Surface protection film

Abstract

The present invention provides a surface protection film comprising an adhesive layer, capable of exhibiting sufficient strong adhesion to a substrate before UV irradiation and excellent light peelability that allows for smooth peeling from the substrate after UV irradiation, and also capable of maintaining such light peelability even when left attached to a substrate for a long period of time so as not to undergo heavy peeling. Furthermore, the present invention provides an optical device and an electronic device comprising such a surface protection film. A surface protection film according to an embodiment of the present invention is a surface protection film comprising an adhesive layer, wherein the adhesive constituting the adhesive layer is formed of an adhesive composition, and the adhesive composition comprises a urethane prepolymer (A), a crosslinking agent (B), and a photopolymerization initiator (C), and the surface elastic modulus of the adhesive layer is 2.00 kPa or more in an environment of 23°C and 55% RH of humidity after irradiating the adhesive with ultraviolet light of an integrated light amount of 700 mJ / cm² by an LED light source of wavelength 365 nm.

Description

Technology Field

[0001] The present invention relates to a surface protection film. Background Technology

[0002] In the manufacturing process of optical or electronic devices, a surface protection film is generally applied to the exposed surface of the optical or electronic component to prevent scratches from occurring on the surface of the optical or electronic component during processing, assembly, inspection, transportation, etc. This surface protection film is peeled off from the optical or electronic component when the need for surface protection is no longer present (Patent Document 1).

[0003] For surface protection films attached to the exposed surfaces of such optical or electronic components, it is necessary to exhibit sufficient strong adhesion so that they do not peel off easily while surface protection is required. On the other hand, when surface protection is no longer needed, excellent peelability is required to smoothly peel off the surface protection film without contamination or damage to the optical or electronic components. In other words, a combination of sufficient strong adhesion while surface protection is required and excellent peelability when surface protection is no longer needed is required.

[0004] As a technique for adjusting adhesive strength, a surface protection sheet for optical components in which adhesive strength is reduced by irradiating with ultraviolet rays has been reported (Patent Document 2). Additionally, a surface protection sheet for optical components in which adhesive strength is reduced by irradiating with ultraviolet rays to exhibit light peelability has been reported (Patent Document 3). However, the adhesive reported in Patent Document 2 cannot sufficiently increase adhesive strength before ultraviolet irradiation, nor can it sufficiently decrease adhesive strength after ultraviolet irradiation. Furthermore, the adhesive reported in Patent Document 3 cannot sufficiently decrease adhesive strength. For this reason, the compatibility of sufficient strong adhesive strength while surface protection is required and excellent light peelability at the point when surface protection is no longer required has not been achieved. Prior art literature

[0005] Japanese Patent Publication No. 6613516, Japanese Patent Publication No. 2019-116609, Japanese Patent Publication No. 2019-116610 The problem to be solved

[0006] The objective of the present invention is to provide a surface protection film comprising an adhesive layer, the primary purpose of which is to be adhered to an exposed surface to prevent scratches on the surface of an optical member or electronic member during processing, assembly, inspection, transportation, etc., in a manufacturing process of an optical device or electronic device, and which can exhibit sufficient strong adhesion to a substrate before UV irradiation, and exhibit excellent light peelability that allows it to be smoothly peeled off from the substrate after UV irradiation, and which can maintain such light peelability even when left attached to the substrate for a long period of time so as not to undergo heavy peeling. Furthermore, the invention aims to provide an optical device and an electronic device comprising such a surface protection film. means of solving the problem

[0007] [1] A surface protection film according to an embodiment of the present invention is a surface protection film comprising an adhesive layer, wherein the adhesive constituting the adhesive layer is formed from an adhesive composition, and the adhesive composition comprises a urethane prepolymer (A), a crosslinking agent (B), and a photopolymerization initiator (C), and the surface elastic modulus of the adhesive layer is 2.00 kPa or more in an environment of 23°C and 55% RH of humidity after irradiating the adhesive with ultraviolet light of 700 mJ / cm² with an integrated light amount by an LED light source of 365 nm wavelength.

[0008] [2] In the surface protection film described in [1] above, the urethane prepolymer (A) may have polymerizable unsaturated double bonds.

[0009] [3] In the surface protection film described in [2] above, the content ratio of the polymerizable unsaturated double bond in the urethane prepolymer (A) may be 0.25 mol / kg to 0.40 mol / kg.

[0010] [4] In the surface protection film described in any one of [1] to [3] above, the adhesive composition may include urethane (meth)acrylate (D).

[0011] [5] An optical device according to an embodiment of the present invention includes a surface protection film as described in any one of claims [1] to [4].

[0012] [6] An electronic device according to an embodiment of the present invention includes a surface protection film described in any one of claims [1] to [4]. Effects of the invention

[0013] According to the present invention, a surface protection film comprising an adhesive layer is provided, which is primarily intended to be adhered to an exposed surface to prevent scratches on the surface of an optical member or electronic member during processing, assembly, inspection, transportation, etc., in a manufacturing process of an optical device or electronic device. The film can exhibit sufficient strong adhesion to a substrate before UV irradiation, and excellent light peelability that allows it to be smoothly peeled off from the substrate after UV irradiation. Furthermore, the film can maintain the light peelability even when left attached to the substrate for a long period of time, thereby preventing heavy peeling. Additionally, an optical device and an electronic device comprising such a surface protection film can be provided. Brief explanation of the drawing

[0014] FIG. 1 is a schematic cross-sectional view of a surface protection film according to one embodiment of the present invention. Specific details for implementing the invention

[0015] Where the term "weight" appears in this specification, it may be replaced with "mass," which is the SI unit commonly used to represent weight.

[0016] In this specification, where the expression “(meth)acryl” is used, it means “acryl and / or methacryl”; where the expression “(meth)acrylate” is used, it means “acrylate and / or methacrylate”; where the expression “(meth)acryloyl” is used, it means “acryloyl and / or methacryloyl”; where the expression “(meth)allyl” is used, it means “allyl and / or metallyl”; and where the expression “(meth)acrolein” is used, it means “acrolein and / or methacryloyl”.

[0017] ≪≪A. Surface Protection Film≫≫

[0018] A surface protection film according to an embodiment of the present invention includes an adhesive layer. The adhesive layer may be an adhesive layer consisting of only one layer, or an adhesive layer consisting of two or more layers.

[0019] A surface protection film according to an embodiment of the present invention may include an adhesive layer, and may include any other suitable layer (component) within a range that does not impair the effects of the present invention. Such other layers may be one layer or two or more layers. Examples of such other layers include a substrate layer and a release liner (also referred to as a release sheet or separator). Typically, the surface protection film of the present invention includes a substrate layer and an adhesive layer.

[0020] FIG. 1 is a schematic cross-sectional view of a surface protection film according to one embodiment of the present invention. In FIG. 1, the surface protection film (10) comprises a substrate layer (1) and an adhesive layer (2). In FIG. 1, the substrate layer (1) and the adhesive layer (2) are directly laminated. In FIG. 1, any suitable release liner (also referred to as a release sheet or separator) may be provided on the surface of the adhesive layer (2) opposite to the substrate layer (1) for protection until use (not shown).

[0021] As described above, a surface protection film according to one embodiment of the present invention has a laminated structure in which a substrate layer, an adhesive layer, and a release liner are laminated in that order, and the release liner is the outermost layer. A surface protection film according to another embodiment of the present invention has a laminated structure in which a substrate layer and an adhesive layer are laminated in that order, and the adhesive layer is the outermost layer.

[0022] The thickness of the surface protection film according to an embodiment of the present invention is preferably 5 μm to 500 μm, may be 10 μm to 450 μm, may be 15 μm to 400 μm, and may be 20 μm to 300 μm.

[0023] A surface protection film according to an embodiment of the present invention has a surface elasticity modulus (sometimes referred to as "surface elasticity modulus after UV irradiation") of the adhesive layer constituting the adhesive layer included in the surface protection film, which is irradiated with ultraviolet light of an integrated amount of 700 mJ / cm² by an LED light source of a wavelength of 365 nm, and which is preferably 2.00 kPa or more, may be 2.50 kPa or more, may be 3.00 kPa or more, may be 3.50 kPa or more, may be 4.00 kPa or more, may be 4.50 kPa or more, may be 5.00 kPa or more, may be 5.50 kPa or more, may be 6.00 kPa or more, may be 6.50 kPa or more, may be 7.00 kPa or more. Generally, the higher the surface elastic modulus, the better; however, if it is excessively high, there is a risk that it may naturally peel off from the substrate in unintended circumstances. For this reason, as an upper limit value, for example, 20.00 kPa or less is preferable, and it may be 15.00 kPa or less, or 10.00 kPa or less. If the surface elastic modulus is within the above range, the effects of the present invention can be further manifested. If the surface elastic modulus is too low and falls outside the above range, for example, if it is left attached to the substrate for a long period after UV irradiation, it may not be able to maintain light peelability and there is a risk of heavy peeling.

[0024] A surface protection film according to an embodiment of the present invention has an adhesive layer included in the surface protection film bonded to the surface of a glass plate, and after being left for 30 minutes in an environment of 23°C and 55%RH humidity, the adhesive strength (hereinafter referred to as "initial adhesive strength before UV irradiation against the glass plate") when the surface protection film is peeled from the surface of the glass plate at a peeling angle of 180 degrees and a peeling speed of 300 mm / min in an environment of 23°C and 55%RH humidity is preferably 10 gf / 25 mm or more, and may be 100 gf / 25 mm or more, 500 gf / 25 mm or more, 1000 gf / 25 mm or more, 1300 gf / 25 mm or more, 1500 gf / 25 mm or more, 1800 gf / 25 mm or more, or 2000 gf / 25 mm or more. The higher the initial adhesion strength before UV irradiation of the glass plate, the better; however, if it is excessively high, there is a concern that sufficient peelability may not be achieved even after UV irradiation. Therefore, as an upper limit value, for example, 5000 gf / 25 mm or less is preferable, and it may be 4000 gf / 25 mm or less, 3500 gf / 25 mm or less, or 3000 gf / 25 mm or less. If the initial adhesion strength before UV irradiation of the glass plate is within the above range, the surface protection film according to the embodiment of the present invention can exhibit sufficient strong adhesion strength to the substrate, for example, before UV irradiation. If the initial adhesion strength before UV irradiation of the glass plate is too low and falls outside the above range, there is a concern that the surface protection film may peel off from the substrate while surface protection is required before UV irradiation. Furthermore, details of the method for measuring the initial adhesion strength before UV irradiation of the glass plate will be described later.

