JP2014109712A - Hard coat film, decorative film and protective film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hard coat film having preferable surface hardness and little interference fringes.SOLUTION: The hard coat film includes a hard coat layer on at least one surface of a film substrate, in which the film substrate comprises an acrylic resin film substrate having a Martens hardness scale of 120 N/mmor more measured by pushing a Vickers indenter having an interridge angle of 136° to the substrate surface under a weight of 1 mN. The hard coat film achieves preferable surface hardness and reduction of interference fringes and can be preferably used as a protective film or the like for various types of displays such as a smartphone and a tablet PC mounting a touch panel.

Description

  The present invention relates to a hard coat film having a suitable surface hardness and less interference fringes, for example, a hard coat film suitably used as a protective film for various displays such as smartphones and tablet PCs.

  In an image display window of an image display device such as a liquid crystal display device used for a small electronic terminal such as a smartphone or a tablet PC, a protective film is provided to prevent the image display device from being damaged or damaged (for example, Patent Document 1). In recent years, an increase in the number of touch panels mounted on electronic terminals has led to a demand for a protective film having a high hardness that prevents damage from touching the screen directly with a finger or a touch pen. However, the conventional protective film has a problem that the surface hardness is low and it is difficult to prevent damage when the image display window of the image display device is rubbed with a touch pen or the like.

  Moreover, in the conventional protective film, there was a problem that interference fringes occurred due to a large difference in refractive index between the hard coat layer and the film layer of the protective film, and the visibility when viewing the image of the electronic terminal was deteriorated.

Japanese Patent Application No. 2009-9792

  The problem to be solved by the present invention is to provide a hard coat film having a suitable surface hardness and less interference fringes.

The present invention is a hard coat film having a hard coat layer on at least one surface of a film substrate, wherein the film substrate is measured by pressing a Vickers indenter having a ridge angle of 136 ° into the surface with a load of 1 mN. The above problem is solved by a hard coat film which is an acrylic resin film substrate having a thickness of 120 N / mm ² or more.

  Since the hard coat film of the present invention has a suitable surface hardness and less interference fringes, it is suitably used as a protective film for various displays such as smartphones and tablet PCs equipped with a touch panel.

The present invention is a hard coat film having a hard coat layer on at least one surface of a film substrate, wherein the film substrate is measured by pressing a Vickers indenter having a ridge angle of 136 ° into the surface with a load of 1 mN. A hard coat film using an acrylic resin film having a thickness of 120 N / mm ² or more as a substrate.

[Hard coat layer]
As the hard coat layer used in the present invention, a hard coat layer usually used as a protective film for an image display window can be used, and a hard coat layer that can prevent scratches can be used. The hard coat layer is preferably a hard coat agent having a surface hardness of 3H or more when applied to a 1 mm thick glass surface with a thickness of 10 μm, and more preferably 4H or more. By increasing the hardness, the ability to prevent damage to the image display window can be improved. The surface hardness is a surface hardness measured with a load of 1 kg in accordance with JIS K 5600-5-4.

  As the hard coat layer, one having high transparency or one containing no polarizing substance is preferable because it becomes easy to obtain suitable visibility. As the transparency of the hard coat layer, the total light transmittance of the hard coat layer is 85%, preferably 90% or more. The haze value is preferably 1.0 or less, and particularly preferably 0.5 or less.

  The refractive index of the hard coat layer is preferably 1.45 to 1.55, and more preferably 1.51 to 1.54. By setting the refractive index of the hard coat layer within this range, it becomes easy to adjust the refractive index difference from the commonly used acrylic resin film substrate to less than 0.1.

  The thickness of the hard coat layer is preferably 5 to 25 μm, and more preferably 10 to 15 μm. By setting it within this range, it is easy to obtain a suitable surface hardness, and it can be suitably applied to an image display device that is highly demanded of thinning.

  As the hard coat agent used for the hard coat layer, since the hard coat layer can be easily formed, a hard coat agent comprising an active energy ray-curable resin composition can be suitably used. As such an active energy ray-curable resin composition, a polyfunctional acrylate resin composition is preferable, and among them, a hard coat agent containing urethane (meth) acrylate can be preferably used. As urethane (meth) acrylate, various urethane (meth) acrylates used for hard coating agents can be used, among them, acrylate (a1) having a hydroxyl group and two or more (meth) acryloyl groups, and a polyisocyanate. What contains polyfunctional urethane (meth) acrylate (A) obtained by making it react with (a2) as an essential component is preferable.

  Examples of the acrylate (a1) having one hydroxyl group and two or more (meth) acryloyl groups in one molecule used in the present invention include trimethylolpropane di (meth) acrylate, pentaerythritol tri (meth) acrylate, penta Examples include polyacrylates of polyhydric hydroxyl group-containing compounds such as erythritol tetra (meth) acrylate and dipentaerythritol penta (meth) acrylate, adducts of these polyacrylates with ε-caprolactone, and these polyacrylates Examples include adducts with alkylene oxides and epoxy acrylates. These acrylates (a1) can be used alone or in combination of two or more.

  Of these acrylates (a1), an acrylate having one hydroxyl group and 3 to 5 (meth) acryloyl groups in one molecule is preferable. Examples of such acrylates include pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, and the like, and these are particularly preferable because a cured film having high hardness can be obtained.

  Examples of the polyisocyanate (a2) used in the present invention include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,3-xylylene diisocyanate, 4,4′-diphenyl diisocyanate, 1,5- Aromatic isocyanate compounds such as naphthalene diisocyanate and 4,4'-diphenylmethane diisocyanate; Alicyclic rings such as dicyclohexylmethane diisocyanate, isophorone diisocyanate, norbornane diisocyanate, hydrogenated xylylene diisocyanate, hydrogenated methylenebisphenylene diisocyanate, and 1,4-cyclohexane diisocyanate A compound having two isocyanate groups bonded to a hydrocarbon (hereinafter abbreviated as alicyclic diisocyanate); trimethylene diisocyanate, hexamethyl Compounds having two isocyanate groups attached to aliphatic hydrocarbons such as emissions diisocyanate (hereinafter, abbreviated as aliphatic diisocyanates.) And the like. These polyisocyanates can be used alone or in combination of two or more.

  Further, these polyisocyanates (a2) give high toughness to the coating film, and cracks and the like are less likely to occur. Therefore, aliphatic diisocyanates or alicyclic diisocyanates are preferred, and among them, isophorone diisocyanate, norbornane diisocyanate, hydrogenated xylylene. Range isocyanate, hydrogenated methylene bisphenylene diisocyanate and hexamethylene diisocyanate, 1,6-hexamethylene diisocyanate, dicyclohexylmethane-4,4′-diisocyanate are preferred.

