JP2008058348A - Polarizer protection film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polarizer protection film that eliminates drawbacks of conventional techniques, specifically, the film having excellent surface hardness and optical isotropic property without forming a hard coat layer, and to provide a polarizer protection film that suppresses generation of an iridescent pattern, has excellent visibility and transparency, excellent antireflection characteristics and friction resistance and wear resistance without providing a hard coat layer. <P>SOLUTION: The film is a transparent film made of a vinyl ester resin, having pencil hardness of H or higher, retardation of 5 nm or less, the transmittance of 90% or more for the entire rays, the bottom reflectance of 1% in visible region, and has an antireflection layer comprising layers of high refractive index layers and low refractive index layers on at least one surface of the transparent film. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a polarizer protective film used in a liquid crystal display. More specifically, the present invention relates to a polarizer protective film excellent in surface hardness and optically isotropic without providing a hard coat layer, and further interference. The present invention relates to a polarizer protective film provided with an antireflection layer having no stripes and excellent in scratch resistance and prevention of reflection of external light.

  A polarizer protective film used for a liquid crystal display is required to have high optical isotropy, and in general, a film made of a cellulose-based resin, particularly a triacetyl cellulose resin (TAC film) has been widely used. It was. Since this TAC film has insufficient surface hardness, it is used as a polarizer protective film by laminating a hard coat layer depending on the place of application. That is, in liquid crystal display applications, one polarizer protective film is used for each of the upper surface (image display side) and the lower surface (backlight side) of the polarizer. From the point of view, the hard coat layer as described above is laminated. Furthermore, in order to prevent the reflection of images, organic or inorganic particles are added to the hard coat layer to make the surface an anti-glare surface, reducing the reflection of external light and interference fringes due to the light scattering effect. (Patent Document 1). However, although this method is effective in reducing interference fringes and reflections, there is a problem in that image sharpness is reduced due to excessive light scattering and a screen glare occurs due to the lens effect due to the surface uneven structure. It was not enough in terms of high image quality corresponding to the digital high-definition.

  Conventionally, polyethylene terephthalate (PET), triacetylcellulose (TAC), and the like are used as the base film of the deflector protective film used on the upper side in terms of transparency, haze value, and mechanical properties. However, in a polyester film such as polyethylene terephthalate, a hard coat layer is laminated to compensate for the surface hardness, but it reflects at the interface due to the difference in refractive index between the base film and the hard coat layer provided thereon. Interference fringes due to light interference occur, glare or partial iris reflection occurs when viewed from a certain angle, or poor visibility when used for display applications. Also, TAC film has been the mainstream of deflector protection film because of its excellent transparency, high glass transition point, and excellent hygroscopicity, but on the other hand, retardation in the plane and thickness direction cannot be completely suppressed. Therefore, improvement in image quality has become necessary. Further, as described above, since the surface pencil hardness of the film is about 2B and is very easily damaged, it is necessary to provide a hard coat layer complementarily.

  As a method of improving this phenomenon, a method of providing a primer layer having an intermediate refractive index layer between the base material and the hard coat layer has been proposed. (Patent Document 2) No interference fringes It was not enough. In addition, since the intermediate layer is provided, there are problems such as high costs due to an increase in processes and adhesion of dust.

  As another improvement method, a method of applying a hard coat layer using a solvent that dissolves a base film and dissolving or swelling the base material to reduce interference fringes has been proposed. However, this method is limited to a special solvent and the working environment is extremely bad. Furthermore, there is a problem that haze increases and visibility decreases.

On the other hand, it has been proposed to eliminate interference fringes by using a substrate of triacetyl cellulose (TAC) film and eliminating almost the difference in refractive index from the hard coat layer. (Patent Document 4)
However, the TAC film has a problem that the mechanical strength is weak and it is difficult to reduce the thickness of the film, and because methylene chloride is used as a solvent in the production process, an alternative to the TAC film has been required for environmental conservation. .

As described above, there is a demand for a deflector protective film that improves the drawbacks of the conventional TAC film while requiring high image quality.
JP-A-12-329905 JP 2000-111706 A JP 2003-205563 A JP 2005-96095 A

  The present invention provides the above-mentioned drawbacks in the prior art, specifically, a polarizer protective film excellent in surface hardness and optical isotropy without providing a hard coat layer, and the generation of interference fringes is suppressed. An object of the present invention is to provide a polarizer protective film having excellent visibility and transparency, and further having an excellent antireflection function.

In order to achieve this object, the present inventors have conducted intensive research and found that the object can be achieved by the following means.
That is, the present invention
(1) A polarizer protective film having a vinyl ester composition as a main constituent and a pencil hardness of H or higher,
(2) The polarizer protective film according to (1), wherein the retardation of the transparent film is 5 nm or less.
(3) A vinyl ester composition (a) obtained by reacting a bisphenol-type or alicyclic epoxy compound with (meth) acrylic acid, a polyfunctional acrylate (b), and a vinyl compound or allyl compound. The polarizer protective film according to (1) or (2), comprising one or a plurality of monomers (c) selected from the group, and a liquid curable composition containing a polymerization initiator as necessary,
(4) A polarizer protective film in which a high refractive index layer is laminated on at least one surface of the transparent film according to any one of (1) to (3), and an antireflection layer in which a low refractive index layer is further laminated is provided. ,
(5) A polarizer protective film provided with the antireflection layer according to (4), wherein the total light transmittance is 90% or more and the bottom reflectance in the visible region is 1% or less,
(6) A polarizer provided with the antireflection layer according to (4) or (5), wherein the high refractive index layer is an ionizing radiation curable resin composition and the low refractive index layer is a thermosetting resin composition. Protective film,
(7) A polyfunctional (meth) acrylic compound in which the high refractive index layer using the ionizing radiation curable resin composition contains at least two (meth) acryloyl groups in the molecule, conductive particles and a polymerization initiator, The polarizer protective film according to any one of (4) to (6), which is a layer formed using a liquid ionizing radiation-curable resin composition containing
(8) The refractive index of the low refractive index layer is 1.42 or less, and the refractive index difference between the low refractive index layer and the high refractive index layer is 0.15 or more. Polarizer protective film,
(9) One or more kinds of inorganic oxide and polyfunctional acrylic resin in which the high refractive index layer using the ionizing radiation curable resin composition is selected from tin-containing indium oxide (ITO) and antimony-containing tin oxide (ATO) The polarizer protective film according to any one of (4) to (8), wherein the refractive index is 1.5 to 2.5,
(10) A polarizer protective film provided with the antireflection layer according to any one of (4) to (9), wherein the low refractive index layer is a layer containing porous silica or hollow silica,
It is.

