Surface protective film

Abstract

To provide a surface protective film that can effectively suppress generation of bubbles when subjected to high-temperature and high-pressure treatment after an adhesive layer is attached to an adherend and then returned to ordinary temperature and pressure, and further to provide an optical device and an electronic device comprising the surface protective film.SOLUTION: According to an embodiment of the present invention, a surface protective film is provided which comprises an adhesive layer, the adhesive layer having a loss tangent at 20°C in a dynamic viscoelastic spectrum at a frequency of 0.001 Hz of 0.07 or more.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a surface protection film, and to optical and electronic devices that include such a surface protection film. [Background technology]

[0002] BACKGROUND ART In the manufacturing process of optical devices and electronic devices, surface protection films having pressure-sensitive adhesive layers are used to prevent scratches on the surfaces of optical and electronic components and to impart impact resistance during processing, assembly, inspection, transportation, and the like.

[0003] In order to pressure-bond the pressure-sensitive adhesive layer to the adherend after it has been attached to the adherend, the surface protection film may be subjected to high-temperature, high-pressure treatment using an autoclave, etc. After such high-temperature, high-pressure treatment, it is necessary to return the film to room temperature and normal pressure.

[0004] However, conventional surface protection films have the problem that when the adhesive layer is attached to an adherend, subjected to high-temperature and high-pressure treatment, and then returned to room temperature and normal pressure, air bubbles (typically small air bubbles approximately several millimeters in diameter) are likely to form at the interface between the adhesive layer and the adherend at the cut end.

[0005] A technology has been reported for suppressing the formation of bubbles when a surface protection panel and an image display panel are bonded together with a full-surface adhesive sheet and then autoclaved (Patent Document 1). Patent Document 1 reports that by appropriately adjusting the storage modulus of the adhesive layer of the full-surface adhesive sheet and setting the loss tangent of the dynamic viscoelastic spectrum at a frequency of 1 Hz and 20°C to 0.6 to 1.5, it becomes difficult for bubbles to be mixed in, and even if bubbles are mixed in, they can be removed by autoclaving or the like, and the formation of bubbles can be suppressed even at high temperatures.

[0006] However, with reference to Patent Document 1, several surface protection films having adhesive layers with storage moduli appropriately adjusted and loss tangents at a frequency of 1 Hz adjusted to various values were manufactured, and when each was autoclaved, it was found that even when the loss tangents at a frequency of 1 Hz were at the same level, bubbles sometimes formed and sometimes did not, and there was no clear correlation between the value of the loss tangent at a frequency of 1 Hz and the presence or absence of bubble suppression effect, i.e., the loss tangent at a frequency of 1 Hz was not an appropriate indicator of bubble suppression. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-231358 Summary of the Invention [Problem to be solved by the invention]

[0008] An object of the present invention is to provide a surface protection film that can sufficiently suppress the generation of bubbles even when subjected to high-temperature and high-pressure treatment after the pressure-sensitive adhesive layer is attached to an adherend and then returned to room temperature and normal pressure, and also to provide optical devices and electronic devices that include such a surface protection film. [Means for solving the problem]

[0009] The present inventors have conducted extensive research to solve the above-mentioned problems. As a result, they produced several surface protection films having pressure-sensitive adhesive layers with loss tangents adjusted to various values under these conditions, and attached them to adherends and subjected them to high-temperature, high-pressure treatment. It was found that the loss tangent at a low frequency of 0.001 Hz is an appropriate indicator of bubble suppression. As a result, they found that the above-mentioned problems can be solved by adjusting the loss tangent at a low frequency of 0.001 Hz to a specific range, which led to the completion of the present invention.

[0010] [1] A surface protection film according to an embodiment of the present invention is a surface protection film including a pressure-sensitive adhesive layer, in which the loss tangent of the dynamic viscoelasticity spectrum at 20°C at a frequency of 0.001 Hz is 0.07 or more. [2] In the surface protection film according to the above [1], the pressure-sensitive adhesive layer may have a gel fraction of 70% or more. [3] In the surface protection film according to the above [1] or [2], the pressure-sensitive adhesive layer may have a thickness of 0.5 μm to 100 μm. [4] In the surface protection film described in any one of [1] to [3] above, the adhesive layer may be attached to the surface of an acrylic plate, left for 30 minutes in an environment of a temperature of 23°C and a humidity of 50% RH, and then the adhesive strength may be 0.5 N / 25 mm or less when the surface protection film is peeled from the surface of the acrylic plate at a peel angle of 180 degrees and a peel speed of 300 mm / min in an environment of a temperature of 23°C and a humidity of 50% RH. [5] An optical device according to an embodiment of the present invention includes the surface protection film according to any one of [1] to [4] above. [6] An electronic device according to an embodiment of the present invention includes the surface protection film according to any one of [1] to [4] above. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a surface protection film that can sufficiently suppress the generation of bubbles even when the pressure-sensitive adhesive layer is attached to an adherend, subjected to high-temperature and high-pressure treatment, and then returned to room temperature and normal pressure. It is also possible to provide optical devices and electronic devices that include such a surface protection film. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a schematic cross-sectional view of a surface protection film according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0013] In this specification, the term "(meth)acrylic" means "acrylic and / or methacrylic," the term "(meth)acrylate" means "acrylate and / or methacrylate," the term "(meth)allyl" means "allyl and / or methallyl," and the term "(meth)acrolein" means "acrolein and / or methacrolein." Furthermore, in this specification, the term "acid (salt)" means "acid and / or its salt." Examples of salts include alkali metal salts and alkaline earth metal salts, and specific examples include sodium salts and potassium salts.

[0014] ≪≪1. Surface protection film≫≫ The surface protection film according to the embodiment of the present invention includes a pressure-sensitive adhesive layer.

[0015] The surface protection film according to the embodiment of the present invention may include any appropriate other layer as long as it includes a pressure-sensitive adhesive layer. Such other layer may be a single layer or two or more layers. Examples of such other layers include a substrate layer, a release liner (also called a release sheet or separator), an antistatic layer, and an antifouling layer.

[0016] A surface protection film according to a representative embodiment of the present invention includes a pressure-sensitive adhesive layer and a substrate layer. The surface protection film according to one representative embodiment of the present invention has a laminated structure in which the pressure-sensitive adhesive layer and the substrate layer are laminated in this order, and the pressure-sensitive adhesive layer is the outermost layer.

