JP2007072372A - Antireflection film, its manufacturing method, and image display apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a glare-proof antireflection film excellent in dust-proof effect (dust sticking prevention) and its manufacturing method and further to provide a polarizing plate and an image display apparatus, especially a liquid crystal display apparatus, using the glare-proof antireflection film excellent in the dust-proof effect. <P>SOLUTION: In the antireflection film, an uppermost layer C on a transparent supporting body A contains a fluorine-containing compound, a haze value resulting from surface scattering is 0.1 to 10% and friction-charged electrostatic potential is within ±500 V when being rubbed with cotton cloth at 30 mm/sec. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an antireflection film excellent in preventing dust adhesion, a method for producing an antireflection film having low frictional chargeability, and an image display device using the antireflection film.

In recent years, liquid crystal display devices (LCDs) have been increased in screen size, and liquid crystal display devices provided with antireflection films are increasing.
Antireflection films are not limited to liquid crystal display devices (LCDs), but are used in various image display devices such as plasma display panels (PDPs), electroluminescence displays (ELDs), and cathode ray tube display devices (CRTs). In order to prevent a decrease in contrast due to image reflection, it is arranged on the surface of the display. Therefore, the antireflection film is required to have high physical strength (such as scratch resistance), transparency, antifouling property, chemical resistance, and weather resistance (such as moisture and heat resistance). Furthermore, measures are required to prevent dust (such as dust) that reduces the visibility of the display from adhering to the surface of the antireflection film.
In addition, a technique of containing a fluorine compound in the uppermost layer for preventing reflection is known, but fluorine is negative in the charged column. Since dust fibers, especially cotton fibers, are positively charged, the film containing a fluorine compound on the surface has a drawback that dust tends to adhere.
Further, the antiglare film having surface scattering and internal scattering has a drawback that dust adhesion due to charging is easily noticeable.

As an antiglare antireflection film excellent in dust adhesion prevention, for example, Patent Document 1 discloses that the surface has irregularities, and vertical peeling measured at room temperature and normal humidity with respect to either triacetyl cellulose or polyethylene terephthalate. An antiglare antireflection film having a charge amount of −200 to +200 pc (picocoulomb) / cm ² and a surface resistance value of 1 × 10 ¹¹ Ω / □ or more is disclosed. Good dust wiping property As an antireflection film, Patent Document 2 discloses that in an antireflection film in which an antireflection layer is laminated on the surface of a hard coat layer provided on a transparent substrate, the antireflection layer has a refractive index of n _d ²⁰ ≦ 1. .49, at least two kinds of low refractive index materials, that is, (A) mainly composed of a polysiloxane structure and (B) mainly composed of a fluorine-containing material. Triboelectric charge amount generated when rubbed surface of the antireflection layer is 燥硬 monolayer with wool, antireflection film, which is a -1 to + 2KV is disclosed.

JP 2002-55206 A JP 2004-160736 A

  An object of the present invention is to provide an antiglare antireflection film excellent in dustproof property (dust adhesion preventing property) and a method for producing the same. Another object of the present invention is to provide an image display device using an antiglare antireflection film having excellent properties.

  According to the present invention, an antireflection film having the following constitution, a method for producing the antireflection film, and an image display device are provided, and the above object of the present invention is achieved.

[1]
The uppermost layer on the transparent support contains a fluorine-containing compound, has a haze value of 0.1% or more and 10% or less due to surface scattering, and has a frictional voltage of ± 500 V when rubbed with a cotton cloth at 30 mm / sec. An antireflection film characterized by being within.
[2]
The antireflection film as described in [1], wherein the haze value resulting from internal scattering is 5 to 30%.
[3]
A film containing a fluorine-containing compound in the uppermost layer on the transparent support is treated with an alkaline aqueous solution of 3 to 7 N at 40 to 80 ° C. for 2 to 5 minutes, so that the friction voltage is within ± 500 V. A method for producing an antireflective film.
[4]
An image display device using the antireflection film according to [1] or [2] on an outermost surface of a display.

  According to the present invention, not only the antiglare property and antireflection property, but also an antireflection film excellent in dustproof property (dust adhesion prevention property) can be obtained. Excellent visibility and dust resistance.

The basic structure of the antireflection film of the present invention is shown in FIG. The embodiment shown in FIG. 1 is an example of the antireflection film of the present invention. On the transparent support A such as a cellulose acylate film, for example, a hard coat layer B also serving as an antiglare layer, and an antireflection layer containing a fluorine-containing compound. C layer structure.
In the hard coat layer B that also serves as an antiglare layer, for example, antiglare particles are dispersed, and irregularities are formed on the surface of the layer B to scatter light on the surface and also scatter light on the inside to prevent the film. Dazzle (anti-glare) performance and the like can be imparted. The hard coat layer itself may also serve as the antiglare layer, but an antiglare layer may be provided on the hard coat layer.
On the transparent support A, for example, a layer B having a refractive index of about 1.57 to 2.00 and a low refractive index layer C containing a fluorine-containing compound having a refractive index of about 1.38 to 1.49. If present, the film can be provided with antireflection properties. In addition to the low refractive index layer C containing the uppermost fluorine-containing compound, the antireflection layer may have, for example, a high refractive index layer and a medium refractive index layer.
Further, layers other than the transparent support A, the hard coat layer B also serving as an antiglare layer, and the antireflection layer C may be provided as appropriate.

  The antireflection film of the present invention contains a fluorine-containing compound in the uppermost layer on the transparent support, has a haze value due to surface scattering of 0.1% or more and 10% or less, and was rubbed with a cotton cloth at 30 mm / sec. The frictional voltage at the time is within ± 500V.

  The antireflective film of the present invention is rubbed with a cotton cloth that is easily positively charged even though it contains a fluorine-containing compound that is easily negatively charged in the uppermost layer on a transparent support such as a cellulose acylate film. Is low (the frictional band voltage when rubbed at 30 mm / sec is within ± 500 V), and thus has excellent dust adhesion prevention properties. In order to make the frictional voltage within ± 500 V when the antireflection film containing the fluorine-containing compound in the uppermost layer is rubbed at 30 mm / sec with a cotton cloth in this way, for example, an alkaline aqueous solution of 3 to 7 N is used. The film can be treated at 40 to 80 ° C. for 2 to 5 minutes.

  In order to prevent dust adhesion, the friction band voltage when rubbing with a cotton cloth at 30 mm / sec is preferably within ± 500 V, more preferably within ± 300 V, and even more preferably within ± 100 V.

However, even if the frictional voltage when rubbing with a cotton cloth at 30 mm / sec is within ± 500 V, if the haze value due to surface scattering is less than 0.1% or more than 10%, Adhesion is conspicuous.
Therefore, the haze value resulting from surface scattering is preferably from 0.1% to 10%, more preferably from 0.5% to 9%, and even more preferably from 1% to 8%.

The method for measuring the frictional voltage is as follows.
The measurement sample is attached to a glass plate and left in advance in an environment of 25 ° C. and 55% RH for 2 hours or more. In the measurement, a cotton cloth was placed on the sample subjected to charge elimination at a pressure of 100 g / cm ² , and the charged voltage was monitored while only the sample was linearly reciprocated at 30 mm / sec. The charged voltage was the value measured at the 20th round-trip.

