JP2005181544A - Antireflection film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coating type and light absorbing type antireflection film in which a low refractive index layer having a low refractive index can be formed on transparent resin film in a short period of time without deteriorating the transparent resin film, and which can be consecutively produced and is excellent in abrasion resistance and chemical resistance. <P>SOLUTION: The antireflection film is constituted by layering an easy adhesion layer 2, a hard coat layer 3, a transparent conductive layer 4, a light absorbing layer 5 and the low refractive index layer 6 in this order on transparent base material film 1 or by layering the hard coat layer, a conductive light absorbing layer and the low refractive index layer in this order on the transparent base material film. The low refractive index layer 6 is hardened by irradiating a coating film containing hollow silica particulates, a multifunctional (meth)acrylic compound and a photopolymerization initiator with ultraviolet rays under an atmosphere where oxygen concentration is 0-10,000 ppm. The light absorbing type antireflection film is set so that its minimum reflectance is ≤0.5%, its transmittance at 550 nm wavelength is ≥70% and its reflectance at 400 nm wavelength is ≤2%. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a coating type light absorption type antireflection film suitable for display surfaces of various displays such as word processors, computers, CRTs, plasma televisions, liquid crystal displays, and organic ELs.

  An antireflection film is applied to display surfaces of various displays such as a word processor, a computer, a CRT, a plasma television, a liquid crystal display, and an organic EL in order to prevent reflection of light and ensure high light transmittance.

  Conventionally, as an antireflection film used for this type of application, a film obtained by providing a high refractive index layer and a low refractive index layer on the surface of a transparent substrate film has been provided. In this antireflection film, an antireflection function is obtained by utilizing the refractive index difference between the high refractive index layer and the low refractive index layer.

Many conventional antireflection films are provided by a dry film forming method in which a low refractive index layer such as SiO ₂ or MgF ₂ and a high refractive index layer such as TiO ₂ or ITO are laminated by vapor deposition or sputtering. However, in the dry method, the film formation takes a very long time, so the cost becomes very high.

  On the other hand, an antireflection film can be produced at a low cost by using a wet film formation method such as a microgravure coating method.

  However, in the wet method, it is difficult to lower the refractive index of the low refractive index component and to increase the refractive index of the high refractive index component, and it is difficult to obtain good antireflection performance. In particular, it is very difficult to lower the refractive index of the low refractive index layer, and various studies have been made on lowering the refractive index of the low refractive index layer.

  Usually, as a low refractive index layer material of a coating type antireflection film, a fluororesin in which part of hydrogen atoms of an alkyl group is substituted with fluorine atoms is used (for example, JP-A-9-203801). ).

Although the refractive index of the low refractive index layer using a fluororesin is low, in order to lower the refractive index, the fluorine-substituted alkyl chain of the fluororesin must be lengthened, while the length of the alkyl chain is lengthened. There is a problem that the film strength of the low refractive index layer is lowered. For example, when a low refractive index layer made of a conventional fluororesin is rubbed with a plastic eraser, film peeling occurs very easily. Even in a low refractive index layer using a fluororesin disclosed in Japanese Patent Laid-Open No. 9-203801, according to the experiments by the present inventors, the addition of the scratch resistance standard (4.9 × 10 ⁴ N / m ² ). When rubbed with a plastic eraser under pressure, the film was broken in about 10 times.

  As a coating-type low refractive index layer, a method has also been proposed in which fine particles having a particle diameter of 1 to 100 nm and a low refractive index (n) are hardened with a binder. Of these, silica fine particles (n = 1.47) hardened with an acrylic binder have high film strength, but the silica fine particles have a relatively high refractive index of about 1.47. It is impossible to make the refractive index of the low refractive index layer to be 1.49 or less.

Further, when MgF ₂ fine particles (n = 1.38) are hardened with an acrylic binder, the refractive index of the low refractive index layer is lowered to some extent (n = 1.46), but compatibility between MgF ₂ and the acrylic binder is achieved. The film strength is very inferior.

  Therefore, compatibility with the binder is good, and hollow silica fine particles (porous silica) are used as fine particles with a low refractive index, and fluorine-substituted alkyl group-containing silicone components are used as binders to improve film strength and reduce the refractive index. It was proposed to plan (Japanese Patent Laid-Open Nos. 2003-202406 and 2003-202960).

  However, in the antireflection film, the base film usually used is a polyethylene terephthalate (PET) film or a triacetyl cellulose (TAC) film, and the PET film cannot be heated at 130 ° C. or more from the viewpoint of heat resistance. . In a wet film-forming method, if a silicone component that cannot be baked by heating or the like is used as a binder, chemical resistance and scratch resistance are very poor. In particular, when immersed in an alkaline aqueous solution (3 wt% NaOH) for about 30 minutes, the silicone component caused alkaline hydrolysis, and the film was easily dissolved. Therefore, in a system mixed with porous silica using a binder containing a silicone component, when the low refractive index layer, which is the outermost layer of the antireflection film, is strongly wiped with an alkali detergent or the like, The prevention function will be lost.

  On the other hand, it has also been proposed to use a polyfunctional acrylic resin having two or more functions as a binder and to form a low refractive index layer containing porous silica fine particles by a wet method (JP-A 2003-261797, JP 2003-262703, JP-A 2003-266602).

  However, according to the study by the present inventors, a film formed by mixing a bifunctional or higher acrylic resin with porous silica fine particles has a very inferior film strength, and a bifunctional or higher acrylic resin is simply made of porous silica. Even when mixed with fine particles, a low refractive index layer having scratch resistance could not be formed. In these publications, the low refractive index layer is formed directly on the surface of the base material. However, when the low refractive index layer is directly formed on the base material in this way, it is indispensable for an antireflection film such as minimum reflectance. A product with excellent antireflection performance cannot be obtained. Moreover, in these publications, porous silica fine particles are used instead of porous silica, but porous silica cannot sufficiently lower the refractive index of silica, so that the refractive index of the low refractive index layer is also sufficient. It will not be low.

  By the way, among the antireflection films, in particular, antireflection films for plasma displays and CRTs, the reflectance on the low wavelength side (400 to 450 nm) is further low, and blue light can be sufficiently transmitted. The transmittance on the side is high, and the transmitted color is required not to be yellowish.

Conventionally, the structure of the antireflection film generally used is as follows, and the reflection spectrum thereof is as shown in FIG.
Configuration 1: Low refractive index layer (n = 1.45) / High refractive index hard coat layer (n = 1.71) / P
ET film configuration 2: low refractive index layer (n = 1.45) / high refractive index hard coat layer (n = 1.68) / T
AC film

  In the configurations 1 and 2, the film thickness of the high refractive index layer and the low refractive index layer is ¼ wavelength (1 / 4λ) of the optical film thickness. In the configuration 1, the antireflection performance is insufficient. At this time, in the configuration 2, the minimum reflectance is as low as about 0.4% at the wavelength of 550 nm, but the reflectance near the wavelength of 450 nm is as high as about 4.5%. ing. As described above, since the reflectance on the low wavelength side is high, this configuration 2 cannot sufficiently transmit blue light. Moreover, since the transmitted light which permeate | transmitted this film will become yellowish when the transmittance | permeability by the side of a low wavelength is low, for example, when white is light-emitted with a display, it will turn yellow.

  In order to reduce the reflectance on the low wavelength side without changing the configuration of the configuration 2, a method of slightly increasing the thickness of the high refractive index layer and decreasing the thickness of the low refractive index layer in the configuration 2 (Configuration 3).

  That is, in the configuration 1, the high refractive index layer and the low refractive index layer were coated with a thickness of about ¼λ of the optical film thickness. The film thickness of 32λ and the low refractive index layer is 0.22λ. A reflection spectrum obtained by comparing the configuration 3 with the configuration 1 is shown in FIG.

