JP5365083B2 - Antireflection film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an antireflection film which has a superior antistatic function and a superior antireflection function and reduces hue of reflected light and suppresses the occurrence of color unevenness. <P>SOLUTION: The antireflection film has a hard coat layer, an antistatic layer including a binder matrix and electroconductive particles and a low refractive index layer including the binder matrix and low refraction particles on at least one surface of a transparent base material in order from a transparent base material side. Visual average reflectivity at an antireflection film surface of a low refractive index layer side is in a range of 0.5 to 1.5%. A spectral reflectivity curve in a wavelength range of 400 to 700 nm at the antireflection film surface of the low refractive index layer side has no maximal value but has one minimum value. Difference between the maximal value and the minimum value of spectral reflectivity in the wavelength range of 400 to 700 nm at the antireflection film surface of the low refractive index layer side is in a range of 0.2 to 0.9%. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to an antireflection film provided for the purpose of preventing external light from being reflected on the surface of a window or 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 surface of a liquid crystal display (LCD).

  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. For this reason, it is essential to provide an antireflection function on the display surface or the like, and there is a demand for higher performance of the antireflection function and a combination of functions other than the antireflection function.

  In general, the antireflection function is 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. 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, when these antireflection layers are provided on a film transparent substrate, the surface thereof is relatively flexible, so in order to impart surface hardness, a polymer of an acrylic polyfunctional compound is generally used. A method of providing a hard coat layer to be formed and forming an antireflection layer thereon is used. This hard coat layer has high surface hardness, gloss, transparency, and scratch resistance due to the characteristics of acrylic resin, but it is easily charged due to its high insulation properties, and dust on the product surface provided with the hard coat layer. There are problems such as contamination due to adhesion and troubles caused by charging in the display manufacturing process.

  Therefore, in order to impart an antistatic function, there are a method of adding a conductive agent to the hard coat layer, and a method of providing an antistatic layer between the base material and the hard coat layer, or between the hard coat layer and the antireflection layer. Has been made.

JP-A-2005-202389 JP 2005-199707 A JP 2006-16447 A

  In the method of adding a conductive substance to the hard coat layer, it is necessary to add a large amount of a conductive substance in order to develop good conductivity. As a result, the material cost is improved and the strength of the hard coat layer is reduced. Such a problem may occur. On the other hand, in the method of newly providing an antistatic layer, a generally high antistatic layer has to be laminated between the layers, resulting in occurrence of color and color unevenness. In particular, when an antistatic layer and a low refractive index layer are formed by a wet film forming method, the antireflection film reflects the variation in the thickness of the antistatic layer and the low refractive index layer to be formed. Color unevenness is confirmed. In the present invention, an antireflection film comprising a hard coat layer, an antistatic layer, and a low refractive index layer in this order on a transparent substrate, has an excellent antistatic function, antireflection function, and reflected light. It is an object of the present invention to provide an antireflection film that reduces the color tone and suppresses color unevenness.

In order to solve the above-mentioned problem, the invention according to claim 1 includes, on at least one surface of a transparent base material, in order from the transparent base material side, a hard coat layer, a binder matrix and an antistatic layer comprising conductive particles, a binder An antireflective film comprising a low refractive index layer comprising a matrix and low refractive particles,
The transparent substrate has a thickness of 80 μm and a refractive index of 1.49, the hard coat layer has a thickness of 5 μm and a refractive index of 1.52, and the antistatic layer has an optical thickness of 250 μm and a refractive index. The antireflective film was characterized in that the refractive index was 1.53, the low refractive index layer had an optical film thickness of 125 μm, and a refractive index of 1.33 or 1.37 .

According to a second aspect of the present invention, there is provided the antireflection film according to the first aspect, wherein the conductive particles used in the antistatic layer are electron conductive type conductive particles.

As the invention according to claim 3, the binder matrix in the binder matrix and the low-refractive index layer in the antistatic layer is reflected according to any one of claims 1 to 2, characterized in that a silica matrix It was a prevention film.

Moreover, as invention which concerns on Claim 4 , as for the surface of the transparent base film opposite to the side in which the low refractive index layer of the antireflection film in any one of Claims 1 thru | or 3 is provided, a polarizing layer, It was set as the polarizing plate provided with a transparent base film.

Moreover, as invention which concerns on Claim 5 , as for the surface of the transparent base film opposite to the side in which the low-refractive-index layer of the antireflection film in any one of Claims 1 thru | or 4 is provided, a polarizing layer, A transmissive liquid crystal display comprising a polarizing plate, a liquid crystal cell, a polarizing plate, and a backlight unit provided with a transparent substrate film in this order was obtained.

  By using the antireflection film having the above-described configuration, it was possible to obtain an antireflection film having an excellent antistatic function and antireflection function, reducing the color of reflected light, and suppressing occurrence of color unevenness. .

  The antireflection film of the present invention will be described below.

  FIG. 1 shows a schematic cross-sectional view of the antireflection film of the present invention. The antireflection film (1) of the present invention shown in FIG. 1 comprises a hard coat layer (12), an antistatic layer (13), and a low refractive index layer (14) in this order on a transparent substrate (11). The antistatic layer (13) includes conductive particles (13A) and a binder matrix (13B), and the low refractive index layer (14) includes low refractive index particles (14A) and a binder matrix (14B).

  The antireflection film of the present invention exhibits an antireflection function due to optical interference between the low refractive index layer (14) and the antistatic layer (13). That is, the antistatic layer (13) functions as a high refractive index layer.

  In forming the antistatic layer (13) in the antireflection film of the present invention, a coating liquid containing conductive particles and a binder matrix forming material is used, and the coating liquid is applied onto the hard coat layer by a wet film forming method. It is formed by doing. Similarly, in forming the low refractive index layer (14), a coating liquid containing low refractive index particles and a binder matrix forming material is used, and the coating liquid is applied on the antistatic layer by a wet film forming method. It is formed.

  In the antireflection film of the present invention, the visual average reflectance on the surface of the antireflection film on the low refractive index layer side is in the range of 0.5% to 1.5%, and the low The spectral reflectance curve in the wavelength range of 400 nm to 700 nm on the surface of the antireflective film on the refractive index layer side has one minimum value instead of having a maximum value, and the surface of the antireflective film on the low refractive index layer side The difference between the maximum value and the minimum value of the spectral reflectance in the wavelength range of 400 nm to 700 nm is in the range of 0.2% to 0.9%.

FIG. 2 shows an explanatory view of the spectral reflectance curve (model) of the antireflection film of the present invention.
The spectral reflectance curve on the surface of the antireflective film on the low refractive index layer side in the present invention is obtained by applying a matte black paint on the surface of the transparent substrate on which the hard coat layer, antistatic layer, and low refractive index layer are not provided. In addition, it is measured by a spectrophotometer. The spectral reflectance curve of the antireflection film of the present invention is obtained under the condition of a 2-degree visual field using a C light source as a light source, with the incident angle set to 5 degrees from the direction perpendicular to the antireflection film surface. The luminous average 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.

  The antireflection film of the present invention is characterized in that the average visual reflectance of the antireflection film on the low refractive index layer side is from 0.5% to 1.3%. In the case where the luminous average reflectance exceeds 1.3%, an antireflection film having an antireflection function sufficient to be provided on the display surface cannot be obtained. On the other hand, when the luminous average reflectance is less than 0.5%, the difference between the maximum value and the minimum value of the spectral reflectance in the wavelength range of 400 nm to 700 nm may be 0.9% or less. It becomes difficult.

