of the water affinity agent is not particularly limited, for example, it is 3 or more, suitably about 6 or more, and may be 8 or more (for example, 9 or more). In some preferred aspects, the HLB of the water affinity agent is 10 or more. Thereby, there exists a tendency for water releasability to be exhibited preferably. The above-mentioned HLB is more preferably 11 or more, further preferably 12 or more, and particularly preferably 13 or more (for example, 14 or more). Water releasability can be expressed more effectively by making the adhesive agent layer contain the water-affinity agent (typically, surfactant) which has HLB of the said range. The upper limit of the said HLB is 20 or less, for example, it may be 18 or less, 16 or less, or 15 or less.

Furthermore, the HLB in this specification is based on Griffin's Hydrophile-Lipophile Balance, which is a value representing the degree of affinity between a surfactant and water or oil, and is a value between 0 and 20 Indicates the ratio of hydrophilicity to lipophilicity. The definition of HLB is such as W. C. Griffin: J. Soc. Cosmetic Chemists, 1,311 (1949), or "Surfactant Handbook" co-authored by Takahashi Etsumin, Namba Yoshiro, Koike Jisheng, and Kobayashi Masao, 3rd edition, engineering books Published by Japan Press, November 25, 1972, pages 179-182, etc. The water affinity agent having the above-mentioned HLB may be selected based on the technical common sense of the industry with reference to the above-mentioned references and the like as necessary.

Such a water affinity agent is preferably contained in the adhesive layer in a free form. As a water-affinity agent, it is preferable to use what is liquid at normal temperature (about 25 degreeC) from the aspect of the preparation of an adhesive composition.

Typically, the adhesive layer containing a water-affinity agent is formed from an adhesive composition containing a water-affinity agent. The above-mentioned adhesive composition may be any one of the above-mentioned water-dispersed adhesive composition, solvent-based adhesive composition, active energy ray-curable adhesive composition, hot-melt adhesive composition, and the like. In some preferred aspects, the adhesive layer containing the water affinity agent may be an adhesive layer formed from a photocurable or solvent-based adhesive composition. In this kind of adhesive layer, the effect of adding the water affinity agent can be better exerted. The adhesive layer may also have photocurability.

The content of the water-affinity agent in the adhesive layer is not particularly limited, and can be set so that the use effect of the water-affinity agent can be appropriately exerted. In some aspects, the content of the water affinity agent can be set to 0.001 parts by weight or more per 100 parts by weight of monomer components constituting the polymer (such as acrylic polymer) contained in the adhesive layer, and can be set appropriately. It may be 0.01 weight part or more, may be 0.03 weight part or more, may be 0.07 weight part or more, and may be 0.1 weight part or more. In some preferred aspects, the content of the water affinity agent can be more than 0.2 parts by weight with respect to 100 parts by weight of the monomer components, for example, it can be more than 0.3 parts by weight from the viewpoint of obtaining a higher effect, or it can be It may be 0.4 weight part or more, may be 0.5 weight part or more, may be 1.0 weight part or more, and may be 1.5 weight part or more. Also, from the viewpoint of suppressing excessive diffusion of water to the entire adhesive layer, in some aspects, the amount of the water affinity agent used is, for example, 20 parts by weight or less with respect to 100 parts by weight of the monomer component, and is suitably set to 10 parts by weight. It is preferably at most 5 parts by weight, and may be at most 3 parts by weight. It is also preferable that the content of the water-affinity agent is not too large from the viewpoint of suppressing a decrease in the adhesive force when it comes into contact with an aqueous liquid, such as immersion in warm water. For example, in some aspects, the content of the water affinity agent may be less than 2 parts by weight, or less than 1 part by weight, or less than 0.7 parts by weight, or less than 0.7 parts by weight, relative to 100 parts by weight of the monomer components. It may be less than 0.3 weight part, and may be less than 0.2 weight part. A water affinity agent whose HLB is 10 or more tends to exhibit good water releasability even when used in a small amount.

(crosslinking agent) The adhesive composition disclosed herein is mainly for the purpose of cross-linking in the adhesive layer or cross-linking the adhesive layer and its adjacent surface, and may contain a cross-linking agent if necessary. Typically, the crosslinking agent is contained in the adhesive layer in the form after a crosslinking reaction. By using a crosslinking agent, the cohesion of the adhesive layer can be properly adjusted.

The type of cross-linking agent is not particularly limited, and can be selected from previously known cross-linking agents, for example, according to the composition of the adhesive composition, so that the cross-linking agent can perform a proper cross-linking function in the adhesive layer. Examples of usable crosslinking agents include: isocyanate-based crosslinking agents, epoxy-based crosslinking agents, oxazoline-based crosslinking agents, aziridine-based crosslinking agents, carbodiimide-based crosslinking agents, Melamine-based cross-linking agents, urea-based cross-linking agents, metal alkoxide-based cross-linking agents, metal chelate-based cross-linking agents, metal salt-based cross-linking agents, hydrazine-based cross-linking agents, amine-based cross-linking agents, etc. These can be used individually by 1 type or in combination of 2 or more types. In the water-dispersed adhesive composition, it is preferable to use a crosslinking agent that is soluble or dispersible in water.

As the isocyanate-based crosslinking agent, a difunctional or more polyfunctional isocyanate compound can be used. For example, aromatic isocyanates such as toluene diisocyanate, xylene diisocyanate, polymethylene polyphenyl diisocyanate, tris(p-isocyanatophenyl)phosphorothioate, and diphenylmethane diisocyanate; Alicyclic isocyanate such as phorone diisocyanate; Aliphatic isocyanate such as hexamethylene diisocyanate, etc. Examples of commercially available products include trimethylolpropane/toluene diisocyanate trimer adduct (manufactured by Tosoh Corporation, trade name "Coronate L"), trimethylolpropane/hexamethylene diisocyanate tripolymer Polymer adduct (manufactured by Tosoh Corporation, trade name "Coronate HL"), hexamethylene diisocyanate isocyanurate (manufactured by Tosoh Corporation, trade name "Coronate HX"), trimethylolpropane / Isocyanate adducts such as xylylene diisocyanate adducts (manufactured by Mitsui Chemicals, trade name "Takenate D-110 N"), etc. In the water-dispersed adhesive composition, it is preferable to use an isocyanate-based crosslinking agent that can be dissolved or dispersed in water. For example, a water-soluble, water-dispersible or self-emulsifying isocyanate-based crosslinking agent can be preferably used. A so-called blocked isocyanate-type isocyanate-based crosslinking agent in which isocyanate groups are blocked can be preferably used.

As an epoxy-type crosslinking agent, what has 2 or more epoxy groups in 1 molecule can be used without particular limitation. Preferably, it is an epoxy-type crosslinking agent which has 3-5 epoxy groups in 1 molecule. Specific examples of epoxy-based crosslinking agents include: N,N,N',N'-tetraglycidyl m-xylylenediamine, 1,3-bis(N,N-diglycidylamine (methyl)cyclohexane, 1,6-hexanediol diglycidyl ether, polyethylene glycol diglycidyl ether, polyglycerol polyglycidyl ether, etc. Examples of commercially available epoxy-based crosslinking agents include: Mitsubishi Gas Chemical Co., Ltd., trade names "TETRAD-X", "TETRAD-C", DIC Corporation, trade names "Epiclon CR-5L", Nagase The trade name "DENACOL EX-512" manufactured by ChemteX Co., Ltd., the trade name "TEPIC-G" manufactured by Nissan Chemical Industries, Ltd., etc.

As the oxazoline-based crosslinking agent, those having one or more oxazoline groups in one molecule can be used without particular limitation. In the water-dispersed adhesive composition, it is preferable to use an oxazoline-based crosslinking agent that can be dissolved or dispersed in water. The oxazolinyl may be any of 2-oxazolinyl, 3-oxazolinyl, and 4-oxazolinyl. Generally, an oxazoline-based crosslinking agent having a 2-oxazoline group can be preferably used. For example, 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2- Addition-polymerizable oxazoles such as isopropenyl-2-oxazoline, 2-isopropenyl-4-methyl-2-oxazoline, 2-isopropenyl-5-ethyl-2-oxazoline, etc. A water-soluble copolymer or a water-dispersible copolymer obtained by copolymerizing oxazoline with other monomers is used as an oxazoline-based crosslinking agent. As commercially available products of the oxazoline-based crosslinking agent, for example, "Epocros WS" series and "Epocros K" series manufactured by Nippon Shokubai Co., Ltd. may be mentioned.

Examples of aziridine-based crosslinking agents include trimethylolpropane tris[3-(1-aziridinyl)propionate], trimethylolpropane tris[3-(1-( 2-methyl) aziridinyl propionate)] and the like. As the carbodiimide-based crosslinking agent, a low-molecular compound or a high-molecular compound having two or more carbodiimide groups can be used.

In some aspects, peroxides may also be used as crosslinking agents. As the peroxide, for example: bis(2-ethylhexyl) peroxydicarbonate, bis(4-tert-butylcyclohexyl) peroxydicarbonate, di-second-butyl peroxydicarbonate, Tertiary butyl peroxyneodecanoate, third hexyl peroxypivalate, third butyl peroxypivalate, dilauroyl peroxide, dioctyl peroxide, isobutyric peroxide 1, 1,3,3-tetramethylbutyl ester, dibenzoyl peroxide, etc. Among these, peroxides particularly excellent in crosslinking reaction efficiency include: bis(4-tert-butylcyclohexyl)peroxydicarbonate, dilauroyl peroxide, and dibenzoyl peroxide. wait. Furthermore, when a peroxide is used as the above-mentioned polymerization initiator, the remaining peroxide which has not been used for the polymerization reaction can also be used for the crosslinking reaction. In this case, the remaining amount of the peroxide is quantified, and when the ratio of the peroxide is less than a specific amount, the peroxide may be added so that the specific amount may be obtained. Quantification of peroxide can be carried out by the method described in Japanese Patent No. 4971517.

The amount used when using a crosslinking agent (when two or more kinds of crosslinking agents are used, the total amount thereof) is not particularly limited. From the viewpoint of realizing an adhesive that exhibits well-balanced adhesive properties such as adhesive force or cohesion, the amount of the crosslinking agent used relative to the monomer components contained in the adhesive composition (for example, the monomer components of acrylic polymers) ) 100 parts by weight, for example, about 10 parts by weight or less, suitably set as less than 5 parts by weight, or less than 3 parts by weight, or less than 2 parts by weight, or less than 1 part by weight, or It may be less than 1 part by weight. In some aspects, the amount of the crosslinking agent (for example, an isocyanate-based crosslinking agent) relative to 100 parts by weight of the above-mentioned monomer components may be, for example, 0.50 parts by weight or less, or 0.40 parts by weight or less, or 0.40 parts by weight or less. 0.30 parts by weight or less, may be 0.20 parts by weight or less. The lower limit of the usage-amount of a crosslinking agent is not specifically limited, As long as it is more than 0 weight part with respect to 100 weight part of said monomer components. In some aspects, the usage-amount of a crosslinking agent can be 0.001 weight part or more with respect to 100 weight part of said monomer components, for example, can also be set as 0.01 weight part or more, also can be set as 0.05 weight part or more, or It can be set to 0.10 weight part or more. In some other aspects, the amount of the crosslinking agent used may be, for example, 0.5 parts by weight or more, 1 part by weight or more, or 1.5 parts by weight or more relative to 100 parts by weight of the above-mentioned monomer components.

Alternatively, it may be an adhesive composition that does not contain the above-mentioned crosslinking agent. When a photocurable adhesive composition is used as the adhesive composition disclosed herein, the adhesive composition may substantially not contain a crosslinking agent such as an isocyanate-based crosslinking agent. Here, the adhesive composition does not substantially contain a crosslinking agent (typically, an isocyanate-based crosslinking agent) means that the amount of the crosslinking agent is less than 0.05 parts by weight relative to 100 parts by weight of the above-mentioned monomer components (for example, less than 0.01 parts by weight).

In order to carry out the crosslinking reaction more efficiently, a crosslinking catalyst may also be used. Examples of the crosslinking catalyst include metal-based crosslinking catalysts such as tetra-n-butyl titanate, tetraisopropyl titanate, iron acetylacetonate, butyltin oxide, and dioctyltin dilaurate. Among them, tin-based crosslinking catalysts such as dioctyltin dilaurate are preferred. The usage amount of the cross-linking catalyst is not particularly limited. The amount of the crosslinking catalyst to be used can be set at about 0.0001 weight part or more, about 0.001 weight part or more with respect to 100 parts by weight of monomer components contained in the adhesive composition (for example, monomer components of acrylic polymers) , about 0.005 parts by weight or more, or about 1 part by weight or less, about 0.1 parts by weight or less, or about 0.05 parts by weight or less.

The adhesive composition for forming the adhesive layer may optionally contain a compound that causes keto-enol tautomerization as a crosslinking retarder. For example, in an adhesive composition containing an isocyanate-based crosslinking agent or an adhesive composition that can be formulated using an isocyanate-based crosslinking agent, a compound that produces keto-enol tautomerization can be preferably used. Thereby, the effect of prolonging the pot life of the adhesive composition can be exerted. As the compound causing keto-enol tautomerism, various β-dicarbonyl compounds can be used. Specific examples include: β-diketones such as acetylacetone and 2,4-hexanedione; acetylacetates such as methyl acetylacetate and ethyl acetylacetate; ethyl acetylacetate, etc. Propionyl acetates; isobutyryl acetates such as ethyl isobutyryl acetate; malonates such as methyl malonate and ethyl malonate, etc. Among them, acetylacetone and acetylacetate are exemplified as preferred compounds. The compounds causing keto-enol tautomerism can be used alone or in combination of two or more. The amount of the compound that produces keto-enol tautomerism is 0.1 to 20 parts by weight relative to 100 parts by weight of monomer components contained in the adhesive composition (for example, monomer components of acrylic polymers). The part or less is suitably set to 0.5 to 15 parts by weight, for example, 1 to 10 parts by weight, or 1 to 5 parts by weight.

(multifunctional monomer) A polyfunctional monomer may be used in an adhesive composition (and further an adhesive layer) as needed. Multifunctional monomers can be useful for purposes such as adjustment of cohesion. The polyfunctional monomer reacts the ethylenically unsaturated group above by light (such as ultraviolet light) irradiation when the adhesive layer is formed or attached to the adherend, thereby forming a cross-linked structure with moderate flexibility. Therefore, in this specification, "multifunctional monomer" can be renamed as a crosslinking agent. For example, a polyfunctional monomer can be preferably used in an adhesive layer formed from a photocurable adhesive composition. As a polyfunctional monomer, the compound which has 2 or more ethylenically unsaturated groups can be used. A polyfunctional monomer can be used individually by 1 type or in combination of 2 or more types.

Examples of the ethylenically unsaturated group in the polyfunctional monomer include, but are not limited to, an acryl group, a methacryl group, a vinyl group, and an allyl group. From the viewpoint of photoreactivity, an acryl group and a methacryl group are mentioned as a preferable ethylenically unsaturated group. Among them, an acryl group is preferred.

As a polyfunctional monomer, it is preferably a compound having 2 to 10 ethylenically unsaturated groups in the molecule, more preferably a compound having 2 to 8 ethylenically unsaturated groups in the molecule, and even more preferably a compound having 2 to 8 ethylenically unsaturated groups in the molecule. Compounds with 2 to 6 ethylenically unsaturated groups. In some aspects, as a multifunctional monomer, one having 4 or less (specifically 2 to 4, such as 2 or 3, preferably 2) ethylenically unsaturated groups in the molecule can be used. compound. By using the polyfunctional monomer whose number of ethylenically unsaturated groups is limited, it is easy to obtain an adhesive layer with both elongation and strength.

Examples of polyfunctional monomers include ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate Acrylates, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, ethylene glycol di(meth)acrylate ) acrylate, 1,6-hexanediol di(meth)acrylate, 1,12-dodecanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, four Methylolmethane tri(meth)acrylate, Allyl (meth)acrylate, Vinyl (meth)acrylate, Divinylbenzene, Epoxy acrylate, Polyester acrylate, Urethane acrylate ester, butanediol (meth)acrylate, hexanediol di(meth)acrylate, etc. Among them, trimethylolpropane tri(meth)acrylate, 1,6-hexanediol di(meth)acrylate, dipentaerythritol hexa(meth)acrylate are preferred, and 1,6- Hexylene glycol diacrylate.

