JP2022169268A - surface protection film - Google Patents

Abstract

[Problem] To provide a surface protection film that can be handled using existing equipment and is easy to peel off. [Solution] A base material layer and an adhesive layer provided on one side of the base material layer are provided, the adhesive force of the adhesive layer to the acrylic plate is 0.01 to 0.09 N/25 mm, and the film is A surface protection film with a thickness of 30 to 60 μm is used. [Selection diagram] Figure 1

Description

TECHNICAL FIELD The present invention relates to a surface protection film provided with an adhesive layer. More specifically, it relates to a surface protection film that can be easily peeled off using existing equipment.

Surface protective films are used for electronic devices because if they are scratched during the manufacturing process, or if dirt or dust adheres to them, the devices will be defective or the quality of the products will be degraded. The surface protection film is removed during the assembly process as it is not needed in the final product. These manufacturing processes are automated, and peeling of the surface protective film is also performed automatically. Methods of automatic peeling include a method of winding the film into a roll, a method of peeling the surface protective film by pulling a peeling tape attached to the surface protective film, and the like.

In the latter method, the release tape may be separated from the surface protective film during separation. Therefore, in order to ensure and facilitate the peeling of the surface protective film, a method of changing the outer shape of the adhesive portion of the peeling tape (see, for example, Patent Document 1), or a peeling member provided with an inclination with respect to the peeling direction. A method of peeling while moving relative to each other has been proposed (see Patent Document 2, for example).

JP 2014-59378 A JP 2012-148824 A

Changing existing release tapes and machinery is labor intensive. Therefore, it is desired to develop a surface protective film that can be easily peeled off with existing equipment.

As a result of intensive studies, the inventors of the present invention have found that, in a surface protection film comprising a substrate layer and an adhesive layer provided on one side of the substrate layer, the adhesion of the adhesive layer to an acrylic plate is 0.5. 01 to 0.09 N/25 mm and a film thickness of 30 to 60 μm, the surface protective film is found to be easily peeled off, leading to the completion of the present invention. That is, the gist of the present invention is as follows.

[1] A base material layer and an adhesive layer provided on one surface of the base material layer, and the adhesive strength of the adhesive layer to an acrylic plate is 0.01 to 0.09 N/25 mm or less. , a surface protective film having a film thickness of 30 to 60 μm.
[2] The surface protective film of [1], which has a tensile modulus of 100 to 1000 MPa.
[3] The surface protection film according to [1] or [2], wherein the base layer has a thickness of 20 to 40 μm.
[4] The surface protective film according to any one of [1] to [3], wherein the pressure-sensitive adhesive layer has a thickness of 5 to 20 µm.
[5] The surface protection film according to any one of [1] to [4], wherein the substrate layer contains at least one of polyolefin resin and polyester resin.
[6] The surface protection film of [5], wherein the polyolefin resin is at least one selected from the group consisting of low-density polyethylene, medium-density polyethylene, high-density polyethylene, and polypropylene.
[7] The surface protective film according to any one of [1] to [6], wherein the pressure-sensitive adhesive layer is at least one selected from the group consisting of polyolefin resins, EVA resins, and acrylic resins. .
[8] The surface protection film of [7], wherein the pressure-sensitive adhesive layer is at least one selected from the group consisting of low-density polyethylene, linear low-density polyethylene, and EVA resin.
[9] The surface protective film according to any one of [1] to [8], which has a peel strength to an acrylic plate of 0.1 to 0.5 N/50 mm.
[10] The surface protection film according to any one of [1] to [9], which is in roll form.

The surface protection film of the present invention can be used with existing equipment, and has the effect of being easy to peel off.

FIG. 1 is a schematic cross-sectional view showing one embodiment of the surface protective film of the present invention.

An example of a preferred mode for carrying out the present invention will be described below. However, the following embodiments are examples for explaining the present invention, and the present invention is not limited to the following embodiments.

[Surface protection film]
The surface protective film of the present invention comprises a substrate layer and an adhesive layer provided on one surface of the substrate layer. One embodiment of the surface protection film will be described with reference to FIG. As shown in FIG. 1 , the surface protective film 10 includes a substrate layer 1 and an adhesive layer 2 provided on one surface of the substrate layer 1 . When applying the surface protective film 10 to protect the surface of an adherend (not shown) such as an electronic device, the surface protective film 10 is adhered so that the pressure-sensitive adhesive layer 2 adheres to the surface of the electronic device. be done.

