JP2006058574A - Hard coat film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hard coat film excellent in the occurrence of curling and cracking and scratch resistance.
SOLUTION: A hard coat film 10 of the present invention is formed by laminating a first hard coat layer 2 containing a curable epoxy acrylate on a plastic substrate 1, and curable urethane acrylate on the first hard coat layer 2. The second hard coat layer 3 containing is laminated. The universal hardness of the second hard coat layer 3 is preferably larger than the universal hardness of the first hard cord layer 2.
[Selection] Figure 1

Description

  The present invention relates to a hard coat film.

  A transparent plastic film having scratch resistance and scratch resistance is generally attached to the surface of optical members such as liquid crystal display devices, CRT (CRT) display devices, lenses, mirrors, goggles and the like. Yes. In addition, a plastic film may be attached to a glass product to prevent the glass from scattering. However, when the hardness of the surface of such a plastic film is insufficient, a hard coat layer is usually formed on the surface.

  In general, as a technique for forming a hard coat layer for hardening a plastic surface, for example, a metal thin film is formed by a method of coating a curable resin such as an organosiloxane or a melamine, a vacuum deposition method, a sputtering method, or the like. And a method of coating a polyfunctional acrylate-based active energy ray-curable resin. Among these methods, in recent years, a method using an active energy ray-curable resin has been widely adopted because it is easy to process a large area and is excellent in productivity.

  However, in any of these methods, the adhesion between the hard coat layer and the plastic substrate, the occurrence of cracks or curling when the film is folded, etc. can be realized within a practically acceptable range. However, since the pencil hardness value of the hard coat layer on the plastic substrate is 2H to 3H, there may be a problem in terms of scratch resistance and scratch resistance, for example.

  When the hardness of the hard coat layer is insufficient as described above, for example, the hardness is improved simply by making the hard coat layer thicker than a normal thickness (for example, 3 μm to 15 μm). It is possible to solve the problem. However, increasing the thickness of the hard coat layer simultaneously causes the following problems. That is, cracks and peeling of the hard coat layer are likely to occur, and there is also a problem that the hard coat layer to be formed contracts and a large curl is generated by curing the resin as described above.

On the other hand, specific examples of conventional hard coat films in which a hard coat layer is laminated on a plastic substrate include the following. For example, a hard coat film in which a hard coat layer is laminated on a plastic substrate via a buffer layer (see, for example, Patent Document 1), a hard coat layer having a two-layer structure, and a radical curable resin and a lower layer A hard coat film including a hard coat layer using a cured resin layer made of a blend with a cationic curable resin and using a cured resin layer made only of a radical curable resin as an upper layer (see, for example, Patent Document 2) is disclosed. Has been. Furthermore, a hard coat film (for example, Patent Document 3) including a laminated hard coat layer in which the upper layer has a higher universal hardness than the lower layer is disclosed.
JP-A-11-300873 JP 2000-71392 A JP 2002-36436 A

  However, it has been difficult for these hard coat films to satisfy, for example, adhesion, curl suppression, crack resistance, hardness, scratch resistance, and scratch resistance within a practically acceptable range.

  Accordingly, the present invention provides a hard coat film in which a hard coat layer is formed on a plastic substrate, and the adhesion between them and the occurrence of curling and cracking are within a practically acceptable range and are scratch resistant. The purpose of the present invention is to provide a hard coat film having excellent properties and scratch resistance.

  In order to achieve the object, the present invention includes a plastic substrate, a first hard coat layer, and a second hard coat layer, and the second hard coat layer is disposed on the plastic substrate via the first hard coat layer. A hard coat layer is laminated, the first hard coat layer includes a curable epoxy acrylate, and the second hard coat layer includes a curable urethane acrylate.

  The inventors of the present invention have made extensive studies to improve the mechanical properties of the hard coat layer. As a result, by providing a first hard coat layer containing a curable epoxy acrylate on a plastic substrate and a second hard coat layer containing a curable urethane acrylate on the first hard coat layer, curling and The present inventors have found that a hard coat film that achieves a practically acceptable state with respect to generation of cracks during bending and adhesion between layers can be obtained, and is excellent in scratch resistance and scratch resistance.

  Specifically, although epoxy acrylate has a relatively medium hardness, it undergoes ring-opening polymerization, and therefore shrinkage due to curing is extremely small, so curling is unlikely to occur and flexibility is also good. Therefore, it is difficult for cracks to occur. On the other hand, urethane acrylate is extremely excellent in hardness since it is a polyfunctional type, although curing shrinkage occurs. Therefore, for the first hard coat layer on the plastic substrate, first, a curable epoxy acrylate that hardly causes curling or cracking is used, while the second hard coat layer on the surface formed on the first hard coat layer is used. If urethane acrylate having a relatively high hardness was used for the coat layer, the above-described effects could be achieved due to the respective properties of both. The hard coat film of the present invention having improved mechanical properties in a wide range of items is useful for various optical applications, for example, as a hard coat film for antireflection or in combination with a polarizing plate.

  In the hard coat film of the present invention, the universal hardness of the second hard coat layer is preferably larger than the universal hardness of the first hard cord layer. As described above, this requirement can usually be satisfied by using epoxy acrylate for the first hard coat layer and urethane acrylate for the second hard coat layer.

The universal hardness of the first hard coat layer, for example, a ^{200N / mm 2 ~300N / mm 2} , preferably ^{210N / mm 2 ~290N / mm 2} , more preferably, 220N / mm ² ~280N / mm ² . If the hardness is 200 N / mm ² or more, sufficient hardness can be imparted to the hard coat film of the present invention, and if the hardness is 300 N / mm ² or less, the hard coat film of the present invention has good flexibility. It can be applied and the occurrence of curling and cracking can be sufficiently suppressed.

Meanwhile, the universal hardness of the second hard coat layer is preferably larger than the universal hardness of the first hard coat layer as described above, for example, a ^{250N / mm 2 ~350N / mm 2} , 260N / preferably mm ² ~340N / mm ^2, more preferably ^{270N / mm 2 ~330N / mm 2} . If the hardness is 250 N / mm ² or more, sufficient hardness can be imparted to the hard coat film of the present invention, and if the hardness is 350 N / mm ² or less, brittleness can be sufficiently suppressed, and the hard coat of the present invention. The better flexibility of the film can be maintained.

