JP2008233656A - Antireflection film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an antireflection film with high chemical resistance, in which crosslinking of an interface adjacent to a high refractive index layer (especially, crosslinking of an interface between the adjacent low-refractive index layer and the high refractive index layer) is enhanced, physical strength such as contactness, abrasion resistance is raised and further more, the physical strength is not impaired, even when saponification processing is performed. <P>SOLUTION: The antireflection film is used, in which there is the high refractive index layer, containing metal alkoxide having an ethylenically unsaturated group on a transparent support, the content of Ti and/or Zr per gram for solid content of the high refractive index layer is at least 2.0 millimoles; furthermore, the low refractive index layer containing fluorine-containing compound, having silica fine particles and the ethylenically unsaturated group as major components, is formed on the high refractive index layer and which is cured through heat and UV irradiation. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an antireflection film.

Anti-reflective films are placed on the display surface in various image display devices such as liquid crystal display (LCD), plasma display panel (PDP), electroluminescence display (ELD), cathode ray tube display (CRT), etc. In addition to preventing a decrease in contrast due to reflection of external light and reflection of an image, high physical strength (such as scratch resistance) and transparency are required.
The principle of antireflection is to reduce the reflected light by utilizing the optical interference of thin films having different refractive indexes. For the antireflection film, a technique for producing a high refractive index layer and a low refractive index layer is important.

For example, as a method for producing a high refractive index layer, a technique of a high refractive index film using both sol-gel thermal curing of metal alkoxide and UV curing is disclosed (for example, see Patent Documents 1 to 3). However, in these patent documents, even if the strength of the high refractive index layer itself can be increased, the adhesion is not satisfactory. In addition, the high refractive index film formed by the sol-gel method in these patent documents is a sol-gel that is a hydrolyzed polycondensate of metal alkoxide by saponification treatment of a high alkaline solution performed when an antireflection film is processed into a polarizing plate. The film may be hydrolyzed and the film strength may be deteriorated, so that the final polarizing plate form is not satisfactory in scratch resistance and adhesion.
In addition, the antireflection film according to the prior art is not satisfactory because uneven color of reflected light, which is presumed to be due to in-plane film thickness non-uniformity, easily occurs on the coated surface.
Japanese Patent No. 3675293 JP 2001-31871 A JP 2001-164119 A

The object of the present invention is to strengthen the cross-linking of the interface adjacent to the high refractive index layer (especially the cross-linking of the interface between the adjacent low refractive index layer and high refractive index layer) and improve physical strength such as adhesion and scratch resistance. In addition, the present invention provides an antireflection film having high chemical resistance that does not impair its physical strength even when saponification is performed.
Another object of the present invention is to provide an antireflection film having a low reflectance and less color unevenness of reflected light.

As a result of intensive studies, the present inventors have made a high refractive index layer containing a metal alkoxide having an ethylenically unsaturated group and Ti and / or Zr (a sol-gel component thereof) as a lower layer, silica fine particles and ethylenically unsaturated groups. The present inventors have found that the above-mentioned problems can be solved by a combination of a low refractive index layer mainly composed of a fluorine-containing compound having an upper layer and completed the present invention having the following constitution.
First, when the present inventors applied multiple layers of a high refractive index layer containing a large amount of Ti and / or Zr (a sol-gel component thereof) and a low refractive index layer containing silica fine particles and a fluorine-containing compound as main components, We found the surprising fact that no unevenness in the color of reflected light occurs because there is no soaking due to the intermingling of the layers and the thickness uniformity of the thin film is high. Although the cause is not clear, this is a phenomenon that occurs only when thin films are stacked.
Furthermore, the present inventors have found that when the high refractive index layer contains a metal alkoxide having an ethylenically unsaturated group and the low refractive index layer contains a fluorine-containing compound having an ethylenically unsaturated group, the upper layer is cured by ultraviolet curing. We found that the lower layer has strong interface bonding.
At this time, since there is a fluorine-containing compound in the upper layer, there is little permeation of alkaline water into the film even in high alkali solution treatment (saponification treatment), and the hydrolysis polycondensation part of the metal alkoxide in the high refractive index layer is hydrolyzed. I found it difficult to receive. Considering these matters, the present invention has been reached.
That is, the present invention has the following configuration.

(1) On the transparent support, there is a high refractive index layer containing a metal alkoxide having an ethylenically unsaturated group, and the content of Ti and / or Zr per gram solid content of the high refractive index layer is at least 2 A low refractive index layer containing as a main component a fine particle of silica and a fluorine-containing compound having an ethylenically unsaturated group on the high refractive index layer and cured by heat and ultraviolet irradiation. Prevention film.

