JP2014056066A - Antireflection film and production method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an antireflection film which has a low refractive index layer having a refractive index of less than 1.30 and which has a further enhanced antireflection effect, and to obtain a transmissive liquid crystal display using the antireflection film.SOLUTION: An antireflection film (1) includes at least a low refractive index layer (15) on a transparent substrate. The low refractive index layer comprises a binder resin and fine particles, and the surface of the low refractive index layer has an arithmetic average roughness (Ra) of 3 nm or more and 8 nm or less. The fine particles have an average primary particle diameter of 20 nm or more and 300 nm or less. An area occupation rate of the fine particles with respect to the low refractive index layer is higher than an area occupation rate of the binder resin with respect to the low refractive index layer. A transmissive liquid crystal display using the antireflection film is also disclosed.

Description

  The present invention relates to an antireflection film provided on the surface of a window or a display. In particular, the present invention relates to an antireflection film provided on the surface of a display such as a liquid crystal display (LCD), a CRT display, an organic electroluminescence display (ELD), a plasma display (PDP), a surface electric field display (SED), or a field emission display (FED). . In particular, it relates to an antireflection film provided on the LCD surface. Furthermore, the present invention relates to an antireflection film provided on the transmissive LCD surface.

  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 essential to provide an antireflection function on the display surface, etc.By providing an antireflection film on the display surface, reflection of external light can be suppressed by the antireflection function, and contrast in a bright place can be increased. Can be improved.

  In general, an antireflection film can be obtained by forming an antireflection layer having a multilayer structure having a repeating structure of a high refractive index layer and a low refractive index layer made of a transparent material such as a metal oxide on a transparent substrate. These antireflection layers having a multilayer structure can be formed by a dry film forming method such as a chemical vapor deposition (CVD) method or a physical vapor deposition (PVD) method. However, since the transparent substrate and each layer are required to have low birefringence, usable materials are limited.

  In the case of forming an antireflection layer using a dry film formation method, there is an advantage that the film thickness of the low refractive index layer and the high refractive index layer can be precisely controlled, but the film formation is performed in a vacuum. There is a problem that productivity is low and it is not suitable for mass production. On the other hand, as a method for forming an antireflection layer, attention has been focused on production of an antireflection film by a wet film formation method using a coating liquid capable of increasing the area, continuously producing, and reducing the cost.

  In addition, in the production of an antireflection film by a wet film-forming method using a coating liquid, since the form is a thin film, a hard coat layer generally obtained by curing an acrylic material in order to impart surface hardness is used. A method is used in which a next layer is formed thereon. The hard coat layer is made of an acrylic material and has high surface hardness, gloss, transparency, and scratch resistance. Such a film can simultaneously provide a surface protection function in addition to an antireflection function.

  When an antireflection layer is formed by a wet film formation method, it is produced by applying at least a low refractive index layer on a hard coat layer obtained by curing these ionizing radiation curable materials. Compared to the membrane method, it has the merit of being able to be manufactured at low cost, and is widely available in the market.

JP-A-2005-202389 JP 2005-199707 A JP-A-11-92750 JP 2007-121993 A JP 2005-144849 A JP 2006-159415 A JP 2010-008863 A JP 2010-085682 A International Publication WO2010 / 038709 Pamphlet

  In order to enhance the antireflection function, it is necessary to form the outermost layer with a material having a lower refractive index. However, the refractive index is a value unique to the substance determined from the dielectric constant and the magnetic permeability. Even if a fluorine-based material or a hollow material generally having a low refractive index is used, the refractive index is about 1.32, and a transparent solid layer having a refractive index of less than 1.30 is formed using an existing material. There is a problem that it is extremely difficult to do. An object of the present invention is to solve the problem and provide an antireflection film having a low refractive index layer having a refractive index of less than 1.30 and further enhancing the antireflection effect, and a method for producing the same. Another object of the present invention is to provide an antireflection polarizing plate and a transmissive liquid crystal display that use the antireflection film and have an excellent antireflection function.

In order to solve the above-mentioned problem, the invention according to claim 1 is an antireflection film having a low refractive index layer on at least a transparent substrate, wherein the low refractive index layer comprises a binder resin and fine particles, The arithmetic average roughness (Ra) of the surface of the refractive index layer is 3 nm or more and 8 nm or less, the average primary particle diameter of the fine particles is 20 nm or more and 300 nm or less, and the area occupation ratio of the fine particles to the low refractive index layer is It is an antireflection film characterized by being higher than the area occupation ratio of the binder resin to the low refractive index layer.
The invention according to claim 2 is the antireflection film according to claim 1, wherein the haze is 0.1% or more and 1.0% or less.
The invention according to claim 3 is the antireflection film according to claim 1 or 2, wherein the fine particles are silica particles.
The invention according to claim 4 is the antireflection film according to any one of claims 1 to 3, wherein the fine particles are hollow silica particles.
The invention according to claim 5 has at least a hard coat layer, a high refractive index layer, and the low refractive index layer in this order on the transparent substrate. The antireflection film according to Item 1.
The invention described in claim 6 is an antireflection polarizing plate using the antireflection film according to any one of claims 1 to 5, wherein the low refractive index layer of the transparent substrate is provided. An antireflection polarizing plate having a second transparent substrate and a first polarizing layer in this order on the opposite side of the formed surface.
The invention according to claim 7 includes the antireflection polarizing plate according to claim 6, the liquid crystal cell, the second polarizing plate, and the backlight unit in this order from the observer side. A transmissive liquid crystal display characterized by the above.
The invention according to claim 8 is a method for producing the antireflection film according to any one of claims 1 to 5 in a wet process,
A coating film forming step of applying a low refractive index layer-forming coating liquid containing a binder resin and fine particles on a transparent substrate, and forming a coating film,
A drying step of drying the coating film;
Curing by irradiating with ionizing radiation after drying the coating film, and forming a low refractive index layer with a thickness of 50 nm or more and 150 nm or less,
It is a manufacturing method of the antireflection film characterized by having.