  In particular, when forming a hard coat layer to be used as the outermost layer of the image display unit, as described above, in order to realize a balance between high hardness and shrinkage rate, as the hard coat agent used for the hard coat layer, active energy rays are used. The cured coating film preferably contains two or more different cyclic skeletons, and at least one of them is an active energy ray-curable resin composition that is a heterocyclic compound. As the active energy ray-curable resin used for the hard coating agent, a monofunctional one may be used, but in order to obtain high pencil hardness, a polyfunctional (meth) acrylate is preferable. For example, polyisocyanate ( Among a2), it is an addition reaction product of polyisocyanate (a2-1) having a cyclic skeleton and acrylate (a1-1) having one hydroxyl group and two or more (meth) acryloyl groups in one molecule. Examples thereof include cyclic skeleton-containing urethane acrylate. Particularly preferred is a urethane acrylate containing a cyclic skeleton obtained by addition reaction of a polyfunctional acrylate and a polyisocyanate having a cyclic skeleton, although it contains two or more cyclic skeletons, one of which is a heterocyclic skeleton. Thus, it is possible to obtain a coating film having a good balance between pencil hardness and curl after active energy ray curing.

  As a method for introducing a heterocyclic skeleton, for example, a polyfunctional (meth) acrylate having a cyclic skeleton and a polyfunctional (meth) acrylate containing a heterocyclic skeleton may be blended, respectively. Polyfunctional (meth) acryloyl containing a heterocyclic skeleton different from (a2-1) in acrylate (a1) having one hydroxyl group and two or more (meth) acryloyl groups in isocyanate (a2-1) and one molecule An active energy ray-curable resin composition containing two or more different types of cyclic skeletons in one molecule using an acrylate (a1-2) having a group, and at least one of which is a heterocyclic skeleton, is obtained. It doesn't matter. Other methods for introducing two or more kinds of cyclic skeletons into one molecule include, for example, those obtained by adding the above (a1-2) to a trimer of polyisocyanate (a2-2) having an alicyclic cyclic skeleton Etc.

  Examples of the heterocyclic skeleton-containing polyfunctional acrylate (a1-2) include bis (acryloxyethyl) hydroxyethyl isocyanurate (Aronix M-215). As the single heterocyclic skeleton-containing polyfunctional (meth) acrylate, for example, bis (acryloxyethyl) hydroxyethyl isocyanurate (Aronix M-215), tris (2-hydroxyethyl) isocyanate triacrylate (Aronix M-315) , Caprolactone-modified tris (acryloxyethyl) isocyanurate (Aronix M-325), neopentyl glycol-modified trimethylolpropane diacrylate (Kayarad R-604), and the like.

  The urethane acrylate (A) used in the present invention is obtained by subjecting two components of the polyisocyanate (a2) and the acrylate (a1) to an addition reaction. The ratio of the acrylate (a1) to 1 equivalent of isocyanate in the polyisocyanate (a2) is usually preferably 0.1 to 50, more preferably 0.1 to 10, and preferably 0.9 to 1.3 as a hydroxyl equivalent. Is more preferable, and 1.01-1.24 is particularly preferable. Moreover, 30-150 degreeC is preferable and, as for the reaction temperature of the said polyisocyanate (a2) and the said acrylate (a1), 50-100 degreeC is more preferable. In addition, the end point of reaction can be confirmed by calculating | requiring an isocyanate group content rate by the loss | disappearance of the infrared absorption spectrum of 2250cm <-1> which shows an isocyanate group, or the method as described in JISK7301-1995, for example. Moreover, it is preferable that the average of the (meth) acryloyl group of urethane (meth) acrylate (A) is five or more.

  The molecular weight of the urethane acrylate (A) is preferably in the range of 500 to 1,500. When the molecular weight is within this range, a cured film having a sufficiently high hardness can be obtained and curing shrinkage can be reduced. Therefore, the curl of the film having the cured film can be easily reduced, which is preferable.

  The blending amount of the urethane acrylate (A) in 100 parts by weight of the resin component in the resin composition is preferably 5 to 90 parts by weight, more preferably 10 to 70 parts by weight, and even more preferably 10 to 60 parts by weight. . If the blending amount of the urethane acrylate (A) is within this range, a cured film having a sufficiently high hardness can be obtained, and there is no coating film defect, excellent surface antifouling properties, and curing shrinkage is reduced. This is preferable because the curl of the film having a cured coating can be easily reduced.

  In addition to the urethane acrylate (A), a urethane acrylate (B) other than the urethane acrylate (A) may be added to the active energy ray-curable resin composition used in the present invention. The urethane acrylate (B) is an acrylate (a1) having one hydroxyl group and two or more (meth) acryloyl groups in one molecule after an addition reaction between a polyol and the polyisocyanate (a2). Can be added. 10-150 weight part is preferable with respect to 100 weight part of said urethane acrylate (A), and, as for the compounding quantity at the time of mix | blending this urethane acrylate (B) in a resin composition, 50-130 weight part is more preferable.

  Moreover, in order to obtain high pencil hardness, the active energy ray-curable resin composition used for the hard coating agent may be blended with a polymer having a high (meth) acryloyl group equivalent, or with an inorganic compound such as silica. preferable. As the polymer (C), for example, with respect to the (meth) acrylate polymer (c1) having a hydroxyl group, a carboxyl group, an epoxy group, etc. as a reactive functional group in the side chain, Examples thereof include a polymer having a (meth) acryloyl group obtained by reacting an α, β-unsaturated compound (c2) having a functional group such as an isocyanate group, a carboxyl group, an acid halide group, a hydroxyl group and an epoxy group capable of reacting. .

  As the photoinitiator used for the active energy ray-curable resin composition used as the hard coat agent, various materials can be used. Among them, benzophenone, benzyl, Examples include compounds that generate radicals by hydrogen abstraction such as Michler's ketone, thioxanthone, and anthraquinone. These compounds are generally used in combination with a tertiary amine such as methylamine, diethanolamine, N-methyldiethanolamine, or tributylamine that serves as a hydrogen abstracting agent.

  Another type of photopolymerization initiator includes, for example, a type of compound that generates radicals by intramolecular splitting. Specific examples include benzoin, dialkoxyacetophenone, acyloxime ester, benzyl ketal, hydroxyalkylphenone, halogenoketone and the like.

  Moreover, in the active energy ray-curable resin composition used as a hard coat agent for forming the hard coat layer, the amount of the active initiator used when the photoinitiator is added to the active energy ray-curable resin composition is the active energy. It is preferable to mix | blend 1-10 weight part with respect to 100 weight part of total weights of a linear curable resin composition, and it is still more preferable to mix | blend 4-9 weight part.

  Further, if necessary, a polymerization inhibitor such as hydroquinone, benzoquinone, tolhydronoquinone, paratertiary butylcatechol, etc. can be added in combination with a photopolymerization initiator.