Moreover, the measuring method of the haze value (surface haze) resulting from surface scattering and the haze value (internal haze) resulting from internal scattering is as follows.
The total haze (H), internal haze (Hi), and surface haze (Hs) of the obtained film were measured by the following measurements.
[1] The total haze value (H) of the film obtained according to JIS-K7136 was measured.
[2] A few drops of silicone oil are added to the front and back surfaces of the obtained film on the low refractive index layer side, and sandwiched from the front and back using two 1 mm thick glass plates (micro slide glass product number S9111, made by MATSUNAMI) Then, the two glass plates and the obtained film are optically closely adhered, the haze is measured in a state where the surface haze is removed, and only silicone oil is sandwiched between the two glass plates separately measured. The value obtained by subtracting the measured haze was calculated as the internal haze (Hi) of the film.
[3] A value obtained by subtracting the internal haze (Hi) calculated in [2] from the total haze (H) measured in [1] was calculated as the surface haze (Hs) of the film.

  In order to impart antiglare properties to the layer B, for example, a transparent support described in JP-A No. 61-209154 is coated with a concavo-convex layer in which particles are added to a binder. No. 16851, a film having an uneven surface formed in advance and bonded to a coating layer on a transparent support to transfer the unevenness, directly on the transparent support or through another layer such as a hard coat layer And the like in which irregularities are formed by embossing. Among them, the method of forming irregularities by adding particles to a binder is preferable in that it can be produced easily and stably.

The antiglare layer is preferably composed of a binder and particles imparting antiglare properties (hereinafter also referred to as “antiglare particles”). The antiglare particles are not particularly limited as long as irregularities are formed on the surface of the antiglare layer. Moreover, in order to form an unevenness | corrugation effectively in the surface of an anti-glare layer, it is preferable that an average particle diameter is 0.5-10 micrometers, and it is more preferable that it is 1-7 micrometers. More preferably, it is 2-5 micrometers. For the antiglare layer, it is preferable to use antiglare particles in which particles having a particle size larger than one half of the film thickness account for 40 to 100% of the entire particles. As described above, the antiglare particles are provided for forming anti-glare properties by forming irregularities on the surface. Examples of the antiglare particles include polymethyl methacrylate resin, fluorine resin, vinylidene fluoride resin, silicone resin, epoxy resin, nylon resin, polystyrene resin, phenol resin, polyurethane resin, crosslinked acrylic resin, crosslinked polystyrene resin, melamine resin, Examples include resin particles such as benzoguanamine resin, or inorganic particles such as TiO ₂ , Al ₂ O ₃ , In ₂ O ₃ , ZnO, SnO ₂ , Sb ₂ O ₃ , ZrO ₂ , ITO, MgF ₂ , SiO ₂ , and aluminosilicate. It is done. The particles are preferably insoluble in water and organic solvents. The shape may be irregular or spherical. The anti-glare particles added to the anti-glare layer may be used in combination of two or more kinds of particles in order to control surface irregularities.

  If the refractive index difference between the antiglare particles and the binder forming the antiglare layer is less than 0.05, the contrast reduction due to scattered light, that is, the deterioration of whiteness can be prevented in the black display of the LCD. When the difference in refractive index is 0.05 or more, or when the scattering particles are used, whiteness is deteriorated, but glare caused by enlargement of pixels due to surface unevenness in a high-definition LCD can be prevented. Therefore, it is desirable that the refractive index design of the antiglare particles and the use of the scattering particles are properly used depending on the functions required for the LCD used.

  The refractive index of the antiglare layer is not described by one value. By adding scattering particles (anti-glare particles), the entire anti-glare layer becomes a non-refractive index layer whose refractive index is not defined by one value. Due to this non-uniform refractive index layer, the large amplitude in the wavelength dependence of reflectance caused by optical interference due to the refractive index difference between the antiglare layer and the support and the resulting color unevenness are improved.

  It does not specifically limit as a binder which forms a glare-proof layer. From the viewpoint of film formation, a polymer compound or a low molecular compound is preferably crosslinked to have a high molecular weight. In addition, since scratch resistance is required for use on the surface of an image display device, it is preferable to impart hard coat properties to the antiglare layer.

  In order to impart a hard coat property to the layer B, a polymer having a saturated hydrocarbon or a polyether as a main chain is preferable, and a polymer having a saturated hydrocarbon as a main chain is more preferable. The binder polymer is preferably crosslinked. The polymer having a saturated hydrocarbon as the main chain is preferably obtained by a polymerization reaction of an ethylenically unsaturated monomer. In order to obtain a crosslinked binder polymer, it is preferable to use a monomer having two or more ethylenically unsaturated groups.

  Examples of monomers having two or more ethylenically unsaturated groups include esters of polyhydric alcohols and (meth) acrylic acid (eg, ethylene glycol di (meth) acrylate, 1,4-dichlorohexane diacrylate, penta Erythritol tetra (meth) acrylate), pentaerythritol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolethane tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) Acrylate, pentaerythritol hexa (meth) acrylate, 1,2,3-cyclohexanetetramethacrylate, polyurethane polyacrylate, polyester polyacrylate), vinylbenzene and its derivatives (examples) 1,4-divinylbenzene, 4-vinylbenzoic acid-2-acryloylethyl ester, 1,4-divinylcyclohexanone), vinyl sulfone (eg, divinyl sulfone), acrylamide (eg, methylenebisacrylamide) and methacrylamide are included. . The polymer having a polyether as the main chain is preferably synthesized by a ring-opening polymerization reaction of a polyfunctional epoxy compound. These monomers having an ethylenically unsaturated group need to be cured by a polymerization reaction by ionizing radiation or heat after coating.

  Instead of or in addition to the monomer having two or more ethylenically unsaturated groups, a crosslinked structure may be introduced into the binder polymer by the reaction of a crosslinkable group. Examples of the crosslinkable functional group include an isocyanate group, an epoxy group, an aziridine group, an oxazoline group, an aldehyde group, a carbonyl group, a hydrazine group, a carboxyl group, a methylol group, and an active methylene group. Vinylsulfonic acid, acid anhydride, cyanoacrylate derivative, melamine, etherified methylol, ester and urethane, and metal alkoxide such as tetramethoxysilane can also be used as a monomer for introducing a crosslinked structure. A functional group that exhibits crosslinkability as a result of the decomposition reaction, such as a block isocyanate group, may be used. In the present invention, the cross-linking group is not limited to the above compound, and may be one showing reactivity as a result of decomposition of the functional group. These compounds having a crosslinking group need to be crosslinked by heat after application.

  In order to increase the refractive index of the binder of the layer B, it is preferable to use a high refractive index monomer having a refractive index of 1.57 to 2.00. More preferably, a high refractive index monomer of 1.65 or more is used. Examples of the high refractive index monomer include bis (4-methacryloylthiophenyl) sulfide, vinyl naphthalene, vinyl phenyl sulfide, 4-methacryloxyphenyl-4′-methoxyphenyl thioether, and the like. The polymer having a polyether as the main chain is preferably synthesized by a ring-opening polymerization reaction of a polyfunctional epoxy compound. These monomers having an ethylenically unsaturated group need to be cured by a polymerization reaction by ionizing radiation or heat after coating.

Further, in order to increase the refractive index of the binder of the layer B, the particle size is 100 nm or less, preferably 50 nm or less, made of an oxide of at least one metal selected from titanium, aluminum, indium, zinc, tin, and antimony. It is preferable to contain fine particles. Examples of the fine _{particles, TiO 2, Al 2 O 3} , In 2 O 3, ZnO, SnO 2, Sb 2 O 3, ZrO 2, ITO and the like. The amount of the inorganic fine particles added is preferably 10 to 90% by weight, more preferably 20 to 80% by weight, and particularly preferably 30 to 60% by weight based on the total weight of the layer B.