  The antireflection film according to the present invention has a low refractive index layer having a refractive index of less than 1.30, and the antireflection effect is further enhanced. If the antireflection film is used, an antireflection polarizing plate and a transmissive liquid crystal display with less reflection can be obtained.

It is a cross-sectional schematic diagram of the antireflection film of one Example of this invention. It is the schematic of the manufacturing process of the antireflection film of one Example of this invention. It is a cross-sectional schematic diagram of the anti-reflective polarizing plate using the anti-reflective film of one Example of this invention. It is a cross-sectional schematic diagram which shows a transmissive liquid crystal display provided with the antireflection film of one Example of this invention.

  FIG. 1 shows a schematic cross-sectional view of the antireflection film (1) of the present invention.

  The antireflection film (1) of the present invention is characterized in that a low refractive index layer (15) is provided on at least one surface of the transparent substrate (11). In some cases, the lower layer of the low refractive index layer (15) may be provided with a single layer of the hard coat layer (12) and the high refractive index layer (14) or a multilayer structure combining these layers.

  First, the transparent substrate (11) will be described.

  As the transparent substrate in the antireflection film of the present invention, 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. And those made of organic polymers such as acrylic, cycloolefin such as cycloolefin polymer, polystyrene, polyvinyl chloride, polyimide, polyvinyl alcohol, polycarbonate, ethylene vinyl alcohol and the like. 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. The thickness of the transparent substrate is preferably 10 μm or more and 120 μm or less. Moreover, when using triacetylcellulose, it is preferable to use the thickness of 25 micrometers or more and 80 micrometers or less. Moreover, when using a polyethylene terephthalate, it is preferable to use the thickness of 20 micrometers or more and 80 micrometers or less.

  Especially, since a triacetylcellulose film has little birefringence and favorable transparency, when using the antireflection film 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. In general, a polyethylene terephthalate film widely used as a transparent substrate is about 1.60.

  Next, the low refractive index layer (15) will be described.

  The low refractive index layer of the present invention comprises a binder resin (16) and fine particles (17).

  The low refractive index layer of the present invention is characterized in that the refractive index of the low refractive index layer with respect to a light source of 589 nm is 1.25 or more and less than 1.30. By setting the refractive index of the low refractive index layer within the range of 1.25 or more and less than 1.30, a high-performance antireflection function can be provided. When the refractive index exceeds 1.30, the obtained antireflection film does not have a sufficient antireflection function. Accordingly, the refractive index of the low refractive index layer is preferably lower, but when a low refractive index layer lower than 1.25 is formed by using the method of the present invention, the layer does not have sufficient mechanical strength. .

  The optical film of the present invention is characterized in that the arithmetic average roughness (Ra) of the surface of the low refractive index layer is in the range of 3 nm to 8 nm. In the present invention, by controlling the surface roughness of the low refractive index layer, an arbitrary unevenness (air layer) is provided in the material to realize a low refractive index. When the arithmetic average roughness is less than 3 nm, the refractive index is almost the same as the refractive index of the constituent material because the surface is smooth, and the refractive index of less than 1.30 cannot be satisfied. . On the other hand, when the surface roughness exceeds 8 nm, it does not function as a film because it does not have physical or chemical resistance with increasing brittleness and specific surface area. In order to achieve a low refractive index, the average primary particle diameter of the fine particles is preferably 20 nm or more and 300 nm or less.

  In the low refractive index layer of the present invention, the area occupancy of the fine particles (17) is higher than the area occupancy of the binder resin (16) forming material. As a result, the low refractive index layer has a surface roughness according to the particle size of the fine particles. The area occupation ratio can be obtained by observing the cross section of the low refractive index layer with a transmission electron microscope. At this time, when the fine particles are hollow, the area indicates a range including the internal air layer. More preferably, the area occupation ratio of the fine particles is 80% or more, for example, 80% or more and 99% or less, whereby the specific surface area in the layer is increased and a layer having a lower refractive index can be formed.

  Examples of the fine particles in the low refractive index layer of the present invention include silica particles, preferably hollow silica particles. In the hollow silica particles, since the void portion can have the refractive index of air (≈1), a very low refractive index can be imparted. As the hollow silica particles, porous silica particles or silica particles having a shell (shell) structure can be used. The voids inside the hollow silica particles are, for example, 20 nm or more and 200 nm or less. An organic silicon material having voids inside can also be used. The voids preferably have an average diameter of 20 nm to 150 nm. When the average diameter exceeds 150 nm, light is remarkably reflected by Rayleigh scattering, the low refractive index layer is whitened, and the transparency of the antireflection film tends to be lowered. On the other hand, when the average diameter is less than 20 nm, a layer structure having a high refractive index is formed, and the average luminous reflectance is increased.

