JP2013076969A - Antireflection film, antireflective polarizing plate and transmissive liquid crystal display - Google Patents

Abstract

[PROBLEMS] To provide a saponification resistance that does not change the antireflection performance even when a saponification treatment is performed by immersing the antireflection film in an alkaline solution without applying a protective film when the antireflection film is made into a polarizing plate. The object is to provide an excellent antireflection film.
In an antireflection film in which a hard coat layer and a low refractive index layer are laminated on one surface of a transparent substrate, the hard coat layer contains a polyfunctional monomer having a (meth) acryloyloxy group as a main component. And the low refractive index layer is formed of a low refractive index coating agent containing at least an ultraviolet curable material and low refractive index particles, and the low refractive index layer is Low refractive index coating agent comprising: an ultraviolet curable material; and low refractive index nano-particles in a range of 0.4 parts by weight or more and less than 0.6 parts by weight with respect to 1 part by weight of the ultraviolet curable material. Manufactured from.
[Selection] Figure 1

Description

  The present invention relates to an antireflection film having antireflection performance and antistatic performance. Furthermore, it is related with the antireflection film applied to the display screen of displays, such as LCD, PDP, CRT, a projection display, and an EL display.

  In general, a display is used in an environment where external light or the like enters regardless of whether the display is used indoors or outdoors. Incident light such as external light is specularly reflected on the display surface and the like, and the reflected image thereby mixes with the display image, thereby degrading the screen display quality. Therefore, it is required to provide an antireflection function on the display surface or the like.

  A polarizing plate, which is an indispensable optical material in a liquid crystal display (LCD), generally has a structure in which a polarizing layer is sandwiched between two antireflection films. As a result, reflection of external light and the like are prevented, and the polarizing plate is excellent in scratch resistance, antifouling properties, and the like. In this case, a polyester film, a triacetyl cellulose film, or the like is generally used as the base film, but when used for a liquid crystal display, a triacetyl cellulose film is often used because of optical superiority. The triacetyl cellulose-based film needs to be saponified in order to improve adhesion with polyvinyl alcohol which is a constituent element of the polarizing plate. In the above configuration, it is common to immerse the entire laminate in a saponification treatment solution after providing a hard coat layer or a low refractive index layer on a triacetyl cellulose film (Patent Document 1).

  The saponification treatment is carried out after forming a hard coat layer or a low refractive index layer on the substrate film. In the saponification treatment, the vicinity of the surface of the antireflection film is hydrolyzed by the alkaline solution. Therefore, when the antireflection film is subjected to a saponification treatment, the saponification is usually performed with a protective film attached to the outermost surface. When saponification is performed without using a protective film, the adhesion with the low refractive index layer formed on the hard coat layer is deteriorated, and the antireflection performance is changed.

International Publication No. WO2009 / 008240

  In the present invention, when the antireflection film is made into a polarizing plate, the antireflection performance does not change even if the antireflection film is immersed in an alkaline solution and the saponification treatment is carried out without wearing the protective film. An object of the present invention is to provide an antireflection film excellent in the above.

  As a means for solving the above problems, the invention according to claim 1 is the antireflection film in which the hard coat layer and the low refractive index layer are laminated on one surface of the transparent substrate, wherein the hard coat layer is Low refractive index formed from a polymer mainly composed of a polyfunctional monomer having a (meth) acryloyloxy group, and the low refractive index layer contains at least an ultraviolet curable material and low refractive index particles And the low refractive index layer is in the range of 0.4 parts by weight or more and less than 0.8 parts by weight with respect to 1 part by weight of the ultraviolet curable material and the ultraviolet curable material. An antireflection film produced from a low refractive index coating agent containing low refractive index nanoparticles.

  The invention according to claim 2 is the antireflection film according to claim 1, wherein the antireflection film is subjected to alkali saponification treatment.

  In the invention according to claim 3, the average luminous reflectance is 0.3% or more and 2.5% or less, the total light transmittance is 95% or more and 98% or less, and the haze is 0.00. It is 01% or more and 0.40% or less, and surface roughness (Ra) satisfy | fills all in the range of 0.3 nm or more and 3.0 nm or less, The Claim 1 or Claim 2 characterized by the above-mentioned. It is an antireflection film.

  In the invention according to claim 4, the low refractive index layer is dried at a drying temperature within the range of −20 ° C. or higher and + 20 ° C. or lower of the boiling point of the main solvent, and the integrated light quantity is 100 mJ / cm 2 or more and 400 mJ / cm 2. The antireflection film according to any one of claims 1 to 3, wherein the antireflection film is produced by ultraviolet irradiation within the following range.