  The polarizer protective film of the present invention has excellent surface hardness and optical isotropy, and further, by providing an antireflection layer, interference fringes are reduced, visibility and transparency are good, and external light is reflected. It is excellent in prevention and has the effect of satisfying both low reflectance and scratch resistance.

  Hereinafter, embodiments of the present invention will be specifically described. The deflector protective film of the present invention is a transparent film comprising a vinyl ester composition as a main component, and has a pencil hardness of H or more, and further, a high refractive index layer on at least one surface of the transparent film, and on the layer And a structure in which a low refractive index layer is laminated.

  The transparent film in the present invention has a vinyl ester composition as a main constituent, and is a kind selected from the group consisting of a vinyl ester composition (a), a polyfunctional acrylate (b), a vinyl compound, and an allyl compound. It is preferable that it is a thing obtained by hardening | curing the liquid curable composition containing several types of monomers (c) and a polymerization initiator as needed. When the vinyl ester composition is the main constituent, the component is at least 50% by weight, preferably 60% by weight or more, and more preferably 70% by weight or more in the liquid curable composition.

  Here, the vinyl ester composition (a) is defined as a vinyl ester that is a series of oligoacrylates that share a secondary hydroxyl group generated by a ring-opening reaction of an epoxy group and a (meth) acryloyl group in the same molecule. The vinyl ester composition (a) preferably used in the present invention is obtained by esterifying a bisphenol type or alicyclic epoxy compound with acrylic acid or methacrylic acid. Examples of the bisphenol type or alicyclic epoxy compound include the following.

  Reaction product of bisphenol A and epichlorohydrin, reaction product of bisphenol F and epichlorohydrin, reaction product of hydrogenated bisphenol A and epichlorohydrin, reaction product of cyclohexanedimethanol and epichlorohydrin, reaction product of norbornane dialcohol and epichlorohydrin, tetra Reaction product of bromobisphenol A and epichlorohydrin, reaction product of tricyclodecanedimethanol and epichlorohydrin, alicyclic diepoxy adipate, alicyclic diepoxy carbonate, alicyclic diepoxy acetal, alicyclic diepoxy carboxylate .

  Moreover, said (c) component is a vinyl compound and / or an allyl compound, for example, an allyl ester monomer, an acrylate ester monomer, a methacrylic acid ester monomer, styrene, α-methylstyrene, acrylonitrile, vinyl acetate, etc. 1 or more types can be used. Moreover, those oligomers can also be used.

  Specific examples of these will be shown below.

Allyl ester monomers: diallyl orthophthalate, diallyl isophthalate, diallyl terephthalate, diallyl 1,4-cyclohexanedicarboxylate, diallyl succinate.
Acrylic acid ester monomer and methacrylic acid ester monomer: morpholine acrylate, methyl methacrylate, isobutyl methacrylate, isodecyl methacrylate, tridecyl methacrylate, lauryl methacrylate, isoamyl methacrylate, ethoxydiethylene glycol acrylate, methoxytriethylene glycol acrylate, phenoxyethyl acrylate, phenoxy polyethylene glycol Acrylate, phenoxy polyethylene glycol acrylate isononyl acrylate, isostearyl acrylate, 2-ethylhexyl methacrylate, 2-hydroxylethyl methacrylate, 2-hydroxypropyl methacrylate, EO adduct dimethacrylate of bisphenol A, bisphenol A O adduct diacrylate, polyethylene glycol dimethacrylate, polyethylene glycol diacrylate, 1,6-hexanediol diacrylate, phenoxyethyl methacrylate, isobornyl methacrylate, benzyl methacrylate, cyclohexyl methacrylate, dicyclopentenyloxyethyl acrylate, dicyclopentenyl Oxyethyl methacrylate, tricyclodecanyl acrylate, tricyclodecanyl methacrylate, acrylamide, N-vinylpyrrolidone, trimethylolpropane diacrylate, trimethylolpropane dimethacrylate, trimethylolpropane tris-oxyethylene acrylate, trimethylolpropane tris-oxy Ethylene methacrylate,
Glycerin diacrylate, glycerin dimethacrylate, glycerin dimethacrylate, 2,6-dibromo-4-tert-butylphenyl acrylate, various urethane acrylates, epoxy acrylates, and the like.