  In the hard coat agent for forming the hard coat layer corresponding to the outermost layer of the image display unit used in the present invention, for the purpose of improving the surface properties such as surface slipperiness, stain resistance, and fingerprint resistance of the protective layer, the above An additive comprising a composition containing a compound having a fluorocarbon chain, a dimethylsiloxane chain, and a hydrocarbon chain having 12 or more carbon atoms may be added to the active energy ray-curable resin composition used for the hard coating agent. preferable. The additive amount of the additive containing a compound having a fluorocarbon chain, a dimethylsiloxane chain and a hydrocarbon chain having 12 or more carbon atoms is preferably 0.05 to 5% by weight with respect to the active energy ray-curable resin composition. 0.1 to 2% by weight is more preferable.

  Among these, a compound containing a fluorocarbon chain can be suitably used because it is excellent in surface properties such as stain resistance, fingerprint resistance, and magic wiping property. In particular, a heterocyclic ring is bonded to one or both ends of a poly (perfluoroalkylene ether) chain via a divalent linking group, and the heterocyclic ring has two or more (meta-metabolites via a divalent linking group. ) A compound having an acryloyl group bonded thereto is preferable.

[Film substrate]
The film substrate used in the present invention has a Martens hardness of 120 N / mm ² or more measured by pushing a Vickers indenter with a ridge angle of 136 ° into the surface with a load of 1 mN.

Furthermore, Martens hardness of the acrylic resin film base is preferably ^{125~300N / mm 2, 130~200N / mm} 2 being most preferred. A suitable surface hardness can be realized by using an acrylic resin film having a Martens hardness within the above range as a substrate. Further, when the obtained hard coat film and the pressure-sensitive adhesive layer are laminated, the surface hardness is hardly lowered, and good processability is easily obtained.

  The indentation elastic modulus measured by indenting a Vickers indenter with a ridge angle of 136 ° into the surface of the acrylic resin film substrate with a load of 1 mN is preferably 2000 MPa or more, and more preferably 2000 to 3000 MPa. By using an acrylic resin film in this range as a base material, it becomes easy to achieve both a suitable surface hardness and good workability.

  The Martens hardness and indentation elastic modulus of the acrylic resin film are the Martens hardness and indentation elastic modulus measured in an environment of 23 ° C., for example, measured using FISCHERSCOPE / HM2000LT (manufactured by Fisher Instruments). The

  The acrylic resin film substrate preferably has high transparency from the viewpoint of use in an image display device. The total light transmittance in the visible light wavelength region of the acrylic resin film substrate of the present invention is preferably 85% or more, more preferably 90% or more, and the haze is preferably 1.0 or less, particularly preferably 0.5 or less. By setting the total light transmittance and the haze within the above ranges, it is easy to impart high transparency to the protective film, and the display screen can be easily refined when applied to an image display device.

  The acrylic resin film substrate preferably has a refractive index difference of less than 0.1 with respect to the hard coat layer, and more preferably 0.06 or less. By reducing the refractive index difference between the hard coat layer and the acrylic film substrate, interference fringes can be reduced.

  The refractive index of the acrylic resin film substrate is preferably 1.45 to 1.55, and more preferably 1.47 to 1.53. By making the refractive index of an acrylic resin film into this range, it becomes easy to adjust the refractive index difference with the acrylic resin film base material generally used to less than 0.1.

  The thickness of the pre-acrylic resin film substrate is preferably 150 μm or less, more preferably 75 to 140 μm, and more preferably 100 to 125 μm. By making the thickness of the acrylic resin film substrate within this range, it is possible to favorably contribute to thinning of the image display device while having a suitable surface hardness.

[Hard coat film]
The hard coat film of the present invention may have a structure having a hard coat layer on one surface of the substrate or a structure having hard coat layers on both surfaces of the substrate. The former configuration is preferable because it is easy to realize good workability as well as thinning, and the latter configuration is preferable because high surface hardness and scratch resistance are easily realized.

  As the surface hardness of the hard coat film, the pencil hardness is preferably 2H or more, more preferably 3H or more, and particularly preferably 4H or more because of scratch resistance. When the hard coat film is a double-sided hard coat film having hard coat layers on both sides, the pencil hardness of the back side hard coat layer is preferably H or higher, more preferably 2H or higher.

  The total light transmittance of the hard coat film of the present invention is preferably 85% or more, more preferably 88% or more, and further preferably 90% or more. In this invention, it can use suitably as a protective film of an image display apparatus by making a total light transmittance into the said range.

  The thickness of the hard coat film is preferably 200 μm or less, and preferably 150 μm or less, in order to reduce the thickness of the image display device.

  The hard coat film used in the present invention can be produced by applying and curing a hard coat agent used for the hard coat layer on at least one surface of the substrate.

  Examples of methods for applying a hard coating agent to a film substrate include gravure coating, roll coating, comma coating, air knife coating, kiss coating, spray coating, transfer coating, dip coating, spinner coating, wheeler coating, brush coating, and silk. Examples thereof include a solid coat using a screen, a wire bar coat, and a flow coat. Also, printing methods such as offset printing and letterpress printing may be used. Among these, gravure coating, roll coating, comma coating, air knife coating, kiss coating, wire bar coating, and flow coating are preferable because a coating film having a more constant thickness can be obtained.

  The hard coat agent curing device may be appropriately used according to the hard coat agent to be used, but when using the active energy ray-curable resin composition used for the hard coat agent as a hard coat agent, What is necessary is just to harden | cure by active energy rays, such as an electron beam and a radiation. Specific energy sources or curing devices include, for example, germicidal lamps, ultraviolet fluorescent lamps, carbon arc, xenon lamps, high pressure mercury lamps for copying, medium or high pressure mercury lamps, ultrahigh pressure mercury lamps, electrodeless lamps, metal halide lamps, natural light, etc. Or an electron beam using a scanning type or curtain type electron beam accelerator.

  Among these, ultraviolet rays are particularly preferable, and irradiation in an inert gas atmosphere such as nitrogen gas is preferable in terms of increasing the polymerization efficiency. Further, if necessary, heat may be used as an energy source and heat treatment may be performed after curing with active energy rays.

  When ultraviolet rays are used as a device for irradiating active energy rays, the light source is a low pressure mercury lamp, high pressure mercury lamp, ultra high pressure mercury lamp, metal halide lamp, electrodeless lamp (fusion lamp), chemical lamp, black light. Lamps, mercury-xenon lamps, short arc lamps, helium / cadmium lasers, argon lasers, sunlight, LEDs and the like can be mentioned. In addition, when the active energy ray-curable resin composition used in the present invention is applied to a film substrate to form a cured film, a flashing xenon-flash lamp is used. This is preferable because the influence of heat can be reduced.

  In the case of continuous production by roll-to-roll, the hard coat film is wound up in a roll shape, so that the hard coat layer to be applied / cured and the other surface having the hard coat layer are in contact with each other. As described above, when an additive such as a fluorocarbon chain or a dimethylsiloxane chain is used in the hard coat layer, the additive component may migrate to the surface on which the hard coat film is to be decorated, and may contaminate the surface. . In the hard coat film used in the present invention, in order to avoid the contamination on the surface to be decorated, the surface on which the hard coat layer is applied or the hard coat at the same time in the step of applying and curing the hard coat agent on the film substrate A protective film may be laminated on the other surface to which the layer is applied.