Next, the layer C will be described. The antiglare antireflection film of the present invention has at least one low refractive index layer having a refractive index of 1.38 to 1.49 containing a fluorine-containing compound as an uppermost layer. This low refractive index layer may be applied directly on the antiglare layer, or may be applied on the antiglare layer via another layer. The low refractive index layer preferably satisfies the following formula (I).
(Mλ / 4) × 0.7 <n ₁ d ₁ <(mλ / 4) × 1.3 Formula (I)
In the formula, m is a positive odd number (generally 1), n ₁ is the refractive index of the low refractive index layer, and d ₁ is the film thickness (nm) of the low refractive index layer. Further, λ is a wavelength and is a value in the range of 500 to 550 nm. In addition, satisfy | filling said numerical formula (I) means that m (positive odd number, usually 1) which satisfy | fills numerical formula (I) exists in the said wavelength range.

  The fluorine-containing compound used for the low refractive index layer is not particularly limited as long as it is a fluorine-containing compound having a refractive index of 1.38 to 1.49. From the viewpoint of antifouling properties and scratch resistance, a crosslinkable fluorine-containing compound that is crosslinked by heat or ionizing radiation having a dynamic friction coefficient of 0.03 to 0.15 and a contact angle with water of 90 to 120 ° is more preferable. In order to adjust coatability, film hardness, etc., other compounds may be used in combination.

  As the crosslinkable fluorine-containing compound before crosslinking used for the low refractive index layer, in addition to a perfluoroalkyl group-containing silane compound (for example, (heptadecafluoro-1,1,2,2-tetradecyl) triethoxysilane), etc., Examples thereof include a fluorine-containing copolymer having a fluorine-containing monomer and a monomer for imparting a crosslinkable group as structural units. Specific examples of the fluorine-containing monomer unit include, for example, fluoroolefins (for example, fluoroethylene, vinylidene fluoride, tetrafluoroethylene, hexafluoroethylene, hexafluoropropylene, perfluoro-2,2-dimethyl-1,3-dioxole, etc. ), (Meth) acrylic acid moieties or fully fluorinated alkyl ester derivatives (for example, Biscoat 6FM (manufactured by Osaka Organic Chemicals) and M-2020 (manufactured by Daikin)), fully or partially fluorinated vinyl ethers, and the like. As a monomer for imparting a crosslinkable group, in addition to a (meth) acrylate monomer having a crosslinkable functional group in the molecule in advance such as glycidyl methacrylate, it has a carboxyl group, a hydroxyl group, an amino group, a sulfonic acid group, etc. ) Acrylate monomers (for example, (meth) acrylic acid, methylol (meth) acrylate, hydroxyalkyl (meth) acrylate, allyl acrylate, etc.). It is described in JP-A-10-25388 and JP-A-10-147739 that the latter can introduce a crosslinked structure after copolymerization.

  Moreover, not only the copolymer of the said fluorine-containing monomer but a copolymer with the monomer which does not contain a fluorine atom may be used. The monomer that can be used in combination is not particularly limited. For example, olefins (ethylene, propylene, isoprene, vinyl chloride, vinylidene chloride, etc.), acrylic esters (methyl acrylate, methyl acrylate, ethyl acrylate, 2-acrylic acid 2- Ethyl hexyl), methacrylates (methyl methacrylate, ethyl methacrylate, butyl methacrylate, ethylene glycol dimethacrylate, etc.), styrene derivatives (styrene, divinylbenzene, vinyl toluene, α-methylstyrene, etc.), vinyl ethers (methyl vinyl ether) Etc.), vinyl esters (vinyl acetate, vinyl propionate, vinyl cinnamate, etc.), acrylamides (N-tertbutylacrylamide, N-cyclohexylacrylamide, etc.), methacrylamides, Other B such nitrile derivatives, as commercially available products can JN-7219, JN-7221, JN-7225 (both JSR (Ltd.)) exemplified. JN-7219, JN-7221 and JN-7225 also have slipperiness, and from the viewpoint of achieving both low refractive index, slipperiness and antifouling properties, the low refractive index layer has JN-7219, JN-7221, JN-7225 is preferred.

The transparent support A of the film of the present invention is not particularly limited, such as a transparent resin film, a transparent resin plate, a transparent resin sheet, and transparent glass. Transparent resin films include cellulose acylate films (for example, cellulose triacetate film (refractive index 1.48), cellulose diacetate film, cellulose acetate butyrate film, cellulose acetate propionate film), polyethylene terephthalate film, polyethersulfone. Films, polyacrylic resin films, polyurethane resin films, polyester films, polycarbonate films, polysulfone films, polyether films, polymethylpentene films, polyetherketone films, (meth) acrylonitrile films, and the like can be used.
Although the thickness of a support body can use the thing of about 25 micrometers-1000 micrometers normally, Preferably it is 25 micrometers-250 micrometers, and it is more preferable that it is 30 micrometers-90 micrometers.
Any width of the support can be used, but from the viewpoint of handling, yield, and productivity, a width of 100 to 5000 mm is usually used, preferably 800 to 3000 mm, and preferably 1000 to 2000 mm. More preferably.
The surface of the support is preferably smooth, and the average roughness Ra is preferably 1 μm or less, preferably 0.0001 to 0.5 μm, and 0.001 to 0.1 μm. Is more preferable.

<Cellulose acylate film>
Among the various films described above, a cellulose acylate film having high transparency, optically low birefringence, easy production, and generally used as a protective film for polarizing plates is preferable.
For cellulose acylate films, various improvement techniques are known for the purpose of improving mechanical properties, transparency, flatness and the like, and the techniques described in the published technical reports 2001-1745 are known as the present invention. It can be used for the film.

In the present invention, among the cellulose acylate films, a cellulose triacetate film is particularly preferable, and it is preferable to use cellulose acetate having an acetylation degree of 59.0 to 61.5% for the cellulose acylate film. The degree of acetylation means the amount of bound acetic acid per unit mass of cellulose. The degree of acetylation follows the measurement and calculation of the degree of acetylation in ASTM: D-817-91 (test method for cellulose acetate and the like).
The viscosity average degree of polymerization (DP) of cellulose acylate is preferably 250 or more, and more preferably 290 or more.
In addition, the cellulose acylate used in the present invention has a Mw / Mn (Mw is mass average molecular weight, Mn is number average molecular weight) value by gel permeation chromatography close to 1.0, in other words, a molecular weight distribution. Narrow is preferred. The specific value of Mw / Mn is preferably 1.0 to 1.7, more preferably 1.3 to 1.65, and most preferably 1.4 to 1.6. preferable.

In general, the 2, 3, and 6 hydroxyl groups of cellulose acylate are not evenly distributed by 1/3 of the total substitution degree, and the substitution degree of the 6-position hydroxyl group tends to be small. In the present invention, it is preferable that the substitution degree of the 6-position hydroxyl group of cellulose acylate is larger than that of the 2- and 3-positions.
The hydroxyl group at the 6-position with respect to the total degree of substitution is preferably substituted with an acyl group of 32% or more, more preferably 33% or more, and particularly preferably 34% or more. Furthermore, the substitution degree of the 6-position acyl group of cellulose acylate is preferably 0.88 or more. The 6-position hydroxyl group may be substituted with a propionyl group, butyroyl group, valeroyl group, benzoyl group, acryloyl group or the like, which is an acyl group having 3 or more carbon atoms, in addition to the acetyl group. The degree of substitution at each position can be determined by NMR.
In the present invention, as cellulose acylate, paragraphs “0043” to “0044” [Example] [Synthesis Example 1], paragraphs “0048” to “0049” [Synthesis Example 2], paragraph “ Cellulose acetate obtained by the method described in “0051” to “0052” [Synthesis Example 3] can be used.