  The antireflection film of the present invention preferably has a haze of 0.1% to 1.0%. The haze is influenced by the surface roughness of the layer due to the film structure. When the haze is less than 0.1%, the above-described surface roughness cannot be satisfied. On the other hand, when the haze exceeds 1.0%, the effect of surface scattering is increased and the transparency of the layer is impaired.

  In order for the antireflection film to exhibit a sufficient antireflection function, the film thickness (d) of the low refractive index layer is obtained by multiplying the film thickness (d) by the refractive index (n) of the low refractive index layer. The film thickness (nd) is designed to be equal to ¼ of the wavelength of visible light. Therefore, the film thickness of the low refractive index layer is preferably 50 nm or more and 150 nm or less.

  Examples of the binder resin include acrylic materials.

  The low refractive index layer made of the above materials can be formed by coating and coating by a wet film forming method.

  Next, the hard coat layer (12) will be described.

  The hard coat layer of the present invention is made of an acrylic material that is an ionizing radiation curable material.

  In the antireflection film of the present invention, the thickness of the hard coat layer to be formed is preferably 3 μm or more and 10 μm or less, and the pencil hardness is H or more in order to provide physical scratch resistance. It is preferable. When the film thickness is too thin, the pencil hardness is not achieved, and when it is too thick, the curvature of the film due to internal stress due to curing becomes significant.

  Next, the high refractive index layer (14) will be described.

  The high refractive index layer is made of a photocurable material such as the aforementioned acrylic material, which is an ionizing radiation curable material. Metal fine particles may be added to the photocurable material, and an arbitrary refractive index can be selected by changing the mixing ratio of the photocurable material and the metal fine particles.

  At this time, in order for the antireflection film to exhibit a sufficient antireflection function, the film thickness (D) of the high refractive index layer is obtained by multiplying the film thickness (D) by the refractive index (N) of the low refractive index layer. The optical film thickness (ND) is designed to be equal to ½ of the wavelength of visible light. Note that the high refractive index layer of the present invention preferably has a film thickness of 100 nm to 200 nm, and the refractive index is preferably 1.50 to 1.70 when a light source of 589 nm is used. By setting the film thickness and refractive index to these values, the reflection color of the antireflection film can be made less colored. These are formed by a wet film forming method in which a coating solution for forming a high refractive index layer is applied.

  Below, an example of the formation method of an antireflection film is shown.

  First, the formation method of a hard-coat layer (12) is shown.

  First, a coating liquid for forming a hard coat layer is formed by applying a coating liquid for forming a hard coat layer on the transparent substrate (11). The coating method for applying the coating liquid for forming the hard coat layer onto the transparent substrate includes a roll coater, a reverse roll coater, a gravure coater, a micro gravure coater, a knife coater, a bar coater, a wire bar coater, and a die coater. A coating method using a dip coater can be used.

  The hard coat layer-forming coating solution may contain an acrylic material that is an ionizing radiation curable material. Polyfunctional urethane (meth) synthesized from polyfunctional (meth) acrylate compounds such as polyhydric alcohol acrylic acid or methacrylic acid ester, diisocyanate and polyhydric alcohol and acrylic acid or methacrylic acid hydroxy ester Acrylate compounds 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. .

  In the present invention, “(meth) acrylate” indicates both “acrylate” and “methacrylate”, and compounds containing both monofunctional and polyfunctional compounds thereof. For example, “urethane (meth) acrylate” indicates both “urethane acrylate and urethane methacrylate” and compounds containing both monofunctional and polyfunctional groups thereof.

  Moreover, in the coating liquid for hard-coat layer formation, the photoinitiator may be included. Apply a coating liquid for forming a hard coat layer on a transparent substrate by wet film formation to form a coating film, and then use ultraviolet light as ionizing radiation. A polymerization initiator is added. Examples of the photopolymerization initiator include acetophenones, benzoins, benzophenones, phosphine oxides, ketals, anthraquinones, thioxanthones, and the like. In addition, n-butylamine, triethylamine, poly-n-butylphosphine, or the like can be used as a photosensitizer.

  Further, the coating liquid for forming the hard coat layer may contain an antistatic agent. Quaternary ammonium salts or metal oxide fine particles or conductive polymers can be used.

  Moreover, a solvent is added to the coating liquid for forming a hard coat layer as necessary. By adding a solvent, coating suitability can be improved. Solvents include aromatic hydrocarbons such as toluene, xylene, cyclohexane and cyclohexylbenzene, hydrocarbons such as n-hexane, hexadecane and ethylcyclohexane, dibutyl ether, dimethoxymethane, dimethoxyethane, diethoxyethane, propylene oxide, Ethers such as dioxane, dioxolane, trioxane, tetrahydrofuran, anisole and phenetole, and methyl isobutyl ketone, methyl butyl ketone, acetone, methyl ethyl ketone, diethyl ketone, dipropyl ketone, diisobutyl ketone, cyclopentanone, cyclohexanone, methylcyclohexanone, and Ketones such as methylcyclohexanone, ethyl formate, propyl formate, n-pentyl formate, methyl acetate, ethyl acetate, Esters such as methyl lopionate, ethyl propionate, n-pentyl acetate, and γ-butyrolactone, and cellosolves such as methyl cellosolve, ethyl cellosolve, butyl cellosolve, cellosolve acetate, methanol, ethanol, n-propyl alcohol, isopropyl It is appropriately selected from alcohols such as alcohol and ethylene glycol, water and the like in consideration of coating suitability and the like.

