TWI811296B - Adhesive sheet peeling method - Google Patents

Abstract

The invention provides a method for peeling off an adhesive sheet attached to a polarizing plate. The above-mentioned adhesive sheet has an adhesive layer, and the adhesive layer includes an A layer constituting at least one surface of the adhesive layer. The surface of the polarizing plate on the side where the adhesive sheet is attached is subjected to corona treatment or plasma treatment. The above-mentioned peeling method includes a water peeling step, which is to make the aqueous liquid follow the above-mentioned aqueous liquid while there is an aqueous liquid at the interface between the above-mentioned polarizing plate and the above-mentioned adhesive sheet at the peeling line of the above-mentioned adhesive sheet from the above-mentioned polarizing plate. The peeling front line moves to the interface and peels off the adhesive sheet from the polarizing plate.

Description

Adhesive sheet peeling method

The present invention relates to a method for peeling off adhesive sheets. The claims of this application are based on Japanese Patent Application No. 2018-018621 filed on February 5, 2018, Japanese Patent Application No. 2018-109385 filed on June 7, 2018, and Japanese Patent Application No. 2018-109385 filed on July 3, 2018. Priority is granted to Japanese Patent Application No. 2018-126577, and the entire contents of such application are incorporated into this specification by reference.

Generally speaking, adhesives (also called pressure-sensitive adhesives. The same applies below) have the following properties: They assume the state of a soft solid (viscoelastic body) in a temperature range near room temperature and are easily adhered by pressure. on the adherend. By effectively utilizing this property, adhesives are widely used in various fields in the form of an adhesive sheet with a support having an adhesive layer on the support, or in the form of a support-less adhesive sheet without a support. [Prior technical literature] [Patent Document]

Patent Document 1: Japanese Patent Application Publication No. 2005-148638

[Problem to be solved by the invention]

Adhesives are required to have various properties depending on their intended use. Among these characteristics, there is a tendency that if one characteristic is improved, another characteristic will be degraded, and it is difficult to achieve both at a high level. An example of characteristics that are in such a difficult-to-balance relationship is adhesion to the adherend and secondary processability. The above-mentioned secondary processing refers to the situation where adhesion failure (positional deviation, generation of wrinkles or bubbles, inclusion of foreign matter, etc.) occurs when the adhesive sheet is attached to the adherend, or when the adhesive sheet is attached. If any defect is found on the adherend, peel the adhesive sheet from the adherend and reattach it. Patent Document 1 discloses a method for peeling an adhesive optical film from a substrate with an adhesive optical film attached to the surface of a substrate (adherent) such as a glass substrate. A technique for peeling off the adhesive optical film from the substrate while a liquid exists at the peeling interface between the adhesive layer of the film and the substrate. On the other hand, Patent Document 1 does not examine the peeling method of the adhesive sheet attached to the polarizing plate, that is, the peeling method of the adhesive sheet when the adherend is a polarizing plate.

Therefore, an object of the present invention is to provide an adhesive sheet peeling method that can easily peel an adhesive sheet from a polarizing plate as an adherend using an aqueous liquid such as water. [Technical means to solve the problem]

According to this specification, a method for peeling off an adhesive sheet attached to a polarizing plate as an adherend is provided. The surface of the polarizing plate on the side where the adhesive sheet is attached is subjected to corona treatment or plasma treatment. The above-mentioned adhesive sheet has an adhesive layer, and the adhesive layer includes an A layer constituting at least the surface of the adhesive layer on the side of the polarizing plate. The peeling method may include a water peeling step, which involves causing the aqueous liquid to follow the aqueous liquid at the interface between the polarizing plate and the adhesive sheet at the peeling line of the adhesive sheet from the polarizing plate. The peeling front line moves to the interface and peels off the adhesive sheet from the polarizing plate. Here, the peeling front line refers to the position where the adhesive sheet starts to separate from the polarizing plate when the adhesive sheet is peeled from the polarizing plate. According to the above water peeling step, the above aqueous liquid can be effectively used to peel off the adhesive sheet from the polarizing plate. In some aspects, the above-mentioned A layer is preferably composed of an adhesive containing a water affinity agent.

The above-mentioned peeling method can be preferably carried out in a state in which the above-mentioned peeling front line is moved at a speed of 10 mm/min or more in the above-mentioned water peeling step. According to this aspect, the adhesive sheet can be efficiently peeled off from the polarizing plate.

Preferred embodiments of the present invention will be described below. Furthermore, those matters necessary for the implementation of the present invention other than those specifically mentioned in this specification can be understood by those skilled in the art based on the tips regarding the implementation of the invention described in this specification and the technical common sense at the time of filing the application. The present invention can be implemented based on the content disclosed in this specification and the technical common sense in this field. In addition, in the following drawings, members and parts that perform the same functions may be described with the same symbols attached, and repeated descriptions may be omitted or simplified. In addition, the embodiments described in the drawings are schematic for the purpose of clearly explaining the present invention, and do not necessarily accurately represent the dimensions or scale of actual products provided.

In this specification, the so-called "acrylic polymer" refers to a polymer derived from a monomer component containing more than 50% by weight of acrylic monomers. The acrylic monomer refers to a monomer derived from a monomer having at least one (meth)acrylyl group per molecule. In addition, in this specification, the term "(meth)acrylyl group" refers to a meaning including an acrylyl group and a methacrylyl group. Similarly, "(meth)acrylate" means acrylate and methacrylate, and "(meth)acrylic acid" means acrylic acid and methacrylic acid.

＜Construction example of adhesive sheet＞ An example of the structure of an adhesive sheet that can be used in the adhesive sheet peeling method disclosed herein is shown in FIG. 1 . The adhesive sheet 1 is constituted in the form of a single-sided adhesive sheet. The single-sided adhesive sheet includes a surface 10A that serves as an adhesion surface to a polarizing plate as an adherend (i.e., a polarizing plate). The adhesive layer 10 on one side of the adhesive layer 10 and the support 20 laminated on the other surface 10B of the adhesive layer 10 . The adhesive layer 10 is fixedly bonded to one surface 20A of the support 20 . As the support 20, for example, a plastic film such as a polyester film can be used. In the example shown in FIG. 1 , the adhesive layer 10 has a single-layer structure. That is, the entire adhesive layer 10 is composed of the A layer constituting one surface (adhesive surface) 10A of the adhesive layer 10 . The adhesive sheet 1 is used on a surface 10A on which a polarizing plate as an adherend is attached. The adhesive sheet 1 before use (before being attached to an adherend) may have an adhesive surface 10A protected by a release liner 30 with at least the adhesive layer side serving as a release surface (release surface) as shown in FIG. 1 . The form of the adhesive sheet 50 with a release liner. Alternatively, the second surface 20B of the support 20 (the surface opposite to the first surface 20A, also referred to as the back surface) may be a peeling surface, and the adhesive surface 10A may be in contact with the second surface. The adhesive surface 10A is protected by being wound or laminated in such a manner as to face 20B.

The release liner is not particularly limited. For example, a release liner whose surface is subjected to a release treatment of a liner base material such as a resin film or paper, or a release liner containing a fluorine-based polymer (polytetrafluoroethylene, etc.) or a polyolefin-based resin can be used. (Polyethylene, polypropylene, etc.) Release liners of low-adhesion materials, etc. In the above-mentioned peeling treatment, for example, a polysiloxane-based, long-chain alkyl-based, etc. peeling treatment agent can be used. In some aspects, a release-treated resin film may be preferably used as a release liner.

Another structural example of an adhesive sheet that can be used in the adhesive sheet peeling method disclosed herein is shown in FIG. 2 . The adhesive sheet 2 is constituted in the form of a single-sided adhesive sheet. The single-sided adhesive sheet includes an adhesive layer 110 with a surface 110A serving as an adhesion surface to the adherend, and an adhesive layer 110 laminated on the adherend. The other surface of the agent layer 110 is the support 20 . The adhesive layer 110 has a two-layer structure, and the two-layer structure includes an A layer 112 constituting a surface (adhesive surface) 110A, and a B layer 114 laminated on the back side of the A layer 112 . The adhesive sheet 2 before use (before being attached to the adherend) can be the same as the adhesive sheet 1 shown in FIG. 1 , with the adhesive surface 110A being protected by a release liner (not shown) with a release liner. The shape of the sheet. Alternatively, the second surface 20B of the support 20 may be a peeling surface, and the adhesive surface 110A may be protected by being wound or laminated so that the adhesive surface 110A is in contact with the second surface 20B.

The adhesive sheet that can be used in the adhesive sheet peeling method disclosed herein can also be in the form of a double-sided adhesive sheet containing an adhesive layer without a support. This kind of double-sided adhesive sheet without a support can be used by bonding a support to the other surface of the adhesive layer, for example.

The adhesive sheet peeling method disclosed herein can peel off the adhesive sheet from the member where one surface of the adhesive layer constituting the adhesive sheet (ie, the surface of the A layer) is attached to the member. Better implementation in this way. Here, the above-mentioned member is a polarizing plate, and more specifically, it is a polarizing plate in which the surface (attached surface) of the side to which the adhesive sheet is attached has been subjected to corona treatment or plasma treatment. Generally speaking, a polarizing plate has a polarizing film sandwiched between two pieces of triacetyl cellulose (TAC) film. It is preferable that at least the surface (attached surface) of the TAC film disposed on the side to which the adhesive sheet is attached is protected by a hard coat layer among the two TAC films. The above-mentioned hard coat layer is preferably composed of a urethane acrylate-based material. It may also be a polarizing plate in which an anti-reflection layer is further provided on the hard coat layer. For example, as shown in FIG. 3 , the above-mentioned member for attaching the adhesive sheet may be a surface 110A of the adhesive layer 110 of the adhesive sheet 2 shown in FIG. 2 (the surface on the polarizing plate side) attached to the member ( The component 200 of the adhesive sheet is made of a polarizing plate (70). It may also be an adhesive sheet member in which one surface 10A of the adhesive sheet 1 shown in FIG. 1 is attached to the member (polarizing plate) 70 instead of the adhesive sheet 2 shown in FIG. 2 .

＜Characteristics of adhesive sheet＞ The adhesive sheet that can be used in the peeling method of the present invention preferably has a water-resistant adhesive force reduction rate of less than 30%, and a water-repellent adhesive force reduction rate of more than 40%. The water-resistant adhesion reduction rate [%] is defined as the normal adhesion force N0 [N/10 mm] and the water-resistant adhesion force N1 [N/10 mm] and is calculated by (1-(N1/N0))×100 value. The water peel adhesion reduction rate [%] is defined as the value calculated based on the normal adhesion force N0 [N/10 mm] and the water peel force N2 by (1-(N2/N0))×100. The normal adhesion force N0, the water-resistant adhesion force N1 and the water peeling force N2 are measured by the following methods. The same measurement method can also be used in the following examples.

[Measurement of normal adhesion force N0] Cut the adhesive sheet to be measured into a rectangular shape with a width of 10 mm and a length of 120 mm to prepare a test piece. Use a hand roller to attach the A layer side of the above test piece to the adherend to prepare an evaluation sample. Put the evaluation sample into an autoclave and process it for 15 minutes at a pressure of 5 atm and a temperature of 50°C. . After maintaining the evaluation sample taken out from the autoclave for 1 day in an environment of 23°C and 50% RH, under the same environment, insert a cutting knife into the interface between the test piece and the adherend to shorten the length of the test piece. One end of the direction is peeled off from the adherend. According to JIS Z0237, a tensile testing machine is used to measure the peel strength under the conditions of a tensile speed of 300 mm/min and a peeling angle of 180 degrees.

[Measurement of water-resistant adhesion N1] Cut the adhesive sheet to be measured into a rectangular shape with a width of 10 mm and a length of 120 mm to prepare a test piece. Use a hand roller to attach the A layer side of the above test piece to the adherend to prepare an evaluation sample. Put the evaluation sample into an autoclave and process it for 15 minutes at a pressure of 5 atm and a temperature of 50°C. . The evaluation sample taken out from the autoclave was maintained in an environment of 23°C and 50% RH for 1 day, and then immersed in water at room temperature (23°C to 25°C) for 30 minutes. As water, ion-exchanged water or distilled water is used. In water, the sample for evaluation is held horizontally with the surface with the test piece attached facing upward. The distance (immersion depth) from the upper surface of the evaluation sample to the water surface is set to 10 mm or more (for example, about 10 mm to 100 mm). Then, the evaluation sample was lifted out of the water, and after gently wiping off the water adhering to the evaluation sample, a cutting knife was inserted into the interface between the test piece and the adherend to peel off one end of the test piece in the length direction. In an environment of 23°C and 50% RH, according to JIS Z0237, use a tensile testing machine to measure the peel strength at a tensile speed of 300 mm/min and a peel angle of 180 degrees. The time from when the evaluation sample is lifted out of water to when the peel strength is measured is within 10 minutes.