<Manufacture of cellulose acylate film>
The cellulose acylate film used in the present invention can be produced by a solution casting method (solvent casting method). In the solvent cast method, a film is produced using a solution (dope) in which cellulose acylate is dissolved in an organic solvent.

  The organic solvent is a solvent selected from ethers having 3 to 12 carbon atoms, ketones having 3 to 12 carbon atoms, esters having 3 to 12 carbon atoms, and halogenated hydrocarbons having 1 to 6 carbon atoms. It is preferable to contain. Two or more organic solvents may be mixed and used.

  The ether, ketone and ester may have a cyclic structure. A compound having two or more functional groups of ether, ketone and ester (that is, —O—, —CO— and —COO—) can also be used as the organic solvent. The organic solvent may have another functional group such as an alcoholic hydroxyl group. In the case of an organic solvent having two or more types of functional groups, the preferred number of carbon atoms may be within the range of the preferred number of carbon atoms specified above for the compound having any functional group.

Examples of the ether having 3 to 12 carbon atoms include diisopropyl ether, dimethoxymethane, dimethoxyethane, 1,4-dioxane, 1,3-dioxolane, tetrahydrofuran, anisole and phenetole.
Examples of ketones having 3 to 12 carbon atoms include acetone, methyl ethyl ketone, diethyl ketone, diisobutyl ketone, cyclohexanone and methylcyclohexanone.
Examples of the esters having 3 to 12 carbon atoms include ethyl formate, propyl formate, pentyl formate, methyl acetate, ethyl acetate and pentyl acetate.

  Examples of the organic solvent having two or more kinds of functional groups include 2-ethoxyethyl acetate, 2-methoxyethanol and 2-butoxyethanol.

  The number of carbon atoms of the halogenated hydrocarbon is preferably 1 or 2, and most preferably 1. The halogen of the halogenated hydrocarbon is preferably chlorine. The proportion of halogen atoms substituted by halogen in the halogenated hydrocarbon is preferably 25 to 75 mol%, more preferably 30 to 70 mol%, and more preferably 35 to 65 mol%. More preferably, it is most preferable that it is 40-60 mol%. Methylene chloride is a representative halogenated hydrocarbon.

The cellulose acylate solution (dope) can be prepared by a general method. A general method means processing at a temperature of 0 ° C. or higher (room temperature or high temperature). The solution can be prepared by using a dope preparation method and apparatus in a normal solvent cast method. In the case of a general method, it is preferable to use a halogenated hydrocarbon (particularly methylene chloride) as the organic solvent. A non-chlorinated solvent can also be used, and examples thereof include those described in JIII Journal of Technical Disclosure No. 2001-1745.
The amount of cellulose acylate is adjusted so as to be contained in the obtained solution in an amount of 10 to 40% by mass. The amount of cellulose acylate is more preferably 10 to 30% by mass. Arbitrary additives described later may be added to the organic solvent (main solvent).
The solution can be prepared by stirring cellulose acylate and an organic solvent at room temperature (0 to 40 ° C.). High concentration solutions may be stirred under pressure and heating conditions. Specifically, cellulose acylate and an organic solvent are placed in a pressure vessel and sealed, and stirred while being heated to a temperature equal to or higher than the boiling point of the solvent at normal temperature and in a range where the solvent does not boil. The heating temperature is usually 40 ° C. or higher, preferably 60 to 200 ° C., more preferably 80 to 110 ° C.

Each component may be coarsely mixed in advance and then placed in a container. Moreover, you may put into a container sequentially.
The container needs to be configured so that it can be stirred. The container can be pressurized by injecting an inert gas such as nitrogen gas. Moreover, you may utilize the raise of the vapor pressure of the solvent by heating. Or after sealing a container, you may add each component under pressure.
When heating, it is preferable to heat from the outside of the container. For example, a jacket type heating device can be used. The entire container can also be heated by providing a plate heater outside the container and piping to circulate the liquid.
It is preferable to provide a stirring blade inside the container and stir using this. The stirring blade preferably has a length that reaches the vicinity of the wall of the container. A scraping blade is preferably provided at the end of the stirring blade in order to renew the liquid film on the vessel wall.
Instruments such as a pressure gauge and a thermometer may be installed in the container. Each component is dissolved in a solvent in the container. The prepared dope is taken out of the container after cooling, or taken out and then cooled using a heat exchanger or the like.

A solution can also be prepared by a cooling dissolution method. In the cooling dissolution method, cellulose acylate can be dissolved in an organic solvent that is difficult to dissolve by a normal dissolution method. In addition, even if it is a solvent which can melt | dissolve a cellulose acetate with a normal melt | dissolution method, there exists an effect that a uniform solution can be obtained rapidly according to a cooling melt | dissolution method.
In the cooling dissolution method, first, cellulose acylate is gradually added to an organic solvent at room temperature while stirring.
The amount of cellulose acylate is preferably adjusted so as to be contained in the mixture at 10 to 40% by mass. The amount of cellulose acylate is more preferably 10 to 30% by mass. Furthermore, you may add the arbitrary additive mentioned later in a mixture.

The mixture is then cooled to -100 to -10 ° C (preferably -80 to -10 ° C, more preferably -50 to -20 ° C, most preferably -50 to -30 ° C). The cooling can be performed, for example, in a dry ice / methanol bath (−75 ° C.) or a cooled diethylene glycol solution (−30 to −20 ° C.). When cooled in this way, the mixture of cellulose acetate and organic solvent solidifies.
The cooling rate is preferably 4 ° C./min or more, more preferably 8 ° C./min or more, and most preferably 12 ° C./min or more. The faster the cooling rate, the better. However, 10,000 ° C./second is the theoretical upper limit, 1000 ° C./second is the technical upper limit, and 100 ° C./second is the practical upper limit. The cooling rate is a value obtained by dividing the difference between the temperature at the start of cooling and the final cooling temperature by the time from the start of cooling to the final cooling temperature.

Further, when this is heated to 0 to 200 ° C. (preferably 0 to 150 ° C., more preferably 0 to 120 ° C., most preferably 0 to 50 ° C.), cellulose acetate is dissolved in the organic solvent. The temperature can be raised by simply leaving it at room temperature or in a warm bath.
The heating rate is preferably 4 ° C./min or more, more preferably 8 ° C./min or more, and most preferably 12 ° C./min or more. The higher the heating rate, the better. However, 10,000 ° C./second is the theoretical upper limit, 1000 ° C./second is the technical upper limit, and 100 ° C./second is the practical upper limit. The heating rate is a value obtained by dividing the difference between the temperature at the start of heating and the final heating temperature by the time from the start of heating until the final heating temperature is reached. .
A uniform solution is obtained as described above. If the dissolution is insufficient, the cooling and heating operations may be repeated. Whether or not the dissolution is sufficient can be determined by merely observing the appearance of the solution with the naked eye.

