JP2009103734A - Anti-glare film, polarizing plate and image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an anti-glare film which prevents glittering, has excellent anti-glare property and does not cause the deterioration in display contrast, and to provide a polarizing plate and an image display device each using the anti-glare film. <P>SOLUTION: The anti-glare film 10 includes an anti-glare layer 1 having resin 1b and translucent particles 1a on a film substrate 3, wherein the average particle size of the translucent particles 1a is 0.2 to 1.0 μm, the thickness of the anti-glare layer 1 is ≤2.5 μm, the average ruggedness period (RSm value) of the anti-glare film 10 is ≤20 μm and the haze value is ≤10%. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an antiglare film, a polarizing plate using the same, and an image display device.

  Liquid crystal display devices (LCDs) are required to prevent reflection of external light and reflection of images. For this reason, the anti-glare film which prevents reflection of external light and the reflection of an image by arrange | positioning in the front surface of a display is proposed.

  For example, in order to prevent glare (image distortion or unevenness due to surface unevenness of the antiglare film), an antiglare film having a small average uneven period (RSm value) has been proposed (for example, Patent Document 1). And 2). However, these films necessarily have a high haze value as a whole, and may reduce the contrast of the liquid crystal display device. Generally, when the haze of the front film of a liquid crystal display device is high, the black luminance of the liquid crystal display device increases due to its light scattering property, and thus the contrast decreases.

In addition, an anti-glare film having a small average irregularity period (RSm value) and a low haze value has been proposed, and this film adheres a coating film before curing to a mold in which surface irregularities are preliminarily formed. It is made by the method of making it irradiate light from the transparent base material side, making it harden | cure, and peeling a coating film from a metal mold | die (for example, refer patent document 3). However, this manufacturing method is expected to have no continuous manufacturing suitability because dirt adheres to the mold and causes foreign matters.
Japanese Patent Laid-Open No. 9-127312 JP 2000-338309 A JP 2007-188792 A

  An object of the present invention is to provide an antiglare film that prevents glare, has excellent antiglare properties, and does not cause a decrease in display contrast, or a polarizing plate and an image display device using the same.

Usually, it has been difficult to design an antiglare film using small-sized translucent particles having an average particle size of 1 μm or less. This is because small particles are difficult to form surface irregularities because the particles are buried in the film thickness. In order to form surface irregularities using small particles, it is necessary to design the film thickness to be thin, but this will result in insufficient film hardness.
Moreover, even if the surface irregularities could be formed with small particles, it was difficult to obtain good antiglare properties because the individual particle projections on the film surface were too small.
On the other hand, the average uneven | corrugated period (RSm value) of an anti-glare film or an antireflection film is normally designed in the range of 50-100 micrometers. The reason for this is that when the average irregularity period (RSm value) is reduced, the number of particles forming the convex portions on the surface is large, and thus the whitening of the film reflected light is deteriorated.
Whitening is a phenomenon in which reflected light from a light source is reflected over the entire surface of the film and the film surface looks white, and is an undesirable phenomenon for a front film of an image display device.

However, as a result of intensive studies, the present inventors have reached the following new configuration.
That is, by using small-sized translucent particles having an average particle diameter of 1 μm or less and forming small surface unevenness having an average unevenness period (RSm value) of 20 μm or less, it is surprisingly good without whitening. It was found that antiglare properties can be obtained. In addition, since it is necessary to reduce the film thickness at this time, the coating amount of the light-transmitting particles, which is a light scattering factor of the film, is inevitably reduced, and it is easy to achieve a low haze value. It was found that there was almost no decrease. Further, the obtained surface irregularities had an unexpected advantage that glare can be prevented because the individual particle projections on the film surface are small.
If it is this structure, since it is the method of providing anti-glare property using translucent particle | grains, it is suitable also for continuous manufacture.
The present inventors have solved the above-mentioned problems from such a concept.

That is, the above object of the present invention has been achieved by the following means.
[1]
An antiglare film having an antiglare layer having a resin and translucent particles on a film substrate, wherein the average particle diameter of the translucent particles is 0.2 to 1.0 μm, and is antiglare. An antiglare film having a layer thickness of 2.5 μm or less, an average unevenness period (RSm value) of the antiglare film of 20.0 μm or less, and a haze value of 10% or less.
[2]
The antiglare film as described in [1] above, wherein the refractive index difference between the resin of the antiglare layer and the translucent particles is 0.03 or less.
[3]
The antiglare film according to the above [1] or [2], which has at least one hard coat layer between the film substrate and the antiglare layer.
[4]
Furthermore, the anti-glare film in any one of said [1]-[3] which has a low-refractive-index layer.
[5]
A polarizing plate having a polarizing film and protective films provided on both sides of the polarizing film, wherein at least one of the protective films is the antiglare film according to any one of [1] to [4]. Board.
[6]
The image display apparatus which has the anti-glare film in any one of said [1]-[4], or the polarizing plate as described in said [5].

  According to the present invention, it is possible to obtain an antiglare film that prevents glare, is excellent in antiglare properties, and has little reduction in display contrast.

Hereinafter, the antiglare film of the present invention will be described.
The antiglare film of the present invention has an antiglare layer having a resin and translucent particles on a film substrate.
In the antiglare film of the present invention, the translucent particles have a specific average particle diameter, the antiglare layer has a specific thickness, and the antiglare film has a specific average unevenness period (RSm value). ) And a haze value.

