JP2001194522A - Optical film and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a good optical film having infrared absorbability, excellent in adhesion, high in twist, with a flat and smooth surface, with little curl, and good in surface quality, concerning an optical film used for a front filter or the like of a plasma display panel. SOLUTION: An optical film is produced by performing flow casting on a substrate dope containing an infrared adsorption dye having absorption in an infrared region and by peeling the dope, and by drying the dye.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical film that can be used for a display device such as a plasma display, and a front filter for a plasma display using the same.

[0002]

2. Description of the Related Art A front filter for a plasma display is required to have various functions such as near-infrared ray cutting performance, heat ray shielding performance, electromagnetic wave shielding performance, anti-scratch performance, and anti-reflection performance.

In particular, in a plasma display panel,
Since a large amount of electromagnetic waves and heat rays are emitted from the screen, the temperature of the panel surface becomes 80 to 100 ° C., and there is a risk of burns, the front filter of the plasma display panel has been required to have a function of shielding them. In addition to heat rays,
Near-infrared rays (wavelength: 800 to 1100 nm) are also emitted, which may cause a remote controller such as a home appliance to malfunction, and a countermeasure has been required. In addition to these infrared cut performances, in order to impart the various functions described above, for example, JP-A-11-167350, JP-A-11-66933, JP-A-11-65461, JP-A-11-65464,
There have been proposed various front filters having a laminated structure as described in JP-A-11-65462. However, such complex laminated structures are expensive to manufacture,
In addition, in a laminate formed by adhesion, the adhesion of the adhesion portion (the adhesion at the interface of each lamination) is poor, and this improvement has been demanded.

[0004]

SUMMARY OF THE INVENTION The present invention relates to an optical film used for a front filter or the like of a plasma display panel, which has an infrared absorbing property, is excellent in adhesion, has high flatness, and has a smooth surface. An object of the present invention is to provide an optical film having less curl and good surface quality.

[0005]

As a result of intensive studies, the present inventors have found that the above-mentioned problems can be solved by the following means.

(1) A method for producing an optical film, comprising casting a dope containing an infrared-absorbing dye having an absorption in the infrared region on a support, peeling the dope, and drying the film.

(2) In a method for producing an optical film in which at least two or more kinds of dopes are used and the dopes are simultaneously or sequentially cast on a support, peeled and dried, at least one dope is used. A method for producing an optical film, comprising an infrared absorbing dye having an absorption in an infrared region.

(3) In a method for producing an optical film, at least two or more kinds of dopes are used, and the dopes are simultaneously or sequentially cast on a support, peeled off, and dried to produce an optical film. An infrared-absorbing dye having absorption in the infrared region, wherein at least one dope used to form the internal region comprises at least one dope that forms the surface layer of the film and a dope that forms the internal region. A method for producing an optical film, comprising:

(4) The method for producing an optical film according to any one of (1) to (3), wherein the at least one dope contains an ultraviolet absorber.

(5) The method for producing an optical film according to any one of (1) to (4), further comprising a stretching step.

(6) A method for producing an optical film, wherein the resin film containing an infrared-absorbing dye is stretched and produced.

(7) A molded article of a thermoplastic resin containing an infrared absorbing dye is prepared to have a draw ratio in one direction of 1.0 to 2.0 times and a draw ratio in another direction of 2.3 to 7.0 times. A method for producing an optical film, comprising performing biaxial stretching film formation.

(8) An optical film produced by the method described in (1) to (7). (9) An optical film containing an infrared absorbing dye having absorption in an infrared region and an ultraviolet absorber.

(10) The optical film according to the above (9), wherein at least one surface contains an ultraviolet absorber and has an area containing an infrared absorbing dye therein.

(11) The above (8) to (10), wherein a plasticizer is contained in a region containing the infrared absorbing dye.
The optical film according to any one of the above.

(12) The infrared-absorbing dye is at least one of thiopyrylium squarylium dye, thiopyrylium croconium dye, pyrylium squarylium dye and pyrylium croconium dye. The optical film according to any one of (8) to (11).

(13) The thiopyrylium squarylium dye, thiopyrylium crokonium dye, pyrylium squarylium dye or pyrylium croconium dye is a compound represented by the following general formula (1): The optical film described in (1).

[0018]

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In the general formula (1), X represents a sulfur atom or an oxygen atom, R ₁ and R ₂ represent hydrogen and any monovalent group, and m and n represent 0, 1, 2, 3 or 4 Represents

(14) The above (8) to (1), wherein the infrared absorbing dye is a compound represented by the general formula (2).
The optical film according to any one of 1).

[0021]

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In the general formula (2), R ₁ , R ₂ , R ₃ ,
R ₄ , R ₅ and R ₆ each represent a monovalent substituent. l and m represent an integer of 0 to 4.

(15) A front filter for a plasma display comprising the optical film according to the above (8) to (14).

Hereinafter, the present invention will be described in detail. The present inventor has found that by including an infrared absorbing dye in the optical film itself as described above, it is possible to provide a film having a simple structure and excellent adhesion to the front panel.

That is, in the production by the solution casting method, a film having excellent flatness could be provided by incorporating the infrared absorbing dye into the dope itself. Furthermore, it was confirmed that by incorporating an ultraviolet absorbing agent together with the infrared absorbing dye, infrared absorbing properties could be stably obtained over a long period of time. The ultraviolet absorber may be contained in the same portion as the infrared absorbing dye, but more preferably, two or more dopes are used, the infrared absorbing dye is mainly contained inside the film, and the ultraviolet absorber is contained in the surface layer. It is more preferable that the configuration is as follows. In addition, it has been confirmed that it is preferable that the infrared absorbing dye and the plasticizer are contained together, because the infrared absorbing property is more stably maintained.

Here, the surface layer of the film refers to a region within 10 μm from the surface of the film, and the other portion is defined as an internal region of the film. In order to change the composition of the surface layer and the inner region of the film, a method of casting a film will be described later, but a method of sequentially or simultaneously casting dope solutions having different compositions can be used.

The composition of the surface layer or the inner layer of the film can be easily determined by shaving a surface of 10 μm with a cutter or the like, dissolving it in a solvent, and performing component analysis by gas chromatography, HPLC, or the like. Can decide.

The present invention also provides another embodiment.
That is, by stretching a molded article of a thermoplastic resin containing an infrared absorbing dye, an optical film having more excellent flatness and good adhesiveness could be provided.

A typical example of a dye capable of absorbing infrared rays is an organic dye. The infrared absorbing dye in the present invention is an organic dye having an absorption in an infrared region (800 nm to 1100 nm), preferably in a visible region or an infrared region. Organic dyes whose main absorption is in the infrared region through the region are preferable, and among them, there is substantially no absorption in the visible region, and the infrared dye (800 nm to 1
(100 nm). Many compounds are known as infrared absorbing dyes, and examples thereof include cyanine dyes and oxonol dyes. However, all of these dyes have the drawback that the absorption in the visible region is large, the decomposition product has a yellow absorption, the compound is relatively unstable and easily decomposed, and the cost is high.

The organic dye used in the present invention has substantially no absorption in the visible region and has an infrared region (800 nm to 11 nm).
00nm), any of those having an absorption at the thiopyrylium squarylium dye,
A dye selected from thiopyrylium croconium dye, pyrylium squarylium dye and pyrylium croconium dye, in particular, a compound represented by the general formula (1) and a compound represented by the general formula (2) may be used as the dye. preferable.