(2) The antireflection film according to (1), wherein the metal species of the metal alkoxide having an ethylenically unsaturated group of the high refractive index layer is any one of Ti, Ta, Zr, In, and Zn.

(3) The antireflection film according to (1) or (2), wherein the fluorine-containing compound having an ethylenically unsaturated group of the low refractive index layer has two or more ethylenically unsaturated groups in one molecule.

(4) The antireflection film according to any one of (1) to (3), wherein the fluorine-containing compound having an ethylenically unsaturated group in the low refractive index layer is a polymer.

(5) The antireflection film according to any one of claims 1 to 4, wherein the silica fine particles are hollow silica fine particles.

(6) The antireflection film according to any one of (1) to (5), wherein the low refractive index layer has a refractive index of 1.20 to 1.40.

(7) The antireflection film according to any one of (1) to (6), wherein the refractive index of the high refractive index layer is 1.70 to 2.00.

(8) The antireflection film according to any one of (1) to (7), wherein the high refractive index layer further contains a polyfunctional monomer having two or more (meth) acryloyl groups in one molecule.

  In order to obtain an extremely low reflectance, the refractive index of a preferable thin film can be easily realized, and even when saponification is performed, an antireflection film having high film adhesion and excellent scratch resistance can be obtained.

Hereinafter, the antireflection film of the present invention will be described.
[Layer structure of optical film]
The antireflection film of the present invention has at least one high-refractive index layer and at least one low-refractive index layer on a transparent substrate (also referred to as a support), depending on the purpose. A functional layer can be provided alone or in multiple layers.
As a preferred embodiment, there can be mentioned an antireflection film laminated on the substrate in consideration of the refractive index, the film thickness, the number of layers, the layer order, etc. so that the reflectance is reduced by optical interference. The antireflection film is preferably configured by combining a high refractive index layer having a higher refractive index than that of the base material and a low refractive index layer having a lower refractive index than that of the base material. Examples of configurations include two layers of a high refractive index layer / low refractive index layer from the base material side, and three layers having different refractive indices, a medium refractive index layer (having a higher refractive index than the base material or hard coat layer). , A layer having a refractive index lower than that of a high refractive index layer) / a layer having a high refractive index / a layer having a low refractive index, and the like. Among them, in view of durability, optical characteristics, cost, productivity, etc., it is preferable to apply a medium refractive index layer / high refractive index layer / low refractive index layer in this order on a substrate having a hard coat layer. Examples include the configurations described in Kaihei 8-122504, 8-110401, 10-300902, JP-A 2002-243906, JP-A 2000-111706, and the like.
Other functions may be imparted to each layer, for example, an antifouling low refractive index layer or an antistatic high refractive index layer (eg, JP-A-10-206603, JP-A-2002). -243906 publication etc.) etc. are mentioned.

The example of the preferable layer structure of the film of the said aspect is shown below. In the following configuration, the base film refers to a support composed of a film.
-Base film / hard coat layer / high refractive index layer / low refractive index layer-Base film / anti-glare layer / high refractive index layer / low refractive index layer-Base film / moisture-proof layer / hard coat layer / high refraction Index layer / low refractive index layer / base film / moisture proof layer / antiglare layer / high refractive index layer / low refractive index layer / base film / hard coat layer / medium refractive index layer / high refractive index layer / low refractive index Layer / base film / antiglare layer / medium refractive index layer / high refractive index layer / low refractive index layer / moisture barrier layer / base film / hard coat layer / medium refractive index layer / high refractive index layer / low refractive index layer -Moisture-proof layer / base film / anti-glare layer / medium refractive index layer / high refractive index layer / low refractive index layer-base film / hard coat layer / conductive layer / medium refractive index layer / high refractive index layer / low Refractive index layer / base film / hard coat layer / conductive medium refractive index layer / high refractive index layer / low refractive index layer / moisture-proof layer / base film / hard coat layer Conductive intermediate refractive index layer / high refractive index layer / low refractive index layer

These layers can be formed by methods such as vapor deposition, atmospheric pressure plasma, and coating. From the viewpoint of productivity, it is preferably formed by coating.
Each constituent layer will be described below.