  In the hard coat layer forming coating liquid, an addition called a surface conditioner is applied to prevent the occurrence of coating film defects such as repellency and unevenness in the formed coating film by applying the hard coating layer forming coating liquid. An agent may be added. The surface modifier is also called a leveling agent, an antifoaming agent, an interfacial tension modifier, or a surface tension modifier depending on its function, and all have a function of changing the surface tension of the coating film to be formed.

  In addition, in the coating liquid for forming a hard coat layer, other additives may be added to the coating liquid in addition to the surface conditioner described above. As the functional additive, an antistatic agent, an ultraviolet absorber, an infrared absorber, an adhesion improver, a curing agent, or the like can be used.

  Next, the solvent in the coating film is removed by drying the hard coating layer coating film formed on the transparent substrate using the coating liquid for forming the hard coating layer. At this time, heating, blowing, hot air, or the like can be used as the drying means.

Next, the hard coat layer is hardened by irradiating with ionizing radiation. 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 ultraviolet curing, the peak illuminance is preferably 100 to 500 mW / cm ² and the integrated light quantity is preferably 50 to 800 mJ / cm ² . In the case of ultraviolet curing, the treatment may be performed in a nitrogen-substituted atmosphere. When radical polymerization is the main reaction, inhibition of curing due to oxygen can be suppressed. 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. . The electron beam preferably has an energy of 50 to 1000 keV. An electron beam having an energy of 100 to 300 keV is more preferable.

  Next, a method for forming the high refractive index layer (14) will be described.

  First, a coating liquid for forming a high refractive index layer is formed by applying a coating solution for forming a high refractive index layer to the transparent substrate (11) or the hard coat layer (12) formed on the substrate. As a coating method at this time, a coating method using a roll coater, a reverse roll coater, a gravure coater, a micro gravure coater, a knife coater, a bar coater, a wire bar coater, a die coater, or a dip coater can be used.

  The coating liquid for forming a high refractive index layer may contain a photocurable material made of an acrylic material that is an ionizing radiation curable material. Examples of the acrylic material for the coating liquid for forming the high refractive index layer include polyfunctional (meth) acrylate compounds such as acrylic acid or methacrylic acid ester of polyhydric alcohol, diisocyanate and polyhydric alcohol, and acrylic acid or methacrylic acid. A polyfunctional urethane (meth) acrylate compound as synthesized from a hydroxy ester or the like 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. .

  In addition, the coating liquid for forming a high refractive index layer may contain a photopolymerization initiator. When ultraviolet rays are used as ionizing radiation and the coating film is cured by ultraviolet irradiation, a photopolymerization initiator is added to the coating solution. Examples of the photopolymerization initiator include acetophenones, benzoins, benzophenones, phosphine oxides, ketals, anthraquinones, thioxanthones, and the like. In addition, n-butylamine, triethylamine, poly-n-butylphosphine, or the like can be used as a photosensitizer.

  In the coating liquid for forming a high refractive index layer, metal fine particles may be added to the photocurable material. Specific metal fine particles include zirconium oxide, antimony pentoxide, titanium oxide, tin-doped indium oxide (ITO ) Antimony-doped tin oxide (ATO), magnesium fluoride, silica and the like can be used.

  Further, a coating liquid for forming a high refractive index layer may be formed of an acrylic material alone. As a technique for realizing a high refractive index with an acrylic material alone, an acrylic ester or a methacrylic ester having an aromatic ring can be used.

  Moreover, a solvent is added to the coating liquid for forming a high refractive index layer as necessary. By adding a solvent, coating suitability can be improved. Solvents include aromatic hydrocarbons such as toluene, xylene, cyclohexane and cyclohexylbenzene, hydrocarbons such as n-hexane, ethylcyclohexane and hexadecane, dibutyl ether, dimethoxymethane, dimethoxyethane, diethoxyethane, propylene oxide, Ethers such as dioxane, dioxolane, trioxane, tetrahydrofuran, anisole and phenetole, and methyl isobutyl ketone, methyl butyl ketone, acetone, methyl ethyl ketone, diethyl ketone, dipropyl ketone, diisobutyl ketone, cyclopentanone, cyclohexanone, methylcyclohexanone, and Ketones such as methylcyclohexanone, ethyl formate, propyl formate, n-pentyl formate, methyl acetate, ethyl acetate, Esters such as methyl lopionate, ethyl propionate, n-pentyl acetate, and γ-butyrolactone, and cellosolves such as methyl cellosolve, ethyl cellosolve, butyl cellosolve, cellosolve acetate, methanol, ethanol, n-propyl alcohol, isopropyl It is appropriately selected from alcohols such as alcohol and ethylene glycol, water and the like in consideration of coating suitability and the like.

  Next, the solvent in the coating film is removed by drying the formed high refractive index layer coating film. At this time, heating, blowing, hot air, or the like can be used as the drying means.