  The pencil hardness of the transparent film of the present invention is H or higher, preferably 2H or higher. To achieve this, it is preferable to use the polyfunctional acrylate (b) in the component, and typical ones are exemplified below. . Polyfunctional acrylate having 3 (more preferably 4 or 5) or more (meth) acryloyloxy groups in one molecule and a modified polymer thereof, for example, pentaerythritol tri (meth) acrylate, pentaerythritol Tetra (meth) acrylate, dipentaerythritol tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, trimethylolpropane tri (meth) acrylate Pentaerythritol triacrylate hexanemethylene diisocyanate urethane polymer and the like can be used. These monomers can be used alone or in combination of two or more. Commercially available polyfunctional acrylic compositions include Mitsubishi Rayon Co., Ltd. (trade name “Diabeam” series, etc.), Nagase Sangyo Co., Ltd. (trade name “Denacol” series, etc.), Shin-Nakamura Co., Ltd .; (Product name “NK Ester” series, etc.), Dainippon Ink and Chemicals Co., Ltd .; (Product name “UNIDIC”, etc.), Toa Gosei Chemical Industry Co., Ltd. Such as “Blenmer” series), Nippon Kayaku Co., Ltd .; (trade name “KAYARAD” series, etc.), Kyoeisha Chemical Co., Ltd .; (trade name “light ester” series, etc.), etc. be able to.

  These polyfunctional acrylates are effective in improving the pencil hardness, but if the blending amount increases, even if the elongation of the film decreases, brittleness may appear and a problem may occur in self-supporting. In the liquid curable composition, 5 to 50% by weight, preferably 10 to 25% by weight is preferable from the viewpoint of balance between hardness and elongation.

  The transparent film used in the present invention is obtained by curing a liquid curable composition in which a polymerization initiator is added to the composition containing the above (a), (b), and (c) as necessary. As a method for curing, either heat curing or ionizing radiation curing, for example, curing by ultraviolet rays or electron beams, or a combination of both methods can be used. In the case of heat curing, it is effective to use an organic peroxide as a polymerization initiator. As the organic peroxide, known ones such as dialkyl peroxides, acyl peroxides, hydroperoxides, ketone peroxides, and peroxyesters can be used. sell. Benzoyl peroxide, t-butylperoxy-2-ethylhexanate, 2,5-dimethyl-2,5-di (2-ethylhexanoyl) peroxyhexane, t-butylperoxybenzoate, t-butylhydroper Oxide, cumene hydroperoxide, dicumyl peroxide, di-t-butyl peroxide, 1,1,3,3-trimethylbutylperoxy-2-ethylhexanate, 2,5-dimethyl-2,5-dibutyl Peroxyhexane. In the case of ultraviolet curing, known photopolymerization initiators as exemplified below can be used as polymerization initiators, and specific examples thereof are as follows. 2,2-dimethoxy-1,2-digenylethan-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, bezophenone, 2-methyl-1- (4-methylthiophenyl) -2-monforinopropanone-1 , 2-Benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1,2-hydroxy-2-methyl-1-phenyl-propan-1-one, 2,4,6-trimethylbenzoyl Diphenyl-phosphine oxide. Moreover, a hardening accelerator can also be added as needed. In the case of electron beam curing, an initiator may not be used.

  The addition amount of the polymerization initiator is 0.05 to 3 parts by weight, preferably 0.1 to 2 parts by weight with respect to 100 parts by weight of the above (a) + (b) + (c).

  In the present invention, a method of forming a film by curing with ionizing radiation is preferable. The liquid curable composition is cast on a rotating drum or an endless driving belt, cured by irradiation with ultraviolet rays or electron beams, and the resulting film is continuously peeled from the drum or the belt. A winding method is preferred. When this method is used, it is preferable to use surfaces of the drum and belt that have been surface-treated with silicone, a fluorine compound or the like in order to facilitate the peeling of the cured film. Further, when the curing reaction is carried out by ionizing radiation, particularly ultraviolet irradiation, it is particularly preferable to carry out in a nitrogen atmosphere. The above-mentioned liquid curable composition may be diluted with a solvent, but it is preferable to use no solvent since a drying step is unnecessary.

  The thickness of the transparent film used in the present invention is preferably 10 to 100 μm, more preferably 20 to 75 μm, from the viewpoint of mechanical strength and handling properties. The transparent film of the present invention may contain various additives, resin compositions, cross-linking agents and the like within a range that does not impair the effects of the present invention. For example, antioxidants, heat stabilizers, ultraviolet absorbers, organic and inorganic particles (for example, silica, colloidal silica, alumina, alumina sol, kaolin, talc, mica, calcium carbonate, barium sulfate, carbon black, zeolite, titanium oxide, Metal fine powders), pigments, dyes, antistatic agents, nucleating agents, acrylic resins, polyester resins, urethane resins, polyolefin resins, polycarbonate resins, alkyd resins, epoxy resins, urea resins, phenol resins, silicone resins, rubber resins , Wax composition, melamine crosslinking agent, oxazoline crosslinking agent, methylolated, alkylolized urea crosslinking agent, acrylamide, polyamide, epoxy resin, isocyanate compound, aziridine compound, various silane coupling agents, various titanates And the like can be mentioned system coupling agent.

The transparent film of the present invention preferably has a retardation of 5 nm or less, that is, 0 to 5 nm, and more preferably 2 nm or less because it is excellent in optical isotropy and image sharpness is improved. In the present invention, the retardation refers to a retardation in the film plane, the main refractive index in the film plane n _x, and n _y, and the thickness of the film and d (nm), Re = | N _x −n _y | × d. Re can be measured using a commercially available automatic birefringence meter (“KOBRA-21ADH” manufactured by Oji Scientific Instruments). In order to obtain such a film, the liquid curable composition is cast on a rotating drum or an endless driving belt and irradiated with ultraviolet rays or an electron beam to be cured. Alternatively, it is important not to apply excessive stress in the film forming method in which the belt is continuously peeled off and wound up. If excessive stress acts on the film during peeling, etc., molecular orientation occurs in the film surface and retardation increases. Therefore, it is effective to apply a treatment capable of peeling with low stress to the surface of the drum or belt. The surface treatment is preferably a treatment with silicone or a fluorine compound.

  The antireflection layer used in the present invention is formed by laminating a high refractive index layer and a low refractive index layer in this order.

