JP2010286657A - Antireflection film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an antireflection film which has low visibility reflectance, can demonstrate an excellent antistatic property and further can suppress interference unevenness and has good black tightness of an image. <P>SOLUTION: The antireflection film is constituted by laminating a hard coat layer and a low refractive index layer on a triacetyl cellulose film (a TAC film) in this order. The hard coat layer is a cured film obtained by curing a composition including a binder component and an antistatic component consisting of an organic electroconductive material with UV rays or the like. As the binder component, UV ray curable multifunctional (meth)acrylate or the like can be suitably used. As the antistatic component, a cationic compound, especially a quaternary ammonium salt, can be suitably used. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention is applied to the surface of a plasma display, a liquid crystal display, an organic EL display, etc., and has an antireflection film that has low visibility reflectance and excellent antistatic properties, and at the same time has good interference unevenness and image blackness. It is about.

  In recent years, electronic image display devices (electronic displays) such as a plasma display, a liquid crystal display, and an organic EL display have made remarkable progress for television and monitor applications, and are widely spread. In these electronic image display devices, there is a problem that visibility decreases due to reflection of external light, adhesion of dust, and the like. Therefore, a method of using an antireflection film formed by providing an antistatic layer and an antireflection layer on the surface of a transparent base film is generally known and used for improving visibility. There is a need for an antireflective film having good antistatic performance at the same time it is subjected to antireflection treatment.

  In order to impart antistatic performance, an antireflection film is disclosed in which metal particles are contained as a conductive filler in a hard coat layer, and a low refractive index layer is laminated on the hard coat layer in order to reduce reflectance. (For example, refer to Patent Document 1).

JP 2004-122611 A (page 2 and pages 5 to 7)

  However, in the antireflection film disclosed in Patent Document 1, the refractive index of the coating itself increases due to the mixing of the metal particles of the conductive filler, resulting in a difference in refractive index from the triacetyl cellulose of the substrate. In order to suppress such a difference in refractive index, interference unevenness is suppressed by including an acrylic compound containing a fluorine atom in the binder. However, the conductive filler metal particles are used for imparting antistatic properties, and the difference in refractive index between the binder and the metal particles is large, and the coating causes whitening due to internal scattering. As a result, there are problems that the haze value increases, the total light transmittance decreases, and the blackness of the image decreases.

  The present invention is intended to solve the above-described problems of the prior art, and the object of the present invention is to have low visibility reflectance, exhibit excellent antistatic properties, and cause uneven interference. An object of the present invention is to provide an antireflection film that is suppressed and has good black tightening for images.

  In order to achieve the above object, the antireflection film of the present invention is an antireflection film in which a hard coat layer and a low refractive index layer are laminated in this order on a triacetyl cellulose film, and the hard coat layer is a binder component. And a cured film obtained by curing a composition containing an antistatic component made of an organic conductive material.

According to the present invention, the following effects can be exhibited.
The antireflection film of the present invention is a composition in which a hard coat layer and a low refractive index layer are laminated in this order on triacetyl cellulose, and the hard coat layer includes a binder component and an antistatic component made of an organic conductive material. Is a cured film obtained by curing Therefore, the antistatic property can be imparted, and the difference in refractive index between the binder component and the antistatic component made of the organic conductive material is small, so that internal scattering does not occur. Tightens. Further, since the refractive index of the hard coat layer and the refractive index of the triacetyl cellulose film can be made equal, the interference unevenness can be reduced.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments embodying the present invention will be described in detail.
<Antireflection film>
In the antireflection film of this embodiment, a hard coat layer and a low refractive index layer are laminated in this order on a triacetyl cellulose film as a transparent resin substrate. The hard coat layer is formed by a cured film obtained by curing a composition containing a binder component and an antistatic component made of an organic conductive material. The components of the antireflection film will be described in order.
<Triacetylcellulose film>
First, a triacetyl cellulose film (hereinafter also referred to as a TAC film) is a polymer in which a hydroxyl group of cellulose is substituted with an acetyl group, and has excellent physical properties such as transparency, electrical insulation and nonflammability, and its refraction. The rate n is 1.49. The thickness of the triacetyl cellulose film is preferably 25 to 200 μm, more preferably 40 to 100 μm. When the thickness is less than 25 μm or exceeds 200 μm, the handleability during the production and use of the antireflection film tends to deteriorate.