The difference in universal hardness between the first hard coat layer and the second hard coat layer is preferably 20 N / mm ² or more, for example.

  The universal hardness in this invention can be calculated | required, for example using a micro surface hardness tester. Specifically, a diamond pyramid indenter (tip facing angle 136 °) is used, a test load is applied to the square pyramid indenter, and the tip is pressed against the sample surface. Then, the depth of indentation by the tip of the square pyramid indenter under the load is measured, the surface area of the indentation caused by the test load is calculated from the geometric shape of the indenter, and the test load value Is the universal hardness. Examples of the micro surface hardness tester include trade name Fisherscope H100C (manufactured by Fisher Instruments).

  Although the hardening form of the curable epoxy acrylate contained in the first hard coat layer is not particularly limited, for example, a photo-curing type such as ultraviolet curing is common.

  The curable epoxy acrylate can be obtained, for example, by a conventionally known method. For example, the curable epoxy acrylate can be synthesized by reacting an epoxy resin with acrylic acid or methacrylic acid. The curable epoxy acrylate may be a commercially available one.

  The epoxy resin is not particularly limited, and examples thereof include a bisphenol type epoxy resin, a novolac type epoxy resin, a polyfunctional glycidylamine type resin, a polyfunctional glycidyl ether type epoxy resin, and a brominated epoxy resin. Examples of the bisphenol type epoxy resin include bisphenol A type diglycidyl ether, bisphenol F type diglycidyl ether, bisphenol S type diglycidyl ether, and hexahydrobisphenol A type diglycidyl ether. Examples of the novolac type epoxy resin include phenol novolac type epoxy resin, orthogresol novolak type epoxy resin, and the like. Examples of the polyfunctional glycidylamine type epoxy resin include triglycidyl-p-aminophenol, triglycidyl isocyanurate, tetraglycidylmetaxylenediamine, tetraglycidyldiaminofiphenylmethane, tetraglycidyl-1,3-bisaminomethylsilrohexane. Etc. Examples of the polyfunctional glycidyl ether type epoxy resin include tetraphenyl glycidyl ether ethane, triphenyl glycidyl ether methane, 4,4′-bis (2,3-epoxypropoxy) -3,3 ′, 5,5′-tetramethyl. Biphenyl and the like can be mentioned. Examples of the brominated epoxy resin include brominated bilphenol A type epoxy resin and brominated phenol novolac type epoxy resin. These epoxy resins may be used alone or in combination of two or more.

  The thickness of the first hard coat layer is, for example, 3 μm to 20 μm, preferably 5 μm to 15 μm.

The refractive index of the first hard coat layer is not particularly limited, but is, for example, 1.46 to 1.53, and preferably 1.47 to 1.50. The refractive index can be measured using, for example, a refractometer, and the refractometer is not particularly limited, and examples thereof include an Abbe refractometer (manufactured by Atago Co., Ltd.). Further, in order to suppress interference unevenness in the hard coat film of the present invention, the difference between the refractive index of the first hard coat layer and the refractive index of the plastic substrate is preferably small, more preferably substantially the same. Although the hardening form of the curable urethane acrylate contained in the second hard coat layer is not particularly limited, for example, a photo-curing type such as ultraviolet curing is common.

  The curable urethane acrylate can be obtained by a conventionally known method. For example, the curable urethane acrylate can be synthesized by reacting a terminal isocyanate prepolymer obtained from a polyol compound and an isocyanate compound with an acrylate having a hydroxyl group. The curable urethane acrylate may be a commercially available product.

  Examples of the polyol compound include polyether-based polyols, polyester-based polyols, copolymers of acrylic acid esters and hydroxyethyl (meth) acrylate, and the like. Examples of the polyether-based polyol include polyoxytetramethylene glycol. Examples of the polyester polyol include polyadipate polyol and polycarbonate polyol.

  Examples of the isocyanate compound include adducts of methylene bis (p-phenylene diisocyanate), hexamethylene diisocyanate / hexanetriol, hexamethylene diisocyanate, tolylene diisocyanate, tolylene diisocyanate trimethylolpropane, and 1,5-naphthylene diene. Examples thereof include isocyanate, thiopropyl diisocyanate, ethylbenzene-2,4-diisocyanate, 2,4-tolylene diisocyanate dimer, hydrogenated xylylene diisocyanate, tris (4-phenylisocyanate) neophosphate.

  Examples of the acrylate include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2 ethylhexyl (meth) acrylate, methoxyethyl (meth) acrylate, butoxyethyl (meth) acrylate, and phenyl (meth). Examples include acrylates. Further, by using the acrylate polyfunctional monomer in combination, it is possible to further impart hardness to the hard coat layer. Examples of the polyfunctional monomer include trimethylolpropane tri (meth) acrylate, hexanediol (meth) acrylate, tripropylene glycol (meth) acrylate, diethylene glycol di (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (Meth) acrylate, 1,6-hexanediol (meth) acrylate, neopentyl glycol di (meth) acrylate and the like.

  The thickness of the second hard coat layer is, for example, 3 μm to 20 μm, preferably 5 μm to 15 μm. The difference in thickness between the first hard coat layer and the second hard coat layer is preferably substantially the same.

  The refractive index of the second hard coat layer is not particularly limited, and is, for example, 1.46 to 1.53, preferably 1.47 to 1.50. The refractive index can be measured using a refractometer, for example, as described above. Further, in order to suppress interference unevenness in the hard coat film of the present invention, the difference between the refractive index of the second hard coat layer and the refractive index of the plastic substrate is preferably small, more preferably substantially the same. is there.

  Although it does not restrict | limit especially as said plastic base material, For example, the base material which is high in the light transmittance of visible light, and is excellent in transparency is preferable. A material having a small birefringence is also preferable as the material for the plastic substrate. The visible light transmittance of the plastic substrate is preferably 90% or more, for example, and the haze value of the plastic substrate is preferably 1% or less.