The optical film of the present invention is not particularly limited.
As the resin used in the optical film of the present invention, for example, polyethylene film, polypropylene film,
Cellophane, cellulose diacetate film, cellulose acetate butyrate film, cellulose acetate propionate film, cellulose acetate phthalate film, cellulose triacetate, cellulose nitrate and other cellulose esters or their derivatives, polyethylene terephthalate (PET) film , Polyethylene naphthalate, polyvinylidene chloride film, polyvinyl alcohol film, ethylene vinyl alcohol film, syndiotactic polystyrene film, polycarbonate film, norbornene resin film, polymethylpentene film, polyetherketone film, polyethersulfone film, polysulfone Film, polyetherketone Bromide films, polyamide films, fluorocarbon resin film, nylon film, polymethyl methacrylate film, there may be mentioned acrylic film or polyarylate films,
In the present invention, a cellulose triacetate film (TAC film), a cellulose ester film such as a cellulose acetate propionate film, and a polycarbonate (hereinafter abbreviated as PC) film, which can be formed by a casting method, are transparent, mechanical, It is preferable that properties and optical anisotropy do not exist. Among them, TAC film and PC film are particularly preferably used because of easy film forming property and excellent workability.

In the cellulose ester film according to the present invention, the cellulose ester is preferably a lower fatty acid ester. The lower fatty acid in the lower fatty acid ester of the cellulose ester means a fatty acid having 6 or less carbon atoms, for example, cellulose acetate, cellulose propionate, cellulose butyrate and the like are preferred examples of the lower fatty acid ester of cellulose. .

Further, in addition to the above, see JP-A-10-458.
04, 8-2311761, U.S. Pat.
Mixed fatty acid esters such as cellulose acetate propionate and cellulose acetate butyrate described in JP-A-9,052 and the like can be used.

Among the above descriptions, the lower fatty acid ester of cellulose which is particularly preferably used is cellulose triacetate.

Further, from the viewpoint of base strength, it is particularly preferable to use a polymerization degree of 250 to 400 and an amount of bound acetic acid of 54 to 62.5%, and more preferably an amount of bound acetic acid of 58 to 62.5%.
62.5% cellulose triacetate.

As the cellulose triacetate according to the present invention, either cellulose triacetate synthesized from cotton linter or cellulose triacetate synthesized from wood pulp can be used alone or in combination. If the releasability from the belt or drum becomes a problem, it is preferable to use a large amount of cellulose triacetate synthesized from cotton linter having good releasability from the belt or drum because the productivity is high.

When cellulose triacetate synthesized from wood pulp is mixed and used, the ratio of cellulose triacetate synthesized from cotton linter is preferably 40% by mass or more, and the effect of releasability becomes remarkable. Is more preferable, and it is most preferable to use it alone.

Depending on the properties of the resin, a method of forming a film by a solution casting method and a method of extruding the resin in a molten state by melt extrusion molding using an extruder or the like are possible, but a film having little optical anisotropy is possible. In order to obtain high film thickness accuracy and surface quality, it is more preferable to form a film by a solution casting method.

The optical film of the present invention has a thickness of 50 μm to 300 μm.
A film having a thickness of about μm is preferably used depending on the application.

Next, the organic dye capable of absorbing infrared light used in the present invention will be described. The infrared absorbing dye having an absorption in the infrared region (800 to 1100 nm) used in the present invention is not particularly limited as long as it can absorb infrared light.
Among them, it is desirable to use a thiopyrylium squarylium dye, a thiopyrylium croconium dye, a pyrylium squarylium dye or a pyrylium croconium dye, which has little absorption in the visible region and little yellowing due to decomposition products and the like.

These thiopyrylium squarylium dye, thiopyrylium croconium dye, pyrylium squarylium dye and pyrylium croconium dye are compounds having a thiopyrylium nucleus, a pyrylium nucleus and a squarylium nucleus, and a croconium nucleus.

The compound having a squarylium nucleus refers to 1-cyclobutene-2-hydroxy- in the molecular structure.
The compound having a 4-one and the compound having a croconium nucleus are compounds having 1-cyclopentene-2-hydroxy-4,5-dione in the molecular structure. Here, the hydroxy group may be dissociated.

These compounds are represented by the general formula (1)
Is preferably represented by In the general formula (1), X
Represents a sulfur atom or an oxygen atom, and R ₁ and R ₂ represent hydrogen and 1
M and n represent 0, 1, 2, 3 or 4;

The general formula (1) will be further described. Where:
R ₁ and R ₂ each represent a monovalent substituent. The monovalent substituent is not particularly limited, but may be an alkyl group (for example, a methyl group, an ethyl group, an isopropyl group, a t-butyl group, a methoxyethyl group, a methoxyethoxyethyl group, a 2-ethylhexyl group, a 2-hexyldecyl group) Benzyl group), aryl group (for example, phenyl group, 4-chlorophenyl group, 2,6
-Dimethylphenyl group and the like), more preferably an alkyl group, and particularly preferably a t-butyl group. R ₁ and R ₂ may form a ring together. m and n each represent an integer of 0 to 4, and preferably 2 or less.

The dyes represented by the general formula (1) used in the present invention are illustrated below, but the present invention is not limited to these dyes.

[0046]

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[0047]

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[0048]

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These dyes are disclosed in Japanese Patent Application No. 10-30949.
It can be produced by the production method described in No. 3.

In the present invention, the formula (2)
The croconium dye represented by formula (1) can be preferably used.

In the general formula (2), R ₁ , R ₂ , R ₃ ,
R ₄ , R ₅ and R ₆ each represent a monovalent substituent. l and m represent an integer of 0 to 4.

The substituents of the general formula (2) will be described in more detail. In the formula, the monovalent substituent represented by each of R ₁ , R ₂ , R ₃ , R ₄ , R ₅ and R ₆ is not limited, but may be an alkyl group (for example, a methyl group, an ethyl group, an isopropyl group, a t-group). −
Butyl group, methoxyethyl group, methoxyethoxyethyl group, 2-ethylhexyl group, 2-hexyldecyl group, benzyl group, etc., aryl group (for example, phenyl group, 4-
Chlorophenyl group, 2,6-dimethylphenyl group, etc.),
It is preferably a hydroxyl group or an acyl group (for example, an acetyl group), more preferably an alkyl group, an aryl group, or a hydroxyl group.
The above substituents, substituents having an ether bond and hydroxyl groups are preferred. Further, an alkyl group is most preferable. In particular, R ₁ , R ₂ , R
₃ and R ₄ are particularly preferably a substituent having 5 or more carbon atoms or a substituent having an ether bond because solubility in an organic solvent is improved. Further, R ₁ , R ₂ , R ₃ , R ₄ , R ₅ and R ₆ may form a ring together, for example, R ₁ ,
R ₂ and R ₅ may work together to form a julolidyl group.
l and m each represent an integer of 0 to 4, and 0 or 1 is preferable from the viewpoint of easy synthesis of the dye.

Hereinafter, specific examples of these dyes will be illustrated, but these dyes are not limited only to the specific examples.

[0054]

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[0055]

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[0056]

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These croconium dyes are disclosed in Japanese Patent Application No.
The compound can be easily synthesized by the method described in JP-A-236522.

The above dyes have substantially no absorption in the visible region, and are thus also preferably used as the dyes for use in the present invention.

The amount of the infrared absorbing dye to be used is not uniform depending on the kind of the compound and the conditions of use, but usually 0.01 g to ² g per 1 m ² of the optical film is preferably used.