〔Basic structure〕
First, the basic structure of the antiglare film of the present invention will be described with reference to the drawings. Here, FIG. 1 is a cross-sectional view schematically showing a preferred embodiment of the antiglare film of the present invention.
An antiglare film 10 shown in FIG. 1 includes a film substrate 3, a hard coat layer 2 provided on the film substrate 3, and an antiglare layer 1 provided on the hard coat layer 2. .
And the glare-proof layer 1 consists of resin 1b and the translucent particle | grains 1a disperse | distributed in this resin 1b, and when the translucent particle | grains 1a exist, an unevenness | corrugation is formed in the surface of an anti-glare layer. As a result, the antiglare property is exhibited.

〔Layer structure〕
The antiglare film of the present invention is an antiglare film having at least one antiglare layer on a transparent film substrate (hereinafter also referred to as “support”). Further, depending on the purpose, other functional layers can be provided singly or in plural layers, and it is preferable to have at least one hard coat layer between the film base and the antiglare layer, and the upper layer side of the antiglare layer It is preferable to have a low refractive index layer for preventing reflection (when a low refractive index layer is provided, it functions as an antireflection film). In this specification, when it has a low-refractive-index layer, an anti-glare film may be called an antireflection film.

Examples of preferred layer configurations of the antiglare film and antireflection film of the present invention are shown below. In the following configuration, the film substrate refers to a support composed of a film.
-Film substrate / antiglare layer-Film substrate / hard coat layer / antiglare layer-Film substrate / hard coat layer / antiglare layer / low refractive index layer- Film substrate / hard coat layer / antiglare Dazzle layer / High refractive index layer / Low refractive index layerFilm substrate / Hard coat layer / Anti-glare layer / High refractive index layer / Medium 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. A method for forming each layer will be described later.
Each constituent layer will be described below.

[Low refractive index layer]
The low refractive index layer preferably provided in the present invention is located on the outermost surface side of the antireflection film and is the layer having the lowest refractive index among the layers of the antireflection film. By applying a low refractive index layer to obtain antireflection capability, the black brightness in the bright place is lowered, and the display contrast in the bright place is increased. Therefore, the display contrast in the antiglare film of the present invention is lowered. The effect that there is little is further improved.

  The refractive index of the low refractive index layer is preferably 1.20 to 1.50, more preferably 1.20 to 1.45, and most preferably 1.30 to 1.40. . Here, the refractive index of the layer can be quantitatively evaluated by directly measuring it with an Abbe refractometer or by measuring a spectral reflection spectrum or a spectral ellipsometry.

  The thickness of the low refractive index layer is preferably 10 nm to 500 nm, more preferably 20 nm to 200 nm, and most preferably 50 nm to 150 nm.

(Fluorine-containing compound having an ethylenically unsaturated group)
In the present invention, the low refractive index layer can be formed of a fluorine-containing compound having an ethylenically unsaturated group.
As the ethylenically unsaturated group in the fluorine-containing compound having an ethylenically unsaturated group used as a constituent material of the low refractive index layer, specifically, the terminal is vinyl group, allyl group, acrylolyl group, methacryloyl group, isopropenyl group. In other words, an acrylolyl group and a methacryloyl group are 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 specific examples of the fluorine-containing compound having two or more ethylenically unsaturated groups, conventionally known ones can be used without any particular limitation. For example, fluorine-containing polyfunctional (meta) described in JP-A-9-301925 can be used. ) Acrylic acid 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, JP2001 And fluorine-containing polyfunctional (meth) acrylic acid esters described in JP-A-72646.

  Further, the fluorine-containing compound having an ethylenically unsaturated group is preferably a polymer, and is a number average molecular weight in terms of polystyrene measured by gel permeation chromatography (hereinafter referred to as GPC) using tetrahydrofuran (hereinafter referred to as THF) as a solvent. Is preferably 1000 to 500,000. A number average molecular weight of 500,000 or less is preferred because the viscosity of the composition does not become too high and disadvantages such as difficulty in thinning do not occur.

  As the polymer as a fluorine-containing compound having an ethylenically unsaturated group that can be preferably used in the present invention, specifically, a polymer according to a known technique can be used, for example, JP-A-2005-89536, Examples thereof include ethylenically unsaturated group-containing fluorine-containing polymers described in JP-A-2005-290133 and JP-A-2006-36835.

  The amount of the fluorine-containing compound having an ethylenically unsaturated group is preferably 10 to 90% by mass, more preferably 20 to 80% by mass, and most preferably 30 to 70% by mass in the solid content of the low refractive index layer.

  The fluorine-containing compound having an ethylenically unsaturated group forming the low refractive index layer can be cured by the method described in (Curing method) in [Method for forming each layer] described later.

(Hollow silica fine particles)
In order to lower the refractive index of the low refractive index layer, it is preferable to use hollow silica fine particles in the low refractive index layer in addition to the fluorine-containing compound. The hollow silica fine particles preferably 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.

In the hollow silica fine particles, the radius r _i of the cavity inside the _particle, and the radius of the outer shell of the particle is r _o, the porosity x is calculated by the following equation.
^{_{x = (4πr i 3/3}} ) / (4πr o 3/3) × 100

The porosity x of the hollow silica fine particles 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 are difficult.
The refractive index of these hollow silica fine particles was measured with an Abbe refractometer {manufactured by Atago Co., Ltd.}.

  The amount of the hollow silica fine particles added is preferably 10 to 90% by mass, more preferably 20 to 80% by mass, and most preferably 30 to 70% by mass with respect to 100% by mass of the solid content of the low refractive index layer.