The usage amount of the multifunctional monomer varies according to its molecular weight or functional group number, etc., for example, relative to the monomer component forming the polymer contained in the adhesive layer (typically, an acrylic polymer or a monomer of the polymer Component) is suitably in the range of about 0.01 to 3.0 parts by weight for 100 parts by weight. In some aspects, the usage amount of the multifunctional monomer relative to 100 parts by weight of the above-mentioned monomer components may be, for example, not less than 0.02 parts by weight, not less than 0.1 parts by weight, not less than 0.5 parts by weight, or not less than 1.0 parts by weight or more than 2.0 parts by weight. By increasing the amount of polyfunctional monomers used, higher cohesion tends to be obtained. On the other hand, from the viewpoint of avoiding the reduction of the adhesiveness of the layer adjacent to the adhesive layer due to an excessive increase in the cohesive force, the amount of the polyfunctional monomer relative to 100 parts by weight of the above-mentioned monomer components can be, for example, 10 parts by weight. It may be less than or equal to 5.0 parts by weight, or less than 3.0 parts by weight. In some aspects, the usage amount of the multifunctional monomer relative to 100 parts by weight of the above-mentioned monomer components is appropriately set to be 1.0 parts by weight or less, preferably 0.5 parts by weight or less, more preferably 0.3 parts by weight or less, or It is 0.2 weight part or less.

(adhesion imparting agent) In some preferred aspects, the adhesive layer contains an adhesive imparting agent. By including the tackifier in the adhesive layer, the peeling force at the starting point can be improved while maintaining the removability from the adherend by peeling with water. By using the water peeling technology disclosed in this article, adding an adhesion imparting agent as an adhesive force enhancing component, a high level of adhesion or edge peeling resistance and water peeling removability can be achieved at the time of protection. As the tackifier, various components that can improve the adhesive force can be used without any particular limitation. Preferable examples of the tackifier include tackifier resins and acrylic oligomers. The tackifier can be used alone or in combination of two or more.

Although it does not specifically limit, what provided the acid value can be used preferably as a tackiness imparting agent. By using an adhesion imparting agent having an acid value equal to or higher than a specific value, it is easy to obtain an effect of improving adhesion. For example, for the improvement of the adhesion of the polar adherend, the adhesion after warm water immersion can also be maintained at a high level. The acid value of the tackifier is, for example, more than 10 mgKOH/g, suitably more than 15 mgKOH/g, preferably more than 20 mgKOH/g, more preferably more than 23 mgKOH/g. The upper limit of the above-mentioned acid value is generally, for example, 200 mgKOH/g or less, and may be 100 mgKOH/g or less, 50 mgKOH/g or less, or 40 mgKOH/g or less from the viewpoint of water releasability. The acid value of the tackifier can be measured by the potentiometric titration method prescribed in JIS K 0070:1992.

In the form of using an adhesion-imparting agent, the usage-amount of an adhesion-imparting agent is not specifically limited. From the viewpoint of increasing the peeling force at the starting point, the amount of the tackifier used may be, for example, 0.1 parts by weight or more, or 0.3 parts by weight relative to 100 parts by weight of the monomer components constituting the polymer contained in the adhesive layer. 1 part by weight or more, may be 3 parts by weight or more, may be 5 parts by weight or more, and may be 10 parts by weight or more. In some preferred aspects, the amount of the adhesion-imparting agent relative to 100 parts by weight of the above-mentioned monomer components exceeds 10 parts by weight, may be more than 11 parts by weight, may be about 12 parts by weight, and is more preferably 15 parts by weight. More than 18 parts by weight, more preferably 18 parts by weight or more, especially 20 parts by weight or more (for example, 22 parts by weight or more), may be 25 parts by weight or more, may be 28 parts by weight or more, or may be 32 parts by weight The above may be 35 parts by weight or more. Moreover, the usage-amount of the tackiness imparting agent with respect to 100 weight part of said monomer components is suitably set as less than 100 weight part, for example, It may be about 80 weight part or less, It may be 70 weight part or less, It may be 50 weight part. servings or less. By limiting the usage amount of the tackifier to an appropriate range, the tackifier and the adhesive are well compatible, and the effect of adding the tackifier (adhesive properties such as adhesive force) can be easily and effectively exhibited. In some preferred aspects, the amount of the tack-imparting agent relative to 100 parts by weight of the above-mentioned monomer components is less than 50 parts by weight, more preferably less than 40 parts by weight, still more preferably less than 35 parts by weight, especially It is preferably not more than 32 parts by weight, may be not more than 30 parts by weight, and may be not more than 25 parts by weight. In some other aspects, the amount of the tack-imparting agent may be 20 parts by weight or less, less than 10 parts by weight, or less than 5 parts by weight relative to 100 parts by weight of the above-mentioned monomer components.

In the aspect of using the above-mentioned adhesion imparting agent, by using the adhesion imparting agent, the edge peeling resistance can be improved, so the use of the water-affinity agent, which may cause the decrease of the adhesion force when it is in contact with an aqueous liquid, is not limited amount, and then also increase the amount of water affinity agent. By using an adhesion imparting agent and a water affinity agent, a high level of adhesion and peeling and removability to the object to be protected can be achieved. In the aspect of using an adhesion imparting agent and a water affinity agent, the ratio (C _A /C _B ) of the water affinity amount (C _A ) contained in the adhesive layer to the adhesion imparting amount (C _B ) is not particularly limited. , for example, 0.0001 or more, suitably 0.001 or more, preferably 0.01 or more, more preferably 0.02 or more, still more preferably 0.03 or more, may be 0.05 or more, and may be 0.1 or more. By relatively increasing the usage amount of the water-affinity agent relative to the usage amount of the adhesion imparting agent, the adhesiveness based on the use of the adhesion imparting agent can be maintained within a specific range, and the water peeling force can be suppressed to be low, maintaining or improving the water peeling Removal. The upper limit of the above-mentioned ratio (C _A /C _B ) is not particularly limited, for example, it is 10 or less, suitably 1 or less, preferably 0.5 or less, more preferably 0.3 or less, may be less than 0.15, or less than 0.15. 0.1. By limiting the usage amount of the water-affinity agent to a specific range relative to the usage amount of the tackifier, the water releasability can be maintained and the adhesive force such as the starting point peeling force can be maintained or improved.

(acrylic oligomer) The pressure-sensitive adhesive layer disclosed herein may contain an acrylic oligomer from the viewpoint of improvement of cohesive force, improvement of adhesion with the base material layer, or improvement of adhesiveness with an adherend. According to the technology disclosed in this article, even if the surface protection sheet is attached to the object to be protected with a high adhesive force, when peeling off, it can be peeled off with water, and the surface protection sheet can be removed without damaging or deforming the object to be protected. Peel off. Therefore, it is possible to improve the adhesion reliability by including an adhesive force-improving component such as an acrylic oligomer in the adhesive, thereby improving the protection function. The adhesive layer containing an acrylic oligomer can be formed using the adhesive composition containing this acrylic oligomer. As the acrylic oligomer, one having a higher Tg than the Tg of the above-mentioned acrylic polymer (for example, acrylic polymer) can be preferably used.

Although Tg of the said acrylic oligomer is not specifically limited, For example, it may be about 20 degreeC or more and 300 degreeC or less. The above Tg may be, for example, about 30°C or higher, may be about 40°C or higher, may be about 60°C or higher, may be about 80°C or higher, or may be about 100°C or higher. When the Tg of the acrylic oligomer becomes higher, the effect of improving the cohesive force tends to be higher overall. In addition, from the viewpoint of the grip property to the substrate layer, impact absorption, etc., the Tg of the acrylic oligomer may be, for example, about 250°C or lower, about 200°C or lower, or about 180°C or lower. Or below about 150°C. In addition, Tg of an acrylic oligomer is the value calculated based on Fox's formula similarly to Tg of the said acrylic-type polymer.

The Mw of the acrylic oligomer is not particularly limited, and may be, for example, about 1000 or more, suitably about 1500 or more, may be about 2000 or more, and may be about 3000 or more. Moreover, the Mw of an acrylic oligomer may be less than about 30000, suitably less than about 10000, may be less than about 7000, and may be less than about 5000, for example. When Mw is within the above-mentioned range, the effect of improving the cohesiveness or adhesiveness of the adhesive layer is easily exhibited favorably. The Mw of the acrylic oligomer can be measured by GPC, and can be calculated|required as the value of standard polystyrene conversion. Specifically, for example, in HPLC8020 manufactured by Tosoh Corporation, TSKgelGMH-H (20)×2 columns are used, and the measurement is performed at a flow rate of about 0.5 mL/min using a tetrahydrofuran solvent.

As the monomer component constituting the acrylic oligomer, it can be exemplified: the above-mentioned various C _1-20 alkyl (meth)acrylates; the above-mentioned various alicyclic hydrocarbon group-containing (meth)acrylates; the above-mentioned Various (meth)acrylates containing aromatic hydrocarbon groups; (meth)acrylate monomers such as (meth)acrylates obtained from terpene compound derivative alcohols. These can be used individually by 1 type or in combination of 2 or more types.

From the viewpoint of improving adhesiveness, the acrylic oligomer preferably contains (meth)acrylic acid isobutyl (meth)acrylate or tertiary butyl (meth)acrylate with an alkyl group having a branched chain structure. Acrylic monomers with relatively large structures represented by alkyl acrylates, (meth)acrylates containing alicyclic hydrocarbon groups or (meth)acrylates containing aromatic hydrocarbon groups are used as monomers unit. Also, when ultraviolet rays are used in the synthesis of the acrylic oligomer or the preparation of the adhesive layer, a monomer having a saturated hydrocarbon group at the end of the ester is preferable because it is less likely to cause polymerization inhibition. It is preferable to use an alkyl (meth)acrylate having a branched chain structure in the alkyl group or a (meth)acrylate containing a saturated alicyclic hydrocarbon group.

The ratio of the (meth)acrylate monomer to the total monomer components constituting the acrylic oligomer is typically more than 50% by weight, preferably 60% by weight or more, more preferably 70% by weight or more ( For example, 80% by weight or more, further 90% by weight or more). In some preferred aspects, the acrylic oligomer has a monomer composition substantially including only one or two or more (meth)acrylate monomers. When the monomer component contains an alicyclic hydrocarbon group-containing (meth)acrylate and a C _1-20 alkyl (meth)acrylate, their weight ratio is not particularly limited. In some aspects, the weight ratio of (meth)acrylic acid ester/(meth)acrylic acid C _1-20 alkyl ester containing alicyclic hydrocarbon group can be set as 10/90 or more, 20/80 or more or 30/ 70 or more, and may be 90/10 or less, 80/20 or less, or 70/30 or less.

As the constituent monomer components of the acrylic oligomer, in addition to the above-mentioned (meth)acrylate monomers, functional group-containing monomers may be used as needed. As monomers containing functional groups, monomers with heterocyclic rings containing nitrogen atoms such as N-vinyl-2-pyrrolidone and N-acrylyl 𠰌line; (meth)acrylic acid N,N -Amino-containing monomers such as dimethylaminoethyl ester; N,N-diethyl(meth)acrylamide and other amide-containing monomers; AA, MAA and other carboxyl-containing monomers; ( Hydroxyl-containing monomers such as 2-hydroxyethyl methacrylate. These functional group-containing monomers may be used alone or in combination of two or more. In the case of using a functional group-containing monomer, the ratio of the functional group-containing monomer to the total monomer components constituting the acrylic oligomer can be, for example, 1% by weight or more, 2% by weight or more, or 3% by weight or more. % by weight or more, and, for example, 15% by weight or less, 10% by weight or less, or 7% by weight or less. The acrylic oligomer may not use a functional group-containing monomer.

As preferred acrylic oligomers, for example, dicyclopentyl methacrylate (DCPMA), cyclohexyl methacrylate (CHMA), iso-methacrylate (IBXMA), iso-methacrylate ester (IBXA), dicyclopentyl acrylate (DCPA), 1-adamantyl methacrylate (ADMA), homopolymers of 1-adamantyl acrylate (ADA), and copolymers of DCPMA and MMA , Copolymer of DCPMA and IBXMA, Copolymer of ADA and methyl methacrylate (MMA), Copolymer of CHMA and isobutyl methacrylate (IBMA), Copolymer of CHMA and IBXMA, CHMA and acryl Copolymer of phenoline (ACMO), copolymer of CHMA and diethylacrylamide (DEAA), copolymer of CHMA and AA, etc.

Acrylic oligomers can be formed by polymerizing their constituent monomer components. The polymerization method or polymerization form is not particularly limited, and various previously known polymerization methods (for example, solution polymerization, emulsion polymerization, block polymerization, photopolymerization, radiation polymerization, etc.) can be employed in an appropriate form. The kind of polymerization initiator (such as azo-type polymerization initiator) that can be used as needed is roughly as exemplified for the synthesis of acrylic polymers, and the amount of polymerization initiator or chain transfer agent (such as mercaptans) optionally used The amount is appropriately set based on common technical knowledge so as to obtain a desired molecular weight, and therefore detailed description is omitted.

When the acrylic oligomer is contained in the adhesive layer or the adhesive composition, its content is relative to 100 weight of monomer components of the polymer (typically, acrylic polymer) contained in the adhesive layer The part may be, for example, 0.01 part by weight or more, and may be 0.05 part by weight or more, or 0.1 part by weight or more, or 0.2 part by weight or more from the viewpoint of obtaining a higher effect. In some aspects, the content of the acrylic oligomer is suitably at least 0.5 parts by weight, preferably at least 1 part by weight, and may be at least 2 parts by weight with respect to 100 parts by weight of the above-mentioned monomer components. In addition, from the viewpoint of compatibility with the above-mentioned polymer (typically, an acrylic polymer), the content of the acrylic oligomer relative to 100 parts by weight of the above-mentioned monomer components is suitably set to less than 50 parts by weight. , preferably less than 30 parts by weight, more preferably less than 25 parts by weight, for example, less than 10 parts by weight, less than 5 parts by weight or less than 1 part by weight.

(adhesion imparting resin) The adhesive agent layer may also contain an adhesive agent resin. According to the technology disclosed in this article, even if the surface protection sheet is attached to the object to be protected with a high adhesive force, when peeling off, it can be peeled off with water, and the surface protection sheet can be removed without damaging or deforming the object to be protected. Peel off. Therefore, it is possible to improve the adhesion reliability by including an adhesion-improving component such as an adhesion-imparting resin in the adhesive, thereby improving the protection function. Examples of tackifying resins include rosin-based tackifying resins, rosin-derived tackifying resins, petroleum-based tackifying resins, terpene-based tackifying resins, phenol-based tackifying resins, and ketone-based tackifying resins. These can be used individually by 1 type or in combination of 2 or more types.

Examples of the above-mentioned rosin-based tackifying resin include rosins such as gum rosin, wood rosin, and tall oil rosin; Rosin (for example, a polymer of the above-mentioned rosin, typically a dimer), modified rosin (for example, modified by an unsaturated acid such as maleic acid, fumaric acid, (meth)acrylic acid, etc. Modified unsaturated acid modified rosin, etc.) etc. Examples of the above-mentioned rosin derivative tackifying resin include, for example, esterified products of the above-mentioned rosin-based tackifying resin (for example, rosin esters such as stabilized rosin esters and polymerized rosin esters), phenol-modified products of the above-mentioned rosin-based resins ( Phenol-modified rosin) and its esters (phenol-modified rosin ester), etc. Examples of the petroleum-based tackifying resin include aliphatic petroleum resins, aromatic petroleum resins, copolymer petroleum resins, alicyclic petroleum resins, and hydrogenated products thereof. Examples of the terpene-based tackifying resin include α-pinene resins, β-pinene resins, aromatic-modified terpene-based resins, and hydrogenated terpene resins. The above-mentioned terpene phenol resin refers to a polymer containing terpene residues and phenol residues, and its concept includes copolymers of terpenes and phenolic compounds (terpene-phenol copolymer resins), and homopolymerization of terpenes Both of those obtained by phenol modification (phenol-modified terpene resins) or copolymers. Terpene phenol resins include hydrogenated terpene phenol resins. As said phenolic tackifier resin, the alkylphenol resin obtained from alkylphenol and formaldehyde, etc. are mentioned. As an example of an alkylphenol resin, a novolak type and a resol type are mentioned. As the above-mentioned ketone-based tackifying resin, for example, use of ketones (for example, aliphatic ketones such as methyl ethyl ketone, methyl isobutyl ketone, and acetophenone; cyclohexanone, methylcyclohexanone, etc. Ketone-based resins obtained by condensation of alicyclic ketones, etc.) and formaldehyde.

In some aspects, as the tackifying resin, one or more kinds selected from the group consisting of rosin-based tackifying resins, rosin derivative tackifying resins, and terpene phenol resins can be preferably used. Among them, rosin derivative tack-imparting resins are preferred, and rosin esters such as stabilized rosin esters and polymerized rosin esters may, for example, be mentioned.

In the water-dispersed adhesive composition, it is preferable to use a water-dispersed tackifier resin in a form in which the aforementioned tackifier resin is dispersed in an aqueous solvent. For example, by mixing an aqueous dispersion of an acrylic polymer with a water-dispersed tackifier resin, an adhesive composition containing these components at a desired ratio can be easily prepared. In some aspects, as the water-dispersed tackifier resin, one that does not substantially contain at least an aromatic hydrocarbon-based solvent can be preferably used from the viewpoint of environmental sanitation. It is more preferable to use a water-dispersed tackifier resin that does not substantially contain aromatic hydrocarbon solvents and other organic solvents.