[Measurement of water peeling force N2] Cut the adhesive sheet to be measured into a rectangular shape with a width of 10 mm and a length of 120 mm to prepare a test piece. Use a hand roller to attach the A layer side of the above test piece to the adherend to prepare a sample for evaluation. Put the sample for evaluation into an autoclave and process it for 15 minutes at a pressure of 5 atm and a temperature of 50°C. . After maintaining the evaluation sample taken out from the autoclave for 1 day in an environment of 23°C and 50% RH, in the same environment, drop a drop on the surface of the adherend exposed from that end near one end of the length direction of the test piece. Add 1 drop (about 10 μl to about 40 μl) of distilled water. Then, after inserting a cutting knife into the interface between the test piece and the adherend to allow the above-mentioned water to enter the above-mentioned interface, a tensile testing machine was used according to JIS Z0237 at a tensile speed of 300 mm/ Minutes and a peeling angle of 180 degrees were used to measure the peel strength. Furthermore, the water used in the measurement of the water peel force N2 is only one drop of distilled water added to the adherend before peeling starts.

In the measurement of the above-mentioned normal adhesion force N0, water-resistant adhesion force N1 and water peeling force N2, as the adherend, a polarizing plate was used. The polarizing plate has a polarizing film sandwiched by two pieces of TAC film, and the adhesive sheet is attached. The surface on the side of the material (the surface to be attached) is a surface on which a hard coat layer and an anti-reflective layer as a protective layer are sequentially laminated on the TAC film, and corona treatment is performed on this surface (the surface to be attached). The corona treatment of the adherend surface is performed by placing the adherend at output setting 3 just before attaching the test piece to the adherend (typically, within 30 minutes before attachment). (Indicates 0.17 kW), passed through the "AGF-012" (desktop surface corona treatment device) manufactured by KASUGA once under the conditions of table speed scale 20 (equivalent to speed 3 m/min). The test piece is attached to the adherend in such a way that the distance from the outer peripheral end of the test piece to the outer peripheral end of the adherend is at least 10 mm or more, preferably 15 mm or more. In addition, as the tensile testing machine, a universal tensile and compression testing machine (device name "Tensile Compression Testing Machine, TCM-1kNB" manufactured by Minebea Co., Ltd.) or its equivalent can be used. The peel strength is measured by peeling off the test piece attached to the adherend from bottom to top. During measurement, if necessary, attach an appropriate substrate material to the back of the adhesive sheet (the surface opposite to the surface of layer A) to reinforce the test piece. As the substrate material, for example, a polyethylene terephthalate film with a thickness of about 25 μm can be used. Furthermore, regarding the adherend, as a substitute for the polarizing plate having the above structure, a TAC film that simulates the structure of the attached surface side of the polarizing plate, that is, having a hard coat layer and an anti-reflection layer laminated in sequence, can also be used. The surface is provided with a corona-treated TAC film under the above conditions. The above-mentioned hard coating layer and anti-reflection layer can be formed by the methods described in the following embodiments.

(Water peel adhesion reduction rate) The peeling method of the present invention is preferably applied to an adhesive sheet whose water peeling adhesive force reduction rate is more than 40%. An adhesive sheet showing such a water-peel adhesion reduction rate can be easily peeled from a polarizing plate by using an aqueous liquid such as water. For example, a small amount of aqueous liquid is supplied to an adherend (polarizing plate) to which an adhesive sheet is attached, and the aqueous liquid enters from one end of the adhesive sheet to the interface between the adhesive sheet and the adherend. By peeling off the adhesive sheet after the starting point of peeling, the peeling strength of the adhesive sheet from the adherend can be greatly reduced. This property can be used to achieve both high adhesion and good secondary processability during normal use. In certain aspects, the water peel adhesion reduction rate may be, for example, more than 50%, more than 65%, more than 75%, more than 85%, more than 90%, or more than Above 95%, it can also be above 97%. The water peel adhesion reduction rate is in principle less than 100%, but typically does not reach 100%.

(Water-resistant adhesion reduction rate) As mentioned above, it is preferable that the adhesive sheet to which the peeling method of the present invention is applied can be easily peeled off using an aqueous liquid such as water, and that the water-resistant adhesive force reduction rate is 30% or less. From the viewpoint of obtaining higher water-resistant reliability, the water-resistant adhesion force reduction rate is, for example, preferably 20% or less, more preferably 10% or less, and may be 7% or more. The water-resistant adhesion reduction rate is typically 0% or more. The difference between the water peeling adhesive force reduction rate [%] and the water-resistant adhesive force reduction rate [%] of the above-mentioned adhesive sheet is, for example, 45% or more, or 55% or more, or 70% or more, or 80% or more, or 90% The above aspects are preferably implemented.

From the perspective of joint reliability, the adhesive sheet using the peeling method disclosed in this article preferably has a normal adhesive force N0 of 2.0 N/10 mm or more. In certain aspects, the normal adhesion force N0 may be, for example, 2.5 N/10 mm or more, 3.0 N/10 mm or more, 3.5 N/10 mm or more, or 4.0 N/10 mm or more. The upper limit of the normal adhesion force N0 is not particularly limited, for example, it can be 30 N/10 mm or less. In some aspects, the normal adhesion force N0 may be less than 20 N/10 mm or less than 15 N/10 mm.

The water peeling force N2 is preferably 60% or less of the normal adhesion force N0, more preferably 50% or less. Although not particularly limited, the water peeling force N2 may be, for example, 10 N/10 mm or less, 3.5 N/10 mm or less, 2.5 N/10 mm or less, or 1.6 N/10 mm or less. It may be 1.2 N/10 mm or less, or it may be 1.0 N/10 mm or less. An adhesive sheet with a low water peeling force N2 can reduce the load exerted on the adherend when peeling off the adhesive sheet. This characteristic is particularly meaningful, for example, in the form of a polarizing plate peel-off adhesive sheet having a thin film such as a hard coat layer or an anti-reflective layer on its surface. For example, the adhesive sheet may preferably have a water peeling force N2 of 0.75 N/10 mm or less, or 0.50 N/10 mm or less, or 0.25 N/10 mm or less, or 0.15 N/10 mm or less. implementation. The lower limit of the water peeling force N2 is not particularly limited, and may be substantially 0 N/10 mm, or may exceed 0 N/10 mm. Furthermore, from the viewpoint of improving the secondary processability, an adhesive sheet that is peeled off from the adherend without leaving any adhesive on the adherend in the measurement of the water peeling force N2 is preferred. That is, an adhesive sheet excellent in non-paste residue is preferred. Whether there is any residual adhesive on the adherend can be determined, for example, by visually observing the adherend after peeling off the adhesive sheet.

The ratio of the water peeling force N2 [N/10 mm] to the normal adhesion force N0 [N/10 mm] (N2/N0) may be, for example, 1/2.5 or less, 1/5 or less, or 1/ Below 10. A smaller ratio (N2/N0) means that the water peeling force N2 is significantly lower than the normal adhesion force N0. The peeling method disclosed herein can be preferably implemented in the aspect of peeling off an adhesive sheet with a ratio (N2/N0) of 1/15 or less, 1/25 or less, or 1/35 or less from the polarizing plate. The upper limit of the ratio (N2/N0) is not particularly limited, but may be 1/200 or more, 1/150 or more, or 1/100 or more.

In the above-mentioned adhesive sheet, the adhesive forming layer A constituting at least the surface on the polarizing plate side of the adhesive layer is preferably water-insoluble. Based on the water-insoluble A layer, it is easy to obtain an adhesive sheet with a high water-resistant adhesive force N1 and a low water-resistant adhesive force reduction rate. It is also preferable that the A layer is water-insoluble in order to prevent the adhesive from remaining on the adherend during peeling using an aqueous liquid such as water. In addition, it is advantageous that the A layer is water-insoluble in terms of preventing the transparency of the adhesive sheet from being reduced due to water immersion or moisture in the environment.

The adhesive constituting layer A is preferably non-water-swellable. Based on the non-water-swellable A layer, it is easy to obtain an adhesive sheet with a high water-resistant adhesive force N1 and a low water-resistant adhesive force reduction rate. Furthermore, in peeling using an aqueous liquid such as water, a small amount of the aqueous liquid can be effectively utilized to exhibit good peeling properties. It is also preferable that layer A is non-water-swellable from the viewpoint of preventing adhesive from remaining on the adherend during peeling using an aqueous liquid. In addition, it is advantageous that the A layer is non-water-swellable in terms of preventing the transparency of the adhesive sheet from being reduced due to water immersion or moisture in the environment.

Here, in this specification, the term "water-insoluble adhesive" means that the gel fraction measured by the following method is 75% or more. In addition, the term "the adhesive is non-water-swellable" means that the swelling degree measured by the following method is 2 or less. That is, weigh about 0.5 g of the adhesive to be measured, and let its weight be W1. The adhesive was immersed in 500 ml of distilled water at room temperature (about 23°C) for 48 hours, then filtered through a nylon mesh, and the weight W2 of the adhesive containing water was measured. Thereafter, the adhesive was dried at 130° C. for 5 hours, and the nonvolatile matter weight W3 was measured. The gel fraction and swelling degree are calculated by the following formulas. Gel fraction [%] = (W3/W1) × 100 Swelling degree=W2/W1

In certain aspects, the gel fraction of layer A may be, for example, more than 80%, more than 90%, more than 95%, or more than 98%. The gel fraction of layer A is in principle less than 100%. Furthermore, in certain aspects, the swelling degree of layer A may be, for example, 1.7 or less, 1.5 or less, or 1.2 or less. The swelling degree of layer A is usually above 1.0, typically exceeding 1.0.

In an adhesive sheet in which the adhesive layer includes layer A and layer B arranged on the back side of layer A, the gel fraction of layer B is not particularly limited. In some aspects, the gel fraction of layer B is preferably equal to or greater than the gel fraction of layer A, and may also be higher than the gel fraction of layer A. The gel fraction of layer B may be, for example, 90% or more, 95% or more, 98% or more, or 99% or more. The gel fraction of layer B is in principle less than 100%. Moreover, the gel fraction of the entire adhesive layer may be, for example, 85% or more, 90% or more, 95% or more, 98% or more, or 99% or more. Furthermore, in the adhesive layer including only layer A, the gel fraction of the entire adhesive layer means the gel fraction of layer A.

In an adhesive sheet in which the adhesive layer includes an A layer and a B layer disposed on the back side of the A layer, the swelling degree of the B layer is not particularly limited. In some aspects, the swelling degree of the B layer is preferably equal to or lower than the swelling degree of the A layer, and may also be lower than the swelling degree of the A layer. The swelling degree of layer B may be, for example, 1.5 or less, 1.3 or less, or 1.1 or less. The swelling degree of layer B is usually above 1.0, typically exceeding 1.0. Moreover, the swelling degree of the entire adhesive layer may be, for example, 1.6 or less, 1.4 or less, 1.2 or less, or 1.1 or less. Furthermore, in the adhesive layer including only the A layer, the swelling degree of the entire adhesive layer means the swelling degree of the A layer.

Furthermore, the gel fraction or swelling degree of the adhesive to water can be appropriately determined by, for example, the composition of the monomer components, the weight average molecular weight of the polymer, the use of cross-linking agents or multifunctional monomers, etc. Make adjustments using general methods.

＜Adhesive layer＞ (1)A layer In the adhesive sheet peeled off by the peeling method disclosed herein, the A layer constituting at least the surface of the polarizing plate side of the adhesive layer may be selected from the group consisting of acrylic adhesives, rubber adhesives (natural rubber, Synthetic rubber systems, hybrid systems of these, etc.), polysilicone adhesives, polyester adhesives, urethane adhesives, polyether adhesives, polyamide adhesives, fluorine adhesives The adhesive layer is composed of one or two or more adhesives from various well-known adhesives. Here, the acrylic adhesive refers to an adhesive containing an acrylic polymer as a main component. Rubber adhesives and other adhesives also have the same meaning. Furthermore, the concept of polymers here also includes polymers with a relatively low degree of polymerization that are sometimes generally referred to as oligomers.