  The invention according to claim 5 is the antireflection film according to any one of claims 1 to 4, wherein the polarizing layer and the second transparent group are formed on the surface of the transparent base material where the low refractive index layer is not formed. An antireflective polarizing plate comprising materials in order.

  The invention according to claim 6 comprises, in order from the observer side, the antireflection polarizing plate according to claim 5, the liquid crystal cell, the second polarizing plate, and the backlight unit in this order, and the antireflection A transmissive liquid crystal display characterized in that a liquid crystal cell is held on the side of the low polarizing layer non-formation surface of the polarizing plate.

  In the antireflection film of the present invention, when the antireflection film is converted into a polarizing plate, the antireflection film is not reflected even if it is saponified by immersing the antireflection film in an alkaline solution without wearing the protective film. It is possible to provide an antireflection film that does not change the prevention performance and has excellent saponification resistance.

It is a section conceptual diagram of the antireflection film of the present invention. It is a cross-sectional conceptual diagram of the polarizing plate of this invention. It is a cross-sectional conceptual diagram of the transmissive liquid crystal display using the polarizing plate of this invention.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. FIG. 1 is a conceptual cross-sectional view of an antireflection film 1 according to the present invention, comprising a hard base layer 12 on a transparent substrate 11 and a low refractive index layer 13 thereon. The hard coat layer 12 is formed by curing an ionizing radiation curable material, and mainly imparts scratch resistance. The low refractive index layer 13 is provided on the outermost layer of the antireflection film 1 and imparts an antireflection function, an antifouling function, and an abrasion resistance function.

  As the transparent substrate 11, films or sheets made of various organic polymers can be used. For example, a base material usually used for an optical member such as a display can be cited, considering optical properties such as transparency and refractive index of light, and further various physical properties such as impact resistance, heat resistance and durability, Polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate and polyethylene naphthalate, celluloses such as triacetyl cellulose, diacetyl cellulose and cellophane, polyamides such as 6-nylon and 6,6-nylon, polymethyl methacrylate, etc. Those made of organic polymers such as acrylic, polystyrene, polyvinyl chloride, polyimide, polyvinyl alcohol, polycarbonate, ethylene vinyl alcohol are used. In particular, polyethylene terephthalate, triacetyl cellulose, polycarbonate, and polymethyl methacrylate are preferable. Furthermore, functions can be added to these organic polymers by adding known additives such as antistatic agents, ultraviolet absorbers, infrared absorbers, plasticizers, lubricants, colorants, antioxidants, flame retardants, etc. Can also be used. The transparent substrate may be composed of one or a mixture of two or more selected from the above organic polymers, or a polymer, or may be a laminate of a plurality of layers.

  Especially, since a triacetylcellulose film has little birefringence and favorable transparency, when using the antireflection film 1 of this invention for a liquid crystal display, it can be used conveniently. The refractive index of the triacetyl cellulose film is about 1.50, which is lower than that of other transparent substrates. For example, a polyethylene terephthalate film widely used as a transparent substrate is about 1.60.

  Moreover, in the antireflection film 1 of the present invention, it is preferable to provide a hard coat layer 12 between the transparent substrate 11 and the low refractive index layer 13. By providing the hard coat layer 12, the antireflection film 1 having excellent scratch resistance can be obtained.

  The hard coat layer in the antireflection film of the present invention is preferably composed of a polymer mainly composed of a functional monomer having a (meth) acryloyloxy group.

  Functional monomers having a (meth) acryloyloxy group include pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipenta Erythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol triacrylate, hexamethylene diisocyanate urethane prepolymer, pentaerythritol triacrylate, toluene diisocyanate urethane prepolymer, pentaerythritol Examples include triacrylate, isophorone diisocyanate urethane prepolymer, etc. It is possible.

  In the antireflection film 1 of the present invention, a coating liquid containing a functional monomer having a (meth) acryloyloxy group is applied onto the transparent substrate 11 and dried as necessary. The hard coat layer 12 is formed by irradiating with ionizing radiation.

  After applying a coating solution for forming a low refractive index layer using a low refractive index coating agent on the hard coat layer 12, it is dried and reflected by forming a low refractive index layer 13 by irradiating with ionizing radiation. The prevention film 1 can be produced.

  The antireflection film 1 of the present invention is provided on a transparent substrate 11 in the order of at least a hard coat layer 12 and a low refractive index layer 13, and the low refractive index layer 13 includes at least an ultraviolet curable material and a low refractive index. Formed from a coating liquid for forming a low refractive index layer comprising a low refractive index coating agent containing fine refractive index nanoparticles, and 0.4 parts by weight or more and less than 0.8 parts by weight with respect to 1 part by weight of the ultraviolet curable material The low refractive index nanoparticle which is in the range is contained.