In the cooling dissolution method, it is desirable to use a sealed container in order to avoid moisture mixing due to condensation during cooling. In the cooling and heating operation, when the pressure is applied during cooling and the pressure is reduced during heating, the dissolution time can be shortened. In order to perform pressurization and decompression, it is desirable to use a pressure-resistant container.
In addition, according to differential scanning calorimetry (DSC), a 20 mass% solution obtained by dissolving cellulose acetate (acetylation degree: 60.9%, viscosity average polymerization degree: 299) in methyl acetate by a cooling dissolution method was 33. There exists a quasi-phase transition point between a sol state and a gel state in the vicinity of ° C., and a uniform gel state is obtained below this temperature. Therefore, this solution needs to be maintained at a temperature equal to or higher than the pseudo phase transition temperature, preferably about the gel phase transition temperature plus about 10 ° C. However, this pseudo phase transition temperature varies depending on the degree of acetylation of cellulose acetate, the degree of viscosity average polymerization, the concentration of the solution, and the organic solvent used.

A cellulose acylate film is produced from the prepared cellulose acylate solution (dope) by a solvent cast method.
The dope is cast on a drum or band and the solvent is evaporated to form a film. The concentration of the dope before casting is preferably adjusted so that the solid content is 18 to 35%.
The surface of the drum or band is preferably finished in a mirror state. The casting and drying methods in the solvent casting method are described in U.S. Pat. No. 7,736892, JP-B Nos. 45-4554, 49-5614, and 62-1115035.
The dope is preferably cast on a drum or band having a surface temperature of 10 ° C. or less.
After casting, it is preferable to dry it by applying air for 2 seconds or more. The obtained film can be peeled off from the drum or band, and further dried by high-temperature air whose temperature is successively changed from 100 to 160 ° C. to evaporate the residual solvent. The above method is described in Japanese Patent Publication No. 5-17844. According to this method, it is possible to shorten the time from casting to stripping. In order to carry out this method, it is necessary for the dope to gel at the surface temperature of the drum or band during casting.

A film can also be produced by casting two or more layers by a solvent casting method using a plurality of prepared cellulose acylate solutions (dope). In this case, the dope is cast on a drum or band and the solvent is evaporated to form a film. It is preferable to adjust the concentration of the dope before casting so that the solid content is 10 to 40% by mass. The surface of the drum or band is preferably finished in a mirror state.

  When casting a plurality of cellulose acylate liquids of two or more layers, it is possible to cast a plurality of cellulose acylate solutions, and cellulose is supplied from a plurality of casting openings provided at intervals in the traveling direction of the support. A film may be produced while casting and laminating a solution containing an acylate. For example, in each publication such as JP-A Nos. 61-158414, 1-122419, 11-198285, etc. The described method is applicable. Further, it may be formed into a film by casting a cellulose acylate solution from two casting ports. For example, JP-B-60-27562, JP-A-61-94724, JP-A-61-104813, It can be carried out by the methods described in JP-A Nos. 61-158413 and 6-134933. Further, a cellulose acylate film in which a flow of a high-viscosity cellulose acylate solution described in JP-A-56-162617 is wrapped with a low-viscosity cellulose acylate solution and the high-low viscosity cellulose acylate solution is simultaneously extruded. A casting method may be used.

  Alternatively, by using two casting ports, the film cast on the support is peeled off by the first casting port, and the second casting is performed on the side that is in contact with the support surface. For example, it is a method described in Japanese Patent Publication No. 44-20235. The cellulose acylate solutions to be cast may be the same solution or different cellulose acylate solutions, and are not particularly limited. In order to give a function to a plurality of cellulose acylate layers, a cellulose acylate solution corresponding to the function may be extruded from each casting port.

  Furthermore, in the present invention, the cellulose acylate solution is cast simultaneously with a solution for forming other functional layers (for example, an adhesive layer, a dye layer, an antistatic layer, an antihalation layer, a UV absorbing layer, a polarizing layer, etc.) Simultaneous formation of the layer and film formation can also be carried out.

  In the case of a single-layer solution, it is necessary to extrude a high-concentration and high-viscosity cellulose acylate solution to obtain the required film thickness. In this case, the stability of the cellulose acylate solution is poor and solids are generated. In many cases, however, it becomes a problem due to a failure or a poor flatness. As this solution, a plurality of cellulose acylate solutions are cast from a casting port. As a result, it is possible to extrude a highly viscous solution onto the support at the same time, not only can the flatness be improved and an excellent planar film can be produced, but also a concentrated cellulose acylate solution can be used to reduce the drying load. Reduction can be achieved and film production speed can be increased.

A plasticizer can be added to the cellulose acylate film in order to improve the mechanical properties or to improve the drying rate after casting during film production. As the plasticizer, phosphoric acid ester or carboxylic acid ester is used. Examples of phosphate esters include triphenyl phosphate (TPP), diphenyl biphenyl phosphate, and tricresyl phosphate (TCP). Representative examples of the carboxylic acid ester include phthalic acid esters and citric acid esters. Examples of phthalic acid esters include dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), dioctyl phthalate (DOP), diphenyl phthalate (DPP) and diethyl hexyl phthalate (DEHP). Examples of citrate esters include triethyl O-acetylcitrate (OACTE) and tributyl O-acetylcitrate (OACTB). Examples of other carboxylic acid esters include butyl oleate, methylacetyl ricinoleate, dibutyl sebacate, and various trimellitic acid esters. Phthalate plasticizers (DMP, DEP, DBP, DOP, DPP, DEHP) are preferably used. DEP and DPP are particularly preferred.
The addition amount of the plasticizer is preferably 0.1 to 25% by mass of the amount of cellulose acylate, more preferably 1 to 20% by mass, and most preferably 3 to 15% by mass.

  A degradation inhibitor (eg, antioxidant, peroxide decomposer, radical inhibitor, metal deactivator, acid scavenger, amine) may be added to the cellulose acylate film. The deterioration inhibitors are described in JP-A-3-199201, JP-A-597073, JP-A-5-194789, JP-A-5-271471, and JP-A-6-107854. The addition amount of the deterioration preventing agent is preferably 0.01 to 1% by mass of the solution (dope) to be prepared in consideration of the effect of the deterioration preventing agent and bleeding out (bleeding out) to the film surface. More preferably, the content is 0.01 to 0.2% by mass. Examples of particularly preferred deterioration inhibitors include butylated hydroxytoluene (BHT) and tribenzylamine (TBA).

In the cellulose acylate film, a retardation increasing agent can be used as necessary in order to adjust the retardation of the film. The retardation of the film is preferably 0 to 300 nm in the film thickness direction and 0 to 1000 nm in the in-plane direction.
An aromatic compound having at least two aromatic rings is preferable as the retardation increasing agent, and the aromatic compound is used in an amount of 0.01 to 20 parts by mass with respect to 100 parts by mass of cellulose acylate. The aromatic compound is preferably used in the range of 0.05 to 15 parts by mass, and more preferably in the range of 0.1 to 10 parts by mass with respect to 100 parts by mass of cellulose acetate. Two or more aromatic compounds may be used in combination.
Details are described in Japanese Patent Application Laid-Open Nos. 2000-1111914, 2000-275434, 2002-236215, and International Publication No. 00/065384.

<Stretching treatment of cellulose acylate film>
The produced cellulose acylate film can further improve drying unevenness, film thickness unevenness caused by drying shrinkage, and surface unevenness by stretching treatment. The stretching treatment is also used for adjusting the retardation.
Although there is no limitation in particular in the method of the width direction extending | stretching process, the extending | stretching method by a tenter is mentioned as the example.
More preferably, the longitudinal stretching is performed in the longitudinal direction of the roll, and the longitudinal stretching is performed by adjusting the draw ratio of each pass roll (rotational ratio between the pass rolls) between the pass rolls that transport the roll film. Is possible.