[Anti-glare layer]
The antiglare layer, which is an essential constituent layer of the present invention, is a layer provided below the low refractive index layer when a low refractive index layer is provided, and is the lowest when no low refractive index layer is provided. It is a layer provided as an upper layer.
The refractive index of the antiglare layer is preferably 1.45 to 1.60, and most preferably 1.45 to 1.55.

Moreover, in order to obtain the desired effect of the present invention of good antiglare property, the thickness of the antiglare layer needs to be 2.5 μm or less, and should be 0.1 to 2.2 μm. More preferably, it is most preferable that it is 0.2-2.0 micrometers.
If the thickness of the antiglare layer exceeds 2.5 μm, the translucent particles are buried in the film, and it becomes difficult to form surface irregularities, and good antiglare properties cannot be imparted.

  Next, constituent materials for the antiglare layer will be described. The anti-glare layer contains translucent particles and a resin as essential constituent materials.

(Translucent particles)
The average particle diameter of the translucent particles needs to be in the range of 0.2 to 1.0 μm, and most preferably in the range of 0.4 to 0.8 μm.
When the average particle size is less than 0.2 μm, it becomes difficult to form surface irregularities, and sufficient anti-glare properties cannot be expressed, and when it exceeds 1.0 μm, the average irregularity period (RSm value) is designed to be small. In this case, since the number of particles forming the convex portions on the surface is large, whitening of the reflected light of the film is deteriorated, and at the same time, glare cannot be prevented.
Specific examples of the translucent particles include resin particles such as acrylic particles, styrene particles, or acrylic-styrene particles; inorganic particles mainly containing silica, such as poly {(meth) acrylate} particles. Preferred examples include crosslinked resin particles such as crosslinked poly {(meth) acrylate} particles, polystyrene particles, crosslinked polystyrene particles, crosslinked poly (acryl-styrene) particles, melamine resin particles, and benzoguanamine resin particles.
Among them, translucent particles having a refractive index of 1.45 to 1.60 are preferable, and specifically, crosslinked polystyrene particles, crosslinked poly {(meth) acrylate} particles, and crosslinked poly (acryl-styrene) particles are preferable. Used.
Specific examples of translucent particles that are commercially available include MP series manufactured by Soken Chemical Co., Ltd., and SX-8742 series manufactured by JSR Corporation. Further, two or more kinds of translucent particles having different particle diameters may be used in combination.

  The refractive index of the translucent particles is preferably 1.45 to 1.60, more preferably 1.48 to 1.57 from the viewpoint of preventing display contrast from being lowered by designing the haze value to be small.

  The translucent particles are preferably blended in the formed antiglare layer so as to be contained in an amount of 10 to 60% by mass in the total solid content of the antiglare layer, and more preferably 15 to 50% by mass. %.

(resin)
In the present invention, a curable resin is preferably used as the resin that is an essential constituent material of the antiglare layer. Examples of the curable resin include a resin that is cured by the method described in (Curing Method) in [Method of forming each layer] described later. That is, even if it is a monomer in the coating material for forming the antiglare layer, it may be a monomer that exists as a resin in the finally formed antiglare layer. Examples of the monomer that forms such a curable resin include polyfunctional monomers having two or more (meth) acryloyl groups in one molecule.

  Polyfunctional monomers include 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, trimethylol Ethanetri (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaeth Thritol hexa (meth) acrylate, tri (2-hydroxyethyl) 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, tetradecane ethylene glycol di (meth) acrylate, 10-decanediol (Meth) acrylate, 3,8-bis (meth) acryloyloxymethyltricyclo [5.2.10] decane, hydrogenated bisphenol A di (meth) acrylate, 2,2-bis (4- (meth) acryloyloxy Diethoxyphenyl) Propane, 1,4-bis ((meth) acryloyloxymethyl) cyclohexane, hydroxypivalin sun ester neopentyl glycol di (meth) acrylate, bisphenol A diglycidyl ether di (meth) acrylate, epoxy modified bisphenol A di (meth) acrylate Etc. Only one type of polyfunctional monomer may be used, or two or more types may be used in combination.

The refractive index of the resin is preferably 1.45 to 1.60, more preferably 1.48 to 1.57 from the viewpoint of preventing display contrast from being lowered by designing the haze value to be small.
In this invention, 40-90 mass% is preferable in the total solid of an anti-glare layer, and, as for the addition amount of these curable resins, 50-85 mass% is the most preferable.
In addition to the above-described components, other components such as a polymerization initiator can be added to the antiglare layer in a range that does not impair the desired effect of the present invention.

In order to obtain a desired effect of the present invention called display contrast with a haze value of 10% or less, the difference in refractive index between the resin and the translucent particles in the antiglare layer is preferably 0.03 or less, Most preferably, it is 0.02 or less. Here, the refractive index may be high for either the resin or the translucent particles.
In the present invention, the antiglare layer preferably has an average irregularity period (RSm value) of 20.0 μm or less, and most preferably 14.0 μm or less, in order to prevent glare.

  The arithmetic average roughness (Ra) is preferably 0.03 to 0.20 μm. The arithmetic average roughness (Ra) can be measured by a commercially available stylus type surface roughness measuring instrument based on JIS standard B0601: 2001, and the average irregularity period (RSm) is based on JIS standard B0601: 2001, It can be measured with a commercially available stylus type surface roughness measuring instrument.