(Low refractive index layer)
In the present invention, the low refractive index layer is located on the outermost surface side of the antireflection film and has the lowest refractive index among the layers of the antireflection film, and contains a fluorine-containing compound having an ethylenically unsaturated group. To do.
Specifically, the ethylenically unsaturated group means that the terminal is a vinyl group, an allyl group, an acrylolyl group, a methacryloyl group, or an isopropenyl group, and an acrylolyl group or a methacryloyl group is particularly preferable.
Although one ethylenically unsaturated group may be present in one molecule, it is more preferable that the fluorine-containing compound having an ethylenically unsaturated group has two or more ethylenically unsaturated groups in one molecule.

  As a specific example of the fluorine-containing compound having two or more ethylenically unsaturated groups, a known technique can be used, for example, fluorine-containing polyfunctional (meth) acrylic acid described in JP-A-9-301925. Esters, fluorine-containing polyfunctional (meth) acrylic acid esters described in JP-A-10-182745, fluorine-containing polyfunctional (meth) acrylic acid esters described in JP-A-10-182746, JP-A-2001-72646 Mention may be made of the fluorine-containing polyfunctional (meth) acrylic acid esters described in the publication.

  Further, the fluorine-containing compound having an ethylenically unsaturated group is preferably a polymer, and the number average molecular weight in terms of polystyrene measured by tetrahydrofuran (hereinafter also referred to as THF) as a solvent by gel permeation chromatography (hereinafter also referred to as GPC). Is preferably 1000 to 500,000. When the number average molecular weight exceeds 500,000, the viscosity of the composition becomes high and it is difficult to make a thin film, which is not preferable.

  For the fluorine-containing polymer having an ethylenically unsaturated group, which is preferable in the present invention, specifically, a known technique can be used. For example, JP 2005-89536 A, JP 2005-290133 A, JP The ethylenically unsaturated group containing fluoropolymer described in 2006-36835 can be mentioned.

  The addition amount of the fluorine-containing compound having an ethylenically unsaturated group is preferably 10 to 100% by mass, more preferably 20 to 90% by mass, and more preferably 30 to 90% by mass with respect to 100% by mass of the solid content of the low refractive index layer. % Is most preferred.

In the present invention, the low refractive index layer contains silica fine particles, and the average particle diameter is preferably 1 nm to 100 nm. The silica fine particles may be solid particles, but it is preferable to use hollow silica fine particles in order to lower the refractive index. The hollow silica fine particles have a refractive index of 1.17 to 1.40, more preferably 1.17 to 1.35, and still more preferably 1.17 to 1.30. The refractive index here represents the refractive index of the whole particle, and does not represent the refractive index of only the outer shell silica forming the hollow silica fine particles. At this time, when the radius of the cavity in the particle is a and the radius of the particle outer shell is b, the porosity x is calculated by the following formula (VIII).
(Formula ^{VIII) x = (4πa 3/} 3) / (4πb 3/3) × 100
The porosity x is preferably 10 to 60%, more preferably 20 to 60%, and most preferably 30 to 60%. If the hollow silica fine particles are made to have a lower refractive index and a higher porosity, the thickness of the outer shell becomes thinner and the strength of the particles becomes weaker. Therefore, the low refractive index is less than 1.17 from the viewpoint of scratch resistance. Rate particles do not hold.
The refractive index of these hollow silica fine particles was measured with an Abbe refractometer (manufactured by Atago Co., Ltd.).

  The addition amount of these silica fine particles or hollow silica fine particles is preferably 10 to 80% by mass, more preferably 20 to 70% by mass, and most preferably 30 to 60% by mass with respect to 100% by mass of the solid content of the low refractive index layer. preferable.

In the present invention, the low refractive index layer contains, as main components, silica fine particles and a fluorine-containing compound having an ethylenically unsaturated group. When the total solid content of the low refractive index layer is 100% by mass, When the total solid content of the fluorine-containing compound having an ethylenically unsaturated group is 70% by mass or more, it can be said to be a main component. The total solid content of the silica fine particles and the fluorine-containing compound having an ethylenically unsaturated group is more preferably 80% by mass or more, and most preferably 90% by mass or more.
Moreover, it is preferable that ratio of solid content of a silica fine particle and the fluorine-containing compound which has an ethylenically unsaturated group is 3: 7-7: 3.

  The refractive index of the low refractive index layer is preferably 1.50 or less, more preferably 1.40 or less, and most preferably 1.20 to 1.40.

  The thickness of the low refractive index layer is preferably 10 nm to 500 nm, more preferably 20 nm to 300 nm, and most preferably 40 nm to 200 nm.