  The high refractive index layer in the present invention is a layer having a refractive index of 1.5 or more and 2.5 or less measured by an Abbe refractometer (manufactured by Atago Co., Ltd.) based on JIS K 7105 (1981). Liquid ionizing radiation curing containing an ionizing radiation curable resin composition and further containing a polyfunctional (meth) acrylic compound containing at least two (meth) acryloyl groups in the molecule, conductive particles and a polymerization initiator It is preferable to use a mold resin composition.

  The ionizing radiation curable resin constituting the high refractive index layer may be a transparent resin that is cured by irradiation with an electron beam or ultraviolet rays, and particularly a polyfunctional having two or more (meth) acryloyl groups in the molecule. The (meth) acrylate compound is particularly preferable in the present invention because the solvent resistance and the like are improved. For example, pentaerythritol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, glycerol tri (meth) acrylate, ethylene-modified trimethylolpropane tri (meth) acrylate, tris- (2-hydroxyethyl) -isocyanuric acid ester Trifunctional (meth) acrylates such as tri (meth) acrylate, tetrafunctional (meth) acrylates such as pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, etc. Is mentioned.

  The ionizing radiation curable resin component constituting the high refractive index layer is a (meth) acrylate compound having an acidic functional group such as a carboxyl group, a phosphoric acid group or a sulfonic acid group in order to improve the dispersibility of the particles. preferable. Specifically, examples of the acidic functional group-containing monomer include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, 2-methacryloyloxyethyl succinic acid, 2-methacryloyloxyethyl phthalic acid, and mono (2- (meta ) (Acryloyloxyethyl) acid phosphate, diphenyl-2- (meth) acryloyloxyethyl phosphate, and other phosphoric acid (meth) acrylic acid esters, 2-sulfoester (meth) acrylates, and the like. In addition, addition of resins having urethane bonds, such as (meth) acrylate compounds and urethane (meth) acrylate oligomers having polar bonds such as amide bonds, urethane bonds, ether bonds, etc. as adhesion improving components preferable.

  The conductive particles contained in the high refractive index layer are metal fine particles or metal oxide particles. Among these, metal oxide fine particles are preferable because of high transparency. As the metal oxide fine particles, antimony-containing tin oxide particles (ATO), zinc-containing antimony oxide particles, tin-containing indium oxide particles (ITO), zinc oxide / aluminum oxide particles, antimony oxide particles, and the like are particularly preferable, and tin-containing particles are more preferable. Indium oxide particles (ITO) and antimony-containing tin oxide particles (ATO).

  As the conductive particles, particles having a number average primary particle diameter (sphere equivalent diameter measured by the BET method) of 0.1 μm or less are preferably used, more preferably 0.001 to 0.07 μm, still more preferably. Has a particle diameter of 0.005 to 0.05 μm. When the number average particle diameter exceeds this range, the transparency of the high refractive index layer formed may be lowered, and it may be difficult to obtain a desired haze value.

  The addition amount of the conductive particles needs to be set from the conductivity and the refractive index according to the particles to be used, but in the present invention, it is desired to be 20 to 85% by weight, preferably 35 to 80% by weight.

  The solvent preferably used in the formation of the high refractive index layer of the present invention is formulated to improve coating or printing workability and to improve the dispersibility of the metal compound particles, and dissolves the ionizing radiation curable resin. If it does, conventionally well-known various organic solvents can be used. In particular, in the present invention, an organic solvent having a boiling point of 60 to 180 ° C. is preferable from the viewpoints of viscosity stability and drying property of the resin composition, and among them, the organic solvent having an oxygen atom has an affinity for the conductive particles. Is preferable. Specific examples of the organic solvent include methanol, ethanol, isopropyl alcohol, n-butanol, tert-butanol, ethylene glycol monomethyl ether, 1-methoxy-2-propanol, propylene glycol monomethyl ether, cyclohexane, Preferable examples include butyl acetate, isopropyl acetone, methyl ethyl ketone, methyl isobutyl ketone, diacetyl acetone, and acetyl acetone. These may be used alone or in combination of two or more.

  Further, the amount of the organic solvent may be blended in an arbitrary amount so that the liquid ionizing radiation curable resin composition has a viscosity with good workability according to the coating means and the printing means. The solid content concentration of the radiation curable resin composition is 1 to 20% by weight, preferably about 2 to 10% by weight. The thickness of the high refractive index layer is 70 to 150 nm, preferably 85 to 125 nm, and more preferably 95 to 110 nm, from the viewpoint of the antireflection function.

  The low refractive index layer in the present invention is a layer having a refractive index measured by an Abbe refractometer (manufactured by Atago Co., Ltd.) based on JIS K 7105 (1981) and having a high refractive index. It is a layer whose refractive index difference with the layer is 0.15 or more.

The low refractive index layer preferably contains a silane coupling agent [1] and a fluorine compound [2] having an alkoxy group, and further preferably contains silica particles. The silane coupling agent [1] component is a compound represented by the general formula R (1) _a R (2) _b SiX _{4- (a + b)} or a hydrolysis product thereof. Here, R (2) _b is an alkyl group, alkenyl group, allyl group, and R (1) _a is selected from a halogen group, an epoxy group, an amino group, a mercapto group, a methacryloxy group, or a cyano group. X is a hydrolyzable substituent selected from an alkoxy group having 1 to 4 carbon atoms. a and b are each 0, 1 or 2, and a + b is 1, 2 or 3. The fluorine compound [2] having an alkoxysilyl group is a compound represented by the general formula R (3) _c R (4) _d SiX _{4- (c + d)} or a hydrolysis product thereof. Here, R (3) _c and R (4) _d are each a hydrocarbon group having a fluorine-substituted alkyl group, alkenyl group, allyl group, methacryloxy group, or (meth) acryloyl group. X is a hydrolyzable substituent selected from an alkoxy group having 1 to 4 carbon atoms. c and d are each 0, 1, 2 or 3, and c + d is 1, 2 or 3. In the present invention, the composition for forming the low refractive index layer may contain various additives such as a polymerization inhibitor, an antioxidant, a dispersant, and a leveling agent as necessary.