The thickness of the surface protective film is 30-60 μm, preferably 30-50 μm. When the surface protective film has a thickness of 30 to 60 μm, the surface protective film is easily peeled off from adherends such as electronic devices. Moreover, the strength required for the surface protection film can be easily obtained. Furthermore, when the surface protective film is wound into a roll, the occurrence of folds and wrinkles can be reduced.
“The surface protective film is easily peeled off from the adherend” means that when the surface protective film is peeled off from the adherend such as an electronic device using a release tape, the problem of peeling of the release tape is unlikely to occur.

The peel strength of the surface protection film to the acrylic plate is preferably 0.1 to 0.5 N/50 mm. When the peel strength of the surface protective film to the acrylic plate is 0.1 N/50 mm or more, unintentional peeling of the surface protective film from an adherend such as an electronic device can be reduced. When the peel strength of the surface protective film to the acrylic plate is 0.5 N/50 mm or less, the surface protective film is easily peeled off from adherends such as electronic devices.
Here, the peel strength to the acrylic plate is a value measured by the following measuring method. The surface protection film is cut into a size of 50 mm width×60 mm length, and pasted on an acrylic plate using a 2 kg roller to obtain a test piece. The test piece is allowed to stand overnight under the conditions of 23° C. and 65% relative humidity. Thereafter, a release tape (Nitto Denko No. 31B polyester adhesive tape) is attached to the surface protective film. It is peeled off with a tensile tester under the conditions of a peeling speed of 300 mm/min and a peeling angle of 180°, and the strength at the moment when the surface protective film is peeled off is defined as the peel strength.

The tensile modulus of the surface protection film is preferably 100-1000 MPa, more preferably 100-800 MPa, and even more preferably 250-800 MPa. When the tensile modulus is 100 MPa or more, breakage of the surface protective film can be reduced when the surface protective film is peeled off from an adherend such as an electronic device. When the tensile modulus is 100 to 800 MPa, it is possible to reduce the occurrence of folds and wrinkles when winding the surface protection film into a roll.
Here, the tensile elastic modulus of the surface protective film is a value measured according to JIS K7127. More specifically, the tensile modulus is a value measured by the following measuring method. A masking film cut into a width of 15 mm and a length of 100 mm is set in an apparatus with a chuck distance of 50 mm. A tensile test is performed at a tensile speed of 300 mm/min at 23° C. and a relative humidity of 65% to obtain a load-elongation curve. The tensile modulus is obtained from the tangent to the rising portion of the load-elongation curve (at 3% elongation).
Each layer constituting the surface protection film will be described below.

(Base material layer)
The base material layer has a function of protecting an adherend such as an electronic device from being scratched or being adhered with dirt, dust, or the like. A thermoplastic resin is preferable for the base material layer. Examples of thermoplastic resins include polyester-based resins, polyamide-based resins, polyolefin-based resins, polyimide-based resins, polyvinyl chloride-based resins, acrylic-based resins, and polyurethane-based resins. Among these, the thermoplastic resin preferably contains at least one of a polyolefin resin and a polyester resin, and more preferably contains a polyolefin resin, since it is easy to process, low density polyethylene, medium density polyethylene, More preferably, it is at least one selected from the group consisting of high-density polyethylene and polypropylene. Commercially available thermoplastic resins may be used. Examples of commercially available products include medium density polyethylene (trade name “T401AL” manufactured by Asahi Kasei), low density polyethylene (trade name “LF580” manufactured by Nippon Polyethylene), and polypropylene (trade name “F107A” manufactured by Prime Polymer). be done.
The thermoplastic resin may be used singly or in combination of two or more.

Various additives such as an antioxidant, an ultraviolet absorber, an antistatic agent, a plasticizer, and a colorant (pigment, dye, etc.) may be added to the thermoplastic resin. These additives are mixed with a thermoplastic resin and extruded when the base material layer is produced, or by extruding a master batch in which the additives are kneaded into the thermoplastic resin in advance. can be blended into

The thickness of the substrate layer may be in the range of 30 to 60 μm in thickness of the surface protective film. The thickness of the substrate layer is preferably 10 to 55 μm, more preferably 20 to 50 μm, even more preferably 20 to 40 μm. When the thickness of the substrate layer is 10 μm or more, the function of the surface protection film to protect the adherend can be ensured. When the thickness of the substrate layer is 55 µm or less, the surface protection film is easily peeled off from an adherend such as an electronic device.