(High refractive index layer)
In the present invention, the high refractive index layer is an adjacent layer immediately below the low refractive index layer from the surface side of the antireflection film, and is a layer having a higher refractive index than the low refractive index layer described above, and an ethylenically unsaturated group. A metal alkoxide having
The metal alkoxide having an ethylenically unsaturated group may be added alone to the high refractive index layer, or a hydrolyzate may be added to the high refractive index layer.
Specifically, the ethylenically unsaturated group means that the terminal is a vinyl group, an allyl group, an acryloyl group, a methacryloyl group, or an isopropenyl group, and an acryloyl group or a methacryloyl group is particularly preferable.
There may be a plurality of ethylenically unsaturated groups in one molecule.

  The metal species of the metal alkoxide having an ethylenically unsaturated group is preferably a metal species in which the refractive index of the metal oxide when thermally cured is 2.0 or more, particularly any one of Ti, Ta, Zr, In, and Zn. It is preferable that Of these, Ti and Zr are most preferable.

  Specific examples of the metal alkoxide having an ethylenically unsaturated group include vinyltrimethoxytitanium, vinyltri (β-methoxy-ethoxy) titanium, divinyloxydimethoxytitanium, acryloyloxyethyltriethoxytitanium, γ-acryloyloxypropyltri ( n) Propoxy titanium, methacryloyloxypropyltri (n) propoxytitanium, di (γ-acryloyloxypropyl) di (n) propoxytitanium, acryloyloxydimethoxyethoxytitanium, methacryloyloxytriisopropoxytitanium, acryloyloxy (n) butoxytitanium 2- (acryloyloxy) ethoxytriisopropoxytitanium, vinyltrimethoxyzirconium, divinyloxydimethoxyzirconium, acryloyloxyethyltriethoxy Zirconium, γ-acryloyloxypropyltri (n) propoxyzirconium, γ-methacryloyloxypropyltri (n) propoxyzirconium, di (γ-acryloyloxypropyl) di (n) propoxyzirconium, acryloyloxydimethoxyethoxyzirconium, acryloyloxy ( n) Butoxyzirconium, vinyldimethoxythallium, vinyldi (β-methoxy-ethoxy) thallium, divinyloxymethoxythallium, acryloyloxyethyldiethoxythallium, γ-acryloyloxypropyldi (n) propoxytalium, γ-methacryloyloxypropyldi (N) propoxytalium, di (γ-acryloyloxypropyl) (n) propoxytalium, acryloyloxymethoxyethoxytali And acryloyloxy (n) butoxythallium.

  The addition amount of the metal alkoxide having an ethylenically unsaturated group is preferably 10 to 90% by mass, more preferably 15 to 85% by mass, more preferably 20 to 80% by mass with respect to 100% by mass of the solid content of the high refractive index layer. Is most preferred.

  The refractive index of the high refractive index layer is preferably 1.70 to 2.00, more preferably 1.75 to 1.95, and most preferably 1.80 to 1.90. .

  The thickness of the high refractive index layer is preferably 10 nm to 500 nm, more preferably 20 nm to 400 nm, and most preferably 40 nm to 300 nm.

  In the present invention, the content of Ti and / or Zr per gram of solid content in the high refractive index layer is at least 2.0 mmol, which is a sol-gel component in which the main component of the high refractive index layer is Ti or Zr. It is intended to be. When the content of Ti and / or Zr per gram of the solid content in the high refractive index layer is less than 2.0 mmol, the low refractive index layer and the high refractive index layer may permeate each other, resulting in uneven thickness. As a result, there arises a problem that unevenness of color occurs in the reflected light. In particular, the content of Ti and / or Zr per gram of the solid content of the high refractive index layer is more preferably 2.2 to 10.0 mmol, and most preferably 2.4 to 10.0 mmol. .

  The high refractive index layer preferably contains a tetraalkoxytitanium or tetraalkoxyzirconium monomer, oligomer or a hydrolyzate thereof as a sol-gel component of Ti or Zr. In these materials, after the membrane is dried, the film can be heated at a temperature of 90 to 200 ° C. to hydrolyze the alkoxide group and be condensed and cured.

Specific examples of the tetraalkoxy titanium include Ti (OCH ₃ ) ₄ , Ti (OC ₂ H ₅ ) ₄ , Ti (On-C ₃ H ₇ ) ₄ , Ti (Oi-C ₃ H ₇ ) _4. , Ti (On-C ₄ H ₉ ) ₄ , Ti (On-C ₃ H ₇ ) ₄ 2-10 mer, Ti (Oi-C ₃ H ₇ ) ₄ 2-10 And a di- to 10-mer of Ti (On-C ₄ H ₉ ) ₄ are preferred examples.