  Examples of the material for the plastic substrate include polyester polymers, cellulose polymers, polycarbonate polymers, acrylic polymers, styrene polymers, olefin polymers, vinyl chloride polymers, amide polymers, and the like. Examples of the polyester polymer include polyethylene terephthalate and polyethylene naphthalate. Examples of the cellulose polymer include diacetyl cellulose and triacetyl cellulose (TAC). Examples of the acrylic polymer include polymethyl methacrylate. Examples of the styrenic polymer include polystyrene, acrylonitrile / styrene copolymer, and the like. Examples of the olefin polymer include polyethylene, polypropylene, polyolefin having a cyclic or norbornene structure, and an ethylene / propylene copolymer. Examples of the amide polymer include nylon and aromatic polyamide. Other examples of the plastic substrate material include imide polymers, sulfone polymers, polyether sulfone polymers, polyether ether ketone polymers, polyphenylene sulfide polymers, vinyl alcohol polymers, and vinylidene chloride polymers. Vinyl butyral polymer, arylate polymer, polyoxymethylene polymer, and epoxy polymer. It is also possible to use blends of these polymer materials.

  In addition, as will be described later, when the hard coat film of the present invention is used as a protective film for a polarizing plate, the material of the plastic substrate is made of cellulose polymer such as triacetyl cellulose, polycarbonate polymer, acrylic polymer, cyclic Alternatively, a polyolefin having a norbornene structure is preferable.

  The thickness of the plastic substrate is not particularly limited, but is, for example, about 10 μm to 500 μm, preferably 20 μm to 300 μm, more preferably 30 μm to 200 μm, from the viewpoints of workability such as strength and handling, and thin layer properties. It is. The refractive index of the plastic substrate is not particularly limited, and is, for example, 1.30 to 1.80.

  An example of the hard coat film of the present invention will be described with reference to FIG. FIG. 1 is a cross-sectional view showing a schematic configuration of a hard coat film. As illustrated, the hard coat film 10 has a second hard coat layer 3 laminated on a plastic substrate 1 with a first hard coat layer 2 interposed therebetween.

  Below, the manufacturing method of the hard coat film of this invention is demonstrated. The production method is not particularly limited. For example, the hard coat film of the present invention is formed by forming the first hard coat layer on the plastic substrate and further forming the second hard cord layer thereon. Is obtained.

The first hard coat layer can be formed by, for example, applying the curable epoxy acrylate on the plastic substrate and subjecting the coating film to a curing treatment of the curable epoxy acrylate. For coating, for example, a coating solution in which epoxy acrylate is dissolved in a solvent can be used. The solvent is not particularly limited, and examples thereof include ketone-based, alcohol-based, and ester-based organic solvents. For example, a polymerization initiator such as a photopolymerization initiator may be added to the coating liquid.

  The photopolymerization initiator is not particularly limited, and conventionally known photopolymerization initiators can be used. For example, acetophenones, benzophenones, Michler's ketone, benzoylbenzoate, benzoins, α-acyloxime ester, tetramethylthiuram monosulfide And thioxanthone can be used. One type of these photopolymerization initiators may be used, or two or more types may be used in combination. The amount of the photopolymerization initiator added is preferably, for example, in the range of 0.1 to 15 parts by weight, more preferably in the range of 1 to 10 parts by weight with respect to 100 parts by weight of the epoxy acrylate before curing. is there. In addition to the photopolymerization initiator, a photosensitizer can also be used. The photosensitizer is not particularly limited, and conventionally known photosensitizers can be used, and examples thereof include n-butylamine, triethylamine, tri-n-butylphosphine, and thioxanthone.

  The coating liquid may further contain conventionally known additives such as inorganic fine particles, organic fine particles, leveling agents, thixotropic agents, and antistatic agents. By adding the inorganic or organic fine particles to the coating liquid, the universal hardness of the hard coat layer can be adjusted, and for example, shrinkage due to crosslinking can be improved.

  The solid content of the coating liquid is not particularly limited. For example, since the viscosity is easy to apply, it is preferably, for example, 0.5 to 80% by weight with respect to the total amount of the coating liquid. More preferably, it is 10-60 weight%, More preferably, it is 20-50 weight%.

  The coating method is not particularly limited, and examples thereof include a roll coating method, a spin coating method, a wire bar method, a dip coating method, an extrusion method, a curtain coating method, a spray coating method, a casting film forming method, and a bar coating. Method, gravure coating method, etc. can be adopted.

The said hardening process should just be performed according to the hardening form of the epoxy acrylate to be used, for example, light irradiation processes, such as ultraviolet irradiation. The ultraviolet irradiation conditions can be appropriately determined according to, for example, the type of the epoxy acrylate, but the integrated light quantity of the ultraviolet irradiation is, for example, 50 to 1000 mJ / cm ² , preferably 100 to 600 mJ / cm ² . Preferably it is 200-400 mJ / cm < ² >. Moreover, ultraviolet irradiation time is 1 second-1 minute, for example, Preferably it is 2 to 40 second, More preferably, it is 3 to 30 second.

  Moreover, after forming the said coating film by coating, you may give it before a hardening process. Although the temperature of a drying process can be suitably determined according to the kind etc. of the said epoxy acrylate, it is 50 to 150 degreeC, for example, Preferably it is 60 to 120 degreeC. The drying may be performed at a constant temperature or may be performed while increasing or decreasing the temperature stepwise. The drying time is not particularly limited, but is, for example, 10 seconds to 10 minutes, and preferably 30 seconds to 3 minutes.

  Subsequently, a second hard coat layer containing a curable urethane acrylate is provided on the surface of the first hard coat layer formed on the plastic substrate. The method for forming the second hard coat layer is not particularly limited. For example, the method is the same as the method for forming the first hard coat layer except that curable urethane acrylate is used instead of curable epoxy acrylate. Can do.

  The hard coat film of the present invention may further include an antireflection layer. Thus, the hard coat film further including an antireflection layer is useful as, for example, an antireflection hard coat film (hereinafter referred to as “antireflection hard coat film”).

  The antireflection layer is preferably laminated, for example, on a second hard cord layer laminated on the plastic substrate via a first hard coat layer.