  In the antireflection film of the present invention, as shown in FIG. 2, the spectral reflectance curve in the wavelength range of 400 nm to 700 nm on the antireflective film surface on the low refractive index layer side does not have a maximum value but one minimum value. It is characterized by having. Further, the antireflection film of the present invention has a difference (A−B) between the maximum value (A) and the minimum value (B) of the spectral reflectance in the wavelength range of 400 nm to 700 nm on the antireflective film surface on the low refractive index layer side. ) Is in the range of 0.2% to 0.9%. The spectral reflectance curve of the antireflection film of the present invention is a U-shaped spectral reflectance curve between 400 nm and 700 nm, which gradually decreases as the wavelength increases and gradually increases with the minimum value as a boundary. .

  The spectral reflectance curve in the wavelength range of 400 nm to 700 nm of the antireflection film of the present invention is U-shaped and is a very flat curve that gradually changes between the wavelength range of 400 nm and 700 nm. To do. By making the spectral reflectance curve a U-shaped curve that changes very gently, not only the reflected hue is nearly colorless, but also an antireflection film having no color unevenness can be obtained.

  When forming an antistatic layer and a low refractive index layer by a wet film-forming method using a coating solution, compare with the case of forming an antistatic layer and a low refractive index layer by a dry film formation that requires a vacuum device. Thus, the manufacturing cost can be greatly reduced. When the antistatic layer and the low refractive index layer are formed by a wet film forming method, it is possible to provide an antireflection film at a low cost.

  However, compared with the case of forming an antistatic layer and a low refractive index layer by a dry film forming method such as an evaporation method or a sputtering method, the antistatic layer and the antireflection layer are formed by a wet film forming method using a coating liquid. In some cases, the thickness of the antistatic layer and antireflection layer to be formed tends to fluctuate in a small amount in the plane. Since the antireflection film exhibits an antireflection function due to optical interference between the low refractive index layer and the antistatic layer, when the film thickness of the antistatic layer or the antireflection layer varies slightly in the plane, the antireflection film It is confirmed as uneven color in the surface.

  In the present invention, the antireflective film has a U-shaped spectral reflectance curve that changes very slowly, so that the formed antireflective layer and the antistatic layer have a small variation in film thickness. Color unevenness due to can be suppressed. That is, the antireflection film of the present invention includes an antistatic layer formed by a wet film formation method, an antireflection film that is less likely to be recognized as color unevenness even if minute film thickness unevenness occurs in the surface of the antireflection layer, and can do. When the amount of change in reflectance with respect to the wavelength of the spectral reflectance curve is large, the color tends to change when the spectral reflectance curve changes due to variations in the film thickness of the antistatic layer and the low refractive index layer. It becomes easy to be recognized as color unevenness.

  When the difference (A−B) between the maximum value (A) and the minimum value (B) of the spectral reflectance in the wavelength range of 400 nm to 700 nm on the antireflective film surface on the low refractive index layer side exceeds 0.9% In that case, the spectral reflectance curve is accompanied by a steep change. Therefore, not only the reflection hue becomes large, but also color unevenness due to film thickness variation of the antistatic layer and antireflection layer is confirmed.

  Further, the difference (AB) between the maximum value (A) and the minimum value (B) of the spectral reflectance in the wavelength range of 400 nm to 700 nm on the antireflective film surface on the low refractive index layer side is preferably smaller. An antireflection film with a difference (AB) between the maximum value (A) and the minimum value (B) of the spectral reflectance of less than 0.5% is realized by optical interference between the low refractive index layer and the antistatic layer. It is difficult to do.

  In the present invention, the spectral reflectance curve has one minimum value between 400 nm and 700 nm, and the maximum spectral reflectance in the wavelength range of 400 nm to 700 nm on the antireflective film surface on the low refractive index layer side. By making the difference (A−B) between the value (A) and the minimum value (B) 0.9% or less, the curve changes gently between the wavelength range of 400 nm and 700 nm, and the curve is very flat. Can do.

  In the antireflection film of the present invention, the spectral reflectance curve is almost flat in the vicinity of a wavelength of 550 nm where the relative luminous efficiency is high, so that not only the reflection hue is nearly colorless but also an antireflection film having no color unevenness. can do. In order to obtain an antireflection film having a colorless reflection hue and no color unevenness, it is required that a spectral reflectance curve near a wavelength of 550 nm with high specific visibility is as flat as possible.

  Further, in the antireflection film of the present invention, the amount of change between the falling portion on the low wavelength side (near 400 nm to 450 nm) and the rising portion on the high wavelength side (near 600 to 700 nm) of the spectral reflectance curve is reduced. In addition, the reflection hue is not nearly colorless, and an antireflection film having no color unevenness can be obtained. In particular, the amount of change in the falling portion on the low wavelength side (wavelength side in the vicinity of 400 nm to 450 nm can be reduced, and not only the reflection hue is nearly colorless but also an antireflection film having no blue color unevenness. it can.

  In the antireflection film, the lower the luminous reflectance, the higher the antireflection film can be. However, when obtaining high antireflection performance, it is difficult to reduce the color of the reflected light and to suppress the occurrence of color unevenness. That is, in the present invention, the luminous reflectance is 0.5% to 1.3%, and the difference between the maximum value and the minimum value of the spectral reflectance is in the range of 0.2% to 0.9%. As a result, the color of the reflected light was reduced, and furthermore, the occurrence of color unevenness was successfully suppressed. In other words, by gradually changing the spectral reflectance curve in the wavelength range from 400 nm to 700 nm on the low refractive index layer side to make a flat U-shaped curve, the color of the reflected light is reduced, and further, the wet- It was possible to obtain an antireflection film in which color unevenness caused by minute film thickness variations of the low refractive index layer and the antistatic layer formed by the film method is difficult to be confirmed.

  Further, in the antireflection film of the present invention, the difference between the refractive index of the hard coat layer and the refractive index of the transparent substrate is in the range of 0.05 or less of the refractive index of the transparent substrate, and The refractive index difference between the refractive index of the antistatic layer and the refractive index of the hard coat layer is in the range of 0.01 to 0.05, and the optical film thickness of the antistatic layer is 230 nm to 270 nm. In addition, the optical film thickness of the low refractive index layer is preferably 115 nm or more and 135 nm or less.

  In the present invention, the refractive index difference between the transparent substrate and the hard coat layer, and the refractive index difference between the hard coat layer and the antistatic layer are within the above ranges, and the optical film thickness of the antistatic layer and the low refractive index layer By making the optical film thickness within the above range, the spectral reflectance curve can be easily made into a U-shaped and very gentle curve, the reflection hue is almost colorless, and an antireflection film without color unevenness can be obtained. .

  In the present invention, the refractive indexes of the hard coat layer and the antistatic layer can be determined by a direct measurement method such as a Becke line method or an optical thin film simulation method using a spectrophotometer or a spectroscopic ellipsometer.

  In the antireflection film of the present invention, the difference in refractive index between the transparent substrate and the hard coat layer is preferably within 0.05. When the refractive index difference between the refractive index of the hard coat layer and the refractive index of the transparent substrate exceeds 0.05, interference fringes are generated due to interference of light between layers.