(Acrylic adhesive) From the viewpoint of transparency or weather resistance, in some aspects, an acrylic adhesive can be preferably used as the constituent material of the A layer.

As the acrylic adhesive, for example, a (meth)acrylic acid alkyl ester containing more than 50% by weight of a linear or branched alkyl group having a carbon number of 1 to 20 at the ester terminal is preferred. Acrylic polymer composed of monomer components. Hereinafter, a (meth)acrylic acid alkyl ester having an alkyl group with a carbon number of X or more and Y or less at the ester terminal may be expressed as "(meth)acrylic acid C _XY alkyl ester". In order to easily obtain a balance of characteristics, the ratio of C _1-20 alkyl (meth)acrylate in the entire monomer component may be, for example, 55% by weight or more, 60% by weight or more, or 70% by weight. %above. 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.

Non-limiting specific examples of the C _1-20 alkyl (meth)acrylate include: (meth)acrylic acid methyl ester, (meth)ethyl acrylate, (meth)propyl acrylate, (meth)acrylic acid propyl ester, (meth)acrylic acid ethyl ester, (meth)acrylic acid propyl ester, (meth)acrylic acid propyl ester Isopropyl acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, 2-butyl (meth)acrylate, 3-butyl (meth)acrylate, (meth)acrylic acid Amyl ester, isopentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, (meth)acrylate Base) isooctyl acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate Ester, dodecyl (meth)acrylate, tridecyl (meth)acrylate, myristyl (meth)acrylate, pentadecyl (meth)acrylate, (meth) Cetyl acrylate, heptadecyl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate, nonadecyl (meth)acrylate, (meth)acrylate base) Eicosanyl acrylate, etc.

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

In some aspects, the monomer component constituting the acrylic polymer may include C _4-18 alkyl (meth)acrylate at a ratio of 40% by weight or more. Since the monomer component contains a relatively large amount of alkyl (meth)acrylate having an alkyl group having 4 or more carbon atoms at the ester terminal, there is a tendency to form an acrylic polymer with high lipophilicity. Acrylic polymers with higher lipophilicity can easily form an adhesive layer with a lower water-resistant adhesive strength reduction rate. The proportion of C _4-18 alkyl (meth)acrylate in the monomer component 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 C _6-18 alkyl (meth)acrylate at a ratio above any of the lower limits mentioned above. In addition, from the viewpoint of improving the cohesion of the adhesive layer and preventing cohesion failure, the proportion of C _4-18 alkyl (meth)acrylate in the monomer component is usually appropriately set to 99.5% by weight or less. It may be 99% by weight or less, it may be 98% by weight or less, or it may be 97% by weight or less. It may also be a monomer component containing C _6-18 alkyl (meth)acrylate in a ratio below any of the upper limits mentioned above.

The monomer components constituting the acrylic polymer may include alkyl (meth)acrylate and, if necessary, other monomers (copolymerizable monomers) that can be copolymerized with alkyl (meth)acrylate. 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.

Non-limiting specific examples of the copolymerizable monomer include the following. Monomers containing carboxyl groups: 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 (meth)acrylic acid hydroxyalkyl esters such as 12-hydroxylauryl ester and (meth)acrylic acid (4-hydroxymethylcyclohexyl)methyl ester. Monomers containing sulfonic acid or phosphate groups: such as styrenesulfonic acid, allylsulfonic acid, sodium vinylsulfonate, 2-(meth)acrylamide-2-methylpropanesulfonic acid, (methyl ) Acrylamide propanesulfonic acid, (meth)acrylic acid sulfopropyl ester, (meth)acryloxynaphthalene sulfonic acid, acrylyl phosphate 2-hydroxyethyl ester, etc. Epoxy group-containing monomers: such as glycidyl (meth)acrylate or (meth)acrylic acid-2-ethyl glycidyl ether and other epoxy group-containing acrylates, allyl glycidyl ether, (methyl ) Glycidyl acrylate, etc. Monomers containing cyano groups: such as acrylonitrile, methacrylonitrile, etc. Monomers containing isocyanato 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(tert-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 amide 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)(methyl) N-hydroxyalkyl (meth)acrylamide, N-(3-hydroxybutyl)(meth)acrylamide, N-(4-hydroxybutyl)(meth)acrylamide, etc. Amides; monomers with alkoxy and amide 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-(meth)acrylamide, base) acrylyl 𠰌line, etc. Monomers containing amine groups: for example, aminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, and tert-butylaminoethyl (meth)acrylate. Monomers with epoxy groups: for example, glycidyl (meth)acrylate, methyl glycidyl (meth)acrylate, and 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-vinyl piperazole, N-vinylpyrrolidone, N-vinylpyrrole, N-vinylimidazole, N-vinylethazole, N-(meth)acrylyl-2-pyrrolidinone , N-(meth)acrylylpiperidine, N-(meth)acrylylpyrrolidine, 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lindione, N-vinylpyrazole, N-vinyliso㗁azole, N-vinylthiazole, N-vinylisothiazole, N-vinylpyridine, etc. (for example, N-vinyl-2-caprolactam and other lactams). Monomers with succinimide skeleton: such as N-(meth)acryloxymethylenesuccinimide, N-(meth)acryloxy-6-oxyhexamethylenesuccinimide Amine, N-(meth)acryl-8-oxyhexamethylenesuccinimide, etc. Maleimines: such as N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, N-benzene Maleic imide, etc. Iconidimines: such as N-methyl itonimide, N-ethyl itonimide, N-butyl itonimide, N-octyl itonimide, N- 2-Ethylhexyl Ikonimide, N-cyclohexyl Ikonimide, N-lauryl Ikonimide, etc. (Meth)acrylic acid aminoalkyl esters: such as (meth)acrylic acid aminoethyl ester, (meth)acrylic acid N,N-dimethylaminoethyl ester, (meth)acrylic acid N,N-dimethylaminoethyl Ethylaminoethyl, tert-butylaminoethyl (meth)acrylate. Monomers containing alkoxy groups: such as 2-methoxyethyl (meth)acrylate, 3-methoxypropyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, (meth)acrylate (meth)acrylic acid alkoxyalkyl esters such as propoxyethyl acrylate, butoxyethyl (meth)acrylate, ethoxypropyl (meth)acrylate, etc.; methoxyethylene glycol Alkoxyalkylene glycol (meth)acrylates such as (meth)acrylate and methoxypolypropylene glycol (meth)acrylate. Monomers containing alkoxysilyl groups: such as 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 3-(meth)acryloxypropyltriethoxysilane (Methyl)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: such as cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, isopropyl (meth)acrylate, dicyclopentyl (meth)acrylate ester, adamantyl (meth)acrylate, etc. (Meth)acrylates with aromatic hydrocarbon groups: 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 vinyl chloride or fluorine atoms, and (meth)acrylates containing halogen atoms such as polysilicon Oxy (meth)acrylate and other silicon atom-containing (meth)acrylate, (meth)acrylate obtained from terpene compound derivative alcohol, etc.

When such a copolymerizable monomer is used, the usage amount is not particularly limited, but is usually appropriately set to 0.01% by weight or more of the total monomer components. From the viewpoint of better exerting the use effect of the copolymerizable monomer, the usage amount of the copolymerizable monomer may be 0.1% by weight or more of the total monomer component, or may be 0.5% by weight or more. In addition, from the viewpoint of easily achieving a balance of adhesive properties, the usage amount of the copolymerizable monomer is usually appropriately set to 50% by weight or less of the total monomer components, and preferably 40% by weight or less.

In some aspects, the monomer component preferably includes a carboxyl-containing monomer. Preferable examples of the carboxyl group-containing monomer include acrylic acid (AA) and methacrylic acid (MAA). AA and MAA can also be used together. When AA and MAA are used together, the weight ratio (AA/MAA) is not particularly limited, but may be in the range of about 0.1 to 10, for example. In some aspects, the above weight ratio (AA/MAA) can 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, or may be about 3 or less.

By using carboxyl-containing monomers, aqueous liquids such as water can be quickly attached to the surface of layer A. This situation can contribute to the reduction of water peeling force N2. The usage amount of the carboxyl group-containing monomer 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 total monomer components. %above. Furthermore, 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. The content may be 3.0% by weight or less, or the content may be 2.5% by weight or less. It is preferable that the amount of the carboxyl group-containing monomer used is not too large from the viewpoint of suppressing the diffusion of water to the entire A layer and suppressing the decrease in the water-resistant adhesive force N1. In addition, it is advantageous that the amount of the carboxyl group-containing monomer used is not too large in order to prevent the water used for measuring the water peeling force N2 from being absorbed by the A layer and running out of water during peeling.

In some aspects, the monomer component may include a hydroxyl-containing monomer. By using hydroxyl-containing monomers, the cohesion or cross-linking density of the adhesive can be adjusted to increase the normal adhesive force N0. When using a hydroxyl-containing monomer, the usage amount is not particularly limited. For example, it may be 0.01% by weight or more, 0.1% by weight or more, or 0.5% by weight or more of the total monomer component. In addition, from the viewpoint of suppressing excessive water diffusion into the entire A layer, in some aspects, the usage amount of the hydroxyl-containing monomer is appropriately set to, for example, 40% by weight or less of the total monomer component, or may be set to 40% by weight or less. The content may be 30% by weight or less, 20% by weight or less, 10% by weight or less, 5% by weight or less, or 3% by weight or less. The peeling method disclosed herein can also be preferably implemented in an aspect where the adhesive sheet peeled off by the peeling method does not substantially use a hydroxyl-containing monomer as a monomer component of the A layer.

In some aspects, the monomer component may include an alkoxysilyl group-containing monomer. The alkoxysilyl group-containing monomer is typically an ethylenically unsaturated monomer having at least 1 (preferably 2 or more, such as 2 or 3) alkoxysilyl groups in one molecule, Specific examples are as described above. The above-mentioned alkoxysilyl group-containing monomer may be used alone or in combination of two or more. By using a monomer containing an alkoxysilyl group, a cross-linked structure formed by the condensation reaction of the silanol group (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 case where the monomer component contains an alkoxysilyl group-containing monomer, the proportion of the alkoxysilyl group-containing monomer in the entire monomer component can be, for example, 0.005% by weight or more, which is usually appropriate. Let it be 0.01% by weight or more. Furthermore, from the viewpoint of improving the adhesiveness of 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.

The composition of the monomer component can be such that the glass transition temperature (hereinafter, also referred to as "the glass transition temperature of the acrylic polymer") calculated by the Fox formula is -75°C or more and -10°C Set as follows. In some aspects, the glass transition temperature (Tg) of the above-mentioned acrylic polymer is suitably -20°C or lower, preferably -30°C or lower, more preferably -40°C or lower, further preferably -50°C or lower, For example, it may be -55°C or lower. When the Tg of the acrylic polymer becomes low, the adhesiveness of the A layer to the adherend tends to improve as a whole. The A layer, which has a high adhesion to the adherend, can easily prevent water from penetrating into the interface between the adherend and the A layer without intending to peel off the adhesive sheet. This characteristic may become advantageous from the viewpoint of improvement of the water-resistant adhesive force N1 or reduction of the water-resistant adhesive force reduction rate. In addition, from the viewpoint of easily increasing the normal adhesion force N0, the Tg of the acrylic polymer may be -70°C or higher, or -65°C or higher, for example.

