Protective film and laminate

Abstract

The present disclosure provides a protective film which comprises a resin base material and a surface protective layer that is disposed on one surface of the resin base material. The surface protective layer contains a cured product of at least one of an ionizing radiation-curable resin and a thermosetting resin, has a thickness of 3.0-15 μm inclusive, and has a nanoindentation hardness of 100-350 MPa inclusive.

Description

Protective films and laminates

[0001] The present disclosure relates to protective films and laminates.

[0002] Resin films that are laminated onto various adherends to protect the adherends have been known. Such resin films are also called overlay films. For example, Patent Document 1 discloses an acrylic film containing a specific ultraviolet absorber. Patent Document 2 discloses a protective film including a transparent polyolefin resin layer containing a specific light stabilizer and a transparent olefin resin.

[0003] JP 2015-206024 A JP 2023-029433 A

[0004] Protective films are required to have good surface properties such as solvent resistance and scratch resistance. However, resin substrates such as acrylic films and olefin films have poor surface properties such as solvent resistance and scratch resistance. It has been proposed to improve the surface properties by forming a coating layer containing a fluororesin on the surface of the resin substrate, but there is room for improvement in solvent resistance and scratch resistance. Furthermore, from the viewpoint of reducing the impact on the human body and the environment, it is preferable that the protective film does not contain an organic fluorine compound.

[0005] Therefore, the inventors of the present application have investigated disposing a surface protective layer containing a cured product of at least one of an ionizing radiation curable resin and a thermosetting resin on the surface of a resin substrate in order to improve solvent resistance and abrasion resistance. However, when a protective film having a surface protective layer containing a cured product of an ionizing radiation curable resin or a thermosetting resin is laminated on the corners of an adherend, it may have poor bending suitability, such as whitening and cracking at the bent portion.

[0006] The present disclosure has been made in view of the above circumstances, and has as its main object to provide a protective film that has excellent solvent resistance and scratch resistance, and also has good bending suitability.

[0007] The present disclosure provides a protective film having a resin substrate and a surface protective layer disposed on one side of the resin substrate, wherein the surface protective layer contains a cured product of at least one of an ionizing radiation curable resin and a thermosetting resin, the thickness of the surface protective layer is 3.0 μm or more and 15 μm or less, and the nanoindentation hardness of the surface protective layer is 100 MPa or more and 350 MPa or less.

[0008] The present disclosure provides a laminate having an adherend and the above-described protective film.

[0009] The present disclosure has the effect of providing a protective film that is excellent in solvent resistance and scratch resistance, and also has good bending suitability.

[0010] Fig. 1 is a schematic cross-sectional view illustrating a protective film according to the present disclosure. Fig. 2 is a schematic cross-sectional view illustrating a laminate according to the present disclosure. Fig. 3 is a view illustrating a bending aptitude test in Examples.

[0011] Below, embodiments will be described with reference to the drawings etc. However, the present disclosure can be implemented in many different forms and is not limited to the description of the embodiments exemplified below. Furthermore, to clarify the explanation, the drawings may show the width, thickness, and shape of each part schematically compared to the actual form, but this is merely an example and should not be construed as limiting.

[0012] In this specification, when describing a mode in which another component is placed on a certain component, the terms "above" or "below" include both a case in which another component is placed directly above or below the certain component so as to be in contact with the component, and a case in which another component is placed above or below the certain component with another component interposed therebetween, unless otherwise specified. Also, in this specification, when describing a mode in which another component is placed on the surface of a certain component, the terms "on the surface" or "on the surface side" include both a case in which another component is placed directly above or below the certain component so as to be in contact with the component, and a case in which another component is placed above or below the certain component with another component interposed therebetween, unless otherwise specified.

[0013] In addition, in this specification, the terms "sheet" and "film" are not distinguished from each other solely based on the difference in name. For example, "sheet" also includes a member called "film."

[0014] The protective film and laminate according to the present disclosure will be described in detail below.

[0015] A. Protective Film FIGS. 1, 2(a), and 2(b) are schematic cross-sectional views illustrating protective films according to the present disclosure. The protective film 10 shown in FIG. 1 includes a resin substrate 1 and a surface protective layer 2 disposed on one side of the resin substrate 1. As shown in FIG. 2(a), the protective film 10 may include an adhesive layer 3 on the side of the resin substrate 1 opposite the surface protective layer 2. Although not specifically shown, the protective film 10 may include a heat seal layer or a back primer layer instead of the adhesive layer 3. As shown in FIG. 2(b), the protective film 10 may include a primer layer 4 between the resin substrate 1 and the surface protective layer 2.

[0016] In the present disclosure, the surface protection layer 2 contains a cured product of at least one of an ionizing radiation curable resin and a thermosetting resin, the thickness of the surface protection layer 2 is within a predetermined range, and the nanoindentation hardness of the surface of the surface protection layer 2 is within a predetermined range.

[0017] According to the present disclosure, the surface protective layer contains a cured product of at least one of an ionizing radiation curable resin and a thermosetting resin, and the thickness of the surface protective layer is equal to or greater than a predetermined value, and the nanoindentation hardness of the surface of the surface protective layer is equal to or greater than a predetermined value, thereby achieving good solvent resistance and scratch resistance. On the other hand, the thickness of the surface protective layer is equal to or less than a predetermined value, and the nanoindentation hardness of the surface protective layer is equal to or less than a predetermined value, thereby achieving good bending suitability when laminated on an adherend. In other words, the occurrence of whitening and cracking in the bent portion of the protective film can be suppressed.

[0018] Furthermore, the surface protective layer containing a cured product of at least one of an ionizing radiation curable resin and a thermosetting resin does not usually contain an organic fluorine compound, and therefore can reduce the impact on the human body and the environment.

[0019] 1. Surface Protective Layer The surface protective layer is disposed on one surface of the resin substrate. The surface protective layer protects the resin substrate. The surface protective layer contributes to improving the surface properties (solvent resistance and scratch resistance) of the laminate. The surface protective layer and the resin substrate may be disposed so as to be in direct contact with each other, or may be disposed via another layer.

[0020] (1) The material surface protective layer contains a cured product of at least one of an ionizing radiation curable resin and a thermosetting resin. That is, the surface protective layer contains a cured product of an ionizing radiation curable resin, a thermosetting resin, or both. In particular, the surface protective layer preferably contains a cured product of an ionizing radiation curable resin. This is because ionizing radiation curable resins tend to have a higher crosslink density than thermosetting resins, and a surface protective layer with higher solvent resistance and scratch resistance can be obtained.

[0021] An ionizing radiation-curable resin is a composition containing a compound (ionizing radiation-curable compound) having an ionizing radiation-curable functional group, and is cured by ionizing radiation. Ionizing radiation refers to electromagnetic waves or charged particle beams that have an energy quantum capable of polymerizing or crosslinking molecules. Typically, ultraviolet (UV) or electron beams (EB) are used as ionizing radiation, but other types of radiation, such as electromagnetic waves (e.g., X-rays and γ-rays), α-rays, and charged particle beams (e.g., ion beams), may also be used. The ionizing radiation-curable resin may be either an ultraviolet-curable resin or an electron beam-curable resin. Electron beam-curable resins have the advantages of less odor due to the absence of a polymerization initiator, and are less likely to be discolored. Furthermore, electron beam-curable resins tend to have a higher crosslink density.