  In the antireflection film of the present invention, the difference in refractive index between the hard coat layer and the antistatic layer is preferably from 0.01 to 0.05. When the refractive index difference between the hard coat layer and the antistatic layer exceeds 0.05, the difference between the maximum value and the minimum value of the spectral reflectance is 0.2% or more due to interference caused by light interference between layers. It becomes difficult to make it within the range of .9% or less. On the other hand, when the difference in refractive index between the hard coat layer and the antistatic layer is less than 0.01, the refractive index of the hard coat layer and the antistatic layer is almost the same. As a result, it becomes difficult to make the light reflectance curve a U-shaped and very gentle curve.

  In the antireflection film of the present invention, the optical film thickness of the antistatic layer is preferably 230 nm or more and 270 nm or less, and the optical film thickness of the low refractive index layer is preferably 115 nm or more and 135 nm or less. .

  The antireflection film of the present invention is designed so that the optical film thickness of the antistatic layer is around λ / 2 and the low refractive index layer is around λ / 4 when λ = 500 nm. By setting the antistatic layer near λ / 2 and the low refractive index layer near λ / 4 with λ = 500 nm, the resulting spectral reflectance curve has one minimum value without transferring the maximum value, and the wavelength is It is a U-shaped curve that gradually decreases as it increases and gradually increases with the minimum value as a boundary, and can be a very flat curve.

  As shown in FIG. 2, the spectral reflectance curve of the antireflection film of the present invention shows a tendency that the rising curve in the short wavelength direction is steeper than the rising curve in the long wavelength direction on the basis of the minimum value. At this time, the steep rising curve in the short wavelength direction when the minimum value of the spectral reflectance curve is used as a reference causes the occurrence of color unevenness when the film thickness unevenness of the antistatic layer or antireflection layer occurs. . In the present invention, by setting the minimum value of the spectral reflectance curve to around 500 nm, the reflection hue is small, and the difference (AB) between the maximum value (A) and the minimum value (B) of the spectral reflectance is small. Of 0.9% or less, and the occurrence of color unevenness due to a steep rising curve in the short wavelength direction could be suppressed.

  For example, in the case where the film thickness of the low refractive index layer is λ / 4 and the film thickness of the antistatic layer is λ / 2 with reference to light having a wavelength (λ) of 550 nm with high specific visibility, the short wavelength direction Ascending curve increases, and the reflectance at a wavelength of 400 nm increases. Therefore, it is difficult to make the difference between the maximum and minimum spectral reflectances within 0.9%, and blue color unevenness occurs due to minute film thickness variations of the low refractive index layer and antistatic layer. It becomes easy.

  In the antireflection film of the present invention, the reflection hue in the L * a * b * chromaticity system on the surface of the antireflection film on the low refractive index layer side is 0 ≦ a * ≦ 3 and −3 ≦ b * ≦ 3. It is preferable that By making the reflection hue in the L * a * b * chromaticity system on the antireflective film surface on the low refractive index layer side within the above range, it is possible to make an antireflective film having no color, It can be used suitably.

  The reflection hue is closer to colorless as a * and b * are closer to zero. However, −3 ≦ a * <0 is a green region with high specific visibility, and the color tends to be easily recognized by the observer. Therefore, in the antireflection film of the present invention, it is preferable that 0 ≦ a * ≦ 3 and −3 ≦ b * ≦ 3.

  The reflection hue of the antireflection film of the present invention is obtained by applying a matte black paint on the surface of the transparent substrate on which the hard coat layer, the antistatic layer, and the low refractive index layer are not provided. Measured by The incident angle is set to 5 degrees from the direction perpendicular to the antireflection film, and is obtained under the condition of a 2-degree visual field using a C light source as a light source.

  In the antireflection film of the present invention, it is preferable that the conductive particles used in the antistatic layer are electronic conductive particles. The conductive particles used for the antistatic layer are classified into proton conductive type conductive particles and electron conductive type conductive particles. At this time, when proton conductive type conductive particles are used, the desired antistatic performance may not be obtained when the antireflection film is used under low humidity. On the other hand, in the case of using electronic conductive type conductive particles, good antistatic performance can be stably exhibited even under low humidity.

In the antireflection film of the present invention, the surface resistance value of the antireflective film surface on the low refractive index layer side is preferably 1.0 × 10 ¹⁰ (Ω / cm ² ) or less. By setting the surface resistance value of the antireflective film surface on the low refractive index layer side to 1.0 × 10 ¹⁰ (Ω / cm ² ) or less, an antireflective film having excellent antistatic properties can be obtained. When the surface resistance value of the surface of the antireflection film exceeds 1.0 × 10 ¹⁰ (Ω / cm ² ), the antireflection film is provided on the display surface in order not to have sufficient antistatic properties. It will not be possible to prevent adhesion of dust and the like.

Moreover, it is preferable that the surface resistance value of the surface of the antireflective film on the low refractive index layer side is 1.0 × 10 ⁶ (Ω / cm ² ) or more. When the surface resistance value of the antireflective film surface on the low refractive index layer side is less than 1.0 × 10 ⁶ (Ω / cm ² ), it is necessary to add a large amount of conductive particles in the binder matrix, which is uneconomical. In other words, the strength and optical characteristics cannot be adjusted within the present invention.

  In the antireflection film of the present invention, the binder matrix in the antistatic layer and the binder matrix in the low refractive index layer are preferably a silica matrix. In order to use the binder matrix as a silica matrix, silicon alkoxide is used as a binder matrix forming material, and a hydrolyzate of the silicon alkoxide is applied and dried. By using a silica matrix as the binder matrix, an antireflection film having high transparency and less tint can be obtained. Further, by using both the binder matrix in the antistatic layer and the binder matrix in the low refractive index layer as a silica matrix, the adhesion between the antistatic layer and the low refractive index layer can be improved.

  Next, a polarizing plate using the antireflection film of the present invention is shown. FIG. 3 shows a schematic cross-sectional view of a polarizing plate using the antireflection film of the present invention. The polarizing plate (2) has a structure in which a polarizing layer is sandwiched between two transparent substrates. In the polarizing plate (2) of the present invention, the polarizing layer (23) is provided on the opposite surface of the transparent base material (11) of the antireflection film (1) where the low refractive index layer (14) is provided. The transparent base material (22) is provided in order. That is, the transparent base material (11) of the antireflection film (1) has a structure also serving as a transparent base material for sandwiching the polarizing layer.

Next, a transmissive liquid crystal display using the antireflection film of the present invention will be described.
FIG. 4 shows a transmissive liquid crystal display provided with the antireflection film of the present invention. The transmissive liquid crystal display of FIG. 4 includes a backlight unit (5), a polarizing plate (4), a liquid crystal cell (3), and a polarizing plate (2) including an antireflection film (1) in this order. At this time, the antireflection film side becomes the observation side, that is, the display surface.

  The backlight unit includes a light source and a light diffusing 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. The two polarizing plates are provided so as to sandwich the liquid crystal cell.

  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.

  Below, the manufacturing method of the antireflection film of this invention is 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. 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. Among them, triacetyl cellulose can be suitably used for a liquid crystal display because it has a small birefringence and good transparency.

  The thickness of the transparent substrate is preferably in the range of 25 μm to 200 μm, and more preferably in the range of 40 μm to 80 μm.