(Adhesive layer)
The pressure-sensitive adhesive layer is provided on one surface of the substrate layer and plays a role of adhering the surface protection film to an adherend such as an electronic device. The adhesive layer has an adhesive force of 0.01 to 0.09 N/25 mm to the acrylic plate. When the adhesive strength to the acrylic plate is 0.01 to 0.09 N/25 mm, the surface protective film is easily peeled off from adherends such as electronic devices. In addition, the adhesion between the surface protective film and an adherend such as an electronic device can be ensured, and unintentional peeling of the surface protective film can be reduced.

The adhesive strength of the adhesive layer to the acrylic plate is 0.01 to 0.09 N/25 mm, preferably 0.02 to 0.05 N/25 mm. When the adhesive force to the acrylic plate is 0.01 N / 25 mm or more, the surface protective film can ensure adhesion to adherends such as electronic devices, and the surface protective film is less likely to be unintentionally peeled off. can. When the adhesive strength to the acrylic plate is 0.09 N/25 mm or less, the surface protective film is easily peeled off from adherends such as electronic devices.
Here, the adhesive strength to the acrylic plate is a value measured by the following measuring method with reference to JIS Z0237. The surface protective film is cut into a size of 25 mm wide by 200 mm long, and pasted on an acrylic plate using a 2 kg roller to obtain a test piece. The test piece is allowed to stand overnight under the conditions of 23° C. and 65% relative humidity. After that, it is peeled off with a tensile tester under the conditions of a peeling speed of 300 mm/min and a peeling angle of 180°, and the peel strength obtained is defined as adhesive strength.

The pressure-sensitive adhesive layer contains a resin component as a main component, and may contain a tackifier, a softener, and the like, if necessary. Adhesive strength and tensile elastic modulus of the pressure-sensitive adhesive layer can be adjusted by appropriately adjusting the type and blending amount of each of these components. Each component constituting the pressure-sensitive adhesive layer will be described in more detail below.

Examples of the resin component of the adhesive layer include acrylic resins, styrene resins, silicone resins, polyolefin resins, EVA resins, and acrylic resins. Among these, since it is easy to process, the resin component is preferably at least one selected from the group consisting of polyolefin resins, EVA resins, and acrylic resins, low-density polyethylene, linear low-density polyethylene, and EVA. It is more preferably at least one selected from the group consisting of system resins. A commercially available product may be used as the resin component. Examples of commercially available products include polyethylene (trade name “KS560T” manufactured by Japan Polyethylene).
The resin component may be used singly or in combination of two or more.

The tackifier, which is an optional component of the pressure-sensitive adhesive layer, has a function of improving the adhesiveness of the pressure-sensitive adhesive layer. By containing a tackifier, it is possible to moderately increase the adhesive force while suppressing the occurrence of adhesive deposits due to a decrease in the cohesive force. However, since the tackifier tends to increase the tensile modulus of the adhesive layer, it is necessary to add the tackifier to the resin component so that the tensile modulus of the adhesive layer is within the above range.
Examples of the tackifier include known tackifiers such as rosin-based resins, terpene-based resins, aliphatic petroleum-based resins, alicyclic petroleum-based resins, and aromatic resins. These tackifiers may be used singly or in combination of two or more.

The amount of the tackifier is preferably 1 to 50 parts by mass, more preferably 1 to 30 parts by mass, and further preferably 1 to 20 parts by mass, relative to 100 parts by mass of the resin component. preferable.

The softening agent, which is an optional component of the pressure-sensitive adhesive layer, can be used in combination with the above-described tackifier to adjust the pressure-sensitive adhesive strength of the pressure-sensitive adhesive layer.
Examples of softening agents include low-molecular-weight rubber-based materials, process oil (paraffin-based oil), petroleum-based softening agents, and epoxy-based compounds. These softeners may be used singly or in combination of two or more.

The amount of the softening agent to be blended is preferably 1 to 25 parts by mass, more preferably 5 to 25 parts by mass, and even more preferably 5 to 15 parts by mass with respect to 100 parts by mass of the resin component. .