[0017] A surface protection film according to another exemplary embodiment of the present invention has a laminated structure in which a release liner, a pressure-sensitive adhesive layer, and a substrate layer are laminated in this order, with the release liner being the outermost layer.

[0018] The thickness of the surface protection film according to the embodiment of the present invention is preferably 10 μm to 500 μm, more preferably 15 μm to 400 μm, even more preferably 20 μm to 350 μm, still more preferably 25 μm to 300 μm, particularly preferably 30 μm to 200 μm, and most preferably 35 μm to 100 μm.

[0019] Figure 1 is a schematic cross-sectional view of a surface protection film according to one embodiment of the present invention. In Figure 1, surface protection film 100 comprises a release liner 10, a pressure-sensitive adhesive layer 20, and a base layer 30. In the embodiment shown in Figure 1, release liner 10 and pressure-sensitive adhesive layer 20 are laminated directly to each other, and pressure-sensitive adhesive layer 20 and base layer 30 are laminated directly to each other. Release liner 10 can be peeled off when in use.

[0020] In the surface protection film according to an embodiment of the present invention, the adhesive layer is attached to the surface of an acrylic plate, left for 30 minutes in an environment at a temperature of 23°C and a humidity of 50% RH, and then peeled from the surface of the acrylic plate at a peel angle of 180° and a peel rate of 300 mm / min in an environment at a temperature of 23°C and a humidity of 50% RH. The adhesive strength is preferably 0.5 N / 25 mm or less, more preferably 0.45 N / 25 mm or less, even more preferably 0.4 N / 25 mm or less, particularly preferably 0.35 N / 25 mm or less, and most preferably 0.3 N / 25 mm or less. When the adhesive strength is within the above range, the surface protection film can have good removability. When the adhesive strength is too high outside the above range, the removability decreases, and the film may not be suitable as a surface protection film. The lower limit of the adhesive strength is preferably 0.01 N / 25 mm or more, more preferably 0.03 N / 25 mm or more, and even more preferably 0.05 N / 25 mm or more. If the lower limit of the adhesive strength is too low, there is a risk that the adhesive may easily peel off from the adherend even while the surface is being protected. The method for measuring the adhesive strength will be described in detail later.

[0021] The surface protection film according to the embodiment of the present invention can be produced by any suitable method, for example, a known method for producing a surface protection film including a substrate layer and a pressure-sensitive adhesive layer.

[0022] The pressure-sensitive adhesive layer included in the surface protection film according to an embodiment of the present invention may be formed by a formation method generally referred to as a "direct method" or a formation method generally referred to as a "transfer method." The direct method is a method in which a pressure-sensitive adhesive composition according to an embodiment of the present invention is applied to a substrate layer, and if necessary, heating, irradiation with active energy rays (such as ultraviolet rays), drying, etc. are performed to form a pressure-sensitive adhesive layer. The transfer method is a method in which a pressure-sensitive adhesive composition according to an embodiment of the present invention is applied to a release paper or the like, dried, to form a pressure-sensitive adhesive layer, and the formed pressure-sensitive adhesive layer is transferred to a substrate layer.

[0023] Examples of the application method include a gravure roll coater, reverse roll coater, kiss roll coater, dip roll coater, bar coater, knife coater, air knife coater, spray coater, comma coater, direct coater, and roll brush coater.

[0024] <1-1. Adhesive layer> The surface protection film according to the embodiment of the present invention includes a pressure-sensitive adhesive layer. The pressure-sensitive adhesive layer may be a single layer or may be two or more layers. The pressure-sensitive adhesive layer is typically a single layer.

[0025] The thickness of the pressure-sensitive adhesive layer is preferably 0.5 μm to 100 μm, more preferably 1 μm to 70 μm, even more preferably 1.5 μm to 50 μm, still more preferably 2 μm to 40 μm, particularly preferably 2.5 μm to 30 μm, and most preferably 3 μm to 25 μm.

[0026] The pressure-sensitive adhesive layer has a loss tangent of 0.07 or more at 20°C in the dynamic viscoelasticity spectrum at a frequency of 0.001 Hz. In the surface protection film according to the embodiment of the present invention, by adjusting the loss tangent at low frequencies as described above within the above range, the generation of bubbles can be sufficiently suppressed even when the pressure-sensitive adhesive layer is attached to an adherend, subjected to high-temperature and high-pressure treatment, and then returned to room temperature and normal pressure. If the loss tangent at low frequencies as described above is small and outside the above range, for example, when the pressure-sensitive adhesive layer is attached to an adherend, subjected to high-temperature and high-pressure treatment, and then returned to room temperature and normal pressure, bubbles (typically small bubbles approximately several millimeters in diameter) may be generated at the interface between the pressure-sensitive adhesive layer and the adherend at the cut end. The upper limit of the loss tangent is preferably 0.25 or less.

[0027] In the surface protection film according to the embodiment of the present invention, as described above, the loss tangent at a low frequency of 0.001 Hz for the pressure-sensitive adhesive layer can be an appropriate indicator of bubble suppression. By adjusting the loss tangent at such a low frequency within the specific range described above, for example, even if the pressure-sensitive adhesive layer is attached to an adherend, subjected to high-temperature and high-pressure treatment, and then returned to room temperature and normal pressure, the generation of bubbles can be sufficiently suppressed.

[0028] The pressure-sensitive adhesive layer preferably has a gel fraction of 70% or more, more preferably 75% to 100%, even more preferably 80% to 100%, particularly preferably 83% to 100%, and most preferably 86% to 100%. When the gel fraction of the pressure-sensitive adhesive layer is within the above range, for example, a surface protection film with better removability can be provided.

[0029] The pressure-sensitive adhesive layer is composed of a pressure-sensitive adhesive. The pressure-sensitive adhesive is formed from a pressure-sensitive adhesive composition. That is, the pressure-sensitive adhesive layer is composed of a pressure-sensitive adhesive formed from a pressure-sensitive adhesive composition.

[0030] As the pressure-sensitive adhesive layer, any appropriate pressure-sensitive adhesive layer can be used as long as it does not impair the effects of the present invention, such as an acrylic pressure-sensitive adhesive layer composed of an acrylic pressure-sensitive adhesive, a urethane pressure-sensitive adhesive layer composed of a urethane pressure-sensitive adhesive, a silicone pressure-sensitive adhesive layer composed of a silicone pressure-sensitive adhesive, a rubber pressure-sensitive adhesive layer composed of a rubber pressure-sensitive adhesive, etc. In terms of being able to further exhibit the effects of the present invention, the pressure-sensitive adhesive layer is preferably an acrylic pressure-sensitive adhesive layer composed of an acrylic pressure-sensitive adhesive.