Examples of commercially available water-dispersed tackifying resins containing rosin esters include: "SUPER ESTER E-720", "SUPER ESTER E-730-55" and "SUPER ESTER E-730-55" manufactured by Arakawa Chemical Industry Co., Ltd. ESTER E-865NT", "SUPER ESTER NS", etc., or "HARIESTER SK-90D", "HARIESTER SK-70D", "HARIESTER SK-70E", "NEOTOL 115E", etc. manufactured by Harima Chemicals Co., Ltd. In addition, commercially available terpene phenol resins (which may be in the form of water-dispersible terpene phenol resins) include "TAMANOL E-100" and "TAMANOL E-200" manufactured by Arakawa Chemical Industry Co., Ltd. , "TAMANOL E-200NT", etc.

The softening point of the tack-imparting resin is not particularly limited. From a viewpoint of suppressing the fall of the cohesive force of an adhesive layer, it is preferable to use the tackiness imparting resin whose softening point is 80 degreeC or more. The softening point of the tackifying resin may be 90°C or higher, 100°C or higher, 110°C or higher, or 120°C or higher. Adhesion imparting resins with a softening point of 130°C or higher or 140°C or higher can also be used. In addition, from the viewpoint of adhesiveness to the base material layer, adhesiveness to an adherend, etc., it is preferable to use a tackifying resin having a softening point of 200° C. or lower or 180° C. or lower. In addition, as the softening point of the tackiness imparting resin so-called here, the nominal value described in a document, a catalog, etc. can be used. When there is no nominal value, the softening point of the tack-imparting resin can be measured based on the softening point test method (ring and ball method) stipulated in JIS K5902 or JIS K2207.

From the viewpoint of better exerting its use effect, the usage-amount of the tack-imparting resin is suitably set at 1 weight part or more with respect to 100 weight parts of monomer components constituting the polymer contained in the adhesive layer, and may be 5 parts by weight or more, and may be 10 parts by weight or more. In some preferred aspects, the amount of the tack-imparting resin relative to 100 parts by weight of the above-mentioned monomer components exceeds 10 parts by weight, more preferably 15 parts by weight or more, further preferably 18 parts by weight or more, and most preferably 20 parts by weight. More than 22 parts by weight, for example 22 parts by weight or more, 25 parts by weight or more, 28 parts by weight or more, 32 parts by weight or more, or 35 parts by weight or more. Also, from the viewpoint of well-balanced adhesion and cohesiveness to the base material layer or the adherend, the usage-amount of the tackiness-imparting resin relative to 100 parts by weight of the monomer component is suitably set to less than 100 parts by weight, for example. , may be less than 70 parts by weight, may be less than 50 parts by weight, may be less than 40 parts by weight, may be less than 30 parts by weight, may also be less than 20 parts by weight. By limiting the amount of the tackifying resin used to an appropriate range, the tackifying resin and the adhesive are compatible well, and the effect of adding the tackifying resin (adhesive properties such as adhesive force) can be effectively exhibited. Alternatively, it may be an adhesive layer that does not substantially contain an adhesive-imparting resin.

(silane coupling agent) In some aspects, the adhesive layer may contain a silane coupling agent. According to the adhesive layer containing the silane coupling agent, a surface protection sheet with high adhesive force can be preferably realized. A silane coupling agent can be used individually by 1 type or in combination of 2 or more types.

Examples of silane coupling agents include: 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2-(3,4-epoxycyclohexyl) Ethyltrimethoxysilane and other silicon compounds with epoxy structure; 3-aminopropyltrimethoxysilane, N-(2-aminoethyl) 3-aminopropyltrimethoxysilane, N-( 2-aminoethyl) 3-aminopropylmethyldimethoxysilane and other amino-containing silicon compounds; 3-chloropropyltrimethoxysilane; 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane and other silane coupling agents containing (meth)acrylyl; 3-isocyanatopropyl Isocyanate-containing silane coupling agents such as triethoxysilane, etc. Among them, 3-glycidoxypropyltrimethoxysilane and acetoacetyl group-containing trimethoxysilane can be mentioned as preferable examples.

The usage amount of the silane coupling agent can be set so as to obtain the desired usage effect, and is not particularly limited. In some aspects, the amount of the silane coupling agent used is, for example, 0.001 part by weight or more relative to 100 parts by weight of monomer components constituting the polymer contained in the adhesive layer, from the viewpoint of obtaining a higher effect , may be 0.005 parts by weight or more, may be 0.01 parts by weight or more, and may be 0.015 parts by weight or more. Also, from the viewpoint of improving adhesiveness, in some aspects, the amount of the silane coupling agent used may be, for example, 3 parts by weight or less, or 1 part by weight relative to 100 parts by weight of the monomer components constituting the adhesive layer. part or less, or 0.5 part by weight or less. Also, the technology disclosed herein can be implemented in an aspect using an adhesive composition that does not substantially contain a silane coupling agent. By restricting the use of silane coupling agents or not using silane coupling agents, the increase in adhesive force over time can be suppressed, and good water releasability can be easily obtained.

Furthermore, in the aspect where the monomer component contains an alkoxysilyl group-containing monomer, the aforementioned alkoxysilyl group-containing monomer can also be used as part or all of the silane coupling agent contained in the adhesive layer. .

系光聚合起始劑等。光聚合起始劑可單獨使用1種或適宜組合使用2種以上。 (Photopolymerization Initiator) The adhesive composition and photocurable adhesive layer disclosed herein may optionally contain a photopolymerization initiator (also called a photoreaction catalyst) for the purpose of imparting photocurability, etc. ). As the photopolymerization initiator, ketal-based photopolymerization initiators, acetophenone-based photopolymerization initiators, benzoin Ether-based photopolymerization initiators, acyl phosphine oxide-based photopolymerization initiators, α-keto alcohol-based photopolymerization initiators, aromatic sulfonyl chloride-based photopolymerization initiators, photoactive oxime-based photopolymerization initiators agent, benzoin-based photopolymerization initiator, benzoyl-based photopolymerization initiator, benzophenone-based photopolymerization initiator, 9-oxosulfur

Department of photopolymerization initiator, etc. A photoinitiator can be used individually by 1 type or in combination of 2 or more types suitably.

The content of the photopolymerization initiator in the adhesive layer is not particularly limited, and can be set so that desired effects can be appropriately exhibited. In some aspects, the content of the photopolymerization initiator can be set to about 0.005 parts by weight relative to 100 parts by weight of monomer components of the polymer (typically, acrylic polymer) contained in the adhesive layer. The above is suitably set to 0.01 parts by weight or more, preferably 0.05 parts by weight or more, may be 0.10 parts by weight or more, may be 0.15 parts by weight or more, and may be 0.20 parts by weight or more. By increasing the content of the photopolymerization initiator, the photohardenability of the adhesive layer is improved. Also, the content of the photopolymerization initiator relative to 100 parts by weight of the above-mentioned monomer components is suitably set to 5 parts by weight or less, preferably 2 parts by weight or less, may be 1 part by weight or less, or may be set to 0.7 parts by weight or less, may be 0.5 parts by weight or less. It may become advantageous from the viewpoint of improvement of the storage stability (for example, stability with respect to photodegradation) of a surface protection sheet that the content of a photoinitiator is not too much.

Typically, the adhesive layer containing a photoinitiator can be formed using the adhesive composition (for example, a solvent type adhesive composition) containing this photoinitiator. The adhesive composition containing a photoinitiator can be prepared, for example by mixing other components used in this composition with a photoinitiator. In addition, in the case of preparing an adhesive composition using a polymer (typically, an acrylic polymer) synthesized (photopolymerized) in the presence of a photopolymerization initiator, it is also possible to utilize the The residue (unreacted matter) of the photopolymerization initiator used is used as a part or all of the photopolymerization initiator contained in the adhesive layer. The same applies to the case of using one synthesized in the presence of a photopolymerization initiator as an optionally used acrylic oligomer. From the viewpoint of ease of production management, the adhesive layer disclosed herein can be preferably formed using an adhesive composition prepared by newly adding the above-mentioned amount of photopolymerization initiator to other constituents.

(other ingredients) The adhesive composition used for forming an adhesive layer may contain the acid or alkali (ammonia etc.) used for pH adjustment etc. as needed. Examples of other optional components that may be contained in the composition include viscosity modifiers (such as tackifiers), leveling agents, plasticizers, fillers, coloring agents such as pigments or dyes, stabilizers, preservatives, anti-corrosion agents, etc. Various additives commonly used in the field of adhesive compositions such as aging agents. Regarding such various additives, previously known ones can be used by conventional methods, and since they do not particularly characterize the present invention, detailed descriptions will be omitted. Furthermore, although there is no particular limitation, the technique disclosed herein can be preferably implemented in an aspect having an adhesive layer mainly composed of the above-mentioned polymer (such as an acrylic polymer). In some aspects, the ratio of the above-mentioned polymer (for example, acrylic polymer) in the above-mentioned adhesive layer is about 85% by weight or more (for example, 85-100% by weight), or 90% by weight or more, or It may be 95% by weight or more.

(Formation of Adhesive Layer) The adhesive layer may be a hardened layer of the adhesive composition. That is, the adhesive layer can be formed by applying (for example, applying) the adhesive composition to an appropriate surface, and then performing a hardening treatment as appropriate. When performing two or more types of hardening treatments (drying, crosslinking, polymerization, etc.), these may be performed simultaneously or through multiple stages. In an adhesive composition using a partial polymer (acrylic polymer syrup) of a monomer component, typically, the final copolymerization reaction is performed as the curing treatment described above. That is, part of the polymer is subjected to further copolymerization to form a complete polymer. For example, in the case of a photocurable adhesive composition, light irradiation is performed. Hardening treatments such as crosslinking and drying may also be performed as needed. For example, when drying with a photocurable adhesive composition is necessary, photocuring may be performed after drying. In an adhesive composition using a complete polymer, typically, drying (heat drying), crosslinking, and other treatments are performed as the above-mentioned hardening treatment, if necessary. The adhesive layer of a multi-layer structure of two or more layers can be produced by laminating pre-formed adhesive layers. Alternatively, the adhesive composition may be applied on the previously formed first adhesive layer, and the adhesive composition may be cured to form the second adhesive layer.

For the coating of the adhesive composition, for example, gravure roll coater, reverse roll coater, touch roll coater, dip roll coater, rod coater, knife coater, spray coater can be used Wait for the customary coating machine to implement. For example, as a method of providing an adhesive layer on a base layer, a direct method of directly applying an adhesive composition to the base layer to form an adhesive layer may be used, or an adhesive layer to be formed on a peeling surface may be used. Transfer printing to the substrate layer.

The thickness of the adhesive layer is not particularly limited, and may be, for example, about 3 μm to 1000 μm. From the viewpoint of making the adhesive layer adhere to the substrate layer or the adherend to improve water resistance reliability, in some aspects, the thickness of the adhesive layer is preferably 5 μm or more (for example, more than 5 μm), more preferably It is 10 μm or more (for example, more than 10 μm), more preferably 15 μm or more, particularly preferably 20 μm or more. The surface protection sheet disclosed in this paper has water releasability, and can be successfully peeled and removed from the adherend by using the water releasability. Therefore, the thickness of the adhesive layer can be increased, the adhesion such as the peeling force at the starting point can be increased, and the protection can be maintained or improved. sex. In addition, from the viewpoint of preventing paste residue due to coagulation and destruction of the adhesive layer, in some aspects, the thickness of the adhesive layer may be, for example, 500 μm or less, or may be 300 μm or less, or may be 200 μm or less. μm or less, or 150 μm or less. In some preferred aspects, the thickness of the adhesive layer is less than 100 μm, more preferably less than 60 μm, further preferably less than 50 μm, for example, may be less than 40 μm, or less than 30 μm. By limiting the thickness of the adhesive layer, water infiltration from the end of the adhesive layer can be restricted, and the reduction of the adhesive force in the state of immersion in aqueous liquid or warm water can be suppressed. Furthermore, the adhesive layer may have a single-layer structure, or may have a multi-layer structure of two or more layers.

In some aspects, the loss elastic modulus G" at 60°C of the adhesive layer (60°C loss elastic modulus G") is preferably in the range of not less than 10 kPa and not more than 50 kPa. According to the surface protection sheet having the adhesive layer having the 60°C loss elastic modulus G" in the above range, the hot water resistance is improved based on the viscosity of the adhesive (60°C loss elastic modulus G"), for example, even When used in liquid medicine (typically, in the form of an aqueous solution) or warm water, it is also easy to maintain an adherent state with respect to the adherend, and does not show or suppress the decrease in adhesive force due to water peelability. Therefore, even when the object to be protected is treated in a liquid with the surface protection sheet attached to the object to be protected, the adhesiveness required for protection can be preferably maintained. In addition, when a peeling load is applied to the end of the surface protection sheet due to the expansion and contraction of the base layer in warm water, the peeling load is converted into heat energy in an adhesive having a specific viscosity term at 60°C. It is lightened, so it is easy to maintain a stable bonding state. Such a surface protection sheet can be, for example, excellent in protective properties that do not cause peeling from the edges during the above-mentioned submerged liquid treatment.

In some preferred aspects, from the viewpoint of adhesiveness after immersion in the chemical solution or warm water, the 60°C loss elastic modulus G" of the above-mentioned adhesive layer is 12 kPa or more, more preferably 15 kPa or more, and also It can be above 18 kPa, above 22 kPa, above 25 kPa, above 28 kPa, above 30 kPa, or above 32 kPa. G" is set higher, and the adhesive force F1 can be maintained higher after 30 minutes of warm water immersion. In some aspects, the upper limit of the above-mentioned 60°C loss modulus of elasticity G" may be less than 45 kPa, or less than 40 kPa, or less than 35 kPa. By changing the 60°C loss modulus of elasticity of the adhesive layer to When G" is limited to a certain value or less, it is easy to obtain an adhesive having good adhesive properties suitable for surface protection applications. In some other aspects, the 60°C loss elastic modulus G" of the above-mentioned adhesive layer may be 30 kPa or less, 25 kPa or less, or 20 kPa or less.

More specifically, the 60°C loss elastic modulus G" of the above adhesive layer may be 11 kPa or less, 12 kPa or less, 13 kPa or less, 14 kPa or less, 15 kPa or less, 16 kPa or less, 17 kPa or less, 18 kPa or less, 19 kPa or less, 20 kPa or less, 21 kPa or less, 22 kPa or less, 23 kPa or less, 24 kPa Above or below, above or below 25 kPa, above or below 26 kPa, above or below 27 kPa, above or below 28 kPa, above or below 29 kPa or below, above or below 30 kPa, above or below 31 kPa, above or below 32 kPa Below, above or below 33 kPa, above or below 34 kPa, above or below 35 kPa, above or below 36 kPa, above or below 37 kPa, above or below 38 kPa, above or below 39 kPa, above or below 40 kPa, Above or below 41 kPa, above or below 42 kPa, above or below 43 kPa, above or below 44 kPa, above or below 45 kPa, above or below 46 kPa, above or below 47 kPa, above or below 48 kPa, 49 kPa above or below.

The above 60°C loss elastic modulus G" can be obtained mainly by adjusting the molecular weight or molecular weight distribution of the polymer contained in the adhesive. In addition, it can also be adjusted by the cross-linking density in the adhesive. Adhesive layer The 60°C loss elastic modulus G" can be measured by the method described in the examples described later.

(rebound resistance) Although not particularly limited, as the adhesive (layer), it is preferable to use an adhesive that is self-compression-bonded to the adherend in the rebound resistance test implemented in the method described in the examples described later. The peeling distance after 1 hour is 3.0 mm or less. The adhesive (layer) having such rebound resistance is less prone to end peeling from the adherend against the physical load (peeling load) in the thickness direction of the surface protection sheet having the adhesive (layer), thereby exhibiting excellent performance. Anti-end stripping. The above-mentioned peeling distance (after one hour from crimping) in the above-mentioned rebound resistance test is preferably at most 1.0 mm, more preferably at most 0.5 mm, still more preferably at most 0.3 mm, most preferably at most 0.2 mm, and most preferably at most 0.2 mm. is 0.0mm. The anti-rebound property mentioned above can be realized based on the composition of the adhesive (the use of the adhesive imparting agent or the selection of the type of the adhesive imparting agent, the type or amount of the water affinity agent, etc.).