Of these, those soluble in a solvent are more preferable because they can be uniformly added to the dope and formed into a film by a casting method, and those unnecessary for the solvent are dispersed as fine particles by the following method and added. It is also possible.

Further, in the present invention, it is preferable to add a plasticizer to the portion containing the infrared absorbing dye, so that the stability of the infrared absorbing dye can be improved and the adhesion is also improved.

As the plasticizer, a phosphoric acid ester or a carboxylic acid ester is preferably used. Phosphate esters include triphenyl phosphate (TPP) and tricresyl phosphate (TCP), biphenyl-diphenyl phosphate, dimethylethyl phosphate. Representative carboxylic esters include phthalic esters and citric esters. Examples of phthalic acid esters include dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), and dioctyl phthalate (DO).
P) and diethylhexyl phthalate (DEHP),
Ethylphthalylethyl glycolate and the like are used. Examples of citrate esters include acetyltriethyl citrate (OACTE) and acetyltributyl citrate (OACTE).
ACTB) is used. Examples of other carboxylic esters include butyl oleate, methylacetyl ricinoleate, dibutyl sebacate, and various trimellitic esters. Phthalate ester plasticizers (DMP,
DEP, DBP, DOP, DEHP) are preferably used, but not limited to these.

The amount of the plasticizer is preferably 1 to 20% by mass, more preferably 2 to 15% by mass in the film.
It is desirable to add it.

Further, a plasticizer having a freezing point of not more than 25 ° C. is preferably used because it gives flexibility to the film and helps the solubility of the infrared absorbing dye.

Further, by incorporating an ultraviolet absorber into the optical film of the present invention, an optical film having improved durability can be obtained. That is, by incorporating the ultraviolet absorbing agent in the layer containing the infrared absorbing dye, a more stable infrared absorbing effect can be maintained for a long period of time. In the case of a two-layer film, one layer may contain an infrared absorbing dye, and the other layer may contain an ultraviolet absorber. Further, in the case of a film having three or more layers, it is preferable that an infrared absorbing dye or an infrared absorbing dye and an ultraviolet absorber are contained in the inside of the film, and at least one surface layer contains an ultraviolet absorber. More preferably, an ultraviolet absorber can be contained in the surface layers on both sides.

The useful ultraviolet absorbers used in the present invention include salicylic acid derivative (UV-1), benzophenone derivative (UV-2), benzotriazole derivative (UV-3), acrylonitrile derivative (UV-4),
Benzoic acid derivative (UV-5) or organometallic complex salt (UV-
6) and the like, and (UV-1) includes phenyl salicylate, 4-t-tylphenyl salicylic acid, etc.
(UV-2) includes 2-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, and the like, and (UV-3) includes 2- (2′-hydroxy-
5'-methylphenyl) -benzotriazole, 2-
(UV-hydroxy-3'-5'-di-butylphenyl) -5-chlorobenzotriazole, etc.
4) As 2-ethylhexyl-2-cyano-3,
3'-diphenyl acrylate, methyl-α-cyano-
β- (p-methoxyphenyl) acrylate and the like,
V-5) includes resorcinol-monobenzoate, 2 ', 4'-di-t-butylphenyl-3,5-t
-Butyl-4-hydroxybenzoate and the like (UV-
Examples of 6) include nickel bis-octylphenylsulfamide, nickel salts of ethyl-3,5-di-t-butyl-4-hydroxybenzylphosphoric acid, and the like.

The above-mentioned ultraviolet absorber preferably used in the present invention is a benzotriazole-based ultraviolet absorber or benzophenone which has high transparency and is excellent in preventing deterioration of optical devices such as a polarizing plate, a liquid crystal element and a plasma display. UV absorbers are preferred, and benzotriazole UV absorbers with less unnecessary coloring are particularly preferred. Examples of the method for adding the ultraviolet absorbent additive liquid used in the present invention include the following methods.

(Addition Method A) As a method for preparing an ultraviolet absorber additive solution, an ultraviolet absorber is dissolved in an organic solvent such as alcohol, methylene chloride, or dioxolane, and then directly added to the dope composition.

(Addition method B) As a method for preparing an ultraviolet absorber additive liquid, an ultraviolet absorber and a small amount of a cellulose ester are dissolved in an organic solvent such as alcohol, methylene chloride, or dioxolane, and then added to the dope with an in-line mixer. .

The addition method B is preferable because the addition amount of the ultraviolet absorber can be easily adjusted, so that the productivity is excellent.

The amount of the ultraviolet absorber used is not uniform depending on the kind of the compound, the conditions of use and the like, but is usually preferably 0.1 g to 2.0 g, and more preferably 0.3 g to 2.0 g per 1 m ² of the optical film.
1.5 g is more preferable, and 0.5 g to 1.0 g is particularly preferable.

Further, fine particles (matting agent) can be added to the optical film of the present invention in order to impart surface slipperiness. As the fine particles, the following inorganic substances and / or organic substances are used alone or in an appropriate combination.

For example, examples of the inorganic particles include silicon oxide, titanium oxide, aluminum oxide, aluminum hydroxide, tin oxide, zinc oxide, calcium carbonate, barium sulfate, talc, kaolin, and calcium sulfate.
As the organic particles, acrylic resin, organic silicone resin, polystyrene, urea resin, formaldehyde condensate, polymethyl methacrylate resin, acrylic styrene resin, polymethyl methacrylate resin,
Silicone resin, polystyrene resin, polycarbonate resin, benzoguanamine resin, melamine resin,
A resin made of a polyolefin resin, a polyester resin, a polyamide resin, a polyimide resin, a polyfluoroethylene resin, or the like is used, but is not particularly limited thereto.

The fine particles of silicon dioxide according to the present invention include, for example, Aerosil R972, R974 and R81.
2, 200, 300, R202, OX50, TT600
Commercial products having a trade name such as (above, manufactured by Nippon Aerosil Co., Ltd.) can be used.

As the fine particles of zirconium oxide according to the present invention, those commercially available under the trade names such as Aerosil R976 and R811 (all manufactured by Nippon Aerosil Co., Ltd.) can be used.

As the organic compound, for example, polymers such as silicone resin, fluorine resin and acrylic resin are preferable, and among them, silicone resin is preferably used.

Among the silicone resins described above, those having a three-dimensional network structure are particularly preferable. For example, Tospearl 103, 105, 108, 120, 1
Commercial products having trade names such as Nos. 45, 3120 and 240 (all manufactured by Toshiba Silicone Co., Ltd.) can be used.

The volume average particle diameter of these particle powders is preferably 0.01 μm to 0.5 μm.
It is desirable that the ratio of addition be 0.01 to 0.5% by mass per solid content.

The slip property is expressed by a coefficient of kinetic friction. The coefficient of kinetic friction is a coefficient of kinetic friction between the front and back surfaces of the film, and may be 2 or less when measured according to JIS-K-7125 (1987). It is more preferably at most 1.5, more preferably at most 1.0, even more preferably at most 0.5. The dynamic friction coefficient can be reduced by increasing the amount of the matting agent added. The slip property is measured with a steel ball, and it is desired that the dynamic friction coefficient is 0.4 or less, preferably 0.2 or less.

Methods for preparing a dispersion of fine particles such as a matting agent include, for example, the following three types, but are not particularly limited thereto.

(Preparation Method A) After stirring and mixing the solvent and the fine particles, the mixture is dispersed with a disperser. This is used as a fine particle dispersion. The fine particle dispersion is added to the dope and stirred.