[0031] Hereinafter, an acrylic pressure-sensitive adhesive composition that forms an acrylic pressure-sensitive adhesive will be described as a typical example of the pressure-sensitive adhesive composition.

[0032] <1-1-a. Acrylic resin> The acrylic pressure-sensitive adhesive composition contains an acrylic resin as a base polymer, and the acrylic resin may be one type only or two or more types.

[0033] The content of the acrylic resin as a base polymer in the acrylic pressure-sensitive adhesive composition is typically, in terms of solid content, preferably 50% by weight to 99.9% by weight, more preferably 60% by weight to 99.9% by weight, even more preferably 70% by weight to 99.9% by weight, and particularly preferably 80% by weight to 99.9% by weight.

[0034] The weight average molecular weight of the acrylic resin is preferably 300,000 to 2,500,000, more preferably 350,000 to 2,000,000, and even more preferably 400,000 to 1,500,000, in order to further exert the effects of the present invention.

[0035] As the acrylic resin, any appropriate acrylic resin can be adopted as long as it does not impair the effects of the present invention. As the acrylic resin, from the viewpoint of being able to further exhibit the effects of the present invention, the following is preferable: (Component a) a (meth)acrylic acid alkyl ester in which the alkyl group in the alkyl ester moiety has 4 to 12 carbon atoms; (b) at least one selected from the group consisting of (meth)acrylic acid esters having an OH group and (meth)acrylic acid; (Component c) Vinyl ester monomer Examples of the acrylic resin include an acrylic resin formed by polymerization from a composition (A) containing the following:

[0036] The component a, the component b, and the component c may each independently be one type or two or more types.

[0037] Examples of component a include n-butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, and dodecyl (meth)acrylate. Among these, n-butyl (meth)acrylate and 2-ethylhexyl (meth)acrylate are preferred, and 2-ethylhexyl acrylate is more preferred, in terms of being able to further exhibit the effects of the present invention.

[0038] Examples of component b include (meth)acrylic acid and (meth)acrylic acid esters having an OH group, such as hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, and hydroxybutyl (meth)acrylate. Among these, in terms of being able to further exhibit the effects of the present invention, preferred are hydroxyethyl (meth)acrylate and (meth)acrylic acid, more preferred are hydroxyethyl acrylate and acrylic acid, and even more preferred is acrylic acid.

[0039] Examples of component c include vinyl acetate, vinyl propionate, and vinyl laurate, with vinyl acetate being preferred in that it can further exert the effects of the present invention.

[0040] The composition (A) may contain a copolymerizable monomer (component d) other than components a, b, and c. The component d may be of only one type, or of two or more types.

[0041] Examples of the d component include (meth)acrylic acid alkyl esters in which the alkyl group in the alkyl ester moiety has 1 to 3 carbon atoms, such as methyl (meth)acrylate, ethyl (meth)acrylate, and propyl (meth)acrylate; carboxyl group-containing monomers (excluding (meth)acrylic acid) such as itaconic acid, maleic acid, fumaric acid, crotonic acid, isocrotonic acid, and acid anhydrides thereof (for example, acid anhydride group-containing monomers such as maleic anhydride and itaconic anhydride); (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N-methyl ( ... Amide group-containing monomers such as methyl (meth)acrylamide, N-methoxymethyl (meth)acrylamide, N-butoxymethyl (meth)acrylamide, and N-hydroxyethyl (meth)acrylamide; amino group-containing monomers such as aminoethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, and t-butylaminoethyl (meth)acrylate; epoxy group-containing monomers such as glycidyl (meth)acrylate and methylglycidyl (meth)acrylate; cyano group-containing monomers such as acrylonitrile and methacrylonitrile; N-vinyl Heterocycle-containing vinyl monomers such as N-vinyl-2-pyrrolidone, (meth)acryloylmorpholine, N-vinylpiperidone, N-vinylpiperazine, N-vinylpyrrole, N-vinylimidazole, vinylpyridine, vinylpyrimidine, and vinyloxazole; sulfonic acid group-containing monomers such as sodium vinyl sulfonate; phosphate group-containing monomers such as 2-hydroxyethyl acryloyl phosphate; imide group-containing monomers such as cyclohexylmaleimide and isopropylmaleimide; isocyanates such as 2-methacryloyloxyethyl isocyanate. Examples of suitable monomers include anate group-containing monomers; (meth)acrylic acid esters having an alicyclic hydrocarbon group such as cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, and isobornyl (meth)acrylate; (meth)acrylic acid esters having an aromatic hydrocarbon group such as phenyl (meth)acrylate, phenoxyethyl (meth)acrylate, and benzyl (meth)acrylate; olefins and dienes such as ethylene, butadiene, isoprene, and isobutylene; vinyl ethers such as vinyl alkyl ether; and vinyl chloride.

[0042] A polyfunctional monomer may also be used as component (d). A polyfunctional monomer refers to a monomer having two or more ethylenically unsaturated groups in one molecule. Any appropriate ethylenically unsaturated group may be used as the ethylenically unsaturated group as long as the effects of the present invention are not impaired. Examples of such ethylenically unsaturated groups include radically polymerizable functional groups such as vinyl groups, propenyl groups, isopropenyl groups, vinyl ether groups (vinyloxy groups), and allyl ether groups (allyloxy groups). Examples of polyfunctional monomers include hexanediol di(meth)acrylate, butanediol di(meth)acrylate, (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tri(meth)acrylate, allyl (meth)acrylate, vinyl (meth)acrylate, divinylbenzene, epoxy acrylate, polyester acrylate, and urethane acrylate.

[0043] As component d, (meth)acrylic acid alkoxyalkyl esters can also be used. Examples of (meth)acrylic acid alkoxyalkyl esters include 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, methoxytriethylene glycol (meth)acrylate, 3-methoxypropyl (meth)acrylate, 3-ethoxypropyl (meth)acrylate, 4-methoxybutyl (meth)acrylate, and 4-ethoxybutyl (meth)acrylate.