Here, as shown below, the above-mentioned Fox formula is a relational formula between the Tg of the copolymer and the glass transition temperature Tgi of the homopolymer obtained by polymerizing each monomer constituting the copolymer individually. 1/Tg＝Σ(Wi/Tgi) Furthermore, in the above 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 publicly known documents is used. For example, regarding the monomers listed below, the following values are used for the glass transition temperature of the homopolymer of the monomer. 2-ethylhexyl acrylate -70℃ n-Butyl acrylate -55℃ Methyl methacrylate 105℃ Methyl acrylate 8℃ Acrylic 106℃ Methacrylic acid 228℃

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

Regarding the monomers whose glass transition temperature of the homopolymer is not described in the above-mentioned Polymer Handbook, the value obtained by the following measurement method is used (see Japanese Patent Application Publication No. 2007-51271). Specifically, in a reactor equipped with a thermometer, a stirrer, a nitrogen introduction pipe and a reflux cooling pipe, 100 parts by weight of the monomer, 0.2 parts by weight of azobisisobutyronitrile and 200 parts by weight of ethyl acetate as the polymerization solvent were added. The mixture was stirred for 1 hour while flowing nitrogen gas. After removing the 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 was cooled to room temperature to obtain a homopolymer solution with a solid content concentration of 33% by weight. Then, the homopolymer solution was cast-coated on a release liner and dried to prepare a test sample (sheet-shaped homopolymer) with a thickness of about 2 mm. The test sample was punched into a disc shape with a diameter of 7.9 mm, clamped between parallel plates, and a viscoelastic testing machine (ARES, manufactured by Rheometrics) was used to impart shear strain with a frequency of 1 Hz on one side and in the temperature range of -70 The viscoelasticity was measured in shear mode at a temperature rise rate of ∼150°C and 5°C/min, and the peak temperature of tan δ was set as the Tg of the homopolymer.

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

During polymerization, a known or commonly used thermal polymerization initiator or photopolymerization initiator may be used depending on the polymerization method or polymerization aspect. Such a polymerization initiator may be used alone or in combination of two or more thereof as appropriate.

The thermal polymerization initiator is not particularly limited. For example, azo-based polymerization initiators, peroxide-based initiators, redox-based initiators obtained by combining a peroxide and a reducing agent, and substituted polymerization initiators can be used. Ethane starter, etc. More specifically, examples include: 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 Starting agents; such as potassium persulfate, ammonium persulfate and other persulfates; peroxide-based starting agents such as benzyl peroxide, tert-butyl hydroperoxide, hydrogen peroxide; such as phenyl-substituted ethane, etc. Substituted ethane-based initiators; for example, redox-based initiators such as a combination of persulfate and sodium bisulfite, a combination of peroxide and sodium ascorbate, etc., but are not limited to these. In addition, thermal polymerization can be preferably carried out at a temperature of about 20 to 100°C (typically 40 to 80°C).

The photopolymerization initiator is not particularly limited. For example, ketal-based photopolymerization initiators, acetophenone-based photopolymerization initiators, benzoin ether-based photopolymerization initiators, and acylphosphine oxide-based photopolymerization initiators can be used. Initiator, α-ketol photopolymerization initiator, aromatic sulfonyl chloride photopolymerization initiator, photoactive oxime photopolymerization initiator, benzoin photopolymerization initiator, benzoyl photopolymerization initiator Polymerization initiator, benzophenone photopolymerization initiator, 9-oxosulfide It is a photopolymerization initiator, etc.

The usage amount of such thermal polymerization initiator or photopolymerization initiator can be a usual usage amount corresponding to the polymerization method, polymerization state, etc., and is not particularly limited. For example, the polymerization initiator can be used in 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) relative to 100 parts by weight of the monomer to be polymerized.

In the above-mentioned polymerization, various previously known chain transfer agents (which can also be understood as molecular weight regulators or polymerization degree regulators) may be used if necessary. As the chain transfer agent, thiols such as n-dodecylmercaptan, tertiary-dodecylmercaptan, and thioglycolic acid can be used. Alternatively, a chain transfer agent containing no sulfur atoms (non-sulfur chain transfer agent) may also be used. Specific examples of non-sulfur chain transfer agents include: anilines such as N,N-dimethylaniline and N,N-diethylaniline; terpenes such as α-pinene and terpinene; α- Styrenes such as methylstyrene and α-methylstyrene dimer; compounds with benzylidene groups such as dibenzylidene acetone, cinnamyl alcohol and cinnamaldehyde; paraphenyls such as hydroquinone and dihydroxynaphthalene Phenols; quinones such as benzoquinone and naphthoquinone; olefins such as 2,3-dimethyl-2-butene, 1,5-cyclooctadiene; alcohols such as phenol, benzyl alcohol, allyl alcohol; Benzyl hydrogens such as phenylbenzene and triphenylbenzene, etc. A chain transfer agent can be used individually by 1 type or in combination of 2 or more types. When a chain transfer agent is used, the usage amount can be, for example, about 0.01 to 1 part by weight relative to 100 parts by weight of the monomer component. The techniques disclosed herein may also be better implemented without the use of chain transfer agents.

In some preferred aspects of the peeling method disclosed herein, the adhesive sheet has an A layer formed of a water-dispersed adhesive composition. Typical examples of water-dispersed adhesive compositions include emulsion-type adhesive compositions. The emulsion-type adhesive composition typically contains a polymer as a monomer component and optional additives.

Emulsion polymerization of monomer components is usually carried out in the presence of emulsifiers. The emulsifier for emulsion polymerization is not particularly limited, and known anionic emulsifiers, nonionic emulsifiers, etc. 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 dodecyl benzene sulfonate, polyoxyethylene sodium lauryl sulfate, and polyoxyethylene sodium alkyl ether sulfate. , polyoxyethylene alkyl phenyl ether ammonium sulfate, polyoxyethylene alkyl phenyl ether sodium sulfate, polyoxyethylene alkyl sodium sulfosuccinate, etc. Non-limiting examples of nonionic emulsifiers include polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene fatty acid esters, polyoxyethylene polyoxypropylene block polymers, and the like. Emulsifiers having reactive functional groups (reactive emulsifiers) can also be used. Examples of reactive emulsifiers include radically polymerizable emulsifiers in which a radically polymerizable functional group such as an acryl group or an allyl ether group is introduced into the above-mentioned anionic emulsifier or nonionic emulsifier. agent.

The amount of emulsifier used in emulsion polymerization may be, for example, 0.2 parts by weight or more, 0.5 parts by weight or more, 1.0 parts by weight or more, or 1.5 parts by weight or more, based on 100 parts by weight of the monomer component. In addition, from the viewpoint of improving the water-resistant adhesive force N1, reducing the water-resistant adhesive force reduction rate, or improving the transparency of the adhesive layer, in some aspects, the usage amount of the emulsifier is usually 100% of the monomer component. The part by weight is suitably 10 parts by weight or less, preferably 5 parts by weight or less, and may be 3 parts by weight or less. Furthermore, the emulsifier used in the emulsion polymerization here can also function as the water affinity agent of the A layer.

Emulsion polymerization can obtain a polymerization reaction liquid in the form of an emulsion in which the polymer of the monomer component is dispersed in water. The water-dispersed adhesive composition used to form layer A can be preferably produced using the above-mentioned polymerization reaction liquid.

In some aspects, the adhesive sheet may have an A layer formed from a solvent-based adhesive composition. Solvent-based adhesive compositions typically contain a solution polymer of monomer components and optional additives. The solvent (polymerization solvent) used for solution polymerization can be appropriately selected from previously known organic solvents. For example, aromatic compounds (typically aromatic hydrocarbons) selected from the group including toluene; 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 isopropyl alcohol (such as monohydric alcohols with 1 to 4 carbon atoms); ethers such as tert-butyl methyl ether; ketones such as methyl ethyl ketone Any one solvent or a mixture of two or more solvents. According to solution polymerization, a polymerization reaction liquid in a form in which a polymer of monomer components is dissolved in a polymerization solvent can be obtained. The solvent-based adhesive composition used to form layer A can be preferably produced using the above-mentioned polymerization reaction liquid.

In some aspects, the adhesive sheet may have an A layer formed of an active energy ray curable adhesive composition. Here, in this specification, "active energy rays" refer to energy rays having energy that can cause chemical reactions such as polymerization reaction, cross-linking reaction, and decomposition of the initiator. Examples of active energy rays here include light such as ultraviolet rays, visible rays, infrared rays, or radiation such as alpha rays, beta rays, gamma rays, electron beams, neutron beams, and X-rays. A preferred example of the active energy ray curable adhesive composition is a photocurable adhesive composition. The photocurable adhesive composition has the advantage that even a thick adhesive layer can be easily formed. Among them, an ultraviolet curable adhesive composition is preferred.

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 component). The polymerization method for forming the above-mentioned polymer is not particularly limited, and various conventionally 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 carried out by irradiation with light such as ultraviolet rays (typically carried out in the presence of light) can be suitably used. in the presence of a polymerization initiator); radiation polymerization by irradiating β-rays, γ-rays and other radiation. Among them, photopolymerization is preferred.

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

The polymerization conversion rate of the monomer mixture in the above-mentioned partial polymer is not particularly limited. The polymerization conversion rate can be, for example, about 70% by weight or less, preferably about 60% by weight or less. From the viewpoint of ease of preparation or coating properties of the adhesive composition containing the above-mentioned partial polymer, the polymerization conversion rate is generally about 50% by weight or less, preferably about 40% by weight or less (for example, about 35% by weight). %the following). The lower limit of the polymerization conversion rate is not particularly limited, but is typically about 1% by weight or more, and is usually appropriately set to about 5% by weight or more.

The adhesive composition containing a partial polymer of the monomer component can be prepared, for example, by using a suitable polymerization method (such as a photopolymerization method) to make a monomer mixture containing the entire amount of the monomer component used to prepare the adhesive composition. Obtained by partial aggregation. Furthermore, the adhesive composition containing a partial polymer of the monomer component may also be a partial polymer or a complete polymer containing a monomer mixture of a part of the monomer components used to prepare the adhesive composition, and the remaining A mixture of monomer components or partial polymers thereof. In addition, in this specification, the so-called "complete polymer" means that the polymerization conversion rate exceeds 95% by weight.

The adhesive composition containing the above-mentioned partial polymers can be formulated with other components (such as photopolymerization initiator, multifunctional monomer, cross-linking agent, water affinity agent, etc.) used as needed. The method of preparing such other components is not particularly limited. For example, they may be contained in the above-mentioned monomer mixture in advance, or may be added to the above-mentioned partial polymer.

(water affinity agent) In the peeling method disclosed herein, the adhesive sheet is preferably such that the A layer constituting one surface of the adhesive layer contains a water affinity agent in addition to the polymerization reactant of the monomer component. For example, an adhesive sheet preferably includes an A layer containing an acrylic polymer as the polymerization reactant and further containing a water affinity agent.

As the water affinity agent, various materials that can play a role of improving the water affinity of the surface of the A layer when contained in the A layer can be appropriately selected and used. By increasing the water affinity of the A layer, aqueous liquids such as water can be more quickly affined with the surface of the A layer. By this, for example, when measuring the water peeling force N2, the first drop of water can be made to follow the movement of the peeling line of the adhesive sheet from the adherend and spread across the surface of the A layer, which can effectively reduce the water peeling force N2. . Through the same effect, in the adhesive sheet peeling method that involves allowing an aqueous liquid such as water to enter the interface between the adhesive sheet and the adherend and moving the peeling front line, the adhesive sheet can be improved from the adherend. Peelability.

As the water affinity agent, known anionic surfactants, nonionic surfactants, cationic surfactants, water-soluble plasticizers, water-soluble polymers, etc. can be used. The water affinity agent can be used alone or in combination of two or more types.

As water-soluble plasticizers, various polyols (preferably polyether polyols) can be used. Specific examples thereof include polyethylene glycol, polypropylene glycol, polyoxypropylene sorbitol ether, polyglycerin, and the like. These can be used individually by 1 type or in combination of 2 or more types. Examples of the water-soluble polymer include polyvinyl alcohol, polyvinylpyrrolidone, polyacrylic acid, and the like.

Examples of anionic surfactants include alkyl benzene sulfonates such as sodium dodecyl benzene sulfonate; alkyl sulfates such as sodium lauryl sulfate and ammonium lauryl sulfate; polyoxyethylene laurylamine, polyoxyethylene lauryl sulfate, etc. Polyether amines such as ethylene stearylamine; polyether sulfates such as polyoxyethylene alkyl ether sodium sulfate, polyoxyethylene alkyl phenyl ether ammonium sulfate, polyoxyethylene alkyl phenyl ether sodium sulfate; polyoxyethylene stearyl ether phosphate Polyoxyethylene alkyl ether phosphate esters such as polyoxyethylene lauryl ether phosphate ester; polyoxyethylene alkyl ether phosphate ester salts such as sodium salt and potassium salt of the above-mentioned polyoxyethylene alkyl ether phosphate ester; polyoxyethylene alkyl ether phosphate esters Sodium sulfosuccinate, etc.