  When the high refractive index layer is made thick in this way, the reflectance on the low wavelength side is lowered, but the reflectance at a wavelength of 400 nm is still high at 3.5%. Further, since the minimum reflectance is slightly increased, there is a problem in that the visibility reflectance is increased even if the reflectance on the low wavelength side is decreased. In addition, although the reflectance on the low wavelength side has decreased, it has been necessary to develop an antireflection film that is still as high as 3.5% and that the minimum reflectance and the visibility reflectance are sufficiently low.

  Therefore, the present applicant firstly applied a light absorption type antireflection film in which a hard coat layer, a transparent conductive layer, a light absorption layer, and a low refractive index layer are laminated in this order on a transparent substrate film (Japanese Patent Application No. 2002-318349). No.) or an antireflection film in which a hard coat layer, a conductive light absorption layer and a low refractive index layer are laminated in this order on a transparent substrate film.

  For example, a hard coat layer, a transparent conductive layer, a light absorption layer, and a low refractive index layer are laminated in this order on a transparent substrate film, the thickness of the hard coat layer is 5 to 10 μm, and the thickness of the transparent conductive layer is 0. .35λ, film thickness of light absorbing layer (carbon black / titanium black / acrylic resin, n = 1.63, k = 0.35), 0.15λ, low refractive index layer (silica fine particles / acrylic fine particles, n = 1) .495) is shown in FIG. 4 as a reflection spectrum of the light absorption type antireflection film (Configuration 4).

As shown in FIG. 4, a light absorption type antireflection film having a special configuration in which a transparent conductive layer, a light absorption layer, and a low refractive index layer are formed on a hard coat layer, thereby reducing the reflectance on the low wavelength side. A very low special anti-reflection film could be realized.
JP-A-9-203801 JP 2003-202406 A JP 2003-202960 A JP 2003-261797 A JP 2003-262703 A JP 2003-266602 A Japanese Patent Application No. 2002-318349

  In the low refractive index layer that is the uppermost layer of the antireflection film, not only the low refractive index property but also durability such as scratch resistance and chemical resistance are very important. In addition, a coating-type antireflection film having excellent film performance such as scratch resistance and chemical resistance and having a low refractive index layer having a low refractive index has not been provided.

  Therefore, a low refractive index layer having a low refractive index can be formed on the transparent resin film without degrading the transparent resin film, continuous production is possible, and coating with excellent scratch resistance, chemical resistance, etc. A work-type antireflection film has been desired.

  On the other hand, in the antireflection film for plasma displays and CRT applications that require low reflectance and low transmittance on the low wavelength side, a favorable effect was obtained by adopting the configuration 4, but this configuration 4 Even so, there was still a problem to be solved.

  In a normal antireflection film (configuration 1) that does not use a light absorption layer, the transmittance hardly changed even if the low refractive index layer was flawed. In the case of the light absorption type antireflection film having this constitution 4, if the low refractive index layer is damaged even a little, even the light absorption layer is peeled off, and the place where the light absorption layer is peeled becomes very high in transmittance. The scratches will be very noticeable. Therefore, the antireflection film using the light absorbing layer is required to have a remarkably high scratch resistance of the low refractive index layer.

  However, when the film strength of the low-refractive index layer is increased, the refractive index of the low-refractive index layer becomes very high, about n = 1.49, and a sufficiently low refractive index cannot be achieved. In the configuration 4, when the refractive index of the low refractive index layer is high, in order to obtain a minimum reflectance of 0.5% or less, it is necessary to form a thick light absorption layer. However, if the light absorption layer is thick, There is a problem that the transmittance is as low as 70% or less.

  The present invention has been made in view of the above-described conventional situation, and a low refractive index layer having a low refractive index can be formed on a transparent resin film without degrading the transparent resin film, enabling continuous production. Then, it aims at providing the coating type antireflection film excellent also in abrasion resistance, chemical-resistance, etc.

  In particular, the present invention provides an antireflection film obtained by laminating a hard coat layer, a transparent conductive layer, a light absorbing layer and a low refractive index layer in this order on a transparent base film, or a hard coat on a transparent base film. In the antireflection film in which the layer, the conductive light absorption layer and the low refractive index layer are formed in this order, by forming a low refractive index layer having a low refractive index and excellent scratch resistance, The object of the present invention is to provide a light-absorbing antireflection film that has a low reflectivity, can sufficiently transmit blue light, has a low transmittance on the low wavelength side, and does not have a yellow transmission color. .

  The antireflection film of the present invention is an antireflection film obtained by laminating a hard coat layer, a transparent conductive layer, a light absorption layer and a low refractive index layer in this order on a transparent base film, or a transparent base film. In the antireflection film comprising a hard coat layer, a conductive light absorption layer and a low refractive index layer in this order, the low refractive index layer is hollow silica fine particles (hereinafter referred to as “porous silica”). In a coating film containing a polyfunctional (meth) acrylic compound, that is, a (meth) acrylic compound having two or more (meth) acryloyl groups, and a photopolymerization initiator, in an atmosphere having an oxygen concentration of 0 to 10,000 ppm It is cured by irradiating with ultraviolet rays, and has a minimum reflectance of 0.5% or less, a transmittance at a wavelength of 550 nm of 70% or more, and a reflectance at a wavelength of 400 nm of 2% or less. To.

  The porous silica used in the present invention has a low refractive index and is effective as a material for the low refractive index layer. Further, by selecting a polyfunctional (meth) acrylic compound as a binder component, it is possible to impart scratch resistance, chemical resistance, and antifouling property, and to form a good low refractive index layer. . Moreover, since the low refractive index layer according to the present invention is cured by irradiation with ultraviolet rays under specific low oxygen conditions, it is refracted in continuous production without applying heat, and without degrading the transparent resin film. A low refractive index layer having a very low rate and excellent scratch resistance and chemical resistance can be formed. For this reason, an antireflection film having a minimum reflectance of 0.5% or less, a transmittance of 70% or more at 550 nm of the hard coat layer, and a reflectance of 2% or less at a wavelength of 400 nm can be realized.

  That is, the present inventors conducted a follow-up experiment on the above-described conventional technology, and when a low refractive index layer was formed by mixing bifunctional or higher acrylic resin with porous silica fine particles, the film strength was very low. It has been found that the scratch resistance is not improved at all even when a bifunctional or higher functional acrylic resin is mixed with the porous silica fine particles. Further, it has been found that even when the low refractive index layer is directly formed on the substrate surface, the antireflection performance indispensable for the antireflection film such as the minimum reflectance is insufficient.

  Further, it has been found that the porous silica fine particles cannot have a sufficiently low refractive index of silica, and it is necessary to use porous silica for further lowering the refractive index.

  Based on these findings, the present inventors firstly made a transparent base film / hard coat layer / transparent conductive layer / light absorption layer / low refractive index layer, or transparent base film / easy for film configuration. The antireflection performance was improved by using an adhesive layer / hard coat layer / conductive light absorbing layer / low refractive index layer. And, by applying ultraviolet rays under very low oxygen concentration conditions to cure the binder, the scratch resistance of the low refractive index layer can be greatly increased, especially when a special acrylic resin is used as the binder. The inventors have found that strong scratch resistance and chemical resistance can be obtained, and completed the present invention.

In the present invention, an easy adhesion layer is provided on the transparent base film, and the transparent base film / easy adhesion layer / hard coat layer / transparent conductive layer / light absorption layer / low refractive index layer, or transparent base film / It is preferable to have a laminated structure of an easy adhesion layer / hard coat layer / conductive light absorption layer / low refractive index layer. In this case, the range of the refractive index of the hard coat layer is 1.48 to 1.55, a refractive index n _a of the adhesive _layer, the refractive index n _b of the transparent substrate _film, the refraction of the hard coat layer If the rate is n _HC ,
(N _b + n _HC ) / 2 −0.03 ≦ n _a ≦ (n _b + n _HC ) / 2 +0.03
The film thickness T of the easy adhesion layer is
(550/4) × (1 / n _a ) −10 nm ≦ T ≦ (550/4) × (1 / n _a ) +10 nm
When an easy-adhesion layer in the range is provided, remarkably excellent antireflection performance can be obtained.