[Decorative film]
The hard coat film of the present invention may be a decorative film by providing a decorative layer on at least one surface thereof. The decorative layer imparts various design properties to the hard coat film. As the decoration layer, for example, characters and figures visually recognized around the image display unit when used as an image display panel, or a black border-like decoration layer provided in a frame shape on the image display unit, etc. Is mentioned. Especially, when using the decoration layer provided in frame shape in an image display part, it is easy to express the effect of this invention especially suitably.

  As a method of providing the decorative layer on the hard coat film, a method by printing is simple, which is preferable. Examples of the printing method include a silk printing method, a screen printing method, a gravure printing method, and a thermal transfer printing method. Among these, a silk printing method, a screen printing method, and a thermal transfer printing method capable of printing a decorative layer having a high concealment property are preferable.

  As the ink used in the silk printing method and the screen printing method, various inks used for printing on a film can be used, and a solvent system or a UV curing system is used. In particular, solvent-based inks are preferably used because they only need to dry the solvent in a drying furnace, and therefore can be printed at low cost because no device such as a UV irradiation device is required.

  As the ink used for the thermal transfer system, a resin type or a wax type is used. Of these, the resin type is preferably used because of its excellent weather resistance.

  As thickness of a decoration layer, 30 micrometers or less are preferable, 1-15 micrometers is more preferable, and 2-10 micrometers is especially preferable. By setting it as the decorating layer of the said thickness, it is hard to produce a suitable color omission and a printing defect, and it becomes easy to obtain suitable designability.

[Protective film]
The hard coat film of the present invention may be provided with a pressure-sensitive adhesive layer on one side to form a protective film. The pressure-sensitive adhesive layer can be provided by sticking a pressure-sensitive adhesive tape to the acrylic resin film substrate or by directly applying a pressure-sensitive adhesive layer to the surface opposite to the hard coat surface of the acrylic resin film substrate. The protective film may have a configuration in which an adhesive layer is provided on one surface of a hard coat film provided with a decorative layer.

  The thickness of the pressure-sensitive adhesive layer of the protective film of the present invention is preferably in the range of 5 to 50 μm, more preferably in the range of 8 to 30 μm, and still more preferably in the range of 10 to 25 μm. In this invention, by making the thickness of an adhesive layer into the said range, it is excellent in adhesive reliability, and can maintain the surface hardness of a hard coat film not remarkably impaired.

  As the pressure-sensitive adhesive used in the pressure-sensitive adhesive layer used in the present invention, known acrylic, rubber-based, silicone-based pressure-sensitive resins can be used. Among them, an acrylic copolymer obtained by polymerizing a (meth) acrylate monomer having an alkyl group having 2 to 14 carbon atoms as a repeating unit as a main component reduces interference fringes and adhesion to a film substrate. From the viewpoint of transparency and weather resistance. Among them, an acrylic copolymer having a refractive index of 1.48 to 1.54 is more preferable from the viewpoint of reducing interference fringes.

  Examples of the (meth) acrylate monomer having 2 to 14 carbon atoms include ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, sec-butyl acrylate, t-butyl acrylate, and n-hexyl acrylate. , Cyclohexyl acrylate, n-octyl acrylate, isooctyl acrylate, 2-ethylhexyl acrylate, isononyl acrylate, isodecyl acrylate, lauryl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, sec- Butyl methacrylate, t-butyl methacrylate, n-hexyl methacrylate, cyclohexyl methacrylate, n Octyl methacrylate, isooctyl methacrylate, 2-ethylhexyl methacrylate, isononyl methacrylate, isodecyl methacrylate, lauryl methacrylate and the like.

  Among the (meth) acrylate monomers, an alkyl (meth) acrylate having an alkyl group having 4 to 9 carbon atoms is preferable, and an alkyl acrylate having an alkyl group having 4 to 9 carbon atoms is more preferable. preferable. Of the alkyl acrylates, n-butyl acrylate, isooctyl acrylate, 2-ethylhexyl acrylate, isononyl acrylate, and ethyl acrylate are particularly preferable. By using an alkyl (meth) acrylate having an alkyl group having the number of carbon atoms in the range, it is easy to ensure a suitable adhesive force.

  The content of the (meth) acrylate having 2 to 14 carbon atoms in the monomer constituting the acrylic copolymer used in the pressure-sensitive adhesive layer of the present invention is preferably 90 to 99% by mass, 90 More preferably, it is made -96 mass%. By setting the content of the (meth) acrylate in this range, it is easy to ensure a suitable adhesive force.

  For acrylic copolymers, (meth) acrylate monomers having polar groups such as hydroxyl, carboxyl and amide groups and vinyl monomers having other polar groups should be used as monomer components. Is preferred.

  Examples of the (meth) acrylate monomer having a hydroxyl group include 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, hydroxypropyl (meth) acrylate, Examples include caprolactone-modified (meth) acrylate, polyethylene glycol mono (meth) acrylate, and polypropylene glycol mono (meth) acrylate. Among these, 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and 6-hydroxyhexyl (meth) acrylate are preferably used.

  Examples of the (meth) acrylate monomer having a carboxyl group include acrylic acid, methacrylic acid, itaconic acid, maleic acid, crotonic acid, acrylic acid or methacrylic acid dimer, ethylene oxide-modified succinic acid acrylate, and the like. Can be mentioned. Among these, it is preferable to use acrylic acid.

  Examples of the (meth) acrylate monomer having an amide group include N-vinyl-2-pyrrolidone, N-vinylcaprolactam, acryloylmorpholine, acrylamide, N, N-dimethylacrylamide, and 2- (perhydrophthalimide-N. -Yl) ethyl acrylate and the like. Among these, it is preferable to use N-vinyl-2-pyrrolidone, N-vinylcaprolactam, and acryloylmorpholine.

  Examples of the other vinyl monomers having a polar group include vinyl acetate, acrylonitrile, maleic anhydride, itaconic anhydride and the like.

  The content of the monomer having a polar group is preferably 0.1 to 20% by mass, more preferably 1 to 13% by mass of the monomer component constituting the acrylic copolymer. More preferably, it is 1.5 to 8% by weight. By containing a monomer having a polar group within this range, it is easy to adjust the cohesive strength, holding power, and adhesiveness of the pressure-sensitive adhesive within a suitable range.

  The weight average molecular weight Mw of the acrylic copolymer used for the pressure-sensitive adhesive layer is preferably 400,000 to 1,400,000, and more preferably 600,000 to 1,200,000. When the weight average molecular weight Mw of the acrylic copolymer is within the range, it is easy to adjust the adhesive force to a specific range.