＜Substrate layer＞ The surface protection sheet disclosed herein may include a substrate layer. As a non-limiting example of the material of the substrate layer, various resin films such as polyolefin film, polyester film, and polyvinyl chloride film; including polyurethane foam, polyethylene foam, polychloroprene film, etc. Foam sheets of foams such as olefin foam; single or blended spinning of various fibrous materials (natural fibers such as hemp and cotton, synthetic fibers such as polyester and vinylon, semi-synthetic fibers such as acetate, etc.) Woven and non-woven fabrics obtained from others; paper such as Japanese paper, wood paper, kraft paper, and crepe paper; metal foils such as aluminum foil, copper foil, and stainless steel (SUS), etc., which can be obtained from one or more than two types of composites. Select an appropriate material from the layered body of the composition and use it as the material of the base material layer. Examples of the substrate layer of the above-mentioned composite structure include laminated substrates (multilayer substrates) in which a metal foil and the above-mentioned resin film are laminated, resin sheets reinforced with inorganic fibers such as glass cloth, and the like.

As a material of the base layer, various films (hereinafter also referred to as base film) can be preferably used. The aforementioned base film may be a porous film such as a foam film or a nonwoven sheet, or may be a film having a laminated structure of a porous layer and a non-porous layer. In some aspects, as the above-mentioned base film, one including a (self-supporting or non-dependent) resin film capable of independently maintaining its shape can be preferably used as the base film. Here, the "resin film" means a non-porous structure, typically a resin film substantially free of bubbles (no voids). Therefore, the above-mentioned resin film is a concept different from a foam film or a nonwoven fabric. The above-mentioned resin film may have a single-layer structure, or may have a multi-layer structure of two or more layers (for example, a three-layer structure).

As the resin material constituting the resin film, for example, polyesters such as polyethylene terephthalate (PET) or polybutylene terephthalate (PBT), polyethylene naphthalate (PEN) can be used; Polyolefins such as ethylene (PE) or polypropylene (PP), ethylene-propylene copolymers; polycycloolefins derived from monomers with aliphatic ring structures such as nor-alkene structures; nylon 6, nylon 66, partially aromatic polyolefins Polyamide (PA) such as amide; polyimide (PI) such as transparent polyimide (CPI), polyamide imide (PAI); polyetheretherketone (PEEK); polyether (PES) ); polyphenylene sulfide (PPS); polycarbonate (PC); polyurethane (PU); ethylene-vinyl acetate copolymer (EVA); polyvinyl alcohol (PVA); polystyrene; ABS Resins; polyvinyl chloride; polyvinylidene chloride; fluorine resins such as polytetrafluoroethylene (PTFE); acrylic resins such as polymethyl methacrylate; cellulose such as diacetyl cellulose or triacetyl cellulose (TAC) polymers; vinyl butyral polymers; aryl ester polymers; polyoxymethylene polymers; epoxy polymers and other resins. The substrate layer disclosed herein may have its surface made of the above-mentioned resin materials. The resin film that can be used as the base material layer can be used by selecting an appropriate material from those formed using a resin material containing one of the above-mentioned resins alone, or those formed using a mixture of two or more resin materials. The above-mentioned resin film may also be a composite resin in which a resin layer containing one or more resin materials and a resin layer containing one or more resin materials of the same type or different types as the resin layer are laminated. membrane. The aforementioned resin film may be unstretched or stretched (for example, uniaxially stretched or biaxially stretched).

In some preferred aspects, a polyolefin resin film is used as the substrate layer. By using a polyolefin resin film, it is possible to preferably obtain a surface protection sheet exhibiting preferable characteristics with an appropriate thickness. Here, the term "polyolefin resin" refers to a resin containing polyolefin in a ratio exceeding 50% by weight. As the polyolefin resin, one type of polyolefin may be used alone or two or more types of polyolefins may be used in combination. The polyolefin may be, for example, a homopolymer of α-olefin, a copolymer of two or more α-olefins, a copolymer of one or more α-olefins and other vinyl monomers, and the like. Specific examples include ethylene-propylene copolymers such as PE, PP, poly-1-butene, poly-4-methyl-1-pentene, ethylene-propylene rubber (EPR), ethylene-propylene-butene Copolymer, ethylene-butene copolymer, ethylene-vinyl alcohol copolymer, ethylene-ethyl acrylate copolymer, etc. Both low density (LD) polyolefins and high density (HD) polyolefins can be used. Examples of polyolefin resin films include unstretched polypropylene (CPP) films, biaxially stretched polypropylene (OPP) films, low-density polyethylene (LDPE) films, linear low-density polyethylene ( LLDPE) film, medium density polyethylene (MDPE) film, high density polyethylene (HDPE) film, polyethylene (PE) film blended with two or more types of polyethylene (PE), blended with polypropylene (PP) PP/PE blended film with polyethylene (PE), etc. Among them, an OPP film is preferable from the viewpoint of moisture permeability.

Other preferable examples of the resin material constituting the resin film include fluororesins such as polyvinylidene chloride resin, PPS resin, polyurethane resin, EVA resin, and PTFE. Here, the polyvinylidene chloride resin refers to a resin containing polyvinylidene chloride in a ratio of more than 50% by weight. Similarly, a PPS resin refers to a resin containing PPS in a ratio exceeding 50% by weight. The same applies to polyurethane resin, EVA resin, and fluororesin. The polyolefin resins (PE, PP), or polyvinylidene chloride resins, PPS resins, polyurethane resins, EVA resins, and fluororesins listed above can be used in combination with other materials, or can be used alone And used as a substrate layer.

In the resin film, known additives such as light stabilizers, antioxidants, antistatic agents, colorants (dyes, pigments, etc.), fillers, lubricants, and antiblocking agents may be blended as needed. The compounding quantity of an additive is not specifically limited, According to a use etc., it can set suitably.

The manufacturing method of a resin film is not specifically limited. For example, conventionally known general resin film forming methods such as extrusion molding, inflation molding, T-die casting, and calender roll molding can be suitably used.

The said base material layer may consist essentially of such a resin film. Alternatively, the base material layer may also include an auxiliary layer in addition to the resin film. Examples of the above-mentioned auxiliary layer include: an optical characteristic adjustment layer (such as a coloring layer, an antireflection layer), a printing layer or a laminated layer for imparting a desired appearance, an antistatic layer, a primer layer, and a peeling layer. and other surface treatment layers.

In some other aspects, the base material layer has a layer containing an inorganic material (a layer containing an inorganic material). The effects brought about by the techniques disclosed herein can also be achieved by using a substrate layer including a layer containing an inorganic material. By arranging a layer containing an inorganic material, the barrier property (moisture permeability prevention) tends to be improved. In some aspects, as the substrate layer having a layer containing an inorganic material, for example, the above-mentioned resin film or the like is included as the substrate main layer, and the inorganic material is provided on at least one surface of the substrate main layer. The composition of the layers. In some other aspects, the substrate layer may also substantially include a layer containing an inorganic material.

As the inorganic material used in the above-mentioned inorganic material-containing layer, various metal materials including simple substances of transition metal elements or semi-metal elements, alloys, or inorganic compounds such as inorganic oxides that can form a hydrophilic surface can be used. The above-mentioned inorganic materials may be used alone or in combination of two or more. Preferable examples of inorganic materials include: titanium oxide, zinc oxide, magnesium oxide, aluminum oxide, silicon oxide, cerium oxide, chromium oxide, zirconium oxide, manganese oxide, zinc oxide, iron oxide, tin oxide, niobium oxide and other oxides (inorganic oxides, typically metal oxides). Among them, inorganic oxides such as silicon oxide can be used as a preferable inorganic material. Moreover, metal foil (metal material) such as aluminum foil, copper foil, and stainless steel (SUS) is mentioned as another preferable example of an inorganic material. In addition to the above-mentioned inorganic materials, the layer containing an inorganic material may or may not contain various organic materials including organic polymer compounds that can be used as coating agents or adhesives.

The amount of the inorganic material (for example, inorganic oxide such as silicon oxide) in the layer containing the inorganic material can be set to an appropriate amount to obtain the target hydrophilic surface, and is not limited to a specific range. For example, the content ratio of the inorganic material in the inorganic material-containing layer may be about 30% by weight or more, suitably about 50% by weight or more (for example, more than 50% by weight), or about 70% by weight or more. In some preferred aspects, the content ratio of the inorganic material in the layer containing the inorganic material is about 90 to 100% by weight (for example, about 95% by weight or more).

The method for forming the above-mentioned inorganic material-containing layer is not particularly limited, and can be formed by an appropriate method according to the intended thickness or the like. For example, an inorganic material formed into a layer by a known film-forming method such as a vacuum evaporation method, a sputtering method, or a plating method can be used. In the case of using an inorganic compound as an inorganic material, various evaporation methods can be used, such as physical evaporation (PVD) such as vacuum evaporation, sputtering, and ion plating, or chemical deposition such as atomic layer deposition. Evaporation method (CVD), etc. Formation of the coating layer containing an inorganic polymer such as polysiloxane can be appropriately selected from known coating agents that can obtain a surface exhibiting a desired water contact angle, and can be performed by conventional use.

The thickness of the layer containing the inorganic material is not particularly limited. In an aspect in which the substrate layer has a substrate main layer and an inorganic material-containing layer, the thickness of the inorganic material-containing layer is specifically determined from the viewpoint of not impairing the function of the substrate layer body (main layer of the substrate layer). It is suitably about 5 μm or less (for example, less than 5000 nm), and may be about 2 μm or less (for example, less than 2000 nm). In some aspects, the thickness of the layer containing the inorganic material is less than 1000 nm, more preferably less than 500 nm, further preferably less than 100 nm, especially less than 50 nm, and may be about 30 nm It may be less than about 20 nm, or less than about 15 nm (for example, less than 10 nm). By using such a thin inorganic material-containing layer, it is possible to impart desired properties such as barrier properties (moisture permeability prevention) to the base layer without impairing the function of the base layer (the main layer of the base layer) . It is also advantageous to use a thinner inorganic material-containing layer from the viewpoint of light weight and optical properties. In addition, the thickness of the layer containing the inorganic material is suitably 1 nm or more (for example, 3 nm or more), for example, from the viewpoint of reducing moisture permeability, it may be about 5 nm or more, or about 10 nm or more (for example, 15 nm or more). ).

In the aspect in which the above-mentioned base material layer has the base material main layer and the layer containing the inorganic material, the thickness of the base material main layer (in the case of having a plurality of layers other than the layer containing the inorganic material, is the layer containing the inorganic material The total thickness of other layers) is suitably at least 50% of the total thickness of the substrate layer, preferably at least 70%, more preferably at least 90%, and may be at least 97% (for example, at least 99%).

The base layer may have a single-layer structure, or may have a multi-layer structure of two or more layers. As a base material layer of a single-layer structure, the base material layer which consists of a resin film is mentioned. The substrate layer made of resin film is suitable for surface protection sheet for chemical solution treatment such as etching solution. It also tends to be excellent in softness or flexibility. As the base material layer of the multilayer structure, a configuration including a resin film of a multilayer structure, and a configuration having a base material main layer and a layer containing an inorganic material may, for example, be mentioned.

In some aspects, the base layer (the base film used as the base layer) preferably has a moisture permeability measured by the cup method of 24 g/(m ² ·day) or less. By adopting a structure having such a limited moisture permeability, even when used in a situation where it is in contact with aqueous liquids such as chemical solution treatment or warm water immersion, the presence of a low moisture permeability base layer can moderately prevent aqueous liquids from Penetration into the adhesive layer does not exhibit or suppresses the decrease in adhesive force due to water releasability. As a result, the adhesive force with respect to an adherend is maintained, and the surface protection sheet can maintain the adhesive state with an adherend. In some preferred aspects, the above-mentioned moisture permeability of the substrate layer is about 18 g/(m ² ·day), more preferably about 14 g/(m ² ·day), and more preferably about 10 g /( ^m2・day) or less, preferably less than about 8 g/( ^m2・day), or less than about 5 g/( ^m2・day) (for example, about 3 g/( ^m2・day) the following). Moreover, when the surface protection sheet is exposed to heat such as warm water, if the above-mentioned moisture permeability is too low, water releasability may not be effectively expressed due to aging due to heat. From this point of view, in some aspects, the moisture permeability of the substrate layer is suitably 1 g/(m ² ·day) or more, preferably about 3 g/(m ² ·day) or more, for example, may be More than 5 g/(m ² ·day).

More specifically, the above-mentioned moisture permeability of the substrate layer may be, for example, 23 g/(m ² ·day) or less, 22 g/(m ² ·day) or less, 21 g/(m ² ·day) Above or below, 20 g/(m ²・day) above or below, 19 g/(m ²・day) above or below, 18 g/(m ²・day) above or below, 17 g/(m ^2・day) day) above or below, 16 g/(m ² ·day) above or below, 15 g/(m ² ·day) above or below, 14 g/(m ² ·day) above or below, 13 g/(m ²・day) above or below, 12 g/( ^m2・day) above or below, 11 g/( ^m2・day) above or below, 10 g/(m2・day) above or below, 9 g/( ^m2・day) above or below (m ²・day) above or below, 8 g/(m ²・day) above or below, 7 g/(m ²・day) above or below, 6 g/(m ²・day) above or below, 5 g/(m ²・day) or more, 4 g/(m ²・day) or less, 3 g/(m ²・day) or more, 2 g/(m ²・day) or less , or above or below 1 g/(m ² ·day).

The aforementioned moisture permeability of the substrate layer can be obtained by selecting and using an appropriate substrate material with impermeable moisture permeability or low moisture permeability. More specifically, the water vapor transmission rate of the base material layer can be measured by the method described in the Examples described later.

The 25°C bending stiffness value of the substrate layer (substrate film used as the substrate layer) is in the same range as the range of the 25°C bending stiffness value obtained for the above-mentioned surface protection sheet, so repeated descriptions are omitted. Similarly, the ranges of the tensile modulus of elasticity at 25°C, the stress at 100% elongation at 25°C, the stress at break at 25°C, and the strain at break at 25°C for the substrate layer are also related to the tensile elasticity at 25°C of the surface protection sheet. The ranges of modulus, stress at 100% elongation at 25°C, breaking stress at 25°C and breaking strain at 25°C are the same, so repeated explanations are omitted. Regarding the bending stiffness at 25°C, tensile modulus at 25°C, stress at 100% elongation at 25°C, breaking stress at 25°C, and breaking strain at 25°C for the base layer, unless the base layer is used material film) as the test piece, can use the same as the 25 ℃ bending stiffness value, 25 ℃ tensile elastic modulus, 25 ℃ 100% elongation stress, 25 ℃ breaking stress and 25 ℃ breaking strain of the surface protection sheet respectively. method to measure. The thickness and cross-sectional area of the base material layer can be used as the thickness and cross-sectional area of the test piece for calculating the bending stiffness at 25°C, the tensile modulus of elasticity at 25°C, the stress at 100% elongation at 25°C, and the breaking stress at 25°C. Furthermore, the bending stiffness value at 25°C of the substrate layer is the same as the bending stiffness value at 25°C of the surface protection sheet. It is the 25°C bending stiffness value of at least one of the 25°C bending stiffness value of MD and the 25°C bending stiffness value of TD, or the 25°C bending stiffness value of any direction of MD or TD. Similarly, the 25°C tensile modulus of the substrate layer can be the 25°C tensile modulus of MD, or the 25°C tensile modulus of TD. Therefore, it can be the 25°C tensile modulus of MD. The 25°C tensile modulus of at least one of the modulus and the 25°C tensile modulus of TD, or the 25°C tensile modulus in either direction of MD or TD. Similarly, the stress at 100% elongation, breaking stress and breaking strain of the substrate layer can also be measured values of MD (stress at 100% elongation, breaking stress or breaking strain), and can also be measured values of TD. Therefore, It may be a measured value of at least one of a measured value of MD and a measured value of TD, or may be a measured value of either direction of MD or TD.

The thickness of the substrate layer is not particularly limited, and can be selected according to the purpose of protection or usage. The thickness of the substrate layer may be, for example, about 1000 μm or less, or about 300 μm or less. From the viewpoint of weight reduction or thinning, it is suitably about 200 μm or less, preferably about 150 μm or less, more preferably It may be about 100 μm or less, about 75 μm or less (typically, less than 75 μm), about 50 μm or less, 40 μm or less, or 30 μm or less. When the thickness of the base layer becomes smaller, the flexibility of the surface protection sheet or the followability to the surface shape of the adherend tends to improve. In addition, by limiting the thickness of the base layer, the deformation (expansion and contraction) of the base layer caused by heating is suppressed, so it is easy to maintain even when it is used in a heated state such as warm water immersion. Tendency to adhere to the adherend. In addition, the thickness of the base material layer may be, for example, 2 μm or more, or may exceed 5 μm from the viewpoint of handleability, processability, and the like. In some aspects, the thickness of the substrate layer is suitably more than about 10 μm, preferably more than about 15 μm, more preferably more than about 20 μm, or more than about 30 μm, or more than 40 μm, or It may be 50 μm or more. The larger the thickness of the base material layer, the easier it is to obtain a higher bending stiffness value, and the easier it is to improve the edge peeling resistance. In addition, there is a tendency to improve the protection of the adherend against the penetration of the drug solution and the like. In some other aspects, the thickness of the substrate layer may exceed 50 μm, may exceed 75 μm, or may exceed 90 μm.