  This is because light having a wavelength of 550 nm has an effect that the refractive index of the base film is substantially equal to the refractive index of the hard coat layer, and there is no reflection between the hard coat layer and the base film. In this invention, it is preferable that this easily bonding layer is what was formed on the transparent base film at the time of shaping | molding of this transparent base film.

  In the present invention, the polyfunctional (meth) acrylic compound as the binder component is a hexafunctional (meth) acrylic compound represented by the following general formula (I) and / or 4 represented by the following general formula (II). It is preferable to use a functional (meth) acrylic compound as a main component. Here, the main component means that it contains 50% by weight or more of the total binder component.

（上記一般式（Ｉ）中、Ａ^１〜Ａ^６は各々独立に、アクリロイル基、メタクリロイル基、α−フルオロアクリロイル基、又はトリフルオロメタクリロイル基を表し、
ｎ，ｍ，ｏ，ｐ，ｑ，ｒは各々独立に、０〜２の整数を表し、
Ｒ^１〜Ｒ^６は各々独立に、炭素数１〜３のアルキレン基、或いは、水素原子の１個以上がフッ素原子に置換された炭素数１〜３のフルオロアルキレン基を表す。）

(In the general formula (I), A ^{1 to} A ⁶ each independently represents an acryloyl group, a methacryloyl group, an α-fluoroacryloyl group, or a trifluoromethacryloyl group,
n, m, o, p, q and r each independently represent an integer of 0 to 2;
R ^{1 to} R ⁶ each independently represents an alkylene group having 1 to 3 carbon atoms, or a fluoroalkylene group having 1 to 3 carbon atoms in which one or more hydrogen atoms are substituted with fluorine atoms. )

（上記一般式（II）中、Ａ^１１〜Ａ^１４は各々独立に、アクリロイル基、メタクリロイル基、α−フルオロアクリロイル基、又はトリフルオロメタクリロイル基を表し、
ｓ，ｔ，ｕ，ｖは各々独立に、０〜２の整数を表し、
Ｒ^１１〜Ｒ^１４は各々独立に、炭素数１〜３のアルキレン基、或いは、水素原子の１個以上がフッ素原子に置換された炭素数１〜３のフルオロアルキレン基を表す。）

(In the general formula (II), A ^{11 to} A ¹⁴ each independently represents an acryloyl group, a methacryloyl group, an α-fluoroacryloyl group, or a trifluoromethacryloyl group,
s, t, u, v each independently represents an integer of 0-2,
R ^{11 to} R ¹⁴ each independently represents an alkylene group having 1 to 3 carbon atoms or a fluoroalkylene group having 1 to 3 carbon atoms in which one or more hydrogen atoms are substituted with fluorine atoms. )

  Further, the surface of the porous silica is obtained by a terminal (meth) acrylsilane coupling agent represented by the following general formula (IV), preferably by a hydrothermal reaction at 100 to 150 ° C. or by a reaction under microwave irradiation. A terminal (meth) acryl-modified (meth) acryl-modified porous silica is preferable, and thereby the scratch resistance of the low refractive index layer can be improved.

（上記一般式(IV)中、Ｒ^２１は水素原子、フッ素原子又はメチル基を表し、
Ｒ^２２は炭素数１〜８のアルキレン基、又は、水素原子の１個以上がフッ素原子に置換された炭素数１〜８のフルオロアルキレン基を表し、
Ｒ^２３〜Ｒ^２５は各々独立に、水素原子又は炭素数１〜４のアルキル基を表す。）

(In the general formula (IV), R ²¹ represents a hydrogen atom, a fluorine atom or a methyl group,
R ²² represents an alkylene group having 1 to 8 carbon atoms or a fluoroalkylene group having 1 to 8 carbon atoms in which one or more hydrogen atoms are substituted with fluorine atoms,
R ^{23 to} R ²⁵ each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. )

  Porous silica has a terminal fluoroalkylsilane coupling agent represented by the following general formula (V), preferably by a hydrothermal reaction at 100 to 150 ° C., or by a reaction under microwave irradiation, so that the surface has terminal fluoroalkyl. It is preferably an alkyl-modified fluoroalkyl-modified porous silica, which can improve the antifouling property of the low refractive index layer.

（上記一般式（Ｖ）中、Ｒ^３１〜Ｒ^３３は各々独立に、水素原子又は炭素数１〜４のアルキル基を表し、ｙａは１〜８の整数を表し、ｙｂは１〜３の整数を表す。）

(In said general formula (V), R < ³¹ > -R < ³³ > represents a hydrogen atom or a C1-C4 alkyl group each independently, ya represents the integer of 1-8, yb is the integer of 1-3. Represents.)

In the present invention, the transparent conductive layer is formed by curing at least one fine particle selected from the group consisting of ATO, ZnO, Sb ₂ O ₅ , SnO ₂ , ITO, and In ₂ O ₃ with a (meth) acrylic binder resin. It is preferable that the film thickness is 80 to 200 nm. The light absorption layer includes carbon black fine particles and titanium nitride fine particles, and the complex refractive index of the light absorption layer is n + ik.
The value of n is 1.45 to 1.75
The value of k is 0.1 to 0.35
It is preferable that

The conductive light absorption layer includes carbon black fine particles, and the complex refractive index of the light absorption layer is n + ik.
The value of n is 1.45 to 1.75
The value of k is 0.1 to 0.35
It is preferable that

  In the present invention, when the transparent substrate film is a PET film, it is preferable that an easy adhesion layer having a refractive index of 1.55 to 1.61 and a film thickness of 75 to 95 nm is formed on the hard coat layer side. .

  According to the present invention, a low refractive index layer having a low refractive index can be formed on a transparent resin film in a short time without deteriorating the transparent resin film, and continuous production is possible. A coating-type antireflection film excellent in properties and the like is provided.

  In particular, the antireflective film of the present invention can form a low refractive index layer having a very low refractive index that is remarkably excellent in scratch resistance in an antireflective film provided with a light absorbing layer, thereby absorbing light. The transmittance can be increased by reducing the thickness of the layer. For this reason, it is possible to realize an antireflection film having a high transmittance and a low reflectance such as a minimum reflectance of 0.5% or less, a transmittance of 70% or more at a hard coat layer of 550 nm, and a reflectance of 2% or less at a wavelength of 400 nm. Suitable for plasma display and CRT applications.

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

  As shown in FIG. 1, the antireflection film of the present invention comprises an easy adhesion layer 2, a hard coat layer 3, a transparent conductive layer 4, a light absorption layer 5 and a low refractive index layer 6 in this order on a transparent substrate film 1. It is formed by laminating. Alternatively, in FIG. 1, a conductive light absorption layer is provided instead of the transparent conductive layer and the light absorption layer.

  In the present invention, the base film 1 includes polyester, polyethylene terephthalate (PET), polybutylene terephthalate, polymethyl methacrylate (PMMA), acrylic, polycarbonate (PC), polystyrene, cellulose triacetate (TAC), polyvinyl alcohol, poly Vinyl chloride, polyvinylidene chloride, polyethylene, ethylene-vinyl acetate copolymer, polyurethane, cellophane, etc., preferably PET, PC, PMMA transparent films.

  The thickness of the base film 1 is appropriately determined depending on the required properties (for example, strength and thin film properties) depending on the use of the obtained antireflection film, and is usually in the range of 1 μm to 10 mm.

  As the transparent substrate film, a PET film is particularly preferable. In the case of a PET film, an easy-adhesion layer having a refractive index of 1.55 to 1.61 and a film thickness of 75 to 95 nm is provided on the hard coat layer side of the PET film. The coating is preferable from the viewpoint of lowering the minimum reflectance and eliminating interference blur.