[0025] A surface protection film according to an embodiment of the present invention is formed by bonding an adhesive layer included in the surface protection film to the surface of a glass plate and irradiating it with ultraviolet light having an integrated light intensity of 700 mJ / cm² by an LED light source with a wavelength of 365 nm, and then leaving it for 30 minutes in an environment of a temperature of 23°C and a humidity of 55%RH, and then peeling the surface protection film from the surface of the glass plate at a peeling angle of 180 degrees and a peeling speed of 300 mm / min in an environment of a temperature of 23°C and a humidity of 55%RH, wherein the adhesive strength (hereinafter referred to as "initial adhesive strength after UV irradiation against the glass plate") is preferably 20.00 gf / 25 mm or less, may be 16.00 gf / 25 mm or less, may be 12.00 gf / 25 mm or less, may be 10.00 gf / 25 mm or less, or may be 8.00 gf / 25 mm It may be less than 7.00gf / 25mm, less than 6.00gf / 25mm, less than 5.50gf / 25mm, less than 5.00gf / 25mm, or less than 5.00gf / 25mm. The initial adhesion strength after UV irradiation of the glass plate is better when lower, but if it is excessively low, there is a risk that it may naturally peel off from the substrate in unintended circumstances. For this reason, as a lower limit value, for example, 1.00gf / 25mm or more is preferable, and it may be 2.00gf / 25mm or more, 2.50gf / 25mm or more, or 3.00gf / 25mm or more. If the initial adhesive strength after UV irradiation of the glass plate is within the above range, the adhesive strength becomes very low; therefore, the surface protection film according to an embodiment of the present invention can exhibit excellent light peelability, allowing it to be smoothly peeled from the substrate, for example, after UV irradiation, and can be peeled smoothly without contamination or damage to the substrate. If the initial adhesive strength after UV irradiation of the glass plate is too high and falls outside the above range, there is a risk that contamination or damage to the substrate may occur when attempting to peel it off from the substrate after UV irradiation.In addition, details of the method for measuring the initial adhesion strength after UV irradiation of the glass plate will be described later.

[0026] The surface protection film according to an embodiment of the present invention has a ratio of change in initial adhesive strength before UV irradiation of the glass plate to the initial adhesive strength after UV irradiation of the glass plate (initial adhesive strength before UV irradiation of the glass plate / initial adhesive strength after UV irradiation of the glass plate) (ratio) (which may be referred to as "ratio of change in initial adhesive strength before / after UV irradiation of the glass plate") which is preferably 5 times or more, may be 10 times or more, may be 100 times or more, may be 200 times or more, may be 300 times or more, and may be 400 times or more. The higher the ratio of change, the better, but considering ease of handling, the upper limit is preferably 10,000 times or less, may be 5,000 times or less, may be 2,000 times or less, may be 1,500 times or less, and may be 1,000 times or less. If the above change ratio is within the above range, the effects of the present invention can be further expressed, for example, sufficient strong adhesion to the substrate can be expressed before UV irradiation, and excellent light peelability that allows for smooth peeling from the substrate can be expressed after UV irradiation.

[0027] A surface protection film according to an embodiment of the present invention has an adhesive layer included in the surface protection film bonded to the surface of a glass plate, irradiated with ultraviolet light having an integrated light intensity of 700 mJ / cm² by an LED light source with a wavelength of 365 nm, and left for 1 day in an environment of a temperature of 23°C and a humidity of 55%RH; after which the surface protection film is peeled from the surface of the glass plate at a peeling angle of 180 degrees and a peeling speed of 300 mm / min in an environment of a temperature of 23°C and a humidity of 55%RH, the adhesive strength (hereinafter referred to as "adhesive strength after 1 day of UV irradiation on a glass plate") is preferably 20.00 gf / 25 mm or less, may be 16.00 gf / 25 mm or less, may be 12.00 gf / 25 mm or less, may be 10.00 gf / 25 mm or less, or may be 8.00 gf / 25 mm or less. It may be 7.00gf / 25mm or less, 6.00gf / 25mm or less, 5.50gf / 25mm or less, 5.00gf / 25mm or less, or less than 5.00gf / 25mm. After 1 day of UV irradiation of the glass plate, the adhesive strength should be as low as possible, but if it is excessively low, there is a risk that it may naturally peel off from the substrate in unintended circumstances. Therefore, as a lower limit value, for example, 1.00gf / 25mm or more is desirable, and it may be 2.00gf / 25mm or more, 2.50gf / 25mm or more, or 3.00gf / 25mm or more. If the adhesive strength is within the above range one day after UV irradiation of the glass plate, the adhesive strength is significantly reduced. Therefore, the surface protection film according to the embodiment of the present invention can maintain its peelability even after being left attached to a substrate for a long period of time after UV irradiation, for example, and can be peeled off smoothly without contamination or damage to the substrate. If the adhesive strength is too high and falls outside the above range one day after UV irradiation of the glass plate, there is a risk that contamination or damage to the substrate may occur when attempting to peel it off from the substrate.In addition, details of the method for measuring adhesive strength one day after UV irradiation of the large glass plate will be described later.

[0028] The surface protection film according to an embodiment of the present invention has a rate of increase in adhesive strength after 1 day of UV irradiation of a glass plate relative to the initial adhesive strength after UV irradiation of the glass plate ((adhesive strength after 1 day of UV irradiation of the glass plate / initial adhesive strength after UV irradiation of the glass plate) × 100%) (which may be referred to as the "rate of increase in adhesive strength after UV irradiation of the glass plate"), which is preferably 110% or less, may be 108% or less, may be 106% or less, may be 104% or less, or may be 102% or less. The lower the rate of increase, the better, but if it becomes excessively lower than 100%, there is a risk that it may naturally peel off from the substrate in an unintended situation. Therefore, the lower limit value is preferably 95% or more, for example, and may be 98% or more, 99% or more, or 100% or more. If the above increase rate is within the above range, for example, even after being left attached to a substrate for a long period after UV irradiation, light peelability can be maintained so that heavy peeling does not occur, and the substrate can be peeled off smoothly without contamination or damage. If the above increase rate is too high and outside the above range, light peelability cannot be maintained and heavy peeling occurs, so there is a risk of contamination or damage to the substrate when attempting to peel it off.

[0029] A surface protection film according to an embodiment of the present invention can be manufactured by any suitable method. As such a manufacturing method, for example, a known method for manufacturing a surface protection film comprising a substrate layer and an adhesive layer may be adopted.

[0030] The adhesive layer included in the surface protection film according to an embodiment of the present invention may be formed by a forming method generally referred to as the "direct method" or by a forming method generally referred to as the "transfer method." The direct method is a method of forming an adhesive layer by applying an adhesive composition to a substrate layer and, if necessary, performing heating, irradiation with active energy rays (ultraviolet rays, etc.) or drying. The transfer method is a method of forming an adhesive layer by applying an adhesive composition to a release liner, etc., and, if necessary, performing heating, irradiation with active energy rays (ultraviolet rays, etc.) or drying, and transferring the formed adhesive layer to a substrate layer.

[0031] Examples of the above coating methods include gravure roll coaters, reverse roll coaters, kiss roll coaters, dip roll coaters, bar coaters, knife coaters, air knife coaters, spray coaters, comma coaters, direct coaters, roll brush coaters, etc.

[0032] The above heating or drying conditions may appropriately employ methods commonly known for the formation of an adhesive layer.

[0033] ≪A-1. Release Liner≫

[0034] As a release liner, any suitable release liner may be employed within a range that does not impair the effects of the present invention. As such a release liner, for example, a known release liner bonded to the surface of an adhesive layer included in a surface protection film may be employed. Examples of such a release liner include a release liner in which the surface of a substrate (liner substrate), such as paper or a plastic film, is silicone-treated, or a release liner in which the surface of a substrate (liner substrate), such as paper or a plastic film, is laminated with a polyolefin-based resin.

[0035] Examples of plastic films used as liner substrates include polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film, polybutylene terephthalate film, polyurethane film, and ethylene-vinyl acetate copolymer film.

[0036] The thickness of the release liner is preferably 1 μm to 500 μm, may be 3 μm to 450 μm, may be 5 μm to 400 μm, or may be 10 μm to 300 μm.

[0037] ≪A-2. Adhesive Layer≫

[0038] The adhesive layer consists of an adhesive. The adhesive is formed from an adhesive composition. That is, the adhesive layer is composed of an adhesive, and the adhesive is formed from an adhesive composition. In other words, the adhesive formed from the adhesive composition constitutes a layer shape, thereby becoming an adhesive layer.

[0039] The thickness of the adhesive layer is preferably 5㎛ to 150㎛ in order to further express the effects of the present invention, and may be 10㎛ to 130㎛, 30㎛ to 120㎛, 50㎛ to 100㎛, or 60㎛ to 90㎛.

[0040] The adhesive composition comprises a urethane prepolymer (A), a crosslinking agent (B), and a photopolymerization initiator (C). In an embodiment of the present invention, the urethane prepolymer (A), the crosslinking agent (B), and the photopolymerization initiator (C) are used in combination as components included in the adhesive composition. Preferably, the type of each as described below is selected, or the amount used is adjusted, thereby enabling the effects of the present invention to be achieved.

[0041] <A-2-1. 우레탄 프리폴리머(A)>

[0042] The urethane prepolymer (A) corresponds to a polymer component generally referred to as a base polymer as a component of the adhesive composition.