(Preparation method B) After stirring and mixing the solvent and the fine particles, the mixture is dispersed with a disperser. This is used as a fine particle dispersion. Separately, a small amount of resin is added to a solvent and dissolved by stirring. The fine particle dispersion is added thereto and stirred. This is used as a fine particle addition liquid. The fine particle addition liquid is sufficiently mixed with the dope liquid using an in-line mixer.

(Preparation Method C) A small amount of resin was added to a solvent,
Stir to dissolve. Fine particles are added thereto and dispersed by a disperser. This is used as a fine particle addition liquid. The fine particle addition liquid is sufficiently mixed with the dope liquid using an in-line mixer.

The preparation method A is excellent in dispersibility of the fine particles, and the preparation method C is excellent in that the fine particles hardly re-aggregate. Preparation method B is a preferable preparation method which is excellent in both the dispersibility of the fine particles and the difficulty of reaggregation of the fine particles.

(Dispersion Method) When the fine particles are mixed with a solvent and dispersed, the concentration of the fine particles is preferably 5 to 30% by mass, more preferably 10 to 25% by mass, and most preferably 15 to 20% by mass.

As the solvent used, ketones such as acetone and methyl ethyl ketone, and esters and alcohols such as methyl acetate and ethyl acetate are used. Particularly, lower alcohols are preferable, and methyl alcohol, ethyl alcohol, propyl alcohol, Examples thereof include isopropyl alcohol and butyl alcohol, but are not particularly limited thereto.

As the disperser, an ordinary disperser can be used. Dispersers can be broadly divided into media dispersers and medialess dispersers.

Examples of the media dispersing machine include a ball mill, a sand mill, a dyno mill and the like.

As the medialess disperser, there are an ultrasonic type, a centrifugal type, a high pressure type and the like. The high-pressure dispersing device is a device that creates a special condition such as a high shear or a high pressure state by allowing a composition in which fine particles and a solvent are mixed to pass through a thin tube at a high speed. When processing with a high-pressure dispersion device, for example,
When the maximum pressure condition inside the device is 10
It is preferably at least MPa. More preferably, 20
MPa or more. At that time, the maximum arrival speed is 100
Those which reach m / sec or more and those whose heat transfer rate reaches 418 kJ / hour or more are preferable.

The high-pressure dispersion apparatus as described above includes Micro
There is an ultra-high pressure homogenizer (trade name: Microfluidizer) manufactured by Fluidics Corporation or a Nanomizer manufactured by Nanomizer, and a homogenizer of the Manton-Gaulin type, such as a homogenizer manufactured by Izumi Food Machinery Co., Ltd., and a UHN- manufactured by Sanwa Machine Co., Ltd. 01 and the like.

In the case of a cellulose ester film, it can be produced by a method in which a dope solution, which is a resin solution containing the above-mentioned components, is cast on a support. Particularly, in order to produce films having different additive compositions in the surface layer and the inner layer, the following production method by co-casting is preferable.

For example, in the production of a cellulose ester laminated film having two or more layers according to the present invention, a dope solution obtained by dissolving a cellulose ester in a solvent, an infrared absorbing dye according to the present invention and a small amount of a cellulose ester are dissolved. For example, a UV absorber or the like is separately added in-line to a dope solution prepared by mixing (dispersing) the above solution with an in-line mixer and a dope solution in which the cellulose ester is dissolved. (Or separately co-casting a dope solution containing fine particles), and these are cast on a casting belt using a die slit having a plurality of slits (casting step). After removing part of the solvent (drying process on the casting belt), peel off the casting belt and dry the peeled film (film drying) By degree) to the optical film of the present invention is obtained.

The method for producing the cellulose ester laminated film of the present invention by co-casting will be further described with reference to the process charts shown in FIGS.

FIG. 1 is a process diagram showing an example of an apparatus for producing a cellulose ester laminated film of the present invention by co-casting. FIG. 2 is a sectional view of the slit die 6 in FIG.

A dope solution 1a is charged into a dope solution tank 1 for preparing a cellulose ester dope solution.
The infrared absorbing dye additive liquid tank 2 is charged with the infrared absorbing dye additive liquid 2a, and the dope liquid tank 3 is charged with the UV absorbent additive liquid 3a.

The dope solution 1a is sent to the in-line mixers 5a and 5b by the sending pumps 4b and 4c, and the infrared absorbing dye added solution 2a is sent to the in-line mixer 5a by the pump 4a. The dope solution 1a and the infrared absorbing dye addition solution 2a are sufficiently mixed by the in-line mixer 5a and sent to the slit 12 of the slit die 6.

Similarly, the dope solution 1a and the UV absorber additive solution 3a are sufficiently mixed by the in-line mixer 5b and sent to the slit 13 of the slit die 6.

The upper and lower surface layers from the slit die 6 are composed of a mixed solution of the dope solution 1a and the UV absorber additive solution 3a.
The middle layer is composed of the dope solution 1a and the infrared absorbing dye additive solution 2a.
Is co-cast from the casting port 11 in the state of a mixed solution of
It is cast on a casting belt 8 that moves more continuously. The cast cellulose ester dope layer consisting of three layers,
After drying, as a cellulose ester laminated film 10,
The roller 9 separates from the casting belt. This allows the infrared absorbing dye to be present in the inner region, with U
The cellulose ester film of the present invention containing a V absorbent is obtained.

Regarding the co-casting method according to the production method of the present invention, as described above, a simultaneous multi-layer casting method in which two or three layers are merged in a die having two or three slits, There are, for example, a sequential multi-layer casting method in which two or three layers are formed through different dies, and any of these methods may be used, and a multi-layer casting combining a sequential multi-layer casting and a simultaneous multi-layer casting. It may be a method.

In the present invention, the dope solution in which the resin is dissolved is defined as a solution in which a resin such as cellulose ester is used as a solvent.
In the dope solution, an additive such as a plasticizer can be added, and of course, other additives can be added if necessary. The concentration of the resin in the dope solution is preferably from 10 to 30% by mass, and more preferably from 18 to 20% by mass.

The solvents used in the present invention may be used alone or in combination. However, it is preferable to use a mixture of a good solvent and a poor solvent from the viewpoint of production efficiency. More preferably, a mixture of a good solvent and a poor solvent is used. The ratio is such that the good solvent is 70 to 95% by mass and the poor solvent is 5 to 30% by mass.

The good solvent and poor solvent used in the present invention include:
Those that dissolve the resin used alone are defined as good solvents, and those that swell or do not dissolve alone are defined as poor solvents. Therefore, depending on the amount of acetic acid bonded to the resin, a good solvent,
When the poor solvent changes, for example, when acetone is used as a solvent, the amount of bound acetic acid in the case of cellulose ester is 55%.
In this case, the solvent becomes a good solvent, and when the amount of bound acetic acid is 60%, the solvent becomes a poor solvent.

Examples of good solvents used in the present invention include organic halogen compounds such as methylene chloride and dioxolanes.

As the poor solvent used in the present invention, for example, methanol, ethanol, n-butanol, cyclohexane and the like are preferably used.

When the cellulose ester is cellulose acetate propionate, or when the cellulose triacetate is once cooled to -20 ° C. or lower to be dissolved, a mixed solvent of methyl acetate and acetone is preferably used.

In preparing the above-mentioned dope solution, as a method for dissolving the cellulose ester, a general method can be used, but a preferable method is to mix the cellulose ester with a poor solvent and wet or swell. Let
Further, a method of mixing with a good solvent is preferably used. At this time, under pressure, the method of heating at a temperature not lower than the boiling point of the solvent at room temperature and the solvent does not boil, and dissolving while stirring, in order to prevent the generation of a massive undissolved substance called gel or mamako, More preferred.