Specific examples of tetraalkoxyzirconium include Zr (OCH ₃ ) ₄ , Zr (OC ₂ H ₅ ) ₄ , Zr (On-C ₃ H ₇ ) ₄ , Zr (Oi-C ₃ H ₇ ) _4. , Zr (On-C ₄ H ₉ ) ₄ , Zr (On-C ₃ H ₇ ) ₄ 2 to 10 mer, Zr (OiC ₃ H ₇ ) ₄ 2 to 10 Preferred examples include Zr (On-C ₄ H ₉ ) ₄ dimer to 10-mer.
These can be used alone or in combination of two or more.
The amount of tetraalkoxytitanium or tetraalkoxyzirconium added is preferably 10 to 90% by mass, more preferably 20 to 80% by mass, and most preferably 20 to 70% by mass with respect to 100% by mass of the solid content of the high refractive index layer. preferable.

  The high refractive index layer may contain fine titanium oxide particles and fine zirconium oxide particles as necessary for refractive index adjustment. In that case, the Ti and Zr components of the titanium oxide fine particles and the zirconium oxide fine particles are added to the content of Ti and / or Zr per gram of the solid content of the high refractive index layer.

Further, the high refractive index layer preferably contains a polyfunctional monomer having two or more (meth) acryloyl groups in one molecule.
As polyfunctional monomers, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol (meth) acrylate, ethylene glycol di (meth) acrylate, triethylene glycol Di (meth) acrylate, tripropylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, 3-methylpentanediol di (meth) acrylate, diethylene glycol bis β- (meth) acryloyloxypropionate, trimethylolethane Tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, tri (2-H Roxyethyl) isocyanate di (meth) acrylate, pentaerythritol tetra (meth) acrylate, 2,3-bis (meth) acryloyloxyethyloxymethyl [2.2.1] heptane, poly 1,2-butadiene di (meth) acrylate 1,2-bis (meth) acryloyloxymethylhexane, nonaethylene glycol di (meth) acrylate, tetradecanethylene glycol di (meth) acrylate, 10-decanediol (meth) acrylate, 3,8-bis (meth) acryloyl Oxymethyltricyclo [5.2.10] decane, hydrogenated bisphenol A di (meth) acrylate, 2,2-bis (4- (meth) acryloyloxydiethoxyphenyl) propane, 1,4-bis ((meta ) Acryloyloxymethyl Examples thereof include cyclohexane, hydroxypivalin sun ester neopentyl glycol di (meth) acrylate, bisphenol A diglycidyl ether di (meth) acrylate, and epoxy-modified bisphenol A di (meth) acrylate. Only one type of polyfunctional monomer may be used, or two or more types may be used in combination.

  In the present invention, the addition amount of these polyfunctional monomers is preferably 1 to 50% by mass, more preferably 1 to 40% by mass, and 3 to 30% by mass with respect to 100% by mass of the solid content of the high refractive index layer. Most preferred.

(Medium refractive index layer)
In the present invention, in order to reduce the reflectance, it is preferable to provide a middle refractive index layer between the transparent support provided with the hard coat layer or the antiglare layer and the high refractive index layer. The refractive index of the medium refractive index layer is adjusted to be an intermediate value between the refractive index of the hard coat layer or the antiglare layer and the high refractive index layer, and the value is 1.55 to 1.80. preferable.

  The thickness of the medium refractive index layer is preferably 10 nm to 500 nm, more preferably 20 nm to 200 nm, and most preferably 40 nm to 200 nm.

The medium refractive index layer preferably contains a tetraalkoxytitanium or tetraalkoxyzirconium monomer, oligomer, or a hydrolyzate thereof, similarly to the high refractive index layer. Specific examples thereof are the same as those described for the high refractive index layer.
The amount of tetraalkoxytitanium or tetraalkoxyzirconium added is preferably 10 to 90 mass%, more preferably 10 to 70 mass%, and most preferably 10 to 50 mass% with respect to 100 mass% of the solid content of the medium refractive index layer. preferable.

Further, the medium refractive index layer preferably contains a polyfunctional monomer having two or more (meth) acryloyl groups in one molecule.
The polyfunctional monomer is the same as described for the high refractive index layer.
The addition amount of these polyfunctional monomers is preferably 1 to 90% by mass, more preferably 10 to 90% by mass, and most preferably 20 to 90% by mass with respect to 100% by mass of the solid content of the medium refractive index layer.