Examples of the nonionic surfactant include polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene glyceryl ether, polyoxypropylene glyceryl ether, polyoxyethylene bisphenol A ether and other polyoxyethylene surfactants. Alkyl ether; polyoxyethylene fatty acid ester, polyoxyethylene-polyoxypropylene block polymer, etc.

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, surfactants having a -POH group are preferred. This kind of surfactant typically contains a phosphate ester structure, for example, it can be 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 group), a mixture of both monoester and diester, etc. Preferable examples of the surfactant having a -POH group include polyoxyethylene alkyl ether phosphate. The number of carbon atoms of the alkyl group in the polyoxyethylene alkyl ether phosphate ester can be, for example, 6 to 20, 8 to 20, 10 to 20, 12 to 20, or 14 to 20 .

The content of the water affinity agent in layer A is not particularly limited. In some aspects, the content of the water affinity agent may be, for example, 0.2 parts by weight or more per 100 parts by weight of the monomer components constituting the polymer contained in the A layer. From the perspective of obtaining higher effects, The amount may be 0.5 parts by weight or more, the amount may be 1.0 parts by weight or more, or the amount may be 1.5 parts by weight or more. Furthermore, from the viewpoint of suppressing excessive water diffusion into the entire A layer, in some aspects, the usage amount of the water affinity agent is preferably 10 parts by weight or less based on 100 parts by weight of the monomer component. In order to set it to 5 parts by weight or less, you may set it to 3 parts by weight or less. It is also preferable that the content of the water affinity agent is not more than that of the water-resistant adhesive force N1 from the viewpoint of improving the water-resistant adhesive force N1, reducing the water-resistant adhesive force reduction rate, or improving the transparency of the adhesive layer.

(silane coupling agent) In some aspects, layer A can contain a silane coupling agent. According to the A layer containing a silane coupling agent, an adhesive sheet with a low water-resistant adhesive force reduction rate and a high water peeling adhesive force reduction rate can be better realized.

Examples of silane coupling agents include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyl Trimethoxysilane and other silicon compounds with epoxy structure; 3-aminopropyltrimethoxysilane, N-(2-aminoethyl)3-aminopropyltrimethoxysilane, N-(2 -Aminoethyl) 3-aminopropylmethyldimethoxysilane and other amine-containing silicon compounds; 3-chloropropyltrimethoxysilane; acetylacetyl-containing trimethoxysilane, 3 - Silane coupling agents containing (meth)acrylyl groups such as acryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane; 3-isocyanatopropyltriethoxysilane Ethoxysilane and other isocyanate-containing silane coupling agents. Among them, preferred examples include 3-glycidoxypropyltrimethoxysilane and acetoacetyl group-containing trimethoxysilane.

The usage amount of the silane coupling agent is set in such a way that the desired effect can be obtained and is not particularly limited. In some aspects, the usage amount of the silane coupling agent may be, for example, 0.001 parts by weight or more relative to 100 parts by weight of the monomer component constituting the polymer contained in the A layer. From the perspective of obtaining higher effects, The amount may be 0.005 parts by weight or more, the amount may be 0.01 parts by weight or more, or the amount may be 0.015 parts by weight or more. Furthermore, from the viewpoint of improving the adhesion with the adherend, in some aspects, the usage amount of the silane coupling agent may be, for example, 3 parts by weight or less based on 100 parts by weight of the monomer components constituting the layer A. It may be 1 part by weight or less, or it may be 0.5 part by weight or less.

Furthermore, in the case where the monomer component includes an alkoxysilyl group-containing monomer, the above-mentioned alkoxysilyl group-containing monomer can also be used as part or all of the silane coupling agent contained in the A layer.

(cross-linking agent) The A layer may contain a cross-linking agent if necessary. The type of cross-linking agent is not particularly limited, and for example, an appropriately selected cross-linking agent from previously known cross-linking agents can be used. Specific examples of the cross-linking agent include: isocyanate-based cross-linking agents, epoxy-based cross-linking agents, oxazoline-based cross-linking agents, aziridine-based cross-linking agents, carbodiimide-based cross-linking agents, Melamine cross-linking agents, urea cross-linking agents, metal alkoxide cross-linking agents, metal chelate cross-linking agents, metal salt cross-linking agents, hydrazine cross-linking agents, amine cross-linking agents, etc. These can be used individually by 1 type or in combination of 2 or more types.

As an example of the isocyanate-based cross-linking agent, a polyfunctional isocyanate compound having two or more functions can be used. Examples include: aromatic isocyanates such as toluene diisocyanate, xylene diisocyanate, polymethylene polyphenyl diisocyanate, tris(p-isocyanatophenyl)thiophosphate, diphenylmethane diisocyanate; isocyanate; Alicyclic isocyanates such as phorone diisocyanate; aliphatic isocyanates such as hexamethylene diisocyanate. Examples of commercially available products include: trimethylolpropane/toluene diisocyanate trimer adduct (manufactured by Tosoh Corporation, trade name "Coronate L"), trimethylolpropane/hexamethylene diisocyanate trimer adduct Polymer adducts (manufactured by Tosoh Corporation, trade name "Coronate HL"), isocyanate adducts such as hexamethylene diisocyanate isocyanurate (manufactured by Tosoh Corporation, trade name "Coronate HX"), etc. . In a water-dispersed adhesive composition, it is preferred to use an isocyanate cross-linking agent that is soluble or dispersed in water. For example, water-soluble, water-dispersible or self-emulsifying isocyanate cross-linking agents can be preferably used. It is preferable to use a so-called blocked isocyanate type isocyanate cross-linking agent in which the isocyanate group is blocked.

As the epoxy cross-linking agent, those having two or more epoxy groups per molecule can be used without particular limitation. An epoxy cross-linking agent having 3 to 5 epoxy groups per molecule is preferred. Specific examples of the epoxy cross-linking agent 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 cross-linking agents include: "TETRAD-X" and "TETRAD-C" manufactured by Mitsubishi Gas Chemical Company, trade names "EPICLON CR-5L" and Nagase ChemteX manufactured by DIC Corporation The product is manufactured under the trade name "DENACOL EX-512" by the company, and the product is manufactured under the trade name "TEPIC-G" by Nissan Chemical Industries, Ltd. In the water-dispersed adhesive composition, it is preferable to use an epoxy cross-linking agent that can be dissolved or dispersed in water.

As the tetrazoline cross-linking agent, those having one or more tetrazoline groups per molecule can be used without particular limitation. In the water-dispersed adhesive composition, it is preferred to use a tetrazoline-based cross-linking agent that is soluble or dispersed in water. Examples of aziridine-based crosslinking agents include: trimethylolpropane tris[3-(1-aziridinyl)propionate], trimethylolpropane tris[3-(1-(2 -Methyl)aziridinylpropionate)], etc. As the carbodiimide cross-linking agent, a low molecular compound or a high molecular compound having two or more carbodiimide groups can be used. In the water-dispersed adhesive composition, it is preferred to use a carbodiimide cross-linking agent that is soluble or dispersed in water.

In some aspects, peroxides can also be used as cross-linking agents. Examples of the peroxide include di(2-ethylhexyl)peroxydicarbonate, di(4-tert-butylcyclohexyl)peroxydicarbonate, dibutyl peroxydicarbonate, and peroxydicarbonate. Oxidized tert-butyl neodecanoate, tert-hexyl peroxypivalate, tert-butyl peroxypivalate, dilauryl peroxide, di-n-octyl peroxide, isobutyric peroxide 1,1 ,3,3-tetramethylbutyl ester, dibenzoyl peroxide, etc. Among them, examples of peroxides having particularly excellent crosslinking reaction efficiency include di(4-tert-butylcyclohexyl)peroxydicarbonate, dilauryl peroxide, dibenzoyl peroxide, etc. . Furthermore, when peroxide is used as the above-mentioned polymerization initiator, the remaining peroxide that has not been used for the polymerization reaction may be used for the cross-linking reaction. In this case, the remaining amount of peroxide is quantified, and when the ratio of peroxide does not reach a specific amount, peroxide may be added to achieve a specific amount if necessary. Quantification of peroxide can be performed by the method described in Japanese Patent No. 4971517.

The content of the cross-linking agent (the total amount of equal amounts when two or more cross-linking agents are included) is not particularly limited. From the viewpoint of realizing an adhesive that exhibits well-balanced adhesive properties such as adhesive force and cohesive force, the content of the cross-linking agent is usually appropriately set to about 5 parts by weight relative to 100 parts by weight of the monomer components contained in the adhesive composition. parts or less, preferably about 0.001 to 5 parts by weight, more preferably about 0.001 to 4 parts by weight, still more preferably about 0.001 to 3 parts by weight. Alternatively, it may be an adhesive composition that does not contain the cross-linking agent as described above. Alternatively, it may be an adhesive composition that does not contain the cross-linking agent as described above.

(Tackiness imparting resin) The A layer may also contain an adhesion-imparting resin. Examples of the tackifier resin include petroleum-based tackifier resins including rosin-based tackifier resins and rosin derivative tackifier-imparting resins, terpene-based tackifier-imparting resins, phenol-based tackifier-imparting resins, ketone-based tackifier-imparting resins, and the like. These can be used individually by 1 type or in combination of 2 or more types.

Examples of the rosin-based adhesion-imparting resin include rosins such as rosin gum, wood rosin, and tall oil rosin, as well as stabilized rosins (for example, stabilized rosins obtained by disproportionating or hydrogenating the above rosins), and polymerized rosins. (For example, the above-mentioned rosin polymer, typically dimer), modified rosin (for example, modified by unsaturated acids such as maleic acid, fumaric acid, (meth)acrylic acid, etc. Unsaturated acid modified rosin, etc.). Examples of the rosin derivative tackifier-imparting resin include esterified products of the rosin-based tackifier-imparting resin (for example, rosin esters such as stabilized rosin ester or polymerized rosin ester), and phenol-modified products of the above-mentioned rosin-based resin (phenol). Modified rosin) and its esterification products (phenol modified rosin ester), etc. Examples of the petroleum-based tackifier-imparting resin include aliphatic petroleum resins, aromatic petroleum resins, copolymerized petroleum resins, alicyclic petroleum resins, and hydrogenated products thereof. Examples of the terpene-based tackifier-imparting resin include α-pinene resin, β-pinene resin, aromatic modified terpene-based resin, terpene phenol resin, and the like. Examples of the ketone-based tackifier-imparting resin include ketones (for example, aliphatic ketones such as methyl ethyl ketone, methyl isobutyl ketone, and acetophenone; esters such as cyclohexanone and methylcyclohexanone). Ketone resins, etc. obtained by the condensation of cyclic ketones, etc.) and formaldehyde.

In some aspects, as the tackifier-imparting resin, one or two or more types selected from the group consisting of rosin-based tackifier-imparting resins, rosin derivative tackifier-imparting resins, and terpene phenol resins can be preferably used. Among them, rosin derivative adhesion-imparting resins are preferred, and preferred examples include rosin esters such as stabilized rosin ester and polymerized rosin ester.

In the water-dispersed adhesive composition, it is preferable to use a water-dispersed tackifying resin in a form in which the tackifying resin as described above is dispersed in an aqueous solvent. For example, by mixing an aqueous dispersion of an acrylic polymer and 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 adhesive-imparting resin, from the viewpoint of environmental hygiene, etc., it is preferable to use one that at least substantially does not contain aromatic hydrocarbon solvents. It is more preferable to use a water-dispersed adhesive-imparting 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" manufactured by Arakawa Chemical Co., Ltd. ESTER E-865NT", etc., or the trade names "HARIESTER SK-90D", "HARIESTER SK-70D", "HARIESTER SK-70E", "NEOTOL 115E", etc. manufactured by Harima Chemical Co., Ltd. In addition, commercially available products of terpene phenol resin (which may be in the form of water-dispersed terpene phenol resin) include: "TAMANOL E-100" and "TAMANOL E-200" manufactured by Arakawa Chemical Industry Co., Ltd. ”, “TAMANOL E-200NT”, etc.

The softening point of the adhesive imparting resin is not particularly limited. From the viewpoint of suppressing a decrease in the cohesive force of the adhesive layer, it is generally preferable to use an adhesive-imparting resin having a softening point of 80° C. or higher. The softening point of the adhesion imparting resin may be 90°C or higher, 100°C or higher, 110°C or higher, or 120°C or higher. Adhesion-imparting resins with softening points above 130°C or above 140°C can also be used. In addition, from the viewpoint of transparency or adhesion to an adherend, an adhesion-imparting resin having a softening point of 200° C. or lower or 180° C. or lower can be preferably used. In addition, as the softening point of the so-called tackifier-imparting resin here, the nominal value described in documents, catalogs, etc. can be used. When there is no nominal value, the softening point of the adhesion-imparting resin can be measured based on the softening point test method (ball and ball method) specified in JIS K5902 or JIS K2207.