Pressurization may be performed by a method of injecting an inert gas such as nitrogen gas or by increasing the vapor pressure of the solvent by heating. Heating is preferably performed from the outside. For example, a jacket type is preferable because temperature control is easy.

The heating temperature after the addition of the solvent is preferably in the range of not less than the boiling point of the solvent used and not boiling the solvent, and is preferably set in the range of not less than 60 ° C. and from 70 to 110 ° C., for example. . The pressure is adjusted at the set temperature so that the solvent does not boil.

After the dissolution, the resin is taken out of the container while cooling, or is taken out of the container by a pump or the like, cooled with a heat exchanger or the like, and supplied for film formation. The cooling temperature at this time may be cooled to room temperature, but it is more preferable to cool to a temperature 5 to 10 ° C. lower than the boiling point and perform casting at that temperature because the dope viscosity can be reduced.

In the casting step, a belt-shaped or drum-shaped stainless steel mirror-finished support is preferably used. The temperature of the support in the casting step can be cast in a general temperature range of 0 ° C. to a temperature lower than the boiling point of the solvent, but casting on the support at 0 to 40 ° C. causes the dope to gel. It is preferable in terms of the peeling limit time. The peeling limit time refers to the time during which the cast dope remains on the support at the limit of the casting speed at which a transparent film having good flatness can be continuously obtained. It is preferable that the peeling limit time is short because the productivity is excellent.

The surface temperature of the support on the casting side is 0 to 40 ° C., and the temperature of the solution (dope) is 25 to 40 ° C.
The temperature of the solution (dope) is preferably higher than the temperature of the support, more preferably 60 ° C., and more preferably + 5 ° C. or higher. It is preferable that the temperature of the solution (dope) and the temperature of the support be higher, since the drying speed of the solvent can be increased. However, if the temperature is too high, foaming or flatness may be deteriorated.

A more preferred range of the temperature of the support is 20
~ 40 ° C, a more preferable range of the solution (dope) temperature is:
35-45 ° C.

The temperature of the support at the time of peeling should be 10 to 4
The temperature is preferably set to 0 ° C, more preferably 15 to 30 ° C, because the adhesion between the film and the support can be reduced.

In order for the cellulose ester film at the time of production to exhibit good flatness, the amount of residual solvent when peeled from the support is preferably from 10 to 80%, more preferably from 20 to 40%, or from 60 to 40%. 80%, particularly preferably 20 to 30%.

In the present invention, the amount of the residual solvent is defined by the following formula. Residual solvent amount = (mass before heat treatment−mass after heat treatment) / (mass after heat treatment) × 100% In addition, when measuring the amount of residual solvent, the heat treatment means that the film is heated to 115 ° C.
Represents that heat treatment is performed for one hour.

The peeling tension at the time of peeling the film from the support is usually 200 to 250 N / m. The peeling strength is determined by the amount of the additive (infrared dye and ultraviolet absorber, etc.) per unit weight of cellulose ester. The cellulose ester film of the present invention, which has a large content and is thinner than the conventional one, is likely to be wrinkled at the time of peeling, and thus it is preferable that the cellulose ester film be peeled at a peelable minimum tension of 170 N / m, more preferably. Means peeling with a minimum tension of 140 N / m.

In the step of drying the cellulose ester film, the film peeled from the support is further dried to reduce the residual solvent content to 3% by mass or less, more preferably 0.5% by mass or less. is there.

In the film drying step, a roll suspension method
A method of drying while transporting the film by a pin tenter method is preferably used. For display members, it is preferable to dry while maintaining the width by a pin tenter method in order to improve dimensional stability. In particular, it is particularly preferable to maintain the width where the amount of the residual solvent immediately after peeling from the support is large, since the effect of improving the dimensional stability is more exhibited. It is effective for The means for drying the film is not particularly limited, and is generally performed using hot air, infrared rays, a heating roll, a microwave, or the like. It is preferable to use hot air in terms of simplicity. It is preferable that the drying temperature is divided into three to five stages in the range of 40 to 150 ° C. and is gradually increased.
It is more preferable to carry out in the range of 140 ° C. in order to improve dimensional stability.

In the production of the optical film of the present invention, it is preferable that the film is peeled off after casting, and that the width is maintained by means such as a tenter so that high flatness can be maintained. This makes it possible to obtain an optical film that does not warp for a long time. The tenter is desirably applied with a residual solvent amount of 10 to 40% by mass.
More preferably, the content is 15 to 35% by mass. The amount of the residual solvent can be determined from the film containing the solvent by the method described above.

Further, the optical film produced by the method of the present invention has excellent optical isotropy, and an optical film having a retardation Rt in the film thickness direction of 100 nm or less defined by the following formula can be obtained. The following optical films can be obtained, and further, an optical film of 0 to 50 nm can be obtained, which is excellent. Further, the method of the present invention is also excellent in that a uniform retardation can be obtained.

Rt = ((Nx + Ny) / 2−Nz) × d In-plane retardation Ro defined by the following equation
Is also excellent in that ± 10 nm, preferably 5 nm can be obtained.

Ro = (Nx−Ny) × d (where Nx is the refractive index of the film in a direction parallel to the film forming direction, Ny is the refractive index of the film in a direction perpendicular to the film forming direction, and Nz is The refractive index of the film in the thickness direction and d represent the thickness (nm) of the film, respectively.) The retardation Rt or Ro is determined using an automatic birefringence meter KOBRA-21ADH (manufactured by Oji Scientific Instruments). The three-dimensional refractive index is measured at a wavelength of 590 nm in an environment of 23 ° C. and 55% RH, and Nx, Ny, and Nz are measured, whereby Rt and Ro can be calculated.

In another embodiment of the present invention, a thermoplastic resin such as polyester is melt-extrusion molded to produce an optical film, which is excellent in infrared absorptivity, curling, film peeling and the like. There was no problem, and an optical film with high durability and uniformity and good flatness could be obtained. This will be specifically described below.

When a thermoplastic resin such as polyester is used for the optical film of the present invention, the polyester constituting the polyester film is not particularly limited, but a dicarboxylic acid component and a diol component are used as main components. It is preferably a polyester having a film forming property.

The main components of the dicarboxylic acid component include terephthalic acid, isophthalic acid, phthalic acid, 2-6 naphthalenedicarboxylic acid, 2-7 naphthalenedicarboxylic acid, diphenylsulfondicarboxylic acid, diphenylether dicarboxylic acid, and diphenylethanedicarboxylic acid. , Cyclohexanedicarboxylic acid, diphenyldicarboxylic acid,
Examples thereof include diphenylthioether dicarboxylic acid, diphenyl ketone dicarboxylic acid, and phenylindane dicarboxylic acid. Further, as the diol component,
Ethylene glycol, propylene glycol, tetramethylene glycol, cyclohexane dimethanol, 2,
2-bis (4-hydroxyphenyl) propane, 2,2
-Bis (4-hydroxyethoxyphenyl) propane,
Bis (4-hydroxyphenyl) sulfone, bisphenol full orange hydroxyethyl ether, diethylene glycol, neopentyl glycol, hydroquinone, cyclohexanediol and the like can be mentioned.