Next, the high refractive index layer is hardened by irradiating with ionizing radiation. As the ionizing radiation, ultraviolet rays and electron beams can be used. The process can be appropriately selected according to the characteristics of the paint. 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 ultraviolet curing, the peak illuminance is preferably 100 to 500 mW / cm ² and the integrated light quantity is preferably 50 to 800 mJ / cm ² . In the case of ultraviolet curing, the treatment may be performed in a nitrogen-substituted atmosphere. When radical polymerization is the main reaction, inhibition of curing due to oxygen can be suppressed. 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. . The electron beam preferably has an energy of 50 to 1000 keV. An electron beam having an energy of 100 to 300 keV is more preferable.

  Next, a method for forming the low refractive index layer (15) will be described.

  First, a coating solution for forming a low refractive index layer is made of a transparent substrate (11), a hard coat layer (12) formed on the substrate, or a high refractive index layer (on the substrate or hard coat layer ( 14) Apply on top to form a low refractive index layer coating. As a coating method at this time, a coating method using a roll coater, a reverse roll coater, a gravure coater, a micro gravure coater, a knife coater, a bar coater, a wire bar coater, a die coater, or a dip coater can be used.

  The coating liquid for forming a low refractive index layer may contain inorganic fine particles and a binder resin material. At this time, an arbitrary surface roughness can be formed by adjusting the ratio between the amount of inorganic fine particles and the amount of binder resin.

  Specifically, the mass ratio of the binder resin in the binder matrix composed of the inorganic fine particles and the binder resin is preferably 20% or less. More preferably, it is 10% or less, and this value can be appropriately selected according to the refractive index of the inorganic fine particles.

  At this time, surface treatment may be applied to fine particles, for example, inorganic fine particles, in order to control the compatibility with the binder resin. Specific surface treatments include alkoxysilanes such as methyltriethoxysilane, tetraethoxysilane, vinyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, and 3-acryloxypropyltrimethoxysilane, hexamethyldisilazane, etc. A surface modification method using silazanes may be used.

  Specific acrylic materials used in the coating liquid for forming the low refractive index layer include polyfunctional (meth) acrylate compounds such as polyhydric alcohol acrylic acid or methacrylic acid ester, diisocyanate, polyhydric alcohol and acrylic acid. Alternatively, a polyfunctional urethane (meth) acrylate compound synthesized from a hydroxy ester of methacrylic acid or the like 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. .

  Moreover, in the coating liquid for low refractive index layer formation, the photoinitiator may be included. When ultraviolet rays are used as ionizing radiation and the coating film is cured by ultraviolet irradiation, a photopolymerization initiator is added to the coating solution. Examples of the photopolymerization initiator include acetophenones, benzoins, benzophenones, phosphine oxides, ketals, anthraquinones, thioxanthones, and the like. In addition, n-butylamine, triethylamine, poly-n-butylphosphine, or the like can be used as a photosensitizer.

  In addition, an arbitrary solvent can be added to the coating solution for forming a low refractive index layer. Specifically, alcohols such as methanol, ethanol, n-propyl alcohol, isopropyl alcohol, and ethylene glycol, aromatic hydrocarbons such as toluene, xylene, cyclohexane, cyclohexylbenzene, hydrocarbons such as n-hexane, di Ethers such as butyl ether, dimethoxymethane, dimethoxyethane, diethoxyethane, propylene oxide, dioxane, dioxolane, trioxane, tetrahydrofuran, fluoroether, anisole and phenetole, and methyl isobutyl ketone, methyl butyl ketone, acetone, methyl ethyl ketone, diethyl ketone , Dipropyl ketone, diisobutyl ketone, cyclopentanone, cyclohexanone, methylcyclohexanone, and methylcyclohexano Ketones such as ethyl formate, propyl formate, n-pentyl formate, methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, n-pentyl acetate, and γ-butyrolactone, and methyl cellosolve In addition, cellosolves such as ethyl cellosolve, butyl cellosolve, cellosolve acetate and the like are appropriately selected in consideration of coating suitability and the like. In addition, a surface conditioner may be used as an additive. The surface conditioner is also referred to as a leveling agent, an antifoaming agent, an interfacial tension adjuster, or a surface tension adjuster depending on the function of the surface conditioner, and it is possible to control the surface tension of the coating film to be formed.

  A low refractive index layer can be formed by applying a coating solution for forming a low refractive index layer obtained by preparing the above materials onto each layer by a wet film forming method. In the case of using an ionizing radiation curable material as the binder resin, a low refractive index layer can be formed by irradiating with ionizing radiation and hardening after drying the coating film as necessary. it can.

As the ionizing radiation at this time, ultraviolet rays or electron beams can be used. The process can be appropriately selected according to the characteristics of the paint. 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 ultraviolet curing, the peak illuminance is preferably 100 to 500 mW / cm ² and the integrated light quantity is preferably 50 to 800 mJ / cm ² . In the case of ultraviolet curing, the treatment may be performed in a nitrogen-substituted atmosphere. When radical polymerization is the main reaction, inhibition of curing due to oxygen can be suppressed. 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. . The electron beam preferably has an energy of 50 to 1000 keV. An electron beam having an energy of 100 to 300 keV is more preferable.