[Hard coat layer]
In the present invention, a hard coat layer is preferably provided between the film substrate and the antiglare layer, whereby the antiglare film of the present invention can be designed with high hardness.

  In the present invention, the refractive index of the hard coat layer is preferably from 1.45 to 1.60, more preferably from 1.48 to 1.57, and from the viewpoint of antireflection at the interface, antiglare properties Most preferably, it has the same refractive index as the layer.

  The thickness of the hard coat layer can be selected so that it is effective for imparting hard coat properties, and the curl of the antiglare film as a whole is in a practically acceptable range. 40 μm is preferable, more preferably 2 to 30 μm, and most preferably 2 to 15 μm.

(resin)
In the present invention, the hard coat layer contains a resin. A curable resin is preferably used as the resin. Examples of the curable resin include a resin that is cured by the method described in (Curing Method) in [Method of forming each layer] described later. That is, even if it is a monomer in the coating material for forming the hard coat layer, it may be any as long as it exists as a resin in the finally formed hard coat layer. Examples of the monomer that forms such a curable resin include polyfunctional monomers having two or more (meth) acryloyl groups in one molecule described in the description of the resin used in the antiglare layer. be able to.

In this invention, 80 mass% or more is preferable in the whole solid content of a hard-coat layer, and, as for the addition amount of the said resin, 90 mass% or more is more preferable.
In addition to the above-mentioned components, other components such as a polymerization initiator can be added to the hard coat layer as long as the desired effects of the present invention are not impaired.

[Film substrate]
As the film base material used in the present invention, those having excellent visible light transmittance (preferably light transmittance of 90% or more) and excellent transparency (preferably having a haze value of 1% or less) are preferably used. Specifically, for example, a polyester polymer such as polyethylene terephthalate and polyethylene naphthalate; a cellulose polymer such as diacetyl cellulose and triacetyl cellulose; a polycarbonate polymer; a film made of a transparent polymer such as an acrylic polymer such as polymethyl methacrylate Is mentioned. Also, styrene polymers such as polystyrene and acrylonitrile / styrene copolymer; polyethylene, polypropylene, polyolefins having a cyclic or norbornene structure, olefin polymers such as ethylene / propylene copolymer; vinyl chloride polymers, nylon and aromatic polyamides Examples thereof include a film made of a transparent polymer such as an amide polymer. Furthermore, imide polymers, sulfone polymers, polyether sulfone polymers, polyether ether ketone polymers, polyphenylene sulfide polymers, vinyl alcohol polymers, vinylidene chloride polymers, vinyl butyral polymers, arylate polymers, polyoxymethylene Examples thereof include a film made of a transparent polymer such as a polymer, an epoxy polymer, and a blend of these polymers. In particular, those having a small optical birefringence are preferably used.

  When the antiglare film of the present invention is used as a protective film for a polarizing plate, the film substrate is preferably triacetyl cellulose (TAC), polycarbonate, acrylic polymer, polyolefin having a cyclic or norbornene structure, or the like. is there. The film substrate may be the polarizer itself. With such a configuration, the obtained polarizing plate does not require a protective film made of TAC or the like, and the structure of the polarizing plate can be simplified, so that the number of manufacturing steps can be reduced and the production efficiency can be improved. Further, the polarizing plate can be further thinned. Further, the antiglare film also serves as a cover plate that is mounted on the surface of the liquid crystal cell.

  The thickness of the film substrate can be appropriately determined, but is generally about 10 to 500 μm in consideration of workability such as strength and handleability, and thin layer properties. 20-300 micrometers is especially preferable, and 30-200 micrometers is more preferable.

  The refractive index of the film substrate is usually preferably from 1.45 to 1.55. Further, the difference in refractive index between the antiglare layer or hard coat layer and the film substrate is preferably 0.02 or less because interference unevenness due to light refraction at the interface can be reduced.

<High refractive index layer, medium refractive index layer>
In the film of the present invention, a medium refractive index layer and / or a high refractive index layer can be preferably provided in order to improve the antireflection property.
Hereinafter, in the present specification, “high”, “medium”, and “low” of the high refractive index layer, the middle refractive index layer, and the low refractive index layer represent the relative refractive index relationship between the layers. In terms of the relationship with the film substrate, the refractive index preferably satisfies the relationship of film substrate> low refractive index layer, high refractive index layer> support.
In the present invention, the medium refractive index layer is a layer having a refractive index higher than that of the antiglare layer and lower than that of the high refractive index layer. It is preferable to be provided in between.
In the present specification, the high refractive index layer, the middle refractive index layer, and the low refractive index layer may be collectively referred to as an antireflection layer.

  The high refractive index layer and medium refractive index layer used in the present invention preferably contain inorganic fine particles in order to adjust the refractive index and improve the coating property on the antiglare layer, and the dispersion in which inorganic particles are dispersed in a dispersion medium Preferably, a binder precursor (for example, a known ionizing radiation curable polyfunctional monomer or polyfunctional oligomer) necessary for matrix formation, a photopolymerization initiator, or the like is added to the liquid, and a high refractive index layer and medium refractive index are added. A coating composition for forming a refractive index layer, a coating composition for forming a high refractive index layer and a medium refractive index layer on a transparent support, and an ionizing radiation curable compound (for example, a polyfunctional monomer or a polyfunctional oligomer) Etc.) is preferably cured by a crosslinking reaction or a polymerization reaction.

  The binder precursor of the high refractive index layer and the middle refractive index layer is preferably added in an amount of 5 to 80% by mass based on the solid content of the coating composition of the layer.