  The low refractive index coating agent used for the low refractive index layer 13 of the present invention will be described. The low refractive index coating agent of the present invention contains an ultraviolet curable material, low refractive index nanoparticles, and a photopolymerization initiator.

  An acrylic material can be used as the ultraviolet curable material added to the coating solution for forming the low refractive index layer. Acrylic materials are synthesized from polyfunctional or polyfunctional (meth) acrylate compounds such as polyhydric alcohol acrylic acid or methacrylic acid ester, diisocyanate and polyhydric alcohol, acrylic acid or methacrylic acid hydroxy ester, and the like. Such a polyfunctional urethane (meth) acrylate compound can be used.

  Besides these, as ionizing radiation type materials, polyether resins having an acrylate functional group, polyester resins, epoxy resins, alkyd resins, spiroacetal resins, polybutadiene resins, polythiol polyene resins, and the like can be used. .

  Examples of the monofunctional (meth) acrylate compound include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl ( (Meth) acrylate, t-butyl (meth) acrylate, glycidyl (meth) acrylate, acryloylmorpholine, N-vinylpyrrolidone, tetrahydrofurfuryl acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isobornyl (meth) ) Acrylate, isodecyl (meth) acrylate, lauryl (meth) acrylate, tridecyl (meth) acrylate, cetyl (meth) acrylate, stearyl (meth) acrylate, benzyl (Meth) acrylate, 2-ethoxyethyl (meth) acrylate, 3-methoxybutyl (meth) acrylate, ethyl carbitol (meth) acrylate, phosphoric acid (meth) acrylate, ethylene oxide modified phosphoric acid (meth) acrylate, phenoxy (meta) ) Acrylate, ethylene oxide modified phenoxy (meth) acrylate, propylene oxide modified phenoxy (meth) acrylate, nonylphenol (meth) acrylate, ethylene oxide modified nonylphenol (meth) acrylate, propylene oxide modified nonylphenol (meth) acrylate, methoxydiethylene glycol (meth) Acrylate, methoxypolyethylene glycol (meth) acrylate, methoxypropylene glycol (meth) acrylate 2- (meth) acryloyloxyethyl-2-hydroxypropyl phthalate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, 2- (meth) acryloyloxyethyl hydrogen phthalate, 2- (meth) acryloyloxypropyl hydrogen Phthalate, 2- (meth) acryloyloxypropyl hexahydrohydrogen phthalate, 2- (meth) acryloyloxypropyl tetrahydrohydrogen phthalate, dimethylaminoethyl (meth) acrylate, trifluoroethyl (meth) acrylate, tetrafluoropropyl (meth) acrylate , Hexafluoropropyl (meth) acrylate, octafluoropropyl (meth) acrylate, octafluoropropyl (meth) acrylate, 2 -Adamantane derivatives mono (meth) acrylates such as adamantyl acrylate having a monovalent mono (meth) acrylate derived from adamantane and adamantanediol.

  Examples of the bifunctional (meth) acrylate compound include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, butanediol di (meth) acrylate, hexanediol di (meth) acrylate, and nonanediol di (meth). Acrylate, ethoxylated hexanediol di (meth) acrylate, propoxylated hexanediol di (meth) acrylate, diethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, polypropylene glycol di ( (Meth) acrylate, neopentyl glycol di (meth) acrylate, ethoxylated neopentyl glycol di (meth) acrylate, tripropylene glycol Di (meth) acrylate, di (meth) acrylate, such as hydroxypivalic acid neopentyl glycol di (meth) acrylate.

  Examples of the trifunctional or higher functional (meth) acrylate compound include trimethylolpropane tri (meth) acrylate, ethoxylated trimethylolpropane tri (meth) acrylate, propoxylated trimethylolpropane tri (meth) acrylate, and tris 2-hydroxyethyl. 3 such as tri (meth) acrylate such as isocyanurate tri (meth) acrylate and glycerol tri (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol tri (meth) acrylate, ditrimethylolpropane tri (meth) acrylate Functional (meth) acrylate compounds, pentaerythritol tetra (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, dipentaerythritol tetra Trifunctional or more polyfunctional (meth) such as (meth) acrylate, dipentaerythritol penta (meth) acrylate, ditrimethylolpropane penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, ditrimethylolpropane hexa (meth) acrylate Examples thereof include acrylate compounds and polyfunctional (meth) acrylate compounds in which a part of these (meth) acrylates is substituted with an alkyl group or ε-caprolactone.