[0022] The ionizing radiation-curable functional group is a group that crosslinks and cures upon irradiation with ionizing radiation, and examples thereof include functional groups having an ethylenic double bond, such as a (meth)acryloyl group, a vinyl group, and an allyl group. Other examples of the ionizing radiation-curable functional group include an epoxy group and an oxetanyl group. The (meth)acryloyl group refers to an acryloyl group or a methcroyl group. Furthermore, the (meth)acrylate refers to an acrylate or a methacrylate.

[0023] The ionizing radiation-curable compound is preferably a compound having two or more ethylenically unsaturated bond groups. In particular, the ionizing radiation-curable compound is preferably a polyfunctional (meth)acrylate compound having two or more ethylenically unsaturated bond groups. The polyfunctional (meth)acrylate compound may be a monomer or an oligomer.

[0024] Examples of bifunctional (meth)acrylate monomers include urethane acrylate, ethylene glycol di(meth)acrylate, bisphenol A tetraethoxydiacrylate, bisphenol A tetrapropoxydiacrylate, and 1,6-hexanediol diacrylate. On the other hand, examples of trifunctional or higher functional (meth)acrylate monomers include trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, dipentaerythritol tetra(meth)acrylate, and isocyanuric acid-modified tri(meth)acrylate.

[0025] Examples of polyfunctional (meth)acrylate oligomers include urethane (meth)acrylate, epoxy (meth)acrylate, polyester (meth)acrylate, and polyether (meth)acrylate. Urethane (meth)acrylate can be obtained, for example, by reacting a polyhydric alcohol and an organic diisocyanate with a hydroxy (meth)acrylate.

[0026] When the ionizing radiation curable resin is an ultraviolet ray curable resin, the ionizing radiation curable resin preferably contains additives such as a photopolymerization initiator and a photopolymerization accelerator. Examples of photopolymerization initiators include acetophenone, benzophenone, α-hydroxyalkylphenone, Michler's ketone, benzoin, benzyl dimethyl ketal, benzoyl benzoate, α-acyloxime ester, and thioxanthones. Examples of photopolymerization accelerators include p-dimethylaminobenzoic acid isoamyl ester and p-dimethylaminobenzoic acid ethyl ester.

[0027] In order to adjust the indentation hardness of the surface of the surface protective layer, the ionizing radiation-curable resin may further contain an acrylic polymer in addition to the ionizing radiation-curable compound. Examples of acrylic polymers include homopolymers of (meth)acrylic esters, copolymers of two or more different (meth)acrylic ester monomers, and copolymers of (meth)acrylic esters with other monomers. Specifically, (meth)acrylic resins composed of homopolymers or copolymers containing (meth)acrylic esters, such as polymethyl(meth)acrylate, polyethyl(meth)acrylate, polypropyl(meth)acrylate, polybutyl(meth)acrylate, methyl(meth)acrylate-butyl(meth)acrylate copolymers, ethyl(meth)acrylate-butyl(meth)acrylate copolymers, ethylene-methyl(meth)acrylate copolymers, and styrene-methyl(meth)acrylate copolymers, are preferably used.

[0028] The weight-average molecular weight of the acrylic polymer is, for example, about 10,000 to 150,000, and preferably about 10,000 to 40,000. In this specification, the weight-average molecular weight of the acrylic polymer is a value measured by gel permeation chromatography using polystyrene as a standard substance.

[0029] The content of the acrylic polymer in the ionizing radiation curable resin (composition containing an ionizing radiation curable compound) is, for example, 30% by mass or more, and may be 60% by mass or more. On the other hand, the content of the acrylic polymer is, for example, 90% by mass or less, and may be 80% by mass or less. By adjusting the content of the acrylic polymer, the indentation hardness of the surface of the surface protective layer can be adjusted.

[0030] A thermosetting resin is a resin that hardens when heated. Examples of thermosetting resins include (meth)acrylic resins, urethane resins, phenolic resins, urea melamine resins, epoxy resins, unsaturated polyester resins, and silicone resins. When a surface protective layer is formed using a resin composition containing a thermosetting resin, the resin composition may contain at least one of a curing agent and a curing catalyst, as necessary.

[0031] The surface protective layer may contain a matting agent. Examples of the matting agent include fillers. Examples of the filler include organic particles (organic beads) and inorganic particles (inorganic beads). Examples of materials for the organic particles include resins such as (meth)acrylic resins, urethane resins, silicone resins, and amide resins. On the other hand, examples of materials for the inorganic particles include inorganic materials such as silica, alumina, zirconia, titania (titanium dioxide), kaolinite, calcium carbonate, and barium sulfate. The content of the filler is, for example, 5 parts by mass or more and 70 parts by mass or less, or may be 10 parts by mass or more and 60 parts by mass or less, relative to 100 parts by mass of the resin constituting the surface protective layer.

[0032] The surface protective layer may contain a weatherproofing agent. The surface protective layer may contain at least one of an ultraviolet absorber and a light stabilizer as the weatherproofing agent. Examples of the ultraviolet absorber and light stabilizer include the same ultraviolet absorbers and light stabilizers as those described in "2. Resin substrate."

[0033] The surface protective layer may contain additives such as a silicone compound, a polymerization inhibitor, a crosslinking agent, an antistatic agent, an adhesion improver, an antioxidant, a leveling agent, a thixotropy-imparting agent, a coupling agent, a plasticizer, an antifouling agent, an antifoaming agent, a filler, and an anti-wear agent.

[0034] (2) Thickness The thickness of the surface protective layer is usually 3.0 μm or more, and may be 3.5 μm or more, 4.0 μm or more, 4.5 μm or more, or 5.0 μm or more. If the surface protective layer is thin, sufficient solvent resistance and scratch resistance may not be obtained. On the other hand, the thickness of the surface protective layer is usually 15 μm or less, and may be 12 μm or less, 10 μm or less, or 7.0 μm or less. If the surface protective layer is thick, bending suitability decreases. The thickness of the surface protective layer is determined by measuring the thickness at multiple locations from a cross-sectional image taken using a scanning electron microscope (SEM) and averaging the measured values. A large number of samples is preferably used, for example, 100 or more.

[0035] (3) Nanoindentation Hardness The nanoindentation hardness on the surface of the surface protection layer in the present disclosure is typically 100 MPa or more, and may be 120 MPa or more, or 150 MPa or more. If the nanoindentation hardness on the surface of the surface protection layer is low, good solvent resistance and scratch resistance may not be obtained. On the other hand, the nanoindentation hardness on the surface of the surface protection layer is typically 350 MPa or less, and may be 320 MPa or less. If the nanoindentation hardness on the surface of the surface protection layer is high, good bending suitability may not be obtained.