  The content of the inorganic fine particles in the high refractive index layer and the medium refractive index layer is preferably 30 to 90% by mass, more preferably 40 to 80% by mass, particularly preferably the total solid content of the high refractive index layer. It is 50-75 mass%. Two or more kinds of inorganic particles may be used in combination in each layer.

Examples of the inorganic fine particles include oxides of at least one metal selected from silicon, zirconium, titanium, aluminum, indium, zinc, tin, and antimony. Specific examples include SiO ₂ , ZrO ₂ , TiO ₂ , and Al ₂ O. ₃ , In ₂ O ₃ , ZnO, SnO ₂ , Sb ₂ O ₃ , ITO, ATO and the like. That is, in the present invention, the high refractive index layer and the medium refractive index layer contain oxide fine particles of at least one metal selected from Si, Al, Ti, Zr, Sb, Zn, Sn, and In. Is preferred. In addition, as the inorganic fine particles, BaSO ₄ , CaCO ₃ , talc, kaolin, and the like can be used.
When forming a high refractive index layer or a medium refractive index layer, a cured product of a coating composition in which the inorganic fine particles having a high refractive index are dispersed together with the binder precursor, an initiator, and an organically substituted silicon compound in a solvent. Is preferably used.
As the inorganic fine particles in this case, ZrO ₂ and TiO _{2 are} particularly preferably used from the viewpoint of refractive index.

[Method for forming each layer]
(Application method)
Each layer of the antiglare film of the present invention can be formed by applying the composition for forming each layer by the following known coating method, but is not limited to this method.
Dip coating method, air knife coating method, curtain coating method, roller coating method, wire bar coating method, gravure coating method, extrusion coating method (die coating method) (see US Pat. No. 2,681,294), micro gravure coating method and the like. Among these, the micro gravure coating method and the die coating method are preferable.

  Here, the micro gravure coating method is a method in which a gravure roll having a diameter of about 10 to 100 mm, preferably about 20 to 50 mm and engraved with a gravure pattern is installed below the support (film substrate), and A position where the gravure roll is rotated in the reverse direction with respect to the transport direction of the support and the surplus coating liquid is scraped off from the surface of the gravure roll by a doctor blade so that the upper surface of the support is in a free state. The coating method is characterized in that the coating solution is transferred onto the lower surface of the support in the coating method. A roll-shaped transparent support can be continuously unwound, and at least one layer can be coated on one side of the unwound support by a microgravure coating method.

  As coating conditions by the micro gravure coating method, the number of lines of the gravure pattern imprinted on the gravure roll is preferably 50 to 800 lines / inch, and more preferably 100 to 300 lines / inch. The depth of the gravure pattern is preferably 1 to 600 μm, more preferably 5 to 200 μm. The rotation speed of the gravure roll is preferably 3 to 800 rpm, more preferably 5 to 200 rpm. The transport speed of the support is preferably 0.5 to 100 m / min, and more preferably 1 to 50 m / min.

In order to supply the antiglare film of the present invention with high productivity, an extrusion method (die coating method) is preferably used in a region where the wet coating amount is small (20 cc / m ² or less).

(Curing method)
In the present invention, the antiglare film having each layer coated and dried can be cured by heat and / or ultraviolet irradiation. Here, curing by ultraviolet irradiation 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 or synchrotron radiation. This refers to curing the film by irradiating the dried film with ultraviolet light using a light source such as light.

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 a low refractive index layer which is the outermost layer of the antiglare layer or the antireflection layer.

[Characteristics of antiglare film]
(Average unevenness period (RSm value))
The antiglare film of the present invention has an average irregularity period (RSm value) of 20.0 μm or less, and particularly preferably 14.0 μm or less, in order to prevent glare.

(Haze)
The haze value of the antiglare film of the present invention is 10% or less, more preferably 0% to 8%, and most preferably 0% to 6%. When the haze value exceeds 10%, the display contrast is remarkably lowered, which is not suitable for the use of the image display apparatus. In this invention, about a haze value, according to JIS-K7136, the total haze value of the obtained optical film is measured.
The anti-glare film in the prior art has prevented glare by using “blur” by scattering transmitted light. That is, it can be said that high glare prevention and good anti-glare properties are achieved by designing a high haze value, but at the same time sacrifices display contrast.
However, in the present invention, the average particle diameter of the above-mentioned translucent particles, the thickness of the above-mentioned antiglare layer, the above RSm value and the above haze value are all satisfied within the above ranges, respectively. In this case, effects such as good anti-glare properties, glare prevention, and display contrast reduction, which were difficult in the case of the display, can be obtained.
In addition, examples of the optimum configuration that satisfies all the above ranges include the following configurations.
Film substrate: Triacetyl cellulose (TAC) is used.
Anti-glare layer; Cross-linked poly (acryl-styrene) having a thickness of 2.5 μm or less, containing dipentaerythritol pentaacrylate and / or dipentaerythritol hexaacrylate as a resin, and having an average particle size of 0.2 to 1.0 μm Contains particles.
Hard coat layer: It has a thickness of 2.0 to 15.0 μm and contains dipentaerythritol pentaacrylate and / or dipentaerythritol hexaacrylate as a resin.
Low refractive index layer; having a thickness of 50 to 150 nm, containing fluorine-containing polyfunctional (meth) acrylic acid ester and hollow silica fine particles.