The easy-adhesion layer 2 is for improving the adhesion of the hard coat layer 3 to the base film 1. Usually, a thermosetting resin such as a copolymerized polyester resin and a polyurethane resin is added to SiO ₂ , ZrO. ₂ , metal oxide fine particles such as TiO ₂ and Al ₂ O ₃ , preferably metal oxide fine particles having an average particle diameter of about 1 to 100 nm are blended to adjust the refractive index. Note that the refractive index can be set to 1.58 using only the resin.

  The hard coat layer 3 on the transparent substrate film 1 can be formed by applying a normal hard coat agent such as an acrylic resin or a silicone resin. If necessary, this hard coat layer may be blended with about 0.05 to 5% by weight of a known ultraviolet absorbing material to impart ultraviolet cut performance. The film thickness of the hard coat layer 3 is preferably about 2 to 20 μm.

In the present invention, it is preferable that the refractive index of the hard coat layer 3 is in the range of 1.48 to 1.55, in this case, the refractive index of the adhesion layer 2 n _a, a transparent base film 1 refraction When the refractive index is n _b and the refractive index of the hard coat layer 3 is n _HC ,
(N _b + n _HC ) / 2 −0.03 ≦ n _a ≦ (n _b + n _HC ) / 2 +0.03
In particular, (n _b + n _HC ) /2−0.01≦n _a ≦ (n _b + n _HC ) / 2 +0.01
And the film thickness T of the easy adhesion layer 2 is
(550/4) × (1 / n _a ) −10 nm ≦ T ≦ (550/4) × (1 / n _a ) +10 nm
Above all
(550/4) × (1 / n _a ) −5 nm ≦ T ≦ (550/4) × (1 / n _a ) +5 nm
Since it is possible to obtain remarkably excellent antireflection performance when the thickness is in the range, it is preferable.

The transparent conductive layer 4 on the hard coat layer 3 is preferably a group consisting of ATO (antimony-doped tin oxide), ZnO, Sb ₂ O ₅ , SnO ₂ , ITO (indium tin oxide), and In ₂ O _3. A coating liquid obtained by mixing at least one conductive fine particle selected from the above with an acrylic binder component is applied onto the hard coat layer 3 formed on the easy-adhesion layer 2 of the transparent substrate film 1. The resulting coating film is preferably formed by photocuring.

  The mixing ratio of the conductive fine particles and the binder component in the coating liquid is appropriately determined depending on the refractive index of the transparent conductive layer 4 to be formed, but preferably the binder component: conductive fine particles = 100: 200 to 700 ( Weight ratio).

  The film thickness of the transparent conductive layer 4 is preferably 80 to 200 nm. If the thickness of the transparent conductive layer 4 is thinner than this range, sufficient conductivity cannot be obtained, and the resulting antireflection film has a high surface resistance value. If the transparent conductive layer 4 is excessively thick, the optical performance (antireflection performance) is extremely lowered.

  In addition, it is preferable that the electroconductive fine particles used for formation of the transparent conductive layer 4 are 5-100 nm in average particle diameter.

  The light absorbing layer 5 is preferably formed on the transparent conductive layer 4 with at least one kind of light absorbing fine particles selected from the group consisting of metal oxide, metal nitride, and carbon, and particularly preferably carbon black fine particles. It is formed by coating a coating liquid obtained by mixing a mixture of titanium nitride fine particles with an acrylic binder or the like on the transparent conductive layer 4 and preferably photocuring the obtained coating film. .

  The mixing ratio of the light-absorbing fine particles and the binder component in the coating liquid is appropriately determined depending on the attenuation coefficient of the light-absorbing layer 5 to be formed. In the present invention, the light-absorbing fine particles and the binder component The mixing ratio of the binder component: light-absorbing fine particles = 100 to 700 to 700 is appropriately adjusted so that the complex refractive index of the light-absorbing layer is n + ik, and n = 1.45 to 1.75, k = 0. It is preferable to form a light absorption layer of 0.1 to 0.35 in order to obtain good antireflection performance.

  The thickness of the light absorption layer 5 is preferably 20 to 100 nm. When the film thickness of the light absorption layer 5 is thicker than this range, the transmittance decreases. However, if the thickness of the light absorption layer 5 is excessively thin, sufficient antireflection performance cannot be obtained, which is not preferable.

  In the case where a conductive light absorbing layer is formed instead of the transparent conductive layer and the light absorbing layer, the conductive light absorbing layer is preferably composed of conductive light absorbing fine particles such as carbon black as an acrylic binder component. It is formed by coating the coating liquid formed by mixing on the hard coat layer and preferably photocuring the obtained coating film.

  The mixing ratio of the conductive light-absorbing fine particles and the binder component in the coating liquid is appropriately determined depending on the attenuation coefficient of the conductive light-absorbing layer to be formed. In the present invention, this conductive light-absorbing property is determined. By appropriately adjusting the mixing ratio of the fine particles and the binder component in the range of binder component: conductive light absorbing fine particles = 100 to 100 to 700, assuming that the complex refractive index of the conductive light absorbing layer is n + ik, n = 1. Forming a conductive light absorbing layer of 45 to 1.75, k = 0.1 to 0.35 is preferable for obtaining good antireflection performance.

  The thickness of such a conductive light absorption layer is preferably 20 to 100 nm. If the thickness of the conductive light absorbing layer is larger than this range, the transmittance is lowered. However, if the thickness of the conductive light absorption layer is excessively thin, sufficient antireflection performance cannot be obtained, which is not preferable.

  In the present invention, the low refractive index layer 6 applies ultraviolet light to a coating film containing a binder component composed of porous silica and a polyfunctional (meth) acrylic compound and a photopolymerization initiator in an atmosphere having an oxygen concentration of 0 to 10,000 ppm. It is cured by irradiation.

  Porous silica is hollow shell-like silica fine particles, and the average particle size is preferably 10 to 200 nm, and more preferably 10 to 150 nm. If the average particle size of the porous silica is less than 10 nm, it is difficult to lower the refractive index of the porous silica. If the average particle size exceeds 200 nm, light is diffusely reflected, and the surface roughness of the formed low refractive index layer is increased. The problem comes out.

  Porous silica has air having a low refractive index (refractive index = 1.0) inside the hollow, and therefore its refractive index is significantly lower than that of ordinary silica (refractive index = 1.46). The refractive index of the porous silica is determined by the volume ratio of the hollow part, but is usually preferably about 1.20 to 1.40.

The refractive index of porous silica: n (porous silica) is as follows from the refractive index of silica constituting the shell of hollow fine particles: n (silica) and the refractive index of air inside: n (air). Is required.
n (porous silica) = n (silica) × silica volume fraction

  As described above, since n (silica) is about 1.47 and n (air) is as low as 1.0, the refractive index of such porous silica is very low.

The refractive index of the low refractive index layer according to the present invention using such porous silica: n (low refractive index layer) is the refractive index of porous silica: n (porous silica) and the refractive index of the binder component: n. From (binder), it is obtained as follows.
n (low refractive index layer) =
n (porous silica) × volume ratio of porous silica in the low refractive index layer + n (binder) × volume ratio of binder in the low refractive index layer

  Here, since the refractive index of the binder is about 1.50 to 1.55 except for the special fluorine-containing acrylic binder, increasing the volume fraction of the porous silica in the low refractive index layer can reduce the refractive index. This is an important requirement for reducing the refractive index of the refractive index layer.

  In the present invention, the higher the content of porous silica in the low refractive index layer, the lower the refractive index layer can be formed and the antireflection film excellent in antireflection performance can be obtained. When the content of the binder component is relatively reduced, the film strength of the low refractive index layer is lowered, and the scratch resistance and durability are lowered. However, the decrease in film strength due to the increase in the amount of porous silica can be compensated for by surface treatment of porous silica, and the film strength can also be supplemented by selecting the type of binder component to be blended. it can.

  In the present invention, the porous silica content in the low refractive index layer is set to 20 to 50% by weight, particularly 25 to 50% by weight, depending on the surface treatment of the porous silica and the selection of the binder component. The refractive index is preferably about 1.39 to 1.45, and it is preferable to ensure scratch resistance.