[0036] The nanoindentation hardness of the surface of the surface protective layer can be adjusted, for example, by the type, number of functional groups, molecular weight, etc. of the curable compound used to prepare the surface protective layer. For example, by reducing the number of functional groups of the ionizing radiation-curable compound, the number of crosslinking points in the cured product can be reduced, resulting in a more flexible structure and a tendency for the nanoindentation hardness to be lower. On the other hand, by increasing the number of functional groups of the ionizing radiation-curable compound, the number of crosslinking points in the cured product can be increased, resulting in a harder structure and a tendency for the nanoindentation hardness to be higher. Furthermore, for example, by reducing the molecular weight of the ionizing radiation-curable compound, the cured product can be made to have a harder structure and a tendency for the nanoindentation hardness to be higher. On the other hand, for example, by increasing the molecular weight of the ionizing radiation-curable compound, the cured product can be made to have a more flexible structure and a tendency for the nanoindentation hardness to be lower. Furthermore, when the surface protective layer contains a cured product of a thermosetting resin, the nanoindentation hardness can be adjusted by the type, content, etc. of the thermosetting resin and curing agent.

[0037] In this specification, "nanoindentation hardness" is measured by the nanoindentation method, which is a technique for calculating mechanical quantities from the load-displacement curve obtained by continuously measuring the load and displacement during the process of pressing an indenter into the surface of a sample and unloading it.

[0038] Specifically, the nanoindentation hardness of the surface of the surface protective layer is measured by vertically indenting a Berkovich indenter (material: diamond triangular pyramid) into the surface of the protective film (sample) opposite the resin substrate. First, a measurement sample is prepared by cutting the protective film in the thickness direction to a size of 15 mm to 25 mm square, and the surface of the sample facing the resin substrate is fixed to a glass slide with adhesive. The measurement device and measurement conditions are as follows. The nanoindentation hardness measurement is performed in an atmosphere with a temperature of 23±5°C and a humidity of 40 to 65%. The position where the Berkovich indenter is indented is determined by scanning the surface shape of the surface protective layer of the sample with the tip of the indenter and selecting a portion where the surface is smooth. When a filler is contained in the surface protective layer, a smooth portion of the surface protective layer is selected using the method described above, and the Berkovich indenter is indented into a position that avoids the location of the filler near the surface.

[0039] Measurement device: Nanoindenter (TI950 TriboIndenter, manufactured by BRUKER) Indenter used: Berkovich indenter (model number: TI-0039, manufactured by BRUKER) Push-in control method: Load control method Maximum push-in load: 250 μN Push-in rate: 10 μN / sec Load time: 10 seconds (pushing from 0 to 250 μN) Holding time: 5 seconds (constant at 250 μN) Unloading time: 10 seconds (returning from 250 μN to 0 μN) Number of measurements: 5

[0040] The nanoindentation hardness of the surface protective layer can be calculated as follows. First, the indentation depth h (nm) corresponding to the indentation load P (N) is continuously measured, and a load-displacement curve is created. The created load-displacement curve is analyzed, and the maximum indentation load Pmax (N) is calculated as the projected area A (mm ２ ) is divided by the indentation hardness H ＩＴ can be calculated (the following formula (1)): HIT=Pmax / A (1) Here, A is the contact projected area obtained by correcting the indenter tip shape using a standard sample of fused quartz in accordance with the standard method for the instrument.

[0041] In this specification, the indentation hardness of the surface of the surface protection layer is the arithmetic average of five measurements of the same sample, each measured at a different position. Each measurement is measured at a different position by at least 5 μm. During the measurement, it is preferable to use fused quartz, the standard sample of the equipment manufacturer, to confirm that the measurement is within ±5% of the reference value, in order to confirm that the indenter shape has been correctly corrected and that there are no problems with the operation and measurement of the equipment.

[0042] (4) 60° Gloss Value: The protective film of the present disclosure can exhibit a low gloss on the surface on the surface protective layer side. For example, the 60° gloss value of the surface on the surface protective layer side of the protective film is preferably 25.0 or less, more preferably 20.0 or less. When the 60° gloss value of the surface on the surface protective layer side of the protective film is within the above range, the adherend can be protected without impairing the texture of the adherend. Meanwhile, the 60° gloss value may be, for example, 5 or more, or 10 or more.

[0043] The 60° gloss value of the surface of the protective film on the surface protective layer side can be adjusted by the content of the matting agent in the surface protective layer.

[0044] In this specification, the 60° gloss value refers to the 60° specular gloss defined in "Method 3" of JIS Z8741:1997. The 60° gloss value is measured using a gloss meter. As the gloss meter, for example, a gloss meter GMX-203 (measurement angle 60°) manufactured by Murakami Color Research Laboratory Co., Ltd. may be used. The average of the measured values ​​at any 10 points on the surface of the surface protective layer side of the protective film is defined as the 60° gloss value of the surface of the surface protective layer side of the protective film.

[0045] 2. Resin Substrate The protective film according to the present disclosure has a resin substrate, which can increase the strength of the protective film.

[0046] Materials (a) Resin Examples of resins constituting the resin substrate include (meth)acrylic resin, polyolefin resin, polyester resin, polycarbonate resin, acrylonitrile-butadiene-styrene resin (hereinafter also referred to as "ABS resin"), and vinyl chloride resin. Among these, (meth)acrylic resin is preferred due to its excellent transparency and weather resistance. Examples of (meth)acrylic resin include polymethyl(meth)acrylate, polyethyl(meth)acrylate, polybutyl(meth)acrylate, and methyl(meth)acrylate-butyl(meth)acrylate copolymer, with polymethyl(meth)acrylate being preferred. The resins may be used alone or in combination of two or more.

[0047] (b) Weather Resistant The resin substrate preferably contains a weather resistant agent. When the resin substrate contains a weather resistant agent, the protective film has excellent weather resistance. Examples of weather resistant agents include an ultraviolet absorber and a light stabilizer. The resin substrate preferably contains at least one of an ultraviolet absorber and a light stabilizer. The resin substrate may contain one or more ultraviolet absorbers. Similarly, the resin substrate may contain one or more light stabilizers.

[0048] Examples of the ultraviolet absorber contained in the resin substrate include organic ultraviolet absorbers such as triazine-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, oxybenzophenone-based ultraviolet absorbers, salicylic acid ester-based ultraviolet absorbers, and cyano(meth)acrylate-based ultraviolet absorbers, and inorganic ultraviolet absorbers such as titanium dioxide, cerium oxide, and zinc oxide. Among these, triazine-based ultraviolet absorbers are more preferred because they are less likely to discolor and have higher weather resistance.