  The antireflection layer preferably includes a low refractive index layer having a refractive index lower than that of the second hard coat layer. The antireflection layer may be composed of only the low refractive index layer, or may be a laminate that further includes other layers. When the antireflection layer is a laminate, the low refractive index layer is preferably disposed so as to be the outermost layer of the antireflection hard coat film.

  In this case, the refractive index of the low refractive index layer is, for example, 1.30 to 1.50, and is preferably 1.45 or less in order to further suppress the reflectance. The refractive index of the low refractive index phase is preferably lower than any of the refractive indexes of the plastic substrate, the first hard coat layer, and the second hard coat layer.

  With respect to the hard coat film of the present invention, an example of the antireflection hard coat film in which the antireflection layer comprises only the low refractive index layer will be described with reference to FIG. FIG. 2 is a cross-sectional view schematically showing the antireflection hard coat film. In the figure, the same parts as those in FIG. As shown in FIG. 2, the anti-reflective hard coat film 20 has the second hard coat layer 3 laminated on the plastic substrate 1 with the first hard coat layer 2 interposed therebetween, and on the second hard coat layer, Further, an antireflection layer (single layer low refractive index layer) 4 is laminated.

The material for forming the low refractive index layer is not limited as long as the refractive index is lower than the refractive index of the second hard coat layer, but a sol-gel material is preferable. Examples of the sol-gel material include those using a metal alkoxide, preferably a sol-gel material containing a metal alkoxide and a silane coupling agent having a fluoroalkyl group. Examples of the metal alkoxide include tetraethoxysilane. In addition to this, for example, a resin-based material such as an ultraviolet curable acrylic resin, or a hybrid material in which inorganic fine particles such as colloidal silica are dispersed in the resin can be used. Among these, those containing a fluorine group as described above are preferable from the viewpoint of imparting antifouling properties to the surface of the low refractive layer, and it is preferable that the content of the inorganic component is large from the viewpoint of scratch resistance. Specifically, a sol-gel material containing a siloxane oligomer or a silane coupling agent having a fluoroalkyl group is preferable. Examples of the silane coupling agent having a fluorine group include perfluoroalkylalkoxysilanes, and specific examples include compounds represented by the following general formula (1). In the following general formula, R represents an alkyl group having 1 to 5 carbon atoms, and n is an integer of 0 to 12. Specific examples of the compound represented by the following general formula include, for example, trifluoropropyltrimethoxysilane, trifluoropropyltriethoxysilane, tridecafluorooctyltrimethoxysilane, tridecafluorooctyltriethoxysilane, heptadecafluorodecyl. Examples include trimethoxysilane and heptadecafluorodecyltriethoxysilane. Among these, for example, compounds in which n is 2 to 6 are preferable.
CF ₃ (CF ₂ ) _n CH ₂ CH ₂ Si (OR) ₃ (1)
Examples of silane compounds that are silane coupling agents include γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N- (β-aminoethyl) -γ-aminopropyltrimethoxysilane, N- ( Silane coupling agents such as β-aminoethyl) -γ-aminopropyltriethoxysilane and N- (β-aminoethyl) -γ-aminopropylmethyldimethoxysilane can be mentioned.

  As a material for forming the low refractive index layer, a functional group having a positive charge and a compound having a functional group capable of being positively charged may be used in combination. By using these compounds in combination to form a low refractive index layer, for example, the outermost surface of the antireflection layer can be apparently electrically neutralized, and the charging of the outermost surface is reduced, and dust, dust, It is possible to further reduce the adhesiveness such as, and improve the drawability. Conventionally known compounds can be used as the positively charged functional group and the compound having a positively chargeable functional group. Specific examples of the functional group include functional groups containing nitrogen atoms such as an amino group and an ammonium base. Group, a functional group containing a phosphorus atom such as a phosphate group, and a functional group containing a sulfur atom such as a sulfonium group. Among them, a functional group containing a nitrogen atom such as an amino group or an ammonium base is preferable in terms of preventing adhesion of dust and dust and wiping off as described above. Examples of the compound having a functional group containing a nitrogen atom include quaternary ammonium salts such as polyethyleneimine, tetrabutylammonium bromide, and tetraammonium chloride.

  The thickness of the low refractive index layer is not particularly limited, and is, for example, 0.05 μm to 0.3 μm, preferably 0.1 μm to 0.3 μm. From the viewpoint of reducing the reflectance, the set value of the phase difference of the low refractive index layer is, for example, 120 nm to 160 nm, preferably 130 nm to 150 nm, and more preferably 140 nm.

  The formation of the low refractive index layer is not particularly limited, and can be performed by a conventionally known method. In the present invention, for example, when a low refractive index layer is directly formed on the second hard coat layer, a coating liquid containing a low refractive index layer forming material is applied onto the second hard coat layer. The low refractive index layer can also be formed by drying and curing the formed coating film.

  Prior to the formation of the low refractive index layer, the surface of the second hard coat layer may be subjected to surface modification treatment. Examples of the surface modification treatment include discharge and radiation irradiation treatment, and thereby, for example, increase the adhesion between the second hard coat layer and the low refractive index layer to be formed, and improve chemical resistance. Can be made. Examples of the discharge / radiation irradiation treatment include corona discharge treatment, plasma treatment, ultraviolet irradiation treatment, electron beam irradiation treatment, etc. Among them, corona discharge treatment and ultraviolet irradiation treatment are preferable.

  In general, the coating solution for the low refractive index layer can be prepared by dissolving the above-described forming material in a suitable solvent. The kind of solvent can be suitably determined according to the kind of forming material to be used, for example. For example, when the fluorine-containing compound and the compound having a functional group are used in combination, the mixing ratio of both is not particularly limited, but for example, the functional group has 1 functional part with respect to 1 mol part of the fluorine-containing compound. The compounding ratio of the compound is about 0.1 to 1.5 mol parts, preferably 0.5 to 1 mol parts. When the compounding ratio of the compound having a functional group is small, the antifouling property relating to the property of repelling liquid is good, but it is difficult to sufficiently exhibit the anti-adhesion property and extractability of dust, dust, etc.・ Prevents adherence and removal of dust, etc., but tends to reduce contamination resistance. Further, for example, a sol in which silica, alumina, titania, zirconia, magnesium fluoride, ceria, etc. are dispersed in a solvent such as alcohol may be added to the coating solution. In addition, additives such as metal salts and metal compounds can be appropriately blended.