[0044] As component d, in terms of being able to further exert the effects of the present invention, preferred examples include (meth)acrylic acid alkyl esters in which the alkyl group in the alkyl ester moiety has 1 to 3 carbon atoms, such as methyl (meth)acrylate, ethyl (meth)acrylate, and propyl (meth)acrylate; and heterocycle-containing vinyl monomers such as N-vinyl-2-pyrrolidone, (meth)acryloylmorpholine, N-vinylpiperidone, N-vinylpiperazine, N-vinylpyrrole, N-vinylimidazole, vinylpyridine, vinylpyrimidine, and vinyloxazole.

[0045] The content of component a in the total amount of monomer components constituting the acrylic resin is preferably 25% by weight to 98% by weight, more preferably 35% by weight to 95% by weight, even more preferably 40% by weight to 80% by weight, particularly preferably 45% by weight to 70% by weight, and most preferably 50% by weight to 60% by weight, relative to the total amount of monomer components constituting the acrylic resin, in order to further exhibit the effects of the present invention.

[0046] The content of component b in the total amount of monomer components constituting the acrylic resin is preferably 1 to 40% by weight, more preferably 1 to 30% by weight, even more preferably 1.5 to 20% by weight, particularly preferably 2 to 15% by weight, and most preferably 2.5 to 10% by weight, relative to the total amount of monomer components constituting the acrylic resin, in order to further exhibit the effects of the present invention.

[0047] The content of component c in the total amount of monomer components constituting the acrylic resin is preferably 1 to 70% by weight, more preferably 10 to 65% by weight, even more preferably 20 to 60% by weight, particularly preferably 30 to 55% by weight, and most preferably 35 to 50% by weight, relative to the total amount of monomer components constituting the acrylic resin, in order to further exhibit the effects of the present invention.

[0048] The content of component d in the total amount of monomer components constituting the acrylic resin is preferably 0% by weight to 73% by weight, more preferably 0% by weight to 60% by weight, even more preferably 0% by weight to 50% by weight, particularly preferably 0% by weight to 40% by weight, and most preferably 0% by weight to 30% by weight, relative to the total amount of monomer components constituting the acrylic resin, in terms of being able to further exhibit the effects of the present invention.

[0049] Composition (A) may contain any appropriate other components as long as the effects of the present invention are not impaired. Examples of such other components include a polymerization initiator, a chain transfer agent, and a solvent. The content of these other components may be any appropriate content as long as the effects of the present invention are not impaired.

[0050] The polymerization initiator may be a thermal polymerization initiator, a photopolymerization initiator (photoinitiator), etc., depending on the type of polymerization reaction. Only one type of polymerization initiator may be used, or two or more types may be used.

[0051] A thermal polymerization initiator is preferably used when obtaining an acrylic resin by solution polymerization. Examples of such thermal polymerization initiators include azo polymerization initiators (e.g., 2,2'-azobisisobutyronitrile (hereinafter sometimes referred to as AIBN), 2,2'-azobis-2-methylbutyronitrile (hereinafter sometimes referred to as AMBN), 2,2'-azobis(2-methylpropionate)dimethyl, 4,4'-azobis-4-cyanovaleric acid), peroxide polymerization initiators (e.g., benzoyl peroxide), and redox polymerization initiators. Known thermal polymerization initiators can be used as these thermal polymerization initiators.

[0052] The photopolymerization initiator can be preferably used when obtaining an acrylic resin by active energy ray polymerization. Examples of the photopolymerization initiator include a benzoin ether-based photopolymerization initiator, an acetophenone-based photopolymerization initiator, an α-ketol-based photopolymerization initiator, an aromatic sulfonyl chloride-based photopolymerization initiator, a photoactive oxime-based photopolymerization initiator, a benzoin-based photopolymerization initiator, a benzyl-based photopolymerization initiator, a benzophenone-based photopolymerization initiator, a ketal-based photopolymerization initiator, and a thioxanthone-based photopolymerization initiator. Known photopolymerization initiators can be used as these photopolymerization initiators.

[0053] The amount of the polymerization initiator used may be any appropriate amount as long as it does not impair the effects of the present invention. The amount of the polymerization initiator used is, for example, preferably 0.01 to 15 parts by weight, more preferably 0.05 to 10 parts by weight, even more preferably 0.08 to 5 parts by weight, and particularly preferably 0.1 to 3 parts by weight, relative to 100 parts by weight of the total amount of the monomer components constituting the acrylic resin.

[0054] As the chain transfer agent, known chain transfer agents can be used, and the chain transfer agent may be one kind or two or more kinds.

[0055] The amount of the chain transfer agent used may be any appropriate amount as long as it does not impair the effects of the present invention, and is, for example, preferably 0.01 to 15 parts by weight per 100 parts by weight of the total amount of the monomer components constituting the acrylic resin.

[0056] Any appropriate solvent can be used as the solvent as long as it does not impair the effects of the present invention. Examples of such solvents include organic solvents such as esters such as ethyl acetate and n-butyl acetate; aromatic hydrocarbons such as toluene and benzene; aliphatic hydrocarbons such as n-hexane and n-heptane; alicyclic hydrocarbons such as cyclohexane and methylcyclohexane; and ketones such as methyl ethyl ketone and methyl isobutyl ketone. Only one type of solvent may be used, or two or more types may be used.

[0057] The amount of the solvent used may be any appropriate amount within a range that does not impair the effects of the present invention.

[0058] The acrylic resin can be produced by any appropriate polymerization method as long as the effects of the present invention are not impaired. Examples of polymerization methods that can be used to polymerize the acrylic resin include solution polymerization, emulsion polymerization, bulk polymerization, and active energy ray polymerization by irradiation with ultraviolet rays or the like. Typical examples are solution polymerization and active energy ray polymerization, and solution polymerization is preferred.

[0059] As a method for supplying monomers when carrying out solution polymerization, a batch charging method in which the entire amount of the monomer components is supplied at once, a continuous supply (dropping) method, a divided supply (dropping) method, or the like can be appropriately adopted.

[0060] The temperature for solution polymerization can be appropriately selected depending on the types of monomers and solvents used, the type of polymerization initiator, etc., and is preferably 20° C. to 160° C., more preferably 30° C. to 140° C., even more preferably 40° C. to 120° C., and particularly preferably 50° C. to 100° C. The time for solution polymerization can be appropriately selected depending on the types of monomers and solvents used, the type of polymerization initiator, etc., and is preferably 1 hour to 24 hours, more preferably 1 hour to 12 hours.