  The antireflection film of the present invention is continuously formed by a roll-to-roll method. FIG. 2 is a schematic view of a production process of an antireflection film according to one embodiment of the present invention, in which a web-like transparent substrate that has been wound is continuously run from an unwinding portion (31) to a winding portion (32). At this time, the transparent substrate (11) passes through the coating unit (coating step (21)), the heating / drying unit (heating / drying step (22)), and the ionizing radiation irradiation unit (hardening step (23)). By doing so, the hard coat layer (12) is continuously formed on the transparent substrate (11). Thereafter, the high refractive index layer (14) and the low refractive index layer (15) are similarly passed from the coating to the hardening step, so that the high refractive index layer (14) and the low refractive index are formed on the hard coat layer (12). An antireflection film (1) can be produced with the rate layer (15). When the hard coat layer is formed, it is wound on a roll, and when the low refractive index layer is formed, the low refractive index layer may be formed again by a roll-to-roll method, or continuously after the hard coat layer is formed. Alternatively, a low refractive index layer may be formed and wound on a roll.

  As described above, the antireflection film of the present invention can be obtained.

  Next, the antireflection polarizing plate (510) using the antireflection film (1) of the present invention will be described.

  FIG. 3 is a schematic cross-sectional view of an antireflective polarizing plate using the antireflective film of one embodiment of the present invention. The antireflective polarizing plate (510) of FIG. ) Is provided with a hard coat layer (12), a high refractive index layer (14), and a low refractive index layer (15) in this order, and the first polarizing layer ( 53) and a transparent base material (52) in this order, an antireflection polarizing plate (510).

  The antireflection film (1) according to the embodiment of the present invention can be used as a part of a display member or an image device.

  Next, the configuration of a transmissive liquid crystal display using the antireflection film of the present invention will be described.

  FIG. 4 is a schematic cross-sectional view showing a transmissive liquid crystal display including the antireflection film of one embodiment of the present invention. In the transmissive liquid crystal display of FIG. 500), a liquid crystal cell (60), a second polarizing plate (70), and a backlight unit (80). The 1st polarizing plate (50) is provided in the low refractive index layer non-formation surface. At this time, the antireflection film (1) side becomes the observation side, that is, the display surface.

  In Fig.4 (a), it becomes a transmissive | pervious liquid crystal display provided with the transparent base material (11) of an antireflection film (1), and the transparent base material (51) of a 1st polarizing plate (50) separately. Yes.

  The backlight unit (80) includes a light source and a light diffusion plate. The liquid crystal cell (60) has a structure in which an electrode is provided on one transparent substrate, an electrode and a color filter are provided on the other transparent substrate, and liquid crystal is sealed between both electrodes. In the first and second polarizing plates provided so as to sandwich the liquid crystal cell (60), the polarizing layer (53, 73) is sandwiched between the transparent substrates (51, 52, 71, 72). It has become.

  Moreover, in FIG.4 (b), the anti-reflective polarizing plate (510) of this invention, the liquid crystal cell (60), the 2nd polarizing plate (70), and the backlight unit (80) are provided in this order. Yes. At this time, the low refractive index layer (15) side of the antireflection film (1) is the observation side, that is, the display surface.

  In FIG. 4B, a polarizing layer (53) and a transparent substrate (52) are provided in this order as a first polarizing plate on the surface of the antireflective film (1) where the low refractive index layer is not formed. A transmissive liquid crystal display provided with the antireflection polarizing plate (510).

  In FIG. 4B as well, as in FIG. 4A, the backlight unit (80) 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 substrate, an electrode and a color filter are provided on the other transparent substrate, and liquid crystal is sealed between both electrodes. In the first and second polarizing plates provided so as to sandwich the liquid crystal cell (60), the polarizing layer (53, 73) is sandwiched between the transparent base materials (11, 52, 71, 72). It has become.

  Moreover, in the transmissive liquid crystal display of this invention, you may provide another functional member. 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.

  As described above, a transmissive liquid crystal display using the antireflection film of the present invention is manufactured.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to a following example, unless the summary is exceeded.

  A triacetylcellulose film (manufactured by Fuji Film, thickness 60 μm, refractive index 1.49) was prepared as a transparent substrate.

(Coating liquid for forming hard coat layer)
・ Urethane acrylate (trade name: UA306I, manufactured by Kyoeisha Chemical Co., Ltd.) 100 parts by weight ・ Photopolymerization initiator (product name: Irgacure 184, manufactured by Ciba Japan Co., Ltd.), 10 parts by weight It melt | dissolved and the coating liquid for hard-coat layer formation was prepared.

(Formation of hard coat layer)
The hard coat layer forming coating solution was applied to one side of a triacetylcellulose film (film thickness 60 μm) and dried in an oven at 40 ° C. for 60 seconds. After drying, a transparent hard coat layer having a dry film thickness of 5 μm was formed by irradiating with ultraviolet rays at an irradiation dose of 300 mJ / cm ² using an ultraviolet irradiation device (Fusion UV System Japan, light source H bulb).

  Next, a high refractive index layer is formed on the hard coat layer. An example of preparing the coating liquid used at that time is shown below.

(Coating liquid for high refractive index layer)
-Pentaerythritol triacrylate 100 parts by weight-Zirconium oxide dispersion (trade name: NANON5, manufactured by Solar) 500 parts by weight-Photopolymerization initiator (trade name: Irgacure 184, manufactured by Ciba Japan) 10 parts by weight Solid content in methyl ethyl ketone is 10 % To prepare a coating solution for forming a high refractive index layer.