The triacetyl cellulose film may contain various additives. Examples of such additives include ultraviolet absorbers, antistatic agents, stabilizers, plasticizers, lubricants, flame retardants, and the like.
<Hard coat layer>
Next, the hard coat layer will be described.

  The hard coat layer is formed from a material containing a binder component and an antistatic component made of an organic conductive material. Here, an ionizing radiation curable resin is used as the binder component, and the ionizing radiation curable resin is a resin that undergoes a curing reaction when irradiated with an active energy ray such as an ultraviolet ray or an electron beam. Not limited. Specifically, for example, monofunctional (meth) acrylate [where (meth) acrylate in this specification means a generic term including both acrylate and methacrylate. ], Starting materials such as polyfunctional (meth) acrylates and reactive silicon compounds such as γ-acryloxypropyltrimethoxysilane. Among these, from the viewpoint of achieving both productivity and hardness, a composition containing an ultraviolet curable polyfunctional (meth) acrylate as a main component is preferable. The composition containing such ultraviolet curable polyfunctional (meth) acrylate is not particularly limited, and for example, a mixture of two or more known ultraviolet curable polyfunctional (meth) acrylates, ultraviolet curable What is marketed as a hard-coat material is mentioned.

  On the other hand, the organic conductive material is a material that can be imparted with an antistatic function by being mixed with a binder component, applied onto a triacetylcellulose film, and cured, and is not particularly limited. What is marketed as a type | mold electrically conductive agent is mentioned. Specifically, various cationic compounds having a cationic group such as quaternary ammonium salt, pyridium salt, phosphonium salt, various anionic compounds having carboxylic acid, sulfonate, phosphate, phosphite, etc., amino alcohols, Examples thereof include nonionic compounds such as glycerin and polyethylene glycol, and amphoteric compounds (betaine compounds) such as amino acids and aminosulfates. Of these organic conductive materials, cationic compounds are preferable, and quaternary ammonium salts are more preferable among them. The antistatic component made of an organic conductive material has a smaller refractive index difference from the binder component than the metal particles that are conventional antistatic agents, so the internal scattering of light in the hard coat layer is suppressed, and the transmittance And the blackness of the image can be improved.

  The mixing amount of the organic conductive material and the ionizing radiation curable resin is preferably 0.1 to 30 parts by mass, more preferably about 1 to 20 parts by mass with respect to 100 parts by mass of the ionizing radiation curable resin. is there. If the addition amount is less than 0.1 parts by mass, sufficient conductivity cannot be exhibited, which is not preferable. On the other hand, if it exceeds 30 parts by mass, it is not preferable because it causes bleed-out and becomes unstable and causes deterioration of physical properties of the film.

  In addition, when the organic conductive material is dispersed in the ionizing radiation curable resin and a cured film is formed, the refractive index of the hard coat layer is preferably in the range of (refractive index of the TAC film) ± 0.03. . In this case, interference unevenness caused by the difference in refractive index between the TAC film and the hard coat layer can be reduced, and the maximum value of the difference in reflectance amplitude in the wavelength region of 500 nm to 650 nm can be made 0.5% or less. More preferably, the refractive index of the hard coat layer is within the range of (refractive index of the TAC film) ± 0.02. If the refractive index of the hard coat layer exceeds (the refractive index of the TAC film) ± 0.03, the interference unevenness is clearly recognized, which is not preferable.

  The film thickness of the hard coat layer is preferably 1 μm to 20 μm. When the thickness of the hard coat layer is less than 1 μm, it is not preferable because sufficient surface strength cannot be obtained. On the other hand, when the film thickness exceeds 20 μm, problems such as a decrease in flex resistance occur, which is not preferable.

  When a hard coat layer is formed on a TAC film by a wet coating method, the dilution solvent is not particularly limited as long as it is an organic solvent. In particular, when a solvent that erodes the surface of the TAC film, such as methyl ethyl ketone, methyl acetate, ethyl acetate or the like, is used alone or mixed with any solvent, the interface between the TAC film and the hard coat layer is disturbed. The interference effect between the film and the hard coat layer interface is suppressed. For this reason, in addition to the effect of the refractive index difference, interference unevenness can be more effectively suppressed.