  The method for coating the coating liquid on the second hard coat layer is not particularly limited. For example, the doctor blade method, the gravure roll coater method, the dipping method, the spin coating method, and the brush coating method as described above. Conventionally known methods such as a flexographic printing method and a die coater method can be employed. Moreover, the conditions of the drying treatment / curing treatment for the formed coating film are not particularly limited, and the treatment temperature is, for example, 60 ° C. to 150 ° C., preferably 70 ° C. to 130 ° C., and the treatment time is, for example, 100 It is less than time and 0.5 hour-10 hours are preferable. Heating can be performed using, for example, a hot plate, an oven, a belt furnace, or the like.

  Next, the polarizing plate with a hard coat film of the present invention will be described. The polarizing plate with a hard coat film of the present invention includes the above-described hard coat film of the present invention and a polarizing plate. Moreover, it is preferable that the said polarizing plate is laminated | stacked on the side in which the hard-coat layer of the plastic base material in the said hard-coat film is not formed. The polarizing plate with a hard coat film having such a configuration is particularly useful as a polarizing plate with a hard coat film for antireflection (an antireflection polarizing plate). In the present invention, the polarizing plate may be, for example, only a polarizer, or a transparent protective film laminated on one or both surfaces of the polarizer.

  The polarizing plate with a hard coat film of the present invention will be described with reference to the sectional view of FIG. In the figure, the same parts as those in FIG. As shown in the figure, the anti-reflection polarizing plate 30 includes the first hard coat layer 2, the second hard coat layer 3 and the low refractive index layer 4 laminated on the plastic substrate 1 in this order. The polarizing plate 7 is laminated | stacked on the plastic substrate 1 side of the anti-reflective hard coat film 20 including the anti-reflective hard coat film 20 and the polarizing plate 7 by which the transparent protective film was laminated | stacked on both surfaces of the polarizer.

  In the polarizing plate with a hard coat film of the present invention, the plastic substrate of the hard coat film can also serve as the transparent protective film of the polarizing plate. An example of such a polarizing plate with a heart code film will be described with reference to the cross-sectional view of FIG. In the figure, the same parts as those in FIG. As shown in the figure, a polarizing plate 40 with a hard coat film includes the above-described antireflection hard coat film 20 and a polarizing plate 8 in which a transparent protective film is disposed on one side of a polarizer 5, and includes an antireflection hard coat. The plastic substrate 1 of the film 20 and the polarizer 5 are laminated so as to face each other.

  The polarizing plate used in the present invention is not particularly limited, and a conventionally known polarizing plate can be used. As described above, only the polarizer may be used, but usually a transparent protective film is laminated on at least one of the polarizers. What you have is common.

  The polarizer is not particularly limited, and for example, various films are adsorbed and dyed with dichroic substances such as iodine and dichroic dyes, stretched, cross-linked, dried, and the like by a conventionally known method. Can be prepared. Among them, a polarizer that transmits linearly polarized light when natural light is incident and has excellent light transmittance and degree of polarization is preferable. Examples of the various films for adsorbing the dichroic substance include PVA films such as polyvinyl alcohol (PVA), partially formalized PVA films, ethylene / vinyl acetate copolymer partially saponified films, and cellulose films. And a highly hydrophilic film. In addition to this, for example, a polyene oriented film such as a dehydrated PVA product or a dehydrochlorination treatment of polyvinyl chloride can be used. Among these, as the film, a PVA film is preferable. The thickness of the polarizer is generally 1 to 80 μm, but is not limited thereto.

  The material for the transparent protective film is not particularly limited, but a polymer film that is excellent in transparency, mechanical strength, thermal stability, moisture shielding properties, and the like is preferable. Examples of the polymer include acetate resin, polyester resin, polyethersulfone resin, polycarbonate resin, polyamide resin, polyimide resin, polynorbornene resin, polyolefin resin, acrylic resin, and a substituted imide group or an unsubstituted imide group in the side chain. Examples thereof include a mixture of a thermoplastic resin and a thermoplastic resin having a substituted phenyl group or an unsubstituted phenyl group and a nitrile group in the side chain. Specific examples of the acetate resin include triacetyl cellulose, and specific examples of the thermoplastic resin mixture include isobutene and N-methylmaleimide described in JP-A-2001-343529 (WO01 / 37007). And a resin composition containing an alternating copolymer of acrylonitrile / styrene copolymer. A triacetyl cellulose film whose surface is saponified with an alkali or the like is preferable from the viewpoint of polarization characteristics and durability. Although it does not restrict | limit especially as thickness of the said transparent protective film, Usually, 500 micrometers or less are preferable from points, such as thickness reduction of a polarizing plate, More preferably, it is 5-300 micrometers, More preferably, it is 5-150 micrometers.

  The lamination method of the polarizer and the transparent protective film or the hard coat film of the present invention is not particularly limited, and can be performed by a conventionally known method. Generally, it is performed using a pressure-sensitive adhesive, an adhesive, or the like, and the type of the pressure-sensitive adhesive (pressure-sensitive adhesive) or the adhesive to be used is appropriately determined according to, for example, the material of the film to be laminated. it can. Examples of the adhesive include, for example, polymer pressure sensitive adhesives such as acrylic, vinyl alcohol, silicone, polyester, polyurethane, and polyether, and rubber pressure sensitive adhesives. Further, an adhesive composed of a water-soluble crosslinking agent of vinyl alcohol polymers such as glutaraldehyde, melamine and oxalic acid can be used. Among these pressure-sensitive adhesives and adhesives, for example, those that do not easily peel off under the influence of temperature or heat and that are excellent in light transmittance and degree of polarization are preferable. Specifically, when the polarizer is a PVA-based film, for example, a PVA-based adhesive is preferable for reasons such as the stability of the adhesive treatment. For example, the pressure-sensitive adhesive or adhesive may be applied to the surface of a member to be bonded (for example, the transparent protective film or the like), or a tape or sheet made of the pressure-sensitive adhesive or adhesive. Layers may be placed between the members to be bonded.