Among polyesters containing these as main constituents, terephthalic acid and / or 2-6-naphthalenedicarboxylic acid and diol components as dicarboxylic acid components from the viewpoint of transparency, mechanical strength, dimensional stability and the like.
Polyesters containing ethylene glycol and / or diethylene glycol as the main constituent are preferred. Among them, polyethylene terephthalate or polyethylene 2-
Polyesters containing 6-naphthalate as a main component, copolymerized polyesters composed of terephthalic acid, 2-6-naphthalenedicarboxylic acid and ethylene glycol, and polyesters containing a mixture of two or more of these polyesters as a main component are preferable. . When the ethylene terephthalate unit (component) or the ethylene 2-6 naphthalene unit (component) is contained in an amount of 70% by mass or more with respect to the polyester, a film having excellent transparency, mechanical strength, dimensional stability, and the like can be obtained. Can be

The polyester constituting these polyester films may be further copolymerized with other copolymer components as long as the effects of the present invention are not impaired.
Other polyesters may be mixed. Examples of these include the above-mentioned dicarboxylic acid component and diol component, and polyesters composed thereof.

Examples of the polyester constituting the polyester film include an aromatic dicarboxylic acid having a sulfonate group or an ester-forming derivative thereof, a dicarboxylic acid having a polyoxyalkylene group or an ester-forming derivative thereof, and a diol having a polyoxyalkylene group. May be copolymerized. In view of the polymerization reactivity of the polyester and the transparency of the film, 5-sodium sulfoisophthalic acid,
2-sodium sulfoterephthalic acid, 4-sodium sulfophthalic acid, 4-sodium sulfo-2,6-naphthalenedicarboxylic acid and sodium salts thereof with other metals (for example, potassium, lithium and the like) and ammonium salts,
Compounds substituted with a phosphonium salt or the like or ester-forming derivatives thereof, such as polyethylene glycol, polytetramethylene glycol, polyethylene glycol-polypropylene glycol copolymers, and compounds that have been converted to carboxyl groups by oxidizing hydroxy groups at both ends thereof, etc. preferable. For the purpose of improving the heat resistance of the film, a bisphenol compound and a compound having a naphthalene ring or a cyclohexane ring can be copolymerized.

The polyester used in the present invention may contain an antioxidant. In particular, when the polyester contains a compound having a polyoxyalkylene group, the effects of the object of the present invention are remarkable. The type of the antioxidant to be contained is not particularly limited, and various antioxidants can be used. Examples thereof include antioxidants such as hindered phenol compounds, phosphite compounds, and thioether compounds. Can be. Above all, an antioxidant of a hindered phenol compound is preferred from the viewpoint of transparency.

The content of the antioxidant is usually from 0.01 to 2% by mass, preferably from 0.1 to 2% by mass, based on the polyester.
0.5% by mass.

The polyester film used in the present invention may be provided with lubricity as required. The means for imparting lubricity is not particularly limited, but a method of adding external particles for adding inert inorganic particles to the polyester, a method of depositing internal particles for depositing a catalyst to be added at the time of synthesis of the polyester, or a method such as a surfactant is used. A method of applying the composition to the surface is generally used.

The method for synthesizing the raw material polyester for the polyester film used in the present invention is not particularly limited, and it can be produced according to a conventionally known polyester production method. For example, a direct esterification method in which a dicarboxylic acid component is directly esterified with a diol component, first using a dialkyl ester as a dicarboxylic acid component,
A transesterification method can be used in which a transesterification reaction is carried out between this and a diol component, and this is heated under reduced pressure to remove excess diol component and thereby polymerize.
At this time, if necessary, a transesterification catalyst or a polymerization reaction catalyst may be used, or a heat stabilizer may be added. In addition, in each process at the time of synthesis, a coloring inhibitor, an antioxidant,
Crystal nucleating agents, slip agents, stabilizers, antiblocking agents, ultraviolet absorbers, viscosity modifiers, defoamers, clarifiers, antistatic agents, pH adjusters, dyes, pigments and the like may be added.

<Definition of Glass Transition Temperature Tg, Crystallization Temperature Tc and Melting Point Tm in the Present Invention> 10 mg of a film or a pellet was placed in a nitrogen stream of 300 ml / min.
Melt at 0 ° C. and immediately quench in liquid nitrogen. This quenched sample was subjected to a differential scanning calorimeter (DSC8, manufactured by Rigaku Denki Co., Ltd.).
230) and in a nitrogen stream at 100 ml / min.
The temperature is raised at a rate of 10 ° C. per minute, and Tg, Tc and Tm are detected. Tg is the temperature at which the baseline begins to shift,
Tc was the peak temperature of the exothermic peak, and Tm was the peak temperature of the endothermic peak. The measurement start temperature is determined by the Tg to be measured.
The temperature is lower by at least 50 ° C.

Next, a method for producing a polyester film will be described. The polyester film used in the present invention has a unidirectional stretching ratio of 1.0 to 2.0 times,
It is preferable that the polyester film is a biaxially stretched polyester film having a stretching ratio of 2.3 to 7.0 times in a direction perpendicular to the direction, and more preferably, a stretching ratio in the longitudinal direction of 1.0 to 1.0.
2.0 times, it is a polyester film biaxially stretched and formed with a transverse stretching ratio of 2.3 to 7.0 times, and more preferably a longitudinal stretching ratio of 1.1 to 1.8 times. And a biaxially stretched polyester film having a transverse stretching ratio of 3.0 to 6.0 times.

The polyester film can be obtained by a conventionally known method and is not particularly limited, but can be obtained by the following method. The longitudinal direction refers to the film forming direction (longitudinal direction) of the film, and the lateral direction refers to the direction perpendicular to the film forming direction.

First, the raw material polyester is formed into pellets, dried with hot air or vacuum, then the infrared absorbing dye of the present invention is added, mixed, kneaded, melt-extruded, and extruded from a T-die into a sheet. Then, it is brought into close contact with a cooling drum by an electrostatic application method or the like, and cooled and solidified to obtain an unstretched sheet.

Next, the obtained unstretched sheet was subjected to a heating operation such as a plurality of roll groups and / or an infrared heater to determine the glass transition temperature (Tg) of the polyester as Tg + 1.
This is a method in which the film is heated to a temperature within the range of 00 ° C. and longitudinally stretched in one or more stages. In the present invention, the stretching ratio in the longitudinal direction is 1.0 to
The range is preferably 2.0 times, more preferably 1.1 to 1.8 times.

Next, the polyester film stretched in the machine direction obtained as described above was subjected to Tg-Tm-20 ° C.
In the temperature range described above, the film is stretched in the transverse direction and then heat set. In the present invention, the stretching ratio in the transverse direction is preferably in the range of 2.3 to 7.0 times, more preferably 3.0 to 6.0.
It is more preferably in the range of 4.0 to 6.0 times.

In the case of lateral stretching, it is preferable to carry out lateral stretching while sequentially increasing the temperature in the range of 1 to 50 ° C. in the stretching region divided into two or more portions, because the distribution of physical properties in the width direction can be reduced.
Further, after the transverse stretching, the film is maintained at a temperature of not lower than the final transverse stretching temperature and at a temperature of not less than Tg-40 ° C. for 0.01 to 5 minutes.

The heat setting is performed at a temperature higher than the final transverse stretching temperature and in a temperature range of Tm-150 ° C. to Tm-25 ° C., usually for 0.5 to 300 seconds. The heat setting temperature is more preferably in the temperature range of Tm-140 ° C to Tm-60 ° C, and still more preferably in the temperature range of Tm-130 ° C to Tm-70 ° C. At this time, it is more preferable to heat-fix while sequentially increasing the temperature in the range of 1 to 100 ° C. in the two or more divided regions.