From the viewpoint of better exerting its use effect, the usage amount of the tackifier resin is usually appropriately set to 1 part by weight or more based on 100 parts by weight of the monomer components constituting the polymer contained in the A layer, and may also be It may be 5 parts by weight or more, it may be 10 parts by weight or more, it may be 15 parts by weight or more, it may be 20 parts by weight or more, it may be 25 parts by weight or more. In addition, from the viewpoint of achieving a good balance between the adhesion to the adherend and the cohesiveness, the usage amount of the tackifying resin may be, for example, 70 parts by weight or less, or 50 parts by weight relative to 100 parts by weight of the monomer component. parts or less, or less than 40 parts by weight. Alternatively, the layer A may be substantially free of adhesion-imparting resin.

In some aspects of the peeling method disclosed herein, the water-resistant reliability of the adhesive sheet can be further improved by subjecting the adhesive sheet to a treatment that increases the water peeling force at a desired time point. An adhesive sheet exhibiting such properties can be realized in a structure in which layer A contains an adhesive imparting resin, for example, but is not limited to this structure. The treatment to increase the water peeling force may be, for example, a treatment in which a temperature higher than room temperature is applied after the adhesive sheet is attached to the adherend. The applied temperature is not particularly limited and can be selected considering workability, economy, convenience, heat resistance of the adhesive sheet or adherend, etc. The temperature may be, for example, 45°C or higher, or 55°C or higher. In addition, the temperature may be less than 150°C, may be 120°C or lower, may be 100°C or lower, or may be 80°C or lower, for example. The time for applying the above temperature is not particularly limited. For example, it can be more than 1 hour, more than 3 hours, or more than 1 day. Alternatively, the above-mentioned temperature can be applied for a longer period of time as long as the adhesive sheet or adherend does not undergo significant thermal deterioration. In some aspects, from the perspective of processing efficiency, the time for applying the above temperature can be set to within 14 days, or within 7 days, for example. The above temperature can be applied once or divided into multiple applications.

The water peeling force N3 of the adhesive sheet after the treatment to increase the water peeling force may be, for example, 2 times or more or 5 times or more relative to the water peeling force N2 measured by the above method for the adhesive sheet. It may be 10 times or more, 20 times or more, or 30 times or more. The water peeling force N3 may be, for example, 2.0 N/10 mm or more, 3.0 N/10 mm or more, or 4.0 N/10 mm or more. In addition, the water peeling force N3 was measured in the same manner as the water peeling force N2 described above, except that the evaluation sample taken out from the autoclave was treated to increase the water peeling force.

The adhesive composition used to form the A layer may contain acid or alkali (ammonia, etc.) used for the purpose of pH adjustment or the like, if necessary. Examples of other optional ingredients that may be included in the composition include viscosity adjusters (such as thickeners), leveling agents, plasticizers, fillers, colorants such as pigments or dyes, stabilizers, preservatives, and preservatives. Various additives commonly used in the field of adhesive compositions such as aging agents. As for such various additives, conventionally known ones can be used by conventional methods. Since they do not particularly characterize the present invention, detailed descriptions are omitted.

(2)B layer The adhesive layer of the adhesive sheet peeled off by the peeling method disclosed herein may further include, in addition to the A layer constituting at least the surface of the polarizing plate side of the adhesive layer, the B disposed on the back side of the A layer. layer. According to the structure including the A layer and the B layer, for example, the A layer can provide good water releasability, and the B layer can adjust the overall properties of the adhesive layer (for example, water resistance, cohesion, heat resistance, etc.). Therefore, according to the adhesive layer composed of the A layer and the B layer, it is easy to obtain an adhesive sheet with good water removability and excellent water resistance reliability. For example, an adhesive sheet with a low water-resistant adhesive force reduction rate and a high water peeling adhesive force reduction rate can be preferably realized. Furthermore, for example, it is possible to preferably realize an adhesive sheet that has both strong adhesiveness and good water releasability at a high level.

Layer B can be disposed in direct contact with the back surface of layer A, or can be disposed with other layers between it and the back surface of layer A. The above-mentioned other layer (hereinafter, also referred to as the middle layer) is typically a non-adhesive layer. For example, the same plastic film, foam sheet, woven fabric, or paper as the support described below can be used. , metal foil, etc. From the perspective of the flexibility of the adhesive sheet or its ability to follow the surface shape of the adherend, in some aspects, it is better to use layer A and layer B to be in direct contact (that is, without an intermediate layer) And the adhesive layer composed of laminates.

The B layer may be selected from the group consisting of acrylic adhesives, rubber adhesives, polysiloxane adhesives, polyester adhesives, urethane adhesives, polyether adhesives, and polyamide adhesives. The adhesive layer is composed of one or more than two kinds of well-known adhesives such as adhesives and fluorine-based adhesives. From the viewpoint of transparency or weather resistance, in some aspects, an acrylic adhesive can be preferably used as the constituent material of the B layer. The acrylic adhesive constituting the B layer can be selected from those exemplified as the acrylic adhesives that can be used for the A layer, for example, so that desired characteristics can be exerted in combination with the A layer. Layer B may be a single-layer structure including one layer, or may be a multi-layer structure including two or more layers with different compositions.

In some aspects, the monomer component constituting the polymer (for example, an acrylic polymer) contained in the B layer may contain (meth)acrylic acid C _1-20 alkane at a ratio of 40% by weight or more of the total monomer component. base ester. The proportion of C _1-20 alkyl (meth)acrylate in the total monomer component of the B layer may be, for example, 98% by weight or less. From the perspective of improving the cohesiveness of the B layer, it may also be 95% by weight. % or less, it may be 85% by weight or less, it may be 70% by weight or less, or it may be 60% by weight or less. The monomer component constituting layer B may include alkyl (meth)acrylate and copolymerizable monomers. The copolymerizable monomer can be appropriately selected from those exemplified as copolymerizable monomers that can be used for the A layer. The usage amount of the copolymerizable monomer may be, for example, 5% by weight or more, 15% by weight or more, 30% by weight or more, or 40% by weight or more of the total monomer components constituting layer B.

In certain aspects, the proportion of the carboxyl group-containing monomer in the monomer components constituting the B layer may be, for example, 2% by weight or less, 1% by weight or less, or 0.5% by weight or less. It is also possible to substantially not use a carboxyl group-containing monomer as the monomer component constituting the B layer. Here, the term "substantially not using a carboxyl group-containing monomer" means that a carboxyl group-containing monomer is not used at least intentionally. The adhesive sheet having the B layer having this composition is more likely to have higher water resistance reliability, so it is preferable.

As a preferred example of an adhesive sheet having an A layer and a B layer, the gel fraction of the B layer is higher than that of the A layer and the swelling degree of the B layer is lower than that of the A layer. Adhesive sheet with one or both adhesive layers. According to this structure, it is easy to obtain an adhesive sheet with a low water-resistant adhesive force reduction rate and a high water peeling adhesive force reduction rate.

In some aspects, layer B may be a layer formed of a photocurable adhesive composition or a solvent-based adhesive composition. According to the B layer formed from such a composition, an adhesive sheet with excellent water resistance and reliability can be easily obtained. For example, a combination of layer A formed of a water-dispersed adhesive composition and layer B formed of a photocurable adhesive composition, or layer A formed of a water-dispersed adhesive composition and a solvent-based adhesive In the combination of the B layer formed by the composition, an adhesive sheet with a low water-resistant adhesive force reduction rate and a high water peeling adhesive force reduction rate can be better realized. In some aspects, from the viewpoint of improving water resistance, it may be preferable to use a B layer that does not substantially contain a water affinity agent.

＜Support＞ The adhesive sheet peeled off by the peeling method disclosed herein may be in the form of an adhesive sheet with a support attached to a support joined to the other back side of the adhesive layer. The material of the support is not particularly limited and can be appropriately selected according to the purpose of use or usage pattern of the adhesive sheet. Non-limiting examples of supports that can be used include polyolefin films containing polyolefins such as polypropylene and ethylene-propylene copolymers as the main component, polyethylene terephthalate or polyterephthalate films. Polyester film with polyester as the main component such as butylene formate, polyvinyl chloride film with polyvinyl chloride as the main component and other plastic films; including polyurethane foam, polyethylene foam, polychloroprene foam Foam sheets of other foams; obtained by spinning various fibrous materials (which can be natural fibers such as linen and cotton, synthetic fibers such as polyester and vinylon, semi-synthetic fibers such as acetate, etc.) alone or in blends Woven and non-woven fabrics; Japanese paper, Dowling paper, kraft paper, crepe paper and other papers; aluminum foil, copper foil and other metal foils, etc. It can also be a support body composed of a composite of these. Examples of the support of such a composite structure include a support having a structure in which a metal foil and the above-mentioned plastic film are laminated, a plastic sheet reinforced with inorganic fibers such as glass cloth, and the like.

As the support, various films (hereinafter also referred to as support films) can be preferably used. The above-mentioned supporting film may be a porous film such as a foam film or a non-woven sheet, or may be a non-porous film, or may be a film having a structure in which a porous layer and a non-porous layer are laminated. In some aspects, as the above-mentioned support film, one including a resin film that can independently maintain its shape (either self-standing or independent) as a base film can be preferably used. Here, the term "resin film" means a non-porous structure, typically a resin film that does not contain substantially bubbles (no voids). Therefore, the above-mentioned resin film is a concept that is 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, polyester, polyolefin, polycyclic olefin derived from a monomer having an aliphatic ring structure such as a norvinyl structure, nylon 6, nylon 66, partially aromatic polyamide, etc. Polyamide (PA), polyimide (PI), polyamide imide (PAI), polyether ether ketone (PEEK), polyether sulfide (PES), polyphenylene sulfide (PPS), polycarbonate ester (PC), polyurethane (PU), ethylene-vinyl acetate copolymer (EVA), polystyrene, polyvinyl chloride, polyvinylidene chloride, polytetrafluoroethylene (PTFE) and other fluororesins , acrylic resins such as polymethyl methacrylate, cellulose polymers such as diacetyl cellulose or triacetyl cellulose, vinyl butyraldehyde polymers, aryl ester polymers, polyoxymethylene polymers, Resins such as epoxy polymers. The above-mentioned resin film may be formed using a resin material containing one type of resin alone, or may be formed using a blend of two or more resin materials. The above-mentioned resin film may be unstretched or stretched (eg, uniaxially stretched or biaxially stretched).

Preferable examples of the resin material constituting the resin film include polyester resin, PPS resin and polyolefin resin. Here, the polyester-based resin refers to a resin containing polyester in a ratio exceeding 50% by weight. Similarly, PPS resin refers to a resin containing PPS in a ratio exceeding 50% by weight, and polyolefin-based resin refers to a resin containing polyolefin in a ratio exceeding 50% by weight.

As the polyester-based resin, typically, a polyester-based resin containing a polyester obtained by polycondensing a dicarboxylic acid and a glycol as a main component is used. Specific examples of the polyester-based resin include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), and polynaphthalenedicarboxylic acid. Butylene glycol, etc.

As the polyolefin resin, one type of polyolefin can be used alone or two or more types of polyolefin can 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, etc. Specific examples include ethylene-propylene copolymers such as polyethylene (PE), polypropylene (PP), poly-1-butene, poly-4-methyl-1-pentene, and ethylene propylene rubber (EPR). , ethylene-propylene-butylene copolymer, ethylene-butylene copolymer, ethylene-vinyl alcohol copolymer, ethylene-ethyl acrylate copolymer, etc. Either low density (LD) polyolefin or high density (HD) polyolefin can be used. Examples of polyolefin resin films include unstretched polypropylene (CPP) film, biaxially stretched polypropylene (OPP) film, low-density polyethylene (LDPE) film, and linear low-density polyethylene (LLDPE). ) film, medium density polyethylene (MDPE) film, high density polyethylene (HDPE) film, polyethylene (PE) film blended with two or more polyethylene (PE), polypropylene (PP) and Polyethylene (PE) PP/PE blended film, etc.