  Next, the polyfunctional (meth) acrylic compound which is a binder component of the low refractive index layer of the present invention will be described.

  This polyfunctional (meth) acrylic compound is a hexafunctional (meth) acrylic compound represented by the following general formula (I) and / or a tetrafunctional (meth) acrylic compound represented by the following general formula (II): It is preferable that 50% by weight or more, particularly 80% by weight or more is contained in all the binder components.

（上記一般式（Ｉ）中、Ａ^１〜Ａ^６は各々独立に、アクリロイル基、メタクリロイル基、α−フルオロアクリロイル基、又はトリフルオロメタクリロイル基を表し、
ｎ，ｍ，ｏ，ｐ，ｑ，ｒは各々独立に、０〜２の整数を表し、
Ｒ^１〜Ｒ^６は各々独立に、炭素数１〜３のアルキレン基、或いは、水素原子の１個以上がフッ素原子に置換された炭素数１〜３のフルオロアルキレン基を表す。）

(In the general formula (I), A ^{1 to} A ⁶ each independently represents an acryloyl group, a methacryloyl group, an α-fluoroacryloyl group, or a trifluoromethacryloyl group,
n, m, o, p, q and r each independently represent an integer of 0 to 2;
R ^{1 to} R ⁶ each independently represents an alkylene group having 1 to 3 carbon atoms, or a fluoroalkylene group having 1 to 3 carbon atoms in which one or more hydrogen atoms are substituted with fluorine atoms. )

（上記一般式（II）中、Ａ^１１〜Ａ^１４は各々独立に、アクリロイル基、メタクリロイル基、α−フルオロアクリロイル基、又はトリフルオロメタクリロイル基を表し、
ｓ，ｔ，ｕ，ｖは各々独立に、０〜２の整数を表し、
Ｒ^１１〜Ｒ^１４は各々独立に、炭素数１〜３のアルキレン基、或いは、水素原子の１個以上がフッ素原子に置換された炭素数１〜３のフルオロアルキレン基を表す。）

(In the general formula (II), A ^{11 to} A ¹⁴ each independently represents an acryloyl group, a methacryloyl group, an α-fluoroacryloyl group, or a trifluoromethacryloyl group,
s, t, u, v each independently represents an integer of 0-2,
R ^{11 to} R ¹⁴ each independently represents an alkylene group having 1 to 3 carbon atoms or a fluoroalkylene group having 1 to 3 carbon atoms in which one or more hydrogen atoms are substituted with fluorine atoms. )

  Examples of the hexafunctional (meth) acrylic compound represented by the general formula (I) include dipentaerythritol hexaacrylate, ethylene oxide adduct of dipentaerythritol hexaacrylate, or ethylene oxide H-substituted fluorine These may be used alone or in combination of two or more.

  Examples of the tetrafunctional (meth) acrylic compound represented by the general formula (II) include pentaerythritol tetraacrylate, pentaerythritol tetraacrylate ethylene oxide adduct (1-8), or ethylene oxide The thing which fluorine-substituted H etc. are mentioned, These may be used individually by 1 type and may use 2 or more types together.

  As the binder component, one or more of hexafunctional (meth) acrylic compounds represented by the general formula (I) and a tetrafunctional (meth) acrylic compound represented by the general formula (II) are used. You may use together 1 type, or 2 or more types.

  The polyfunctional (meth) acrylic compound represented by the general formulas (I) and (II), particularly the hexafunctional (meth) acrylic compound represented by the general formula (I) has high hardness and scratch resistance. It is effective for forming a low refractive index layer that is excellent and has high scratch resistance.

In the present invention, as a binder component, a hexafunctional (meth) acrylic compound represented by the general formula (I) and / or a tetrafunctional (meth) acrylic compound represented by the general formula (II). In addition, a fluorine-containing bifunctional (meth) acrylic compound represented by the following general formula (III) or a specific fluorine-containing polyfunctional (meth) acrylic compound is preferably used in combination, and these binder components are used. This makes it possible to impart scratch resistance and antifouling properties to the low refractive index layer. These binder components have a refractive index higher than that of the hexafunctional (meth) acrylic compound represented by the general formula (I) or the tetrafunctional (meth) acrylic compound represented by the general formula (II). Since it is low, a low refractive index layer having a low refractive index can be formed even if the blending amount of porous silica is reduced.
^{_{A a -O- (CH 2) xa}} -Rf- (CH 2) xb -O-A b ...... (III)
(In the general formula (III), A ^a and A ^b each independently represents an acryloyl group, a methacryloyl group, an α-fluoroacryloyl group, or a trifluoromethacryloyl group, Rf represents a perfluoroalkylene group, xa, xb represents each independently an integer of 0 to 3.)
Examples of the fluorine-containing bifunctional (meth) acrylic compound represented by the general formula (III) include 2,2,3,3,4,4-hexafluoropentane glycol diacrylate and the like. May be used alone or in combination of two or more.

  In addition, the above specific polyfunctional (meth) acrylic compound, that is, a 3-6 functional (meth) acrylic compound having 6 or more fluorine atoms in one molecule and a molecular weight of 1000 or less, fluorine in one molecular weight As for a 6-15 functional (meth) acrylic compound having 10 or more atoms and a molecular weight of 1000 to 5000, one kind may be used alone, or two or more kinds may be used in combination.

  You may use together the 1 type (s) or 2 or more types of the said fluorine-containing bifunctional (meth) acrylic-type compound, and 1 type, or 2 or more types of a fluorine-containing polyfunctional (meth) acrylic-type compound.

  By using the fluorine-containing bifunctional (meth) acrylic compound, it is possible to reduce the refractive index of the low refractive index layer and improve the antifouling property. However, if the blending amount is excessively large, scratch resistance is obtained. descend. Therefore, the fluorine-containing bifunctional (meth) acrylic compound is preferably blended in an amount of 5% by weight or more, particularly 5 to 10% by weight, in all binder components.

  Also, the use of the fluorine-containing polyfunctional (meth) acrylic compound can reduce the refractive index and improve the antifouling property of the low refractive index layer. Sex is reduced. Accordingly, the polyfunctional (meth) acrylic compound is preferably blended in an amount of 5% by weight or more, particularly 5 to 10% by weight, in all binder components.

  In addition, when using together a fluorine-containing bifunctional (meth) acrylic compound and a fluorine-containing polyfunctional (meth) acrylic compound, a fluorine-containing bifunctional (meth) acrylic compound and a fluorine-containing polyfunctional (meth) acrylic compound And 5% by weight or more, particularly 5 to 10% by weight, is preferably added to all the binder components.

  Since the porous silica used in the present invention has a larger particle size than general silica fine particles (particle size of about 5 to 20 nm) blended in a conventional low refractive index layer, even when the same binder component is used, Compared to the case where silica fine particles are blended, the film strength of the low refractive index layer formed tends to be weak, but by applying an appropriate surface treatment to this porous silica, the binding strength with the binder component is increased, Scratch resistance can be improved by increasing the film strength of the formed low refractive index layer.

  As the surface treatment of the porous silica, it is preferable that the surface of the porous silica is modified with a terminal (meth) acryl by using a terminal (meth) acrylsilane coupling agent represented by the following general formula (IV).

（上記一般式(IV)中、Ｒ^２１は水素原子、フッ素原子又はメチル基を表し、
Ｒ^２２は炭素数１〜８のアルキレン基、又は、水素原子の１個以上がフッ素原子に置換された炭素数１〜８のフルオロアルキレン基を表し、
Ｒ^２３〜Ｒ^２５は各々独立に、水素原子又は炭素数１〜４のアルキル基を表す。）

(In the general formula (IV), R ²¹ represents a hydrogen atom, a fluorine atom or a methyl group,
R ²² represents an alkylene group having 1 to 8 carbon atoms or a fluoroalkylene group having 1 to 8 carbon atoms in which one or more hydrogen atoms are substituted with fluorine atoms,
R ^{23 to} R ²⁵ each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. )

As such a terminal (meth) acryl silane coupling agent, for example, CH ₂ ═CH—COO— (CH ₂ ) ₃ —Si— (OCH ₃ ) ₃ , CH ₂ ═C (CH ₃ ) —COO— (CH ₂ ) ₃ —Si— (OCH ₃ ) _{3 and the} like, and these may be used alone or in combination of two or more.