  In the low refractive index layer of the present invention, silica fine particles [3] are preferably used in combination to increase the hardness. Examples of the silica fine particle [3] component include dry silica, wet silica, colloidally dispersed silica fine particles, and the like, but it is preferable to include spherical silica fine particles having a uniform particle size distribution. The silica fine particles [3] have an average primary particle diameter (sphere equivalent diameter: BET method) of 0.001 to 0.1 μm, preferably 0.005 to 0.07 μm. . In particular, as the silica fine particles [3], the porous or hollow silica fine particles contain air inside, so that the effect of reducing the refractive index can be suitably used. In that case, the porosity of the fine particles is preferably 15% or more and 50% or less from the viewpoint of low refractive index and surface hardness.

  Examples of the hollow particles described above include, for example, JP-A No. 2001-233611, J. MoI. Am. Chem. soc. 2003, P125, 316-317 and the like.

  By including the silica fine particles, the surface hardness is improved, and furthermore, fine irregularities derived from the silica fine particles are formed on the surface of the low refractive index layer. Due to the fine unevenness, it is possible to provide an antireflection effect and a reflection reduction effect without impairing the image clarity.

  In order to form such a low refractive index layer, the addition amount of silica fine particles in the low refractive index forming composition is 20 to 70% by weight, preferably 30 to 50% by weight, and the thickness of the low refractive index layer is 70. It is desirable that the thickness is ˜150 nm, preferably 85 to 125 nm.

  In addition, as a method for forming the low refractive index layer, a silane coupling agent [1], a fluorine compound having an alkoxy group [2], or a mixture of these in advance, and silica fine particles [3] A composition containing methanol, ethanol, isopropyl alcohol, n-butanol, tert-butanol, ethylene glycol monomethyl ether, 1-methoxy-2-propanol, propylene glycol monomethyl ether, cyclohexanone, butyl acetate, isopropyl acetone, methyl ethyl ketone, It is preferable to use a method in which a liquid dispersed in at least one solvent selected from methyl isobutyl ketone, diacetylacetone, and acetylacetone is applied and then dried and cured to form a low refractive index layer.

  As the curing catalyst, a catalyst that promotes the condensation reaction of the silane coupling agent [1] is preferable, and examples thereof include an acid compound. Of these, Lewis acid compounds are preferred. Examples of Lewis acid compounds include metal alkoxides such as acetoacetoxyaluminum and metal chelates. Although the quantity of this curing catalyst can be determined suitably, it is 0.1-1.0 weight part normally with respect to 100 weight part of silane coupling agents [1], for example.

  Next, a polarizer protective film in which an antireflection layer obtained by laminating a high refractive index layer and a low refractive index layer in this order on the transparent film of the present invention will be described.

  The polarizer protective film provided with the antireflection layer of the present invention may have a total light transmittance of 90% or more from the viewpoint of transparency, and when used for a display member, is excellent in image visibility and sharpness. Since it becomes a thing, it is preferable.

  The total light transmittance was measured using a fully automatic direct reading haze computer HGM-2DP (manufactured by Suga Test Instruments Co., Ltd.) to determine the total light transmittance in the film thickness direction, which was the average of 10-point measurements.

  In addition, the polarizer protective film provided with the antireflection layer has a minimum reflectance (bottom reflectance) in the visible light region having a wavelength of 400 to 700 nm of 1% or less, preferably 0.5% or less, more preferably 0. .3% or less. When the bottom reflectance exceeds 1%, the antireflection function is insufficient, and reflection or the like tends to be remarkable.

  The bottom reflectance described in the present invention refers to the lowest reflectance of the surface reflectance at a wavelength of 400 to 700 nm of the antireflection film. A method for measuring the bottom reflectance will be described below. The surface opposite to the measurement surface (antireflection layer side surface) is uniformly roughened with a 320-400 water resistant sandpaper so that the 60 ° gloss (JIS Z 8741) is 10 or less, and then the total light transmittance is obtained. The black paint is applied and colored so as to be 5% or less. Using a spectrophotometer (UV-3150) manufactured by Shimadzu Corporation, the absolute reflection spectrum in the wavelength region of 380 to 800 nm was measured at an incident angle of 5 ° from the measurement surface, and the lowest reflection at a wavelength of 400 to 700 nm. Find the rate.

  In the polarizer protective film provided with the antireflection layer in the present invention, in order to set the bottom reflectance of the surface reflectance at a wavelength of 400 to 700 nm within the above range, the low refractive index layer (d) and the high refractive index layer It is preferable to adjust the refractive index and thickness of (e) as follows. The refractive index (nd) of the low refractive index layer (d) is preferably 1.42 or less, and the refractive index difference between the low refractive index layer (d) and the high refractive index layer (e) is preferably 0.15 or more. . Furthermore, the refractive index of the high refractive index layer (e) is preferably 1.50 to 1.70, more preferably 1.55 to 1.69. The refractive index (nd) of the low refractive index layer (d) is preferably 1.25 to 1.42, and more preferably 1.30 to 1.38.

  Furthermore, it is preferable to adjust the refractive index of the substrate (f). The refractive index (nf) of the substrate is preferably 1.45 to 1.60.