The surface on the side of the adhesive layer of the substrate layer may be subjected to previously known surface treatments such as corona treatment or plasma treatment, ultraviolet irradiation treatment, acid treatment, alkali treatment, and primer coating, if necessary. Such surface treatment may be a treatment for improving the adhesion between the substrate layer and the adhesive layer, in other words, the gripping property of the adhesive layer on the substrate layer. The composition of the primer is not particularly limited, and can be appropriately selected from known ones. The thickness of the primer layer is not particularly limited, for example, it is suitably about 0.01 μm to 1 μm, preferably about 0.1 μm to 1 μm. In addition, the surface of the substrate main layer (typically, the surface on the side of the layer containing the inorganic material) may be subjected to various surface treatments such as the above-mentioned surface treatment and antistatic treatment.

The surface (hereinafter, also referred to as the back surface) of the substrate layer opposite to the adhesive layer side may be subjected to conventionally known surface treatments such as peeling treatment and antistatic treatment as needed. For example, the unwinding force of the surface protection sheet wound in the form of a roll can be reduced by surface-treating the back surface of a base material layer with a release treatment agent. As the peeling agent, silicone-based peeling agent, long-chain alkyl-based peeling agent, olefin-based peeling agent, fluorine-based peeling agent, fatty acid amide-based peeling agent, molybdenum sulfide, and silicon dioxide can be used. powder etc.

＜Total thickness＞ The thickness of the surface protection sheet disclosed herein (including the adhesive layer and the substrate layer, but excluding the release liner) is not particularly limited, and may be set to be 3 μm or more, may be 5 μm or more, and may be suitably 10 μm or more , from the viewpoint of adhesion to the adherend, such as step followability, is preferably 20 μm or more, more preferably 30 μm or more, further preferably 40 μm or more, and may be 45 μm or more. When the surface protection sheet has a thickness equal to or greater than a specific value, the edge peeling resistance tends to be improved as well. Also, the larger the thickness of the surface protection sheet, the more protective the adherend against the penetration of the chemical solution, etc., tends to be. In some aspects, the thickness of the surface protection sheet is greater than 50 μm, may be greater than 60 μm, may be greater than 70 μm, or may be greater than 80 μm. In some other aspects, the thickness of the surface protection sheet may exceed 50 μm, may exceed 75 μm, or may exceed 100 μm or more. The upper limit of the thickness of the surface protection sheet is, for example, 5 mm or less, may be 3 mm or less, or may be 1 mm or less. In some aspects, the thickness of the surface protection sheet is suitably less than 300 μm, preferably less than 200 μm, more preferably less than 150 μm, or less than 100 μm, or less than 75 μm, or less than 65 μm. μm or less, for example, may be 55 μm or less. By limiting the thickness of the surface protection sheet to a specific value or less, the surface protection sheet tends to suppress deformation (expansion and contraction) due to heating, and maintain an adhesive state to an adherend easily. Thinning the thickness of the adhesive sheet is also advantageous in terms of film reduction, miniaturization, weight reduction, resource saving, and the like.

＜Release liner＞ The release liner used for the surface protection sheet disclosed herein is not particularly limited. For example, a release liner whose surface has been released from a liner substrate such as a resin film or paper, or a release liner containing a fluorine-based polymer ( Polytetrafluoroethylene, etc.) or polyolefin-based resins (polyethylene, polypropylene, etc.) for release liners of low-adhesion materials, etc. In the above-mentioned peeling treatment, for example, a silicone-based, long-chain alkyl-based, or other peeling treatment agent can be used. In some aspects, it is preferable to use a release-treated resin film as a release liner.

＜Peel method＞ According to this specification, there is provided a peeling method of a surface protection sheet attached to an adherend (object to be protected). The above-mentioned peeling method includes a water peeling step, which is to make the above-mentioned aqueous The liquid follows the movement of the peeling front line and enters the interface to peel the surface protection sheet from the adherend. According to the said water peeling process, a surface protection sheet can be peeled from an adherend effectively using the said aqueous liquid.

As an aqueous liquid, it can be used in water or a mixed solvent with water as the main component, which may contain a small amount of additives if necessary. As a solvent other than water constituting the above-mentioned mixed solvent, a lower alcohol (such as ethanol) or a lower ketone (such as acetone) that can be uniformly mixed with water can be used. As said additive, a well-known surfactant etc. can be used. From the viewpoint of avoiding contamination of the adherend, in some aspects it may be preferable to use an aqueous liquid substantially free of additives. From the standpoint of sanitation, it is especially preferable to use water as the aqueous liquid. The water is not particularly limited, and it is possible to use, for example, distilled water, ion-exchanged water, tap water, etc., in consideration of the purity required by the application, ease of acquisition, and the like.

In some aspects, the above-mentioned peeling method can be preferably carried out in the following aspect, that is, the same as the measurement of the normal water peeling force FW0, on the vicinity of the outer edge of the surface protection sheet attached to the adherend After the aqueous liquid is supplied to the adherend so that the aqueous liquid enters the interface between the surface protection sheet and the adherend from the outer edge of the above-mentioned surface protection sheet, no new water is supplied (that is, only used for peeling off) Aqueous liquid supplied to the adherend before the start) to peel off the surface protection sheet. Furthermore, if the water that entered the interface between the surface protection sheet and the adherend following the movement of the peeling front line dries up in the middle of the water peeling step, it may be intermittently or intermittently after starting the water peeling step. Continuously add water. For example, when the adherend is water-absorbent, or when an aqueous liquid tends to remain on the adherend surface or adhesive surface after peeling, it is preferable to supply additional water after starting the water peeling step.

The amount of the aqueous liquid supplied before peeling is not particularly limited as long as the above-mentioned aqueous liquid can be introduced from outside the attachment range of the surface protection sheet to the interface between the surface protection sheet and the adherend . The amount of the above-mentioned aqueous liquid may be, for example, 5 μL or more, usually 10 μL or more, and may be 20 μL or more. Also, there is no particular limitation on the upper limit of the amount of the aforementioned aqueous liquid. In some aspects, the amount of the above-mentioned aqueous liquid may be, for example, 10 mL or less, or 5 mL or less, or 1 mL or less, or 0.5 mL or less, from the viewpoint of improving workability or the like. It may be less than 0.1 mL, or less than 0.05 mL. By reducing the amount of the above-mentioned aqueous liquid, the operation of removing the above-mentioned aqueous liquid by drying or wiping after peeling off the surface protection sheet can be omitted or simplified.

The operation of allowing the aqueous liquid to enter the interface between the surface protection sheet and the adherend from the outer edge of the surface protection sheet at the start of peeling can be performed, for example, in the following manner: Insert the tip of a cutter or needle into the interface, use a hook or nail to scratch the outer edge of the surface protection sheet and lift it up, and attach a strong adhesive tape or suction cup to the vicinity of the outer edge of the surface protection sheet Lift the end of the surface protection sheet, etc. from the back side. By forcibly entering the aqueous liquid from the outer edge of the surface protection sheet to the above-mentioned interface in this way, it is possible to efficiently form a state where the aqueous liquid exists at the interface between the adherend and the above-mentioned surface protection sheet. In addition, good water peelability after the operation of forcibly entering the aqueous liquid into the interface to form the starting point of peeling is performed, and high water resistance reliability when the operation is not performed.

＜Use＞ The surface protection sheet disclosed herein can be used as a surface protection sheet for various purposes. For example, in various treatments such as chemically treating glass, semiconductor wafers, metal plates, etc. with chemical solutions, or performing physical treatments such as cutting or grinding, the surface protection sheet disclosed herein can be attached to the above-mentioned protected object, for example. It is used for non-treatment surface.

The type of object to be protected is not particularly limited. The surface protection sheet disclosed herein can be used to protect various members or materials. The surface protection sheet disclosed herein can be peeled without damaging or deforming the adherend by peeling with water, and is therefore suitable for protecting glass materials such as alkali glass or semiconductor wafers. These materials are usually brittle materials (also known as hard and brittle materials) whose thickness is limited and are prone to cracks, defects, cracks, etc. due to external forces during operation or peeling. By applying peeling using water peeling to such an adherend, it is possible to preferably prevent the adherend from being damaged during peeling. The glass material that becomes the above-mentioned protected object can be, for example, a glass material with a partially provided transparent conductive film (such as ITO (indium tin oxide) film) or FPC used for tablet computers or mobile phones, organic LEDs (light-emitting diodes), etc. (Flexible Printed Circuit, flexible printed circuit board) surface glass plate. Moreover, as a preferable example of an object to protect, glass plates, such as a window glass and cover glass used for a foldable display or a rollable display, are mentioned. These glass plates are thinner (for example, less than 100 μm in thickness), and the risk of damage is greater. However, according to the technology disclosed in this paper, even when the protection object is a brittle material with a thinner thickness as described above , It can also prevent damage to the protected object when peeling off.

The water contact angle of the surface of the object to be protected to which the surface protection sheet is attached is not particularly limited. In some aspects, the surface of the object to be protected may be a surface showing hydrophilicity such that the water contact angle is, for example, 60 degrees or less, preferably 50 degrees or less. In some preferred aspects, the water contact angle of the above-mentioned surface may be, for example, less than 45 degrees, less than 40 degrees, less than 35 degrees, or less than 30 degrees. When the above-mentioned water contact angle becomes small, water tends to wet and diffuse along the surface of the adherend easily, and desired water releasability tends to be easily obtained. The surface protection sheet disclosed herein, for example, can be preferably used to protect materials (such as alkali glass plates or non-alkali glass, etc. ) surface components. In principle, the lower limit of the water contact angle on the surface of the object to be protected is 0°. In some aspects, the water contact angle on the surface of the object to be protected may be greater than 0 degrees, may be greater than 1 degree, may be greater than 3 degrees, or may be greater than 5 degrees. In some other aspects, the water contact angle on the surface of the object to be protected may exceed 30 degrees, may exceed 50 degrees, or may exceed 60 degrees (for example, 70 degrees or more). The surface protection sheet disclosed herein can be used for various materials with different water contact angles. The water contact angle on the surface of the object to be protected can be measured by the same method as the method for measuring the contact angle described in Examples described later.

The thickness of the object to be protected (such as a glass plate or a semiconductor wafer) is not particularly limited, and is, for example, less than about 1 mm, or less than about 500 μm or less than about 300 μm. As far as the effect (prevention of breakage during peeling) brought by the technology disclosed herein is more effectively exerted on a thinner object to be protected, the above-mentioned thickness may be, for example, about 150 μm or less, or about 100 μm the following. The lower limit of the aforementioned thickness is, for example, about 10 μm or more (for example, 30 μm or more).

In some preferred aspects, for example, it is suitable as a surface protection sheet used in the process of chemically and/or physically treating objects to be protected such as glass or semiconductor wafers in a liquid. The surface protection sheet disclosed herein can have the adhesiveness required for protecting the object to be protected during the above-mentioned treatment, and can be peeled off from the object to be protected (to be protected) by using water when peeling off after the treatment. Adhesives) were peeled off smoothly. The above-mentioned chemical treatment includes treatment with a chemical solution containing an acid or an alkali, such as an etching solution such as an aqueous hydrofluoric acid solution. For example, in order to adjust the thickness of the glass or remove the burrs or microcracks formed on the cutting end of the glass, the etching treatment of dissolving the glass with a chemical solution (etching solution), anti-glare processing, and the use of a chemical solution (etching solution) to make metal In the etching treatment of local corrosion of the surface, the plating treatment of local plating of the connecting terminal part of the circuit board (printed circuit board, flexible printed circuit board (FPC), etc.) by using a chemical solution (plating solution), etc., can be preferably Use the surface protection sheet disclosed herein. Among them, it can be preferably applied to the application of etching treatment using an acidic chemical solution such as a hydrofluoric acid solution. Also, physical processing includes grinding or cutting the surface of the object to be protected.

The surface protection sheet disclosed herein can be preferably used for glass thinning treatment. For example, a glass plate used as an optical member can be thinned by glass thinning treatment using a chemical solution such as hydrofluoric acid aqueous solution. In this glass thinning process, a surface protection sheet can be used to protect the non-treated surface of the glass. Although not particularly limited, in the glass thinning process, the glass plate is thinned to, for example, about 150 μm or less (for example, about 100 μm or less). Furthermore, the thickness of the glass plate before the glass thinning process is, for example, about 0.15 mm to 5 mm, and may be more than about 300 μm (for example, about 500 μm to 1000 μm). This kind of thinned glass is easy to break due to external force when peeling off, but by using the surface protection sheet disclosed herein, the problem of glass breakage when the surface protection sheet is peeled off can be eliminated, or the risk can be greatly reduced.

In addition, the surface protection sheet can also be preferably used in the manufacture of semiconductors. The above-mentioned semiconductor wafers can be compound semiconductor wafers such as silicon wafers, silicon carbide (SiC) wafers, nitride semiconductor wafers (silicon nitride (SiN), gallium nitride (GaN), etc.), gallium arsenide wafers, etc. circle etc. In the manufacture of the above-mentioned semiconductor, the surface protection sheet disclosed herein can be preferably used, for example, in the step of thinning the semiconductor wafer (more specifically, the back grinding step of grinding the back surface of the semiconductor wafer), Or a semiconductor wafer processing (typically, silicon wafer processing) step such as a step of cutting a semiconductor wafer (such as a dicing step). In the back grinding step, the semiconductor wafer is thinned to, for example, less than about 150 μm (eg, less than about 100 μm), but it is not particularly limited. Furthermore, the thickness of the semiconductor wafer before back grinding may be about 300 μm or more (for example, about 500 μm˜1000 μm). The above-mentioned semiconductor manufacturing steps may be exposed to temperatures higher than room temperature (for example, 40°C to 90°C, preferably 40°C to 60°C). Surface protection sheets are of particular interest. In addition, the surface protection sheet used for this application may be abbreviated as the sheet for back grinding, and the sheet for crystal cutting.

The surface protection sheet used in the above-mentioned various surface protection applications can be used in a state where one surface protection sheet is bonded to one side of one or more objects to be processed, and is conveyed, for example, by using a roller. A mechanism that transports a plurality of objects to be treated (also objects to be protected) continuously or individually into water such as a chemical solution tank or a washing tank to perform targeted treatment. During the above-mentioned transfer or post-transfer process (including placement or installation on a device, etc.), the object to be processed may be unavoidably or unintentionally subjected to external forces such as shock, vibration, and deformation. For example, a plurality of rollers arranged at specific intervals can be used as a transport mechanism used in chemical liquid treatment or cleaning treatment. Continuously apply a peeling load with a small peeling angle. The surface protection sheet disclosed herein has the following advantages: it is excellent in the prevention of edge peeling against external forces such as the above-mentioned vibrations, so as mentioned above, even if the object to be treated is in a state of being attached to the object to be treated, such as in a liquid When used in the process of medium processing steps, it is not easy to peel off from the end due to external forces such as vibration in the process. In addition, in the aspect of performing physical processing such as dicing or grinding on the object to be processed such as a semiconductor wafer, the external force in the physical processing will become a peeling load, but according to the surface protection sheet disclosed herein, even in physical processing When subjected to physical load during the process, it is not easy to peel off from the end. In addition, the vibration in the said conveyance process or the physical load (also called peeling load) in a physical processing process typically includes the load applied along the thickness direction of a surface protection sheet.

In addition, the above-mentioned protected object may be, for example, a member constituting the following equipment: a liquid crystal display device, an organic EL (electroluminescent) display device, a PDP (plasma display panel), an electronic paper or other display device (image display device), or Devices such as input devices such as touch panels (optical devices), especially portable electronic devices such as foldable displays and rollable displays.

Examples of the above-mentioned portable electronic devices include, for example: mobile phones, smart phones, tablet computers, notebook computers, various wearable devices (for example, wrist wear type worn on the wrist like a watch, clips, etc.) (clip) or strap (strap), etc., which are worn on a part of the body, including eyewear (single-eye or binocular, also including head-mounted) eyewear, such as accessories. Clothing type such as shirts, socks, hats, etc., earphones that are installed on the ear, etc.), digital cameras, digital video cameras, audio equipment (portable music players, IC recorders, etc.), computing devices (electronic desktop calculators, etc.), portable game consoles, electronic dictionaries, electronic notebooks, electronic books, information equipment for vehicles, portable radios, portable TVs, portable printers, portable scanners, portable modems, etc. Furthermore, in this specification, the so-called "carrying" does not mean merely being able to carry, but rather means having a level of portability that is relatively easy for an individual (standard adult) to carry.