[0043] The urethane prepolymer (A) may be of only one type or two or more types.

[0044] The content ratio of the urethane prepolymer (A) in the adhesive composition is preferably 50% to 99.9% by weight in terms of solid content, and may be 55% to 97% by weight or 60% to 95% by weight. If the content ratio of the urethane prepolymer (A) in the adhesive composition is within the above range in terms of solid content, the effects of the present invention can be further expressed.

[0045] The urethane prepolymer (A) can typically react with a crosslinking agent (B) (preferably a polyfunctional isocyanate compound) to form a urethane resin. More specifically, the urethane resin can preferably be formed from an adhesive composition containing the urethane prepolymer (A) and the crosslinking agent (B), and more specifically, the urethane resin can be formed by curing the adhesive composition containing the urethane prepolymer (A) and the crosslinking agent (B). As a method for forming the urethane resin by curing the adhesive composition containing the urethane prepolymer (A) and the crosslinking agent (B), any suitable method may be employed within a range that does not impair the effects of the present invention, such as a urethane reaction method using bulk polymerization or solution polymerization.

[0046] As is generally well known, there are two types of manufacturing methods for urethane resins: the "one-shot method," which produces a urethane resin by directly reacting a polyol with a crosslinking agent (preferably a polyfunctional isocyanate compound) without using a urethane prepolymer, and the "prepolymer method," which produces a urethane resin by reacting a urethane prepolymer with a crosslinking agent (preferably a polyfunctional isocyanate compound). In the present invention, the urethane prepolymer (A) as the base polymer corresponds to the urethane prepolymer that reacts with the crosslinking agent (preferably a polyfunctional isocyanate compound) in the "prepolymer method," and is different from the polyol that reacts with the polyfunctional isocyanate in the "one-shot method."

[0047] The number average molecular weight Mn of the urethane prepolymer (A) is preferably 3,000 to 1,000,000.

[0048] The urethane prepolymer (A) may have a polymerizable unsaturated double bond. By having the urethane prepolymer (A) a polymerizable unsaturated double bond, the effects of the present invention may be further expressed. As for the polymerizable unsaturated double bond, generally known polymerizable unsaturated double bonds may be included, for example, vinyl groups, (meth)allyl groups, and (meth)acryloyl groups, and in order to further express the effects of the present invention, it is preferably a (meth)acryloyl group. The (meth)acryloyl group is at least one selected from the group consisting of acryloyl groups and methacryloyl groups.

[0049] When the urethane prepolymer (A) has polymerizable unsaturated double bonds, the content ratio of the corresponding polymerizable unsaturated double bonds in the urethane prepolymer (A) is preferably 0.10 mol / kg to 0.50 mol / kg, may be 0.15 mol / kg to 0.45 mol / kg, may be 0.20 mol / kg to 0.40 mol / kg, or may be 0.25 mol / kg to 0.35 mol / kg. If the content ratio of the polymerizable unsaturated double bonds in the urethane prepolymer (A) is within the above range, the effects of the present invention may be further expressed. If the content ratio of the polymerizable unsaturated double bonds in the urethane prepolymer (A) is too low and falls outside the above range, there is a risk that sufficient strong adhesion to the substrate may not be expressed, and, for example, there is a risk that the initial adhesion strength before UV irradiation against a glass plate may be lowered. If the content ratio of polymerizable unsaturated double bonds in the urethane prepolymer (A) is too high outside the above range, there is a risk that the peeling force will become too high in the peeling process, which is performed, for example in the manufacturing process of optical devices or electronic devices, to peel off a portion of the surface protection film attached to the substrate and expose a portion of the substrate.

[0050] The urethane prepolymer (A) is preferably a polyurethane polyol.

[0051] The urethane prepolymer (A) is a polymer obtained by reacting a composition comprising, preferably, a polyol, a compound having polymerizable unsaturated double bonds, and a crosslinking agent (preferably, a polyfunctional isocyanate compound). This reaction may be carried out in the presence of a catalyst or without a catalyst.

[0052] Furthermore, in the description of the embodiments of the present invention, the term "polyol" refers to a polyol that does not contain a polymerizable unsaturated double bond. Accordingly, a compound having a polymerizable unsaturated double bond and a plurality of hydroxyl groups is considered not a "polyol" but a "compound having a polymerizable unsaturated double bond" in the description of the embodiments of the present invention.

[0053] The polyol preferably comprises at least one selected from the group consisting of polyester polyol (a1) and polyether polyol (a2).

[0054] The polyester polyol (a1) may be of only one type or two or more types.

[0055] The polyether polyol (a2) may be of only one type or two or more types.

[0056] The content of the polyol in the composition (composition comprising a polyol, a compound having a polymerizable unsaturated double bond, and a crosslinking agent) for preparing a urethane prepolymer (A) is preferably 50% to 99% by weight in terms of solid content, and may be 55% to 95% by weight or 60% to 90% by weight.

[0057] The content ratio of at least one selected from the group consisting of polyester polyol (a1) and polyether polyol (a2) among the polyols is preferably 50% to 100% by weight, may be 70% to 100% by weight, may be 80% to 100% by weight, may be 90% to 100% by weight, and may be 95% to 100% by weight.

[0058] As the polyester polyol (a1), a polyester polyol that can be normally used in the manufacture of a urethane prepolymer may be appropriately employed. Examples of such a polyester polyol (a1) include a polyester polyol obtained by reacting an acid component with a glycol component. Examples of acid components include terephthalic acid, adipic acid, azelaic acid, sebacic acid, phthalic anhydride, isophthalic acid, and trimellitic acid. Examples of glycol components include ethylene glycol, propylene glycol, diethylene glycol, butylene glycol, 1,6-hexane glycol, 3-methyl-1,5-pentanediol, 3,3'-dimethylolheptane, polyoxyethylene glycol, polyoxypropylene glycol, 1,4-butanediol, neopentyl glycol, butylethylpentanediol, glycerin, trimethylolpropane, and pentaerythritol. In addition to these, polyester polyols obtained by ring-opening polymerization of lactones such as polycaprolactone, poly(β-methyl-γ-valerolactone), and polyvalerolactone can also be cited as polyester polyols.

[0059] As for the molecular weight of the polyester polyol (a1), it can be used from low molecular weight to high molecular weight. As for the molecular weight of the polyester polyol (a1), the number average molecular weight Mn is preferably 100 to 100000, and may be 100 to 10000.

[0060] As for the polyether polyol (a2), a polyether polyol that can be normally used in the manufacture of a urethane prepolymer may be appropriately employed. Examples of such polyether polyols (a2) include polyether polyols containing two or more functional groups, such as polyethylene glycol, polypropylene glycol, and polytetramethylene glycol (sometimes referred to as polytetramethylene ether glycol), and representative examples include polyether polyols containing two or more of at least one group selected from the group consisting of methylene groups (-CH2-) and methine groups (-CH(CH3)-). If necessary, a portion of the polyether polyol may be substituted with glycols such as ethylene glycol or polyhydric amines such as ethylenediamine and used in combination.

[0061] As for the molecular weight of the polyether polyol (a2), it can be used from low molecular weight to high molecular weight. As for the molecular weight of the polyether polyol (a2), the number average molecular weight Mn is preferably 100 to 100000, and may be 100 to 10000.

[0062] As for the polyether polyol (a2), only a difunctional polyether polyol may be used, and a polyether polyol having a number average molecular weight Mn of 100 to 100000 and having at least 3 hydroxyl groups in one molecule may be used in part or in whole.

[0063] One embodiment of the polyol is an embodiment (A) comprising both a polyester polyol (a1) and a polyether polyol (a2).

[0064] In embodiment (A), the polyether polyol (a2) is a polyether polyol comprising at least two groups selected from the group consisting of methylene groups and methine groups, for example, one or more polyether polyols (a2-1) comprising at least two groups selected from the group consisting of methylene groups and methine groups, one or more polyether polyols (a2-2) comprising at least three groups selected from the group consisting of methylene groups and methine groups, or a mixture of one or more polyether polyols (a2-1) and one or more polyether polyols (a2-2).

[0065] In embodiment (A), when the polyether polyol (a2) is a mixture of one or more types of polyether polyols (a2-1) and one or more types of polyether polyols (a2-2), the weight ratio of polyether polyol (a2-2) to 100 parts by weight of polyether polyol (a2-1) is preferably 1 part by weight to 10,000 parts by weight, and may be 5 parts by weight to 1,000 parts by weight, 8 parts by weight to 150 parts by weight, or 10 parts by weight to 100 parts by weight, in order to further express the effects of the present invention.

[0066] Polyether polyols (a2-1) comprising at least two groups selected from the group consisting of methylene groups and methine groups include, for example, polyethylene glycol and polypropylene glycol.

[0067] Polyether polyols (a2-2) comprising at least three groups selected from the group consisting of methylene groups and methine groups include, for example, polytetramethylene glycol.

[0068] In embodiment (A), when the polyether polyol (a2) is one or more of the polyether polyol (a2-1), the urethane prepolymer (A) comprises an alkylene oxide backbone comprising at least two groups selected from the group consisting of methylene groups and methine groups.

[0069] In embodiment (A), when the polyether polyol (a2) is one or more of the polyether polyol (a2-2), the urethane prepolymer (A) comprises an alkylene oxide backbone comprising three or more groups selected from the group consisting typically of methylene groups and methine groups.

[0070] In embodiment (A), where the polyether polyol (a2) is a mixture of one or more polyether polyols (a2-1) and one or more polyether polyols (a2-2), the urethane prepolymer (A) comprises an alkylene oxide backbone comprising two groups selected from the group consisting of methylene groups and methine groups, typically, and an alkylene oxide backbone comprising three or more groups selected from the group consisting of methylene groups and methine groups.

[0071] In embodiment (A), the content ratio of the polyester polyol (a1) in the polyol is preferably 0.1% to 99.9% by weight, and may be 1% to 80% by weight, 5% to 60% by weight, 10% to 55% by weight, 20% to 50% by weight, or 25% to 45% by weight.