The weight average molecular weight Mw can be measured by gel permeation chromatography (GPC). More specifically, as a GPC measurement device, “SC8020” manufactured by Tosoh Corporation can be used to measure and obtain the following GPC measurement conditions based on polystyrene conversion values.
(GPC measurement conditions)
Sample concentration: 0.5% by weight (tetrahydrofuran solution)
Sample injection volume: 100 μL
・ Eluent: Tetrahydrofuran (THF)
・ Flow rate: 1.0 mL / min
Column temperature (measurement temperature): 40 ° C
Column: “TSKgel GMHHR-H” manufactured by Tosoh Corporation
・ Detector: Differential refraction

  Further, in order to increase the cohesive strength of the pressure-sensitive adhesive layer, it is preferable to add a crosslinking agent in the pressure-sensitive adhesive. As a crosslinking agent, an isocyanate type crosslinking agent, an epoxy type crosslinking agent, a chelate type crosslinking agent etc. are mentioned, for example. The addition amount of the crosslinking agent is preferably adjusted so that the gel fraction of the pressure-sensitive adhesive layer is 25 to 80% by mass, more preferably adjusted to be 40 to 75% by mass, and 50 to 70% by mass. It is most preferable to adjust so that. By adjusting the gel fraction within the range, the surface pencil hardness can be suppressed when the protective film is attached to the substrate, and the adhesiveness can be sufficient. The gel fraction in the present invention is expressed as a percentage of the original mass by immersing the cured pressure-sensitive adhesive layer in toluene, measuring the mass after drying of the insoluble matter remaining after standing for 24 hours, and the original mass. Is.

  Furthermore, in order to improve the adhesive strength of the pressure-sensitive adhesive layer, a tackifier resin may be added. As addition amount of tackifying resin, when an adhesive resin is an acrylic copolymer, it is preferable to add in 10-60 mass parts with respect to 100 mass parts of acrylic copolymers. Furthermore, when importance is attached to adhesiveness, it is preferable to add in the range of 20-50 mass parts.

  Moreover, a well-known and usual additive other than the above can be added to an adhesive. For example, in order to improve the adhesion to the glass substrate, it is preferable to add a silane coupling agent in the range of 0.001 to 0.005 parts by mass with respect to 100 parts by mass of the pressure-sensitive adhesive. Furthermore, a plasticizer, a softening agent, a filler, a pigment, a flame retardant, etc. can also be added as other additives as needed.

  Since the protective film of the present invention has suitable scratch resistance, it can be applied to various applications, and above all, it can be suitably applied to an image display unit of an image display device such as a liquid crystal display (LCD) or an organic EL display. In particular, because it can achieve suitable scratch resistance even if it is thin, images of portable electronic terminals that are highly demanded for miniaturization and thinning such as electronic notebooks, mobile phones, smartphones, portable audio players, mobile PCs, tablet terminals, etc. It is suitable as a protective film for an image display unit of a display device. In such an image display device, for example, an image display image display module such as an LCD module or an organic EL module is included in the configuration, and the image display image display module is protected above the image display image display module. In an image display device having a configuration in which a panel is provided, it is effective for preventing damage and scattering when the transparent panel is damaged by being attached to the front or back surface of the transparent panel.

  Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited to these.

(Synthesis Example 1)
<Synthesis of urethane acrylate (A1)>
In a flask equipped with a stirrer, a gas introduction tube, a cooling tube, and a thermometer, 250 parts by mass of butyl acetate, 206 parts by mass of norbornane diisocyanate (hereinafter referred to as “NBDI”), 0.5 parts by mass of p-methoxyphenol, dibutyl After charging 0.5 parts by mass of tin diacetate and raising the temperature to 70 ° C. while blowing air, pentaerythritol triacrylate (hereinafter referred to as “PE3A”) / pentaerythritol tetraacrylate (hereinafter referred to as “PE4A”). ) 795 parts by mass of a mixture (mixture having a mass ratio of 75/25) was added dropwise over 1 hour. After completion of the dropwise addition, the mixture is reacted at 70 ° C. for 3 hours, and further reacted until the infrared absorption spectrum of 2250 cm ⁻¹ showing the isocyanate group disappears, and the alicyclic compound-containing polyfunctional urethane acrylate (A1) / PE4A mixture (mass ratio) A 80/20 mixture, a butyl acetate solution having a nonvolatile content of 80% by mass) was obtained. The molecular weight (calculated value) of urethane acrylate (A1) is 802.

(Synthesis Example 2)
<Synthesis of urethane acrylate (A2)>
In a flask equipped with a stirrer, a gas introduction tube, a cooling tube, and a thermometer, 254 parts by mass of butyl acetate, 222 parts by mass of isophorone diisocyanate (hereinafter referred to as “IPDI”), 0.5 parts by mass of p-methoxyphenol, dibutyl After charging 0.5 parts by mass of tin diacetate and raising the temperature to 70 ° C., 795 parts by mass of a PE3A / PE4A mixture (a mixture with a mass ratio of 75/25) was added dropwise over 1 hour. After completion of the dropwise addition, the mixture is reacted at 70 ° C. for 3 hours, and further reacted until the infrared absorption spectrum of 2250 cm ⁻¹ showing the isocyanate group disappears, and the alicyclic compound-containing polyfunctional urethane acrylate (A2) / PE4A mixture (mass ratio) A 80/20 mixture, a butyl acetate solution having a nonvolatile content of 80% by mass) was obtained. The molecular weight (calculated value) of urethane acrylate (A2) is 818.

(Synthesis Example 3)
<Synthesis of urethane acrylate (A3)>
In a flask equipped with a stirrer, a gas introduction tube, a cooling tube, and a thermometer, 254 parts by mass of butyl acetate, 222 parts by mass of isophorone diisocyanate (hereinafter referred to as “IPDI”), 0.5 parts by mass of p-methoxyphenol, dibutyl After charging 0.5 parts by mass of tin diacetate and raising the temperature to 70 ° C., 369 parts by mass of 369 parts by mass of bis (acryloxyethyl) hydroxyethyl isocyanurate and a mixture of PE3A / PE4A (a mixture with a mass ratio of 75/25) The solution was added dropwise over 1 hour. After completion of the dropping, the reaction is carried out at 70 ° C. for 3 hours, and further, the reaction is continued until the infrared absorption spectrum of 2250 cm ⁻¹ showing the isocyanate group disappears, and a polyfunctional compound containing an alicyclic compound and a heterocyclic compound in one molecule. A urethane acrylate (A3) / PE4A mixture (a mixture having a mass ratio of 91/9, a butyl acetate solution having a nonvolatile content of 80% by mass) was obtained. The molecular weight (calculated value) of urethane acrylate (A3) is 889.