[0061] In the solution polymerization, it is preferable to carry out the reaction at temperature T1 for X hours, and then further hold the reaction at temperature T2 (where T2>T1) for Y hours, in order to further exert the effects of the present invention.

[0062] T1 is preferably less than 90°C, more preferably less than 85°C, even more preferably less than 80°C, particularly preferably less than 75°C, and most preferably less than 70°C.

[0063] T2 only needs to satisfy T2>T1, preferably T2-T1>1°C, more preferably T2-T1>5°C, even more preferably T2-T1>10°C, even more preferably T2-T1>15°C, particularly preferably T2-T1>20°C, and most preferably T2-T1>25°C.

[0064] X is preferably 0.1 to 48, more preferably 1 to 24, further preferably 1 to 12, and particularly preferably 1 to 10.

[0065] Y is preferably 0.1 to 48, more preferably 1 to 24, even more preferably 2 to 24, still more preferably 3 to 24, particularly preferably 4 to 24, and most preferably 5 to 24.

[0066] <1-1-b. Crosslinking agents> The acrylic pressure-sensitive adhesive composition may contain a crosslinking agent. Use of the crosslinking agent can further enhance the effects of the present invention. The crosslinking agent may be one type only, or two or more types.

[0067] Examples of crosslinking agents include polyfunctional isocyanate-based crosslinking agents, epoxy-based crosslinking agents, melamine-based crosslinking agents, peroxide-based crosslinking agents, as well as urea-based crosslinking agents, metal alkoxide-based crosslinking agents, metal chelate-based crosslinking agents, metal salt-based crosslinking agents, carbodiimide-based crosslinking agents, oxazoline-based crosslinking agents, aziridine-based crosslinking agents, and amine-based crosslinking agents. Among these, at least one selected from the group consisting of polyfunctional isocyanate-based crosslinking agents and epoxy-based crosslinking agents is preferred in terms of further exhibiting the effects of the present invention.

[0068] As the polyfunctional isocyanate-based crosslinking agent, a compound having two or more isocyanate groups (including isocyanate-regenerating polar groups in which the isocyanate group is temporarily protected by a blocking agent or oligomerization, etc.) in one molecule can be used. Specific examples of the polyfunctional isocyanate crosslinking agent include lower aliphatic polyisocyanates such as butylene diisocyanate and hexamethylene diisocyanate; alicyclic isocyanates such as cyclopentylene diisocyanate, cyclohexylene diisocyanate and isophorone diisocyanate; aromatic diisocyanates such as 2,4-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, xylylene diisocyanate and polymethylene polyphenyl isocyanate; trimethylolpropane / tolylene diisocyanate trimer adduct (for example, manufactured by Tosoh Corporation, trade name: Coronate L), trimethylolpropane / hexamethylene diisocyanate trimer adduct (for example, manufactured by Tosoh Corporation, trade name: Coronate HL), and isocyanurate of hexamethylene diisocyanate (for example, manufactured by Tosoh Corporation, trade name: Coronate HL). Examples of suitable polyisocyanates include isocyanate adducts such as those manufactured by Saw Chemicals under the trade name of Coronate HX; trimethylolpropane adducts of xylylene diisocyanate (for example, Mitsui Chemicals under the trade name of Takenate D110N), trimethylolpropane adducts of xylylene diisocyanate (for example, Mitsui Chemicals under the trade name of Takenate D120N), trimethylolpropane adducts of isophorone diisocyanate (for example, Mitsui Chemicals under the trade name of Takenate D140N), and trimethylolpropane adducts of hexamethylene diisocyanate (for example, Mitsui Chemicals under the trade name of Takenate D160N); polyether polyisocyanates, polyester polyisocyanates, and adducts of these with various polyols; and polyisocyanates multifunctionalized with isocyanurate bonds, biuret bonds, allophanate bonds, etc.

[0069] Examples of epoxy crosslinking agents (polyfunctional epoxy compounds) include N,N,N',N'-tetraglycidyl-m-xylylenediamine, diglycidylaniline, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, 1,6-hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, sorbitol polyglycidyl ether, and methyl ... Examples of epoxy crosslinking agents include diglycidyl ether, glycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, polyglycerol polyglycidyl ether, sorbitan polyglycidyl ether, trimethylolpropane polyglycidyl ether, adipic acid diglycidyl ester, o-phthalic acid diglycidyl ester, triglycidyl-tris(2-hydroxyethyl)isocyanurate, resorcinol diglycidyl ether, and bisphenol-S-diglycidyl ether, as well as epoxy resins having two or more epoxy groups in the molecule. Examples of epoxy crosslinking agents include commercially available products such as "Tetrad C" (manufactured by Mitsubishi Gas Chemical Company, Inc.).

[0070] The content of the crosslinking agent in the acrylic pressure-sensitive adhesive composition may be any appropriate content within the range that does not impair the effects of the present invention. In order to further exhibit the effects of the present invention, the content is preferably 0.001 to 30 parts by weight, more preferably 0.01 to 20 parts by weight, even more preferably 0.1 to 15 parts by weight, particularly preferably 1 to 15 parts by weight, and most preferably 1.5 to 15 parts by weight, relative to the solid content (100 parts by weight) of the acrylic resin as the base polymer.

[0071] <1-1-c. Solvents> The acrylic pressure-sensitive adhesive composition may contain a solvent. Any appropriate solvent may be used as the solvent as long as it does not impair the effects of the present invention. Examples of such solvents include organic solvents such as esters such as ethyl acetate and n-butyl acetate; aromatic hydrocarbons such as toluene and benzene; aliphatic hydrocarbons such as n-hexane and n-heptane; alicyclic hydrocarbons such as cyclohexane and methylcyclohexane; and ketones such as methyl ethyl ketone and methyl isobutyl ketone. The solvent may be one type only, or two or more types may be used.

[0072] The content of the solvent may be any appropriate amount within a range that does not impair the effects of the present invention.

[0073] <1-1-d. Other ingredients> The acrylic pressure-sensitive adhesive composition may contain any other appropriate components as long as they do not impair the effects of the present invention. Examples of such other components include other polymer components, oligomer components, crosslinking accelerators, crosslinking retarders, catalysts, crosslinking catalysts, silane coupling agents, tackifying resins (rosin derivatives, polyterpene resins, petroleum resins, oil-soluble phenols, etc.), fatty acid esters, silicone additives, antioxidants, inorganic fillers, organic fillers, metal powders, colorants (pigments, dyes, etc.), foil-like materials, UV absorbers, antioxidants, light stabilizers, plasticizers, softeners, surfactants, antistatic agents, conductive agents, stabilizers, surface lubricants, leveling agents, corrosion inhibitors, heat stabilizers, polymerization inhibitors, and lubricants.