Specific examples of resin films that can be preferably used as supports include PET films, PEN films, PPS films, PEEK films, CPP films, and OPP films. In terms of strength, preferred examples include PET film, PEN film, PPS film and PEEK film. From the viewpoints of ease of acquisition, dimensional stability, optical properties, etc., a PET film is a preferable example.

In the resin film, known additives such as light stabilizers, antioxidants, antistatic agents, colorants (dyes, pigments, etc.), fillers, lubricants, and anti-adhesive agents may be blended as needed. The compounding amount of the additive is not particularly limited and can be appropriately set according to the use of the adhesive sheet.

The manufacturing method of the resin film is not particularly 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 support may be substantially composed of such a resin film. Alternatively, the support may include an auxiliary layer in addition to the resin film. Examples of the above-mentioned auxiliary layer include: a printing layer or a laminated layer, an antistatic layer, and a layer for imparting a desired appearance to an optical property adjustment layer (such as a colored layer, an antireflection layer), a support, or an adhesive sheet; Surface treatment layers such as base coat and peeling layer. Moreover, the said support material may be the following optical member.

The thickness of the support is not particularly limited and can be selected according to the purpose of use or usage pattern of the adhesive sheet. The thickness of the support may be, for example, 1000 μm or less, 500 μm or less, 100 μm or less, 70 μm or less, 50 μm or less, 25 μm or less, or 10 μm or less. μm or less, and may be 5 μm or less. When the thickness of the support becomes smaller, the flexibility of the adhesive sheet and its ability to follow the surface shape of the adherend tend to increase. In addition, from the viewpoint of operability, processability, etc., the thickness of the support may be, for example, 2 μm or more, may be more than 5 μm, or may be more than 10 μm. In some aspects, the thickness of the support may be, for example, 20 μm or more, 35 μm or more, or 55 μm or more.

The side that is bonded to the adhesive layer in the support can also be subjected to corona discharge treatment, plasma treatment, ultraviolet irradiation treatment, acid treatment, alkali treatment, primer coating, and antistatic treatment if necessary. and other previously known surface treatments. This kind of surface treatment can be a treatment used to improve the adhesion between the support and the adhesive layer, in other words, the adhesive layer's grip on the support. 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, but is usually about 0.01 μm to 1 μm, preferably about 0.1 μm to 1 μm.

The surface of the support that is opposite to the side bonded to the adhesive layer (hereinafter also referred to as the back surface) may be subjected to previously known surface treatments such as peeling treatment, adhesion or adhesion improvement treatment, and antistatic treatment if necessary. . For example, by surface-treating the back surface of the support with a release treatment agent, the unwinding force of the adhesive sheet wound into a roll can be reduced. As the release treatment agent, polysiloxane-based release treatment agents, long-chain alkyl-based release treatment agents, olefin-based release treatment agents, fluorine-based release treatment agents, fatty acid amide-based release treatment agents, molybdenum sulfide, and silicon dioxide can be used. Powder etc.

＜Adhesive sheet＞ The adhesive layer constituting the adhesive sheet may be a hardened layer of the adhesive composition. That is, the adhesive layer can be formed by applying (for example, coating) the adhesive composition to an appropriate surface and then performing a hardening treatment as appropriate. When two or more hardening treatments (drying, cross-linking, polymerization, etc.) are performed, they can be performed simultaneously or through multiple stages. In an adhesive composition using a partial polymer (acrylic polymer slurry) as a monomer component, a final copolymerization reaction is typically performed as the above-mentioned hardening treatment. 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 cross-linking and drying can also be carried out as needed. For example, when it is necessary to dry the photocurable adhesive composition, photohardening can be performed after drying. In an adhesive composition using a complete polymer, typically, as the above-mentioned hardening treatment, drying (heat drying), cross-linking and other treatments are performed as 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 coated on the preformed first adhesive layer, and the adhesive composition may be hardened to form the second adhesive layer.

The adhesive composition can be coated using, for example, a gravure roll coater, a reverse roll coater, a contact roll coater, a dip roll coater, a rod coater, a blade coater, or a spray coater. Wait for the usual coating machine to be implemented. In an adhesive sheet having the form of a support, as a method of providing an adhesive layer on the support, a direct method of directly applying an adhesive composition to the support to form an adhesive layer can be used, or a method of forming an adhesive layer can be used. A transfer method in which the adhesive layer on the peeling surface is transferred to the support.

The thickness of the adhesive layer is not particularly limited, but may be about 3 μm to 1000 μm, for example. From the perspective of making the adhesive layer closely adhere to the adherend to improve water resistance reliability, in some aspects, the thickness of the adhesive layer may be, for example, 5 μm or more, 10 μm or more, or 20 μm. It may be 30 μm or more, it may be 50 μm or more, it may be more than 50 μm, it may be 70 μm or more, it may be 100 μm or more, it may be 120 μm or more. Furthermore, from the viewpoint of preventing paste residue due to cohesion and destruction of the adhesive layer, in some aspects, the thickness of the adhesive layer may be, for example, 500 μm or less, 300 μm or less, or 200 μm. μm or less, and may be 170 μm or less. The technology disclosed in this article can also be preferably applied to adhesive sheets with an adhesive layer thickness of less than 130 μm, less than 90 μm, less than 60 μm, or less than 40 μm. Furthermore, in the adhesive layer composed of the A layer, the thickness of the adhesive layer means the thickness of the A layer.

When the adhesive layer becomes thicker, it tends to be difficult to achieve both water-removability and water-resistant reliability in general. From this point of view, when the thickness of the adhesive layer exceeds 50 μm, for example, the adhesive layer may preferably be composed of layer A and layer B. According to the adhesive layer having this structure, even if the adhesive layer becomes thick, it is easy to obtain an adhesive sheet that has both water-removability and water-resistant reliability at a high level.

In the case where the adhesive layer includes layer A and layer B, the thickness of layer A may be, for example, 1 μm or more, 2 μm or more, 4 μm or more, 5 μm or more, or 5 μm or more. 10 μm or more, or 15 μm or more. Moreover, the thickness of the A layer may be, for example, 50 μm or less, 45 μm or less, 35 μm or less, or 25 μm or less. In particular, in the case where the A layer is formed of a water-dispersible adhesive component or the A layer contains a water affinity agent, if the thickness of the A layer is not too large, the water resistance reliability of the adhesive sheet will be improved and the adhesion will be improved. It is preferable from the viewpoint of improving the transparency of the agent layer.

In the case where the adhesive layer includes layer A and layer B, the thickness of layer B can be, for example, 5 μm or more, or 10 μm or more. From the viewpoint of better exerting the effect of providing the B layer on the back side of the A layer, in some aspects, the thickness of the B layer may be, for example, 20 μm or more, or 30 μm or more, or It may be 50 μm or more, 70 μm or more, or 100 μm or more.

In the case where the adhesive layer includes layer A and layer B, the thickness of layer A accounting for the entire thickness of the adhesive layer may be, for example, 90% or less, usually preferably 70% or less, and may also be 50%. It can be less than 30%, 20% or less, or 15% or less. Furthermore, from the viewpoint of the ease of formation of the A layer or the water releasability of the adhesive sheet, in some aspects, the thickness of the A layer in the entire thickness of the adhesive layer may be, for example, 3% or more. It may be more than 5%, more than 7%, or more than 10%.

＜Peel-off method＞ According to this specification, a method for peeling off an adhesive sheet attached to a polarizing plate as an adherend is provided. The peeling method includes a water peeling step, which is to make the aqueous liquid follow the state where an aqueous liquid exists at the interface between the adherend and the adhesive sheet at the peeling line of the adhesive sheet from the adherend. As the peeling front line moves to the interface, the adhesive sheet is peeled off from the adherend. According to the water peeling step, the aqueous liquid can be effectively used to peel the adhesive sheet from the polarizing plate as the adherend. As an aqueous liquid, water or a mixed solvent containing water as the main component and optionally a small amount of additives can be used. As a solvent other than water constituting the above mixed solvent, lower alcohol (for example, ethanol) or lower ketone (for example, acetone) that can be uniformly mixed with water can be used. As the above-mentioned additives, known surfactants and the like can be used. From the viewpoint of avoiding contamination of the adherend, in some aspects, it is preferable to use an aqueous liquid that does not substantially contain additives. From an environmental hygiene point of view, it is particularly preferred to use water as the aqueous liquid. The water is not particularly limited. For example, distilled water, ion-exchanged water, tap water, etc. can be used, taking into consideration the purity required according to the use, ease of acquisition, etc.

In some aspects, the above-mentioned peeling method can be preferably carried out in the following aspect, that is, in the same manner as in the measurement of the water peeling force N2, the adherend near the outer edge of the adhesive sheet attached to the adherend is The aqueous liquid is supplied onto the body so that the aqueous liquid enters from the outer edge of the adhesive sheet to the interface between the adhesive sheet and the adherend, and no new water is supplied (that is, it is only used to supply water before peeling off). to the aqueous liquid on the adherend) to peel off the adhesive sheet. Furthermore, if the water that follows the movement of the peeling front line and enters the interface between the adhesive sheet and the adherend is exhausted in the middle of the water peeling step, it is also possible to intermittently start the water peeling step. Or supply water continuously. For example, when the adherend is water-absorbent, or when an aqueous liquid is likely to remain on the surface of the adherend or the adhesive surface after peeling off, it may be preferable to additionally supply water after the start of the water-stripping step. .

The amount of aqueous liquid supplied before peeling is started is not particularly limited as long as it is an amount that can introduce the aqueous liquid from outside the attachment range of the adhesive sheet to the interface between the adhesive sheet and the adherend. The amount of the aqueous liquid may be, for example, 5 μl or more, usually 10 μl or more, or 20 μl or more. In addition, there is no particular restriction on the upper limit of the amount of the aqueous liquid. In some aspects, from the viewpoint of improving workability, the amount of the aqueous liquid may be, for example, 10 ml or less, 5 ml or less, 1 ml or less, 0.5 ml or less, or It is 0.1 ml or less, or it can be 0.05 ml or less. By reducing the amount of the aqueous liquid, the operation of removing the aqueous liquid by drying or wiping after peeling off the adhesive sheet can be omitted or simplified.

At the beginning of peeling, the operation of causing the aqueous liquid to enter from the outer edge of the adhesive sheet to the interface between the adhesive sheet and the adherend can be performed, for example, as follows: inserting a cut at the outer edge of the adhesive sheet at the interface Using the tip of a jig such as a knife or needle, use a hook or fingernail to scratch the outer edge of the adhesive sheet and lift it up, so that a strong adhesive tape or suction cup can be attached to the back surface near the outer edge of the adhesive sheet to lift up the adhesive sheet. The end of the sheet etc. By forcing the aqueous liquid from the outer edge of the adhesive sheet to the interface, a state in which the aqueous liquid exists at the interface between the adherend and the adhesive sheet can be efficiently formed. Furthermore, it is possible to achieve a better balance between good water-removability after the operation of forcibly entering the aqueous liquid into the interface to form a starting point of peeling, and high water-resistant reliability when this operation is not performed.

The adhesive sheet peeled off by the above-mentioned peeling method preferably includes an adhesive layer, and in the above-mentioned adhesive layer, at least the A layer constituting the surface on the polarizing plate side is composed of an adhesive containing a water affinity agent. The above-mentioned adhesive sheet is preferably any adhesive sheet disclosed herein. Therefore, the above peeling method is suitable as a peeling method for any adhesive sheet disclosed herein.

Some aspects of the water peeling step can be preferably implemented in an aspect in which the above-mentioned peeling front line is moved at a speed of 10 mm/min or more. Moving the peeling front line at a speed of 10 mm/min or more is equivalent to peeling the adhesive sheet at a stretching speed of 20 mm/min or more at a peeling angle of 180 degrees. The speed at which the peeling front line is moved may be, for example, 50 mm/min or more, 150 mm/min or more, 300 mm/min or more, or 500 mm/min or more. According to the peeling method disclosed in this article, by allowing the aqueous liquid to enter the interface while peeling the adhesive sheet from the adherend, good water can be exerted even at such a relatively fast peeling speed. Peelability. There is no particular limit on the speed at which the stripping front can move. The speed at which the peeling front line is moved can be, for example, 1000 mm/min or less.