  The low refractive index nanoparticle contained in the low refractive index coating agent of the present invention includes LiF, MgF, 3NaF.AlF or AlF (all of which have a refractive index of 1.4), or Na3AlF6 (cryolite, refractive index of 1). .33), low refractive index particles made of a low refractive material such as silica can be used. Moreover, the particle | grains which have a space | gap inside a particle | grain can be used suitably. In the case of particles having voids inside the particles, the voids can be made to have a refractive index of air (≈1), so that they can be low refractive index particles having a very low refractive index. Specifically, porous silica particles and low refractive index silica particles having voids inside can be used.

  The average particle size is preferably 1 nm or more and 100 nm or less. When the particle diameter exceeds 100 nm, light is remarkably reflected by Rayleigh scattering, and the low refractive index layer tends to be whitened and the transparency of the antireflection film tends to be lowered. On the other hand, when the particle size is less than 1 nm, problems such as particle aggregation in the low refractive index layer 13 due to particle aggregation occur.

  The average particle diameter means a 50% particle diameter (d50 median diameter) when particles in a solution are measured by a dynamic light scattering method and the particle diameter distribution is expressed by a cumulative distribution.

  Moreover, as a space | gap of the silica particle which has a space | gap inside, it is preferable that they are 20 nm or more and 50 nm or less. This is because, when the gap exceeds 50 nm, sufficient scratch resistance cannot be obtained and the antireflection film provided on the display surface is not suitable. On the other hand, when the gap is less than 20 nm, the refractive index is 1.45 or more, and the average luminous reflectance is 2.5% or more.

  As an example of silica particles having voids inside, while maintaining a spherical shape, the refractive index is 1.30 lower than the refractive index of glass 1.45, the radius is 20 nm to 25 nm, and the density (ρ1 ) Has a spherical structure in the center, and the periphery is covered with layers of different densities (ρ2) having a thickness of 10 nm to 15 nm, and the values of (ρ1 / ρ2) are 0.5, 0.1, 0.0 The center part of the silica particles is a structural model that has a density of about 1/10 of the external silica.

  The ratio of the low refractive index nanoparticles in the low refractive index coating agent of the present invention is such that the content of the low refractive index nanoparticles is 0.4 parts by weight or more and 0.8 parts by weight with respect to 1 part by weight of the ultraviolet curable material. It is within the range of less than parts by weight. When the amount is less than 0.4 parts by weight, the average luminous reflectance is 2.5% or more. When the amount is 0.8 parts by weight or more, film separation occurs when saponification (alkali) treatment is performed. It is because it ends up.

  If necessary, a solvent and various additives can be added to the low refractive index coating agent. Solvents include aromatic hydrocarbons such as toluene, xylene, cyclohexane and cyclohexylbenzene, hydrocarbons such as n-hexane, dibutyl ether, dimethoxymethane, dimethoxyethane, diethoxyethane, propylene oxide, dioxane, dioxolane, and trioxane. , Ethers such as tetrahydrofuran, anisole and phenetole, and ketones such as methyl isobutyl ketone, methyl butyl ketone, acetone, methyl ethyl ketone, diethyl ketone, dipropyl ketone, diisobutyl ketone, cyclopentanone, cyclohexanone, methylcyclohexanone, and methylcyclohexanone , Ethyl formate, propyl formate, n-pentyl formate, methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, Suitable for coating from among esters such as acid n-pentyl and γ-ptyrolactone, cellosolves such as methyl cellosolve, cellosolve, butyl cellosolve, cellosolve acetate, alcohols such as methanol, ethanol, isopropyl alcohol, water, etc. Etc. are selected as appropriate. In addition, a surface adjusting agent, a leveling agent, a refractive index adjusting agent, an adhesion improver, a photosensitizer, and the like can be added as additives to the low refractive index coating agent.

  In the antireflection film 1, an antireflection layer having a single layer structure composed of a single low refractive index layer 13 or an antireflection layer having a laminated structure composed of a repeating structure of a low refractive index layer and a high refractive index layer is provided. It is known to form. In the antireflection film of the present invention, the antireflection layer preferably has a single layer structure of a low refractive index layer containing low refractive index particles in a binder matrix.

  In addition, as a method of forming the antireflection layer, a method by a wet film forming method in which a coating liquid for forming an antireflection layer is applied to the surface of the antiglare layer to form an antireflection layer, a vacuum deposition method, a sputtering method, or a CVD method The vacuum film forming method for forming the antireflection layer in vacuum is classified as follows.

  When forming an antireflection layer with a laminated structure consisting of a repeating structure of a low refractive index layer and a high refractive index layer, it is necessary to precisely control the film thickness of the high refractive index layer and low refractive index layer to be formed. It is necessary to form by a vacuum film forming method. In the antireflection film of the present invention, an antireflection film is produced at low cost by forming an antireflection film by a wet film formation method using a low refractive index coating liquid containing low refractive index particles and a binder matrix. be able to.