(Display contrast)
In the present invention, the display contrast refers to the display contrast in a bright place. The contrast ratio (brightness in white display / brightness in black display) measured in the bright place environment shown in the examples is calculated by the following formula. Value.
Display contrast = (contrast ratio of antiglare film or antireflection film) / (contrast ratio of simple transparent hard coat film) × 100
The display contrast is preferably 90 or more because the display quality of the LCD panel can be improved.
In order to satisfy such display contrast, it is necessary to set the haze value of the film to 10% or less. Further, a low refractive index layer is provided as the uppermost layer, and the luminance of the black display is reduced by the antireflection effect. It is preferable to obtain.

(Polarizer)
Next, the polarizing plate of the present invention will be described.
The polarizing plate of the present invention is a polarizing plate having a polarizing film and protective films provided on both sides of the polarizing film, wherein at least one protective film is the above-described antiglare film of the present invention. And
The polarizing plate is an essential component for liquid crystal panels and the like.

  The polarizing film is not particularly limited, and various types can be used. Examples of polarizing films include dichroic substances such as iodine and dichroic dyes on hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and ethylene / vinyl acetate copolymer partially saponified films. Examples thereof include polyene-based oriented films such as those obtained by adsorbing substances and uniaxially stretched, polyvinyl alcohol dehydrated products and polyvinyl chloride dehydrochlorinated products. Among these, the former is generally used, and the thickness is about 5 to 80 μm.

  At least one of the protective films provided on one side or both sides of the polarizing film is the above-described anti-glare film. When a film other than the antiglare film is used, the material forming the protective film is preferably a material excellent in transparency, mechanical strength, thermal stability, moisture shielding property, isotropy and the like. For example, polyester polymers such as polyethylene terephthalate and polyethylene naphthalate, cellulose polymers such as diacetyl cellulose and triacetyl cellulose, acrylic polymers such as polymethyl methacrylate, styrene polymers such as polystyrene and AS resin, polycarbonate polymers, etc. can give. In addition, polyethylene, polypropylene, polyolefins having a cyclo or norbornene structure, polyolefin polymers such as ethylene / propylene copolymers, sulfone polymers, polyether sulfone polymers, polyether ketone polymers, polyphenylene sulfide polymers, vinyl alcohols Polymers, vinylidene chloride polymers, vinyl butyral polymers, acrylate polymers, polyoxymethylene polymers, epoxy polymers, and the like can be used, and a protective film can be formed by using them alone or in combination. The transparent protective film can also be formed as a cured layer of an acrylic, urethane-based, acrylic-urethane-based, epoxy-based, or silicone-based thermoset or ultraviolet-cured resin.

  Although the thickness of a protective film is suitably determined, generally it is about 1-500 micrometers from points, such as workability | operativity, such as intensity | strength and a handleability, and thin layer property. 1-300 micrometers is especially preferable. Moreover, it is preferable that a protective film has as little coloring as possible. By using a protective film having a thickness fragrance retardation value (Rth) of −90 nm to +75 nm, the coloring (optical coloring) of the polarizing plate caused by the protective film can be almost eliminated.

  As the protective film, a cellulose-based polymer such as triacetyl cellulose is preferable from the viewpoint of polarization characteristics and durability. A triacetyl cellulose film is particularly preferable. In addition, when providing a protective film on both sides of a polarizing film, the protective film which consists of the same polymer material may be used for the front and back, and the protective film which consists of a different polymer material may be used. The polarizing film and the protective film are usually in close contact with each other through an aqueous adhesive or the like. Examples of the aqueous adhesive include isocyanate adhesives, polyvinyl alcohol adhesives, gelatin adhesives, vinyl latexes, aqueous polyurethanes, aqueous polyesters, and the like.

  The surface of the protective film where the polarizing film is not adhered may be subjected to a treatment for the purpose of hard coat layer, antireflection treatment, sticking prevention, diffusion or antiglare.

(Image display device)
Next, the image display apparatus of the present invention will be described.
The image display device of the present invention has the antiglare film of the present invention described above or the polarizing plate of the present invention described above. That is, the antiglare film of the present invention is preferably used as a surface film of a screen of an image display device such as a liquid crystal panel.
The liquid crystal panel used includes a VA mode in which rod-like liquid crystal molecules are aligned substantially vertically when no voltage is applied, and is horizontally aligned when a voltage is applied, and an MVA mode in which the multi-domain is formed, and a nematic The IPS mode in which the liquid crystal is switched by applying a horizontal electric field, and the OCB mode in which rod-like liquid crystalline molecules are aligned substantially symmetrically at the upper and lower portions of the liquid crystal cell are modes having a wide viewing angle. An antiglare film or an antireflection film can be preferably used.
Furthermore, the higher the resolution of the liquid crystal panel, the more preferably the antireflection film of the present invention can be used. In particular, the liquid crystal panel is preferably used for a high-resolution liquid crystal panel called full-spec high-definition having 1920 × 1080 or 1440 × 1080. Can be used.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further more concretely, this invention is not restrict | limited to these.

  The compounds used in this example are shown below.

(Fluorine-containing compounds)
A methacryl-modified fluorine-containing polymer (A-1) obtained according to the method described in Production Example 2 of JP-A-2006-36835 was used as the fluorine-containing compound.

(Dispersion of hollow silica fine particles)
Hollow silica fine particle sol (Isopropyl alcohol silica sol, average particle diameter 60 nm, shell thickness 10 nm, silica concentration 20 mass%, silica particle refractive index 1.31, change size according to Preparation Example 4 of JP 2002-79616 A And 30 g of acryloyloxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) and 1.5 g of diisopropoxyaluminum ethyl acetate were added and mixed, and 9 g of ion-exchanged water was added. 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 matter 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%.