＜Protection method＞ As described above, according to this specification, there is provided a surface protection method using the surface protection sheet disclosed herein. The surface protection method includes: a step of attaching a surface protection sheet to at least a part of the object to be protected (the surface of the object to be protected or a portion of the object to be protected); performing treatment (such as chemical solution treatment) on the object to be protected to which the surface protection sheet is attached. , warm water immersion treatment, water immersion treatment, physical treatment such as cutting or grinding), and a step of peeling the surface protection sheet from the object to be protected after the above treatment. Here, the step of peeling the surface protection sheet from the object to be protected preferably includes the above-mentioned water peeling step. The above protection method is also referred to as a treatment method because it includes treatment of the object to be protected (object to be processed). Details of the surface protection sheet, the water stripping process, the object to be protected, the treatment (glass thinning treatment, semiconductor wafer thinning treatment, etc.), and other items (applications, etc.) are as described above, so repeated descriptions are omitted. Typical examples of objects to be protected include glass plates, semiconductor wafers, and the like that are subjected to processes such as glass thinning. Therefore, according to the present specification, a glass thinning method and a semiconductor manufacturing method including the above-mentioned steps can be provided.

<Treatment method> Moreover, as mentioned above, according to this specification, the processing method using the surface protection sheet disclosed here is provided. The treatment method includes: a step of attaching a surface protection sheet to the surface of the adherend; a step of applying a physical load to the adherend with the surface protection sheet attached along the thickness direction of the surface protection sheet; The step of removing the protective sheet from the adherend. The surface of the above-mentioned adherend to which the surface protection sheet is attached is typically a surface with a water contact angle of 20 degrees or less. Also, the step of removing the surface protection sheet from the adherend is preferably a step of peeling and removing the surface protection sheet from the adherend in the presence of water. Moreover, typically, the said processing method may include the process of processing the adherend (object to be processed) to which the surface protection sheet was attached. In this treatment step, the object to be treated may be brought into contact with a liquid (for example, an aqueous solution). In addition, the treatment method disclosed herein may include at least one step of the protection method described above. As the surface protection sheet, the surface protection sheet disclosed herein can be used. In some aspects, it is possible to use a surface protection that satisfies that the bending stiffness value at 25°C is in the range of 1.0×10 ^-6 to 1.0×10 ^-2 Pa·m ³ and the water peeling force FW0 is 1.0 N/20 mm or less Sheet. In other several aspects, the surface protection sheet which satisfies the water peeling force FW0 of 1.0 N/20 mm or less and the starting point peeling force of 0.5 N/10 mm or more can be used. Examples of processing include glass thinning and semiconductor processing, and typical examples of processed objects include glass plates and semiconductor wafers to be subjected to glass thinning and the like. In addition, as a typical example of the step of applying a physical load to the adherend with the surface protection sheet attached in the thickness direction of the surface protection sheet, a step of conveying the adherend or a step of physically treating the adherend can be mentioned. . As described above, according to the present specification, there can be provided a glass thinning method and a semiconductor manufacturing method including the above steps. Details of surface protection sheet, water peeling, removal procedure, adherend (object to be treated), treatment (glass thinning treatment, semiconductor wafer thinning treatment, etc.), other matters (usage, etc.) are as described above, so they are omitted Description of repetition. [Example]

Hereinafter, some examples related to the present invention will be described, but the present invention is not intended to be limited to those shown in these examples. In addition, in the following description, unless otherwise indicated, "part" and "%" are based on weight.

＜Evaluation method＞ [Normal adhesion F0] The surface protection sheet to be measured was cut into a size of 20 mm in width and 100 mm in length to prepare a test piece. In an environment of 23°C and 50% RH, the release liner covering the adhesive surface (adhesive layer surface) was peeled off from the above test piece, and a 2 kg rubber roller was reciprocated once to press-bond the exposed adhesive surface to the test piece as Alkali glass plate of the adherend (the surface of the alkali glass having a surface with a water contact angle of 20 degrees or less). The sample for evaluation thus obtained was subjected to autoclave treatment (50° C., 0.5 MPa, 15 minutes). After keeping the evaluation sample taken out from the autoclave at 23°C and 50%RH for 1 hour, in the same environment, according to JIS Z0237: 2009 10.4.1 Method 1: 180° peel adhesion to the test board , using a tensile testing machine, measure the peel strength of the test piece from the adherend under the conditions of a tensile speed of 300 mm/min and a peeling angle of 180 degrees (wherein, before the transition to the following water peeling force measurement, that is, for peeling Peel strength before the interface is supplied with distilled water). The measurement was carried out 3 times, and the average value thereof was set as the normal adhesive force F0 [N/20 mm]. The above-mentioned normal state adhesive force F0 is measured by peeling off the test piece attached to the adherend from bottom to top. As an adherend, an alkali glass plate (product name "Micro Slide Glass (Micro Slide Glass) S200423", manufactured by Matsunami Glass Industry Co., Ltd.) can be used. As a tensile tester, a universal tensile-compression tester (device name "tensile-compression tester, TCM-1kNB", manufactured by Minebea Corporation) or an equivalent thereof can be used. During the measurement, the test piece can also be reinforced by attaching an appropriate substrate material on the opposite side of the surface protection sheet (the surface opposite to the adhesive side) as needed. As a substrate material, for example, a polyethylene terephthalate (PET) film having a thickness of about 25 μm can be used.

[Normal water peeling force FW0] In the measurement of the above-mentioned normal state adhesive force F0, in the measurement of the peel strength of the test piece from the adherend, 20 μL of distilled water was supplied to the part where the test piece started to separate from the above-mentioned adherend (peeling front line), and the distilled water was measured. Peel strength after supply. The measurement is carried out at each measurement of the normal adhesive force F0 (that is, 3 times), and the average value thereof is set as the normal water peeling force FW0 [N/20 mm]. The measurement conditions of the peel strength after distilled water supply are based on JIS Z0237:2009 10.4.1 method 1: 180° peel adhesion to the test board. Specifically, a tensile testing machine was used at a test temperature of 23° C. under the conditions of a tensile velocity of 300 mm/min and a peeling angle of 180°. Furthermore, the determination of the normal water peeling force FW0 can be carried out continuously on each test piece for the determination of the normal adhesive force F0 and the normal water peeling force FW0, and the normal adhesive force F0 can also be measured and Determination of normal water peeling force FW0. For example, when it is difficult to prepare test pieces of sufficient length for continuous measurement, it is possible to use different test pieces for measurement. Regarding the adherend, tensile testing machine, and other matters, it is the same as the measurement of the normal adhesion force F0.

[Adhesion F1 after immersion in warm water for 30 minutes] After 30 minutes of warm water immersion, adhesion force F1 is to immerse the sample for evaluation (alkali glass plate with a test piece (surface protection sheet) attached) in warm water at 60°C±2°C for 30 minutes, and then lift it out of the warm water And after wiping off the attached water, the peel strength was measured. Except for this, it was measured by the same method as the normal adhesive force F0. Specifically, similarly to the measurement of the normal adhesive force F0, the surface protection sheet to be measured was cut into a size of 20 mm in width and 100 mm in length to prepare a test piece. In an environment of 23°C and 50% RH, the release liner covering the adhesive surface (adhesive layer surface) was peeled off from the above test piece, and a 2 kg rubber roller was reciprocated once to press-bond the exposed adhesive surface to the test piece as The alkali glass plate of the adherend. The sample for evaluation thus obtained was subjected to autoclave treatment (50° C., 0.5 MPa, 15 minutes). The evaluation sample taken out from the autoclave was immersed in a water bath filled with warm water at a set temperature of 60°C±2°C for 30 minutes. As warm water, ion-exchanged water or distilled water is used. In warm water, the sample for evaluation was kept horizontally with the adhesive layer facing upward. The distance (immersion depth) from the upper surface of the sample for evaluation to the water surface is set to 10 mm or more (for example, about 10 mm to 100 mm). Next, lift the sample for evaluation from warm water, wipe off the water adhering to the sample for evaluation lightly, and then, in an environment of 23°C and 50%RH, follow JIS Z0237:2009 10.4.1 Method 1: For For the 180° peel adhesion of the test plate, use a tensile testing machine to measure the peel strength of the test piece from the adherend under the conditions of a tensile speed of 300 mm/min and a peel angle of 180 degrees (wherein, regarding the transition to the following water Peel strength before measurement of peel force, that is, before distilled water is supplied to the peel interface). The measurement was carried out 3 times, and the average value was set as the adhesion force F1 [N/20 mm] after immersion in warm water for 30 minutes. The time from pulling up the sample for evaluation from warm water to measuring the peel strength was within 10 minutes. Regarding the adherend, tensile testing machine, and other matters, it is the same as the measurement of the normal adhesion force F0.

[Water peeling force FW1 after immersion in warm water for 30 minutes] Water peeling force FW1 after 30 minutes of warm water immersion is to immerse the sample for evaluation (alkali glass plate with a test piece (surface protection sheet) attached) in warm water at 60°C±2°C for 30 minutes, and then remove it from the warm water After pulling up and wiping off the attached water, the water peeling force was measured, and measured by the same method as the normal water peeling force FW0 except that. Specifically, in the measurement of the adhesive force F1 after 30 minutes of warm water immersion, after 30 minutes of warm water immersion, in the measurement of the peel strength of the test piece from the adherend, the test piece from the above adherend 20 μL of distilled water was supplied to the site where the separation started (peeling front), and the peel strength after the supply of the distilled water was measured. The measurement is carried out at each measurement of the adhesion force F1 after 30 minutes of warm water immersion (ie 3 times), and the average value thereof is set as the water peeling force FW1 after 30 minutes of warm water immersion [N/20 mm]. The measurement conditions of the peel strength after distilled water supply are based on JIS Z0237:2009 10.4.1 method 1: 180° peel adhesion to the test board. Specifically, a tensile testing machine was used at a test temperature of 23° C. under the conditions of a tensile velocity of 300 mm/min and a peeling angle of 180°. Furthermore, the determination of the water peeling force FW1 after 30 minutes of warm water immersion can be carried out continuously for each piece of test piece after 30 minutes of warm water immersion adhesive force F1 measurement and 30 minutes of warm water immersion after the determination of the water peeling force FW1, also Different test pieces can be used to measure the adhesion force F1 after 30 minutes of warm water immersion and the measurement of the water peeling force FW1 after 30 minutes of warm water immersion. Regarding the adherend, tensile testing machine, and other matters, it is the same as the measurement of the normal adhesion force F0.

In the above measurement (measurement of F0, FW0, F1 and FW1), as the adherend, the contact angle of the surface of the bonded test piece to distilled water is 20 degrees or less (for example, 5 degrees to 10 degrees). Specifically, as the adherend, an alkali glass plate can be used. The alkali glass plate is made by the float method, and the contact angle of the surface of the test piece to the distilled water is 20 degrees or less (for example, 5 degrees to 10 degrees). Spend). As such an adherend, the above-mentioned soda glass plate manufactured by Matsunami Glass Co., Ltd. can be used, but it is not limited to this, and an equivalent product of the soda glass plate produced by Matsunami Glass Co., Ltd., or other soda glass plate can also be used. .

Moreover, the contact angle of the said alkali glass plate was measured by the following method. That is, under the environment of the measurement atmosphere of 23°C and 50%RH, a contact angle meter (manufactured by Kyowa Interface Science Co., Ltd., trade name "DMo-501 type"), a control box "DMC-2", and a control/analysis software "FAMAS ( Version 5.0.30)") was determined by the droplet method. The amount of distilled water added was set at 2 μL, and the contact angle was calculated by the Θ/2 method (implemented with N5) based on the image after 5 seconds of dropping.

Furthermore, the inventors of the present invention have confirmed that the adhesive force and water peeling force after immersion in warm water and the adhesive force and water peeling force after immersion in aqueous hydrofluoric acid solution respectively show a constant high correlation. Based on this finding, the above-mentioned adhesive force after warm water immersion and water peeling force were used as evaluation indexes of the applicability of the surface protection sheet in the use of submerged treatment including chemical solution immersion.

[60°C Loss Modulus of Elasticity G"] The 60°C loss elastic modulus G"[Pa] of the adhesive layer was obtained by dynamic viscoelasticity measurement. Specifically, a plurality of sheets of the adhesive layer to be measured were stacked to produce a thickness of about 2 mm. Adhesive layer. The adhesive layer is punched into a disc shape with a diameter of 7.9 mm to obtain a sample, and the obtained sample is clamped and fixed by a parallel plate. , ARES or its equivalent) under the following conditions to perform dynamic viscoelasticity measurement, and obtain the loss elastic modulus G"[Pa] at 60°C. ・Measurement mode: Cutting mode ・Temperature range: -70℃～150℃ ・Heating rate: 5°C/min ・Measurement frequency: 1 Hz Furthermore, the adhesive layer to be measured can be formed by applying a corresponding adhesive composition in a layered form and drying or hardening.

[Moisture Permeability] The moisture permeability of the substrate (layer) and the surface protection sheet was measured in accordance with the moisture permeability test (cup method) of JIS Z0208. The moisture permeability measurement method of the base material is as follows. That is, the base material of each example was cut into a circle of 7 cmϕ, and this was used as a sample for evaluation. Then, a specific amount of calcium chloride was added to the inside of the test cup (made of aluminum, a moisture-permeable cup specified in JIS Z0208), and the mouth of the cup was sealed with the above-mentioned sample for evaluation. Specifically, the evaluation sample was placed on the test cup so as to cover the mouth of the test cup, and the edge (inner diameter 6 cm, external shape 9 cm, edge width 1.5 cm) Circle) A ring-shaped gasket and cover of the same shape are superimposed on it and fixed with a special screw plug, thereby sealing the inside of the test cup. Next, the cup covered with the evaluation sample was stored at 40°C and 92%RH for 24 hours, and the change in total weight before and after storage (specifically, the weight change based on the water absorption of calcium chloride) was measured to obtain Moisture permeability [g/(m ²・day)]. The water vapor transmission rate of the surface protection sheet is measured by placing the surface protection sheet in such a way that the cup side becomes the bonding surface instead of the base material, and sealing the mouth of the cup. method to measure.

[Tension Test] The surface protection sheet was cut into strips with a width of 10 mm to prepare test pieces. According to JIS K 7161, the stress-strain curve was obtained by stretching this test piece under the following conditions. (Extension conditions) Measuring temperature: 25°C Tensile speed: 300 mm/min Distance between chucks: 50 mm As a tensile testing machine, a universal tensile and compression testing machine (device name "tensile compression testing machine, TCM- 1kNB", manufactured by Minebea) or its equivalent. The tensile elastic modulus [Pa] at 25°C was obtained from the linear regression of the above stress-strain curve. Furthermore, the tensile modulus of elasticity at 25°C is based on the value obtained by subtracting the thickness of the adhesive layer from the actually measured value of the thickness of the surface protection sheet, or the value obtained by measuring the thickness of the substrate layer itself. Calculate the value of the cross-sectional area per unit of the material layer. Also, the stress at 100% elongation [N/mm ² ], breaking stress [N/mm ² ] and breaking strain [%] at 25°C were measured according to the above-mentioned tensile test. The above-mentioned stress at 100% elongation is the value obtained by dividing the load [N] measured at 100% elongation of the test piece in the above tensile test by the cross-sectional area [mm ² ] of the substrate layer of the test piece. The above breaking stress is the value obtained by dividing the load [N] of the test piece in the tensile test above by the cross-sectional area of the base material layer of the test piece [mm ² ]. The above breaking strain [%] is the fracture of the above test piece Time elongation [%]. Furthermore, the measured values (tensile elastic modulus, stress at 100% elongation, breaking stress, and breaking strain) in this example were obtained by comparing the MD of the surface protection sheet (more specifically, the substrate layer) with the above-mentioned tensile strength. The tensile direction of the tensile test is the same as the measured value of MD, but the above tensile test can not only be carried out on the MD of the surface protection sheet, but also by changing the cutting method of the test piece, the TD of the surface protection sheet The measurement value of TD was obtained by carrying out the above-mentioned tensile test. Alternatively, the above-mentioned tensile test may be performed in either direction of MD or TD to obtain a measured value.

[Bending stiffness value at 25°C] The bending stiffness value D [Pa·m ³ ] of the surface protection sheet at 25°C is calculated according to the formula: D=Eh ³ /12(1-ν ² ); In the above formula, E is the 25°C tensile elastic modulus [Pa] of the surface protection sheet, and h is the thickness of the substrate layer [m]. ν is Poisson's ratio, and it is set as ν=0.35 in the above formula. Furthermore, the 25°C bending stiffness value in this example is the 25°C bending stiffness value of MD, but by changing the cutting method of the test piece as mentioned above, not only the 25°C bending stiffness value of MD, but also the TD value can be obtained. The 25°C bending stiffness value, or the 25°C bending stiffness value in any direction of MD or TD can also be obtained.