[0072] In embodiment (A), the content ratio of polyether polyol (a2) in the polyol is preferably 0.1% to 99.9% by weight, and may be 20% to 99% by weight, 40% to 95% by weight, 45% to 90% by weight, 50% to 80% by weight, or 55% to 75% by weight.

[0073] Another embodiment of the polyol is an embodiment (B) that includes a polyether polyol (a2) and does not include a polyester polyol (a1). In embodiment (B), the polyol is typically composed of a polyether polyol (a2).

[0074] In embodiment (B), the content ratio of polyether polyol (a2) in the polyol is preferably 50% to 100% by weight, and may be 70% to 100% by weight, 90% to 100% by weight, 95% to 100% by weight, or 98% to 100% by weight.

[0075] In embodiment (B), the polyether polyol (a2) is a polyether polyol comprising at least two groups selected from the group consisting of methylene groups and methine groups, for example, one or more polyether polyols (a2-1) comprising at least two groups selected from the group consisting of methylene groups and methine groups, one or more polyether polyols (a2-2) comprising at least three groups selected from the group consisting of methylene groups and methine groups, or a mixture of one or more polyether polyols (a2-1) and one or more polyether polyols (a2-2).

[0076] Polyether polyols (a2-1) comprising at least two groups selected from the group consisting of methylene groups and methine groups include, for example, polyethylene glycol and polypropylene glycol.

[0077] Polyether polyols (a2-2) comprising at least three groups selected from the group consisting of methylene groups and methine groups include, for example, polytetramethylene glycol.

[0078] In embodiment (B), when the polyether polyol (a2) is one or more of the polyether polyol (a2-1), the urethane prepolymer (A) comprises an alkylene oxide backbone comprising at least two groups selected from the group consisting of methylene groups and methine groups.

[0079] In embodiment (B), when the polyether polyol (a2) is one or more of the polyether polyol (a2-2), the urethane prepolymer (A) comprises an alkylene oxide backbone comprising three or more groups selected from the group consisting typically of methylene groups and methine groups.

[0080] In embodiment (B), where the polyether polyol (a2) is a mixture of one or more polyether polyols (a2-1) and one or more polyether polyols (a2-2), the urethane prepolymer (A) comprises an alkylene oxide backbone comprising two groups selected from the group consisting of methylene groups and methine groups, typically, and an alkylene oxide backbone comprising three or more groups selected from the group consisting of methylene groups and methine groups.

[0081] As for the compound having a polymerizable unsaturated double bond, any suitable compound may be used as long as it has a polymerizable unsaturated double bond and does not impair the effects of the present invention. The compound having a polymerizable unsaturated double bond may be one type or two or more types.

[0082] Examples of compounds having polymerizable unsaturated double bonds include compounds having vinyl groups, compounds having (meth)allyl groups, and compounds having (meth)acryloyl groups; preferably, in order to further express the effects of the present invention, the compounds having (meth)acryloyl groups are compounds. The number of polymerizable unsaturated double bonds in a compound having polymerizable unsaturated double bonds may be only one or two or more.

[0083] In order to further express the effects of the present invention, the content of the compound having a polymerizable unsaturated double bond in the above composition (a composition comprising a polyol, a compound having a polymerizable unsaturated double bond, and a crosslinking agent) is preferably 0.01 to 50 parts by weight per 100 parts by weight of polyol, and may be 0.1 to 30 parts by weight, 0.5 to 25 parts by weight, 1.0 to 20 parts by weight, or 1.5 to 15 parts by weight.

[0084] Examples of compounds having a (meth)acryloyl group include (meth)acrylic acid esters. Examples of (meth)acrylic acid esters include (meth)acrylic acid alkyl esters, hydroxyl group-containing (meth)acrylic acid esters, and nitrogen atom-containing (meth)acrylic acid esters; hydroxyl group-containing (meth)acrylic acid esters are preferred in that they can further express the effects of the present invention.

[0085] As hydroxyl group-containing (meth)acrylic acid esters, for example, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2,3-hydroxypropyl (meth)acrylate, glycerin mono(meth)acrylate, glycerin di(meth)acrylate, cyclohexanedimethanol mono(meth)acrylate, 2-hydroxy-3-phenoxypropylacrylate, isocyanuric acid EO or PO modified (meth)acrylate, isocyanuric acid EO or PO modified di(meth)acrylate, pentaerythritol tri(meth)acrylate, Examples include dipentaerythritol penta(meth)acrylate, polypentaerythritol penta(meth)acrylate, dipentaerythritol EO or PO modified penta(meth)acrylate, dipentaerythritol caprolactone modified penta(meth)acrylate, and epoxy (meth)acrylates produced by reacting the epoxy group of an epoxy compound with the carboxyl group of (meth)acrylic acid.

[0086] Among hydroxyl group-containing (meth)acrylic acid esters, a hydroxyl group-containing (meth)acrylic acid ester having two or more hydroxyl groups is preferred in that it can further express the effects of the present invention. As for hydroxyl group-containing (meth)acrylic acid esters having two or more hydroxyl groups, glycerin mono(meth)acrylate and glycerin di(meth)acrylate are preferably examples, and commercially available products include the trade name "Blemmer GLM" (manufactured by Nichiyu Co., Ltd.), the trade name "Blemmer GLM-R" (manufactured by Nichiyu Co., Ltd.), the trade name "Blemmer GMR-M" (manufactured by Nichiyu Co., Ltd.), and the trade name "Blemmer GMR-R" (manufactured by Nichiyu Co., Ltd.).

[0087] As a crosslinking agent, any suitable crosslinking agent that can be used in the manufacture of urethane prepolymers may be employed within a range that does not impair the effects of the present invention. Preferably, such a crosslinking agent is a polyfunctional isocyanate compound. The polyfunctional isocyanate compound may be one type or two or more types.

[0088] As for the polyfunctional isocyanate compound, any suitable polyfunctional isocyanate compound may be used within a range that does not impair the effects of the present invention. Examples of such polyfunctional isocyanate compounds include polyfunctional aliphatic isocyanate compounds, polyfunctional alicyclic isocyanate compounds, polyfunctional aromatic isocyanate compounds, and polyfunctional aromatic aliphatic isocyanate compounds.

[0089] Examples of polyfunctional aliphatic isocyanate compounds include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 1,3-butylene diisocyanate, 2,3-butylene diisocyanate, dodecamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, etc.

[0090] Examples of polyfunctional cycloaliphatic isocyanate compounds include 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate, 1,3-cyclopentane diisocyanate, 1,3-cyclohexanediisocyanate, 1,4-cyclohexanediisocyanate, isophorone diisocyanate, methyl-2,4-cyclohexanediisocyanate, methyl-2,6-cyclohexanediisocyanate, 4,4'-methylenebis(cyclohexyl isocyanate), 1,4-bis(isocyanatomethyl)cyclohexane, hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated tetramethylxylylene diisocyanate, etc.

[0091] Examples of polyfunctional aromatic isocyanate compounds include 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 2,2'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-toluidine diisocyanate, 2,4,6-triisocyanate toluene, 1,3,5-triisocyanate benzene, 4,4'-diphenyl ether diisocyanate, 4,4'-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, 4,4',4"-triphenylmethane triisocyanate, dianisidine diisocyanate, xylylene diisocyanate, etc.

[0092] Examples of polyfunctional aromatic aliphatic isocyanate compounds include ω,ω'-diisocyanate-1,3-dimethylbenzene, ω,ω'-diisocyanate-1,4-dimethylbenzene, ω,ω'-diisocyanate-1,4-diethylbenzene, 1,4-tetramethylxylylene diisocyanate, 1,3-tetramethylxylylene diisocyanate, etc.

[0093] Examples of polyfunctional isocyanate compounds include trimethylolpropane adducts of various polyfunctional isocyanate compounds as described above, biuret forms reacted with water, and trimers having an isocyanurate ring. In addition, these may be used in combination.

[0094] The amount of crosslinking agent that can be used to obtain a urethane prepolymer (A) is preferably 0.001 to 50 parts by weight per 100 parts by weight of polyol, and may be 0.01 to 40 parts by weight, 0.1 to 35 parts by weight, 1 to 35 parts by weight, 5 to 35 parts by weight, or 10 to 35 parts by weight.

[0095] When manufacturing the urethane prepolymer (A), a catalyst may be used. Any suitable catalyst may be used as the catalyst that can be used when manufacturing the urethane prepolymer (A). Examples of such catalysts include tertiary amine compounds and organometallic compounds. The catalyst may be of only one type or two or more types.

[0096] Examples of tertiary amine compounds include triethylamine, triethylenediamine, 1,8-diazabicyclo(5,4,0)-undecene-7 (DBU), etc.

[0097] Examples of organometallic compounds include bismuth-based catalysts such as bismuth octylate, bismuth neodecanoate, bismuth naphthenate, and bismuth rosinate; tin-based catalysts such as dibutyltin dilaurate (DBTDL) and dioctyltin dilaurate (DOTDL); titanium-based catalysts such as dibutyl titanium dichloride, tetrabutyl titanate, butoxytitanium trichloride, and titanium tetraacetylacetonate; iron-based catalysts such as iron 2-ethylhexanate and iron acetylacetonate; cobalt-based catalysts such as cobalt benzoate and cobalt 2-ethylhexanate; zinc-based catalysts such as zinc octylate, zinc naphthenate, and zinc 2-ethylhexanate; and zirconium-based catalysts such as zirconium naphthenate.

[0098] When a catalyst is used when manufacturing a urethane prepolymer (A), the amount of catalyst used is preferably 0.0001% to 1.0% by weight with respect to the total amount of the polyol, the compound having a polymerizable unsaturated double bond, and the crosslinking agent, and may be 0.001% to 1.0% by weight, 0.003% to 1.0% by weight, or 0.005% to 1.0% by weight.

[0099] When a catalyst is used to manufacture the urethane prepolymer (A), the reaction temperature is preferably less than 100°C, and may be between 60°C and 90°C. If the temperature is 100°C or higher, there is a risk that it will be difficult to control the reaction rate and the cross-linked structure.