[0049] Examples of triazine-based ultraviolet absorbers include hydroxyphenyltriazine-based ultraviolet absorbers, such as 2-(2-hydroxy-4-[1-octyloxycarbonylethoxy]phenyl)-4,6-bis(4-phenylphenyl)-1,3,5-triazine, 2-[4-[(2-hydroxy-3-dodecyloxypropyl)oxy]-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, and 2,4-bis[2-hydroxy-4-butoxyphenyl]-6-(2,4-dibutoxyphenyl)-1,3,5-triazine. azine, 2-[4-[(2-hydroxy-3-tridecyloxypropyl)oxy]-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, 2-[4-[(2-hydroxy-3-(2'-ethyl)hexyl)oxy]-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, and 2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5[2-(2-ethylhexanoyloxy)ethoxy]phenol.

[0050] The content of the ultraviolet absorber contained in the resin substrate is, for example, 0.05 parts by mass or more and 10 parts by mass or less, or alternatively 0.5 parts by mass or more and 7 parts by mass or less, or 1.0 parts by mass or more and 5 parts by mass or less, relative to 100 parts by mass of the resin contained in the resin substrate. If the content of the ultraviolet absorber is high, bleeding out of the ultraviolet absorber may occur, and if the content of the ultraviolet absorber is low, sufficient ultraviolet absorption performance may not be obtained.

[0051] Examples of the light stabilizer contained in the resin substrate include hindered amine light stabilizers, such as 1,2,2,6,6-pentamethyl-4-piperidinyl methacrylate, bis(1,2,2,6,6-pentamethyl-4-piperidyl)sebacate, bis(2,2,6,6-pentamethyl-4-piperidyl)sebacate, bis(1,2,2,6,6-pentamethyl-4-piperidinyl)sebacate, methyl(1,2,2,6,6-pentamethyl-4-piperidinyl)sebacate, and 2,4-bis[N-butyl-N-(1-cyclohexyloxy-2,2,6,6-tetramethylpiperidin-4-yl)amino]-6-(2-hydroxyethylamine)-1,3,5-triazine).

[0052] The content of the light stabilizer contained in the resin substrate is, for example, 0.05 parts by mass or more and 10 parts by mass or less, or alternatively 0.5 parts by mass or more and 7 parts by mass or less, or 1.0 parts by mass or more and 5 parts by mass or less, relative to 100 parts by mass of the resin contained in the resin substrate. If the content of the light stabilizer is high, bleed-out of the light stabilizer may occur, and if the content of the light stabilizer is low, sufficient light stability may not be obtained.

[0053] (c) Rubber-Based Material The resin substrate preferably contains a rubber-based material in addition to the resins described above. The inclusion of a rubber-based material improves the bending property of the resin substrate. Examples of rubber-based materials include acrylic rubber, isoprene rubber, butadiene rubber, styrene-butadiene rubber, chloroprene rubber, acrylonitrile-butadiene rubber, butyl rubber, halogenated butyl rubber, urethane rubber, and polysulfide rubber. Among these, acrylic rubber is preferred. A single rubber-based material may be used, or two or more may be used in combination. When the resin substrate contains a (meth)acrylic resin, it is preferable to include acrylic rubber as the rubber-based material. This is because the bending property of the resin substrate is improved without impairing the transparency and weather resistance of the resin substrate. The acrylic rubber is, for example, a rubber obtained by polymerizing a mixture containing alkyl (meth)acrylate. The acrylic rubber may also be included in the form of a polymer with other polymerizable monomers (a polymer containing an acrylic rubber component).

[0054] When a resin and a rubber-based material are used in combination, the content of the rubber-based material contained in the resin substrate is not particularly limited, but it is preferable to adjust the amount so that the nanoindentation hardness on the surface of the resin substrate falls within the range described below.

[0055] The resin substrate may contain other additives depending on the type and application of the resin contained in the resin substrate. Examples of other additives include antioxidants, stabilizers, plasticizers, flame retardants, etc. Plasticizers are preferably added to improve the bending suitability of resin substrates that mainly contain vinyl chloride resin.

[0056] (2) Thickness The thickness of the resin substrate in the present disclosure is preferably 30 μm or more, and may be 50 μm or more. When the resin substrate contains a weathering agent, sufficient weather resistance can be obtained by having the thickness of the resin substrate in the above range. On the other hand, the thickness of the resin substrate is preferably 150 μm or less, and may be 100 μm or less. By having the thickness of the resin substrate in the above range, the protective film can be laminated to the adherend with good conformability.

[0057] (3) Nanoindentation Hardness The nanoindentation hardness on the surface of the resin substrate in the present disclosure is, for example, 50 MPa or more, and may be 100 MPa or more. When the nanoindentation hardness on the surface of the resin substrate is within the above range, the scratch resistance of the resin substrate itself and the processability when laminating an adherend are improved. For example, if the nanoindentation hardness on the surface of the resin substrate is low, the resin substrate may easily be creased, or the protective film may loosen during processing. On the other hand, the nanoindentation hardness on the surface of the resin substrate may be, for example, 250 MPa or less, and may be 200 MPa or less. When the nanoindentation hardness on the surface of the resin substrate is within the above range, the protective film can be laminated to the adherend with good conformability.

[0058] The nanoindentation hardness of the surface of a resin substrate can be adjusted by, for example, adjusting the content of the rubber-based material when the resin substrate (e.g., a resin substrate containing a (meth)acrylic resin) contains a rubber-based material. Specifically, the greater the content of the rubber-based material in the resin substrate, the lower the numerical value of the nanoindentation hardness of the surface of the resin substrate tends to be. Furthermore, when the resin substrate (e.g., a resin substrate containing a vinyl chloride resin) contains a plasticizer, the nanoindentation hardness can be adjusted by adjusting the content of the plasticizer. Specifically, the greater the content of the plasticizer, the lower the numerical value of the nanoindentation hardness of the surface of the resin substrate tends to be.

[0059] The nanoindentation hardness of the surface of the resin substrate is measured by removing the surface protective layer (and the primer layer, if present) from the protective film to expose the surface of the resin substrate. The measurement method and conditions are the same as those for measuring the nanoindentation hardness of the surface protective layer. The surface protective layer and primer layer can be removed by a flat milling method using an ion milling device. If a sample of the resin substrate before laminating the surface protective layer is available, the sample of the resin substrate may be measured directly.

[0060] (4) Other resin substrates are preferably transparent. The resin substrate may be colorless and transparent, or may be colored, transparent, or translucent. The total light transmittance of the resin substrate is preferably, for example, 85% or more, more preferably 88% or more, and even more preferably 90% or more. Such a high total light transmittance tends to improve the transparency of the protective film, resulting in good visibility of the adherend.

[0061] The total light transmittance of the resin substrate can be measured in accordance with JIS K7361-1:1999, for example, using a haze meter HM150 manufactured by Murakami Color Research Laboratory.

[0062] The method for producing the resin substrate is not particularly limited, and for example, a normal film production method such as extrusion film formation can be used.