The present invention is characterized in that a low refractive index layer is formed on a high refractive index layer and cured by heat and ultraviolet irradiation.
The term “curing by heat” as used herein refers to curing the film by drying the film and then heating the film at a temperature of 90 to 200 ° C. for 1 to 60 minutes. In particular, heating is preferably performed at a temperature of 90 to 150 ° C. for 1 to 40 minutes, and more preferably at a temperature of 100 to 140 ° C. for 1 to 30 minutes.
In the case of curing by heat, each layer may be heated one by one, or may be heated after lamination. From the viewpoint of productivity, it is preferable to heat after forming the high refractive index layer.

Further, the curing by ultraviolet irradiation in the present invention means low pressure mercury lamp, medium pressure mercury lamp, high pressure mercury lamp, ultra high pressure mercury lamp, carbon arc lamp, metal halide lamp, xenon lamp, etc., ArF excimer laser, KrF excimer laser, excimer lamp. Alternatively, the film is cured by irradiating the dried film with ultraviolet rays using a light source such as synchrotron radiation.
The irradiation conditions vary depending on individual lamps, but the amount of light irradiated is preferably 20~10000mJ / cm ^2, more preferably from 100 to 2000 mJ / cm ^2, particularly preferably 400~2000mJ / cm ^2.
In the case of curing with ultraviolet rays, each layer may be irradiated one by one or after lamination. From the viewpoint of productivity, it is preferable to irradiate ultraviolet rays after forming the low refractive index layer.

The compounds used in this example are shown below.
Fluorine-containing compound having an ethylenically unsaturated group According to the method described in Example 3-3 of JP-A-9-301925, an ethylenically unsaturated group represented by (30) of JP-A-9-301925 is obtained. A fluorine-containing compound having the following structure having four in one molecule was obtained.
This compound was designated as a fluorine-containing compound A-1 having an ethylenically unsaturated group.

A methacryl-modified fluoropolymer obtained according to the method described in Production Example 2 of JP-A-2006-36835 was designated as A-2.
The acrylic modified fluoropolymer obtained according to the method described in Production Example 3 of JP-A-2006-36835 was designated as A-3.

Hollow silica fine particle dispersion Hollow silica fine particle sol (isopropyl alcohol silica sol, average particle diameter 60 nm, shell thickness 10 nm, silica concentration 20 mass%, refractive index of silica particles 1.31, according to Preparation Example 4 of JP-A-2002-79616) 500 g of acryloyloxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) and 1.5 g of diisopropoxyaluminum ethyl acetate were added to and mixed with 9 g of ion-exchanged water. . After reacting at 60 ° C. for 8 hours, the mixture was cooled to room temperature, and 1.8 g of acetylacetone was added. While adding cyclohexanone to 500 g of this dispersion so that the content of silica was almost constant, solvent substitution by vacuum distillation was performed. There was no generation of foreign matters in the dispersion, and the viscosity when the solid content concentration was adjusted to 20% by mass with cyclohexanone was 5 mPa · s at 25 ° C. When the residual amount of isopropyl alcohol in the obtained dispersion was analyzed by gas chromatography, it was 1.5%.

TEOS: Tetraethoxysilane hydrolyzate DPHA: Mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate [Nippon Kayaku Co., Ltd.]
Irg907: Polymerization initiator Irgacure 907 [Ciba Specialty Chemicals Co., Ltd.]
TBT: Tetra (n) butoxytitanium [Nippon Soda Co., Ltd.]

(Metal alkoxide having an ethylenically unsaturated group)
-Acrylyloxy (n) butoxy titanium It is set as compound B-1.
-Acrylyloxy (n) butoxyzirconium Compound B-2.

<Example 1>
Samples 101 to 105 of the antireflection film were produced with the constitutional requirements as shown in Table 1.

<Preparation of coating solution>
(Hard coat layer)
A methyl isobutyl ketone solution in which DPHA: 95% by mass and Irg907: 5% by mass were dissolved was prepared.
(High refractive index layer, low refractive index layer)
Coating solutions for the high refractive index layer and the low refractive index layer having the composition shown in Table 1 were prepared using methyl ethyl ketone as a solvent. The solid content concentration of the coating solution was 5%.