[0100] When manufacturing the urethane prepolymer (A), a catalyst may not be used. In this case, the reaction temperature may be 100°C or higher.

[0101] As a method for preparing a urethane prepolymer (A), examples include: 1) a method of adding the entire amount of a polyol, a compound having a polymerizable unsaturated double bond, a crosslinking agent, and a catalyst to a flask; and 2) a method of adding part or all of the polyol, part or all of the compound having a polymerizable unsaturated double bond, and a catalyst to a flask, and adding part or all of the crosslinking agent. In method 2), after adding part or all of the crosslinking agent, the remainder of the polyol, the remainder of the compound having a polymerizable unsaturated double bond, and the remainder of the crosslinking agent may be added additionally.

[0102] When manufacturing the urethane prepolymer (A), any suitable solvent may be used. Examples of such solvents include methyl ethyl ketone, ethyl acetate, toluene, xylene, and acetone. Among these solvents, toluene is preferably used.

[0103] When manufacturing the urethane prepolymer (A), any suitable other component may be used in any suitable amount, provided that the effects of the present invention are not impaired. Examples of other components include crosslinking promoters, silane coupling agents, antistatic agents, antioxidants, ultraviolet absorbers, light stabilizers, other resin components, tackifiers, crosslinking retardants, inorganic fillers, organic fillers, colorants (pigments or dyes, etc.), chain transfer agents, plasticizers, softeners, anti-aging agents, conductive agents, film materials, surface lubricants, leveling agents, corrosion inhibitors, heat stabilizers, polymerization inhibitors, and lubricants. The other component may be one type or two or more types.

[0104] <A-2-2. 가교제(B)>

[0105] The urethane prepolymer (A) typically reacts with a crosslinking agent (B) to become a urethane resin. The crosslinking agent (B) may be of only one type or two or more types.

[0106] As for the crosslinking agent (B), any suitable crosslinking agent that can be used in the manufacture of urethane-based resins may be employed within a range that does not impair the effects of the present invention. Preferably, such a crosslinking agent is a polyfunctional isocyanate compound. The polyfunctional isocyanate compound may be one type or two or more types.

[0107] As a polyfunctional isocyanate compound, any suitable polyfunctional isocyanate compound that can be used in a urethane reaction may be employed. As such a polyfunctional isocyanate compound, for example, the polyfunctional isocyanate compound described above may be employed as a polyfunctional isocyanate compound that can be reacted with a polyol to obtain a urethane prepolymer (A). The polyfunctional isocyanate compound that reacts with the urethane prepolymer (A) to become a urethane-based resin may be the same as or different from the polyfunctional isocyanate compound described above as a polyfunctional isocyanate compound that can be reacted with a polyol to obtain a urethane prepolymer (A).

[0108] The equivalent ratio of the NCO group of the polyfunctional isocyanate compound to the OH group of the urethane prepolymer (A) is NCO group / OH group, preferably 0.2 to 1.8, may be 0.2 to 1.6, 0.3 to 1.4, 0.3 to 1.2, 0.4 to 1.1, 0.4 to 1.0, 0.4 to 0.9, or 0.4 to 0.8. If the equivalent ratio of the NCO group / OH group is within the above range, the effects of the present invention can be further expressed.

[0109] The content of the crosslinking agent (B) in the adhesive composition may be any appropriate amount within a range that does not impair the effects of the present invention. The content of such crosslinking agent (B) is preferably 0.4 to 13 parts by weight per 100 parts by weight of urethane prepolymer (A), and may be 0.5 to 11 parts by weight, 0.6 to 9.0 parts by weight, 0.7 to 7.0 parts by weight, 0.8 to 5.0 parts by weight, or 0.9 to 3.0 parts by weight. If the content of the crosslinking agent (B) per 100 parts by weight of urethane prepolymer (A) is within the above range, the effects of the present invention can be further expressed.

[0110] <A-2-3. 광중합 개시제(C)>

[0111] The adhesive composition includes a photopolymerization initiator (C). The photopolymerization initiator (C) may be one type or two or more types.

[0112] As a photopolymerization initiator (C), any suitable photopolymerization initiator may be employed within a range that does not impair the effects of the present invention. Examples of such photopolymerization initiators (C) include benzoin ether-based photopolymerization initiators, acetophenone-based photopolymerization initiators, α-ketol-based photopolymerization initiators, aromatic sulfonyl chloride-based photopolymerization initiators, photoactive oxime-based photopolymerization initiators, benzoin-based photopolymerization initiators, benzyl-based photopolymerization initiators, benzophenone-based photopolymerization initiators, ketal-based photopolymerization initiators, and thioxanthone-based photopolymerization initiators.

[0113] Examples of benzoin ether-based photopolymerization initiators include benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2,2-dimethoxy-1,2-diphenylethane-1-one, and anisole methyl ether. Examples of acetophenone-based photopolymerization initiators include 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexylphenyl ketone, 4-phenoxydichloroacetophenone, and 4-(t-butyl)dichloroacetophenone. Examples of α-ketol photopolymerization initiators include 2-methyl-2-hydroxypropiophenone and 1-[4-(2-hydroxyethyl)phenyl]-2-methylpropan-1-one. Examples of aromatic sulfonyl chloride photopolymerization initiators include 2-naphthalenesulfonyl chloride. Examples of photoactive oxime photopolymerization initiators include 1-phenyl-1,1-propanedione-2-(o-ethoxycarbonyl)-oxime. Examples of benzoin photopolymerization initiators include benzoin. Examples of benzyl photopolymerization initiators include benzyl. Examples of benzophenone-based photopolymerization initiators include benzophenone, benzoylbenzoic acid, 3,3'-dimethyl-4-methoxybenzophenone, polyvinylbenzophenone, and α-hydroxycyclohexylphenyl ketone. Examples of ketal-based photopolymerization initiators include benzyldimethylketal. Examples of thioxantone-based photopolymerization initiators include thioxantone, 2-chlorothioxantone, 2-methylthioxantone, 2,4-dimethylthioxantone, isopropylthioxantone, 2,4-diisopropylthioxantone, and dodecylthioxantone.

[0114] The content of the photopolymerization initiator (C) in the adhesive composition may be any appropriate amount within a range that does not impair the effects of the present invention. The content of the photopolymerization initiator (C) is preferably 0.001 to 20 parts by weight per 100 parts by weight of the urethane prepolymer (A), and may be 0.01 to 10 parts by weight or 0.1 to 5 parts by weight.

[0115] <A-2-4. 우레탄 (메트)아크릴레이트(D)>

[0116] The adhesive composition may include urethane (meth)acrylate (D). If the adhesive composition includes urethane (meth)acrylate (D), the effects of the present invention may be further expressed, and, for example, even after being left attached to a substrate for a long period of time after UV irradiation, light peelability may be maintained, thereby further suppressing heavy peeling, and peeling may be performed more smoothly without contamination or damage to the substrate.

[0117] Urethane (meth)acrylate (D) may be of type 1 or type 2 or more.

[0118] In order to further express the effects of the present invention, the content of urethane (meth)acrylate (D) in the adhesive composition is preferably 0.5 to 50 parts by weight per 100 parts by weight of urethane prepolymer (A), 1.0 to 40 parts by weight, 1.5 to 30 parts by weight, 2.0 to 20 parts by weight, 2.5 to 15 parts by weight, 3.0 to 10 parts by weight, and 3.0 to 8.0 parts by weight.

[0119] The number of functional groups of urethane (meth)acrylate (D) is preferably 2 or more, may be 3 or more, may be 3 to 20, may be 4 to 10, may be 4 to 8, or may be 6, in order to further express the effects of the present invention. If the number of functional groups of urethane (meth)acrylate (D) is within the above range, the effects of the present invention can be further expressed.

[0120] Urethane (meth)acrylate (D) preferably has a structure represented by the following general formula (1) in order to further express the effects of the present invention. If the urethane (meth)acrylate (D) has a structure represented by the following general formula (1), the effects of the present invention can be further expressed, and even after being left attached to a substrate for a long period of time after irradiation with ultraviolet rays, light peelability can be maintained, further suppressing heavy peeling, and peeling can be done more smoothly without contamination or damage to the substrate.

[0121]

[0122] Urethane (meth)acrylate (D) preferably has a structure represented by the following general formula (1a) in order to further express the effects of the present invention. If the urethane (meth)acrylate (D) has a structure represented by the following general formula (1a), the effects of the present invention can be further expressed, and, for example, even after being left attached to a substrate for a long period of time after UV irradiation, light peelability can be maintained, thereby further suppressing heavy peeling, and peeling can be done more smoothly without contamination or damage to the substrate.

[0123]

[0124] Urethane (meth)acrylate (D) preferably has a structure represented by the following general formula (2) in order to further enhance the effects of the present invention. If the urethane (meth)acrylate (D) has a structure represented by the following general formula (2), the effects of the present invention can be further enhanced, and even after being left attached to a substrate for a long period of time after irradiation with ultraviolet rays, light peelability can be maintained, further suppressing heavy peeling, and peeling can be done more smoothly without contamination or damage to the substrate.

[0125]

[0126] In general formula (2), X is a divalent aromatic group or a divalent aliphatic group.

[0127] As for the divalent aromatic group, any suitable divalent aromatic group may be adopted within a range that does not impair the effects of the present invention. As divalent aromatic groups, for example, benzene-1,4-diyl group, benzene-1,3-diyl group, benzene-1,2-diyl group, toluene-2,4-diyl group, toluene-2,5-diyl group, toluene-2,6-diyl group, 4,6-dimethylbenzene-1,3-diyl group, 2,5-dimethylbenzene-1,4-diyl group, 2,6-dimethylbenzene-1,4-diyl group, 2,4,6-trimethylbenzene-1,3-diyl group, 2,3,5,6-tetramethylbenzene-1,4-diyl group, m-xylylene-diyl group, p-xylylene-diyl group, naphthalene-1,2-diyl group, naphthalene-1,3-diyl group, naphthalene-1,4-diyl group, Examples include naphthalene-1,5-diyl group, naphthalene-1,6-diyl group, naphthalene-1,7-diyl group, naphthalene-1,8-diyl group, naphthalene-2,3-diyl group, and naphthalene-2,6-diyl group.