(Synthesis Example 4)
<Synthesis of urethane acrylate (A4)>
In a flask equipped with a stirrer, a gas introduction tube, a condenser and a thermometer, Aronics M-305 [Pentaerythritol triacrylate / pentaerythritol tetraacrylate = 60/40 (weight ratio) mixture manufactured by Toa Gosei Co., Ltd.], hydroxyl value 116 mg KOH / g] 549.1 parts, dibutyltin diacetate 0.1 part, Sumilizer BHT [Antioxidant manufactured by Sumitomo Chemical Co., Ltd.] 0.6 part, Metoquinone [polymerization inhibitor manufactured by Seiko Chemical Industry Co., Ltd.] 0.1 part and 160.0 parts of butyl acetate were added, and it heated up gradually, mixing uniformly. When the temperature reached 60 ° C., 90.9 parts of Desmodur H (Hexamethylene diisocyanate manufactured by Sumitomo Bayer Urethane Co., Ltd., NCO% = 50%) was added, followed by reaction at 80 ° C. for 5 hours to obtain urethane acrylate (A4) 800 Got a part.

(Synthesis Example 5)
<Synthesis of polymer (B1)>
In a flask equipped with a stirrer, a gas introduction tube, a cooling tube, and a thermometer, 250 parts by mass of glycidyl methacrylate (hereinafter referred to as “GMA”), 1.3 parts by mass of lauryl mercaptan, and methyl isobutyl ketone (hereinafter, “MIBK”). 1000 parts by mass and 7.5 parts by mass of 2,2′-azobisisobutyronitrile (hereinafter referred to as “AIBN”) were added and stirred at 90 ° C. over 1 hour while stirring under a nitrogen stream. The temperature was raised and reacted at 90 ° C. for 1 hour. Next, while stirring at 90 ° C., a mixed solution consisting of 750 parts by mass of GMA, 3.7 parts by mass of lauryl mercaptan, and 22.5 parts by mass of AIBN was dropped over 2 hours, and then reacted at 100 ° C. for 3 hours. Thereafter, 10 parts by weight of AIBN was charged, and further reacted at 100 ° C. for 1 hour, then heated to around 120 ° C. and reacted for 2 hours. Cool to 60 ° C., replace the nitrogen introduction tube with an air introduction tube, add 507 parts by mass of acrylic acid (hereinafter referred to as “AA”), 2 parts by mass of p-methoxyphenol, and 5.4 parts by mass of triphenylphosphine. After mixing, the reaction solution was bubbled with air, heated to 110 ° C., and reacted for 8 hours. Thereafter, 1.4 parts by mass of p-methoxyphenol was added, and after cooling to room temperature, MIBK was added so that the nonvolatile content was 50% by mass, and the polymer (B1) (MIBK solution having a nonvolatile content of 50% by mass) was added. Obtained. In addition, the weight average molecular weight of the obtained polymer (B1) was 31,000 (in terms of polystyrene by GPC), and the (meth) acryloyl group equivalent was 300 g / eq.

  Using the various urethane acrylates (A1) to (A4) and / or the polymer (B1) synthesized above, a hard coat agent composed of an active energy ray-curable resin composition was prepared as follows.

(Preparation Example 1)
Ethyl acetate 23.01 parts by mass, alicyclic compound-containing polyfunctional urethane acrylate (A1) / PE4A mixture (a mixture with a mass ratio of 80/20, butyl acetate solution with a nonvolatile content of 80% by mass) 19.64 parts by mass, alicyclic Formula compound-containing polyfunctional urethane acrylate (A2) / PE4A mixture (mixture with a mass ratio of 80/20, butyl acetate solution with a nonvolatile content of 80% by mass) 19.64 parts by mass, alicyclic compound and heterocyclic in one molecule Polyfunctional urethane acrylate (A3) / PE4A mixture containing a compound (mixture with a mass ratio of 91/9, butyl acetate solution with a nonvolatile content of 80% by mass) 15.71 parts by mass, dipentaerythritol hexaacrylate (hereinafter “DPHA”) 18.86 parts by mass, photoinitiator 1-hydroxycyclohexyl phenyl ketone (hereinafter referred to as “HCPK”) 2.51 parts by weight, photoinitiator diphenyl 2,4,6-trimethylbenzoylphosphine = oxide (hereinafter referred to as “TPO”) 0.63 parts by weight, reactive fluorine antifouling agent (OPTOOL DAC-HP; After uniformly mixing 2.0 parts by mass of Daikin Industries, Ltd. (nonvolatile content 20% by mass), the mixture is diluted with propylene glycol monomethyl ether (hereinafter referred to as “PGME”) so that the nonvolatile content becomes 40% by mass. Thus, a hard coating agent (1) was prepared. The hard coat agent (1) had a surface hardness of 4H when applied to glass with a film thickness of 10 μm.

(Preparation Example 2)
13.74 parts by mass of ethyl acetate, 47.08 parts by mass of alicyclic compound-containing polyfunctional urethane acrylate (A2) / PE4A mixture (mixture with a mass ratio of 80/20, butyl acetate solution with a nonvolatile content of 80% by mass), polymer (B1) (MIBK solution having a nonvolatile content of 50% by mass) 20.92 parts by mass, DPHA 12.74 parts by mass, photoinitiator HCPK 1.30 parts by mass, photoinitiator TPO 0.92 parts by mass, reactive fluorine antifouling agent ( Optool DAC-HP; Daikin Industries, Ltd., 20 parts by mass of non-volatile content 2.0 parts by mass uniformly mixed, and then propylene glycol monomethyl ether (hereinafter referred to as “PGME”) so that the non-volatile content is 40% by mass )) To prepare a hard coat agent (2). The hard coat agent (2) had a surface hardness of 4H when applied to glass with a film thickness of 10 μm.

(Adjustment Example 3)
After adding butyl acetate to urethane acrylate (A4) and diluting to a non-volatile content concentration of 35%, Irgacure # 184 [Photopolymerization initiator, 1-hydroxy-cyclohexyl, manufactured by Ciba Specialty Chemicals Co., Ltd.] -Phenyl-ketone] 3.2 parts was blended to prepare a hard coat agent (3). The hard coat agent (3) had a surface hardness of 3H when applied to glass with a film thickness of 10 μm.

Example 1
Using a 125 μm thick acrylic film (RT050 manufactured by Kuraray Co., Ltd., Martens hardness 138 [N / mm ² ]) as the base material, the hard coat agent (1) prepared above was applied to one side of the base material. After drying at 60 ° C. for 90 seconds, using an ultraviolet irradiation device (“F450” manufactured by Fusion UV Systems Japan Co., Ltd., lamp: 120 W / cm, H bulb) in an air atmosphere, the irradiation light quantity is 0.5 J / cm ^2. Was cured by irradiating with ultraviolet rays to form a hard coat layer having a thickness of 15 μm to obtain a hard coat film having a total thickness of 140 μm.

(Example 2)
Using a 125 μm thick acrylic film (SO manufactured by Kuraray Co., Ltd., Martens hardness 155 [N / mm ² ]) as the base material, the hard coat agent (1) prepared above was applied to one side of the base material. After drying at 60 ° C. for 90 seconds, using an ultraviolet irradiation device (“F450” manufactured by Fusion UV Systems Japan Co., Ltd., lamp: 120 W / cm, H bulb) in an air atmosphere, the irradiation light quantity is 0.5 J / cm ^2. Was cured by irradiating with ultraviolet rays to form a hard coat layer having a thickness of 15 μm to obtain a hard coat film having a total thickness of 140 μm.