  In order to impart low reflectivity to the polarizer protective film provided with the antireflection layer of the present invention, the thickness of the high refractive index layer (e) is preferably 70 to 150 nm, more preferably 85 to 85 nm. 125 nm, most preferably 95-110 nm. Further, the thickness of the low refractive index layer (d) is preferably 70 to 150 nm, more preferably 85 to 125 nm. When the thicknesses of the high refractive index layer (e) and the low refractive index layer (d) are within this preferred range, the film surface reflectance on the low refractive index layer (d) side becomes low reflective.

[Characteristic measurement method and effect evaluation method]
The characteristic measurement method and effect evaluation method in the present invention are as follows.

1. Evaluation Method of Transparent Film (1) Retardation An automatic birefringence meter (KOBRA-21ADH) manufactured by Oji Scientific Co., Ltd. was used for measurement in a low phase difference mode. The measurement was performed 10 times and the average value was used.

(2) Pencil hardness Measured with a load of 500 g according to JIS K-5400 (1990) using HEIDON (manufactured by Shinto Kagaku Co., Ltd.).

2. Evaluation Method of Antireflection Film (1) Scratch Resistance; Steel Wool Hardness Evaluation Scratch resistance was measured by applying a load of 250 g to # 0000 steel wool on the surface of the low refractive index layer of the antireflection film, a stroke width of 10 cm, and a speed. After 10 reciprocating frictions at 30 mm / sec, the surface was visually observed, and the scratching was evaluated in 5 stages.

    5th grade: No scratches.

    Fourth grade: 1 to 5 scratches.

    3rd grade: 6 to 10 scratches.

    Second grade: 11 or more scratches.

    First grade: Countless scratches on the entire surface.

(2) Reflectance measurement In order to eliminate the influence of back surface reflection, the opposite surface of the measurement surface (antireflection layer side surface) is 320 to 400 so that the 60 ° gloss (JIS Z 8741 (1997)) is 10 or less. After the surface was uniformly roughened with No. water resistant sandpaper, a black paint was applied and colored so that the visible light transmittance was 5% or less. Using a spectrophotometer (UV-3150) manufactured by Shimadzu Corporation, the absolute reflection spectrum in the wavelength region of 380 to 800 nm was measured at an incident angle of 5 ° from the measurement surface, and the lowest reflection at a wavelength of 400 to 700 nm. The rate (bottom reflectance) was determined.

(3) Refractive Index Measurement Based on JIS K 7105 (1981), measurement was performed using an Abbe refractometer (manufactured by Atago Co., Ltd.). The measurement was performed 10 times and the average value was used.

(4) Presence or absence of interference fringes In order to eliminate the influence of back surface reflection, the back surface of the measurement surface (antireflection layer side surface) is roughened with 240 sandpaper in the same way as reflectance measurement, and then black magic ink is used. When the sample prepared by coloring and adjusting was placed in a dark room 30 cm directly under a three-wavelength fluorescent lamp (National Parrook, three-wavelength daylight white (FL 15EX-N 15W)), and the sample was viewed while changing the viewpoint, The evaluation was made based on whether or not the iris pattern was visible.

Iris pattern is not visible: A rank A very weak iris pattern is visible: B rank A weak rainbow color pattern is visible: C rank A strong rainbow color pattern is clearly visible: D rank.

(5) Total light transmittance Using a fully automatic direct reading haze computer HGM-2DP (manufactured by Suga Test Instruments Co., Ltd.), the total light transmittance in the thickness direction of the antireflection film was determined and used as the average value of 10-point measurement.

(6) Anti-reflection effect With regard to the anti-reflection effect of external light, the back surface of the measurement surface (anti-reflection layer side surface) is roughened with a 240th sandpaper as in the reflectance measurement, and then black magic ink is used. The sample prepared by coloring in step 3 is copied in a dark room with a three-wavelength fluorescent lamp (National Parrook, three-wavelength daylight white (FL 15EX-N 15W)) at an angle of 60 ° from the antireflection layer side, and a distance of 1 m. From this, it was judged whether or not the reflected image of the fluorescent light source was clearly confirmed.

The outline of the fluorescent lamp is unclear. ○
The outline of the fluorescent light appears blurred. △
The outline of the fluorescent light is clearly visible. ×

  Next, although this invention is demonstrated based on an Example, this invention is not necessarily limited to these.

(1) Preparation of coating agent (i) Preparation of coating agent B1 A bisphenol A diepoxy compound (374.4 g, 1.20 mol) was added to a 1 L flask equipped with a thermometer, a stirrer, a fractionation condenser, and a gas introduction tube. An acid 206.4 g (2.4 mol), chromium octylate 1.5 g, phosphorous acid 0.15 g, and hydroquinone 0.2 g were added, and the reaction was performed at 120 to 125 ° C. for 2 hours while blowing nitrogen gas. When the acid value reached 11.0, the composition in the flask was poured into a metal vat and cooled to obtain a colorless and transparent vinyl ester composition. This composition is designated as A1. Next, the following components were uniformly dissolved and mixed in the flask to prepare a coating material B1.

A1 resin 70 parts by weight Trimethylolpropane diacrylate 20 parts by weight 1,6-hexanediol diacrylate 10 parts by weight 1-hydroxy-cyclohexyl-phenyl-ketone 1 part by weight (Irgacure 184).

(Iiii) Preparation of coating agent B2 The same components as described above were uniformly dissolved and mixed in the flask except that 5 parts by weight of dipentaerythritol hexaacrylate (DPHA: Nippon Kayaku Co., Ltd.) was added. B2 was produced.

A1 resin 70 parts by weight Trimethylolpropane diacrylate 20 parts by weight 1,6-hexanediol diacrylate 10 parts by weight Dipentaerythritol hexaacrylate 5 parts by weight 1-hydroxy-cyclohexyl-phenyl-ketone 1 part by weight (Irgacure 184).