<Polyethylene terephthalate film>
In the present invention, the polyethylene terephthalate film is also preferably used because it is excellent in transparency, mechanical strength, flatness, chemical resistance and moisture resistance, and is inexpensive.
In order to further improve the adhesion strength between the transparent plastic film and the hard coat layer provided thereon, the transparent plastic film is more preferably subjected to an easy adhesion treatment.
Examples of commercially available PET films with an easily adhesive layer for optics include Toyobo Co., Ltd. Cosmo Shine A4100 and A4300.

  From the viewpoint of use as a surface protective film of an image display device, as the transparent support A, cellulose acylate such as triacetyl cellulose is used for LCD, and polyethylene terephthalate or polyethylene naphthalate is used for PDP and CRT. Other than these supports, polycarbonate is preferable for other rear projections.

  Each layer of the antireflection film is formed by coating by a dip coating method, an air knife coating method, a curtain coating method, a roller coating method, a wire bar coating method, a gravure coating method or an extrusion coating method (US Pat. No. 2,681,294). can do. Two or more layers may be applied simultaneously. The method of simultaneous application is described in US Pat. Nos. 2,761,791, 2,941,898, 3,508,947, and 3,526,528 and Yuji Harasaki, Coating Engineering, page 253, Asakura Shoten (1973).

  The antireflection film is applied to an image display device such as a liquid crystal display device (LCD), a plasma display panel (PDP), an electroluminescence display (ELD), or a cathode ray tube display device (CRT). When the antireflection film has a transparent support, the transparent support side is bonded to the image display surface of the image display device.

In the present invention, the transparent support to be used may be saponified in advance. Further, a saponification treatment may be performed after applying a hard coat layer on the support, and then an antiglare layer and a low refractive index layer may be applied.
Moreover, when creating a polarizing plate using the film of the present invention as one of the surface protective films of two polarizing films, the surface on the side to be bonded to the polarizing film is made hydrophilic so that It is preferred to improve adhesion.

a. Method of immersing in alkaline solution This is a method of saponifying all surfaces that are reactive with alkali on the entire surface of the film by immersing the film in an alkaline solution under appropriate conditions, and no special equipment is required. From the viewpoint of cost. The alkaline liquid is preferably a sodium hydroxide aqueous solution. A preferred concentration is 0.5 to 3 mol / L, particularly preferably 1 to 2 mol / L. The liquid temperature of a preferable alkali liquid is 30-75 degreeC, Most preferably, it is 40-60 degreeC.
The combination of the saponification conditions is preferably a combination of relatively mild conditions, but can be set according to the material and composition of the film and the target contact angle.
After being immersed in the alkaline solution, it is preferable to sufficiently wash with water or neutralize the alkaline component by immersing in a dilute acid so that the alkaline component does not remain in the film.

By saponification treatment, the surface opposite to the surface having the coating layer is hydrophilized. The protective film for polarizing plate is used by adhering the hydrophilic surface of the transparent support to the polarizing film.
The hydrophilized surface is effective for improving the adhesiveness with the adhesive layer mainly composed of polyvinyl alcohol.
In the saponification treatment, the lower the contact angle with respect to the surface of the transparent support opposite to the side having the coating layer, the better from the viewpoint of adhesion to the polarizing film, while the dipping method simultaneously has the coating layer. Since it is damaged by alkali from the surface to the inside, it is important to set the minimum reaction conditions. When the contact angle to water of the transparent support on the opposite surface is used as an index of damage to each layer due to alkali, particularly when the transparent support is triacetylcellulose, preferably 10 to 50 degrees, more preferably Is 30 to 50 degrees, more preferably 40 to 50 degrees. If it is 50 degrees or more, there is a problem in the adhesion to the polarizing film, which is not preferable. On the other hand, if it is less than 10 degrees, the film suffers too much damage, which impairs physical strength and is not preferable.

b. Method of applying alkaline solution As a means of avoiding damage to each film in the above-mentioned immersion method, an alkali solution is applied, heated, washed with water, and dried only on the surface opposite to the surface having the coating layer under appropriate conditions. A liquid coating method is preferably used. The application in this case means that an alkaline solution or the like is brought into contact only with the surface to be saponified, and in addition to the application, it may be carried out by spraying or contacting a belt containing the solution. Including. By adopting these methods, a separate facility and process for applying an alkaline solution are required, which is inferior to the immersion method (1) from the viewpoint of cost. On the other hand, since the alkali solution contacts only the surface to be saponified, the opposite surface can have a layer using a material that is weak against the alkali solution. For example, vapor deposition films and sol-gel films have various effects such as corrosion, dissolution, and peeling due to alkali solution, so it is not desirable to use the immersion method. Is possible.

  In any of the saponification methods (1) and (2), since each layer can be formed by unwinding from a roll-shaped support, it may be performed by a series of operations in addition to the film manufacturing process. . Furthermore, the polarizing plate can be produced more efficiently than the same operation with a single wafer by continuously performing the pasting step with the polarizing plate made of the unwound support.

c. Method of protecting and saponifying with a laminate film As in (2) above, when the coating layer is insufficient in resistance to an alkaline solution, a laminate film is pasted on the surface on which the final layer is formed after forming the final layer. By immersing them in an alkaline solution after combining them, only the triacetyl cellulose surface opposite to the surface on which the final layer is formed can be hydrophilized, and then the laminate film can be peeled off. Even in this method, the hydrophilic treatment necessary for the polarizing plate protective film can be applied only to the surface opposite to the surface on which the final layer of the triacetyl cellulose film is formed without damaging the coating layer. Compared with the method (2), there is an advantage that a laminate film is generated as waste, but a device for applying a special alkaline solution is unnecessary.

d. Method of immersing in alkaline solution after forming up to middle layer Although resistant to alkaline solution up to lower layer, but insufficient resistance to alkaline solution of upper layer, dip into alkaline solution after forming up to lower layer to make both sides hydrophilic The upper layer can also be formed after processing. Although the manufacturing process is complicated, for example, in a film composed of an antiglare layer and a low refractive index layer of a fluorine-containing sol-gel film, when there is a hydrophilic group, the interlayer adhesion between the antiglare layer and the low refractive index layer is improved. There are advantages to doing.

e. Method of forming a coating layer on a saponified triacetyl cellulose film A saponification of a triacetyl cellulose film by immersing it in an alkaline solution in advance and applying the coating layer directly on one side or via another layer It may be formed. In the case of saponification by dipping in an alkaline solution, the interlayer adhesion with the triacetyl cellulose surface hydrophilized by saponification may deteriorate. In such a case, after saponification, only the surface on which the coating layer is to be formed is treated by corona discharge, glow discharge or the like to remove the hydrophilic surface and then form the coating layer. Further, when the coating layer has a hydrophilic group, the interlayer adhesion may be good.

  In order to describe the present invention in detail, examples will be described below, but the present invention is not limited thereto. Unless otherwise specified, “part” and “%” are based on mass.