[0063] 3. Primer Layer: The protective film according to the present disclosure preferably has a primer layer between the resin substrate and the surface protective layer. By providing the primer layer, the resin substrate can be protected together with the surface protective layer, further improving the surface properties of the protective film, such as scratch resistance, solvent resistance, and weather resistance. Furthermore, the interlayer adhesion between the resin substrate and the surface protective layer is improved.

[0064] The primer layer contains, for example, a resin component. Preferred examples of the resin component include acrylic resins, urethane resins, acrylic polyol resins, ester resins, amide resins, butyral resins, styrene resins, urethane-acrylic copolymers, polycarbonate-based urethane-acrylic copolymers (urethane-acrylic copolymers derived from polymers (polycarbonate polyols) having carbonate bonds in the polymer main chain and two or more hydroxyl groups at the terminals and side chains), vinyl chloride-vinyl acetate copolymer resins, vinyl chloride-vinyl acetate-acrylic copolymer resins, chlorinated propylene resins, nitrocellulose resins (nitrocellulose), and cellulose acetate resins. These can be used alone or in combination. Furthermore, the resin component may be a resin obtained by adding a curing agent such as an isocyanate-based curing agent or an epoxy-based curing agent to the resin and crosslinking and curing it. Among these, a polyol-based resin such as an acrylic polyol resin is preferably crosslinked and cured with an isocyanate-based curing agent, and an acrylic polyol resin is more preferably crosslinked and cured with an isocyanate-based curing agent.

[0065] The primer layer may contain a weather resistance agent. The primer layer may contain at least one of an ultraviolet absorber and a light stabilizer as the weather resistance agent. Examples of the ultraviolet absorber and light stabilizer include the same ultraviolet absorbers and light stabilizers as those described in "2. Resin substrate."

[0066] The thickness of the primer layer is preferably 2 μm or more, and may be 5 μm or more. When the thickness of the primer layer is in the above range, the surface properties of the protective film are further improved. On the other hand, the thickness of the primer layer is preferably 10 μm or less, and may be 7 μm or less. When the thickness of the primer layer is in the above range, the bending suitability of the protective film is further improved.

[0067] 4. Other Layers The protective film according to the present disclosure preferably has any one of a heat seal layer, an adhesive layer, and a back primer layer on the surface of the resin substrate opposite to the surface protective layer side, because the presence of any one of a heat seal layer, an adhesive layer, and a back primer layer improves adhesion between the adherend and the resin substrate.

[0068] (1) Heat Seal Layer The heat seal layer exhibits adhesiveness when heated. Examples of the resin contained in the heat seal layer include thermoplastic resins. Examples of thermoplastic resins include (meth)acrylic resins, polyacrylic polyols, urethane-based resins, vinyl chloride-based resins, vinyl acetate-based resins, vinyl chloride-vinyl acetate copolymer-based resins, styrene-acrylic copolymer-based resins, acrylic-vinyl acetate copolymer-based resins, polyester-based resins, amide-based resins, cyanoacrylate-based resins, and epoxy-based resins, which can be used alone or in combination.

[0069] The thickness of the heat seal layer is, for example, preferably 1 μm or more and 50 μm or less, and more preferably 5 μm or more and 30 μm or less.

[0070] (2) Adhesive Layer The adhesive layer contains an adhesive. Examples of adhesives constituting the adhesive layer include silicone resins and urethane resins. If necessary, the adhesive layer may contain a catalyst or the like for curing the adhesive.

[0071] The thickness of the adhesive layer is not particularly limited, but in order to obtain excellent adhesiveness, it is preferably 3 μm to 100 μm, more preferably 5 μm to 50 μm, and even more preferably 10 μm to 30 μm.

[0072] (3) Rear Primer Layer The material and thickness of the rear primer layer are the same as those of the primer layer described above.

[0073] 5. Protective Film (1) Total Light Transmittance The protective film is preferably transparent enough to allow the adherend to be visually recognized. The total light transmittance of the protective film obtained by laminating the above-described layers is, for example, preferably 80% or more, more preferably 85% or more, and even more preferably 90% or more. Such a high total light transmittance improves the visibility of the adherend.

[0074] The total light transmittance of the protective film can be measured in accordance with JIS K7361-1:1999, for example, using a haze meter HM150 manufactured by Murakami Color Research Laboratory.

[0075] (2) Thickness The thickness of the protective film in the present disclosure is not particularly limited, but is preferably 30 μm or more, more preferably 50 μm or more, and even more preferably 70 μm or more. When the thickness of the protective film is in the above range, handling is improved. On the other hand, the thickness of the protective film is preferably 150 μm or less, more preferably 120 μm or less, and even more preferably 100 μm or less. When the thickness of the protective film is in the above range, the protective film can be laminated to the adherend with good conformability.

[0076] (3) Uses The protective film according to the present disclosure can be used in various applications in which conventional protective films, overlay films, etc. are used. Specifically, the protective film can be used by being laminated on an adherend, which will be described later.

[0077] B. Laminate The laminate according to the present disclosure includes an adherend and the above-described protective film.

[0078] 3(a) and 3(b) are schematic cross-sectional views illustrating an example of a laminate according to the present disclosure. The laminate 100 shown in Fig. 3(a) and Fig. 3(b) includes an adherend 50 and the above-described protective film 10.

[0079] According to the present disclosure, by using the above-described protective film, a laminate having excellent solvent resistance, scratch resistance, and bending suitability can be obtained.

[0080] 1. Protective Film The protective film in the present disclosure is the same as that described above in "A. Protective Film," and therefore, a description thereof will be omitted here.

[0081] 2. Adherend The shape of the adherend is not particularly limited, and examples thereof include a sheet shape; a plate shape such as a flat plate or a curved plate; and a three-dimensional shape such as a cylinder or a polygonal prism. Here, a sheet shape refers to a shape having a thickness of 1000 μm or less, a plate shape refers to a shape having a thickness of more than 1000 μm and 10 mm or less, and a three-dimensional shape refers to a shape having a thickness of more than 10 mm.

[0082] The adherend may have a flat surface, a curved surface, or both a flat surface and a curved surface. The adherend may also have at least one of a corner, a protrusion, a recess, a ridge, a groove, a bellows portion, and a through-hole.

[0083] The adherend 50 in FIG. 3(a) is a substrate 51 made of various materials such as resin, glass, and wood.

[0084] The material of the substrate is not particularly limited. The substrate may be a resin member. Examples of resins used for the resin member include acrylic resin, polycarbonate resin, polyester resin, polystyrene resin, polyolefin resin such as polypropylene, ABS (acrylonitrile-butadiene-styrene copolymer) resin, phenol resin, vinyl chloride resin, cellulose resin, and rubber.

[0085] The substrate may be a wooden member. Examples of the wooden member include wood fiberboards. Examples of the wood fiberboard include wood veneers, wood plywood, laminated lumber, particle board, and MDF (medium density fiberboard). Examples of the material for the wooden member include wood such as cedar, cypress, pine, and lauan.