  At this time, in the low refractive index layer single layer, the optical film thickness (nd) obtained by multiplying the film thickness (d) by the refractive index (n) of the low refractive index layer is 1/4 of the wavelength of visible light. Are formed to be equal.

  As a coating method for applying a coating solution for forming a low refractive index layer using a low refractive index coating agent on a transparent substrate on which a hard coat layer is formed, a roll coater, a reverse roll coater, a gravure coater, A coating method using a knife coater, bar coater or die coater can be used.

  By irradiating the coating film obtained by applying a coating solution for forming a low refractive index layer using a low refractive index coating agent on a transparent substrate on which a hard coat layer is formed, A refractive index layer is formed. As the ionizing radiation, ultraviolet rays and electron beams can be used. In the case of ultraviolet curing, a light source such as a high pressure mercury lamp, a low pressure mercury lamp, an ultrahigh pressure mercury lamp, a metal halide lamp, a carbon arc, or a xenon arc can be used. In the case of electron beam curing, electron beams emitted from various electron beam accelerators such as cockloftwald type, bandegraph type, resonant transformer type, insulated core transformer type, linear type, dynamitron type, and high frequency type can be used. .

  After the coating liquid for forming a low refractive index layer is applied on the hard coat layer 12, a drying step is provided to remove the solvent in the coating film on the hard coat layer 12. As a method for producing an antireflection film according to an embodiment of the present invention, the drying temperature of the coating film in the drying step is in the range of the boiling point of the main solvent from −20 ° C. to the boiling point of the main solvent + 20 ° C. And

  When the drying temperature is lower than the boiling point −20 ° C. of the main solvent used for the coating liquid for forming the low refractive index layer 13, the solvent is not sufficiently dried and the silicone material component contained in the low refractive index layer 13 is a film. It remains on top, and the antifouling property and scratch resistance of the low refractive index layer 13 are lowered. On the other hand, when the drying temperature exceeds the boiling point of the main solvent used in the coating liquid for forming the low refractive index layer 13 + 20 ° C., the production cost increases, and wrinkles called heat wrinkles are formed in the antireflection film 1 due to heat. May occur.

  The low refractive index layer 13 is formed by curing the coating film by irradiating the coating film on the hard coat layer 12 with ultraviolet rays. As a light source for generating ultraviolet rays, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, a carbon arc lamp, a metal halide lamp, a xenon lamp, an electrodeless discharge tube, or the like can be used.

  The method for producing the antireflection film 1 according to the embodiment of the present invention is characterized in that, in the ultraviolet irradiation step, the cumulative amount of ultraviolet light to be irradiated is in the range of 100 mJ / cm 2 to 400 mJ / cm 2. When the integrated light quantity of the irradiated ultraviolet rays is less than 100 mJ / cm 2, curing is insufficient and the scratch resistance of the low refractive index layer 13 is lowered. On the other hand, when the integrated light quantity of the irradiated ultraviolet rays exceeds 400 mJ / cm 2, the manufacturing cost becomes high.

  The spectral reflectance of the antireflective film 1 of the present invention is performed after the surface opposite to the low refractive index layer 13 of the antireflective film 1 is matted with a black paint, and is applied to the surface of the low refractive index layer 13. The incident angle is set to 5 degrees from the vertical direction, and is obtained under the condition of a 2-degree visual field using a C light source as the light source. The average luminous reflectance is a reflectance value obtained by calibrating the reflectance of each wavelength of visible light with the relative luminous sensitivity and averaging it. At this time, the photopic standard relative visual sensitivity is used as the specific visual sensitivity.

  By setting the haze of the antireflection film 1 of the present invention to 0.4% or less, the antireflection film 1 having a high bright place contrast can be obtained. When the haze exceeds 0.4%, it is possible to apparently suppress light leakage when black is displayed in a dark place due to transmission loss due to scattering, but when displaying black in a bright place. The black display is blurred by scattering and the contrast is lowered.

  By setting the total light transmittance of the antireflection film 1 to 95% or more and 98% or less, the contrast can be improved. In the case where the total light transmittance of the antireflection film 1 is less than 95%, the white luminance when white is displayed is lowered, and the contrast is lowered. On the other hand, it is practically difficult to produce an antireflection film having a total light transmittance exceeding 98% in consideration of back surface reflection and the like. In the antireflection film 1 of the present invention, the total light transmittance is 98% or less. It is characterized by being.

  Furthermore, when the surface roughness is less than 0.3 nm, the effect is small because the surface roughness of the film itself is close. On the other hand, when the surface roughness is larger than 3.0 nm, the effect on black tightening is small, and white blurring appears. The surface roughness is measured with a scanning range of 1 μm square using a scanning probe microscope.