(Synthesis of perfluoroolefin copolymer (1))

A 40 ml stainless steel autoclave with a stirrer was charged with 40 ml of ethyl acetate, 14.7 g of hydroxyethyl vinyl ether and 0.55 g of dilauroyl peroxide, and the system was degassed and replaced with nitrogen gas. Furthermore, 25 g of hexafluoropropylene (HFP) was introduced into the autoclave and the temperature was raised to 65 ° C. The pressure when the temperature in the autoclave reached 65 ° C. was 0.53 Mpa (5.4 kg / cm ² ). The reaction was continued for 8 hours while maintaining the temperature, and when the pressure reached 0.31 MPa (3.2 kg / cm ² ), the heating was stopped and the mixture was allowed to cool. When the internal temperature dropped to room temperature, unreacted monomers were driven out, the autoclave was opened, and the reaction solution was taken out. The obtained reaction solution was poured into a large excess of hexane, and the polymer was precipitated by removing the solvent by decantation. Further, this polymer was dissolved in a small amount of ethyl acetate and reprecipitated twice from hexane to completely remove the residual monomer. After drying, 28 g of polymer was obtained. Next, 20 g of the polymer was dissolved in 100 ml of N, N-dimethylacetamide, and 11.4 g of acrylic acid chloride was added dropwise under ice cooling, followed by stirring at room temperature for 10 hours. Ethyl acetate was added to the reaction solution, washed with water, the organic layer was extracted and concentrated, and the resulting polymer was reprecipitated with hexane to obtain 19 g of perfluoroolefin copolymer (1). The resulting polymer had a refractive index of 1.421.

(Preparation of sol solution)
A stirrer, a reactor equipped with a reflux condenser, 120 parts of methyl ethyl ketone, 100 parts of acryloyloxypropyltrimethoxysilane (KBM-5103, manufactured by Shin-Etsu Chemical Co., Ltd.), 3 parts of diisopropoxyaluminum ethyl acetoacetate were added and mixed. Thereafter, 30 parts of ion-exchanged water was added and reacted at 60 ° C. for 4 hours, and then cooled to room temperature to obtain sol solution a. The mass average molecular weight was 1600, and among the components higher than the oligomer component, the component having a molecular weight of 1000 to 20000 was 100%. Further, from the gas chromatography analysis, the raw material acryloyloxypropyltrimethoxysilane did not remain at all.

(Preparation of dispersion A)
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-A-2002-79616. Prepared) 30 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 silica content was almost constant, solvent substitution was performed by distillation under reduced pressure at a pressure of 20 kPa. 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 A was analyzed by gas chromatography, it was 1.5%.

[Example 1]
(Preparation of coating solution A for internal scattering layer)
71.0 g of a mixture of pentaerythritol triacrylate and pentaerythritol tetraacrylate (PET-30, Nippon Kayaku Co., Ltd.) and 3.0 g of a polymerization initiator (Irgacure 184, Ciba Specialty Chemicals Co., Ltd.) , 0.1 g of fluorine-based surface modifier (FP-149) and 11.9 g of silane coupling agent (KBM-5103, manufactured by Shin-Etsu Chemical Co., Ltd.) are added to a mixed solvent of methyl isobutyl ketone and methyl ethyl ketone, and air The solute was completely dissolved by stirring for 60 minutes with a disper. The refractive index of the coating film obtained by applying this solution and curing with ultraviolet rays was 1.520. 6.3 g of crosslinked poly (styrene) particles having an average particle size of 3.5 μm (refractive index of 1.600) and crosslinked poly (acryl-styrene) particles having an average particle size of 3.5 μm (copolymerization composition ratio = 50/50, refraction) (Rate 1.536) 7.7 g was dispersed with a Polytron disperser at 10,000 rpm for 20 minutes, added as a 30% methyl isobutyl ketone dispersion, methyl isobutyl ketone and methyl ethyl ketone were added, and the ratio of methyl isobutyl ketone to methyl ethyl ketone was 70 pairs. 30. After adjusting the solid content concentration to 45% by mass, the mixture was stirred with an air disper for 10 minutes.
The mixed solution was filtered through a polypropylene filter having a pore size of 30 μm to prepare a coating solution A for internal scattering layer.

(Adjustment of coating solution A for low refractive index layer)
With respect to 783.3 parts by mass (47.0 parts by mass as a solid content) of OPSTA JTA113 (thermally crosslinkable fluorine-containing silicone polymer composition liquid (solid content: 6%): manufactured by JSR Corporation), dispersion A was 195 Mass parts (silica + 39.0 parts by mass as surface treatment agent solid content), colloidal silica dispersion (silica, MEK-ST particle size difference, average particle size 45 nm, solid content concentration 30%, Nissan Chemical Co., Ltd. 30.0 parts by mass (9.0 parts by mass as solid content) and 17.2 parts by mass of sol liquid a (5.0 parts by mass as solids) were added. The coating liquid A for low refractive index was prepared by diluting with cyclohexane and methyl ethyl ketone so that the solid content concentration of the entire coating liquid was 6% by mass and the ratio of cyclohexane and methyl ethyl ketone was 10:90. The refractive index of the layer formed by this coating solution was 1.39.

(1) Coating of internal scattering layer A 80 μm thick triacetyl cellulose film (TAC-TD80U, manufactured by Fuji Photo Film Co., Ltd.) is unrolled in the form of a roll, and the die coat shown by the following apparatus configuration and coating conditions The coating solution A for the internal scattering layer was applied by the method, dried at 30 ° C. for 15 seconds and 90 ° C. for 20 seconds, and then air-cooled metal halide lamp (manufactured by Eye Graphics Co., Ltd.) of 160 W / cm under a nitrogen purge. Then, the coating layer was cured by irradiating ultraviolet rays with an irradiation amount of 90 mJ / cm ² to form an internal scattering layer having a thickness of 7.2 μm and wound up. By controlling the time to start applying the drying air in 2 to 10 seconds after coating, the appearance of surface irregularities was controlled. The particle density in the formed film was 1.21 g / m ² .

Basic conditions: The slot die has an upstream lip land length I _UP of 0.5 mm, a downstream lip land length I _LO of 50 μm, a length of the slot opening in the web running direction of 150 μm, and a slot length of 50 mm. I used one. The gap between the upstream lip land and the web was 50 μm longer than the gap between the downstream lip land and the web, and the gap _GL between the downstream lip land and the web was set to 50 μm. Further, the gap G _S between the side plates and the web of the decompression chamber, and the gap G _B between the back plate and the web were both 200 [mu] m.

(2) Coating of Low Refractive Index Layer The triacetyl cellulose film coated with the internal scattering layer coating liquid A and coated with the internal scattering layer is unwound again to form the low refractive index layer coating liquid A. After being dried at 120 ° C. for 150 seconds and further dried at 140 ° C. for 8 minutes, a 240 W / cm air-cooled metal halide lamp (eye graphics) under an atmosphere with an oxygen concentration of 0.1% by nitrogen purge. Ltd.) was used to an irradiation dose of 300 mJ / cm ^2, to form a low refractive index layer having a thickness of 100 nm, it was wound.
(3) Saponification treatment of antireflection film After forming the low refractive index layer, the sample was subjected to the following saponification treatment.
A sodium hydroxide aqueous solution was used for the alkali treatment step, and the concentration, temperature and treatment time are shown in Table 1. Then, it was immersed in water and the sodium hydroxide aqueous solution was thoroughly washed away. Next, after immersing in a 0.01 N, 35 ° C. dilute sulfuric acid aqueous solution for 1 minute, it was immersed in water to sufficiently wash away the dilute sulfuric acid aqueous solution. Finally, the sample was thoroughly dried at 120 ° C.
In this way, a saponified antireflection film was produced. This is Example 1-1.

  The reflection of Example 1-2 was performed in the same manner as in Example 1-1 except that the addition amount of the two types of particles of the coating liquid A for internal scattering layer was changed so that the particle ratio and particle density shown in Table 1 were obtained. A prevention film was prepared.

  Example 1-3 was produced by the same production method as Example 1-1 except that the coating amount was adjusted and changed to the film thickness shown in Table 1.