[0086] The substrate may be a metal member. Examples of metals used for the metal member include iron, aluminum, copper, and alloys containing one or more of these metals. The substrate may also be a ceramic member such as glass or porcelain, or a non-ceramic member such as gypsum, cement, ALC (lightweight aerated concrete), or calcium silicate.

[0087] The substrate may be pigmented or unpigmented.

[0088] As shown in Fig. 3(b), the adherend 50 may have a support layer 53 and a design layer 52 disposed on one surface of the support layer 53. The adherend 50 may have other layers disposed between the support layer 53 and the design layer 52, and on the surface of the design layer 52 opposite the support layer 53. The adherend 50 in Fig. 3(b) is, for example, a decorative sheet or a decorative sheet.

[0089] The design layer may be, for example, a colored layer, a patterned layer, or a metal layer. The design layer may also have both a colored layer and a patterned layer.

[0090] The colored layer may be a so-called solid colored layer disposed on the entire surface of the base layer. The colored layer may contain a binder resin and a colorant. The colored layer may be formed by a coating method.

[0091] The design (pattern) of the design layer is not particularly limited, and examples thereof include wood grain patterns such as tree rings and vessel grooves on the surface of a wooden board; stone grain patterns on the surface of stone slabs such as marble and granite; fabric grain patterns on the surface of fabric; leather grain patterns on the surface of leather; geometric patterns; letters; figures; and combinations thereof. The design layer contains, for example, a binder resin and a colorant. The design layer can be formed by a printing method.

[0092] The binder resin and colorant used in the colored layer and the design layer may be any known binder resin and colorant. If necessary, the colored layer and the design layer may contain additives such as ultraviolet absorbers, weathering agents such as light stabilizers, extender pigments, stabilizers, plasticizers, curing agents, and catalysts.

[0093] Examples of metal materials used for the metal layer include aluminum, chromium, tin, and indium. The metal layer can be formed by vapor deposition.

[0094] The thickness of the design layer is appropriately selected depending on the desired design and the type of design layer.

[0095] Examples of the constituent material of the support layer include the material of the resin member of the base described above.

[0096] The support layer may be colored or uncolored. The support layer may be a single layer or a laminate of two or more layers. In the latter case, the support layer may have two or more layers made of the same type of constituent material, or may have two or more layers made of different types of constituent material.

[0097] 3. Manufacturing Method of Laminate The laminate of the present disclosure can be obtained, for example, by laminating a protective film and an adherend. Specifically, the laminate is laminated so that the surface of the adherend (the surface that needs protection) faces the surface of the protective film facing the resin substrate.

[0098] The adherend is preferably subjected to a surface treatment such as corona treatment, polishing treatment, etc. as needed. Such a surface treatment can improve adhesion to the protective film.

[0099] When the protective film has a heat seal layer, a method of adhering the protective film to the adherend is to laminate the heat seal layer side of the protective film facing the adherend, and then apply heat above the melting point of the heat seal layer and apply pressure to adhere the protective film to the adherend.

[0100] When the protective film has an adhesive layer, the protective film can be adhered to the adherend by pressing the adhesive layer side of the protective film against the adherend.

[0101] When the protective film has a back primer layer, a method for adhering the protective film to the adherend is to apply pressure with an adhesive layer provided between the back primer layer of the protective film and the adherend, thereby adhering the protective film to the adherend.

[0102] 4. Laminate The laminate of the present disclosure has the above-mentioned protective film and adherend. The uses of the laminate of the present disclosure are not particularly limited, but examples thereof include: architectural components such as walls, ceilings, floors, roofs, eaves ceilings, fences, and gates; fittings or fixtures such as window frames, doors, handrails, baseboards, moldings, and window glass; general furniture such as chests of drawers, shelves, and desks; kitchen furniture such as dining tables and sinks; various types of furniture used in wet areas such as kitchens, toilets, bathrooms, and washbasins; surface decorative panels such as cabinets for home appliances and office equipment; interior or exterior components for automobiles; interior or exterior components for various types of vehicles other than automobiles, such as trains, airplanes, and ships; advertising stickers used for advertisements, signboards, shutters, windows, and the like; decorative stickers used for various types of vehicles such as automobiles and trains; display stickers used for traffic signs, guide boards, and the like. The laminate of the present disclosure may be a component used outdoors (exterior component) or a component used indoors (interior component), but is preferably an exterior component.

[0103] The present disclosure is not limited to the above-described embodiments. The above-described embodiments are merely examples, and anything that has substantially the same configuration as the technical idea described in the claims of the present disclosure and exhibits similar effects is included within the technical scope of the present disclosure.

[0104] Example 1 An acrylic film (ACRYPLEN HBS006H (manufactured by Mitsubishi Chemical Corporation, thickness 53 μm)) was prepared as a resin substrate. The nanoindentation hardness of the surface of the acrylic film was 160 MPa.

[0105] The following composition 1 for forming a surface protective layer was applied to one surface of a resin substrate by gravure printing and dried. It was then cured by irradiation with an electron beam (applied voltage: 120 kV, 5 Mrad) to form a surface protective layer with a thickness of 5.0 μm. (Composition 1 for forming a surface protective layer) Electron beam curable resin: 100 parts by mass (trifunctional urethane acrylate oligomer (weight average molecular weight 4000): 100 parts by mass) Solvent: appropriate amount

[0106] The following adhesive layer ink was applied by gravure printing to the surface of the resin substrate opposite the surface protective layer side. It was then dried at 120°C for 1 minute to form an adhesive layer with a thickness of 30 μm. (Adhesive layer ink) - Silicone resin adhesive (manufactured by Shin-Etsu Chemical Co., Ltd., product name "KR-3704"): 100 parts by mass - Platinum catalyst (manufactured by Shin-Etsu Chemical Co., Ltd., product name "CAT-PL-50T"): 0.5 parts by mass - Solvent (toluene): 100 parts by mass

[0107] In this way, a protective film having a surface protective layer, a resin substrate, and an adhesive layer in this order was obtained.

[0108] Example 2 The above-mentioned acrylic film (ACRYPLEN HBS006H (manufactured by Mitsubishi Chemical Corporation, thickness 53 μm)) was prepared as a resin substrate.

[0109] The following composition 2 for forming a surface protective layer was applied to one surface of a resin substrate by gravure printing and dried. It was then cured by irradiation with an electron beam (applied voltage: 120 kV, 5 Mrad) to form a surface protective layer with a thickness of 7.0 μm. (Composition 2 for forming a surface protective layer) Electron beam curable resin: 100 parts by mass (trifunctional urethane acrylate oligomer (weight average molecular weight 4000): 100 parts by mass) Solvent: appropriate amount

[0110] The adhesive layer ink was applied to the surface of the resin substrate opposite to the surface protective layer by gravure printing. The applied ink was then dried at 120°C for 1 minute to form an adhesive layer having a thickness of 30 µm. This resulted in a protective film having the surface protective layer, resin substrate, and adhesive layer in this order.

[0111] Example 3 The above-mentioned acrylic film (ACRYPLEN HBS006H (manufactured by Mitsubishi Chemical Corporation, thickness 53 μm)) was prepared as a resin substrate.