(Example 3)
A 125 μm-thick acrylic film (S000 manufactured by Sumitomo Chemical Co., Ltd., Martens hardness 183 [N / mm ² ]) is used as a base material, and the hard coat agent (1) prepared above is applied to one side of the base material. After drying at 60 ° C. for 90 seconds, using an ultraviolet irradiation device (“F450” manufactured by Fusion UV Systems Japan Co., Ltd., lamp: 120 W / cm, H bulb) in an air atmosphere, the irradiation light quantity is 0.5 J / cm. ² was cured by irradiating with ultraviolet rays to form a hard coat layer having a thickness of 15 μm to obtain a hard coat film having a total thickness of 140 μm.

Example 4
Using a 125 μm thick acrylic film (HI50 manufactured by Kuraray Co., Ltd., Martens hardness 125 [N / mm ² ]) as a base material, the hard coat agent (1) prepared above was applied to one side of the base material. After drying at 60 ° C. for 90 seconds, using an ultraviolet irradiation device (“F450” manufactured by Fusion UV Systems Japan Co., Ltd., lamp: 120 W / cm, H bulb) in an air atmosphere, the irradiation light quantity is 0.5 J / cm ^2. Was cured by irradiating with ultraviolet rays to form a hard coat layer having a thickness of 15 μm to obtain a hard coat film having a total thickness of 140 μm.

(Example 5)
Using a 125 μm thick acrylic film (RT050 manufactured by Kuraray Co., Ltd., Martens hardness 138 [N / mm ² ]) as the base material, the hard coat agent (1) prepared above was applied to one side of the base material. After drying at 60 ° C. for 90 seconds, using an ultraviolet irradiation device (“F450” manufactured by Fusion UV Systems Japan Co., Ltd., lamp: 120 W / cm, H bulb) in an air atmosphere, the irradiation light quantity is 0.5 J / cm ^2. Was cured by irradiating with ultraviolet rays to form a hard coat layer having a thickness of 10 μm to obtain a hard coat film having a total thickness of 135 μm.

(Example 6)
Using a 125 μm thick acrylic film (RT050 manufactured by Kuraray Co., Ltd., Martens hardness 138 [N / mm ² ]) as the base material, the hard coat agent (1) prepared above was applied to one side of the base material. After drying at 60 ° C. for 90 seconds, using an ultraviolet irradiation device (“F450” manufactured by Fusion UV Systems Japan Co., Ltd., lamp: 120 W / cm, H bulb) in an air atmosphere, the irradiation light quantity is 0.5 J / cm ^2. Was cured by irradiating with ultraviolet rays to form a hard coat layer having a thickness of 20 μm to obtain a hard coat film having a total thickness of 145 μm.

(Example 7)
Using a 125 μm thick acrylic film (RT050 manufactured by Kuraray Co., Ltd., Martens hardness 138 [N / mm ² ]) as a base material, the hard coat agent (2) prepared above was applied to one side of the base material. After drying at 60 ° C. for 90 seconds, using an ultraviolet irradiation device (“F450” manufactured by Fusion UV Systems Japan Co., Ltd., lamp: 120 W / cm, H bulb) in an air atmosphere, the irradiation light quantity is 0.5 J / cm ^2. Was cured by irradiating with ultraviolet rays to form a hard coat layer having a thickness of 15 μm to obtain a hard coat film having a total thickness of 140 μm.

(Example 8)
Using a 125 μm thick acrylic film (RT050 manufactured by Kuraray Co., Ltd., Martens hardness 138 [N / mm ² ]) as the base material, the hard coat agent (1) prepared above was applied to one side of the base material. After drying at 60 ° C. for 90 seconds, using an ultraviolet irradiation device (“F450” manufactured by Fusion UV Systems Japan Co., Ltd., lamp: 120 W / cm, H bulb) in an air atmosphere, the irradiation light quantity is 0.5 J / cm ^2. Was cured by irradiating with ultraviolet rays to form a hard coat layer having a thickness of 15 μm. Next, the hard coating agent (3) prepared above was applied to the other surface of the acrylic film, dried at 60 ° C. for 90 seconds, and then irradiated with an ultraviolet irradiation device (“F450” manufactured by Fusion UV Systems Japan Co., Ltd.). ”, Lamp: 120 W / cm, H bulb), cured by irradiating with ultraviolet light at an irradiation light quantity of 0.5 J / cm ² to form a hard coat layer having a thickness of 10 μm and a double-sided hard having a total thickness of 150 μm A coated film was obtained.

(Comparative Example 1)
Using a 125 μm thick acrylic film (S001G manufactured by Sumitomo Chemical Co., Ltd., Martens hardness 113 [N / mm ² ]) as a base material, the hard coat agent (1) prepared above was applied to one side of the base material. After drying at 60 ° C. for 90 seconds, using an ultraviolet irradiation device (“F450” manufactured by Fusion UV Systems Japan Co., Ltd., lamp: 120 W / cm, H bulb) in an air atmosphere, the irradiation light quantity is 0.5 J / cm. ² was cured by irradiating with ultraviolet rays to form a hard coat layer having a thickness of 15 μm to obtain a hard coat film having a total thickness of 140 μm.

(Comparative Example 2)
Using a 125 μm thick acrylic film (S014G manufactured by Sumitomo Chemical Co., Ltd., Martens hardness 81 [N / mm ² ]) as a base material, the hard coat agent (1) prepared above was applied to one side of the base material. After drying at 60 ° C. for 90 seconds, using an ultraviolet irradiation device (“F450” manufactured by Fusion UV Systems Japan Co., Ltd., lamp: 120 W / cm, H bulb) in an air atmosphere, the irradiation light quantity is 0.5 J / cm. ² was cured by irradiating with ultraviolet rays to form a hard coat layer having a thickness of 15 μm to obtain a hard coat film having a total thickness of 140 μm.

(Comparative Example 3)
Using a 80 μm thick triacetylcellulose (TAC) film (TD80ULN manufactured by Fuji Film Co., Ltd., Martens hardness 65 [N / mm ² ]) as a base material, the hard coat agent prepared above is applied to one side of the base material. (1) is applied, dried at 60 ° C. for 90 seconds, and then irradiated with an ultraviolet ray irradiation device (“F450” manufactured by Fusion UV Systems Japan Co., Ltd., lamp: 120 W / cm, H bulb) in an air atmosphere. It hardened | cured by irradiating an ultraviolet-ray at 0.5 J / cm < ² >, the hard-coat layer of thickness 15 micrometers was formed, and the hard-coat film of total thickness 95 micrometers was obtained.