The pressure-sensitive adhesive layer may contain additives such as UV inhibitors, antioxidants, fillers, and lubricants, if necessary, in addition to the components described above.

When preparing the pressure-sensitive adhesive layer, the resin component and components other than the above resin components (hereinafter also referred to as "other components") are mixed and extruded, or the other components are kneaded into the resin component in advance. By extruding the masterbatch, it can be blended with the resin component.

The thickness of the pressure-sensitive adhesive layer may be within a range in which the thickness of the surface protective film is 30 to 60 μm. The thickness of the pressure-sensitive adhesive layer is preferably 5-20 μm, more preferably 7-18 μm, even more preferably 9-15 μm. When the thickness of the pressure-sensitive adhesive layer is 5 µm or more, it is possible to secure the adhesion to an adherend such as an electronic device. When the thickness of the pressure-sensitive adhesive layer is 15 μm or less, the surface protection film can be easily peeled off from an adherend such as an electronic device.

[Method for producing surface protective film]
Next, an example of a method for producing a surface protective film will be described. First, a component constituting the adhesive layer (hereinafter also referred to as "adhesive layer component") and a component constituting the base layer (hereinafter also referred to as "base layer component") are separately placed in an extruder. supply. Specifically, the pressure-sensitive adhesive layer components are supplied to an extruder for producing the pressure-sensitive adhesive layer, the base layer components are supplied to the extruder for producing the base layer, and two extruders It is integrally formed by a two-layer coextrusion method in which each material is coextruded from one die. By adopting such a manufacturing method, a surface protection film 10 having a substrate layer 1 and an adhesive layer 2 provided on one surface of the substrate layer 1 as shown in FIG. 1 is obtained. be done.
The base material layer component may be supplied to the extruder by mixing the thermoplastic resin and the additive, or may be supplied to the extruder as a masterbatch in which the additive is kneaded into the thermoplastic resin in advance. Moreover, the pressure-sensitive adhesive layer component may be prepared by mixing the resin component and other components and extruding the mixture, or by supplying a masterbatch in which the other components are kneaded into the resin component in advance to the extruder.

In addition to the two-layer co-extrusion method, the pressure-sensitive adhesive layer may be formed on one surface of the long film forming the base layer by an extrusion molding method. Alternatively, the surface protective film may be produced by laminating the film constituting the substrate layer and the pressure-sensitive adhesive layer (film) produced as described above. From the viewpoint of facilitating control of the film thickness of the surface protective film, the surface protective film is preferably formed integrally by a two-layer coextrusion method.

The film thickness of the surface protection film is 30 to 60 μm. Therefore, the thickness of the substrate layer in the surface protective film can be, for example, 5 to 55 μm. The thickness of the adhesive layer in the surface protective film can be, for example, 5 to 15 μm.

The resulting surface protective film is usually wound into a roll for convenience of use. When the surface protection film is stored in a roll, the pressure-sensitive adhesive layer on the inner layer side adheres to the substrate layer on the outer layer side, and the surface protection film may become difficult to roll out from the roll. Therefore, although not shown, the surface protection film may have a release layer on the side opposite to the side on which the pressure-sensitive adhesive layer is provided.

The release layer may be made of any material having releasability, and examples thereof include silicone resins, organic resin-modified silicone resins, fluororesins, aminoalkyd resins, melamine resins, acrylic resins, and polyester resins. In addition, a release aid may be added to the pressure-sensitive adhesive layer in order to improve releasability. Examples of release aids include silicone-based release aids, paraffin-based release aids, polyethylene wax, and acrylic polymers.

EXAMPLES Next, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples. The methods for measuring various physical properties are the methods described above unless otherwise specified.

[Peel strength to acrylic plate (N/50 mm)]: A surface protective film was cut into a size of 50 mm wide x 60 mm long, and adhered to an acrylic plate using a 2 kg roller to obtain a test piece. The obtained test piece was allowed to stand overnight under conditions of 23° C. and 65% relative humidity. After that, a release tape was attached to the surface protective film. It was peeled off with a tensile tester at a peeling speed of 300 mm/min and a peeling angle of 180°, and the strength at the moment when the surface protective film was peeled off was taken as the peel strength. When the peel strength was 0.5 N/50 mm or less, it was determined as "◯", and when the peel strength was over 0.5 N/50 mm, it was determined as "x".