[0112] The following composition 3 for forming a surface protective layer was applied to one surface of a resin substrate by gravure printing and dried. It was then heated and cured to form a surface protective layer with a thickness of 5.0 μm. (Composition 3 for forming a surface protective layer) Thermosetting resin (acrylic polyol): 93 parts by mass Crosslinking agent (isocyanate): 7 parts by mass Solvent: appropriate amount

[0113] The adhesive layer ink was applied to the surface of the resin substrate opposite to the surface protective layer by gravure printing. The applied ink was then dried at 120°C for 1 minute to form an adhesive layer having a thickness of 30 µm. This resulted in a protective film having the surface protective layer, resin substrate, and adhesive layer in this order.

[0114] Example 4 The above-mentioned acrylic film (ACRYPLEN HBS006H (manufactured by Mitsubishi Chemical Corporation, thickness 53 μm)) was prepared as a resin substrate.

[0115] The following composition 4 for forming a surface protective layer was applied to one surface of a resin substrate by gravure printing and dried. It was then cured by irradiation with an electron beam (applied voltage: 120 kV, 5 Mrad) to form a surface protective layer with a thickness of 3.5 μm. Composition 4 for forming a surface protective layer was a combination of multiple electron beam curable compounds with different molecular weights. (Composition 4 for forming a surface protective layer) Electron beam curable resin: 100 parts by mass (Bifunctional urethane acrylate monomer (weight average molecular weight 600): 20 parts by mass) (Acrylic polymer (weight average molecular weight 12,000): 80 parts by mass) Solvent: appropriate amount

[0116] The adhesive layer ink was applied to the surface of the resin substrate opposite to the surface protective layer by gravure printing. The applied ink was then dried at 120°C for 1 minute to form an adhesive layer having a thickness of 30 µm. This resulted in a protective film having the surface protective layer, resin substrate, and adhesive layer in this order.

[0117] Comparative Example 1 The above-mentioned acrylic film (ACRYPLEN HBS006H (manufactured by Mitsubishi Chemical Corporation, thickness 53 μm)) was prepared as a resin substrate.

[0118] The following composition 5 for forming a surface protective layer was applied to one surface of a resin substrate by gravure printing and dried. It was then cured by irradiation with an electron beam (applied voltage: 120 kV, 5 Mrad) to form a surface protective layer with a thickness of 3.5 μm. Composition 5 for forming a surface protective layer was a combination of multiple electron beam curable compounds with different molecular weights. (Composition 5 for forming a surface protective layer) Electron beam curable resin: 100 parts by mass (Bifunctional urethane acrylate monomer (weight average molecular weight 600): 80 parts by mass) (Acrylic polymer (weight average molecular weight 12,000): 20 parts by mass) Solvent: appropriate amount

[0119] The adhesive layer ink was applied to the surface of the resin substrate opposite to the surface protective layer by gravure printing. The applied ink was then dried at 120°C for 1 minute to form an adhesive layer having a thickness of 30 µm. This resulted in a protective film having the surface protective layer, resin substrate, and adhesive layer in this order.

[0120] Comparative Example 2 The above-mentioned acrylic film (ACRYPLEN HBS006H (manufactured by Mitsubishi Chemical Corporation, thickness 53 μm)) was prepared as a resin substrate.

[0121] The following composition 6 for forming a surface protective layer was applied to one surface of a resin substrate by gravure printing and dried. It was then cured by irradiation with an electron beam (applied voltage: 120 kV, 5 Mrad) to form a surface protective layer with a thickness of 17.0 μm. (Composition 6 for forming a surface protective layer) Electron beam curable resin: 100 parts by mass (trifunctional urethane acrylate oligomer (weight average molecular weight 4000): 100 parts by mass) Solvent: appropriate amount

[0122] The adhesive layer ink was applied to the surface of the resin substrate opposite to the surface protective layer by gravure printing. The applied ink was then dried at 120°C for 1 minute to form an adhesive layer having a thickness of 30 µm. This resulted in a protective film having the surface protective layer, resin substrate, and adhesive layer in this order.

[0123] Comparative Example 3 The above-mentioned acrylic film (ACRYPLEN HBS006H (manufactured by Mitsubishi Chemical Corporation, thickness 53 μm)) was prepared as a resin substrate.

[0124] The following composition 7 for forming a surface protective layer was applied to one surface of a resin substrate by gravure printing and dried. It was then cured by irradiation with an electron beam (applied voltage: 120 kV, 5 Mrad) to form a surface protective layer with a thickness of 2.0 μm. Composition 7 for forming a surface protective layer was a combination of multiple electron beam curable compounds with different molecular weights. (Composition 7 for forming a surface protective layer) Electron beam curable resin: 100 parts by mass (Bifunctional urethane acrylate monomer (weight average molecular weight 600): 80 parts by mass) (Acrylic polymer (weight average molecular weight 12,000): 20 parts by mass) Solvent: appropriate amount

[0125] The adhesive layer ink was applied to the surface of the resin substrate opposite to the surface protective layer by gravure printing. The applied ink was then dried at 120°C for 1 minute to form an adhesive layer having a thickness of 30 µm. This resulted in a protective film having the surface protective layer, resin substrate, and adhesive layer in this order.

[0126] Comparative Example 4 The above-mentioned acrylic film (ACRYPLEN HBS006H (manufactured by Mitsubishi Chemical Corporation, thickness 53 μm)) was prepared as a resin substrate.

[0127] The following composition 8 for forming a surface protective layer was applied to one surface of a resin substrate by gravure printing and dried. The composition was then heated and cured to form a surface protective layer with a thickness of 2.0 μm. (Surface protective layer forming composition 8) Thermosetting resin (acrylic polyol): 93 parts by mass Crosslinking agent (isocyanate): 7 parts by mass Solvent: appropriate amount

[0128] The adhesive layer ink was applied to the surface of the resin substrate opposite to the surface protective layer by gravure printing. The applied ink was then dried at 120°C for 1 minute to form an adhesive layer having a thickness of 30 µm. This resulted in a protective film having the surface protective layer, resin substrate, and adhesive layer in this order.

[0129] Comparative Example 5 The above-mentioned acrylic film (ACRYPLEN HBS006H (manufactured by Mitsubishi Chemical Corporation, thickness 53 μm)) was prepared as a resin substrate.

[0130] A composition containing a fluororesin (PVDF) was applied to one surface of the resin substrate and dried to form a fluororesin layer having a thickness of 7 μm as a surface protection layer.

[0131] The adhesive layer ink was applied to the surface of the resin substrate opposite the surface protective layer by gravure printing. The applied ink was then dried at 120°C for 1 minute to form an adhesive layer having a thickness of 30 µm. This resulted in a protective film having a fluororesin layer, a resin substrate, and an adhesive layer in this order.