(Iii) Preparation of coating agent B3 Except that the addition amount of dipentaerythritol hexaacrylate is the following value, in the same manner as coating agent B2, the following components were uniformly dissolved and mixed in the flask to prepare coating agent B3. Produced.

A1 resin 70 parts by weight Trimethylolpropane diacrylate 20 parts by weight 1,6-hexanediol diacrylate 10 parts by weight Dipentaerythritol hexaacrylate 10 parts by weight 1-hydroxy-cyclohexyl-phenyl-ketone 1 part by weight (Irgacure 184).

(Iv) Preparation of coating agent B4 Except that the addition amount of dipentaerythritol hexaacrylate is the following value, in the same manner as coating agent B2, the following components are uniformly dissolved and mixed in the flask to prepare coating agent B4. Produced.

A1 resin 70 parts by weight Trimethylolpropane diacrylate 20 parts by weight 1,6-hexanediol diacrylate 10 parts by weight Dipentaerythritol hexaacrylate 20 parts by weight 1-hydroxy-cyclohexyl-phenyl-ketone 1 part by weight (Irgacure 184).

(2) Production of transparent film (v) Production of transparent film C1 After casting the coating material B1 onto a fluorine-treated drum that is continuously driven, the cumulative radiation intensity is 1000 mJ / cm ² under a nitrogen atmosphere. After the coating material B1 was cured by irradiating the ultraviolet rays, the film was peeled off from the drum to obtain a transparent film C1 having a thickness of 100 μm.

(Vi) Production of transparent film C2 A transparent film C2 having a thickness of 100 μm was obtained in the same manner as C1, except that the coating material was B2.

(Vii) Production of transparent film C3 A transparent film C3 having a thickness of 100 μm was obtained in the same manner as C1, except that the coating material was B3.

(Viii) Production of transparent film C4 A transparent film C4 having a thickness of 100 μm was obtained in the same manner as C1, except that the coating agent was B4.

  Next, an example is given about an antireflection film and the present invention is explained.

[Adjustment of paint]
A. High refractive index paint-1
Refractive coating film refractive index by stirring a mixture of 6 parts by weight of tin-containing indium oxide particles (ITO), 2 parts by weight of dipentaerythritol hexaacrylate, 18 parts by weight of methanol, 54 parts by weight of polypropylene glycol monoethyl ether, and 20 parts by weight of isopropyl alcohol. 1.64 paints were prepared.

B. High refractive index paint-2
A mixture of 6 parts by weight of antimony-containing lead oxide particles (ATO), 2 parts by weight of dipentaerythritol hexaacrylate, 54 parts by weight of methyl ethyl ketone, and 38 parts by weight of isopropyl alcohol was stirred to prepare a paint having a coating film refractive index of 1.61.

C. Preparation of Low Refractive Index Paint-1 219 parts by weight of methyltrimethoxysilane (KBM-7103 manufactured by Shin-Etsu Silicone) was hydrolyzed with 89 parts by weight of 0.5N formic acid while stirring at 20 ° C. ± 5 ° C. After 60 minutes, 412 parts by weight of isopropyl alcohol was mixed to prepare a treatment liquid (X1).

  Similarly, 158 parts by weight of 3,3,3-trifluoropropyltrimethoxysilane (KBM-7103 manufactured by Shin-Etsu Silicone) was hydrolyzed with 41 parts by weight of 1N formic acid while stirring at 30 ° C. ± 10 ° C. After 60 minutes, isopropyl alcohol 521 double parts were mixed to prepare a treatment liquid (X2).

  Next, a silica slurry (X3) composed of 144 parts by weight of hollow silica particles having an outer shell with an average primary particle diameter of 50 nm and a porosity of 30% (through rear manufactured by Catalyst Chemical Industry Co., Ltd.) and 560 parts by weight of isopropyl alcohol was prepared. .

  720 parts by weight of treatment liquid (X1), 720 parts by weight of treatment liquid (X2), 704 parts by weight of silica slurry (X3), 356 parts by weight of methanol, 4272 parts by weight of isopropyl alcohol, and 713 parts by weight of polypropylene glycol monoethyl ether were mixed. Thereafter, 15 parts by weight of acetoacetoxyaluminum as a curing catalyst was added and mixed again with stirring to prepare a paint having a refractive index of 1.36.

D. Adjustment of Low Refractive Index Paint-2 219 parts by weight of methyltrimethoxysilane, 158 parts by weight of 3,3,3-trifluoropropyltrimethoxysilane, hollow silica slurry (X5: Suriria S special product (catalyst) 50%) hollow silica particles produced in the same manner as X3) 704 parts by weight, 713 parts by weight of polypropylene glycol monoethyl ether were mixed with stirring, and 1 part by weight of phosphoric acid and 130 parts by weight of water were blended. Hydrolysis was performed for 60 minutes with stirring at a temperature of ± 10 ° C., and the temperature was raised to 80 ° C. ± 5 ° C. and polymerization was performed with stirring for 60 minutes to obtain silica particle-containing oligomer (X4).

Next, 1200 parts by weight of silica particle-containing oligomer (X4) and 5244 parts by weight of isopropyl alcohol were stirred and mixed, and then 15 parts by weight of acetoxyaluminum was added as an effect catalyst and stirred and mixed again to prepare a paint having a refractive index of 1.35. did.

[Examples 1-3]
Table 1 shows the results of evaluating the properties of the transparent film (C2 to C4) containing the vinyl ester composition obtained by the above method as a main constituent as a polarizer protective film. (C2: Example 1, C3: Example 2, C4: Example 3) The pencil hardness, which is the protective property of the surface, was H or higher and the surface hardness was excellent. The retardations were all optically isotropic and excellent values of 5 nm or less.