The heat-fixed film is usually cooled to Tg or less, cut off the clip holding portions at both ends of the film, and wound up. At this time, within a temperature range of not more than the final heat setting temperature and not less than Tg, 0.1 to 1 in the horizontal and / or vertical directions.
It is preferable to perform a 0% relaxation treatment. Further, it is preferable that the cooling is gradually performed from the final heat setting temperature to Tg at a cooling rate of 100 ° C. or less per second. The means for cooling and relaxing treatment is not particularly limited, and can be performed by a conventionally known means. In particular, it is preferable to perform these treatments while sequentially cooling in a plurality of temperature regions from the viewpoint of improving the dimensional stability of the film. The cooling rate is a value obtained by (Tl-Tg) / t, where Tl is the final heat setting temperature and t is the time required for the film to reach the Tg from the final heat setting temperature.

Since the most optimal conditions of the heat setting, cooling and relaxation treatment conditions vary depending on the polyester constituting the film, the physical properties of the obtained biaxially stretched film are measured and adjusted appropriately so as to have preferable characteristics. It should just be determined by doing.

In the production of the film, a functional layer such as a clear coat layer, an antistatic layer, a slippery layer, an adhesive layer, and a barrier layer may be applied before and / or after stretching. At this time, various surface treatments such as a corona discharge treatment, a plasma discharge treatment, and a chemical treatment can be performed as necessary. The clip gripping parts at both ends of the cut film are
After being pulverized or, if necessary, subjected to granulation, depolymerization, re-polymerization, or the like, it may be reused as a raw material for the same type of film or as a raw material for a different type of film.

In the present invention, the polyester film stretched and formed in only one direction can be obtained by performing only one direction in the biaxial stretching film formation. The stretching direction may be either the vertical direction or the horizontal direction, but more preferably, the film is stretched only in the horizontal direction. In this case, the stretching ratio is preferably in the range of 2.3 to 7.0 times, more preferably in the range of 3.0 to 6.0 times, and still more preferably in the range of 4.0 to 6.0 times. is there. Regarding the refractive index in the plane direction of the polyester film formed as described above, the difference nTD-nMD between the horizontal refractive index (nTD) and the vertical refractive index (nMD) is 0.03 or more. It is preferably 0.04 or more, more preferably 0.05 or more.

In the present invention, the polyester film formed as described above preferably has a heat shrinkage of 5% or less in both the vertical and horizontal directions at 80 ° C. for 30 minutes. More preferably, the heat shrinkage is 2% or less in both the vertical and horizontal directions,
More preferably, it is 1% or less.

In the case of a polyester optical film,
Thicknesses of about 50 to 300 μm are used, and preferably 60 to 200 μm.

The polyester film used in the present invention has a T
g is preferably 50 ° C. or higher, more preferably 60 ° C. or higher. Tg is determined as an average value of a temperature measured by a differential scanning calorimeter at which a baseline starts to be shifted and a temperature at which the baseline returns to a new baseline.

The optical film of the present invention preferably has a conductive surface, and has a surface resistivity (23 ° C., 25% R
H) is preferably 1 × 10 ¹² Ω / □ or less. More preferably, it is 1 × 10 ¹¹ Ω / □ or less, and further preferably, it is 1 × 10 ¹⁰ Ω / □ or less.

The method for imparting conductivity to the film is not particularly limited, but it can be formed by incorporating a hygroscopic substance or a conductive substance. Examples of the substance imparting conductivity include a surfactant, a conductive polymer, and an inorganic metal oxide.

Examples of the surfactant that can be used include:
Any of anionic, cationic, amphoteric and nonionic may be used. Examples of the anionic surfactant include alkyl carboxylate, alkyl sulfonate, alkyl benzene sulfonate, alkyl naphthalene sulfonate, alkyl sulfate, alkyl phosphate, N-acyl-N-alkyltaurine Acid groups such as carboxy, sulfo, phospho, sulfate, and phosphate groups such as sulfosuccinates, sulfoalkylpolyoxyethylene alkylphenyl ethers, and polyoxyethylene alkyl phosphates. Is preferred.

Examples of the cationic surfactant include alkylamine salts, aliphatic or aromatic quaternary ammonium salts, heterocyclic quaternary ammonium salts such as pyridinium and imidazolium, and phosphonium or aliphatic or heterocyclic containing heterocyclic rings. Sulfonium salts and the like are preferred.

As the amphoteric surfactant, for example, amino acids, aminoalkylsulfonic acids, aminoalkylsulfuric acid or phosphoric acid esters, alkylbetaines, amine oxides and the like are preferable.

Examples of the nonionic surfactant include saponin (steroid type), alkylene oxide derivatives (eg, polyethylene glycol, polyethylene glycol / polypropylene glycol condensate, polyethylene glycol alkyl ethers or polyethylene glycol alkyl aryl ethers, polyethylene glycol ester) , Polyethylene glycol sorbitan esters, polyalkylene glycol alkylamines or amides, polyethylene oxide adducts of silicone), glycidol derivatives (eg, alkenyl succinic acid polycerides, alkylphenol polyglycerides),
Alkyl esters such as polyhydric alcohol fatty acid esters are preferred.

The conductive polymer is not particularly limited, and may be any of anionic, cationic, amphoteric and nonionic. Among them, preferred are anionic and cationic. More preferred are sulfonic acid-based and carboxylic acid-based polymers for anionic and tertiary amine-based and quaternary ammonium-based polymers or latex for cationic.

These conductive polymers include, for example, anionic polymers or latexes described in JP-B-52-25251, JP-A-51-29923, JP-B-60-48024, JP-B-57-18176 and JP-B-57-176176. 560
No. 59, 58-56856, U.S. Pat.
8,231 and the like.

The optical film of the present invention may be provided with a clear hard coat layer on the surface, if necessary, to improve the scratch resistance. For this reason, a coating composition containing an actinic ray-curable resin (for example, an ultraviolet-curable resin) or a thermosetting resin can be applied. May be coarse. However, since the optical film of the present invention has excellent flatness and small surface roughness, even when a clear hard coat layer is provided, good flatness can be obtained on the surface thereof.

In particular, an example of an actinic ray-curable resin layer for clear hard coat processing will be described. The actinic ray-curable resin layer refers to a layer mainly composed of a resin which is cured by a cross-linking reaction or the like by irradiation with actinic rays such as ultraviolet rays or electron beams. Typical examples of the actinic ray-curable resin include an ultraviolet ray-curable resin and an electron beam-curable resin. Examples of the ultraviolet-curable resin include an ultraviolet-curable acrylic urethane-based resin, an ultraviolet-curable polyester acrylate-based resin, an ultraviolet-curable epoxy acrylate-based resin, an ultraviolet-curable polyol acrylate-based resin, and an ultraviolet-curable epoxy resin. I can do it.

The UV-curable acrylic urethane-based resin is
In general, a product obtained by reacting an isocyanate monomer or a prepolymer with a polyester polyol is further added with 2-hydroxyethyl acrylate and 2-hydroxyethyl methacrylate (hereinafter, only acrylate is shown as including methacrylate). It can be easily obtained by reacting an acrylate monomer having a hydroxyl group such as 2-hydroxypropyl acrylate (see, for example,
-151110).

The UV-curable polyester acrylate resin can be easily obtained by reacting a polyester polyol with 2-hydroxyethyl acrylate or 2-hydroxy acrylate monomer (for example, JP-A-59-151112). ).