[0132] Comparative Example 6 The above-mentioned acrylic film (ACRYPLEN HBS006H (manufactured by Mitsubishi Chemical Corporation, thickness 53 μm)) was prepared as a resin substrate.

[0133] (Measurement of Nanoindentation Hardness) The nanoindentation hardness of the surface was measured by the method described above for the surface protective layers of the protective films obtained in Examples 1 to 4 and Comparative Examples 1 to 5. The results are shown in Table 1.

[0134] (Evaluation: Solvent Resistance) The protective films obtained in Examples 1 to 4 and Comparative Examples 1 to 6 were subjected to a load of 200 g / cm using gauze soaked in acetone. ２ The surface on the surface protective layer side was rubbed back and forth 20 times with a rubbing cloth. The 60° gloss value of the surface on the surface protective layer side of the protective film before and after the test was measured by the method described above, and the gloss change rate (%) was calculated using the following formula and evaluated according to the following evaluation criteria. Gloss change rate (%) = (gloss value after test / gloss value before test) x 100 (%) AA: No change in gloss (gloss change rate: 100% or more and less than 105%) A: Slight change in gloss (gloss change rate: 105% or more and less than 115%) B: Moderate change in gloss (gloss change rate: 115% or more and less than 120%) C: Large change in gloss (gloss change rate: 120% or more)

[0135] (Evaluation: Scratch Resistance) The protective films obtained in Examples 1 to 4 and Comparative Examples 1 to 6 were scratched with Bonstar steel wool #0000 under a load of 200 g / cm. ２The surface on the surface protective layer side was rubbed back and forth 20 times with a rubbing cloth. The 60° gloss value of the surface on the surface protective layer side of the protective film before and after the test was measured by the method described above, and the gloss change rate was calculated using the following formula and evaluated according to the following evaluation criteria. Gloss change rate (%) = (gloss value after test / gloss value before test) x 100 (%) AA: No change in gloss (gloss change rate: 100% or more and less than 105%) A: Slight change in gloss (gloss change rate: 105% or more and less than 115%) B: Moderate change in gloss (gloss change rate: 115% or more and less than 120%) C: Large change in gloss (gloss change rate: 120% or more)

[0136] (Evaluation: Bending Suitability) The protective films obtained in Examples 1 to 4 and Comparative Examples 1 to 6 were cut to A5 size (210 mm long x 148 mm wide). Next, the cut protective films were wrapped around a rectangular metal member measuring 50 mm long x 50 mm wide x 150 mm deep. As shown in FIG. 4 , during wrapping, the protective film was oriented so that the horizontal direction of the protective film was parallel to the depth direction of the metal member, and the protective film was attached so that the adhesive layer side of the protective film was in contact with the metal member. After wrapping, the protective film surface at the corners was observed to check for the occurrence of whitening and cracking, and the results were evaluated according to the following evaluation criteria: AA: No whitening or cracking was observed. A: Minor whitening or cracking was observed. B: Moderate whitening or cracking was observed. C: Large-scale whitening or cracking was observed.

[0137]

[0138] As shown in Table 1, it was confirmed that in Examples 1 to 4, laminates with good solvent resistance, scratch resistance, and bending suitability were obtained. On the other hand, in Comparative Example 1, the nanoindentation hardness of the surface protective layer was too high, resulting in poor bending suitability. In Comparative Example 2, the surface protective layer was too thick, resulting in poor bending suitability. In Comparative Examples 3 and 4, the surface protective layer was too thin, resulting in poor solvent resistance and scratch resistance. In Comparative Example 5, the surface protective layer contained a fluorine compound resin, resulting in poor solvent resistance and scratch resistance. In Comparative Example 6, which did not have a surface protective layer, the solvent resistance and scratch resistance were poor.

[0139] Thus, the present disclosure provides, for example, the following inventions.

[0140] [1] A protective film having a resin substrate and a surface protective layer disposed on one surface of the resin substrate, wherein the surface protective layer contains a cured product of at least one of an ionizing radiation curable resin and a thermosetting resin, the thickness of the surface protective layer is 3.0 μm or more and 15 μm or less, and the nanoindentation hardness of the surface protective layer is 100 MPa or more and 350 MPa or less.

[0141] [2] The protective film according to [1], wherein the resin substrate contains a (meth)acrylic resin.

[0142] [3] The protective film according to [2], wherein the (meth)acrylic resin is polymethyl(meth)acrylate.

[0143] [4] The protective film according to any one of [1] to [3], wherein the resin substrate contains a weathering agent.

[0144] [5] The protective film according to [4], wherein the resin substrate contains a triazine-based ultraviolet absorber as the weather resistance agent.

[0145] [6] The protective film according to any one of [1] to [5], which has a primer layer between the resin substrate and the surface protective layer.

[0146] [7] The protective film according to any one of [1] to [6], wherein the thickness of the resin substrate is 30 μm or more and 150 μm or less.

[0147] [8] The protective film according to any one of [1] to [7], which has a heat seal layer, an adhesive layer, or a back primer layer on the surface of the resin substrate opposite to the surface protective layer.

[0148] [9] The protective film according to any one of [1] to [8], wherein the 60° gloss value of the surface of the protective film on the surface protective layer side is 25 or less.

[0149]

[10] A laminate comprising an adherend and the protective film according to any one of [1] to [9].

[0150]

[11] The laminate according to

[10] , wherein the adherend is any one of a resin member, a glass member, and a wooden member.

[0151] REFERENCE SIGNS LIST 1... resin substrate 2... surface protective layer 3... adhesive layer 4... primer layer 10... protective film 50... adherend 100... laminate

Claims

1. A protective film having a resin substrate and a surface protective layer disposed on one side of the resin substrate, wherein the surface protective layer contains a cured product of at least one of an ionizing radiation curable resin and a thermosetting resin, the thickness of the surface protective layer is 3.0 μm or more and 15 μm or less, and the nanoindentation hardness of the surface of the surface protective layer is 100 MPa or more and 350 MPa or less.

2. The protective film according to claim 1, wherein the resin substrate contains a (meth)acrylic resin.

3. The protective film according to claim 2, wherein the (meth)acrylic resin is polymethyl(meth)acrylate.

4. The protective film according to claim 1, wherein the resin substrate contains a weathering agent.

5. The protective film according to claim 4, wherein the resin substrate contains a triazine-based ultraviolet absorber as the weather resistance agent.

6. The protective film according to claim 1, which has a primer layer between the resin substrate and the surface protective layer.

7. The protective film according to claim 1, wherein the thickness of the resin substrate is 30 μm or more and 150 μm or less.

8. The protective film according to claim 1, which has one of a heat seal layer, an adhesive layer and a back primer layer on the surface of the resin substrate opposite to the surface protective layer.

9. The protective film according to claim 1, wherein the 60° gloss value of the surface of the protective film on the surface protective layer side is 25 or less.

10. A laminate comprising an adherend and a protective film according to any one of claims 1 to 9.

11. The laminate according to claim 10, wherein the adherend is any one of a resin member, a glass member, and a wood member.

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