[Peel force at starting point in water] The surface protection sheet to be measured was cut into a size of 10 mm in width and 100 mm in length to prepare a test piece. In an environment of 23°C and 50% RH, the release liner covering the adhesive surface (adhesive layer surface) was peeled off from the above test piece, and a 2 kg rubber roller was reciprocated once to press-bond the exposed adhesive surface to the test piece as Alkali glass plate of the adherend (the surface of the alkali glass having a surface with a water contact angle of 20 degrees or less). At this time, the test piece is bonded so that one end of the test piece in the longitudinal direction protrudes from the adherend. The sample for evaluation thus obtained was subjected to autoclave treatment (50° C., 0.5 MPa, 15 minutes). The evaluation sample taken out from the autoclave was kept in an environment of 23° C. and 50% RH for 1 hour, and then immersed in water at room temperature (23° C. to 25° C.). As water, ion-exchanged water or distilled water is used. In water, the sample for evaluation is maintained horizontally with the side to which the test piece is attached facing upward. The distance (immersion depth) from the upper surface of the sample for evaluation to the water surface is set to 10 mm or more (for example, about 10 mm to 100 mm). In this way, with the sample for evaluation placed in water, within 1 minute from the start of immersion in the water, in an environment of 23°C and 50% RH, use a tensile tester from one end of the test piece in the longitudinal direction (from The protruding end of the adherend), the peeling test was carried out under the conditions of a tensile speed of 1000 mm/min and a peeling angle of 20 degrees, and the maximum stress applied at the initial stage of peeling was recorded. The measurement was carried out three times, and the average value of the above-mentioned maximum stress was defined as the starting point peeling force in water [N/10 mm]. When the starting point peeling force in water is 0.2 N/10 mm or more, it is judged that the edge peeling prevention property against external force such as vibration during the conveying process is excellent. The external force such as vibration that may cause the edge peeling of the surface protection sheet during the process of conveyance can be considered as a high-speed peeling load applied to the object to be protected at a relatively small angle. It can be judged that the surface protection sheet with a peeling force of 0.2 N/10 mm or more under the conditions of a peeling angle of 20 degrees and a peeling speed of 1000 mm/min has a large stress before being peeled off by the above peeling load. Excellent resistance to end peeling against external forces such as vibration. In the above test, an alkali glass plate (product name "Micro Slide Glass (Micro Slide Glass) S200423", manufactured by Matsunami Glass Co., Ltd.) was used as an adherend. As a tensile tester, a universal tensile-compression tester (device name "tensile-compression tester, TCM-1kNB", manufactured by Minebea Corporation) or an equivalent thereof can be used. During the measurement, the test piece can also be reinforced by attaching an appropriate substrate material on the opposite side of the surface protection sheet (the surface opposite to the adhesive side) as needed. As a substrate, for example, a PET film with a thickness of about 25 μm can be used.

[Peel force at 20 degrees starting point] The surface protection sheet to be measured was cut into a size of 10 mm in width and 100 mm in length to prepare a test piece. In an environment of 23°C and 50% RH, the release liner covering the adhesive surface (adhesive layer surface) was peeled off from the above test piece, and a 2 kg rubber roller was reciprocated once to press-bond the exposed adhesive surface to the test piece as Alkali glass plate of the adherend (the surface of the alkali glass having a surface with a water contact angle of 20 degrees or less). At this time, the test piece is bonded so that one end of the test piece in the longitudinal direction protrudes from the adherend. After keeping the sample for evaluation thus obtained in an environment of 23°C and 50% RH for 24 hours, between the adhesive surface of the test piece protruding from the above-mentioned adherend and the above-mentioned adherend (the end of the above-mentioned adherend) Part) Add 20 μL of distilled water dropwise, and use a tensile testing machine at 23°C and 50% RH, from one end of the above-mentioned test piece in the longitudinal direction (the end protruding from the adherend) at a temperature of 23°C , The peeling test was carried out under the conditions of a peeling angle of 20 degrees and a tensile speed of 1000 mm/min, and the maximum stress applied at the initial stage of peeling was recorded. The measurement was carried out three times, and the average value of the above-mentioned maximum stress was set as the 20-degree starting point peeling force [N/10 mm]. Furthermore, the above-mentioned 20-degree starting point peeling force is measured by dropping water on the peeling start site, and the influence of the presence or absence of water at the start of peeling is negligible. The reason is that, as mentioned above, the peeling force at the starting point is the maximum stress applied at the initial stage of peeling, and the water peeling property (reduced peeling force due to the presence of water) in the technology disclosed herein is after the peeling starts ( The characteristics shown after the starting point peeling force test), the water peeling force is the peeling strength measured after the peeling starts. According to the above-mentioned surface protection sheet whose peeling force at the starting point of 20 degrees is more than a specific value, regardless of the presence of water, the peeling from the end of the surface protection sheet is based on the physical load applied to the end of the surface protection sheet along the thickness direction of the surface protection sheet. The occurrence can be prevented or suppressed. In the above test, an alkali glass plate (product name "Micro Slide Glass (Micro Slide Glass) S200423", manufactured by Matsunami Glass Co., Ltd.) was used as an adherend. As a tensile tester, a universal tensile-compression tester (device name "tensile-compression tester, TCM-1kNB", manufactured by Minebea Corporation) or an equivalent thereof can be used. During the measurement, the test piece can also be reinforced by attaching an appropriate substrate material on the opposite side of the surface protection sheet (the surface opposite to the adhesive side) as needed. As a substrate, for example, a PET film with a thickness of about 25 μm can be used.

[repulsion resistance (aluminum repulsion resistance)] The adhesive layer protected by the release film was cut into a size with a width of 10 mm and a length of 110 mm. Use toluene to clean the surface of the aluminum plate with a width of 10 mm, a length of 110 mm, and a thickness of 0.03 mm, and peel off the release liner covering one of the bonding surfaces of the above-mentioned adhesive layer, so that the exposed bonding surface is attached to the surface of the above-mentioned aluminum plate , to make a measurement sample (a laminate of an aluminum plate and an adhesive layer) in which the adhesive layer is made of an aluminum plate as a substrate. After the measurement sample was left to stand at 23°C for 1 day, with the aluminum plate side of the measurement sample on the inside, bend the longitudinal direction of the measurement sample along the outer periphery of a cylindrical glass tube with a radius of 17 mm for 10 seconds. . Next, peel off the other release liner covering the adhesive layer of the sample for measurement, and press-bond it to the alkali glass as the adherend under the conditions of a bonding pressure of 0.25 MPa and a bonding speed of 0.3 m/min using a bonding machine. The surface of the plate was observed at 23°C and 50%RH. In Experiment 2 described later, the peeling distance (peeling length from one end) [mm] of the sample for measurement from the adherend after 1 hour after being crimped to the adherend was measured, and recorded as the evaluation result of rebound resistance. The rebound resistance test described above evaluates the difficulty of peeling the adhesive against a physical load (peeling load) at the end of the surface protection sheet in a direction perpendicular to the direction of the surface of the surface protection sheet (thickness direction of the surface protection sheet). A test of sex. In the above-mentioned rebound resistance test, an adhesive having no or less peeling at the end was evaluated as having excellent end-peeling resistance against a physical load applied in the above-mentioned thickness direction. Furthermore, the present inventors confirmed that the peeling length in the above-mentioned rebound resistance test is related to the above-mentioned 20-degree starting point peeling force. Specifically, in the rebound resistance test, it was confirmed that the shorter the end peeling length is, the higher the 20-degree starting point peeling force tends to be. The reason for this is considered to be that when peeling at a peeling angle of 20 degrees, the ratio of the component acting in the vertical direction (90 degrees) in the peeling stress of the adhesive is high. In addition, the reason why water was not applied in the rebound resistance test is to exclude the influence of swelling of the adhesive due to water, etc. in the time-dependent evaluation of the rebound resistance.

"Experiment 1" ＜Preparation of Adhesive＞ (Adhesive S1) Add 72 parts of 2-ethylhexyl acrylate (2EHA) and N-vinyl-2-pyrrolidone (NVP) 14 parts, 13 parts of 2-hydroxyethyl acrylate (HEA) and 1 part of methyl methacrylate (MMA), 0.12 parts of α-thioglycerol as a chain transfer agent, ethyl acetate as a polymerization solvent, input as a hot The AIBN of the polymerization initiator was 0.2 part, and solution polymerization was carried out under a nitrogen atmosphere to obtain a solution containing an acrylic polymer s1 with a Mw of 300,000.

In the solution obtained above, for every 100 parts of the monomer components used to prepare the solution, add an isocyanate-based crosslinking agent (trimethylolpropane/xylylene diisocyanate adduct, manufactured by Mitsui Chemicals, commercial product Name: Takenate D-110N, solid content concentration 75%) 0.75 parts based on solid content, dioctyltin dilaurate (manufactured by Tokyo Fine Chemical Co., trade name: EMBILIZER OL-1) as a crosslinking accelerator ) 0.01 part, 3 parts of acetylacetone as cross-linking retarder and nonionic surfactant (polyoxyethylene sorbitan monolaurate, HLB16.7, trade name: RHEODOL TW-L120 , manufactured by Kao Corporation) 0.3 parts were uniformly mixed to prepare solvent-based adhesive composition S1.

A release film with a thickness of 38 μm (manufactured by Mitsubishi Plastics Co., Ltd., MRF#38) with one side of the polyester film as the release surface and a release film with a thickness of 38 μm (manufactured by Mitsubishi Plastics Co., Ltd.) with one side of the polyester film as the release surface were prepared. , MRE #38). Coat the solvent-based adhesive composition S1 prepared above on the peeling surface of a release film (MRF#38), dry at 60°C for 3 minutes, and then dry at 120°C for 3 minutes to form an adhesive with a thickness of 25 μm layer. The release surface of another release film (MRE#38) was bonded to this adhesive layer for protection. In this way, the adhesive layer S1 whose surface is protected by two release films is obtained.

(Adhesive E1) 85 parts of 2EHA, 13 parts of methyl acrylate (MA), 1.2 parts of acrylic acid (AA), 0.75 parts of methacrylic acid (MAA), 3-glycidyloxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM- 0.01 part of 403), 0.05 part of tertiary-dodecylmercaptan as a chain transfer agent, and 1.9 parts of an emulsifier (manufactured by Kao Corporation, Latemul E-118B) were mixed and emulsified in 100 parts of ion-exchanged water, thereby An aqueous emulsion of the monomer mixture (monomer emulsion) is prepared. Add the above-mentioned monomer emulsion into a reaction vessel equipped with a cooling tube, a nitrogen gas introduction tube, a thermometer, and a stirring device, and stir at room temperature for more than 1 hour while introducing nitrogen gas. Then, the system was heated up to 60°C, and 2,2'-azobis[N-(2-carboxyethyl)-2-methylpropionamidine] hydrate (Wako Pure Chemical Industries, Ltd. Manufactured, 0.1 part of VA-057), reacted at 60°C for 6 hours to obtain an aqueous dispersion of acrylic polymer e1. After the system was cooled to normal temperature, for every 100 parts of the solid content of the aqueous dispersion of the acrylic polymer e1, 10 parts of an adhesion-imparting resin emulsion (manufactured by Arakawa Chemical Industry Co., Ltd., SUPER ESTER E- 865 NT, aqueous dispersion of polymerized rosin ester with a softening point of 160°C). Furthermore, the pH value was adjusted to about 7.5 and the viscosity was adjusted to about 9 Pa·s by using 10% ammonia water as a pH adjuster and polyacrylic acid (aqueous solution of 36% non-volatile matter) as a thickener. Emulsion adhesive composition E1.

A release film with a thickness of 38 μm (manufactured by Mitsubishi Plastics Co., Ltd., MRF#38) with one side of the polyester film as the release surface and a release film with a thickness of 38 μm (manufactured by Mitsubishi Plastics Co., Ltd.) with one side of the polyester film as the release surface were prepared. , MRE#38). The adhesive composition E1 was coated on the peeling surface of a release film (MRF#38), and dried at 120°C for 3 minutes to form an adhesive layer E1 with a thickness of 25 μm. The release surface of another release film (MRE#38) was bonded to this adhesive layer for protection. In this way, an adhesive layer E1 whose surface was protected by two release films was obtained. The 60°C loss elastic modulus G" of the adhesive layer E1 is 12.3 kPa.

<Example 1> As the material of the substrate layer, a stretched polypropylene (OPP) film with a thickness of 60 μm (product name "Torayfan #60-2500", manufactured by Toray Corporation, biaxially stretched PP film, moisture permeability 2.1 g/( m ²・day)). The release liner covering one surface of the adhesive layer S1 with release liner obtained above was peeled off, and a 2 kg rubber roller was reciprocated twice to press-bond the exposed surface (adhesive surface) to the above OPP film the surface. In this way, a surface protection sheet (one-sided adhesive sheet with a substrate layer) having the adhesive surface protected by a release liner is obtained. The bending stiffness of the surface protection sheet in this example is 1.2×10 ^-4 Pa·m ³ at 25°C, the tensile elastic modulus at 25°C is 5.8×10 ⁹ Pa, and the stress at 100% elongation at 25°C is 83 N/mm ^2. The breaking stress at 25°C is 131 N/mm ² , and the breaking strain at 25°C is 232%.

<Example 2> OPP film with a thickness of 25 μm (product name "Torayfan #25A-KW37", manufactured by Toray Co., Ltd., biaxially stretched PP film, moisture permeability 6.4 g/(m ² ·day) was used as the material of the base layer ). Furthermore, in the same manner as in Example 1, the surface protection sheet of this example was obtained. The bending stiffness of the surface protection sheet in this example at 25°C is 9.3×10 ^-6 Pa·m ³ , the tensile elastic modulus at 25°C is 6.3×10 ⁹ Pa, and the stress at 100% elongation at 25°C is 85 N/mm ^2. The breaking stress at 25°C is 146 N/mm ² , and the breaking strain at 25°C is 239%.

<Example 3> A PET film (product name "Lumirror S10", manufactured by Toray Corporation) with a thickness of 100 μm was used as the material of the substrate layer. Furthermore, in the same manner as in Example 1, the surface protection sheet of this example was obtained. The bending stiffness of the surface protection sheet in this example is 3.6×10 ^-4 Pa·m ³ at 25°C, the tensile elastic modulus at 25°C is 3.8×10 ⁹ Pa, and the stress at 100% elongation at 25°C is 157 N/mm ^2. The breaking stress at 25°C is 189 N/mm ² , and the breaking strain at 25°C is 175%.

<Examples 4 to 6> Except having used the adhesive agent layer E1 instead of the adhesive agent layer S1, it carried out similarly to Examples 1-3 respectively, and obtained the surface protection sheet of each example.

<Comparative Example 1> As the material of the substrate layer, an OPP film with a thickness of 12 μm (product name “Torayfan #12D-KW37”, manufactured by Toray Corporation, biaxially stretched PP film) was used. Furthermore, in the same manner as in Example 1, the surface protection sheet of this example was obtained. The bending stiffness of the surface protection sheet in this example at 25°C is 5.9×10 ^-7 Pa·m ³ , the tensile elastic modulus at 25°C is 3.6×10 ⁹ Pa, and the stress at 100% elongation at 25°C is 105 N/mm ^2. The breaking stress at 25°C is 156 N/mm ² , and the breaking strain at 25°C is 183%.

<Performance evaluation> For the surface protection sheet of each example, the adhesive force F0 [N/20 mm], the water peeling force FW0 [N/20 mm], and the starting point peeling force in water [N/10 mm] were measured. The results are shown in Table 1. In Table 1, the outline|summary of each example is shown together. Furthermore, the moisture permeability of the surface protection sheet of each example is within the range of ±1.5 g/(m ² ·day) of the moisture permeability of the substrate (layer).