<Coating method of antireflection film>
A triacetyl cellulose film (TAC-TD80U, manufactured by Fuji Film Co., Ltd.) was unwound in a roll form, and using the coater having a throttle die, the aforementioned coating liquid for hard coat layer was directly extruded and applied. After applying at a transfer speed of 30 m / min, drying at 30 ° C. for 15 seconds and 90 ° C. for 20 seconds, and further using a 160 W / cm air-cooled metal halide lamp (made by Eye Graphics Co., Ltd.) under a nitrogen purge. The coating layer was cured by irradiating ultraviolet rays with an irradiation amount of 90 mJ / cm ² to form a hard coat layer having a thickness of 3.0 μm and wound up.

Further, the above-mentioned high refractive index layer coating solution was applied onto the above hard coat layer using a coater having a throttle die. It was applied at a transfer speed of 30 m / min, dried at 30 ° C. for 15 seconds and 90 ° C. for 20 seconds, then heat-treated at 100 ° C. for 5 minutes, and further air-cooled metal halide lamp of 160 W / cm under nitrogen purge (eye graphics) The coating layer was cured by irradiating with ultraviolet rays having an irradiation amount of 90 mJ / cm ² .
The thickness and refractive index of each layer are shown in Table 1.

On the high refractive index layer of the coated film obtained as described above, the above-mentioned coating solution for the low refractive index layer is applied using a coater having a throttle die, and dried: dried at 90 ° C. for 60 seconds. Then, an ultraviolet ray with an irradiation amount of 400 mJ / cm ^{2 was} irradiated using a 240 W / cm air-cooled metal halide lamp (manufactured by Eye Graphics Co., Ltd.) in an atmosphere with an oxygen concentration of 0.1% by nitrogen purge. Minute heating was performed to produce an antireflection film shown in Table 1.

Table 1 shows the component ratio, refractive index, and thickness of each layer of each sample.
In Table 1, the component ratio describes the component ratio in which the total solid content of each layer is 100% by mass.

Each antireflection film shown in Table 1 was evaluated by the following method.
The steel wool scratch resistance and adhesion were evaluated by a polarizing film processed film described later.

<Evaluation method>
[Integral reflectance]
The back side of the film was roughened with sandpaper, then treated with black ink, and the back side was removed, and the surface side was 380 to 780 nm using a spectrophotometer (manufactured by JASCO Corporation). In the region, the integrated spectral reflectance at an incident angle of 5 ° was measured. The arithmetic average value of the integrated reflectance of 450 to 650 nm was used for the result.

[Reflective color unevenness]
The antireflection film 1m ² of each sample was visually observed under a white fluorescent lamp, and the occurrence frequency of color unevenness of reflected light was classified and evaluated in the following three stages.
○: Reflected light color unevenness was not recognized at 1 m ² at all.
Δ: Reflected light color unevenness at one location per 1 m ² .
X: Reflected light color unevenness is 2 or more in 1 m ² .

[Saponification of optical film]
The back surface of each antireflection film sample was saponified under the following conditions.
Alkaline bath: 1.5 mol / dm ³ sodium hydroxide aqueous solution, 55 ° C.-120 seconds First water wash bath: tap water, 60 seconds Neutralization bath: 0.05 mol / dm ³ sulfuric acid, 30 ° C.-20 seconds Second water wash bath : Tap water, 60 seconds Drying: 120 ° C, 60 seconds [Preparation of polarizing plate with optical film]
A polarizing film was prepared by adsorbing iodine to a stretched polyvinyl alcohol film. A saponified antireflection film was attached to one side of the polarizing film using a polyvinyl alcohol adhesive so that the support (triacetylcellulose) side of the antireflection film was the polarizing film side. In this way, a polarizing plate was produced.

[Steel wool scratch resistance]
The surface of the antireflection film having the low refractive index layer was subjected to 50 reciprocations by applying a weight of 200 g / cm ² to steel wool, and the state of scratches generated at this time was observed and evaluated in the following five stages.
(Double-circle): The thing which did not scratch at all.
○: Slightly invisible scratches.
Δ: Scratches clearly visible.
X: Scratches clearly visible.
XX: The film peeled off.

[Adhesion]
The surface of the antireflective film having the low refractive index layer is cut with a cutter knife into a grid pattern with 11 vertical and 11 horizontal cuts, and a total of 100 square grids are engraved, made by Nitto Denko Corporation. A polyester adhesive tape (NO. 31B) was pressure-bonded and the adhesion test was repeated 5 times at the same place. The degree of peeling was evaluated according to the following four levels.
A: No peeling was observed in 100 squares.
○: Within 100 squares, peeling was observed within 2 squares.
(Triangle | delta): The thing by which peeling was recognized in 100 squares is a thing of 3-10cm.
X: A thing in which peeling was recognized in 100 squares exceeded 10 squares.