  The antireflection film 1 of the present invention can be suitably used for the display surface. Examples of the display include LCD, PDP, CRT, projection display, EL display and the like. It can also be used inside a display. The case where the antireflection film 1 of the present invention is used as a member of a liquid crystal display will be described below.

  The manufacturing method of the polarizing plate 2 of this invention is demonstrated. FIG. 2 is a conceptual cross-sectional view of the polarizing plate 2 of the present invention. In providing the antireflection film 1 of the present invention on the surface of the transmissive liquid crystal display 6, the polarizing layer 14 and the second transparent layer are formed on the transparent substrate 11 on the opposite side of the antireflective film 1 from the surface on which the low refractive index layer 13 is formed. The substrate 11 needs to be laminated to form the polarizing plate 2. In the polarizing plate 2 of the present invention, the polarizing layer 14 and the second transparent substrate 11 are sequentially formed on the surface of the antireflection film 1 opposite to the surface on which the low refractive index layer 13 is formed, from the transparent substrate 11 side. Laminated. As the polarizing layer 14, for example, stretched polyvinyl alcohol (PVA) to which iodine is added can be used. Moreover, as the other transparent base material 11, the transparent base material 11 used for the antireflection film 1 can be used, and the film which consists of a triacetyl cellulose can be used conveniently.

  FIG. 3 is a conceptual cross-sectional view of a transmissive liquid crystal display 6 using the polarizing plate 4 of the present invention. The transmissive liquid crystal display 6 of the present invention includes a backlight unit 5, a polarizing plate 4, a liquid crystal cell 3, and a polarizing plate 2 in this order. At this time, the polarizing plate 2 side provided with the antireflection film 1 becomes the observation side, that is, the display surface.

  The backlight unit 5 includes a light source and a light diffusion plate. The liquid crystal cell has a structure in which an electrode is provided on one transparent base material 11 and an electrode and a color filter are provided on the other transparent base material 11, and liquid crystal is sealed between both electrodes. The two polarizing plates 4 provided so as to sandwich the liquid crystal cell 3 have a structure in which a transparent substrate 11 and a polarizing layer 14 are sandwiched therebetween.

  Further, the transmissive liquid crystal display 6 of the present invention may include other functional members. Other functional members include, for example, a diffusion film, a prism sheet, a brightness enhancement film for effectively using light emitted from a backlight, and a phase difference film for compensating for a phase difference between a liquid crystal cell and a polarizing plate. However, the transmissive liquid crystal display of the present invention is not limited to these. Moreover, a well-known thing can be used for the backlight unit 5, the polarizing plate 4, the liquid crystal cell 3, etc. FIG.

  As described above, the antireflection film 1 of the present invention is formed. In the antireflection film 1 of the present invention, the polarizing layer 14 and the second transparent substrate 11 are provided on the surface on the transparent substrate 11 side opposite to the side on which the low refractive index layer 13 is formed. Thus, the polarizing plate 4 can be obtained. As the polarizing layer 14, for example, stretched polyvinyl alcohol (PVA) to which iodine is added can be used. Moreover, as the other transparent base material 11, the transparent base material 11 used for the antireflection film 1 can be used, and the film which consists of a triacetyl cellulose can be used conveniently. In the antireflection film 1 and the second transparent base material 11, an alkali saponification treatment is performed before being attached to the polarizing layer 14.

  The alkali saponification treatment is performed by immersing the antireflection film 1 and the second transparent substrate 11 in an alkaline solution, and examples of the alkaline solution include a sodium hydroxide aqueous solution and a potassium hydroxide aqueous solution.

  In the antireflection film 1 of the present invention, when the antireflection film 1 is formed into a polarizing plate, the antireflection film is immersed in an alkaline solution in a state where the low refractive index layer 13 is in contact with the alkaline solution and saponified. Even if it performs, it can be set as the antireflection film 1 excellent in the saponification resistance that an optical characteristic and scratch resistance do not change.

  The antireflection film 1 of the present invention is formed into a polarizing plate, and further provided so that the low refractive index layer 13 is the outermost surface on the front side of the transmissive liquid crystal display 6, that is, the observation side.

  EXAMPLES The present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples.