(Curable resin)
Mixture “DPHA” {manufactured by Nippon Kayaku Co., Ltd.} of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate, refractive index of cured film 1.52.
(Photopolymerization initiator)
“Irgacure 184” {manufactured by Ciba Specialty Chemicals Co., Ltd.}.

(Translucent particles)
“MP series” {manufactured by Soken Chemical Co., Ltd.}, acrylic / styrene copolymer particles.

  The addition amount of all the raw materials is shown in the table, with the solid content of the addition amount expressed in mass%.

<Preparation of antiglare film>
Example 1
Samples (101) to (110) of the antiglare film having the constitution shown in Table 1 were produced.

(Preparation of coating solution)
[Hard coat layer]
A methyl isobutyl ketone solution in which 96% by mass of the curable resin “DPHA” and 4% by mass of the photopolymerization initiator “Irgacure 184” was dissolved was prepared as a coating solution for the hard coat layer. The solid content concentration of the hard coat layer coating solution was adjusted to 40% by mass. The total solid content of the hard coat layer was described as 100% by mass.

[Anti-glare layer]
According to Table 1, a methyl isobutyl ketone solution in which the curable resin “DPHA” and the photopolymerization initiator “Irgacure 184” were dissolved was prepared.
Furthermore, according to Table 1, translucent particles “MP Series” manufactured by Soken Chemical Co., Ltd. were added according to Table 1, to obtain an antiglare layer coating solution. The amount added at that time was expressed as a solid content. The solid content concentration of the coating solution for the antiglare layer was adjusted to 40% by mass.
In Table 1, the total solid content of the antiglare layer is shown as 100% by mass.

[Coating of anti-glare film]
As a film base material, a triacetyl cellulose film “TAC-TD80U” {manufactured by FUJIFILM Corporation, film thickness 80 μm} is unrolled in a roll form, and a coater having a throttle die is used. The liquid was directly extruded and applied. After coating at a transfer speed of 30 m / min, drying at 30 ° C. for 15 seconds and at 80 ° C. for 20 seconds, and then applying an “air-cooled metal halide lamp” {manufactured by Eye Graphics Co., Ltd.) of 160 W / cm under a nitrogen purge. It was used to irradiate ultraviolet rays with an irradiation amount of 90 mJ / cm ² , and the coating layer was cured and wound up. The dry film thickness of the hard coat layer was 5 μm.

Further, the antiglare layer coating solution was applied onto the hard coat layer using a coater having a throttle die. After coating at a transfer speed of 30 m / min, drying at 30 ° C. for 15 seconds and at 80 ° C. for 20 seconds, and then applying an “air-cooled metal halide lamp” {manufactured by Eye Graphics Co., Ltd.) of 160 W / cm under a nitrogen purge. The applied layer was cured by irradiating with an ultraviolet ray having an irradiation amount of 90 mJ / cm ² . Table 1 shows the dry film thickness of the antiglare layer.

The laminated film obtained as described above was irradiated with an “air-cooled metal halide lamp” {manufactured by Eye Graphics Co., Ltd.) of 240 W / cm in an atmosphere with an oxygen concentration of 0.1% by nitrogen purge. An antiglare film having a structure shown in Table 1 was produced by irradiating ultraviolet rays of 400 mJ / cm ² . In Table 1, the component ratio is described with the total solid content of each layer as 100% by mass. The produced anti-glare film was evaluated by the following evaluation method.

〔Evaluation methods〕
[Surface haze]
The total haze value of the obtained antireflection film was measured according to JIS-K7136.

[Evaluation of anti-glare properties]
The produced anti-glare film was affixed to a non-coated surface with an acrylic adhesive having a thickness of about 20 μm and a polarizing plate having a smooth surface (50 mm × 50 mm). On this polarizing plate sample, a bare fluorescent lamp (8000 cd / m ² ) without a louver was projected from an angle of 45 °, and the degree of blurring of the reflected image when observed from the −45 ° direction was evaluated according to the following criteria.
A: The most preferable level where the outline of the fluorescent lamp is not known at all.
○: A preferable level that allows the outline of the fluorescent lamp to be slightly understood.
Δ: The fluorescent lamp is blurred, but the outline is discernible and is not acceptable.
X: A bad level where the fluorescent lamp is hardly blurred.
▼: The outline of the fluorescent lamp is not known, but the film reflected light is whitened and is not preferable.

[Measurement of front contrast]
(1) The produced anti-glare film was bonded to a polarizing plate having a smooth surface (50 mm × 50 mm) by attaching an acrylic adhesive having a film thickness of about 20 μm to the non-coated surface.
(2) The polarizing plate on the viewing side of the 32-inch full high-definition liquid crystal television “LC-32GS10” {manufactured by Sharp Corporation} was peeled off and attached to the central portion of the polarizing plate with an antiglare film.
(3) The light receiver “SPECTRORADIOMETER CS1000A” {manufactured by Konica Minolta Co., Ltd.} is set in front of the mounted liquid crystal television in parallel, and the ring illumination “MHF-G150LR” {diameter 37 mm, Co., Ltd. "Moritex" was set at a height of 27 mm. The irradiation angle of the light irradiated on the liquid crystal television screen from the ring illumination light at this set position was set to 30 °.
(4) An illuminometer “ILLUMINANCE METER” {manufactured by Topcon Corporation} was used to adjust the illuminance to 1000 Lx.
(5) The image on the liquid crystal television screen was switched between black display and white display, and the luminance at the black display and the white display at the central portion of the polarizing plate were measured as black luminance and white luminance, respectively. The contrast ratio (white luminance / black luminance) was calculated based on the value.
(6) As a reference value, a hard coat film having a thickness of 4.0 μm composed of only the curable resin “DPHA” and the photopolymerization initiator “Irgacure 184” is used, and the contrast ratio is set to the above (1) to (5 ) And normalized the value as 100.