  The polarizing plate with a hard coat film of the present invention may be further subjected to surface treatment such as anti-sticking treatment, diffusion treatment, and anti-glare treatment. The anti-sticking treatment is for the purpose of preventing adhesion to an adjacent layer, the diffusion treatment is for the purpose of diffusing the light transmitted through the polarizing plate to enlarge the viewing angle and compensating the viewing angle, and the anti-glare treatment is for polarizing plate It is intended to prevent the outside light from being reflected on the surface of the light and hindering the viewing of the light transmitted through the polarizing plate. These treatments can be performed, for example, by forming a fine concavo-convex structure on the surface of the second hard coat layer or the low refractive index layer. Examples of a method for forming such a concavo-convex structure include a roughening method such as a sand blast method and an embossing method, and a method of blending transparent fine particles into the material of the transparent protective film as described above.

  The polarizing plate with a hard coat film of the present invention may further be combined with other optical members. Examples of the other optical member include a diffusion control film and a brightness enhancement film. As the diffusion control film, for example, a film using diffusion, scattering, refraction, etc. to control the viewing angle, and a diffusion, scattering, refraction, etc. were used to control glare or scattered light related to resolution, etc. Examples include films. As the brightness enhancement film, for example, a brightness enhancement film using selective reflection of cholesteric liquid crystal and a λ / 4 plate, a scattering film using anisotropic scattering by the polarization direction, or the like can be used. Moreover, you may use in combination with a wire grid type polarizer. Furthermore, it may be a dielectric multilayer thin film or a multilayer laminate of thin film films having different refractive index anisotropies. For example, trade name “D-BEF” manufactured by 3M Co. can be used. Moreover, you may use a reflection sheet, various phase difference plates, etc. as said optical member. By using such an optical member, the polarizing plate with a hard coat film of the present invention can be, for example, a reflective (elliptical) polarizing plate or a transflective (elliptical) polarizing plate.

  Thus, when laminating | stacking 2 or more types of optical members, the polarizing plate with a hard-coat film of this invention can be formed also by the system laminated | stacked separately sequentially, for example in the manufacture process of a liquid crystal display device etc. However, if these optical members are laminated in advance, there are advantages that, for example, quality stability and assembly workability are excellent, and manufacturing efficiency of a liquid crystal display device and the like can be improved.

  The polarizing plate with a hard coat film of the present invention preferably has a pressure-sensitive adhesive layer or an adhesive layer in the outermost layer because it can be easily laminated to other members such as a liquid crystal cell. The arrangement of the pressure-sensitive adhesive layer may be only one of the outermost layers or may be both surfaces. The material of the pressure-sensitive adhesive layer is not particularly limited, and a conventionally known material such as an acrylic polymer can be used. In particular, foaming due to moisture absorption and prevention of peeling, a decrease in optical characteristics due to a difference in thermal expansion, and a liquid crystal cell In view of the ability to form a liquid crystal display device that is free from warpage and thus has high quality and excellent durability, for example, a material having a low moisture absorption rate and excellent heat resistance is preferable. Moreover, the adhesive layer etc. which contain microparticles | fine-particles and show light diffusibility may be sufficient. Formation of the pressure-sensitive adhesive layer in the polarizing plate is, for example, a method of forming a layer by directly adding a solution or melt of various pressure-sensitive adhesive materials to a predetermined surface by a development method such as casting or coating. Similarly, a pressure sensitive adhesive layer can be formed on a separator, which will be described later, and transferred to a predetermined surface of the polarizing plate. When the surface of the pressure-sensitive adhesive layer or the like is exposed, it is preferable to cover the surface with a separator for the purpose of preventing contamination until the pressure-sensitive adhesive layer is put to practical use. As the separator, an appropriate film such as the transparent protective film, if necessary, by a method of providing one or more release coats with a release agent such as silicone-based, long-chain alkyl-based, fluorine-based, molybdenum sulfide, etc. Can be formed. For example, the pressure-sensitive adhesive layer may be a single layer or a laminate. As the laminate, for example, a laminate in which different compositions and different types of single layers are combined can be used. Moreover, when arrange | positioning on both surfaces of a polarizing plate, the same adhesive layer may respectively be sufficient, for example, a different composition and a different kind of adhesive layer may be sufficient. The thickness of the pressure-sensitive adhesive layer can be appropriately determined according to, for example, the configuration of the polarizing plate, and is generally 1 to 500 μm.

  In the hard coat film and the polarizing plate with a hard coat film of the present invention, the constituent members (for example, a polarizer, a transparent protective film, etc.) are, for example, salicylic acid ester compounds, benzophenone compounds, benzotriazole compounds, It may have a UV absorbing ability by appropriately treating with a UV absorber such as a cyanoacrylate compound or a nickel complex salt compound.

  The image display device of the present invention includes the hard coat film of the present invention or the polarizing plate with a hard coat film of the present invention. And what is necessary is just to include the said hard coat film or the polarizing plate with a hard coat film, and the other structure and structure are not restrict | limited at all, For example, it replaces with the conventional hard coat film and a polarizing plate. The display format of the image display device is not particularly limited, and examples thereof include various image display devices such as a liquid crystal display device and an organic EL display device.

  In addition to the image display device as described above, the hard coat film and the polarizing plate with a hard coat film of the present invention can be used for optical members such as lenses, mirrors and goggles, for example.

Examples of the present invention will be described below. In the following examples, “parts” and “%” represent “parts by weight” and “% by weight”, respectively.
(Refractive index)
The refractive index was measured with an Abbe refractometer (manufactured by Atago Co., Ltd.).
(Universal hardness)
Measurement was carried out under the following conditions using a Fischer Instruments H100C product name manufactured by Fischer Instruments.
Measurement conditions: Maximum indentation depth 1 μm, maximum load 15 mN (load time 15 seconds)
Indenter shape: Vickers sample: 6 μm thick coating on PET (thickness 100 μm) (measuring substrate: slide glass)
Measurement data: Universal hardness (Maximum depth: Shape correction indentation hardness at about 1 μm)

(Formation of the first hard coat layer)
On an TAC film having a thickness of 80 μm (transparent substrate film: refractive index 1.48, the same shall apply hereinafter), an epoxy acrylate UV curable resin (refractive index 1.48, universal hardness 260 N / mm ² , trade name: Beam Set 374A Arakawa Chemical Industries, Ltd.) was applied with a bar coder. The formed coating film was dried by heating at 100 ° C. for 1 minute, and then irradiated with ultraviolet rays using a metal halide lamp to carry out a curing treatment (integrated light amount: 300 mJ / cm ² ). As a result, a first hard coat layer having a thickness of 15 μm was formed on the TAC film.