  The evaluation results according to the above evaluation method are shown in Table 2.

In Table 2, when samples 101, 102, and 103 having different constitutional requirements for the low refractive index layer are compared, only sample 101 of the present invention satisfies both scratch resistance and adhesion. In Comparative Example 102, since the outermost layer is a sol-gel film, the strength of both the low refractive index layer and the high refractive index layer is deteriorated due to the saponification treatment, and the scratch resistance is poor. In Comparative Example 103, the outermost layer uses DPHA as a binder, and since the chemical resistance of DPHA is low, it is presumed that film strength deterioration of the high refractive index layer is caused by saponification treatment. On the other hand, in the low refractive index layer containing the fluorine-containing compound having the ethylenically unsaturated group (Compound A-1) of the sample 101, the saponification treatment is performed by containing the fluorine-containing compound having the ethylenically unsaturated group. It is considered that the adverse effect of is not exerted on the high refractive index layer. Further, when the samples 101, 102, 103, and 105 are compared, only the present invention 101 has good reflected light color unevenness. It is presumed that this is because only the combination of the present invention does not permeate the interface between the low refractive index layer and the high refractive index layer, so that the thickness of each thin layer is kept uniform in the plane.
On the other hand, samples 101, 104, and 105 containing hollow silica fine particles and a fluorine-containing compound having an ethylenically unsaturated group (compound A-1) in the low refractive index layer and having different constitutional requirements for the high refractive index layer were compared. However, only the sample 101 of the present invention satisfies both scratch resistance and adhesion. In Comparative Example 104, the sol-gel component ratio of the high refractive index layer is too high, and the adhesion at the interface between the low refractive index layer and the high refractive index layer is poor. In Comparative Example 105, since there is no metal alkoxide having an ethylenically unsaturated group (Compound B-1) in the high refractive index layer, the adhesion at the interface between the low refractive index layer and the high refractive index layer is insufficient. That is, it can be seen that the metal alkoxide having an ethylenically unsaturated group (Compound B-1) is preferably contained in the high refractive index layer.
From these comparisons, it can be seen that the present invention is superior to the prior art.

<Example 2>
Samples 201 to 205 were prepared in the same manner as in Example 1 except that a medium refractive index layer was newly provided between the hard coat layer and the high refractive index layer of Example 1.
The coating solution for the medium refractive index layer was applied with methyl ethyl ketone as a solvent and a solid content concentration of 5%.
The component ratio, refractive index, and thickness of each layer of each sample are shown in Table 3.
In Table 3, the component ratio is described with the total solid content of each layer being 100% by mass.

The inventive products 201 to 205 were evaluated in the same manner as in Example 1.
The evaluation results are shown in Table 4.

  As can be seen from Table 4, when the fluorine-containing compound having an ethylenically unsaturated group is a polymer (compounds A-2 and A-3), both the steel wool scratch resistance, adhesion, and reflected light color unevenness are extremely high. Favorable results have been obtained. Moreover, since the low refractive index layer, the high refractive index layer, and the middle refractive index layer were formed with the optimal refractive index and the optimal thickness for each sample, the integrated reflectance showed a very low value.

Claims (8)

  There is a high refractive index layer containing a metal alkoxide having an ethylenically unsaturated group on the transparent support, and the content of Ti and / or Zr per gram of the solid content of the high refractive index layer is at least 2.0. An antireflection film formed by forming a low-refractive index layer containing as a main component a silica fine particle and a fluorine-containing compound having an ethylenically unsaturated group on the high-refractive index layer and being cured by heat and ultraviolet irradiation .   The antireflection film according to claim 1, wherein the metal species of the metal alkoxide having an ethylenically unsaturated group in the high refractive index layer is any one of Ti, Ta, Zr, In, and Zn.   The antireflection film according to claim 1 or 2, wherein the fluorine-containing compound having an ethylenically unsaturated group in the low refractive index layer has two or more ethylenically unsaturated groups in one molecule.   The antireflection film according to claim 1, wherein the fluorine-containing compound having an ethylenically unsaturated group in the low refractive index layer is a polymer.   The antireflection film according to claim 1, wherein the silica fine particles are hollow silica fine particles.   The antireflective film according to claim 1, wherein the low refractive index layer has a refractive index of 1.20 to 1.40.   The antireflective film according to claim 1, wherein the high refractive index layer has a refractive index of 1.70 to 2.00.   The antireflective film according to claim 1, wherein the high refractive index layer further contains a polyfunctional monomer having two or more (meth) acryloyl groups in one molecule.