[0074] The content of other components in the acrylic pressure-sensitive adhesive composition is preferably 0 to 30 parts by weight, more preferably 0 to 20 parts by weight, and even more preferably 0 to 10 parts by weight, relative to 100 parts by weight of the acrylic resin as the base polymer.

[0075] ≪1-2. Base material layer≫ The surface protection film according to the embodiment of the present invention preferably includes a substrate layer.

[0076] The substrate layer may be one layer or two or more layers. The substrate layer is typically one layer. The substrate layer may be stretched.

[0077] The thickness of the substrate layer is preferably 4 μm to 450 μm, more preferably 8 μm to 400 μm, still more preferably 12 μm to 350 μm, and particularly preferably 16 μm to 250 μm.

[0078] For the surface of the base layer on which the pressure-sensitive adhesive layer is not applied, a release treatment can be performed by adding a fatty acid amide, polyethyleneimine, a long-chain alkyl additive, or the like to the base layer, or a coating layer made of any appropriate release agent such as a silicone-based, long-chain alkyl-based, or fluorine-based release agent can be provided, for example, in order to form a roll that is easy to unwind.

[0079] Any appropriate material can be used as the material for the substrate layer depending on the application. Examples include plastic, paper, metal film, nonwoven fabric, etc. Plastic is preferred. That is, the substrate layer is preferably a plastic film. The substrate layer may be made of one material or two or more materials. For example, it may be made of two or more plastics.

[0080] Examples of the plastics include polyester resins, polyamide resins, and polyolefin resins. Examples of polyester resins include polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate. Examples of polyolefin resins include homopolymers of olefin monomers and copolymers of olefin monomers. Specific examples of polyolefin resins include homopolypropylene; propylene copolymers such as block copolymers, random copolymers, and graft copolymers containing ethylene as a copolymerization component; reactor TPO; ethylene polymers such as low-density, high-density, linear low-density, and ultra-low-density copolymers; and ethylene copolymers such as ethylene-propylene copolymers, ethylene-vinyl acetate copolymers, ethylene-methyl acrylate copolymers, ethylene-ethyl acrylate copolymers, ethylene-butyl acrylate copolymers, ethylene-methacrylic acid copolymers, and ethylene-methyl methacrylate copolymers.

[0081] The substrate layer may contain any appropriate additives as needed. Examples of additives that may be contained in the substrate layer include antioxidants, ultraviolet absorbers, light stabilizers, antistatic agents, fillers, and pigments. The type, number, and amount of additives that may be contained in the substrate layer may be appropriately set depending on the purpose.

[0082] Examples of release liners include release liners in which the surface of a substrate (liner substrate) such as paper or plastic film is silicone-treated, and release liners in which the surface of a substrate (liner substrate) such as paper or plastic film is laminated with a polyolefin resin.

[0083] Examples of plastic films that can be used as liner substrates include polyethylene films, polypropylene films, polybutene films, polybutadiene films, polymethylpentene films, polyvinyl chloride films, vinyl chloride copolymer films, polyethylene terephthalate films, polybutylene terephthalate films, polyurethane films, and ethylene-vinyl acetate copolymer films.

[0084] The thickness of the release liner is preferably 1 μm to 500 μm, more preferably 3 μm to 450 μm, even more preferably 5 μm to 400 μm, and particularly preferably 10 μm to 300 μm.

[0085] ≪≪2. Optical and Electronic Devices≫≫ The surface protection film according to an embodiment of the present invention is typically attached to exposed surfaces of optical or electronic components to prevent scratches on the surfaces of the optical or electronic components during processing, assembly, inspection, transportation, etc. in the manufacturing process of optical or electronic devices, and can be suitably used for surface protection of optical or electronic components. The optical device according to an embodiment of the present invention includes a surface protection film according to an embodiment of the present invention. The electronic device according to an embodiment of the present invention includes a surface protection film according to an embodiment of the present invention. [Example]

[0086] The present invention will be specifically described below using examples, but the present invention is not limited to these examples. The test and evaluation methods used in the examples are as follows. The term "parts" means "parts by weight" unless otherwise specified, and the term "%" means "% by weight" unless otherwise specified.

[0087] <Measurement of loss tangent tanδ at a frequency of 0.001 Hz of the dynamic viscoelastic spectrum at 20°C> The adhesive composition used in the examples and comparative examples was applied to the silicone-treated surface of a release liner made of polyester resin with a thickness of 19 μm and one side of which had been silicone-treated, using a fountain roll so that the thickness after drying would be 15 μm, and the composition was dried at a drying temperature of 130°C for a drying time of 30 seconds to form an adhesive layer (A) on the release liner. Next, the silicone-treated side of a release liner made of polyester resin with a thickness of 19 μm and one side of which had been silicone-treated was bonded to the surface of the adhesive layer (A), and cured at 50°C for 48 hours to produce a laminate (1) consisting of release liner / adhesive layer (A) / release liner. Next, one release liner of the laminate (1) was peeled off, and the adhesive layer (A) side of another laminate (1) with one release liner peeled off was laminated onto the exposed adhesive layer (A), producing a laminate (2) with a release liner / adhesive layer (A) / adhesive layer (A) / release liner configuration. In the same manner, adhesive layers (A) were laminated until the total adhesive layer thickness was 1.0 mm or more. A die cut to a Φ8 mm size was then used with a jig, and the remaining release liner was removed to obtain a measurement sample. This measurement sample was placed on the probe of an analyzer (ARES-G2, manufactured by TA Instruments). Measurements were taken at frequencies from 0.1 Hz to 10 Hz at 10°C intervals from -50°C to 100°C at a strain of 0.05%. The measurement data was then swept using the WLF equation with the built-in analysis tool of the analyzer, with a reference temperature of 20°C. A master curve was then synthesized to obtain frequency-dependent data for the storage modulus and loss factor (tan δ). From the obtained data, the values of the storage modulus and loss factor (tan δ) at 0.001 Hz were extracted.