  In order to modify the surface of the porous silica with the terminal (meth) acryl silane coupling agent, the mixture of the porous silica and the terminal (meth) acryl silane coupling agent at 100 to 150 ° C. It is preferable to cause a hydrothermal reaction, or to react this mixed solution by irradiating it with microwaves. That is, by simply mixing the terminal (meth) acrylsilane coupling agent and the porous silica, the surface chemical modification with the terminal (meth) acrylsilane coupling agent cannot be performed, and the desired surface modification effect is achieved. Can't get. Also in the case of hydrothermal reaction, if the reaction temperature is low, sufficient terminal (meth) acryl modification cannot be performed. However, if this reaction temperature is too high, the reactivity is conversely reduced, so the hydrothermal reaction temperature is preferably 100 to 150 ° C. The hydrothermal reaction time is usually about 0.1 to 10 hours, although it depends on the reaction temperature. On the other hand, in the case of using microwaves, if the set temperature is too low, sufficient terminal (meth) acryl modification cannot be performed. For the same reason as described above, the set temperature is preferably 90 to 150 ° C. As the microwave, one having a frequency of 2.5 GHz can be suitably used. If microwave irradiation is performed, terminal (meth) acryl modification can be performed in a short time of usually about 10 to 60 minutes. Examples of the mixed solution used in this reaction include 3.8% by weight of porous silica, 96% by weight of an alcohol solvent (1: 4 (weight ratio) mixed solvent of isopropyl alcohol and isobutyl alcohol), 3% by weight of acetic acid, and water 1 The reaction solution prepared by weight% and the silane coupling agent 0.04 weight% is mentioned.

  By chemically modifying the surface of the porous silica with such a terminal (meth) acryl silane coupling agent, the porous silica and the binder component are firmly bonded, and even when the amount of the porous silica is large, A low refractive index layer having excellent scratch resistance can be formed, and the amount of porous silica added can be increased to lower the refractive index of the low refractive index layer.

  Further, the porous silica may have a surface modified with a terminal fluoroalkylsilane by a terminal fluoroalkylsilane coupling agent represented by the following general formula (V). In this case, the terminal fluoroalkylsilane coupling is used. The terminal fluoroalkyl modification with the agent is preferably performed by a hydrothermal method or microwave irradiation under the same conditions as the terminal (meth) acryl modification with the terminal (meth) acrylsilane coupling agent described above.

（上記一般式（Ｖ）中、Ｒ^３１〜Ｒ^３３は各々独立に、水素原子又は炭素数１〜４のアルキル基を表し、ｙａは１〜８の整数を表し、ｙｂは１〜３の整数を表す。）

(In said general formula (V), R < ³¹ > -R < ³³ > represents a hydrogen atom or a C1-C4 alkyl group each independently, ya represents the integer of 1-8, yb is the integer of 1-3. Represents.)

Examples of the terminal fluoroalkylsilane coupling agent include C ₈ F ₁₇ — (CH ₂ ) ₂ —Si— (OCH ₃ ) ₃ and C ₆ F ₁₃ — (CH ₂ ) ₂ —Si— (OCH ₃ ) _3. These may be used, and these may be used alone or in combination of two or more.

  By chemically modifying the surface of the porous silica using such a terminal fluoroalkylsilane coupling agent, the antifouling property of the formed low refractive index layer can be enhanced.

  The low refractive index layer of the present invention is formed by curing the binder component described above by irradiating with ultraviolet rays in the presence of a photopolymerization initiator. Examples of the photopolymerization initiator include Ciba Specialty. -1 type (s) or 2 or more types, such as Irgacure 184,819,651,1173,907 by a chemicals company, can be used, and it is preferable that the compounding quantity shall be 3-10 phr with respect to a binder component. When the blending amount of the photopolymerization initiator is less than this range, sufficient crosslinking and curing cannot be performed, and when the blending amount is large, the film strength of the low refractive index layer is lowered.

  The low refractive index layer according to the present invention comprises a composition obtained by mixing porous silica, a polyfunctional (meth) acrylic compound as a binder component, and a photopolymerization initiator at a predetermined ratio. It is formed by coating on the refractive index hard coat layer and curing by irradiating ultraviolet rays in an atmosphere having an oxygen concentration of 0 to 10000 ppm. Here, the oxygen concentration in the ultraviolet irradiation atmosphere exceeds 1000 ppm. Since the scratch resistance is greatly reduced, it is set to 1000 ppm or less, preferably 200 ppm or less.

  The thickness of such a low refractive index layer is preferably 85 to 110 nm.

  In the present invention, the hard coat layer 3, the transparent conductive layer 4, the light absorbing layer 5, the low refractive index layer 6 or the hard coat layer, the conductive light absorbing layer, and the base film 1 on which the easy adhesion layer 2 is formed. In order to form the low refractive index layer, it is preferable to apply an uncured resin composition (mixed with the above fine particles if necessary) and then irradiate with ultraviolet rays. In this case, each layer may be applied and cured one layer at a time, or after three or two layers are applied, they may be cured together.

  Specific examples of the coating method include a method in which a coating solution in which a binder component or the like is made into a solution with a solvent such as toluene is coated with a gravure coater, and then dried and then cured with ultraviolet rays. This wet coating method has the advantage that the film can be formed uniformly at high speed at low cost. Curing by irradiating with ultraviolet rays after this coating has the effect of improving adhesion and increasing the hardness of the film, and enables continuous production of an antireflection film without the need for heating.

  By applying such an antireflection film of the present invention to a PDP, a liquid crystal plate of an OA device, or a front filter of a CRT, good light transmission and durability can be secured.

  Hereinafter, the present invention will be described more specifically with reference to examples, comparative examples, and experimental examples.

Examples 1-4, Comparative Examples 1-3
Each layer was applied by the following procedure, and all layers were cured by irradiating with 800 mJ / cm ² of ultraviolet rays at an oxygen concentration of 150 ppm.

  First, on a TAC film having a thickness of 50 μm (an “TAC film” PET film manufactured by Fuji Film Co., Ltd. having an easy-adhesion layer having a refractive index of 1.57 and a film thickness of about 85 nm), a hard coat (“JSR” Z7503 ") was applied. The formed hard coat layer has a thickness of 8 μm and a pencil hardness of 3H. Next, a composition for forming a transparent conductive layer (“Ei-3” manufactured by Dainippon Paint Co., Ltd.) containing ITO fine particles, urethane acrylate and a photopolymerization initiator was applied. The formed transparent conductive layer has a thickness of about 0.35λ and a refractive index of 1.68.

  Next, as a composition for forming a light absorption layer, carbon black and titanium black having a median particle diameter of 90 nm (TiN is a main component, median particle diameter 60 nm), pentaerythritol tetraacrylate as a binder, and Ciba Specialty as a photopolymerization initiator A mixture of Irgacure 184 and 819 manufactured by Chemicals was applied. The photoinitiator was 5 phr with respect to pentaerythritol tetraacrylate. The light absorption layer changed the attenuation coefficient by changing the ratio of the fine particle mixture of carbon black and titanium black and the binder to form a light absorption layer having the refractive index, attenuation coefficient, and film thickness shown in Table 1. . The light absorption layer has a maximum attenuation coefficient of 0.35.

  Furthermore, the low refractive index layer film-forming composition having the combination and formulation shown in Table 1 was applied to form a low refractive index layer having a refractive index and a film thickness shown in Table 1.