  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.

  Next, a method for forming a hard coat layer will be described. The hard coat layer is formed by applying a coating liquid containing an electron radiation curable material on a transparent substrate, forming a coating on the transparent substrate, and drying the coating as necessary. A hard coat layer can be formed by carrying out a curing reaction of the ionizing radiation curable material by irradiating with ionizing radiation such as ultraviolet rays and electron beams. As a coating method, 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.

  Examples of the ionizing radiation curable material for forming the hard coat layer include three or more (meth) acryloyl groups such as acrylic esters, acrylamides, methacrylic esters, and methacrylamides, preferably 4 to Examples include 20 polyfunctional acrylates. The polyfunctional acrylate may be a monomer or an oligomer. Examples of the polyfunctional acrylate include trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, and the like.

  Among the polyfunctional acrylates, a polyfunctional urethane acrylate can be suitably used because the desired molecular weight and molecular structure can be designed and the physical properties of the formed hard coat layer can be easily balanced. . The urethane acrylate is obtained by reacting a polyhydric alcohol, a polyvalent isocyanate, and a hydroxyl group-containing acrylate. Specifically, Kyoeisha Chemical Co., Ltd., UA-306H, UA-306T, UA-306l, etc., Nippon Synthetic Chemical Co., Ltd., UV-1700B, UV-6300B, UV-7600B, UV-7605B, UV-7640B, UV -7650B, etc., manufactured by Shin-Nakamura Chemical Co., Ltd., U-4HA, U-6HA, UA-100H, U-6LPA, U-15HA, UA-32P, U-324A, etc., manufactured by Daicel UCB, Ebecryl-1290 -1290K, Ebecryl-5129, etc., manufactured by Negami Kogyo Co., Ltd., UN-3220HA, UN-3220HB, UN-3220HC, UN-3220HS, etc. can be mentioned, but not limited thereto.

  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. .

  When the hard coat layer forming coating solution is cured by ultraviolet rays, a photopolymerization initiator is added to the hard coat layer forming coating solution. Any photopolymerization initiator may be used as long as it generates radicals when irradiated with ultraviolet rays. For example, acetophenones, benzoins, benzophenones, phosphine oxides, ketals, anthraquinones, thioxanthones are used. Can do. The addition amount of the photopolymerization initiator is 0.1 to 10 parts by weight, preferably 1 to 7 parts by weight, more preferably 1 to 5 parts by weight with respect to 100 parts by weight of the ionizing radiation curable material. Parts by weight.

  Furthermore, a solvent and various additives can be added to the coating liquid for forming a hard coat layer as necessary. 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 Esters such as acetic acid n- pentyl, and γ- butyrolactone, furthermore, methyl cellosolve, cellosolve, butyl cellosolve, is suitably selected from such cellosolves such as cellosolve acetate in consideration of the coating proper and the like. In addition, a surface adjusting agent, a refractive index adjusting agent, an adhesion improver, a curing agent, and the like can be added to the coating liquid as additives.

  Especially, in the solvent of the coating liquid for hard-coat formation, it is preferable to contain the solvent which melt | dissolves a transparent base material. Adhesion between the hard coat layer formed by including the solvent for dissolving the transparent substrate and the transparent substrate can be improved.

  In addition, by including particles with an average particle size of 0.5 μm or more and 10 μm or less in the hard coat layer forming coating solution, irregularities are formed on the surface of the hard coat layer, and the resulting antireflection layer is imparted with antiglare properties. can do. At this time, the particles added to the hard coat layer preferably have translucency. Specifically, the particles include acrylic particles, PMMA particles, acrylic styrene particles, PMMA styrene particles, polystyrene particles, polycarbonate particles, melamine particles, epoxy particles, polyurethane particles, nylon particles, polyethylene particles, polypropylene particles, silicone particles, Polytetrafluoroethylene particles, polyvinylidene fluoride particles, polyvinyl chloride particles, polyvinylidene chloride particles, glass particles, silica particles, and the like can be used. A plurality of kinds of particles can be used.

  Further, for the purpose of improving the surface hardness of the hard coat layer to be formed, particles having an average particle size of 100 nm or less may be added to the hard coat layer forming coating solution.

  Moreover, you may add another additive to the coating liquid for hard-coat layer formation. Examples of the additive include, but are not limited to, an antifoaming agent, a leveling agent, an antioxidant, an ultraviolet absorber, a light stabilizer, and a polymerization inhibitor.

  In addition, a thermoplastic resin may be added to the coating liquid for the purpose of preventing curling of the antireflection film provided with the hard coat layer after formation. Thus, the hard coat layer is formed.

  Before forming the antistatic layer on the hard coat layer, surface treatment such as acid treatment, alkali treatment, corona treatment method, atmospheric pressure glow discharge plasma method is performed before forming the antistatic layer. Also good. By performing these surface treatments, the adhesion between the hard coat layer and the lower refractive index layer lower layer or the high refractive index layer can be further improved.

  When forming an antistatic layer using a metal alkoxide such as silicon alkoxide as a binder matrix forming material on the hard coat layer, it is preferable to perform an alkali treatment before forming the antistatic layer. By performing the alkali treatment, the adhesion between the hard coat layer and the antistatic layer can be improved, and the scratch resistance of the antireflection film can be further improved.

  In the antistatic layer of this invention, it can form by apply | coating the coating liquid containing electroconductive highly refractive particle and binder matrix formation material, and forming a coating film on a transparent base material. At this time, as a coating method, 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.

  Examples of conductive particles include indium oxide, tin oxide, indium oxide-tin oxide (ITO), zinc oxide, zinc oxide-aluminum oxide (AZO), zinc oxide-gallium oxide (GZO), indium oxide-cerium oxide, and antimony oxide. Further, conductive metal oxide particles such as antimony oxide-tin oxide (ATO) and tungsten oxide can be used.

  Among them, inductive conductivity such as indium oxide, tin oxide, indium oxide-tin oxide (ITO), zinc oxide, zinc oxide-aluminum oxide (AZO), zinc oxide-gallium oxide (GZO), indium oxide-cerium oxide. Particles can be suitably used.

  The conductive particles used in the antistatic layer of the present invention preferably have a particle size of 1 nm to 100 nm. When the particle diameter exceeds 100 nm, light is remarkably reflected by Rayleigh scattering, and the conductive layer tends to be white and the transparency of the antireflection film tends to decrease. On the other hand, when the particle size is less than 1 nm, there may be problems such as a decrease in conductivity and non-uniformity of particles in the conductive layer due to particle aggregation.

As the binder matrix forming material, a hydrolyzate of silicon alkoxide can be used. Furthermore, the hydrolysis of the silicon alkoxide represented by the general formula (1) R _x Si (OR ′) _4-x (wherein R represents an alkyl group and x is an integer satisfying 0 ≦ x ≦ 3). A decomposition product can be used.