(Formation of high refractive index layer)
As a specific method for forming the high refractive index layer, a coating solution for forming a high refractive index layer was applied on the hard coat layer and dried in an oven at 40 ° C. for 60 seconds. After drying, a transparent high refractive index layer having a dry film thickness of 155 nm was formed by irradiating ultraviolet rays at an irradiation dose of 300 mJ / cm ² using an ultraviolet irradiation device (Fusion UV System Japan, light source H bulb).

  The refractive index of the high refractive index layer at this time was measured with a reflection spectral film thickness meter (FE-3000 manufactured by Otsuka Electronics Co., Ltd.). As a result, the refractive index was 1.62 with respect to the wavelength of 589 nm.

  Next, a low refractive index layer is formed on the high refractive index layer.

(Coating liquid for low refractive index layer Preparation Example 1)
・ Pentaerythritol triacrylate 11 parts by weight ・ Low refractive index silica fine particle dispersion with voids inside (primary particle diameter 60 nm / solid content 20 wt% / methyl ethyl ketone dispersion) 500 parts by weight ・ Photopolymerization initiator (manufactured by Ciba Japan) : Irgacure 184) A coating solution for forming a low refractive index layer was prepared by dissolving in 1 part by weight of methyl ethyl ketone so that the solid content was 10%.

(Coating liquid for low refractive index layer Preparation Example 2)
-100 parts by weight of pentaerythritol triacrylate-500 parts by weight of a low refractive index silica fine particle dispersion having voids inside (primary particle diameter 60 nm / solid content 20 wt% / methyl ethyl ketone dispersion)-Photopolymerization initiator (manufactured by Ciba Japan) : Irgacure 184) A coating solution for forming a low refractive index layer was prepared by dissolving 10 parts by weight of methyl ethyl ketone so that the solid content was 10%.

(Coating liquid for low refractive index layer Preparation Example 3)
・ Pentaerythritol triacrylate 1 part by weight ・ Low refractive index silica fine particle dispersion with voids inside (primary particle diameter 60 nm / solid content 20 wt% / methyl ethyl ketone dispersion) 500 parts by weight ・ Photopolymerization initiator (manufactured by Ciba Japan) : Irgacure 184) A coating solution for forming a low refractive index layer was prepared by dissolving in 0.1 parts by weight of methyl ethyl ketone so that the solid content was 10%.

(Coating liquid for low refractive index layer Preparation Example 4)
・ Pentaerythritol triacrylate 3 parts by weight ・ Low refractive index silica fine particle dispersion having voids in the interior (primary particle diameter 60 nm / solid content 20 wt% / methyl ethyl ketone dispersion) 500 parts by weight ・ Photopolymerization initiator (product name, manufactured by Ciba Japan) : Irgacure 184) A coating solution for forming a low refractive index layer was prepared by dissolving in 0.3 parts by weight of methyl ethyl ketone so that the solid content was 10%.

(Coating liquid for low refractive index layer Preparation Example 5)
・ Pentaerythritol triacrylate 6 parts by weight ・ Low refractive index silica fine particle dispersion having voids in the interior (primary particle diameter 60 nm / solid content 20 wt% / methyl ethyl ketone dispersion) 500 parts by weight ・ Photopolymerization initiator (product name, manufactured by Ciba Japan) : Irgacure 184) A coating solution for forming a low refractive index layer was prepared by dissolving in 0.6 parts by weight of methyl ethyl ketone so that the solid content was 10%.

(Coating liquid for low refractive index layer Preparation Example 6)
・ Pentaerythritol triacrylate 18 parts by weight ・ Low refractive index silica fine particle dispersion having voids inside (primary particle diameter 60 nm / solid content 20 wt% / methyl ethyl ketone dispersion) 500 parts by weight ・ Photopolymerization initiator (Ciba Japan Co., Ltd.) : Irgacure 184) 1.8 parts by weight Methyl ethyl ketone was dissolved to a solid content of 10% to prepare a coating solution for forming a low refractive index layer.

(Coating liquid for low refractive index layer Preparation Example 7)
-43 parts by weight of pentaerythritol triacrylate-500 parts by weight of a low refractive index silica fine particle dispersion having voids inside (primary particle diameter 60 nm / solid content 20 wt% / methyl ethyl ketone dispersion)-Photopolymerization initiator (manufactured by Ciba Japan) : Irgacure 184) A coating solution for forming a low refractive index layer was prepared by dissolving 4.3 parts by weight of methyl ethyl ketone in a solid content of 10%.

  A high refractive index layer is formed on the hard coat layer, and a low refractive index layer is laminated thereon using (Preparation Example 1) to (Preparation Example 7), respectively (Example 1). , (Comparative Example 1), (Comparative Example 2), (Comparative Example 3), (Example 2), (Example 3), and (Comparative Example 4) antireflection films are obtained.

(Formation of a low refractive index layer)
The coating solutions for forming the low refractive index layer (Preparation Example 1) to (Preparation Example 7) were applied onto the high refractive index layer so that the film thickness after drying was 100 nm. The drying process was performed in an oven at 40 ° C. for 60 seconds. After the drying treatment, ultraviolet rays are irradiated at an irradiation dose of 192 mJ / cm ² using an ultraviolet irradiation device (manufactured by Fusion UV System Japan, light source H bulb) to form a low refractive index layer. The antireflection films of Example 1), (Comparative Example 1), (Comparative Example 2), (Comparative Example 3), (Example 2), (Example 3), and (Comparative Example 4) were produced.