  In Examples 1 to 4, porous silica having an average particle diameter of 60 nm and a refractive index n of about 1.30 was used. In Comparative Examples 1 to 3, silica fine particles (“IPA-ST” (particle size: 10 to 20 nm) manufactured by Nissan Chemical Industries, Ltd.) having no pores were used as silica. Moreover, the polyfunctional acryl of the binder used in Examples 1-4 is dipentaerythritol hexaacrylate, and the acryl used in Comparative Examples 1-3 is pentaerythritol tetraacrylate. As a photopolymerization initiator, Irgacure 184 was added to the binder in an amount of 5 phr.

  The refractive index of the low refractive index layer was changed by changing the blending ratio of the binder and fine particles as shown in Table 1.

  About the antireflection film obtained in this way, a black vinyl tape is pasted on the back surface (the surface not coated), the minimum reflectance with a spectrophotometer "U-4000" manufactured by Hitachi, Ltd., the reflectance at 400 nm, The transmittance at a wavelength of 550 nm was measured, and the results are shown in Table 1.

In addition, the antireflection film (low refractive index layer surface) is rubbed back and forth with a plastic eraser under a load of 4.9 × 10 ⁴ N / m ² , and if the film breaks, the reflection color changes. Accordingly, the number of reciprocations until this color changes was determined as the number of erase rubbers, and the scratch resistance was examined. The results are shown in Table 1. The target properties of this light absorption type antireflection film are as follows: the minimum reflectance is 0.5% or less, the reflectance is 2% or less at a wavelength of 400 nm, the transmittance is 70% or less at a wavelength of 550 nm, and the number of erase rubber is 100 times or more. is there.

  From Table 1, the following is clear.

  That is, Comparative Examples 1 to 3 show various performances when a low refractive index layer having a refractive index of 1.495 is used, but the transmittance exceeds 70% under the condition that the anti-rubber resistance is 100 times or more. In this case, the thickness of the light absorption layer must be reduced. If the absorption layer is made thinner as the transmittance exceeds 70%, the minimum reflectance will exceed 0.5%.

  On the other hand, in Examples 1 to 4 using porous silica and strong acrylic resin for the low refractive index layer, it is possible to produce a low refractive index layer having very good erase rubber resistance and a low refractive index. It was. For this reason, even if the film thickness of the light absorption layer is reduced and the attenuation coefficient of the light absorption layer is lowered, the minimum reflectance is maintained at 0.5% or less, and the minimum reflectance is 0.5% or less. In addition, an antireflection film having a transmittance exceeding 80% can be produced.

  In addition, all of the antireflection films prepared with this film configuration had a reflectance of 2 nm or less at a reflectance of a wavelength of 400 nm.

<Experimental example>
Below the aforementioned prescribed thickness and refractive index of the adhesion layer _{(n b + n HC) /} 2 -0.03 ≦ n a ≦ (n b + n HC) / 2 +0.03
as well as
(550/4) × (1 / n _a ) −10 nm ≦ T ≦ (550/4) × (1 / n _a ) +10 nm
An experimental example showing the basis of the above will be given.

  When the antireflection film is not provided with a hard coat layer, the scratch resistance and pencil height are lowered, and the film is easily damaged. Therefore, the hard coat layer is generally formed. The most common configuration is PET film / hard coat layer / high refractive index layer / low refractive index layer.

  In order to increase hardness, the hard coat layer is usually formed by blending a mixture of polyfunctional acrylic monomers or oligomers with silica fine particles modified with acrylic. The general refractive index of acrylic monomers and oligomers in the hard coat layer is Since the refractive index of silica fine particles is about 1.49 to 1.55 and about 1.47, the refractive index of the hard coat layer is about 1.49 to 1.55. On the other hand, the refractive index of the PET film is about 1.65, and the refractive index difference with the hard coat layer is large.

  Thus, when a hard coat layer is formed on a substrate film having a very different refractive index, a specific spectrum is generated, and the minimum reflectance is increased when an antireflection film is formed.

  A method of eliminating this and keeping the minimum reflectance low is a method of manipulating the film thickness and refractive index of the easy adhesion layer.

  First, an antireflection layer is formed with a hard coat layer / high refractive index layer / low refractive index layer as follows.

  The following experimental results show how much the minimum reflectance of the antireflection layer varies depending on the film thickness and refractive index of the easy adhesion layer when the antireflection layer is applied.

  In the following, an experimental example suitable for the present invention is shown as “Experimental example A”, and an experimental example corresponding to a comparative example is shown as “Experimental example B”.

Incidentally, the refractive index _{n b} is 1.65 of the base film, since the refractive index _{n HC} of the hard coat layer is _1.50, a _{(n b + n HC) /2≒1.58} .

  The reflection spectrum of each experimental example is shown in FIGS. 5 to 19 and the minimum reflectance is shown in Table 3.

  In both Experimental Example B-1 in which the PET film does not have an easy-adhesion layer and Experimental Example B-2 in which a normal easy-adhesion layer (refractive index 1.55, film thickness 20 nm) is provided, the reflectance is 0.35 to 0 It was high at 45%.

In Experimental Examples B-3 to B-5 and Experimental Examples A-1 to A-3, the optical film thickness of the easy-adhesion layer is accurately set to 1 / 4λ (0.25λ) with respect to light of 550 nm. The refractive index of the layer is changed. When the optical film thickness is 0.25λ, the film thickness of the easy adhesion layer accurately satisfies (550/4) × (1 / n _a ).

The refractive index of easy adhesion was changed to 1.54, 1.56, 1.58, 1.60, 1.62. From the reflection spectrum of each experimental example and the minimum reflectance at that time, the minimum reflectance decreases when the refractive index of the easy-adhesion layer approaches (n _b + n _HC ) / 2, and in particular, (n _b + n _HC ) / When 2 ± 0.02, a very high antireflection effect was observed. However, there was a tendency for the minimum reflectance to increase as the refractive index of the easy-adhesion layer moves away from (n _b + n _HC ) / 2.

Experimental Example B-3... N = 1.54d = (550/4) × (1 / n _a )
Experimental Example A-1... N = 1.56d = (550/4) × (1 / n _a )
Experimental Example A-2... N = 1.58d = (550/4) × (1 / n _a )
Experimental Example A-3... N = 1.60d = (550/4) × (1 / n _a )
Experimental Example B-4... N = 1.62d = (550/4) × (1 / n _a )
Experimental Example B-5 ··· n = 1.64d = (550/4) × (1 / n a)

Experimental Example B-6~B-9 and Example A-5, A-6, the influence of the thickness of the adhesive layer, i.e., the thickness of the adhesive layer is _{(550/4) × (1 / n} a ) Is shown.

The refractive index of the easy-adhesion layer is (n _b + n _HC ) / 2, that is, exactly 1.58, and the reflection spectrum of each experimental example in which the film thickness of the easy-adhesion layer was changed, and the minimum reflectance at that time, The refractive index of the easy-adhesion layer is
(N _b + n _HC ) / 2 −0.03 ≦ n _a ≦ (n _b + n _HC ) / 2 +0.03
In the range of
(550/4) × (1 / n _a ) −10 nm ≦ T ≦ (550/4) × (1 / n _a ) +10 nm
It is clear that the minimum reflectivity decreases in the range of.

Experimental Example B-6 ·· n = 1.58d = (550/4) × (1 / n _a ) −30 [nm] (57 nm)
Experimental Example B-7 ·· n = 1.58d = (550/4) × (1 / n a) -20 [nm] (67nm)
Experimental Example A-4 .. n = 1.58d = (550/4) × (1 / n _a ) −10 [nm] (77 nm)
Experimental Example A-5 ·· n = 1.58d = (550/4) × (1 / n a) [nm] (87nm)
Experimental Example B-7..n = 1.58d = (550/4) × (1 / n _a ) +10 [nm] (97 nm)
Experimental Example B-8..n = 1.58d = (550/4) × (1 / n _a ) +20 [nm] (107 nm)
Experimental Example B-9..n = 1.58d = (550/4) × (1 / n _a ) +30 [nm] (117 nm)

  From these results, when a general hard coat layer (n = 1.50) is used, the easy-adhesion layer has a refractive index of about 1.58 and a film thickness in the range of 77 to 97 nm. It can be seen that the prevention characteristic is obtained. Moreover, it was confirmed by doing in this way that the reflective color nonuniformity like the mottled pattern by the refractive index difference of a hard-coat layer and a base film can also be eliminated simultaneously.