  Examples of the silicon alkoxide represented by the general formula (1) include tetramethoxysilane, tetraethoxysilane, tetra-iso-propoxysilane, tetra-n-propoxysilane, tetra-n-butoxysilane, and tetra-sec-butoxy. Silane, tetra-tert-butoxysilane, tetrapentaethoxysilane, tetrapenta-iso-propoxysilane, tetrapenta-n-proxysilane, tetrapenta-n-butoxysilane, tetrapenta-sec-butoxysilane, tetrapenta-tert-butoxysilane, methyl Trimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, methyltributoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, dimethylethoxysilane, dimethylmethan Kishishiran, dimethyl propoxysilane, dimethyl-butoxy silane, can be used methyl dimethoxysilane, methyl diethoxy silane, hexyl trimethoxy silane. The hydrolyzate of silicon alkoxide may be obtained by using a metal alkoxide represented by the general formula (I) as a raw material, and is obtained, for example, by hydrolysis with hydrochloric acid.

As a hydrolyzate of silicon alkoxide, general formula (1) R _x Si (OR ′) _4-x (wherein R represents an alkyl group, x is an integer satisfying 0 ≦ x ≦ 3) Furthermore, in general formula (2) R ″ _y Si (OR ′) _4-y (where R ″ represents a reactive functional group, and y is an integer satisfying 1 ≦ y ≦ 3). The indicated silicon alkoxide hydrolyzate can be added. At this time, an epoxy group or a glycidoxy group can be preferably used as the reactive functional group used for R ″. The ratio of the silicon alkoxide represented by the general formula (2) is preferably 0.5 mol% or more and 30 mol% or less, and more preferably 4 mol% or more and 12 mol% or less with respect to the total silicon alkoxide. Weather resistance can be improved by using the silicon alkoxide represented by the general formula (2) containing a reactive functional group.

  An ionizing radiation curable material can also be used as the binder matrix forming material. A polyfunctional acrylate such as a polyfunctional urethane acrylate can be used as the ionizing radiation curable material. 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. .

  When a hydrolyzate of silicon alkoxide is used as the binder matrix forming material, a coating liquid containing a hydrolyzate of silicon alkoxide and conductive particles is applied to form a coating film on a transparent substrate, and the coating film By drying and heating, a dehydration condensation reaction of silicon alkoxide can be performed to form a binder matrix, and a high refractive index layer can be formed. Further, when an ionizing radiation curable material is used as a binder matrix forming material, a coating liquid containing an ionizing radiation curable material and conductive particles is applied to form a coating film on a transparent substrate. On the other hand, drying can be performed as necessary, and then a binder matrix can be formed by carrying out a curing reaction of the ionizing radiation curable material by irradiating with ionizing radiation such as ultraviolet rays and electron beams. Can be formed.

In addition, a solvent and various additives can be added to a coating liquid as needed. 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 , Esters such as n-pentyl acetate and γ-ptyrolactone, cellosolves such as methyl cellosolve, cellosolve, butyl cellosolve, cellosolve acetate, alcohols such as methanol, ethanol, isopropyl alcohol, water, etc. It is appropriately selected in consideration of appropriateness and the like. Moreover, a surface adjusting agent, an antistatic agent, an antifouling agent, a water repellent, a refractive index adjusting agent, an adhesion improver, a curing agent, and the like can be added to the coating liquid as additives.

  The method for forming the low refractive index layer of the present invention will be described. The low refractive index layer of the present invention can be formed by a wet film forming method, and can be formed by applying a coating liquid containing low refractive index particles and a binder matrix forming material. At this time, as a coating method, 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 low-refractive particles are made of a low-refractive material such as LiF, MgF, 3NaF.AlF or AlF (all having a refractive index of 1.4), or Na ₃ AlF ₆ (cryolite, having a refractive index of 1.33). Low refractive index particles 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, low refractive index silica particles having voids inside can be used.

  The low refractive index particles used in the low refractive index layer of the present invention preferably have a particle size of 1 nm to 100 nm. 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 non-uniformity of particles in the low refractive index layer due to aggregation of particles occur.

As the binder matrix forming material, a hydrolyzate of silicon alkoxide can be used. Furthermore, hydrolysis of the silicon alkoxide represented by the general formula (1) R _x Si (OR) _4-x (wherein R represents an alkyl group and x is an integer satisfying 0 ≦ x ≦ 3). Can be used.

  Examples of the silicon alkoxide represented by the general formula (1) include tetramethoxysilane, tetraethoxysilane, tetra-iso-propoxysilane, tetra-n-propoxysilane, tetra-n-butoxysilane, and tetra-sec-butoxy. Silane, tetra-tert-butoxysilane, tetrapentaethoxysilane, tetrapenta-iso-propoxysilane, tetrapenta-n-proxysilane, tetrapenta-n-butoxysilane, tetrapenta-sec-butoxysilane, tetrapenta-tert-butoxysilane, methyl Trimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, methyltributoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, dimethylethoxysilane, dimethylmethan Kishishiran, dimethyl propoxysilane, dimethyl-butoxy silane, can be used methyl dimethoxysilane, methyl diethoxy silane, hexyl trimethoxy silane. The hydrolyzate of silicon alkoxide may be obtained by using a metal alkoxide represented by the general formula (I) as a raw material, and is obtained, for example, by hydrolysis with hydrochloric acid.

Furthermore, as the binder matrix forming material of the low refractive index layer, the silicon alkoxide represented by the general formula (1) may be replaced with the general formula (2) R ′ _z Si (OR) _4-z (where R ′ Is a non-reactive functional group having an alkyl group, a fluoroalkyl group or a fluoroalkylene oxide group, and z is an integer satisfying 1 ≦ z ≦ 3). Antifouling property can be imparted to the surface of the low refractive index layer of the antireflection film, and the refractive index of the low refractive index layer can be further reduced.

  Examples of the silicon alkoxide represented by the general formula (2) include octadecyltrimethoxysilane, 1H, 1H, 2H, 2H-perfluorooctyltrimethoxysilane, and the like.

  An ionizing radiation curable material can also be used as the binder matrix forming material. A polyfunctional acrylate such as a polyfunctional urethane acrylate can be used as the ionizing radiation curable material. 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. .

  When a hydrolyzate of silicon alkoxide is used as the binder matrix forming material, a coating liquid containing a hydrolyzate of silicon alkoxide and low refractive index particles is applied to form a coating film on a transparent substrate, and the coating is performed. The film can be dried and heated, and a dehydration condensation reaction of silicon alkoxide can be performed to form a binder matrix, thereby forming a low refractive index layer lower layer. When an ionizing radiation curable material is used as the binder matrix forming material, a coating liquid containing the ionizing radiation curable material and low refractive index particles is applied to form a coating film on the transparent substrate, and the coating is performed. The film can be dried as necessary, and then irradiated with ionizing radiation such as ultraviolet rays and electron beams to form a binder matrix by curing the ionizing radiation curable material. A lower layer can be formed.

In addition, a solvent and various additives can be added to a coating liquid as needed. 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 , Esters such as n-pentyl acetate and γ-ptyrolactone, cellosolves such as methyl cellosolve, cellosolve, butyl cellosolve, cellosolve acetate, alcohols such as methanol, ethanol, isopropyl alcohol, water, etc. It is appropriately selected in consideration of appropriateness and the like. Moreover, a surface adjusting agent, a leveling agent, a refractive index adjusting agent, an adhesion improver, a photosensitizer, etc. can be added to the coating liquid as additives.

  When an ionizing radiation curable material is used as the binder matrix and the low refractive index layer is formed by irradiating with ultraviolet rays, a photopolymerization initiator is added to the coating liquid. Examples of the photopolymerization initiator include acetophenones, benzoins, benzophenones, phosphine oxides, ketals, anthraquinones, thioxanthones, and the like. Thus, the low refractive index layer is formed.