[0088] <Measurement of loss tangent tanδ at a frequency of 1 Hz of the dynamic viscoelastic spectrum at 20°C> A measurement sample was prepared in the same manner as in the measurement of the loss tangent tanδ of the dynamic viscoelasticity spectrum at a frequency of 0.001 Hz at 20° C., and this measurement sample was set on the probe of an analyzer (ARES-G2, manufactured by TA instruments). The temperature was raised from -50°C to 200°C at a rate of 5°C / min, and measurements were made at a frequency of 1 Hz under a strain of 0.05%. From the obtained data, the storage modulus and loss factor (tan δ) values at 20°C were extracted.

[0089] <Gel fraction of adhesive layer> A predetermined amount of adhesive sample (weight Wg1) taken from the adhesive layer was wrapped in a porous polytetrafluoroethylene membrane (weight Wg2) with an average pore size of 0.2 μm in a purse shape, and the opening was tied with string (weight Wg3). The porous polytetrafluoroethylene (PTFE) membrane used was available from Nitto Denko Corporation under the trade name "Nitoflon (registered trademark) NTF1122" (average pore size 0.2 μm, porosity 75%, thickness 85 μm) or an equivalent. The wrapped sample was immersed in a sufficient amount of ethyl acetate and kept at room temperature (23 °C) for 7 days to allow only the sol components of the adhesive to elute out of the membrane. After that, the wrapped sample was removed and the ethyl acetate adhering to the outer surface was wiped off. The wrapped sample was then dried at 130 °C for 2 hours, and the weight of the wrapped sample (Wg4) was measured. The gel fraction of the pressure-sensitive adhesive layer was calculated by the following formula. Gel fraction (%) = [(Wg4 - Wg2 - Wg3) / Wg1] x 100

[0090] <Evaluation of the number of bubbles generated after high-temperature, high-pressure treatment> The surface protection film was cut to a size of 70 mm wide x 70 mm long, the release liner was peeled off, and then the film was pressed with a hand roller onto the surface of the top coat layer side of an anti-glare film with an antifouling layer (produced in Production Example 1 described below) as an adherend, followed by lamination under pressure conditions of 0.25 MPa and 0.3 m / min, and the four sides from the surface protection film side were cut with a cutter to a width of 50 mm x length of 50 mm to obtain an evaluation sample. The film was then autoclaved for 15 minutes at 50°C and 5 atm, and then returned to room temperature and normal pressure. Immediately afterwards, the number of bubbles generated at the film edge was counted, and the number of bubbles generated was evaluated according to the following evaluation criteria (score): 5: No bubbles were observed (except for foreign matter bubbles). 4: Bubbles were observed on one or two of the edges. 3: Bubbles were observed on three of the edges. 2: Bubbles were observed on all edges. 1: Bubbles were observed all over the surface.

[0091] <Adhesion to acrylic board> The release liner was peeled off from the surface of a 25 mm wide x 100 mm long cut-out of the surface protection film, and the exposed adhesive layer was roll-bonded to an acrylic plate (Mitsubishi Chemical Corporation, trade name "Acrylite," thickness: 2 mm, width: 70 mm, length: 100 mm) at a pressure of 0.25 MPa and a feed rate of 0.3 m / min to prepare a test sample. The test sample was then left for 30 minutes at a temperature of 23°C and humidity of 50% RH. Then, under the same conditions, the test sample was placed in a tensile tester (Shimadzu Corporation, trade name "Autograph AG-Xplus HS 6000 mm / min High-Speed Model (AG-50NX plus)") and the load was measured when the surface protection film was peeled off from the acrylic plate at a tensile speed of 300 mm / min and a peel angle of 180°. The average load measured was recorded as the adhesive strength to the acrylic plate.

[0092] [Production Example 1]: Anti-glare film with anti-fouling layer (Preparation of Hard Coat Composition) As binder resins, 50 parts by weight of pentaerythritol polyacrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., trade name "Viscoat #300") and 50 parts by weight of urethane acrylate prepolymer (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "Shikou UV-1700TL") were used, 7.2 parts by weight of copolymer crosslinked particles of styrene and methyl methacrylate (MMA) (manufactured by Sekisui Plastics Co., Ltd., trade name "Techpolymer SSX-540TNR", average particle size 3.6 μm), 1.5 parts by weight of organic smectite (manufactured by Kunimine Industries Co., Ltd., trade name "Sumecton SAN") was used as a thixotropic agent, and 1.5 parts by weight of photopolymerization initiator (IGM A hard coat composition with a solids concentration of 50 wt% was prepared by mixing 3 parts by weight of a resin (manufactured by Kyoeisha Chemical Co., Ltd., product name "OMNIRAD907") and 0.15 parts by weight of a leveling agent (manufactured by Kyoeisha Chemical Co., Ltd., product name "POLYFLOW LE303") and diluting with a toluene / cyclopentanone mixed solvent (weight ratio 70 / 30). The above blending amounts are the amount of solids (non-volatile content), and the organically modified smectite was diluted with toluene to a solids content of 6 wt%. (Hard coat film manufacturing) The hard coat composition obtained above was applied to an 80 μm-thick triacetyl cellulose (TAC) film (manufactured by Konica Minolta Opto, Inc., product name "KC8UA") using a Comma Coater (registered trademark), and heated at 80°C for 1 minute. Thereafter, the hard coat composition was applied to a high-pressure mercury lamp with an integrated light dose of 300 mJ / cm. 2 The coating layer was cured by irradiation with ultraviolet light of 1000 kJ / cm, thereby obtaining a hard-coated film having an antiglare hard-coating layer with a thickness of 6.0 μm on the TAC film. (Manufacturing of optical adjustment layer) The hard-coated film obtained above was introduced into a roll-to-toll sputtering system, and while the film was running, the hard-coat layer was bombarded (plasma treatment with Ar gas), after which a 100 nm thick SiO2 layer was sputtered. A Si target was used to deposit the SiO2 layer, and the amount of oxygen introduced was adjusted using plasma emission monitoring (PEM) control to maintain the deposition mode in the transition region. (Formation of antifouling layer) A fluorine-based resin solution containing a perfluoroether with -(O-CF(CF3)-CF2)- in the main chain skeleton was applied to the surface SiO2 layer of the optical adjustment layer so that the thickness after drying would be 10 nm, forming an antifouling layer as a top coat layer.