Nine types of low refractive index coating liquids were prepared by sequentially increasing the ratio of the solid weight of the low refractive index nanoparticles to the ultraviolet curable material. The coating solution for low refractive index is EO-modified dipentaerythritol hexaacrylate (trade name: DPEA-12, manufactured by Nippon Kayaku Co., Ltd.), which is an ultraviolet curable material, polymerization initiator (trade name; manufactured by BASF Corp .; Irgacure 184). , Alkylpolyether-modified silicone oil (product name: TSF4460, manufactured by Momentive Performance Materials Japan GK), solvent (isopropyl alcohol, methyl isobutyl ketone) ratio is constant, and low refractive index nanoparticle dispersion (inside The addition amount of low refractive index silica particles having voids: average particle diameter of 50 nm, solid content of 20%, solvent: methyl isobutyl ketone) was sequentially changed.
<Low refractive index coating liquid>
・ Low refractive index nano fine particle dispersion ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ X parts by weight ・ EO modified dipentaerythritol hexaacrylate ・ ・ ・ ・ ・ ・ 1. 99 parts by weight ・ Polymerization initiator ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 0.07 parts by weight ・ Alkyl polyether modified silicone oil ・ ・ ・ ・ ・ ・・ ・ ・ ・ ・ ・ 0.20 parts by weight ・ Solvent (Isopropyl alcohol) ・ ・ ・ ・ ・ ・ 72.20 parts by weight ・ Solvent (Methyl isobutyl ketone) ・ ・ ・ ・ ・ ・·································································································································· ), 6.225 parts by weight (0.6), 7.47 parts by weight (0.8), 1.245 parts by weight (0.1) 9 types of low refraction: 2.49 parts by weight (0.3), 9.96 parts by weight (1.0), 12.45 parts by weight (1.3), 14.94 parts by weight (1.5) A nano-particle dispersion was prepared.

  The ratio of the solid weight of the low refractive index nanoparticle to the ultraviolet curable material is 20%, which is the solid content of the low refractive index nanoparticle dispersion with respect to the weight part of EO-modified dipentaerythritol hexaacrylate.

  Subsequently, a low-refractive-index layer-forming coating solution prepared on a triacetyl cellulose film (Fuji Film: film thickness: 80 μm) having a hard coat layer obtained by curing a polyfunctional monomer having a (meth) acryloyloxy group. Was applied and dried in an oven at 70 ° C. for 40 seconds to form a film thickness of 100 nm. After drying, an ultraviolet irradiation device (Fusion UV System Japan, light source H bulb) was used under a nitrogen purge to cure by irradiation with ultraviolet rays at an irradiation dose of 380 mJ / m 2 to form a low refractive index layer.

  The low-refractive-index nanoparticle dispersion is 3.735 parts by weight (ratio 0.4 with respect to the ultraviolet curable material), 4.98 parts by weight (0.5), 6.225 parts by weight (0.6), and 7. An antireflection film having a low refractive index layer prepared by applying 47 parts by weight (0.8) of a coating liquid was prepared, and Examples 1, 2, 3, and 4 were obtained. 1.245 parts by weight (0.1), 2.49 parts by weight (0.3), 9.96 parts by weight (1.0), 12.45 parts by weight (1.3), 14.94 parts by weight ( 1.5), an antireflection film having a low refractive index layer prepared by applying the coating liquid was prepared, and Comparative Examples 1, 2, 3, 4, and 5 were obtained.

The antireflection films of Examples 1 to 4 and Comparative Examples 1 to 5 were evaluated by the following method.
<Alkali resistance>
The obtained antireflection film was immersed in a 1.5 N aqueous sodium hydroxide solution, and then the surface state of the antireflection film when the surface was washed with water was visually evaluated. An antireflection film with no peeling of the coating film (low refractive index layer) was marked with a circle, and a film with peeling was marked with a cross.
<Optical characteristics: spectral reflectance / average luminous reflectance>
About the surface of the low refractive index layer of the obtained antireflection film, the spectral reflectance at an incident angle of 5 ° was measured using an automatic spectrophotometer (manufactured by Hitachi, Ltd., U-4000). Further, the average luminous reflectance was obtained from the obtained spectral reflectance curve. In the measurement, a matte black paint was applied to the surface of the triacetylcellulose film, which is a transparent substrate, on which the low refractive index layer was not formed, and an antireflection treatment was performed.
<Haze value and total light transmittance>
About the obtained antireflection film, the haze value and the total light transmittance were measured using the image clarity measuring device [Nippon Denshoku Industries Co., Ltd. make, NDH-2000].
<Anti-fouling property: contact angle measurement>
Using a contact angle meter (CA-X type: manufactured by Kyowa Interface Science Co., Ltd.), a droplet of 0.9 μl was formed on the needle tip, and this was brought into contact with the surface of the substrate (solid) to form a droplet. The contact angle is an angle formed by the solid surface and the tangent to the liquid surface at the point where the solid and the liquid are in contact with each other, and is defined as the angle containing the liquid. Distilled water was used as the liquid.
<Wipeability of oil-based pens (Mackey, Magic)>
Two types of oil-based pens (“Mckey Extra Fine” (registered trademark) Zebra Co., Ltd./“Magic Ink (No. 500 fine book) ”(registered trademark) Teranishi Chemical Industry Co., Ltd.) were prepared.