  As described above, the antireflection film of the present invention is formed. In the antireflection film of this invention, it can be set as a polarizing plate by providing a polarizing layer and a transparent base material in the surface at the side of the transparent base material opposite the side in which the antireflection layer is formed. As the polarizing layer, for example, stretched polyvinyl alcohol (PVA) to which iodine is added can be used. Moreover, as another transparent base material, the transparent base material used for an antireflection film can be used, and the film which consists of a triacetyl cellulose can be used conveniently.

  Further, the antireflection film of the present invention is formed into a polarizing plate, and is further provided so that the antireflection layer is the outermost surface on the front side of the transmissive liquid crystal display, that is, the observation side. By providing the antireflection film of the present invention on the surface of the transmissive liquid crystal display, a transmissive liquid crystal display having excellent antistatic function and antireflection function and further reducing the color of reflected light can be obtained. .

Example 1
<Transparent substrate>
As the transparent substrate, a triacetyl cellulose film (refractive index 1.49) having a thickness of 80 μm was used.

<Formation of hard coat layer>
10 parts by weight of dipentaerythritol triacrylate, 10 parts by weight of pentaerythritol tetraacrylate, 30 parts by weight of urethane acrylate (UA-306T manufactured by Kyoeisha Chemical Co., Ltd.) as an ionizing radiation curable material, and Irgacure 184 (Ciba Japan Co., Ltd.) as a photopolymerization initiator A hard coat layer forming coating solution prepared by mixing 2.5 parts by weight of a company (photopolymerization initiator), 50 parts by weight of methyl ethyl ketone and 50 parts by weight of butyl acetate as a solvent was obtained. The triacetyl cellulose film coated with the coating solution for forming the hard coat layer was dried in an oven at 80 ° C. for 1 minute, and after drying, a metal hydride lamp was used. 1 from a distance of 20 cm in output Seconds UV irradiation to form a hard coat layer by performing. Thickness of the obtained hard coat layer is 5 [mu] m, the refractive index was 1.52.

<Formation of antistatic layer>
Tetraethoxysilane was used as a raw material as an organosilicon compound, and isopropyl alcohol and 0.1N hydrochloric acid were added thereto and hydrolyzed to obtain a solution containing a tetraethoxysilane polymer composed of an oligomer. Antimony-doped tin oxide (ATO) fine particles having a primary particle diameter of 8 nm are mixed with this solution, isopropyl alcohol is added, 2.5 parts by weight of a tetraethoxysilane polymer, and antimony-doped tin oxide fine particles in 100 parts by weight of the coating solution. A coating solution for forming an antistatic layer containing 2.5 parts by weight was obtained. On the other hand, the triacetyl cellulose film on which the hard coat layer was formed was immersed in an aqueous 1.5N-NaOH solution at 50 ° C. for 2 minutes for alkali treatment, washed with water, and then added to a 0.5 wt% aqueous H ₂ SO ₄ solution at room temperature. For 30 seconds, neutralized, washed with water and dried. The obtained coating solution for forming an antistatic layer was applied to a wire bar coater on an alkali-treated hard coat layer, and heated and dried in an oven at 120 ° C. for 1 minute to form an antistatic layer. The film thickness of the obtained antistatic layer was 163 nm, the refractive index was 1.53, and the optical film thickness was 250 nm.

<Formation of low refractive index layer>
As an organosilicon compound, tetraethoxysilane and 1H, 1H, 2H, 2H-perfluorooctyltrimethoxysilane mixed at a molar ratio of 95: 5 are used, and isopropyl alcohol and 0.1N hydrochloric acid are added thereto. By hydrolyzing, a solution containing a polymer of an organosilicon compound composed of an oligomer was obtained. Low refractive index silica fine particles having voids are mixed in this solution, isopropyl alcohol is added, and a low refractive index layer is formed containing 2 parts by weight of an organosilicon compound and 2 parts by weight of low refractive index silica fine particles in 100 parts by weight of the coating liquid. A coating solution was obtained. The obtained coating solution for forming a low refractive index layer was applied on a wire bar coater on the antistatic layer, followed by heating and drying in an oven at 120 ° C. for 1 minute to form a low refractive index layer. The film thickness of the obtained low refractive index layer was 91 nm, the refractive index was 1.37, and the optical film thickness was 125 nm. As described above, an antireflection film comprising a hard coat layer, an antistatic layer and a low refractive index layer on a transparent substrate was produced.

(Example 2)
<Formation of transparent substrate and hard coat layer>
In the same manner as in Example 1, a hard coat layer having a film thickness of 5 μm and a refractive index of 1.52 was formed on a triacetylcellulose film (refractive index of 1.49) having a thickness of 80 μm.

<Formation of antistatic layer>
In the same manner as in Example 1, an antistatic layer having a film thickness of 163 nm, a refractive index of 1.53, and an optical film thickness of 250 nm was formed on the alkali-treated hard coat layer.

<Formation of low refractive index layer>
As an organosilicon compound, tetraethoxysilane and 1H, 1H, 2H, 2H-perfluorooctyltrimethoxysilane mixed at a molar ratio of 95: 5 are used, and isopropyl alcohol and 0.1N hydrochloric acid are added thereto. By hydrolyzing, a solution containing a polymer of an organosilicon compound composed of an oligomer was obtained. Low refractive index silica fine particles having voids inside are mixed into this solution, isopropyl alcohol is added, and low weight containing 1.8 parts by weight of organosilicon compound and 2.2 parts by weight of low refractive index silica fine particles in 100 parts by weight of the coating liquid. A coating liquid for forming a refractive index layer was obtained. The obtained coating solution for forming a low refractive index layer was applied on a wire bar coater on the antistatic layer, followed by heating and drying in an oven at 120 ° C. for 1 minute to form a low refractive index layer. The film thickness of the obtained low refractive index layer was 94 nm, the refractive index was 1.33, and the optical film thickness was 125 nm. As described above, an antireflection film comprising a hard coat layer, an antistatic layer and a low refractive index layer on a transparent substrate was produced.

(Comparative Example 1)
<Formation of transparent substrate and hard coat layer>
In the same manner as in Example 1, a hard coat layer having a film thickness of 5 μm and a refractive index of 1.52 was formed on a triacetylcellulose film (refractive index of 1.49) having a thickness of 80 μm.

<Formation of antistatic layer>
Under the same conditions as in Example 1, the triacetyl cellulose film on which the hard coat layer was formed was subjected to alkali treatment. Using the same antistatic layer forming coating solution as in Example 1, the antistatic layer forming coating solution was applied to a wire bar coater on the alkali-treated hard coat layer to form an antistatic layer. The film thickness of the obtained antistatic layer was 82 nm, the refractive index was 1.53, and the optical film thickness was 125 nm.

<Formation of low refractive index layer>
In the same manner as in Example 1, a low refractive index layer having a film thickness of 91 nm, a refractive index of 1.37, and an optical film thickness of 125 nm was formed. As described above, an antireflection film comprising a hard coat layer, an antistatic layer and a low refractive index layer on a transparent substrate was produced.