[0093] [Production Example 2]: Production of acrylic copolymer (1) A four-neck flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a condenser was charged with 100 parts by weight of 2-ethylhexyl acrylate (2EHA) (manufactured by Nippon Shokubai Co., Ltd.), 80 parts by weight of vinyl acetate (VAc) (manufactured by Showa Denko K.K.), 5 parts by weight of acrylic acid (AA) (manufactured by Nippon Shokubai Co., Ltd.), 0.3 parts by weight of Niper BW (manufactured by NOF Corp.), and 2,400 parts by weight of toluene. Nitrogen gas was introduced while gently stirring, and the liquid temperature in the flask was maintained at around 65 ° C. for 6 hours to carry out a polymerization reaction. The liquid temperature in the flask was then raised to 95 ° C. and maintained for 8 hours, after which it was cooled to obtain a solution of acrylic copolymer (1) with a weight average molecular weight of 470,000 (solid content: 38 wt%).

[0094] [Production Example 3]: Production of acrylic copolymer (2) A four-neck flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a condenser was charged with 100 parts by weight of 2-ethylhexyl acrylate (2EHA) (manufactured by Nippon Shokubai Co., Ltd.), 80 parts by weight of vinyl acetate (VAc) (manufactured by Showa Denko K.K.), 5 parts by weight of acrylic acid (AA) (manufactured by Nippon Shokubai Co., Ltd.), 0.3 parts by weight of Niper BW (manufactured by NOF Corp.), and 2,400 parts by weight of toluene. Nitrogen gas was introduced while gently stirring, and the liquid temperature in the flask was maintained at around 65 ° C. for 6 hours to carry out a polymerization reaction. After cooling, a solution of acrylic copolymer (2) with a weight-average molecular weight of 470,000 (solid content: 38 wt%) was obtained.

[0095] [Example 1]: Production of surface protective film (1) To the solution of acrylic copolymer (1) obtained in Production Example 2, 6 parts by weight of TETRAD-C (manufactured by Mitsubishi Gas Chemical Co., Ltd.) was added as a crosslinking agent per 100 parts by weight of the solid content, and the mixture was diluted with methyl ethyl ketone so that the total solid content was 20% by weight, and stirred with a disperser to obtain adhesive composition (1). The obtained pressure-sensitive adhesive composition (1) was applied to a polyester resin substrate "Lumirror S10" (thickness 38 μm, manufactured by Toray Industries, Inc.) using a fountain roll so that the thickness after drying would be 15 μm, and the coating was dried at a drying temperature of 130°C for 30 seconds to form a pressure-sensitive adhesive layer (1) on the substrate. Next, the silicone-treated side of a release liner made of polyester resin and having a thickness of 19 μm, one side of which had been silicone-treated, was attached to the surface of the pressure-sensitive adhesive layer (1), and the resulting mixture was cured at 50°C for 48 hours to obtain a surface protection film (1) having a configuration of release liner / pressure-sensitive adhesive layer (1) / substrate layer. The results are shown in Table 1.

[0096] [Examples 2 to 5]: Production of surface protection films (2) to (5) The same procedure as in Example 1 was carried out except that the amount of crosslinking agent was changed as shown in Table 1, to obtain pressure-sensitive adhesive compositions (2) to (5) and surface protection films (2) to (5). The results are shown in Table 1.

[0097] [Example 6]: Production of surface protective film (6) The same procedure as in Example 1 was carried out except that the amount of crosslinking agent and the thickness of the adhesive layer were changed as shown in Table 1, to obtain an adhesive composition (6) and a surface protection film (6). The results are shown in Table 1.

[0098] [Example 7]: Production of surface protective film (7) The same procedure as in Example 1 was carried out except that the amount of crosslinking agent and the thickness of the adhesive layer were changed as shown in Table 1, to obtain an adhesive composition (7) and a surface protection film (7). The results are shown in Table 1.

[0099] [Comparative Example 1]: Production of Surface Protection Film (C1) The procedure of Example 1 was repeated except that the solution of acrylic copolymer (2) obtained in Production Example 3 was used instead of the solution of acrylic copolymer (1) obtained in Production Example 2, and the amount of crosslinking agent was changed as shown in Table 1, to obtain a pressure-sensitive adhesive composition (C1) and a surface protection film (C1). The results are shown in Table 1.

[0100] [Table 1]

[0101] [Example 8] The release liner was peeled off from each of the surface protection films (1) to (7) obtained in Examples 1 to 7, and the pressure-sensitive adhesive layer side was attached to a polarizing plate (manufactured by Nitto Denko Corporation, product name "TEG1465DUHC"), which is an optical component, to obtain an optical device.

[0102] [Example 9] The release liner was peeled off from each of the surface protection films (1) to (7) obtained in Examples 1 to 7, and the adhesive layer side was attached to a conductive film (manufactured by Nitto Denko Corporation, product name "ELECRYSTA V270L-TFMP"), which is an electronic component, to obtain an electronic device. [Industrial Applicability]

[0103] The surface protection film of the present invention can be used for any suitable purpose, such as preventing scratches on the surfaces of optical or electronic components during processing, assembly, inspection, transportation, etc. in the manufacturing process of optical or electronic devices. [Explanation of symbols]

[0104] 10 Release liner 20 adhesive layer 30 Base material layer 100 adhesive films

Claims

1. A surface protection film including a pressure-sensitive adhesive layer, the pressure-sensitive adhesive layer has a loss tangent at 20°C of a dynamic viscoelasticity spectrum at a frequency of 0.001 Hz of 0.07 or more; Surface protection film.

2. The surface protection film according to claim 1 , wherein the pressure-sensitive adhesive layer has a gel fraction of 70% or more.

3. The surface protection film according to claim 1, wherein the pressure-sensitive adhesive layer has a thickness of 0.5 μm to 100 μm.

4. 2. The surface protection film according to claim 1, wherein the adhesive layer is attached to the surface of an acrylic plate, left for 30 minutes in an environment of a temperature of 23°C and a humidity of 50% RH, and then the surface protection film is peeled from the surface of the acrylic plate at a peel angle of 180 degrees and a peel speed of 300 mm / min in an environment of a temperature of 23°C and a humidity of 50% RH, and the adhesive strength is 0.5 N / 25 mm or less.

5. An optical device comprising the surface protection film according to any one of claims 1 to 4.

6. An electronic device comprising the surface protection film according to any one of claims 1 to 4.

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