[0128] As a divalent aliphatic group, any suitable divalent aliphatic group may be adopted within a range that does not impair the effects of the present invention. Examples of divalent aliphatic groups include divalent chain aliphatic groups and divalent cyclic aliphatic groups.

[0129] The divalent chain aliphatic group may be straight or branched. Examples of divalent chain aliphatic groups include the methylene group, ethane-1,1-diyl group, ethane-1,2-diyl group, propane-1,1-diyl group, propane-1,3-diyl group, propane-2,2-diyl group, pentane-1,5-diyl group, and hexane-1,6-diyl group.

[0130] Examples of divalent aliphatic groups containing a cyclic structure include, for instance, divalent aliphatic groups having a cycloalkane ring structure (e.g., a cyclohexyl ring structure). Examples of divalent aliphatic groups containing a cyclic structure include groups represented by the following general formula (3). In addition, the two bonds marked with * in general formula (3) are bonds that act as divalent groups.

[0131]

[0132] Urethane (meth)acrylate (D) preferably has a molecular weight of less than 1000 so as to further express the effects of the present invention. If the molecular weight of urethane (meth)acrylate (D) is 1000 or more, there is a risk that the effects of the present invention may not be expressed.

[0133] As for the urethane (meth)acrylate (D), for example, a compound having a structure represented by the following general formula (4) can be used.

[0134]

[0135] In general formula (4), X is as described above.

[0136] <A-2-5. 그 밖의 성분>

[0137] The adhesive composition may include any suitable other components within a range that does not impair the effects of the present invention. Examples of such other components include solvents, catalysts, crosslinking promoters, silane coupling agents, antistatic agents, antioxidants, ultraviolet absorbers, light stabilizers, other resin components, tackifiers, crosslinking retarders, inorganic fillers, organic fillers, metal powders, colorants (pigments or dyes, etc.), chain transfer agents, plasticizers, softeners, anti-aging agents, conductive agents, thin films, surface lubricants, leveling agents, corrosion inhibitors, heat stabilizers, polymerization inhibitors, and lubricants. The other components may be one type or two or more types.

[0138] ≪A-3. Recording Layer≫

[0139] The base layer may be just one layer, or it may be two or more layers. The base layer may be extended.

[0140] The thickness of the substrate layer is preferably 4㎛ to 450㎛, may be 8㎛ to 400㎛, 12㎛ to 350㎛, or 16㎛ to 250㎛.

[0141] For the surface of the substrate layer where the adhesive layer is not attached, for the purpose of forming a winding body that is easy to rewind, release treatment may be performed by adding, for example, fatty acid amide, polyethyleneimine, long-chain alkyl additive, etc. to the substrate layer, or a coating layer made of any suitable release agent such as silicone-based, long-chain alkyl-based, or fluorine-based agent may be provided.

[0142] An antistatic layer may be provided on the side where the adhesive layer of the substrate layer is not attached. As the antistatic layer, any suitable antistatic layer may be employed within a range that does not impair the effects of the present invention. Such an antistatic layer may include, for example, an antistatic agent. As the antistatic agent, any suitable antistatic agent may be employed within a range that does not impair the effects of the present invention. Examples of such antistatic agents include conductive polymers, carbon nanotubes, ionic compounds, carbon, surfactants, alkali metal salts, metal oxides, and metal microparticles.

[0143] As for the material of the substrate layer, any suitable material may be adopted depending on the application. Examples include plastic, paper, metal film, nonwoven fabric, etc. Preferably, it is plastic. That is, the substrate layer is preferably a plastic film. The substrate layer may be composed of one type of material or may be composed of two or more types of materials. For example, it may be composed of two or more types of plastics.

[0144] Examples of the above plastics include polyester resins, polyamide resins, polyolefin resins, etc. Examples of polyester resins include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, etc.

[0145] The substrate layer may contain any suitable additives as needed. Examples of additives that may be contained in the substrate layer include antioxidants, UV absorbers, light stabilizers, antistatic agents, fillers, pigments, etc. The type, number, and amount of additives that may be contained in the substrate layer can be appropriately set according to the purpose. In particular, when the material of the substrate layer is plastic, it is desirable to contain several of the above additives for purposes such as preventing deterioration. From the perspective of improving weather resistance, antioxidants, UV absorbers, light stabilizers, and fillers are particularly preferably cited as additives.

[0146] ≪≪B. Uses≫≫

[0147] A surface protection film according to an embodiment of the present invention is typically adhered to an exposed surface of an optical member or an electronic member to prevent scratches on the surface of the optical member or electronic member during processing, assembly, inspection, transportation, etc., in a manufacturing process of an optical device or an electronic device, and can be suitably used for surface protection of the optical member or electronic member. An optical device according to an embodiment of the present invention includes an adhesive film according to an embodiment of the present invention. An electronic device according to an embodiment of the present invention includes an adhesive film according to an embodiment of the present invention.

[0148] Examples

[0149] The present invention will be specifically described below by way of examples, but the present invention is not limited in any way to these examples. Furthermore, the testing and evaluation methods in the examples, etc. are as follows. Also, where "part" is indicated, it means "parts by weight" unless otherwise specified, and where "%" is indicated, it means "% by weight" unless otherwise specified.

[0150] <Initial Adhesion to Glass Plate Before UV Irradiation>

[0151] A surface protection film (width 25 mm × length 140 mm) with the release liner peeled off was adhered to a glass plate (soda-lime glass, manufactured by Matsunami Glass High School Co., Ltd.) by one round trip of a 2 kg hand roller. Afterwards, the film was left for 30 minutes in an environment of 23°C and 55%RH humidity to obtain a sample for evaluation.

[0152] The obtained evaluation sample was measured using a tensile testing machine under conditions of a temperature of 23°C and a humidity of 55%RH. As the tensile testing machine, the "Autograph AG-Xplus HS 6000 mm / min high-speed model (AG-50NX plus)" manufactured by Shimadzu Seisakusho Co., Ltd. was used. After setting the evaluation sample in the tensile testing machine, the tensile test was started. The conditions for the tensile test were set as a peel angle of 180 degrees and a peel speed (tensile speed) of 300 mm / min. The load was measured when the surface protection film was peeled from the glass plate, and the average load at that time was defined as the initial adhesion strength of the surface protection film to the glass plate prior to UV irradiation.

[0153] <Initial Adhesion to Glass Plate After UV Irradiation>

[0154] A surface protection film (width 25 mm × length 140 mm) with a peeled-off release liner was adhered to a glass plate (soda-lime glass, manufactured by Matsunami Glass High School Co., Ltd.) by one round trip of a 2 kg hand roller, and then the adhesive layer was photocured by irradiating ultraviolet light with an integrated light intensity of 700 mJ / cm² using an LED light source with a wavelength of 365 nm, and then left for 30 minutes in an environment of temperature 23°C and humidity 55%RH to obtain a sample for evaluation.

[0155] The obtained evaluation sample was measured using a tensile testing machine under conditions of a temperature of 23°C and a humidity of 55%RH. As the tensile testing machine, the "Autograph AG-Xplus HS 6000 mm / min high-speed model (AG-50NX plus)" manufactured by Shimadzu Seisakusho Co., Ltd. was used. After setting the evaluation sample in the tensile testing machine, the tensile test was started. The conditions for the tensile test were set as a peel angle of 180 degrees and a peel speed (tensile speed) of 300 mm / min. The load was measured when the surface protection film was peeled from the glass plate, and the average load at that time was defined as the initial adhesion strength of the surface protection film against the glass plate after UV irradiation.

[0156] <Adhesion strength 1 day after UV irradiation on large glass plate>

[0157] A surface protection film (width 25 mm × length 140 mm) with the release liner peeled off was adhered to a glass plate (soda-lime glass, manufactured by Matsunami Glass High School Co., Ltd.) by one round trip of a 2 kg hand roller, and then the adhesive layer was photocured by irradiating ultraviolet light with an integrated light intensity of 700 mJ / cm² using an LED light source with a wavelength of 365 nm, and then left for one day in an environment of 23°C and 55% RH humidity to obtain a sample for evaluation.

[0158] The obtained evaluation sample was measured using a tensile testing machine under conditions of a temperature of 23°C and a humidity of 55%RH. As the tensile testing machine, the Shimadzu Seisakusho "Autograph AG-Xplus HS 6000 mm / min high-speed model (AG-50NX plus)" was used. After setting the evaluation sample in the tensile testing machine, the tensile test was started. The conditions for the tensile test were set as a peel angle of 180 degrees and a peel speed (tensile speed) of 300 mm / min. The load was measured when the surface protection film was peeled from the glass plate, and the average load at that time was defined as the adhesion strength of the surface protection film against the glass plate one day after UV irradiation.

[0159] <Rate of Adhesion Strength Increase After UV Irradiation on Large Glass Plates>

[0160] The rate of increase in adhesive strength after 1 day of UV irradiation of a glass plate relative to the initial adhesive strength after UV irradiation of a glass plate was defined as the rate of increase in adhesive strength after UV irradiation of a glass plate, and was calculated by the following formula.

[0161] Adhesion strength increase rate (%) after UV irradiation against glass plate = (Adhesion strength after 1 day after UV irradiation against glass plate / Initial adhesion strength after UV irradiation against glass plate) × 100 (%)

[0162] Magnification of change in initial adhesion strength before / after UV irradiation on glass plates

[0163] The ratio of the change in initial adhesion strength before UV irradiation to the initial adhesion strength after UV irradiation to the glass plate was defined as the ratio of the change in initial adhesion strength before / after UV irradiation to the glass plate, and was calculated by the following formula.