(Comparative Example 2)
<Formation of transparent substrate and hard coat layer>
In the same manner as in Example 1, a hard coat layer having a film thickness of 5 μm and a refractive index of 1.52 was formed on a triacetylcellulose film (refractive index of 1.49) having a thickness of 80 μm.

<Formation of antistatic layer>
5 parts by weight of dipentaerythritol triacrylate as an ionizing radiation curable material, 5 parts by weight of antimony-doped tin oxide fine particles, Irgacure 184 (manufactured by Ciba Japan Co., Ltd. (photopolymerization initiator) as a photopolymerization initiator, solvent The coating solution for forming an antistatic layer mixed with 90 parts by weight of MIBK was applied as follows: The obtained coating solution for forming an antistatic layer was applied onto a hard coat layer on a wire bar coater and dried in an oven at 80 ° C. for 1 minute. After drying, the film was cured by a conveyor type UV curing device at an exposure amount of 500 mJ / cm ² to form an antistatic layer, and the obtained antistatic layer had a thickness of 78 nm and a refractive index of 1.60. The optical film thickness was 125 nm.

<Formation of low refractive index layer>
The triacetyl cellulose film on which the antistatic layer and the hard coat layer are formed is immersed in a 1.5N-NaOH aqueous solution at 50 ° C. for 2 minutes for alkali treatment, washed with water, and then a 0.5 wt% H ₂ SO ₄ aqueous solution. For 30 seconds at room temperature, neutralized, washed with water and dried. In the same manner as in Example 1, a low refractive index layer having a film thickness of 91 nm, a refractive index of 1.37, and an optical film thickness of 125 nm was formed on the alkali-treated antistatic layer. As described above, an antireflection film comprising a hard coat layer, an antistatic layer and a low refractive index layer on a transparent substrate was produced.

(Comparative Example 3)
<Formation of transparent substrate and hard coat layer>
In the same manner as in Example 1, a hard coat layer having a film thickness of 5 μm and a refractive index of 1.52 was formed on a triacetylcellulose film (refractive index of 1.49) having a thickness of 80 μm.

<Formation of antistatic layer>
Under the same conditions as in Example 1, the triacetyl cellulose film on which the hard coat layer was formed was subjected to alkali treatment. Tetraethoxysilane was used as a raw material as an organosilicon compound, and isopropyl alcohol and 0.1N hydrochloric acid were added thereto and hydrolyzed to obtain a solution containing an oligomeric tetraethoxysilane polymer. Antimony pentoxide fine particles having a primary particle diameter of 20 nm are mixed with this solution, isopropyl alcohol is added, and 2.5 parts by weight of tetraethoxysilane and 2.5 parts by weight of antimony pentoxide fine particles are contained in 100 parts by weight of the coating solution. A layer forming coating solution was obtained. The obtained antistatic layer-forming coating solution was applied to a wire bar coater on an alkali-treated hard coat layer to form an antistatic layer. The film thickness of the obtained antistatic layer was 180 nm, the refractive index was 1.55, and the optical film thickness was 279 nm.

<Formation of low refractive index layer>
In the same manner as in Example 1, a low refractive index layer having a film thickness of 91 nm, a refractive index of 1.37, and an optical film thickness of 125 nm was formed. As described above, an antireflection film comprising a hard coat layer, an antistatic layer and a low refractive index layer on a transparent substrate was produced.

(Comparative Example 4)
<Formation of transparent substrate and hard coat layer>
In the same manner as in Example 1, a hard coat layer having a film thickness of 5 μm and a refractive index of 1.52 was formed on a triacetylcellulose film (refractive index of 1.49) having a thickness of 80 μm.

<Formation of antistatic layer>
Under the same conditions as in Example 1, the triacetyl cellulose film on which the hard coat layer was formed was subjected to alkali treatment. Tetraethoxysilane was used as a raw material as an organosilicon compound, and isopropyl alcohol and 0.1N hydrochloric acid were added thereto, and a solution containing a tetraethoxysilane polymer obtained by hydrolysis was obtained. Antimony pentoxide fine particles having a primary particle size of 20 nm are mixed with this solution, isopropyl alcohol is added, and antistatic charge containing 2.4 parts by weight of tetraethoxysilane and 2.6 parts by weight of antimony pentoxide fine particles in 100 parts by weight of the coating solution. A layer forming coating solution was obtained. The obtained antistatic layer-forming coating solution was applied to a wire bar coater on an alkali-treated hard coat layer to form an antistatic layer. When the film thickness and refractive index of the obtained antistatic layer were measured by an optical simulation method and TEM cross-sectional observation, it was 180 nm, the refractive index was 1.58, and the optical film thickness was 284 nm.

<Formation of low refractive index layer>
In the same manner as in Example 1, a low refractive index layer having a film thickness of 91 nm, a refractive index of 1.37, and an optical film thickness of 125 nm was formed. As described above, an antireflection film comprising a hard coat layer, an antistatic layer and a low refractive index layer on a transparent substrate was produced.

(Comparative Example 5)
<Formation of transparent substrate and hard coat layer>
In the same manner as in Example 1, a hard coat layer having a film thickness of 5 μm and a refractive index of 1.52 was formed on a triacetylcellulose film (refractive index of 1.49) having a thickness of 80 μm.

<Formation of antistatic layer>
Under the same conditions as in Example 1, the triacetyl cellulose film on which the hard coat layer was formed was subjected to alkali treatment. In the same manner as in Example 1, tetraethoxysilane was used as a raw material, and isopropyl alcohol and 0.1N hydrochloric acid were added thereto, and a solution containing a tetraethoxysilane polymer obtained by hydrolysis was obtained. Antimony-doped tin oxide (ATO) fine particles having a primary particle diameter of 8 nm are mixed with this solution, isopropyl alcohol is added, and 2.8 parts by weight of tetraethoxysilane and antimony-doped tin oxide (ATO) fine particles in 100 parts by weight of the coating solution. A coating solution for forming an antistatic layer containing 2.2 parts by weight was obtained. The obtained antistatic layer-forming coating solution was applied to a wire bar coater on an alkali-treated hard coat layer to form an antistatic layer. The film thickness of the obtained antistatic layer was 164 nm, the refractive index was 1.52, and the optical film thickness was 250 nm.

<Formation of low refractive index layer>
In the same manner as in Example 2, a low refractive index layer having a thickness of 94 nm, a refractive index of 1.33, and an optical thickness of 125 nm was formed. As described above, an antireflection film comprising a hard coat layer, an antistatic layer and a low refractive index layer on a transparent substrate was produced.

  The antireflection films obtained in (Example 1), (Example 2), and (Comparative Example 1) to (Comparative Example 5) were evaluated as follows.