[Table 1] Table 1 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Comparative example 1 adhesive layer type S1 S1 S1 E1 E1 E1 S1 aggregation method solvent solvent solvent lotion lotion lotion solvent Thickness [μm] 25 25 25 25 25 25 25 Substrate layer type OPP OPP PET OPP OPP PET OPP Thickness [μm] 60 25 100 60 25 100 12 Bending stiffness value [Pa・m ³ ] 1.2×10 ^-4 9.3×10 ^-6 3.6×10 ^-4 1.2×10 ^-4 9.3×10 ^-6 3.6×10 ^-4 5.9×10 ^-7 Adhesion force F0[N/20 mm] 8.2 6.8 8.0 8.1 8.0 7.8 6.0 Water peeling force FW0[N/20 mm] 0.4 0.2 0.1 0.1 0.0 0.1 0.4 Starting point peeling force in water[N/10 mm] 0.6 0.3 0.8 0.7 0.3 0.7 0.1

As shown in Table 1, the starting point peeling force in water of the surface protection sheets of Examples 1 to 6 whose bending stiffness at 25°C is in the range of 1.0×10 ^-6 to 1.0×10 ^-2 Pa·m ³ is all 0.2 N /10 mm or more, compared with Comparative Example 1 whose bending stiffness at 25°C was less than 1.0×10 ^-6 Pa·m ³ , the edge peeling resistance was excellent. Also, the water peeling force of the surface protection sheets of Examples 1 to 6 was reduced to 1.0 N/20 mm or less, and it can be seen that peeling can be achieved without damaging or deforming the adherend during peeling. From the above results, it can be seen that the surface protection sheet whose bending stiffness at 25°C is in the range of 1.0×10 ^-6 to 1.0×10 ^-2 Pa·m ³ and whose water peeling force FW0 is 1.0 N/20 mm or less can be used even in When used in a manufacturing process that includes the step of treating the object to be protected in a liquid in a state of being attached to the object to be protected, it is not easy to peel off from the end due to external forces such as vibration during the process. When peeling off, it is possible to peel off without damaging or deforming the object to be protected.

Furthermore, although not shown in the table, the adhesive force F1 of the surface protection sheet of Example 5 after immersion in warm water for 30 minutes was 1.4 N/20 mm, and the water peeling force FW1 after immersion in warm water for 30 minutes was 0.0 N/20 mm. 20 mm.

"Experiment 2" ＜Preparation of Adhesive＞ (Adhesive E2) With respect to 100 parts of the solid content of the aqueous dispersion of the acrylic polymer e1, an adhesion-imparting resin emulsion (manufactured by Arakawa Chemical Industry Co., Ltd., SUPER ESTER E-865NT, an aqueous dispersion of polymerized rosin ester with a softening point of 160°C, the following Sometimes expressed as "adhesion-imparting resin A"), the added amount was changed to 20 parts (solid content). In addition, an adhesive layer E2 having a thickness of 25 μm was obtained in the same manner as the preparation of the above-mentioned adhesive layer E1.

(Adhesive E3) Except for changing the solid content of the aqueous dispersion of the acrylic polymer e1 to 30 parts (solid content) per 100 parts of the tackifying resin A, the same method as that of the above-mentioned adhesive layer E2 was used. In this way, an adhesive layer E3 with a thickness of 25 μm was obtained.

(Adhesive E4) The monomer composition of the acrylic polymer was changed to 49 parts of 2EHA, 49 parts of n-butyl methacrylate (BMA), and 2 parts of AA, and 2 parts of anionic reactive emulsifier (first Industrial Pharmaceutical Co., Ltd., AQUALON BC2020) as an emulsifier. In addition, by the same method as the preparation of the acrylic polymer e1 in the adhesive E1, an aqueous emulsion of the monomer mixture (monomer emulsion) was prepared and polymerized to obtain an aqueous dispersion of the acrylic polymer e2 . After the system was cooled to normal temperature, for every 100 parts of the solid content of the aqueous dispersion of the above-mentioned acrylic polymer e2, 20 parts of the solid content of the adhesion-imparting resin A, oxazoline crosslinking agent (Nippon Shokubai Co., Ltd. Manufactured by the company, Epocros WS-500) 2 parts. Furthermore, the pH value was adjusted to about 7.5 and the viscosity was adjusted to about 9 Pa·s by using 10% ammonia water as a pH adjuster and polyacrylic acid (36% non-volatile matter aqueous solution) as a thickener. Emulsion adhesive composition E4. An adhesive layer E4 having a thickness of 25 μm was obtained in the same manner as the preparation of the aforementioned adhesive layer E2 except that the above-mentioned emulsion-type adhesive composition E4 was used.

(Adhesive E5) Adhesion-imparting resin B (manufactured by Arakawa Chemical Industry Co., Ltd., SUPER ESTER NS-121, aqueous dispersion of rosin-based resin (acid value imparting) with a softening point of 120° C.) was used as 20 parts in terms of solid content instead of 20 parts of adhesive-imparting resin A . In addition, an adhesive layer E5 having a thickness of 25 μm was obtained in the same manner as in the preparation of the adhesive layer E4.

(Adhesive E6) An adhesive layer E6 having a thickness of 25 μm was obtained in the same manner as the preparation of the adhesive layer E2 except that no tackifying resin was used.

(Adhesive E7) An adhesive layer E7 having a thickness of 25 μm was obtained in the same manner as the preparation of the adhesive layer E4 except that no tackifying resin was used.

(Adhesive S2) The solution containing the acrylic polymer s1 was obtained by the method described in the adhesive agent S1. In the solution obtained above, for every 100 parts of the monomer components used to prepare the solution, add maleylated rosin ester (manufactured by Harima Chemical Co., Ltd., HARITACK 4740, softening point 115 ~ 125°C, hereinafter sometimes referred to as "adhesion-imparting resin C") 20 parts based on solid content, isocyanate-based crosslinking agent (trimethylolpropane/xylylene diisocyanate adduct, manufactured by Mitsui Chemicals Co., Ltd. , trade name: Takenate D-110N, solid content concentration 75%) is 0.75 parts based on solid content basis, dioctyltin dilaurate (manufactured by Tokyo Fine Chemical Company, trade name: EMBILIZER OL) as crosslinking accelerator -1) 0.01 parts, 3 parts of acetylacetone as a crosslinking retarder and nonionic surfactant (polyoxyethylene sorbitan monolaurate, HLB16.7, trade name: RHEODOL TW -L120, manufactured by Kao Corporation) 0.5 part, and mixed uniformly to prepare solvent-type adhesive composition S2. The adhesive layer S3 with a thickness of 25 μm was obtained in the same manner as the preparation of the adhesive layer S2 except that the obtained solvent-based adhesive composition S2 was used.

(Adhesive S3～S4) The usage amount of the water affinity agent was changed from 0.3 part to 0.1 part (adhesive S3) or 0.5 part (adhesive S4) relative to 100 parts of the monomer component, and the same method as that of the adhesive layer S1 was used. In this way, adhesive layers S3 and S4 with a thickness of 25 μm were obtained.

<Examples 7 to 15> As the base layer material, an OPP film (product name "Torayfan #60-2500", manufactured by Toray Corporation, biaxially stretched PP film) with a thickness of 60 μm was prepared. Peel off the release liner covering one of the surfaces of the adhesive layers E2-E7 and S2-4 obtained above, and press a 2 kg rubber roller back and forth twice to press the exposed surface (adhesive surface) Attached to the surface of the above OPP film. In this way, the surface protection sheets (single-sided adhesive sheets with substrate layers) in which the adhesive surface was protected by a release liner were obtained. The bending stiffness at 25°C of the surface protection sheets of each example is 1.2×10 ^-4 Pa·m ³ , the stress at 100% elongation at 25°C is 83 N/mm ² , and the breaking stress at 25°C is 131 N/mm ² , 25 The breaking strain at ℃ is 232%.

＜Performance evaluation＞ For the surface protection sheet of each example, the adhesion force F0 [N/20 mm], water peeling force FW0 [N/20 mm], 20-degree starting point peeling force [N/10 mm] and rebound resistance (self-pressing Peeling length after 1 hour [mm]). The results are shown in Tables 2-3. The outline|summary of each example is shown together with Tables 2-3.

[Table 2] Table 2 Example 7 Example 8 Example 9 Example 10 Example 11 Example 12 adhesive layer type E2 E3 E4 E5 E6 E7 Polymer e1 e1 e2 e2 e1 e2 aggregation method lotion lotion lotion lotion lotion lotion Adhesion imparting agent [parts]* Adhesion Imparting Resin A 20 30 20 Adhesion Imparting Resin B 20 Thickness [μm] 25 25 25 25 25 25 Substrate layer type OPP OPP OPP OPP OPP OPP Thickness [μm] 60 60 60 60 60 60 Bending stiffness value [Pa・m ³ ] 1.2×10 ⁴ 1.2×10 ⁴ 1.2×10 ⁴ 1.2×10 ⁴ 1.2×10 ⁴ 1.2×10 ⁴ Adhesion force F0[N/20 mm] 8.1 8.2 5.5 10.4 5.9 5.1 Water peeling force FW0[N/20 mm] 0.1 0.1 0.1 0.4 0.3 0.1 20 degree starting point peeling force [N/10 mm] 0.7 0.7 0.7 0.8 0.3 0.3 Rebound resistance [mm] 0.0 0.0 0.0 0.0 0.8 1.0 *Parts relative to 100 parts of acrylic polymer

[table 3] table 3 Example 13 Example 14 Example 15 adhesive layer type S2 S3 S4 Polymer s1 s1 s1 aggregation method solvent solvent solvent Water affinity agent [parts]* 0.5 0.1 0.5 Adhesion imparting agent [parts]* 20 Thickness [μm] 25 25 25 Substrate layer type OPP OPP OPP Thickness [μm] 60 60 60 Bending stiffness value [Pa・m ³ ] 1.2×10 ⁴ 1.2×10 ⁴ 1.2×10 ⁴ Adhesion force F0[N/20 mm] 8.8 6.9 2.5 Water peeling force FW0[N/20 mm] 0.1 0.3 0.0 20 degree starting point peeling force [N/10 mm] 0.9 0.5 0.3 Rebound resistance [mm] 0.0 0.2 0.7 *Parts relative to 100 parts of acrylic polymer

As shown in Tables 2 to 3, the 20-degree starting point peeling force of the surface protection sheets of Examples 7 to 15 are all above 0.2 N/10 mm. It is less than 1.0 mm and has good anti-end peeling property. Among them, in Examples 7 to 12 using water-dispersed adhesives, the 20-degree starting point peeling force of Examples 7 to 10 with the addition of the adhesion imparting agent was higher than 0.5 N/10 mm, which was higher than that of the examples without the adhesion imparting agent. Compared with Examples 11-12, it is excellent in rebound resistance. Similarly, among Examples 13 to 15 using solvent-based adhesives, Example 13 with the addition of an adhesion-imparting agent and Example 14 with a reduced amount of water-affinity agent had a higher 20-degree starting point peeling force of 0.5 N/ 10 mm or more, compared with Example 15 in which no adhesion imparting agent was used and 0.5 parts of a water affinity agent was used, the rebound resistance was excellent. In Examples 7-10 and Examples 13-14, based on the adhesive, the 20-degree starting point peeling force is 0.5 N/10 mm or more, and exhibits more excellent rebound resistance. Also, according to the comparison between Example 14 and Example 15, if the usage amount of the water-affinity agent is increased, the water releasability is improved, but there is a tendency for the adhesive force F0 or the 20-degree starting point peeling force to decrease, and the anti-end peeling property also decreases. , but according to the results of Example 13, it can be seen that by using an adhesion imparting agent, even if a sufficient amount of a water affinity agent is used, the adhesive force F0 or the 20-degree starting point peeling force can be improved, so that a high level of adhesion during protection or protection can be achieved. End peeling resistance and water peeling removability.

Specific examples of the present invention have been described in detail above, but these are merely illustrations and do not limit the scope of claims. The technologies described in the claims include various modifications and changes of the specific examples illustrated above.

1: Surface protection sheet 1A: Then face 1B: back 2: Surface protection sheet 2A: Then face 2B: Back 10: Substrate layer 10A: one side 10B: The other side 11: The first floor 12: The second layer (the layer containing inorganic materials) 20: Adhesive layer 20A: Then face 30: Peel off the liner 50: Surface protection sheet with release liner

Fig. 1 is a cross-sectional view schematically showing an example of a surface protection sheet. Fig. 2 is a cross-sectional view schematically showing another example of the surface protection sheet.

1: Surface protection sheet

1A: Then face

1B: back

10: Substrate layer

10A: one side

10B: The other side

20: Adhesive layer

20A: Then face

30: Peel off the liner

50: Surface protection sheet with release liner

Claims (12)

A surface protection sheet whose bending stiffness at 25°C is in the range of 1.0×10 ^-6 to 1.0×10 ^-2 Pa·m ³ , and the water peeling force FW0 of the above surface protection sheet is 1.0 N/20 mm Hereinafter, the above-mentioned water peeling force FW0 refers to the bonded surface of the surface protection sheet attached to the surface of alkali glass having a water contact angle of 20 degrees or less, after being kept at 23°C and 50%RH for 1 hour, Supply 20 μL of distilled water between the soda glass and the bonding surface, and make the distilled water enter one end of the interface between the soda glass and the bonding surface, at a temperature of 23°C, a peeling angle of 180 degrees, and a speed of 300 mm/min. measured under the conditions. A surface protection sheet having a water peeling force FW0 of 1.0 N/20 mm or less, the above water peeling force FW0 being bonded to the surface of an alkali glass having a water contact angle of 20 degrees or less. After keeping the surface at 23°C and 50%RH for 1 hour, supply 20 μL of distilled water between the alkali glass and the bonding surface, and let the distilled water enter one end of the interface between the alkali glass and the bonding surface , measured at a temperature of 23°C, a peeling angle of 180 degrees and a speed of 300 mm/min. The starting point peeling force of the above-mentioned surface protection sheet is 0.5 N/10 mm or more, and the above-mentioned starting point peeling force is the adhesive surface of the surface of the alkali glass with a water contact angle of 20 degrees or less. After keeping it at 23°C and 50%RH for 24 hours, add 20 μL of distilled water dropwise between the alkali glass and the bonding surface, and perform the test at a temperature of 23°C, a peeling angle of 20° and a speed of 1000 mm/min. Determination. Such as the surface protection sheet of claim 1 or 2, wherein the above-mentioned water peeling force FW0 [N/20 mm] is less than 50% of the adhesive force F0 [N/20 mm], here, the above-mentioned adhesive force F0 is based on water The surface of alkali glass with a contact angle of 20 degrees or less is bonded to the bonding surface of the surface protection sheet, and after being kept at 23°C and 50%RH for 1 hour, it is peeled off at a temperature of 23°C, a peeling angle of 180° and a speed of Peel strength [N/20 mm] measured under the condition of 300 mm/min. The surface protection sheet according to any one of claims 1 to 3, comprising an adhesive layer and a substrate layer supporting the adhesive layer. The surface protection sheet according to claim 4, wherein the adhesive layer contains a water affinity agent. The surface protection sheet according to any one of Claims 1 to 5, which has a thickness of 20-200 μm. The surface protection sheet according to any one of Claims 1 to 6, which is used in the step of chemically and/or physically thinning a glass or a semiconductor wafer in a liquid. A treatment method is to deal with the adherend, including: A step of attaching a surface protection sheet to the surface of the adherend having a surface with a water contact angle of 20 degrees or less; a step of applying a physical load to the above-mentioned adherend to which the above-mentioned surface protection sheet is attached along the thickness direction of the surface protection sheet; and a step of peeling and removing the above-mentioned surface protection sheet from the above-mentioned adherend in the presence of water; and The water peeling force FW0 of the above-mentioned surface protection sheet is 1.0 N/20 mm or less, and the starting point peeling force is 0.5 N/10 mm or more, [Water Peeling Force FW0] The above-mentioned water peeling force FW0 refers to the bonded surface of the alkali glass with a surface with a water contact angle of 20 degrees or less, which is attached to the surface protection sheet. 20 μL of distilled water is supplied between the alkali glass and the bonding surface, and after the distilled water enters one end of the interface between the alkali glass and the bonding surface, the temperature is 23°C, the peeling angle is 180 degrees, and the speed is 300 mm/min. The measured water peeling force [N/20 mm]; [Peel force at starting point] The above-mentioned peeling force at the starting point is measured on the surface of alkali glass with a water contact angle of 20 degrees or less. The surface is attached to the surface protection sheet. After being kept at 23°C and 50%RH for 24 hours, the alkali Add 20 μL of distilled water dropwise between the glass and the bonding surface, and measure the maximum stress [N/10 mm] at the initial stage of peeling under the conditions of temperature 23°C, peeling angle 20 degrees, and speed 1000 mm/min. The processing method according to claim 8, wherein the water peeling force FW0 [N/20 mm] of the surface protection sheet is less than 50% of the adhesive force F0 [N/20 mm], [adherence F0] The above-mentioned adhesive force F0 refers to the bonding surface of the surface protection sheet of alkali glass with a water contact angle of 20 degrees or less. After keeping it at 23°C and 50%RH for 1 hour, it was tested at a temperature of 23°C. Peel strength [N/20 mm] measured under the conditions of ℃, peeling angle of 180 degrees and speed of 300 mm/min. The processing method according to claim 8 or 9, wherein the above-mentioned surface protection sheet comprises an adhesive layer and a substrate layer supporting the adhesive layer. The processing method according to any one of claims 8 to 10, wherein the step of applying a physical load to the above-mentioned adherend to which the above-mentioned surface protection sheet is attached along the thickness direction of the surface protection sheet is a conveying step or a physical processing step . A surface protection sheet, which is used in the treatment method according to any one of claims 8 to 11.

Images