[Adhesive strength to acrylic plate (N/25 mm)]: A surface protection film was cut into a size of 25 mm wide x 200 mm long and adhered to an acrylic plate using a 2 kg roller to obtain a test piece. The obtained test piece was allowed to stand overnight under conditions of 23° C. and 65% relative humidity. After that, it was peeled off with a tensile tester under the conditions of a peel speed of 300 mm/min and a peel angle of 180°, and the obtained peel strength was taken as the adhesive strength.

[Tensile modulus (MPa)]: A masking film cut into a width of 15 mm and a length of 100 mm was set in an apparatus with a chuck distance of 50 mm. A tensile test was performed under conditions of a tensile speed of 300 mm/min, 23° C. and a relative humidity of 65% to obtain a load-elongation curve. The tensile modulus was obtained from the tangent line of the rising portion (at 3% elongation) of the obtained load-elongation curve.

(Example 1)
Medium-density polyethylene (Asahi Kasei, T401AL) was used as the base material layer component, and polyethylene (Japan Polyethylene, KS560T) was used as the pressure-sensitive adhesive layer component. A surface protective film having a base layer thickness of 20 μm, an adhesive layer thickness of 10 μm, and a film thickness of 30 μm was obtained by the T-die method with the die temperature set at 200°C. The above measurement test was performed on the obtained surface protective film. Table 1 shows the measurement results.

(Examples 2-4, Comparative Examples 1-3)
A surface protective film was obtained in the same manner as in Example 1, except for the changes shown in Table 1. The above measurement test was performed on the obtained surface protective film. Table 1 shows the measurement results.
Details of each component in Table 1 are as follows.
(Base material layer)
・Medium density ethylene: product name “T401AL”, manufactured by Asahi Kasei ・Low density ethylene: product name “LF580”, manufactured by Japan polyethylene ・Polypropylene: product name “F107A”, manufactured by Prime Polymer (adhesive layer)
・Polyethylene: Product name “KS560T” manufactured by Japan Polyethylene ・EVA resin: Product name “P1007” manufactured by Mitsui Dow

As shown in Tables 1 and 2, a surface protective film having an adhesive layer with an adhesive strength to an acrylic plate of 0.01 to 0.09 N/25 mm and a film thickness of 30 to 60 μm has a peel strength to an acrylic plate. was 0.5 N/50 mm or less. Therefore, the surface protective film is easily peeled off.
On the other hand, the adhesive strength of the adhesive layer to the acrylic plate was 0.10 N/25 mm, or the peel strength of the surface protective film having a film thickness of 70 μm to the acrylic plate was 0.6 N/50 mm. Therefore, the surface protection film is difficult to peel off.

Claims (10)

A substrate layer and a pressure-sensitive adhesive layer provided on one surface of the substrate layer,
The adhesive layer has an adhesive strength of 0.01 to 0.09 N/25 mm to the acrylic plate,
A surface protection film having a thickness of 30 to 60 μm. 2. The surface protective film according to claim 1, which has a tensile modulus of 100 to 1000 MPa. 3. The surface protection film according to claim 1, wherein the base layer has a thickness of 20 to 40 μm. The surface protection film according to any one of claims 1 to 3, wherein the pressure-sensitive adhesive layer has a thickness of 5 to 20 µm. The surface protection film according to any one of claims 1 to 4, wherein the base layer contains at least one of polyolefin resin and polyester resin. 6. The surface protective film according to claim 5, wherein said polyolefin resin is at least one selected from the group consisting of low-density polyethylene, medium-density polyethylene, high-density polyethylene, and polypropylene. The surface protection film according to any one of claims 1 to 6, wherein the pressure-sensitive adhesive layer is at least one selected from the group consisting of polyolefin resins, EVA resins, and acrylic resins. The surface protection film according to claim 7, wherein the adhesive layer is at least one selected from the group consisting of low density polyethylene, linear low density polyethylene, and EVA resin. The surface protective film according to any one of claims 1 to 8, which has a peel strength to an acrylic plate of 0.1 to 0.5 N/50 mm. 10. The surface protection film according to any one of claims 1 to 9, which is roll-shaped.

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