[0164] Ratio of change in initial adhesion strength versus glass plate before / after UV irradiation (x) = Initial adhesion strength versus glass plate before UV irradiation / Initial adhesion strength versus glass plate after UV irradiation

[0165] <UV 조사 후 표면 탄성률>

[0166] After photocuring the adhesive layer by irradiating the adhesive constituting the adhesive layer included in the surface protection film with ultraviolet light of an integrated light intensity of 700 mJ / cm² using an LED light source of 365 nm, the surface elastic modulus of the adhesive layer under an environment of temperature 23°C and humidity 55%RH was defined as the surface elastic modulus after UV irradiation and measured by the following method.

[0167] A nanoindenter device (Triboindenter manufactured by Hysitron Inc.) was used. An indenter was pressed into the surface of the adhesive layer of the surface protection film, from which the release liner had been peeled, to a depth of 2500 nm, and the surface elastic modulus after UV irradiation was calculated using the nanoindenter device. The surface elastic modulus after UV irradiation was calculated as follows.

[0168] Surface modulus after UV irradiation (Unit: MPa) = Pmax / A

[0169] Pmax: Maximum load (Unit: μN)

[0170] A: Contact projected area (Unit: μm) 2 )

[0171] The measurement conditions were as follows.

[0172] Indenter approach speed: 1㎛ / s

[0173] Maximum displacement: 2500 nm

[0174] Indentation speed: 0.5㎛ / s

[0175] Drawing speed: 0.5㎛ / s

[0176] Indenter used: Conical (Spherical indenter: Radius of curvature 10㎛)

[0177] Measurement method: Single indentation measurement

[0178] Measurement environment: Temperature 23℃, Humidity 55%RH

[0179] <Separation ability>

[0180] The adhesive layer constituting the adhesive layer included in the surface protection film (width 25 mm × length 140 mm) was photocured by irradiating the adhesive with an integrated light intensity of 700 mJ / cm² using an LED light source with a wavelength of 365 nm.

[0181] Afterwards, using a CO2 laser, a half-cut was performed at a position 50 mm from the longitudinal end of the surface protection film under the following conditions. That is, a cut of 25 mm in width × 50 mm in length was made so that the half-cut portion was at a position of 25 mm in width.

[0182] CO2 laser wavelength: 9.36㎛

[0183] Processing speed: 500 mm / sec

[0184] Frequency: 15Hz

[0185] W number: Adjusted according to the total thickness of the surface protection film so that the uncut portion of the processed product is 40㎛.

[0186] After the half-cut, the release liner was peeled off to prepare an evaluation sample, and the peeling force was measured using a tensile testing machine under conditions of a temperature of 23°C and a humidity of 55%RH. As the tensile testing machine, the Shimadzu Seisakusho "Autograph AG-Xplus HS 6000 mm / min high-speed model (AG-50NX plus)" was used. After setting the evaluation sample in the tensile testing machine, the tensile test was started. The conditions for the tensile test were set to a peeling speed (tensile speed): 1000 mm / min. The load at which the half-cut portion was peeled off was measured, and the maximum load at that time was defined as the peeling force of the surface protection film.

[0187] The detachment force measured by the above method is preferably 30 N / 25 mm or less, and may be 27 N / 25 mm or less, 25 N / 25 mm or less, or 23 N / 25 mm or less.

[0188] [Preparation Example 1] Urethane Prepolymer A

[0189] In a polymerization apparatus equipped with a 1L round-bottom separable flask, separable cover, separable lot, thermometer, dry air inlet tube, Livbit condenser, vacuum seal, stirring rod, and stirring blade, 66.0g of polytetramethylene glycol (product name "PTMG3000", manufactured by Mitsubishi Chemical Co., Ltd.), 119.0g of polyester polyol (product name "Curare Polyol P-2010", manufactured by Curare Co., Ltd.), 16.6g of a polymerizable compound having unsaturated double bonds (product name "Blemmer GLM", manufactured by Nichiyu Co., Ltd.), and 190g of toluene (manufactured by Tosho Co., Ltd.) as a solvent were added, and while stirring, 0.09g of bismuth octylate (manufactured by Nihon Kagaku Sangyo Co., Ltd.) was added as a catalyst, and dry air evacuation was carried out at room temperature for 2 hours. Subsequently, 39.6 g of hexamethylene diisocyanate (product name "HDI", manufactured by Tosho Co., Ltd.) was added, and the solution temperature in the experimental apparatus was controlled to 80±2°C in a water bath with dry air introduced, and maintained for 5 hours. Then, 191.7 g of polypropylene glycol (product name "Sannix GP-1500", manufactured by Sanyo Kasei Co., Ltd.) was added, and the solution temperature in the experimental apparatus was controlled to 80±2°C in a water bath, and maintained for 2 hours. After that, 16.9 g of hexamethylene diisocyanate (product name "HDI", manufactured by Tosho Co., Ltd.) was added, and the solution temperature in the experimental apparatus was controlled to 80±2°C in a water bath, and maintained for 2 hours to obtain a solution of urethane prepolymer A. In addition, during polymerization, toluene was added dropwise in an appropriate amount to control the temperature during polymerization and to prevent a decrease in stirring ability due to an increase in viscosity. The solid content concentration of the solution of urethane prepolymer A was 60 wt%.

[0190] The formulations, etc. are shown in Table 1.

[0191] [Preparation Example 2] Urethane Prepolymer B

[0192] In a polymerization apparatus equipped with a 1L round-bottom separable flask, separable cover, separable lot, thermometer, dry air inlet tube, Livbit condenser, vacuum seal, stirring rod, and stirring blade, 39.1g of polytetramethylene glycol (product name "PTMG3000", manufactured by Mitsubishi Chemical Co., Ltd.), 111.9g of polyester polyol (product name "Curare Polyol P-2010", manufactured by Curare Co., Ltd.), 39.1g of a polymerizable compound having unsaturated double bonds (product name "Blemmer GLM", manufactured by Nichiyu Co., Ltd.), and 190g of toluene (manufactured by Tosho Co., Ltd.) as a solvent were added, and while stirring, 0.09g of bismuth octylate (manufactured by Nihon Kagaku Sangyo Co., Ltd.) was added as a catalyst, and dry air evacuation was carried out at room temperature for 2 hours. Subsequently, 60.5 g of hexamethylene diisocyanate (product name "HDI", manufactured by Tosho Co., Ltd.) was added, and dry air was introduced, and the solution temperature in the experimental apparatus was controlled to 80±2°C in a water bath and maintained for 5 hours. Then, 183.8 g of polypropylene glycol (product name "Sannix GP-1500", manufactured by Sanyo Kasei Co., Ltd.) was added, and the solution temperature in the experimental apparatus was controlled to 80±2°C in a water bath and maintained for 2 hours. After that, 15.4 g of hexamethylene diisocyanate (product name "HDI", manufactured by Tosho Co., Ltd.) was added, and the solution temperature in the experimental apparatus was controlled to 80±2°C in a water bath and maintained for 2 hours to obtain a solution of urethane prepolymer B. In addition, during polymerization, toluene was added dropwise in an appropriate amount to control the temperature during polymerization and to prevent a decrease in stirring ability due to an increase in viscosity. The solid content concentration of the solution of urethane prepolymer B was 60 wt%.

[0193] The formulations, etc. are shown in Table 1.

[0194] [Preparation Example 3] Urethane Prepolymer C

[0195] In a polymerization apparatus equipped with a 1L round-bottom separable flask, separable cover, separable lot, thermometer, dry air inlet tube, Livbit condenser, vacuum seal, stirring rod, and stirring blade, 89.8g of polytetramethylene glycol (product name "PTMG3000", manufactured by Mitsubishi Chemical Co., Ltd.), 112.3g of polyester polyol (product name "Curare Polyol P-2010", manufactured by Curare Co., Ltd.), 62.9g of a polymerizable compound having unsaturated double bonds (product name "Blemmer GLM", manufactured by Nichiyu Co., Ltd.), and 250g of toluene (manufactured by Tosho Co., Ltd.) as a solvent were added, and while stirring, 0.09g of bismuth octylate (manufactured by Nihon Kagaku Sangyo Co., Ltd.) was added as a catalyst, and dry air evacuation was carried out at room temperature for 2 hours. Subsequently, 84.5 g of hexamethylene diisocyanate (product name "HDI", manufactured by Tosho Co., Ltd.) was added, and dry air was introduced, and the solution temperature in the experimental apparatus was controlled to 80±2°C and maintained for 5 hours in a water bath. Then, 95.7 g of polypropylene glycol (product name "Sannix GP-1500", manufactured by Sanyo Kasei Co., Ltd.) was added, and the solution temperature in the experimental apparatus was controlled to 80±2°C and maintained for 2 hours in a water bath. After that, 6.3 g of hexamethylene diisocyanate (product name "HDI", manufactured by Tosho Co., Ltd.) was added, and the solution temperature in the experimental apparatus was controlled to 80±2°C and maintained for 2 hours in a water bath to obtain a solution of urethane prepolymer C. In addition, during polymerization, toluene was added dropwise in an appropriate amount to control the temperature during polymerization and to prevent a decrease in stirring ability due to an increase in viscosity. The solid content concentration of the solution of urethane prepolymer C was 60 wt%.

[0196] The formulations, etc. are shown in Table 1.