  Using each of the prepared oil-based pens, the oil-based pen attached to the substrate surface was wiped off with a tissue paper [Erière (registered trademark), manufactured by Daio Paper Co., Ltd.], and the ease of removal was visually evaluated. Judgment criteria are shown below.

      ○: The oil pen can be easily wiped off.

      Δ: The oil pen can be wiped off.

X: The oil-based pen cannot be wiped off.
<Mechanical properties: scratch resistance test>
The surface of the substrate was rubbed 10 times at 200 g / cm 2, 300 g / cm 2, 400 g / cm 2, and 500 g / cm 2 with steel wool (Bonster # 0000 (registered trademark): manufactured by Nippon Steel Wool), and the presence or absence of scratches was visually evaluated. (Steel wool test).

  Judgment criteria are shown below.

○: No scratch ×: Scratch <Confirmation of bleed out>
Wipe the coated surface with tissue paper [Erière (registered trademark), manufactured by Daio Paper Co., Ltd.], and check if the area is wiped and not wiped on the coated surface visually under fluorescent light. evaluated.

  Judgment criteria are shown below.

○: No bleed (the wiped part cannot be visually confirmed)
×: Bleed (wiped area can be confirmed visually)
<Surface roughness>
Using a scanning probe microscope (Dimension D3100, manufactured by Nippon Beco Co., Ltd.), measurement was performed in a scanning range of 1 μm square.

  Table 1 shows the evaluation results of the antireflection films 1 of Examples 1 to 4 and Comparative Examples 1 to 5.

As a result of evaluation, Examples 1 to 4 in which the low refractive index layer is in the range of 0.4 part by weight or more and less than 0.8 part by weight with respect to 1 part by weight of the UV curable material and the UV curable material. As for the optical characteristics, the average luminous reflectance is from 0.3% to 2.5%, the total light transmittance is from 95% to 98%, and the haze is from 0.01% to 0.40. % And the surface roughness (Ra) satisfies all of the range of 0.3 nm to 3.0 nm. Furthermore, it was found that saponification treatment is possible even in a state where the antifouling property and alkali resistance are excellent and no protective film is attached.

DESCRIPTION OF SYMBOLS 1 ... Antireflection film 2 ... Polarizing plate 3 ... Liquid crystal cell 4 ... Polarizing plate 5 ... Backlight unit 6 ... Transmission-type liquid crystal display 11 ... Transparent base material 12 ... Hard coat layer 13 ... Low refractive index layer 14 ... Polarizing layer

Claims (6)

In an antireflection film in which a hard coat layer and a low refractive index layer are laminated on one surface of a transparent substrate,
The hard coat layer is formed of a polymer mainly composed of a polyfunctional monomer having a (meth) acryloyloxy group,
And the low refractive index layer is formed from a low refractive index coating agent comprising at least an ultraviolet curable material and low refractive index particles,
In addition, the low refractive index layer includes an ultraviolet curable material and low refractive index nano-particles in a range of 0.4 parts by weight or more and less than 0.8 parts by weight with respect to 1 part by weight of the ultraviolet curable material. An antireflection film produced from a low-refractive index coating agent.   The antireflection film according to claim 1, wherein the antireflection film is subjected to alkali saponification treatment.   The average luminous reflectance is from 0.3% to 2.5%, the total light transmittance is from 95% to 98%, and the haze is from 0.01% to 0.40%, And the surface roughness (Ra) satisfy | fills all in the range of 0.3 nm or more and 3.0 nm or less, The antireflection film of Claim 1 or Claim 2 characterized by the above-mentioned.   The low refractive index layer was dried at a drying temperature within the range of −20 ° C. or higher and + 20 ° C. or lower of the boiling point of the main solvent, and was manufactured by ultraviolet irradiation within an integrated light amount range of 100 mJ / cm 2 or more and 400 mJ / cm 2 or less. The antireflection film according to any one of claims 1 to 3, wherein   5. The reflection comprising the antireflection film according to claim 1, wherein a polarizing layer and a second transparent substrate are sequentially provided on the low refractive index layer-free surface of the transparent substrate. Preventive polarizing plate.   The antireflective polarizing plate according to claim 5, the liquid crystal cell, the second polarizing plate, and the backlight unit are provided in this order from the observer side, and the low refractive index layer non-formation surface of the antireflective polarizing plate A transmissive liquid crystal display characterized in that a liquid crystal cell is held on the side.