-Measurement of spectral reflectance The surface of the obtained antireflection film opposite to the surface on which the low refractive index layer was formed was applied in black by a black matte spray. After spray coating, an automatic spectrophotometer (manufactured by Hitachi, Ltd., U-4000) was used to measure the spectral reflectance at an incident angle of 5 ° for the low refractive index layer forming surface under the condition of a C light source and a 2-degree field of view.
-Measurement of average luminous reflectance and reflection hue The surface of the obtained antireflection film opposite to the surface on which the low refractive index layer was formed was applied in black by a black matte spray. After coating, the average refractive index from the spectral reflectance at an incident angle of 5 ° under the condition of a C light source and a 2-degree field of view on the low refractive index layer forming surface measured using an automatic spectrophotometer (manufactured by Hitachi, U-4000) The reflectance (Y%) and hue (a *, b *) were calculated.
-Evaluation of color unevenness The surface on the opposite side to the low refractive index layer formation surface of the obtained anti-reflective film was apply | coated to black with the black matte spray. After application, the antireflection film was visually observed to observe the occurrence of color unevenness. The evaluation criteria are shown below.
Double circle: Color unevenness is not confirmed even in a dark environment, and color unevenness is difficult to see even in a bright environment. Circle: Color unevenness is not confirmed even in a dark environment, but color unevenness can be confirmed in a bright environment.
Within the allowable range Triangle mark: Color unevenness is confirmed even in a dark environment. Cross: Color unevenness is clearly confirmed even in a dark environment.
-Measurement of surface resistance value It measured in accordance with JIS K6911 with the high-resistance resistivity meter (High Lester MCP-HT260 by Dia Instruments Co., Ltd.).

  In (Example 1), (Example 2), and (Comparative Example 1) to (Comparative Example 5), the film thickness of the hard coat layer was determined by a stylus type film thickness meter. The film thicknesses of the antistatic layer and the low refractive index layer were measured by performing cross-sectional observation with a transmission electron microscope (TEM). Further, the refractive index and optical film thickness of the hard coat layer, antistatic layer, and low refractive index layer were determined by performing optical simulation on the obtained spectral reflectance.

  The spectral reflectances of the antireflection films obtained in (Example 1), (Example 2), and (Comparative Example 1) to (Comparative Example 5) are shown in (FIG. 5) to (FIG. 11).

  (Table 1) shows the evaluation results of the antireflection films obtained in (Example 1), (Example 2), and (Comparative Example 1) to (Comparative Example 5).

In the antireflection films of (Example 1) and (Example 2), the luminous average reflectance is 1.5% or less and has sufficient antireflection performance, and the surface resistance value is 1.0 × 10 ¹⁰ ( Ω / cm ² ) or less, and an antireflection film having sufficient antistatic performance could be obtained. In addition, the reflection hue was in the range of −3 ≦ a * ≦ 3 and 0 ≦ b ≦ 3, and there was little tint, and it was possible to obtain an antireflection film in which in-plane color unevenness was difficult to be confirmed.

  On the other hand, the antireflection film of (Comparative Example 1) has a low average luminous reflectance compared to (Example 1) and can be made an antireflection film excellent in antireflection performance. Is out of the range of −3 ≦ a * ≦ 3 and 0 ≦ b ≦ 3, and the color is large, and the difference between the maximum value and the minimum value of the spectral reflectance is larger than 0.9%. It became an antireflection film in which uneven color was confirmed.

  Further, the antireflection film of (Comparative Example 2) has a large difference in refractive index between the hard coat layer and the antistatic layer, and thus the difference between the maximum value and the minimum value of the spectral reflectance exceeds 0.9%. It became an antireflection film in which color unevenness was clearly confirmed in the surface. Moreover, the reflection hue was also in a place away from the zero point (a * = 0, b * = 0), and it became a colored antireflection film. Further, the surface resistance value on the surface of the low refractive index layer was insufficient.

  Moreover, although the antireflection film of (Comparative Example 3) has sufficient antireflection performance, the difference between the maximum value and the minimum value of the spectral reflectance exceeds 0.9%, and color unevenness in the surface is observed. It became the antireflection film which has. In particular, the amount of change in reflectance on the low wavelength side of the spectral reflectance curve was large, and an antireflection film in which blue color unevenness was confirmed in the surface was obtained. Further, the antireflection film of (Comparative Example 3) exhibited a higher surface resistance value than the surface resistance value of the antireflection film of (Example 1).

  Moreover, the antireflection film of (Comparative Example 4) could be an antireflection film having sufficient antireflection performance and antistatic performance. However, the spectral reflectance curve in the wavelength range of 400 nm to 700 nm has one maximum value, two minimum values, and is W-shaped. Then, when the reflectance changes in the vicinity of 550 nm where the relative visibility is high, green color unevenness was clearly confirmed. In addition, it was confirmed that the reflected hue was also greenish.

  Further, in the antireflection film of (Comparative Example 5), since the refractive index difference between the antistatic layer and the hard coat layer is 0, the antistatic layer cannot function as a high refractive index layer. Therefore, although it has sufficient antireflection performance, the difference between the maximum value and the minimum value of the spectral reflectance cannot be 0.9% or less, and an antireflection film in which color unevenness is confirmed in the surface is obtained. . In the antireflection film of (Comparative Example 5), blue color unevenness was confirmed.

FIG. 1 is a schematic cross-sectional view of the antireflection film of the present invention shown in FIG. FIG. 2 is an explanatory diagram of a spectral reflectance curve (model) of the antireflection film of the present invention. FIG. 3 is a schematic cross-sectional view of a polarizing plate using the antireflection film of the present invention. FIG. 4 shows a transmissive liquid crystal display provided with the antireflection film of the present invention. FIG. 5 is a spectral reflectance curve of the antireflection film obtained in (Example 1). FIG. 6 is a spectral reflectance curve of the antireflection film obtained in (Example 2). FIG. 7 is a spectral reflectance curve of the antireflection film obtained in (Comparative Example 1). FIG. 8 is a spectral reflectance curve of the antireflection film obtained in (Comparative Example 2). FIG. 9 is a spectral reflectance curve of the antireflection film obtained in (Comparative Example 3). FIG. 10 is a spectral reflectance curve of the antireflection film obtained in (Comparative Example 4). FIG. 11 is a spectral reflectance curve of the antireflection film obtained in (Comparative Example 5).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Antireflection film 11 Transparent base material 12 Hard-coat layer 13 Antistatic layer 13A Conductive particle 13B Binder matrix 14 Low refractive index layer 14A Low refractive index particle 14B Binder matrix 2 Polarizing plate 23 Polarizing layer 22 Transparent base material 3 Liquid crystal cell 4 Polarizer 5 Backlight unit

Claims (5)

An antireflection film comprising a hard coat layer, an antistatic layer comprising a binder matrix and conductive particles, and a low refractive index layer comprising a binder matrix and low refractive particles, in order from the transparent substrate side, on at least one surface of the transparent substrate. Because
The transparent substrate has a thickness of 80 μm and a refractive index of 1.49, the hard coat layer has a thickness of 5 μm and a refractive index of 1.52, and the antistatic layer has an optical thickness of 250 μm and a refractive index. An antireflective film having a refractive index of 1.53, the low refractive index layer having an optical film thickness of 125 μm, and a refractive index of 1.33 or 1.37 . 2. The antireflection film according to claim 1 , wherein the conductive particles used in the antistatic layer are electron conductive type conductive particles. The antireflection film according to claim 1, wherein the binder matrix in the antistatic layer and the binder matrix in the low refractive index layer are silica matrices. A polarizing plate comprising a polarizing layer and a transparent substrate film on the surface of the transparent substrate film opposite to the side where the low refractive index layer of the antireflective film according to claim 1 is provided. A polarizing plate comprising a polarizing layer and a transparent substrate film on the surface of the transparent substrate film opposite to the side on which the low refractive index layer of the antireflective film according to claim 1 is provided, a liquid crystal cell A transmissive liquid crystal display comprising a polarizing plate and a backlight unit in this order.

Images