The peeling method disclosed herein can be such that the peeling area of the adhesive sheet per 10 μl of the aqueous liquid (such as water) used in the method is, for example, 50 cm ² or more, preferably 100 cm ² or more. implemented in. [Example]

Below, several embodiments related to the present invention are described, but the present invention is not intended to be limited to those shown in the embodiments. Furthermore, in the following description, unless otherwise stated, "parts" and "%" are based on weight.

＜Example 1＞ (Preparation of adhesive composition U-1) It will contain 2-ethylhexyl acrylate (2EHA), N-vinyl-2-pyrrolidone (NVP), 2-hydroxyethyl acrylate (HEA) and isoacrylate in a weight ratio of 80/35/5/30. 100 parts of the monomer mixture of IBXA, and 0.05 parts of the trade name: Irgacure 651 (manufactured by Ciba Specialty Chemicals Co., Ltd.) as a photopolymerization initiator and the trade name: Irgacure 184 (manufactured by Ciba Specialty Chemicals Co., Ltd.) 0.05 parts were put into a four-necked flask together, and photopolymerized by irradiating ultraviolet rays under a nitrogen atmosphere until the viscosity (BH viscometer, No. 5 spindle, 10 rpm, measurement temperature 30°C) became about 15 Pa·s, to prepare A monomer slurry containing part of the polymer of the above monomer mixture. To 100 parts of the monomer slurry, add 0.13 parts of 1,6-hexanediol diacrylate (HDDA) and 0.33 parts of photopolymerization initiator (trade name: Irgacure 651, manufactured by Ciba Refining Chemicals Co., Ltd.), and mix evenly Mix thoroughly to prepare ultraviolet curable adhesive composition U-1.

(Preparation of adhesive composition E-1) 85 parts of 2EHA, 13 parts of methyl acrylate (MA), 1.2 parts of AA, 0.8 parts of MAA, 0.02 parts of 3-methacryloxypropyltrimethoxysilane (KBM-503, manufactured by Shin-Etsu Chemical Industry Co., Ltd.), A monomer mixture was prepared by mixing and emulsifying 0.048 parts of tertiary dodecylmercaptan as a chain transfer agent and 2.0 parts of an emulsifier (Latemul E-118B manufactured by Kao Corporation) in 100 parts of ion-exchange water. Aqueous emulsion (monomer emulsion). The above-mentioned monomer emulsion was added to a reaction vessel equipped with a cooling tube, a nitrogen gas introduction tube, a thermometer and a stirring device, and the mixture was stirred at room temperature for more than 1 hour while introducing nitrogen gas. Then, the system was heated to 60° C., and 2,2'-azobis[N-(2-carboxyethyl)-2-methylpropionamidine] hydrate (Wako Pure Chemical Industries, Ltd.) was added as a polymerization initiator. (manufactured by VA-057) 0.1 part, reacted at 60°C for 6 hours, and obtained an aqueous dispersion of acrylic polymer. After the system is cooled to normal temperature, 30 parts of adhesion-imparting resin emulsion (Super Ester E-865NT manufactured by Arakawa Chemical Co., Ltd. manufactured by Arakawa Chemical Co., Ltd., softened) is added to every 100 parts of the solid content of the aqueous dispersion of the acrylic polymer, based on the solid content. aqueous dispersion of polymerized rosin ester at 160°C). Furthermore, 10% ammonia as a pH adjuster and polyacrylic acid (36% non-volatile aqueous solution) as a tackifier were used to adjust the pH to about 7.5 and the viscosity to about 9 Pa·s to prepare an emulsion-type adhesive. Agent composition E-1.

(Production of adhesive sheets) Adhesive composition U-1 was applied to a 38 μm-thick release film R1 (Mitsubishi Plastics Co., Ltd., MRF#38) that became the peeling surface on one side of the polyester film, and the one side of the polyester film became the peeling surface. The release film R2 (Mitsubishi Plastics Co., Ltd., MRE#38) with a thickness of 38 μm blocks the air and is irradiated with ultraviolet rays to harden it, thereby forming an adhesive layer B1 with a thickness of 130 μm. Then, the release film R2 covering the adhesive layer B1 is peeled off and laminated to a corona-treated polyethylene terephthalate (PET) film with a thickness of 75 μm, thereby obtaining a PET film (support) and an adhesive. A laminated sheet in which layer B1 and release film R1 are laminated in this order. The adhesive composition E-1 was applied to the release film R1 (Mitsubishi Plastics Co., Ltd., MRF#38) and dried at 120°C for 3 minutes to form an adhesive layer A1 with a thickness of 20 μm. The release film R1 covering the adhesive layer B1 of the above-mentioned laminated sheet is peeled off, and the adhesive layer A1 is bonded here, thereby obtaining an adhesive having a two-layer structure in which the adhesive layer B1 and the adhesive layer A1 are in direct contact and laminated. layer, and an adhesive sheet S1 composed of a PET film (support) bonded to the surface of the B1 layer side of the adhesive layer. The surface of the adhesive sheet on the A1 layer side is protected by the release film R1 for forming the adhesive layer A1.

(Preparation of adherend) A solution (manufactured by DIC Co., Ltd., trade name " UNIDIC 17-806", solid content concentration 80%), add 5 parts of photopolymerization initiator (manufactured by Ciba Japan Co., Ltd., product name "IRGACURE906") per 100 parts of the solid content of the solution, Leveling agent (manufactured by DIC Co., Ltd., product name "GRANDIC PC4100") 0.03 parts. Thereafter, butyl acetate was added to the above solution to adjust the solid content concentration to 75%, and cyclopentanone (hereinafter, referred to as "CPN") was further added to adjust the solid content concentration to 50%. In this way, a hard coat layer forming material for forming a hard coat layer is produced. When the total amount of the hard-coat-forming material is 1, the content ratio (mass ratio) of the good solvent (CPN) in the hard-coat-forming material is 0.33. The ultraviolet curable resin monomer or oligomer contained in the hard coat forming material is a mixture of urethane acrylates of various molecular weights, and the total amount of the ultraviolet curable resin monomer or oligomer is When it is set to 1, the content ratio (mass ratio) of low molecular weight components (here refers to ultraviolet curable resin monomers or oligomers with a molecular weight of 800 or less) is 0.482. The above-mentioned hard-coat layer forming material was coated on a transparent TAC film (manufactured by Fuji Film Co., Ltd., product name "TD80UL", thickness 80 μm, refractive index 1.49) using a die nozzle coater to form a coating film. The coating thickness of the hard coat forming material was set to 13.8 μm. That is, the hard coat layer forming material was applied so that the thickness of the cured coating film (hard coat layer) became 7.5 μm, assuming that the solvent did not penetrate into the film. The above coating film was dried at 80° C. for 2 minutes. Thereafter, the above-mentioned coating film was irradiated with ultraviolet rays with a cumulative light intensity of 300 mJ/cm ² using a high-pressure mercury lamp to polymerize the resin monomer. In this way, a hard coating layer is formed on the TAC film. The hard coat layer has an intrinsic refractive index of 1.53. Then, the antireflection layer forming material shown below is evenly coated on the entire surface of the hard coat layer using a die nozzle coater. The coating film was heated at 90° C. for 2 minutes and irradiated with ultraviolet rays to harden it, thereby forming an antireflection layer with a thickness of 0.1 μm on the entire surface of the hard coat layer. The refractive index of the anti-reflective layer is 1.38. The material for forming the above-mentioned anti-reflective layer is a low-refractive material (manufactured by JSR Co., Ltd., trade name "JUA204". Solid content concentration: 9.5%), to which methyl isobutyl ketone (MIBK) and tertiary butanol ( TBA) mixed solvent (MIBK: TBA = 50:50), and adjust to a solid content concentration of 2.0%. The low-refractive material includes a fluorine compound having an ethylenically unsaturated group, an acrylate, a polymerization initiator, and an ultraviolet curable resin containing approximately 50% hollow nanosilica based on the active ingredient. In this way, a TAC film F1 having a surface on which a hard coat layer and an anti-reflection layer are sequentially laminated is obtained. The surface (adhered surface) of the TAC film F1 that was corona treated under the above conditions was set as the adherend in Example 1.

(Performance evaluation) Using the above-mentioned adherend, measure the normal adhesion force N0, water-resistant adhesion force N1 and water peeling force N2 of the A-layer side of the adhesive sheet S1 by the above-mentioned method. The time from corona treatment of the adhered surface to attachment of the adhesive sheet S1 is set to within 30 minutes. Based on the measured values obtained, the water-resistant adhesive force reduction rate and the water peeling adhesive force reduction rate were calculated. The results are shown in Table 1.

＜Example 2＞ In this example, as the adherend, the above-mentioned TAC film F1 was used without corona treatment on its surface (adhered surface). In other respects, it is the same as Example 1. The normal adhesion force N0, water-resistant adhesion force N1 and water-peel strength N2 of the A-layer side of the adhesive sheet S1 are measured, and the water-resistant adhesion force reduction rate and the water-peel adhesion force reduction rate are calculated. The results are shown in Table 1.

[Table 1]

As shown in Table 1, in Example 1 using a corona-treated adherend, for the adhesive sheet S1 with a low water-resistant adhesion reduction rate, a small amount of water can be used to easily remove the adhesive sheet S1 from the adherend. Ground peeling. On the other hand, in Example 2 in which an adherend without corona treatment was used, the adhesive sheet S1 had a low water peeling adhesive force reduction rate and was difficult to peel off with water.

Specific examples of the present invention have been described in detail above, but these are only examples and do not limit the scope of the patent application. The technology described in the scope of the patent application includes various changes and modifications of the specific examples illustrated above.

1. 2‧‧‧Adhesive sheet 10‧‧‧Adhesive layer (A layer) 10A‧‧‧One surface (adhesive surface, polarizing plate side surface) 10B‧‧‧Another surface 20‧‧‧Support 20A‧‧‧Side 1 20B‧‧‧Second side (back) 30‧‧‧Release liner 50‧‧‧Adhesive sheet with release liner 70‧‧‧Component (polarizing plate) 110‧‧‧Adhesive layer 110A‧‧‧One surface (adhesive surface, polarizing plate side surface) 112‧‧‧A Floor 114‧‧‧B Floor 200‧‧‧Components with adhesive sheets

FIG. 1 is a cross-sectional view schematically showing the structure of an adhesive sheet. FIG. 2 is a cross-sectional view schematically showing the structure of another adhesive sheet. FIG. 3 is a cross-sectional view schematically showing an adhesive sheet-attached member in which another adhesive sheet is attached to the member.

1‧‧‧Adhesive sheet

10‧‧‧Adhesive layer (A layer)

10A‧‧‧One surface (adhesive surface, polarizing plate side surface)

10B‧‧‧Another surface

20‧‧‧Support

20A‧‧‧Side 1

20B‧‧‧Second side (back)

30‧‧‧Release liner

50‧‧‧Adhesive sheet with release liner

Claims (3)

An adhesive sheet peeling method, which is a method of peeling off an adhesive sheet attached to a polarizing plate, and the adhesive sheet has an adhesive layer, and the adhesive layer includes at least the surface of the polarizing plate side that constitutes the adhesive layer The A layer of the above-mentioned A layer contains a water affinity agent, and the surface of the side of the above-mentioned polarizing plate on which the above-mentioned adhesive sheet is attached is subjected to corona treatment or plasma treatment. The above-mentioned adhesive sheet stripping method includes a water stripping step, which is based on When the peeling line of the adhesive sheet from the polarizing plate is in a state where an aqueous liquid exists at the interface between the polarizing plate and the adhesive sheet, the aqueous liquid follows the movement of the peeling line and enters the interface. The adhesive sheet is peeled off from the polarizing plate. The adhesive sheet peeling method of claim 1, wherein in the water peeling step, the peeling front line is moved at a speed of 10 mm/min or more. For example, the adhesive sheet peeling method of claim 1 or 2, wherein the above-mentioned layer A is water-insoluble and non-water-swellable. Non-water-soluble means that the gel fraction measured by the following method is more than 75% and non-water-swellable. It means that the swelling degree measured by the following method is less than 2: Weigh about 0.5g of the adhesive to be measured, set its weight as W1, immerse the adhesive in 500ml of distilled water at room temperature for 48 hours, and then use nylon Filter through a sieve, measure the weight W2 of the adhesive containing water, and then dry the adhesive at 130°C for 5 hours. The weight of volatile matter W3, gel fraction and swelling degree are calculated by the following formulas: gel fraction [%] = (W3/W1) × 100 and swelling degree = W2/W1.