(Comparative Example 4)
Using a polycarbonate (PC) film having a thickness of 100 μm as a substrate (Iupilon manufactured by Mitsubishi Gas Chemical Company, Martens hardness 52 [N / mm ² ]), the hard coating agent prepared above is applied to one side of the substrate ( 1) is applied, dried at 60 ° C. for 90 seconds, and then irradiated with an ultraviolet ray irradiation device (“F450” manufactured by Fusion UV Systems Japan Co., Ltd., lamp: 120 W / cm, H bulb) in an air atmosphere. Curing was performed by irradiating ultraviolet rays at 5 J / cm ² to form a hard coat layer having a thickness of 15 μm to obtain a hard coat film having a total thickness of 115 μm.

(Comparative Example 5)
Using a polycarbonate (PC) film having a thickness of 100 μm as a base material (Panlite manufactured by Teijin Chemicals Ltd., Martens hardness 71 [N / mm ² ]), the hard coat agent prepared above on one side of the base material ( 1) is applied, dried at 60 ° C. for 90 seconds, and then irradiated with an ultraviolet ray irradiation device (“F450” manufactured by Fusion UV Systems Japan Co., Ltd., lamp: 120 W / cm, H bulb) in an air atmosphere. Curing was performed by irradiating ultraviolet rays at 5 J / cm ² to form a hard coat layer having a thickness of 15 μm to obtain a hard coat film having a total thickness of 115 μm.

(Comparative Example 6)
Using a polyethylene terephthalate (PET) film having a thickness of 125 μm (Lumirror U46 manufactured by Toray Industries Inc., Martens hardness 178 [N / mm ² ]) as a base material, on one side of the base material, the hard coat agent prepared above ( 1) is applied, dried at 60 ° C. for 90 seconds, and then irradiated with an ultraviolet ray irradiation device (“F450” manufactured by Fusion UV Systems Japan Co., Ltd., lamp: 120 W / cm, H bulb) in an air atmosphere. Curing was performed by irradiating ultraviolet rays at 5 J / cm ² to form a hard coat layer having a thickness of 15 μm to obtain a hard coat film having a total thickness of 140 μm.

  The following evaluation was performed about the hard coat film obtained by the said Example and comparative example. The results obtained are shown in the table below.

[Measurement of Martens hardness]
After pasting the resin films of the above-mentioned examples and comparative examples on a glass plate having a length of 150 mm and a width of 50 mm, a corner angle 136 is obtained using a FISCHERSCOPE / HM2000LT (manufactured by Fisher Instruments) in a 23 ° C. environment. The Vickers indenter at 0 ° was pushed with a load of 1 mN, and the Martens hardness was measured.

[Measurement of surface pencil hardness of hard coat film alone]
The hard coat films obtained in the above examples and comparative examples were cut into 10 cm squares, and the four corners were attached to a glass plate with a cellophane tape, and the surface pencil hardness was measured according to JIS K 5600-5-4 (1999 edition). Based on the regulations, the measurement was performed using a pencil scratch tester for coating film (load: 1 kg, manual type) manufactured by Imoto Seisakusho Co., Ltd.

[Measurement of surface pencil hardness after sticking adhesive sheet]
The hard coat films obtained in the above examples and comparative examples were cut into 10 cm squares, and a DIC adhesive sheet ZB7010W-15 (thickness 15 μm) was bonded to the surface opposite to the surface hard coat layer of the film, and then glass The surface pencil hardness affixed to the board is measured using a pencil scratch tester for coating film (load: 1 kg, manual type) manufactured by Imoto Seisakusho Co., Ltd. based on the provisions of JIS K 5600-5-4 (1999 edition). It was measured.

[Evaluation of interference fringes]
LSRW55White manufactured by DIC was attached to the back surface of the hard coat film obtained in the above Examples and Comparative Examples so that no bubbles would enter, and the interference fringes were visually observed under a three-wavelength fluorescent lamp.
○: Interference fringes are hardly seen.
X: Interference fringes are observed.

[Fingerprint wiping properties]
The fingerprint of the index finger was attached to the surface of the hard coat film obtained in the above Examples and Comparative Examples. Thereafter, the fingerprint was wiped off with Bencott S-2 (manufactured by Asahi Kasei Fibers Co., Ltd.), and the number of times the fingerprint was wiped until it could no longer be seen was measured. Judgment criteria are as follows.
○: Number of wipes 1 to 15 times ×: Number of wipes 16 times or more

[Measurement of total light transmittance]
The hard coat films obtained in the above examples and comparative examples were attached to a glass plate having a thickness of 0.5 mm, a length of 50 mm, and a width of 40 mm, and then heated under conditions of 5 atm, 50 ° C., and 20 minutes. Fixed by pressure treatment. The total light transmittance was measured based on JIS K7105 and JIS K7136 of the sample using “HR-100 type” manufactured by Murakami Color Research Laboratory.

As in Examples 1 to 8, the hard coat film using an acrylic resin film having a Martens hardness of 120 N / mm ² or more as a base material had a pencil hardness of 4H. On the other hand, as in Comparative Examples 1 and 2, when an acrylic resin film of less than 120 N / mm ² was used as the substrate, the surface hardness was H or less. Moreover, also when using a TAC film or a polycarbonate film as a base material as Comparative Examples 3-5, the surface hardness was H or less. Furthermore, as in Comparative Example 6, the hard coat film used as a PET film substrate having a Martens hardness of 120 N / mm ² or more had a pencil hardness of 2H, and interference fringes were observed.

Claims (12)

A hard coat film having a hard coat layer on at least one surface of a film substrate, wherein the film substrate has a Martens hardness measured by pressing a Vickers indenter with an edge angle of 136 ° into the surface at a load of 1 mN. A hard coat film characterized by being an acrylic resin film substrate of mm ² or more.   The hard coat film according to claim 1, wherein the total thickness is 200 μm or less.   The hard coat film according to claim 1 or 2, wherein the film substrate has a thickness of 150 µm or less.   The hard coat film according to any one of claims 1 to 3, wherein the film substrate has a total light transmittance of 85% or more.   The hard coat film according to any one of claims 1 to 4, wherein a difference in refractive index between the hard coat layer and the film substrate is less than 0.1.   The hard coat film according to claim 1, wherein the hard coat layer has a refractive index of 1.45 to 1.55.   7. The acrylic resin film substrate according to claim 1, wherein the film base material is an acrylic resin film base material having an indentation elastic modulus of 2000 MPa or more measured by pushing a Vickers indenter with a ridge angle of 136 ° into the surface with a load of 1 mN. Hard coat film.   The hard coat film according to any one of claims 1 to 7, wherein the hard coat layer is a hard coat layer having a surface hardness of 3H or more when applied to glass with a thickness of 10 µm.   A decorative film comprising a decorative layer on one surface of the hard coat film according to claim 1.   A protective film comprising an adhesive layer on one side of the hard coat film according to claim 1.   The protective film according to claim 10, wherein the pressure-sensitive adhesive layer has a thickness of 5 to 50 μm.   The protective film of Claim 10 or 11 used for protection of the image display part of a portable electronic terminal.