In addition, other components can be further added to the ionizing radiation curable resin as long as the effects of the present invention are not impaired. Examples of such other components include additives such as a polymer, a polymerization initiator, a polymerization inhibitor, an antioxidant, a dispersant, a surfactant, a light stabilizer, and a leveling agent.
<Low refractive index layer>
Next, the low refractive index layer will be described.

  The refractive index of the low refractive index layer is required to be set lower than that of the hard coat layer, and the difference in refractive index between the hard coat layer and the low refractive index layer is preferably 0.10 to 0.25. The kind of material for forming the low refractive index layer is not particularly limited, and for example, any known low refractive index material may be used. Then, the low refractive index layer is formed by polymerizing and curing the coating solution for the low refractive index layer containing the low refractive index material to form a cured film.

  The cured film forming the hard coat layer and the low refractive index layer is obtained by polymerizing and curing a polyfunctional (meth) acrylate curable coating liquid with a high energy beam such as an electron beam, or starting a thermal decomposition polymerization initiator or photopolymerization. It is obtained by polymerizing and curing a curable coating liquid in the presence of an agent. Among these, a method in which a curable coating liquid containing a photopolymerization initiator is applied to the TAC film surface and then irradiated with ultraviolet rays in an inert gas atmosphere for polymerization and curing is simple and preferable.

  The photopolymerization initiator may be any as long as it has a polymerization initiating ability by ultraviolet irradiation. It is preferable that content of a photoinitiator is 0.1-20 mass% with respect to solid content in a curable coating liquid. When the content of the photopolymerization initiator is less than 0.1% by mass, the polymerization curing of the curable coating liquid becomes insufficient, and when it exceeds 20% by mass, the refractive index of the cured film after polymerization curing increases. Therefore, it is not preferable. The type of ultraviolet lamp used for ultraviolet irradiation is not particularly limited as long as it is generally used. For example, a low-pressure mercury lamp, a high-pressure mercury lamp, an ultrahigh-pressure mercury lamp, a metal halide lamp, a xenon lamp, or the like is used.

  Moreover, it is preferable to set the optical film thickness of the low refractive index layer so that the minimum value of the reflectance of the antireflection film is 450 to 650 nm. The optical film thickness D is represented by D = λ / 4n, where λ is the minimum wavelength of reflectance of the antireflection film, and n is the refractive index of the low refractive index layer.

The formation method of a hard-coat layer and a low-refractive-index layer is not specifically limited, For example, methods, such as a dry coating method and a wet coating method, can be taken. In view of productivity and production cost, the wet coating method is particularly preferable. The wet coating method may be a known method, and typical examples thereof include a roll coating method, a die coating method, a spin coating method, and a dip coating method. In these, the method which can form a layer continuously, such as a roll coat method, is preferable from the point of productivity. The formed layer can be subjected to a curing reaction by heating, irradiation with active energy rays such as ultraviolet rays and electron beams, as necessary.
<Use of antireflection film>
The antireflection film of this embodiment can be used for applications that require a dust adhesion prevention effect, a light interference unevenness suppression effect, and an antireflection effect. In particular, it can be used on the surface of an electronic image display device. Examples of the electronic image display device include a cathode ray tube, a plasma display, a liquid crystal display device, and the like. Then, it can be used directly on the screen surface or in close contact with a plate disposed on the front surface of the screen via an adhesive layer.

Hereinafter, although the said embodiment is described more concretely, giving a manufacture example, an Example, and a comparative example, this invention is not limited to these Examples. In addition, the refractive index of the hardened | cured material coating liquid prepared by the manufacture example and the hardened | cured material of the coating liquid for low refractive index layers was measured as follows.
(1) On a acrylic resin plate (trade name: “Delagrass A”, manufactured by Asahi Kasei Chemicals Corporation) with a refractive index of 1.49, by a dip coater (manufactured by Sugiyama Motoiri Scientific Co., Ltd.) The coating liquid for the low refractive index layer was applied by adjusting the layer thickness so that the optical film thickness was about 550 nm with a dry film thickness.
(2) After drying the solvent, a hard coat layer coating solution or a low refractive index is irradiated with 400 mJ ultraviolet rays using a 120 W high-pressure mercury lamp in a nitrogen atmosphere by an ultraviolet irradiation device (Iwasaki Electric Co., Ltd.) as necessary. The layer coating solution was cured.
(3) The back surface of the acrylic resin plate is roughened with sandpaper and painted with a black paint, and a spectrophotometer (“U-Best V560”, manufactured by JASCO Corporation) is used to measure 5 ° at a light wavelength of 400 to 650 nm, − The 5 ° regular reflectance (spectral reflectance) was measured, and the reflectance minimum value or maximum value was read.
(4) The refractive index was calculated from the extreme value of the reflectance using the following formula.