  The refractive index of the low refractive index layer at this time was measured with a reflection spectral film thickness meter (manufactured by Otsuka Electronics Co., Ltd., FE-3000). As a result, the antireflection films of (Example 1), (Comparative Example 1), (Comparative Example 2), (Comparative Example 3), (Example 2), (Example 3), and (Comparative Example 4) are sequentially ordered. The refractive index was 1.28, 1.38, 1.24, 1.24, 1.25, 1.29, 1.35 with respect to the wavelength of 589 nm.

  Further, the antireflection films of (Example 1), (Comparative Example 1), (Comparative Example 2), (Comparative Example 3), (Example 2), (Example 3), and (Comparative Example 4) are mapped. The haze was measured using a property measuring instrument (NDH-2000, manufactured by Nippon Denshoku Industries Co., Ltd.). As a result, the antireflection films of (Example 1), (Comparative Example 1), (Comparative Example 2), (Comparative Example 3), (Example 2), (Example 3), and (Comparative Example 4) are sequentially ordered. 0.30%, 0.18%, 0.74%, 0.70%, 0.45%, 0.23%, 0.19%.

  In addition, the antireflection films of (Example 1), (Comparative Example 1), (Comparative Example 2), (Comparative Example 3), (Example 2), (Example 3), and (Comparative Example 4) The surface roughness was measured using an atomic force microscope (manufactured by Bruker AXS). As a result, the antireflection films of (Example 1), (Comparative Example 1), (Comparative Example 2), (Comparative Example 3), (Example 2), (Example 3), and (Comparative Example 4) are sequentially ordered. The arithmetic average roughness (Ra) within 1 μm square was 5.3 nm, 1.7 nm, 10.2 nm, 10.0 nm, 7.1 nm, 3.3 nm, and 2.7 nm.

  The cross section of the obtained antireflection film was observed using a transmission electron microscope. In the antireflection film of (Example 1), the area occupation ratio of the hollow silica in the low refractive index layer was 86%. In the antireflection film of (Comparative Example 1), the area occupancy of the hollow silica in the low refractive index layer was 45%. In the antireflection film of (Comparative Example 2), the area occupancy of the hollow silica in the low refractive index layer was 95%. Similarly, (Comparative Example 3), (Example 2), (Example 3), (Comparative Example 4) The area occupancy was 95%, 93%, 80%, and 65%.

  However, the antireflective film obtained in (Comparative Example 2) did not have sufficient film strength, and it was confirmed that the low refractive index layer peeled off during winding. Further, after 24 hours, many white turbidities were formed on the surface layer and the function as a transparent film was not satisfied.

  In the antireflection film obtained in the examples, an antireflection film having a low refractive index layer having a refractive index of less than 1.30 could be provided.

  In addition to optical films such as windows and displays, the antireflection film of the present invention includes a diffusion film, a prism sheet, a brightness enhancement film, a touch panel, a liquid crystal cell, a member for compensating optical characteristics of a polarizing plate, a lens, a prism element, It can be applied to all members that should prevent reflection, such as light-emitting diodes, photodiodes, CCDs, and lighting equipment.

DESCRIPTION OF SYMBOLS 1 Antireflection film 11, 51, 52 Transparent base material 12 Hard coat layer 14 High refractive index layer 15 Low refractive index layer 16 Binder resin 17 Fine particle 21 Coating process 22 Heating / drying process 23 Curing process 31 Unwinding part 32 Winding up Part 50 First polarizing plate 53 First polarizing layer 60 Liquid crystal cell 70 Second polarizing plate 73 Second polarizing layer 80 Backlight unit 500, 510 Antireflection polarizing plate

Claims (8)

An antireflection film having a low refractive index layer on at least a transparent substrate,
The low refractive index layer is composed of a binder resin and fine particles,
The arithmetic average roughness (Ra) of the surface of the low refractive index layer is 3 nm or more and 8 nm or less,
The average primary particle diameter of the fine particles is 20 nm to 300 nm,
An antireflection film, wherein an area occupation ratio of the fine particles to the low refractive index layer is higher than an area occupation ratio of the binder resin to the low refractive index layer.   2. The antireflection film according to claim 1, wherein the haze is from 0.1% to 1.0%.   The antireflection film according to claim 1, wherein the fine particles are silica particles.   The antireflection film according to any one of claims 1 to 3, wherein the fine particles are hollow silica particles.   5. The antireflection film according to claim 1, comprising at least a hard coat layer, a high refractive index layer, and the low refractive index layer in this order on the transparent substrate.   An antireflective polarizing plate using the antireflective film according to any one of claims 1 to 5, wherein the transparent substrate has a surface opposite to the surface provided with the low refractive index layer. An antireflective polarizing plate having 2 transparent base materials and a first polarizing layer in this order.   A transmissive liquid crystal display comprising the antireflective polarizing plate according to claim 6, a liquid crystal cell, a second polarizing plate, and a backlight unit in this order from the viewer side. A method for producing the antireflection film according to any one of claims 1 to 5 by a wet method,
A coating film forming step of applying a low refractive index layer-forming coating liquid containing a binder resin and fine particles on a transparent substrate, and forming a coating film,
A drying step of drying the coating film;
Curing by irradiating with ionizing radiation after drying the coating film, and forming a low refractive index layer with a thickness of 50 nm or more and 150 nm or less,
The manufacturing method of the antireflection film characterized by having.

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