  Example 1-1, except that the addition amount of the two types of particles of the coating liquid A for internal scattering layer was changed so as to obtain the particle ratio and particle density shown in Table 1, the coating amount was adjusted, and the film thickness was changed. Example 1-4 was produced by the same production method.

(Preparation of coating solution B for internal scattering layer)
A mixture of pentaerythritol triacrylate and pentaerythritol tetraacrylate (PET-30, Nippon Kayaku Co., Ltd.) 70.9 g, polymerization initiator (Irgacure 184, Ciba Specialty Chemicals Co., Ltd.) 3.4 g, fluorine System surface modifier (FP-149) 0.1g, silane coupling agent (KBM-5103, manufactured by Shin-Etsu Chemical Co., Ltd.) 13.0g is added to methyl isobutyl ketone and methyl ethyl ketone, and 60 minutes with an air disper The solute was completely dissolved by stirring. The refractive index of the coating film obtained by applying this solution and curing with ultraviolet rays was 1.523. 12.6 g of a crosslinked poly (acryl-styrene) particle having an average particle size of 3.5 μm (copolymerization composition ratio = 30/70, refractive index 1.561) was dispersed with a Polytron disperser at 10,000 rpm for 20 minutes and 30% methyl isobutyl. It added as a ketone dispersion liquid, methyl isobutyl ketone and methyl ethyl ketone were added, solid content concentration was adjusted to 43.5 mass%, and it stirred for 10 minutes with the air disper. The ratio of methyl isobutyl ketone and methyl ethyl ketone was adjusted to 80:20.
The mixed solution was filtered through a polypropylene filter having a pore size of 30 μm to prepare a coating solution B for internal scattering layer.

  A part of crosslinked poly (acryl-styrene) particles (copolymerization composition ratio = 30/70, refractive index 1.561) having a mean particle size of 3.5 μm in the coating liquid B for internal scattering layer is crosslinked poly (acryl-styrene). In place of the particles (copolymerization composition ratio = 50/50, refractive index 1.536), the addition amount of the two kinds of particles was changed so that the particle ratio and particle density shown in Table 1 were obtained, and the coating amount was adjusted. Example 1-5 was produced by the same production method as Example 1-1 except that the film thickness was changed.

  The same production method as in Example 1-5 except that the addition amount of the two types of particles in the coating liquid for internal scattering layer used in Example 1-5 was changed so that the particle ratio and particle density shown in Table 1 were obtained. Example 1-6 was produced.

  Example 1-7 was produced by changing the alkali treatment conditions of Example 1-1 to the conditions described in Table 1.

  In Example 1-1, the film thickness of the low refractive index layer was halved, and the alkali treatment conditions were processed under the same conditions as in Example 1-7 to produce Example 1-8.

  The addition amount of the two types of particles of the coating solution for internal scattering layer used in Example 1-5 was changed so that the particle ratio and particle density shown in Table 1 were obtained, the coating amount was adjusted, and the film thickness was changed. Example 1-9 was produced by the same production method as Example 1-5, except for the above.

  Example 1-10 was produced by the same production method as Example 1-1, except that the addition amount of the two types of particles of coating liquid A for internal scattering layer was changed so as to achieve the particle ratio and particle density shown in Table 1. did.

  The addition amount of the two types of particles of the coating solution for internal scattering layer used in Example 1-5 was changed so that the particle ratio and particle density shown in Table 1 were obtained, the coating amount was adjusted, and the film thickness was changed. Example 1-1 was produced in the same manner as in Example 1-5, except for Comparative Example 1-1.

  The same preparation as in Example 1-5 except that the amount of particles added to the coating liquid B for internal scattering layer was changed so as to obtain the particle ratio and particle density shown in Table 1, the coating amount was adjusted, and the film thickness was changed. Comparative Example 1-2 was produced by the method.

  Comparative Example 1-3 was produced by changing the alkali treatment conditions of Example 1-1 to the conditions described in Table 1.

  Comparative Example 1-4 was produced by changing the alkali treatment conditions of Example 1-1 to the conditions described in Table 1 and halving the film thickness of the low refractive index layer.

(Evaluation of film)
About the obtained film, the following items were evaluated. The results are shown in Table 1.

(Haze)
The total haze (H), internal haze (Hi), and surface haze (Hs) of the obtained film were measured by the following measurements.
[1] The total haze value (H) of the film obtained according to JIS-K7136 was measured.
[2] A few drops of silicone oil are added to the front and back surfaces of the obtained film on the low refractive index layer side, and sandwiched from the front and back using two 1 mm thick glass plates (micro slide glass product number S9111, made by MATSUNAMI) Then, the two glass plates and the obtained film are optically closely adhered, the haze is measured in a state where the surface haze is removed, and only silicone oil is sandwiched between the two glass plates separately measured. The value obtained by subtracting the measured haze was calculated as the internal haze (Hi) of the film.
[3] A value obtained by subtracting the internal haze (Hi) calculated in [2] from the total haze (H) measured in [1] was calculated as the surface haze (Hs) of the film.

(Friction band voltage)
The measurement sample is attached to a glass plate and left in advance in an environment of 25 ° C. and 55% RH for 2 hours or more. In the measurement, a cotton cloth was placed on the sample subjected to charge elimination at a pressure of 100 g / cm ² , and the charged voltage was monitored while only the sample was linearly reciprocated at 30 mm / sec. The charged voltage was the value measured at the 20th round-trip.

(Dust adhesion)
The measurement sample is attached to a glass plate and left in advance in an environment of 25 ° C. and 55% RH for 2 hours or more. After neutralizing the sample, the sample was rubbed back and forth 20 times with a becot, and a commercially available tissue paper was made fine and applied to the entire sample as simulated dust. Thereafter, the sample was set up vertically, the state of dust adhesion was observed, and the following evaluation was performed.
◎: Pseudo garbage falls more than 80% and is not noticeable ○: Pseudo garbage falls more than 50% and is not noticeable △: Pseudo garbage falls more than 50% and is slightly noticeable ×: Pseudo garbage falls more than 50% However, it is easy to stand out. XX: Pseudo dust remains on the sample surface more than 50% and is easily noticeable.

By treating a film containing a fluorine-containing compound in the uppermost layer on the transparent support under the conditions of the present invention, the frictional voltage when rubbing with a cotton cloth at 30 mm / sec can be within ± 500 V.
However, as can be seen from Table 1, even if the frictional voltage is within -500V to 500V, if the surface haze value is 0% or exceeds 10%, the pseudo dust falls more than 50%. Since it was conspicuous, it was evaluated that the dust adhesion was insufficient.

It is explanatory drawing of the one aspect | mode of the antireflection film of this invention.

Explanation of symbols

A Transparent support B Hard coat layer that also serves as an antiglare layer C Antireflection layer

Claims (4)

  The uppermost layer on the transparent support contains a fluorine-containing compound, has a haze value of 0.1% or more and 10% or less due to surface scattering, and has a frictional voltage of ± 500 V when rubbed with a cotton cloth at 30 mm / sec. An antireflection film characterized by being within.   The antireflection film according to claim 1, wherein the haze value resulting from internal scattering is 5 to 30%.   When a film containing a fluorine-containing compound in the uppermost layer on the transparent support is rubbed with a cotton cloth at 30 mm / sec by treating with an alkaline aqueous solution of 3 to 7 N at 40 to 80 ° C. for 2 to 5 minutes. A method for producing an antireflection film, characterized in that the frictional voltage of is within 500V.   An image display device comprising the antireflection film according to claim 1 or 2 on a display surface.

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