(Formation of second hard coat layer)
On the first hard coat layer, a urethane acrylate UV curable resin (refractive index 1.48, universal hardness 300 N / mm ² , trade name: GRANDIC PC-3-Y103, manufactured by Dainippon Ink & Chemicals, Inc.) It was applied with a coder. The formed coating film was dried by heating at 100 ° C. for 1 minute, and then irradiated with ultraviolet rays using a metal halide lamp to carry out a curing treatment (integrated light amount: 300 mJ / cm ² ). Thus, a second hard coat layer (refractive index of 1.50) having a thickness of 5 μm was further formed on the first hard coat layer.

(Formation of a low refractive index layer)
Disperse 70 parts of tetraalkoxysilane and 30 parts of a silane coupling agent having a fluoroalkyl structure and a polysiloxane structure in a mixed solution of isopropyl alcohol / butyl acetate / methyl isobutyl ketone (weight ratio: 70/18/12). Thus, a coating solution having a solid content concentration of 2.0% was prepared. This coating solution was applied onto the second hard coat layer with a bar coder, and the formed coating film was dried and cured by heating at 120 ° C. for 3 minutes. As a result, a low refractive index layer (thickness 0.1 μm, refractive index 1.43) was formed on the second hard coat layer. In this way, an antireflection hard coat was prepared in which the first hard coat layer, the second hard coat layer and the low refractive index layer were laminated in this order on the plastic substrate.

  An antireflection hard coat film was produced in the same manner as in Example 1 except that the thickness of the first hard coat layer after the curing treatment was 10 μm and the thickness of the second hard coat layer after the curing treatment was 10 μm.

  An antireflection hard coat film was produced in the same manner as in Example 1 except that the thickness of the first hard coat layer after the curing treatment was 5 μm and the thickness of the second hard coat layer after the curing treatment was 15 μm.

(Comparative Example 1)
A first hard coat layer (epoxy acrylate-based UV curable resin) is formed on the TAC film in the same manner as in Example 1 except that the thickness after the curing treatment is 20 μm, and a second hard coat layer is further formed. Without formation, a low refractive layer was formed on the first hard coat layer in the same manner as in Example 1. In this way, an antireflection hard coat film was produced.

(Comparative Example 2)
The second hard coat layer was formed in the same manner as in Example 1 except that the second hard coat layer (urethane acrylate UV curable resin, thickness 20 μm) was formed on the TAC film without forming the first hard coat layer. A low refractive index layer was formed thereon to produce an antireflection hard coat film.

(Comparative Example 3)
(Formation of the first hard coat layer)
On the TAC film, the urethane acrylate second hard coat layer (thickness 15 μm after curing) in Example 1 was formed in the same manner as in Example 1, and this was used as the first hard coat layer in Comparative Example 3. .

(Formation of second hard coat layer)
On the first hard coat layer, an epoxy acrylate first hard coat layer (thickness after curing treatment of 5 μm) in Example 1 was formed in the same manner as in Example 1, and this was formed as a second hard coat in Comparative Example 3. A coat layer was formed.

(Formation of a low refractive index layer)
Then, an antireflection hard coat film was prepared by forming a low refractive index layer on the second hard coat layer in the same manner as in Example 1.

(Comparative Example 4)
An antireflection hard coat film was produced in the same manner as in Comparative Example 3 except that the thickness of the first hard coat layer after the curing treatment was 10 μm and the thickness of the second hard coat layer after the curing treatment was 10 μm.

(Comparative Example 5)
An antireflection hard coat film was produced in the same manner as in Comparative Example 3, except that the thickness of the first hard coat layer after the curing treatment was 5 μm and the thickness of the second hard coat layer after the curing treatment was 15 μm.

(Comparative Example 6)
A hard coat film was formed in the same manner as in Example 1 except that the first hard coat film was formed as described below.

(Formation of the first hard coat layer)
Silicone UV curable resin (refractive index 1.48, universal hardness 250 N / mm ² , trade name: AY 42-150, manufactured by Toray Dow Corning Silicone Co., Ltd.) is coated on the TAC film with a bar coder. The formed coating film was dried by heat treatment at 100 ° C. for 1 minute, and then cured by applying ultraviolet irradiation (integrated light amount 300 mJ / cm ² ) using a metal halide lamp. As a result, a first hard coat layer having a thickness of 15 μm was formed on the TAC film.

(Comparative Example 7)
A hard coat film was produced in the same manner as in Example 1 except that the second hard coat layer was formed as described below.

(Formation of second hard coat layer)
On the first hard coat layer, a silicone-based ultraviolet curable resin (refractive index: 1.48, trade name: AY 42-150, manufactured by Toray Dow Corning Silicone Co., Ltd.) is applied with a bar coder to form. The coated film was dried by heat treatment at 100 ° C. for 1 minute, and then a metal halide lamp was irradiated with ultraviolet rays (integrated light amount 300 mJ / cm ² ) to be cured. As a result, a second hard coat layer having a thickness of 5 μm was formed.