[0197] [Preparation Example 4] Urethane Prepolymer D

[0198] In a polymerization apparatus equipped with a 1L round-bottom separable flask, separable cover, separable lot, thermometer, nitrogen inlet tube, Leavitt condenser, vacuum seal, stirring rod, and stirring blade, 150.0g of polypropylene glycol (product name "Sannix PP-2000", manufactured by Sanyo Kasei Kogyo Co., Ltd.), 150.0g of polymerizable carbon double bond-containing diol (product name "Epoxyester 200PA", manufactured by Kyoesha Chemical Co., Ltd.), 272.0g of toluene as a solvent (manufactured by Tosho Co., Ltd.), 0.20g of dibutyltin(IV) dilaurate as a catalyst (manufactured by Wako Junyaku Kogyo Co., Ltd.), and 4.0g of an antioxidant (product name "Irganox 1010", manufactured by BASF) were added, and while stirring, dry air evacuation was performed at room temperature for 1 hour. Thereafter, 76.0 g of hexamethylene diisocyanate (product name "HDI", manufactured by Tosho Co., Ltd.) was added while stirring under dry air inflow, and after maintaining the solution temperature in the experimental apparatus in a water bath at 65±2℃ for 8 hours, 22.0 g of polymerizable carbon double bond containing diol (product name "Epoxyester 200PA", manufactured by Kyoesha Chemical Co., Ltd.) and 15.0 g of polymerizable carbon double bond containing triol (product name "Denacol Acrylate DA314", manufactured by Nagase Chemtex Co., Ltd.) were added, and the solution temperature in the experimental apparatus in a water bath was maintained at 65±2℃ for 8 hours to obtain a solution of urethane prepolymer D. In addition, during polymerization, toluene was added dropwise in an appropriate amount to control the temperature during polymerization and to prevent a decrease in stirring ability due to an increase in viscosity. The solid content concentration of the solution of urethane prepolymer D was 60 wt%.

[0199] The formulations, etc. are shown in Table 1.

[0200]

[0201] [Example 1]

[0202] Urethane prepolymer A obtained in Example 1 of preparation: 100 parts by weight, isocyanate compound (Coronate HX:C / HX, manufactured by Nippon Polyurethane Co., Ltd.) as a crosslinking agent: 2.2 parts by weight, Irganox 1010 (manufactured by BASF) as an antioxidant: 1.0 parts by weight, Omnirad 651 (manufactured by IGM Resins BV) as a photopolymerization initiator: 1.0 parts by weight, and Envirizer OL-1 (manufactured by Tokyo Fine Chemical Co., Ltd.) as a catalyst: 0.03 parts by weight were diluted with ethyl acetate so that the total solid content was 50% by weight, and a urethane-based adhesive composition (1) was obtained.

[0203] The obtained urethane-based adhesive composition (1) was applied to a substrate made of polyester resin (product name "T100-75S", manufactured by Mitsubishi Chemical Co., Ltd., thickness 75 μm) such that the thickness after drying was 75 μm, and cured under conditions of a drying temperature of 110°C and a drying time of 3 minutes to produce an adhesive layer (1) on the substrate. Subsequently, a silicone-treated surface of a release liner made of polyester resin (product name "MRF25", manufactured by Mitsubishi Chemical Co., Ltd., thickness 25 μm), having silicone treatment on one side, was bonded to the surface of the obtained adhesive layer (1), and a surface protection film (1) was obtained with the composition of a release liner (thickness 25 μm) / adhesive layer (1) (thickness 75 μm) / substrate (thickness 75 μm). The obtained surface protection film (1) was aged at room temperature for 5 days and evaluated.

[0204] The results are shown in Table 2.

[0205] [Example 2]

[0206] Except for using 100 parts by weight of urethane prepolymer B obtained in Preparation Example 2 instead of 100 parts by weight of urethane prepolymer A obtained in Preparation Example 1, and changing the amount of crosslinking agent (coronate HX) used to 2.3 parts by weight, the same procedure as in Example 1 was performed to obtain a urethane-based adhesive composition (2) and a surface protection film (2) composed of a release liner (thickness 25 μm) / adhesive layer (2) (thickness 75 μm) / substrate (thickness 75 μm). The obtained surface protection film (2) was aged at room temperature for 5 days and evaluated.

[0207] The results are shown in Table 2.

[0208] [Example 3]

[0209] Except for using 100 parts by weight of urethane prepolymer C obtained in Preparation Example 3 instead of 100 parts by weight of urethane prepolymer A obtained in Preparation Example 1, and changing the amount of crosslinking agent (coronate HX) used to 1.8 parts by weight, the same procedure as in Example 1 was performed to obtain a urethane-based adhesive composition (3) and a surface protection film (3) composed of a release liner (thickness 25 μm) / adhesive layer (3) (thickness 75 μm) / substrate (thickness 75 μm). The obtained surface protection film (3) was aged at room temperature for 5 days and evaluated.

[0210] The results are shown in Table 2.

[0211] [Example 4]

[0212] Except for using 100 parts by weight of urethane prepolymer B obtained in Preparation Example 2 instead of 100 parts by weight of urethane prepolymer A obtained in Preparation Example 1, and changing the amount of crosslinking agent (coronate HX) used to 1.4 parts by weight, the same procedure as in Example 1 was performed to obtain a urethane-based adhesive composition (4) and a surface protection film (4) composed of a release liner (thickness 25 μm) / adhesive layer (4) (thickness 75 μm) / substrate (thickness 75 μm). The obtained surface protection film (4) was aged at room temperature for 5 days and evaluated.

[0213] The results are shown in Table 2.

[0214] [Example 5]

[0215] 100 parts by weight of urethane prepolymer B obtained in Preparation Example 2, 1.4 parts by weight of isocyanate compound (Coronate HX:C / HX, manufactured by Nippon Polyurethane Co., Ltd.) as a crosslinking agent, 5 parts by weight of UA-1100H (manufactured by Shin-Nakamura Kagaku Co., Ltd.) as a urethane (meth)acrylate, 1.0 parts by weight of Irganox 1010 (manufactured by BASF) as an antioxidant, 1.0 parts by weight of Omnirad 651 (manufactured by IGM Resins BV) as a photopolymerization initiator, and 0.03 parts by weight of Envirizer OL-1 (manufactured by Tokyo Fine Chemical Co., Ltd.) as a catalyst, were diluted with ethyl acetate so that the total solid content was 50% by weight, and a urethane-based adhesive composition (5) was obtained.

[0216] The obtained urethane-based adhesive composition (5) was applied to a substrate made of polyester resin (product name “T100-75S”, manufactured by Mitsubishi Chemical Co., Ltd., thickness 75㎛) such that the thickness after drying was 75㎛, and cured and dried under conditions of a drying temperature of 110℃ and a drying time of 3 minutes to produce an adhesive layer (5) on the substrate. Subsequently, a silicone-treated surface of a release liner made of polyester resin (product name “MRF25”, manufactured by Mitsubishi Chemical Co., Ltd., thickness 25㎛), having silicone treatment on one side, was bonded to the surface of the obtained adhesive layer (5), and a surface protection film (5) was obtained with the composition of a release liner (thickness 25㎛) / adhesive layer (5) (thickness 75㎛) / substrate (thickness 75㎛). The obtained surface protection film (5) was aged at room temperature for 5 days and evaluated.

[0217] The results are shown in Table 2.

[0218] [Example 6]

[0219] Except for using 5 parts by weight of UA-306T (manufactured by Kyoesha Chemical Co., Ltd.) instead of 5 parts by weight of UA-1100H (manufactured by Shin-Nakamura Chemical Co., Ltd.) as the urethane (meth)acrylate, the same procedure as in Example 5 was performed to obtain a urethane-based adhesive composition (6), a surface protection film (6) composed of a release liner (thickness 25 μm) / adhesive layer (6) (thickness 75 μm) / substrate (thickness 75 μm). The obtained surface protection film (6) was aged at room temperature for 5 days and evaluated.

[0220] The results are shown in Table 2.

[0221] [Example 7]

[0222] Except for using 5 parts by weight of A-DPH (manufactured by Shin-Nakamura Chemical Co., Ltd.) instead of 5 parts by weight of UA-1100H (manufactured by Shin-Nakamura Chemical Co., Ltd.) as the urethane (meth)acrylate, the same procedure as in Example 5 was performed to obtain a urethane-based adhesive composition (7), a surface protection film (7) composed of a release liner (thickness 25 μm) / adhesive layer (7) (thickness 75 μm) / substrate (thickness 75 μm). The obtained surface protection film (7) was aged at room temperature for 5 days and evaluated.

[0223] The results are shown in Table 2.

[0224] [Comparative Example 1]

[0225] A surface protection film (C1) was obtained in the same manner as in Example 1, except that 100 parts by weight of the urethane prepolymer D obtained in Example 4 was used instead of 100 parts by weight of the urethane prepolymer A obtained in Example 1, and the amount of crosslinking agent (coronate HX) used was changed to 5.0 parts by weight, and the drying temperature after applying the urethane-based adhesive composition to the substrate was changed to 130°C. The surface protection film (C1) was obtained with the composition of a urethane-based adhesive composition (C1), a release liner (thickness 25 μm), an adhesive layer (C1) (thickness 75 μm), and a substrate (thickness 75 μm). The obtained surface protection film (C1) was aged at room temperature for 5 days and evaluated.

[0226] The results are shown in Table 2.

[0227] Industrial applicability

[0228] The surface protection film of the present invention can be used for any suitable application. Preferably, the surface protection film of the present invention is preferably used in the field of optical devices or electronic devices. Explanation of the symbols

[0229] 1: Base layer 2: Adhesive layer 10: Surface protection film

Claims

Claim 1 A surface protection film comprising an adhesive layer, wherein the adhesive constituting the adhesive layer is formed as an adhesive composition, and the adhesive composition comprises a urethane prepolymer (A), a crosslinking agent (B), and a photopolymerization initiator (C), and the surface elastic modulus of the adhesive layer is 2.00 kPa or more in an environment of temperature 23°C and humidity 55% RH after irradiating the adhesive with ultraviolet light of an integrated light amount of 700 mJ / cm² by an LED light source of wavelength 365 nm. Claim 2 A surface protection film according to claim 1, wherein the urethane prepolymer (A) has polymerizable unsaturated double bonds. Claim 3 A surface protection film according to claim 2, wherein the content ratio of the polymerizable unsaturated double bond in the urethane prepolymer (A) is 0.25 mol / kg to 0.40 mol / kg. Claim 4 A surface protection film according to claim 1, wherein the adhesive composition comprises urethane (meth)acrylate (D). Claim 5 An optical device comprising a surface protection film described in any one of claims 1 to 4. Claim 6 An electronic device comprising a surface protection film described in any one of claims 1 to 4.

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