得られた反射防止フィルムの物性は以下の方法で評価した。

The physical properties of the obtained antireflection film were evaluated by the following methods.

  1) Visibility reflectance Y: Reflection in the XYZ color system defined by JIS Z8701 using the spectral reflectance of light having a wavelength of 400 to 650 nm measured above and the relative spectral distribution of CIE standard illuminant D65. The tristimulus value Y of the object color was calculated.

  2) Maximum value of difference in amplitude of reflectance at light wavelength of 500 to 650 nm: From the reflection spectrum obtained by spectral reflectance measurement, the maximum value of difference in amplitude of reflectance at light wavelength of 500 to 650 nm is calculated. I read it.

3) Haze value: NDH-2000 manufactured by Nippon Denka Kogyo Co., Ltd. was used, and the haze value (%) as an optical property was measured.
4) Total light transmittance: NDH-2000 manufactured by Nippon Denka Kogyo Co., Ltd. was used, and total light transmittance (%) as an optical property was measured.

5) Black tightening of the image: The back surface of the antireflection film was blackened, and the black tightening of the image was observed from the coated surface side, and evaluated according to the following evaluation criteria.
○… Black appears to be tightened. ×… It looks whitish.

6) Surface resistance value: A surface resistance value DSM8103 manufactured by Toa Denpa Kogyo Co., Ltd. was used to measure the surface resistance value.
7) Pencil hardness: Pencil hardness was measured according to JIS K5600-5-4 using a pencil hardness tester manufactured by Yasuda Seiki Co., Ltd.