  Excellent anti-reflection performance, scratch resistance, chemical resistance, etc., excellent durability, low-cost continuous production, low reflectivity especially on the low wavelength side, sufficient transmission of blue light The light-absorbing antireflection film of the present invention, which has a low transmittance on the low wavelength side and a yellowish transmission color, can be used for various displays such as word processors, computers, CRTs, plasma televisions, liquid crystal displays, and organic ELs. Useful for display surfaces.

It is typical sectional drawing which shows the structure of a light absorption type antireflection film. It is a reflection spectrum figure of the conventional antireflection film. It is a reflection spectrum figure of the conventional antireflection film. It is a reflection spectrum figure of a light absorption type antireflection film. It is a graph which shows the reflection spectrum of Experimental example B-1. It is a graph which shows the reflection spectrum of Experimental example B-2. It is a graph which shows the reflection spectrum of Experimental example B-3. It is a graph which shows the reflection spectrum of Experimental example A-1. It is a graph which shows the reflection spectrum of Experimental example A-2. It is a graph which shows the reflection spectrum of Experimental example A-3. It is a graph which shows the reflection spectrum of Experimental example B-4. It is a graph which shows the reflection spectrum of Experimental example B-5. It is a graph which shows the reflection spectrum of Experimental example B-6. It is a graph which shows the reflection spectrum of Experimental example B-7. It is a graph which shows the reflection spectrum of Experimental example A-4. It is a graph which shows the reflection spectrum of Experimental example A-5. It is a graph which shows the reflection spectrum of Experimental example A-6. It is a graph which shows the reflection spectrum of Experimental example B-8. It is a graph which shows the reflection spectrum of Experimental example B-9.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Base film 2 Easy adhesion layer 3 Hard-coat layer 4 Transparent conductive layer 5 Light absorption layer 6 Low refractive index layer

Claims (11)

In the antireflection film formed by laminating a hard coat layer, a transparent conductive layer, a light absorption layer and a low refractive index layer in this order on the transparent substrate film,
The low refractive index layer is
Hollow silica fine particles (hereinafter referred to as “porous silica”);
A polyfunctional (meth) acrylic compound;
The coating film containing the photopolymerization initiator is cured by irradiating ultraviolet rays in an atmosphere having an oxygen concentration of 0 to 10,000 ppm,
An antireflection film having a minimum reflectance of 0.5% or less, a transmittance of 70% or more at a wavelength of 550 nm, and a reflectance of 2% or less at a wavelength of 400 nm. In the antireflection film formed by laminating a hard coat layer, a conductive light absorption layer and a low refractive index layer in this order on the transparent substrate film,
The low refractive index layer is
Hollow silica fine particles (hereinafter referred to as “porous silica”);
A polyfunctional (meth) acrylic compound;
The coating film containing the photopolymerization initiator is cured by irradiating ultraviolet rays in an atmosphere having an oxygen concentration of 0 to 10,000 ppm,
An antireflection film having a minimum reflectance of 0.5% or less, a transmittance of 70% or more at a wavelength of 550 nm, and a reflectance of 2% or less at a wavelength of 400 nm. The antireflection film according to claim 1 or 2, wherein an easy adhesion layer is provided on the transparent base film, and a hard coat layer is provided on the easy adhesion layer,
The refractive index of the hard coat layer is 1.48 to 1.55,
The refractive index of the easy adhesion layer n _a, the refractive index n _b of the transparent substrate _film, and the refractive index of the hard coat layer and n _HC,
(N _b + n _HC ) / 2 −0.03 ≦ n _a ≦ (n _b + n _HC ) / 2 +0.03
The film thickness T of the easy adhesion layer is
(550/4) × (1 / n _a ) −10 nm ≦ T ≦ (550/4) × (1 / n _a ) +10 nm
An antireflection film characterized by being in the range.   4. The antireflection film according to claim 3, wherein the easy-adhesion layer is formed on the transparent base film when the transparent base film is formed. 5. The polyfunctional (meth) acrylic compound according to claim 1, wherein the polyfunctional (meth) acrylic compound is a hexafunctional (meth) acrylic compound represented by the following general formula (I) and / or the following general formula (II): An antireflection film comprising a tetrafunctional (meth) acrylic compound represented by the formula:

(In the general formula (I), A ^{1 to} A ⁶ each independently represents an acryloyl group, a methacryloyl group, an α-fluoroacryloyl group, or a trifluoromethacryloyl group,
n, m, o, p, q and r each independently represent an integer of 0 to 2;
R ^{1 to} R ⁶ each independently represents an alkylene group having 1 to 3 carbon atoms, or a fluoroalkylene group having 1 to 3 carbon atoms in which one or more hydrogen atoms are substituted with fluorine atoms. )

(In the general formula (II), A ^{11 to} A ¹⁴ each independently represents an acryloyl group, a methacryloyl group, an α-fluoroacryloyl group, or a trifluoromethacryloyl group,
s, t, u, v each independently represents an integer of 0-2,
R ^{11 to} R ¹⁴ each independently represents an alkylene group having 1 to 3 carbon atoms or a fluoroalkylene group having 1 to 3 carbon atoms in which one or more hydrogen atoms are substituted with fluorine atoms. ) 6. The porous silica according to claim 1, wherein the porous silica is reacted with a terminal (meth) acrylsilane coupling agent represented by the following general formula (IV) and a hydrothermal reaction at 100 to 150 ° C. An antireflection film characterized in that it is a (meth) acryl-modified porous silica whose surface is terminally (meth) acryl-modified by reaction under wave irradiation.

(In the general formula (IV), R ²¹ represents a hydrogen atom, a fluorine atom or a methyl group,
R ²² represents an alkylene group having 1 to 8 carbon atoms or a fluoroalkylene group having 1 to 8 carbon atoms in which one or more hydrogen atoms are substituted with fluorine atoms,
R ^{23 to} R ²⁵ each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. ) The porous silica according to any one of claims 1 to 5, wherein the porous silica is subjected to a terminal fluoroalkylsilane coupling agent represented by the following general formula (V) and a hydrothermal reaction at 100 to 150 ° C, or under microwave irradiation. An antireflection film, characterized in that the surface is fluoroalkyl-modified porous silica whose surface is fluoroalkyl-modified by reaction at

(In said general formula (V), R < ³¹ > -R < ³³ > represents a hydrogen atom or a C1-C4 alkyl group each independently, ya represents the integer of 1-8, yb is the integer of 1-3. Represents.) 8. The fine particle according to claim 1, wherein the transparent conductive layer is selected from the group consisting of ATO, ZnO, Sb ₂ O ₅ , SnO ₂ , ITO, and In ₂ O _3. Is a film cured with a (meth) acrylic binder resin, and the film thickness is 80 to 200 nm. The light absorption layer according to any one of claims 1, 3 to 8, wherein the light absorption layer includes carbon black fine particles and titanium nitride fine particles, and the complex refractive index of the light absorption layer is n + ik.
The value of n is 1.45 to 1.75
The value of k is 0.1 to 0.35
An antireflective film characterized by being The conductive light absorption layer according to any one of claims 2 to 7, wherein the conductive light absorption layer includes carbon black fine particles, and the complex refractive index of the conductive light absorption layer is n + ik.
The value of n is 1.45 to 1.75
The value of k is 0.1 to 0.35
An antireflective film characterized by being   The transparent substrate film according to any one of claims 1 to 10, wherein the transparent substrate film is a PET film, and the refractive index is 1.55 to 1.61 on the hard coat layer side of the PET film, and the film thickness is 75 to 75%. An antireflective film, wherein a 95 nm easy-adhesion layer is formed.

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