[Comparative Example 1]
Table 1 shows the results of evaluation of the transparent film C1 as a polarizer protective film. The pencil hardness, which is a protective property of the surface, was inferior to HB and surface hardness. The retardation was 1.2 nm.

[Comparative Example 2]
Table 1 shows the results of evaluation of a commercially available triacetyl cellulose film (Fuji Photo Film Co., Ltd., Fujitac, thickness 100 μm) as a polarizer protective film.

  The pencil hardness, which is a protective property of the surface, was 2B, which was inferior to the surface hardness. The retardation was 6 nm.

Example 4
On the transparent film C3 of the vinyl ester resin obtained by the above method, a high refractive index paint-1 is applied using a micro gravure coater, dried at 80 ° C., and then irradiated with ultraviolet rays of 500 mJ / cm ^2. The work layer was cured to form a high refractive index layer having a thickness of about 0.1 μm. Next, low refractive index paint-1 on the high refractive index layer
Was coated with a micro gravure coater, dried at 80 ° C., and then heat-treated at 130 ° C. to cure the coating layer, forming a low refractive index layer having a thickness of about 0.1 μm, and providing an antireflection layer A polarizer protective film was prepared. As shown in Table 2, the retardation and pencil hardness of the transparent film are excellent, and the polarizer protective film provided with the obtained antireflection layer has a bottom reflectance of 0.35% and a good value, No interference fringes were observed, and the scratch resistance was as good as grade 4.

[Examples 5 to 7]
A polarizer protective film provided with an antireflection layer was produced in the same manner as in Example 4 except that the type of the high refractive index paint and the type of the low refractive index paint were changed as shown in Table 2. The retardation and pencil hardness of the transparent film were excellent, and the properties of the polarizer protective film provided with the antireflection layer are shown in Table 2, and all showed good properties.

Example 8
A polarizer protective film provided with an antireflection layer was produced in the same manner as in Example 4 except that C2 was used instead of the transparent film C3. The properties of the polarizer protective film provided with the antireflection layer are shown in Table 2, and all showed good properties.

Example 9
A polarizer protective film provided with an antireflection layer was produced in the same manner as in Example 4 except that C4 was used instead of the transparent film C3. The properties of the polarizer protective film provided with the antireflection layer are shown in Table 2, and all showed good properties.

[Comparative Example 3]
A polarizer protective film provided with an antireflection layer in the same manner as in Example 4 except that a commercially available optically-adhesive polyester film for optical use (Lumirror (registered trademark) QT63 manufactured by Toray Industries, Inc., thickness 100 μm) was used as the polarizer protective film. Manufactured. The retardation of the polyester film was 2300 nm, and the pencil hardness was inferior to HB. As shown in Table 2, the properties of the polarizer protective film provided with the antireflection layer were inferior in scratch resistance and inferior in interference fringes. The bottom reflectance of the antireflection film was as good as 0.21%. [Comparative Example 4]
An antireflection film was produced in the same manner as in Example 4 except that a commercially available optical triacetylcellulose film (Fuji Photo Film Co., Ltd., Fujitac, thickness: 100 μm) was used as the polarizer protective film. The retardation of the triacetyl cellulose film was 6 nm, and the pencil hardness was inferior at 2B. As shown in Table 2, the properties of the polarizer protective film provided with the antireflection layer were such that no interference fringes were observed and the bottom reflectance was excellent at 0.53%, but the scratch resistance was poor. .

  The film of the present invention is intended to provide a polarizer protective film excellent in optical isotropy and surface hardness without providing a hard coat layer, and further, the occurrence of an iris pattern is suppressed, An object of the present invention is to provide a polarizer protective film having excellent visibility and transparency, having an excellent antireflection characteristic without providing a hard coat layer, and further having excellent friction resistance and wear resistance. To do. It can be used in display applications such as LCD.

Claims (10)

A polarizer protective film comprising a vinyl ester composition as a main constituent and a pencil hardness of H or higher. The polarizer protective film according to claim 1, wherein the transparent film has a retardation of 5 nm or less. The transparent film is selected from the group consisting of a vinyl ester composition (a), a polyfunctional acrylate (b), a vinyl compound, and an allyl compound obtained by reacting a bisphenol type or alicyclic epoxy compound with (meth) acrylic acid. The polarizer protective film of Claim 1 or 2 formed using the liquid curable composition containing the 1 type or multiple types of monomer (c) and the polymerization initiator as needed. The polarizer protective film which provided the antireflection layer by which the high refractive index layer was laminated | stacked on the at least single side | surface of any one of Claims 1-3, and also the low refractive index layer was laminated | stacked. The polarizer protective film provided with the antireflection layer according to claim 4, wherein the total light transmittance is 90% or more and the bottom reflectance in the visible region is 1% or less. The polarizer protective film provided with the antireflection layer according to claim 4 or 5, wherein the high refractive index layer uses an ionizing radiation curable resin composition and the low refractive index layer uses a thermosetting resin composition. The high refractive index layer using the ionizing radiation curable resin composition contains a polyfunctional (meth) acryl compound containing at least two (meth) acryloyl groups in the molecule, conductive particles, and a polymerization initiator. The polarizer protective film according to claim 4, which is a layer formed using a liquid ionizing radiation curable resin composition. The polarizer protective film according to claim 4, wherein the refractive index of the low refractive index layer is 1.42 or less, and the refractive index difference between the low refractive index layer and the high refractive index layer is 0.15 or more. The high refractive index layer formed using the ionizing radiation curable resin composition is composed of one or more inorganic oxides selected from tin-containing indium oxide (ITO) and antimony-containing tin oxide (ATO) and a polyfunctional acrylic resin. The polarizer protective film according to claim 4, wherein the refractive index is 1.5 to 2.5. The polarizer protective film according to claim 4, wherein the low refractive index layer is a layer containing porous silica or hollow silica.