Next, production examples, examples and comparative examples will be described.
[Production Example 1, Preparation of Hard Coat Layer Coating Liquid (HC-1)]
70 parts by mass of dipentaerythritol hexaacrylate, 30 parts by mass of urethane acrylate, 5 parts by mass of a quaternary ammonium salt (trade name: “1SX-3000”, manufactured by Taisei Fine Chemical Co., Ltd.), 30 parts by mass of methyl ethyl ketone, 70 parts by mass of methanol, A hard polymerization layer coating solution (HC-1) was prepared by mixing 4 parts by mass of a photopolymerization initiator (trade name: “IRGACURE184”, manufactured by Ciba Japan Co., Ltd.). The refractive index of the polymerized cured product of HC-1 was 1.50.
[Production Example 2, Preparation of Hard Coat Layer Coating Liquid (HC-2)]
A hard coat layer coating solution (HC-2) was prepared according to Production Example 1 except that 5 parts by mass of tetramethylammonium sulfate was used as the quaternary ammonium salt instead of 1SX-3000 of Production Example 1. The refractive index of the polymerized cured product of HC-2 was 1.49.
[Production Example 3, Preparation of Hard Coat Layer Coating Liquid (HC-3)]
Dipentaerythritol hexaacrylate 70 parts by mass, urethane acrylate 30 parts by mass, indium tin oxide 7 parts by mass, methyl ethyl ketone 30 parts by mass, methanol 70 parts by mass, photopolymerization initiator (trade name: “IRGACURE184”, manufactured by Ciba Japan Co., Ltd.) 4 parts by mass was mixed to prepare a hard coat layer coating solution (HC-3). The refractive index of the polymerized cured product of HC-3 was 1.53.
[Production Example 3, Preparation of Coating Solution for Low Refractive Index Layer (L-1)]
300 parts by mass of the modified hollow silica sol (trade name: “Thruria NAU”, manufactured by JGC Catalysts & Co., Ltd.), 1,12-bis {(meth) acryloyloxy} -3,10-dihydroxy 5,5,6,6,7 , 7,8,8-octafluorododecane, 40 parts by mass, 5 parts by mass of a photopolymerization initiator (trade name: “KAYACURE BMS”, manufactured by Nippon Kayaku Co., Ltd.), and 650 parts by mass of isopropanol are mixed to obtain a low refractive index. A coating liquid for rate layer (L-1) was prepared. The refractive index of the polymerized cured product of L-1 was 1.35.
Example 1
On a triacetyl cellulose (TAC) film (trade name: “KC8UY”, manufactured by Konica Minolta Opto Co., Ltd., refractive index n = 1.49) having a thickness of 80 μm, a hard coat layer coating solution HC-1 was obtained using a bar coater. Then, the thickness of the layer was adjusted and applied so that the actual film thickness of the cured film was 5 μm, and cured with ultraviolet rays of 400 mJ / cm ² to obtain a hard coat layer. Next, on the hard coat layer, as a low refractive index layer, the low refractive index layer coating liquid L-1 is adjusted by a spin coater so that the optical film thickness of the cured film is 100 nm. After coating and drying, the film was cured with ultraviolet rays of 400 mJ / cm ² under a nitrogen atmosphere to prepare an antireflection film. About the obtained antireflection film, the visibility reflectance, the maximum difference in the amplitude of the reflectance at a light wavelength of 500 to 650 nm, the haze value, the total light transmittance, the blackness of the image, the surface resistivity and the pencil hardness. The results of the evaluation are shown in Table 1.
(Example 2)
An antireflection film was prepared in the same manner as in Example 1 except that the coating liquid for HC-2 was used as the coating liquid for the hard coat layer and the thickness of the cured film was adjusted so that the actual film thickness was 5 μm. Produced. About the obtained antireflection film, the visibility reflectance, the maximum difference in the amplitude of the reflectance at a light wavelength of 500 to 650 nm, the haze value, the total light transmittance, the blackness of the image, the surface resistivity and the pencil hardness. The results of the evaluation are shown in Table 1.
(Comparative Example 1)
An antireflection film was applied in the same manner as in Example 1 except that the coating liquid for HC-3 was used as the coating liquid for the hard coat layer and the thickness of the cured film was adjusted so that the actual film thickness was 5 μm. Produced. About the obtained antireflection film, the visibility reflectance, the maximum difference in the amplitude of the reflectance at a light wavelength of 500 to 650 nm, the haze value, the total light transmittance, the blackness of the image, the surface resistivity and the pencil hardness. The results of the evaluation are shown in Table 1.

表１に示した結果より、実施例１及び２で作製した反射防止フィルムは、適切な屈折率のハードコート層を制御することで、光の波長５００〜６５０ｎｍの反射率の振幅の差の最大値は０．５％以下となっており、干渉むらを低減させることができた。また、有機系導電材料を使用することにより、ヘイズ値が０．５％以下、全光線透過率は９３．０％以上、表面抵抗率は１×１０^１０台であり、画像の黒の締まりは良好であった。このように実施例１及び２では本発明における必要条件を全て満たしているため、反射防止特性、干渉むら、帯電防止性及び画像について黒の締まりの全てを満たしていた。

From the results shown in Table 1, the antireflection films produced in Examples 1 and 2 have a maximum difference in the amplitude of the reflectance of light having a wavelength of 500 to 650 nm by controlling the hard coat layer having an appropriate refractive index. The value was 0.5% or less, and interference unevenness could be reduced. Also, by using an organic conductive material, the haze value is 0.5% or less, the total light transmittance is 93.0% or more, the surface resistivity is 1 × 10 ¹⁰ units, and the blackness of the image is It was good. As described above, in Examples 1 and 2, all the necessary conditions in the present invention were satisfied, so that all of the black tightening was satisfied with respect to the antireflection characteristics, the interference unevenness, the antistatic property and the image.

  On the other hand, in Comparative Example 1, since the refractive index of the hard coat layer was high, uneven interference occurred, the total light transmittance was 90% or less, and the blackness of the image was poor.

Claims (1)

In the antireflection film in which the hard coat layer and the low refractive index layer are laminated in this order on the triacetyl cellulose film,
An antireflection film, wherein the hard coat layer is a cured film obtained by curing a composition containing a binder component and an antistatic component made of an organic conductive material.