The following physical properties were measured for the hard coat films (antireflection hard coat films) of Examples 1 to 3 and Comparative Examples 1 to 7. These results are shown in Table 1 below. In Table 1 below, “HC layer” means “hard coat layer”.
Pencil hardness : Using pencils having different hardnesses, the presence or absence of scratches was determined based on the test method shown in JIS K5400 under a load of 1 kg.
Scratch resistance : (1) The hard coat film was cut into a size of 25 mm in width and 100 mm or more in length, and this was attached to a glass plate as a sample. (2) Steel wool # 0000 was uniformly attached to a smooth cross section of a cylinder having a diameter of 25 mm, and pressed against the surface of the sample under a load of 400 g. The speed of the cylinder to which the steel wool was attached was about 100 mm per second and was reciprocated 10 times. And after making it reciprocate, it confirmed visually that the surface of the said sample did not have a damage | wound of 10 micrometers or more in width, and judged according to the following references | standards.
A: There are no scratches.
B: Although there are fine scratches, the effect on visibility is small.
C: There are obvious scratches and the visibility is impaired.
Adhesion : The test was conducted according to a cross-cut peel test described in JIS K-5400, and the result was expressed as “number of peels / 100”.
Curl : The hard coat film was cut into 10 cm square, and the curvature radius was calculated by measuring warpage and dimensions. If no curl was observed, it was determined as ND.
Crack : The hard coat film was wound around rolls of metals having different diameters, and the presence or absence of cracks at that time was confirmed by visual observation, and the diameter where cracks did not occur was examined.
Reflectivity : A black acrylic plate (thickness: 1.0 mm, manufactured by Nitto Resin Engineering Co., Ltd.) is pasted to the surface of the hard coat film opposite to the laminated surface of the hard coat layer and the low refractive index layer of the TAC film using an adhesive. Combined. This eliminated reflection on the back surface of the hard coat layer. Then, the spectral reflectance (specular reflectance + diffuse reflectance) was measured with a high-sensitivity integrating sphere spectrophotometer, and the total reflectance (Y value) of the C light source / 2 ° field of view was obtained by calculation. In other words, the measurement object is irradiated with light with an inclination of 2 ° from the direction perpendicular to the measurement object, and the light reflected at a position of 2 ° from the direction perpendicular to the measurement object opposite to the light source is measured. The reflectance was obtained.

  As shown in Table 1, the hard coat films (Examples 1 to 3) using epoxy acrylate for the first hard coat layer and urethane acrylate for the second hard coat layer are practically acceptable for curling, cracking and adhesion. It became possible range. Further, the pencil hardness was 4H or more, and the scratch resistance was excellent. On the other hand, the hard coat film containing only one epoxy acrylate layer as the hard coat layer (Comparative Example 1) was excellent in curling resistance, crack resistance and adhesion, but had a pencil hardness of less than 4H and scratch resistance. It was inferior. Further, the hard coat film (Comparative Example 2) containing only one urethane acrylate layer as the hard coat layer has a pencil hardness of 4H or more and excellent scratch resistance, but the curl is remarkably generated and the adhesion is improved. Was also inferior. The hard coat film (Comparative Examples 3 to 5) using urethane acrylate for the first hard coat layer and epoxy acrylate for the second hard coat layer was excellent in curling resistance and crack resistance, but it had pencil hardness and scratch resistance. In the hard coat film (Comparative Example 6) using silicone for the first hard coat layer and urethane acrylate for the second hard coat layer, the pencil hardness was 4H or more and the scratch resistance was excellent. However, the occurrence of curling was remarkable and the adhesion was inferior. The hard coat film (Comparative Example 7) using epoxy acrylate for the first hard coat layer and silicone for the second hard coat layer was inferior in pencil hardness, scratch resistance, and adhesion. Thus, it can be seen that extremely excellent characteristics can be realized with the hard coat film of the present invention.

  As described above, the hard coat fill of the present invention can be said to be extremely useful in the fields of various image display devices, optical members such as lenses and mirrors, and glass products.

FIG. 1 is a cross-sectional view showing an example of the hard coat film of the present invention. FIG. 2 is a cross-sectional view showing another example of the hard coat film of the present invention. FIG. 3 is a cross-sectional view showing an example of the polarizing plate with a hard coat film of the present invention. FIG. 4 is a cross-sectional view showing another example of the polarizing plate with a hard coat film of the present invention.

Explanation of symbols

1: Plastic substrate 2: First hard coat layer 3: Second hard coat layer 4: Low refractive index layer 5: Polarizer 6: Transparent protective film 7, 8: Polarizing plate 10: Hard coat film 20: Hard coat film 30, 40: Polarizing plate with hard coat film

Claims (16)

Including a plastic substrate, a first hard coat layer and a second hard coat layer;
On the plastic substrate, the second hard coat layer is laminated via the first hard coat layer,
The first hard coat layer includes a curable epoxy acrylate,
The hard coat film, wherein the second hard coat layer contains a curable urethane acrylate.   The hard coat film according to claim 1, wherein a universal hardness of the second hard coat layer is larger than a universal hardness of the first hard coat layer.   3. The hard coat film according to claim 1, wherein the first hard coat layer has a thickness of 3 μm to 20 μm.   The hard coat film according to claim 1, wherein the second hard coat layer has a thickness of 3 μm to 20 μm. Hard coat film according to the universal hardness of the first hard coat layer, any one of claims 1 to 4, which is ^{200N / mm 2 ~300N / mm 2} . Hard coat film according to the universal hardness of the second hard coat layer, any one of claims 1 to 5 which is ^{250N / mm 2 ~350N / mm 2} .   The hard coat film according to any one of claims 1 to 6, wherein the curable epoxy acrylate is a photocurable epoxy acrylate.   The hard coat film according to any one of claims 1 to 7, wherein the curable urethane acrylate is a photocurable urethane acrylate.   Furthermore, the hard coat film as described in any one of Claims 1-8 containing an antireflection layer.   The hard coat film according to claim 9, wherein the antireflection layer includes a low refractive index layer having a refractive index lower than that of the second hard coat layer.   The hard coat film according to claim 10, wherein the material for forming the low refractive index layer is a sol-gel material containing a metal alkoxide and a silane coupling agent having a fluoroalkyl group.   The hard coat film according to any one of claims 9 to 11, wherein the antireflection layer is laminated on the second hard coat layer.   The hard coat film according to any one of claims 9 to 12, which is an antireflection film.   A polarizing plate with a hard coat film, comprising a hard coat film and a polarizing plate, wherein the hard coat film is the hard coat film according to claim 1.   The polarizing plate with a hard coat film of Claim 14 currently laminated | stacked on the side in which the hard-coat layer of the plastic base material in the said hard-coat film is not formed.   An image display device comprising at least one of the hard coat film according to any one of claims 1 to 13 and the polarizing plate with a hard coat film according to claim 14 or 15.

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