[Evaluation of glare]
With the produced antiglare film attached to the above-mentioned liquid crystal television, the state of glare on the screen when the liquid crystal television was fully G-displayed was sensory evaluated.
○: Level at which glare does not matter at all.
Δ: A level at which slight glare occurs but does not matter.
X: Level at which glare occurs strongly and becomes a problem.

  The evaluation results are shown in Table 1.

In Table 1, all of the antiglare films (103), (104), (105), and (107) are the films of the present invention, and the average particle diameter of the translucent particles is 0.2 to 1.0 μm. Yes, the film thickness of the antiglare layer is 2.5 μm or less, the average unevenness period (RSm value) is 20.0 μm or less, and the haze value is 10% or less.
The anti-glare film (101) for comparison had no anti-glare property because no particles were added and there was no surface irregularity.
Moreover, the anti-glare film for comparison (102) also had a light-transmitting particle size that fell below the lower limit of the range of the present invention, and was unable to obtain good anti-glare properties.
In the comparative antiglare film (106), only the average particle diameter of the translucent particles exceeded the upper limit of the range of the present invention, and the antiglare property and the glare were not allowed. In the prior art, if the coating amount of (106) the antiglare layer is increased and the film thickness is increased, the surface unevenness can be reduced, so that the antiglare property can be improved. However, both the RSm value and the haze value are present. Increasing out of the scope of the invention will still result in a glare that is unacceptable and display contrast worse.
The comparative antiglare film (108) was a thick film in which only the film thickness of the antiglare layer was outside the range of the present invention, and good antiglare properties could not be obtained with small-sized translucent particles.
The comparative anti-glare film (109) is obtained by reducing the coating amount of translucent particles from the film of (107), and only the RSm value is out of the scope of the present invention, and the desired anti-glare property cannot be achieved. .
On the other hand, the anti-glare film for comparison (110) was obtained by increasing the coating amount of translucent particles from the film of (107), and only the haze value was outside the scope of the present invention, and the display contrast was greatly deteriorated.

<Preparation of anti-glare film having low refractive index layer>
-Example 2-
[Preparation of coating solution for low refractive index layer]
As a fluoropolymer having an ethylenically unsaturated group, 59.0% by mass in terms of solid content of the methacryl-modified fluoropolymer, and 40.0% by mass in terms of solid content of the hollow silica fine particle dispersion, photopolymerization An initiator “Irgacure 184” 1.0% by mass was mixed to prepare a coating solution for a low refractive index layer using methyl ethyl ketone as a solvent. The solid content concentration of the coating solution was 5% by mass. The refractive index of the low refractive index layer after curing was 1.38.

[Coating method of coating solution for low refractive index layer]
Using the coater having a throttle die on the antiglare layer of the antiglare films (103), (104), (105), and (107) obtained in Example 1, the low refractive index layer The coating solution was applied, dried at 80 ° C. for 60 seconds, and purged with nitrogen, using an “air-cooled metal halide lamp” {manufactured by Eye Graphics Co., Ltd.) of 240 W / cm in an atmosphere with an oxygen concentration of 0.1% by volume. The antireflection film (203), (204), (205), (207) is an antiglare film on which a low refractive index layer having a thickness of 100 nm is formed by irradiating an ultraviolet ray with an irradiation amount of 400 mJ / cm ^2. Was made.

〔Evaluation methods〕
[Integral reflectance]
Using the spectrophotometer {manufactured by JASCO Corp.}, the back side of the produced antireflection film was treated with black ink after being sanded with sandpaper and the backside reflection was eliminated. In the wavelength region of 380 to 780 nm, 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.

  The antireflection films (203), (204), (205), and (207) have an integrated reflectance of 1.5 to 1.7%, and the black luminance in the bright room environment is reduced, and the front contrast. Improved.

It is sectional drawing which shows typically one preferable embodiment of the anti-glare film of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Anti-glare layer 2 Hard coat layer 3 Film base material 10 Anti-glare film

Claims (6)

  An antiglare film having an antiglare layer having a resin and translucent particles on a film substrate, wherein the average particle diameter of the translucent particles is 0.2 to 1.0 μm, and is antiglare. An antiglare film having a layer thickness of 2.5 μm or less, an average unevenness period (RSm value) of the antiglare film of 20.0 μm or less, and a haze value of 10% or less.   The anti-glare film according to claim 1, wherein a difference in refractive index between the resin of the anti-glare layer and the translucent particles is 0.03 or less.   The anti-glare film according to claim 1 or 2, wherein at least one hard coat layer is provided between the film substrate and the anti-glare layer.   Furthermore, the anti-glare film in any one of Claims 1-3 which has a low-refractive-index layer.   The polarizing plate which has a polarizing film and the protective film provided in the both sides of this polarizing film, Comprising: At least one protective film is a polarizing plate which is an anti-glare film in any one of Claims 1-4.   The image display apparatus which has an anti-glare film in any one of Claims 1-4, or the polarizing plate of Claim 5.

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