As a specific example of the ultraviolet-curable epoxy acrylate resin, epoxy acrylate is used as an oligomer, and a reactive diluent and a photoreaction initiator are added to the oligomer to cause a reaction. Kaiping 1
No.-105738). As the photoreaction initiator, one or more of a benzoin derivative, an oxime ketone derivative, a benzophenone derivative, and a thioxanthone derivative can be selected and used.

Specific examples of the ultraviolet-curable polyol acrylate resin include trimethylolpropane triacrylate, ditrimethylolpropane tetraacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, and alkyl-modified dipentane. Erythritol pentaacrylate and the like can be mentioned. These resins are usually used together with a known photosensitizer. Further, the above-mentioned photoreaction initiator can also be used as a photosensitizer. Specifically, acetophenone, benzophenone,
Examples thereof include hydroxybenzophenone, Michler's ketone, α-amyloxime ester, tetramethyluram monosulfide, thioxanthone and the like, and derivatives thereof. When an epoxy acrylate photoreactive agent is used, a sensitizer such as n-butylamine, triethylamine, tri-n-butylphosphine and the like can be used. The photoreaction initiator or photosensitizer contained in the ultraviolet-curable resin composition excluding the solvent component volatilized after coating and drying is preferably used in an amount of 1 to 10% by mass of the composition.

Examples of the resin monomer include, as one monomer having an unsaturated double bond, methyl acrylate,
Examples include general monomers such as ethyl acrylate, butyl acrylate, vinyl acetate, benzyl acrylate, cyclohexyl acrylate, and styrene. As monomers having two or more unsaturated double bonds, ethylene glycol diacrylate, propylene glycol diacrylate, divinylbenzene, 1,4-
Examples thereof include cyclohexane diacrylate, 1,4-cyclohexyldimethyl adiacrylate, the above-mentioned trimethylolpropane triacrylate, and pentaerythritol tetraacryl ester.

The solid content of the coating composition for the actinic radiation-curable resin layer is preferably from 10 to 95% by mass, and an appropriate concentration is selected depending on the coating method.

As a light source for forming a cured film layer of the actinic ray-curable resin by a photocuring reaction, any light source that generates ultraviolet rays can be used. For example, a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a carbon arc lamp, a metal halide lamp, a xenon lamp, and the like can be used. Irradiation conditions differ depending on each lamp, but the irradiation light amount is 20 to 10000 mJ / c.
sufficient if degree m ^2, preferably, 50～2000MJ
/ Cm ² . From the near-ultraviolet region to the visible light region, it can be used by using a sensitizer having an absorption maximum in that region.

The solvent used for coating the actinic ray-curable resin layer is as follows:
Solvents for coating the resin layer described above, for example, hydrocarbons, alcohols, ketones, esters, glycol ethers, and other solvents can be appropriately selected or mixed and used.

As a method of applying the coating liquid for the ultraviolet curable resin composition, known methods such as a gravure coater, a spinner coater, a wire bar coater, a roll coater, a reverse coater, an extrusion coater, and an air doctor coater can be used. The coating amount is 0.1 in wet film thickness.
1 to 30 μm is suitable, preferably 0.5 to 15 μm
It is. The coating speed is preferably 10 to 100 m / min
Done in

After the ultraviolet curable resin composition is applied and dried, ultraviolet light is irradiated from a light source. The irradiation time is preferably 0.5 seconds to 5 minutes. Seconds to 2 minutes are more preferred.

Further, the optical film of the present invention may be provided with an antistatic layer, an antireflection layer, and an easily adhesive layer.

The optical film of the present invention can be subjected to a corona discharge treatment or a plasma discharge treatment in order to modify the surface, whereby the wettability of the coating liquid can be improved,
Adhesion can be further improved. In addition, a metal or metal oxide thin film for shielding electromagnetic waves and cutting off heat rays can be provided by plasma treatment.

The optical film of the present invention is superior in the infrared cut performance to a plasma display panel filter as compared with a conventionally known transparent resin material in which an infrared shielding layer is applied by coating, and has a film peeling property. It has excellent curl characteristics and durability, and can be manufactured at low cost.

By using this as a filter for a plasma display panel, it is possible to suppress malfunction of other devices that use light in the near-infrared region, to suppress heating of the plasma display panel itself, and to use it as a filter for a plasma display panel. A useful optical film having high durability can be obtained.

[0172]

EXAMPLES The present invention will be described below in detail with reference to examples, but the present invention is not limited to these embodiments.

Example 1 Each dope containing the components shown in Table 1 was prepared.

[0174]

[Table 1]

CAP: Cellulose acetate propionate Degree of acetyl substitution 2.0 Degree of propionyl substitution 0.8 Number average molecular weight 100,000 TAC: Cellulose triacetate Average degree of acetylation 61% UV absorber A: Tinuvin 109 (Chivas Specialty Chemicals) 0.8 kg Tinuvin 117 (manufactured by Ciba Specialty Chemicals KK) 0.8 kg Plasticizer B: 11 kg of triphenyl phosphate Plasticizer C: 8 kg of triphenyl phosphate 3 kg of ethylphthalylethyl glycolate Infrared Absorbing dye D: Exemplified compound 1-1 Infrared absorbing dye E: Exemplified compound 2-1 Fine particles F: Aerosil 200V (manufactured by Nippon Aerosil Co., Ltd.) 0.1 kg Fine particles G: Aerosil R972 (manufactured by Nippon Aerosil Co., Ltd.) 0 .1 kg of each dope In manufacturing, the infrared absorbing dye was added to ethanol 10kg dissolution. When adding fine particles,
An ethanol solution in which fine particles were dispersed was added thereto. The remaining ethanol and the other materials constituting the dope were charged into a closed container, kept at 80 ° C. under pressure, completely dissolved with stirring, and then filtered to prepare each dope.

First, the prepared dope 3 was cooled to 33 ° C.
, And uniformly cast on a stainless steel band, and dried at 33 ° C. for 5 minutes. After peeling off from the stainless steel band, a tenter was performed so that the stretching ratio was 1.01 to 1.05 times while the residual solvent amount was 35% by mass to 10% by mass. Further, drying was completed while being conveyed by a large number of rolls, and an optical film 1 shown in Table 2 was obtained.

Of dopes 1 to 7 prepared in the same manner, dope 2 and dope 7 were used to produce optical films 6 and 7 shown in Table 2, respectively.

Similarly, a co-casting liquid was melted at a temperature of 33 ° C. and a width of 1500 mm by a simultaneous multi-layer casting method using a belt casting apparatus to form a two-layer structure by merging in a die having two slits. In the order of the first layer (dope 7) and the second layer (dope 6) from the belt side, the solid content of the dope 7 is 40 μm and the solid content of the dope 6 is 40 μm.
The solution was uniformly cast on a stainless steel band to a thickness of μm and dried at 33 ° C. for 5 minutes. After peeling from the stainless steel band, a tenter was performed so that the residual solvent amount was 30% by mass to 10% by mass and the stretching ratio was 1.01 to 1.05 times. Further, the drying was completed while being conveyed by a number of rolls, and an optical film 5 shown in Table 2 was obtained.

Similarly, using the belt casting apparatus, dope 1
The co-casting liquid is joined at a temperature of 33 ° C. and a width of 1500 mm on a stainless steel casting belt by a simultaneous multilayer casting method in which the dope 2 is joined in a die having three slits so as to sandwich the dope 2 into a three-layer structure. From the side, the first layer (dope 1), the second layer (dope 2), and the third layer (dope 1) in this order have a dry film thickness of 20 μm for dope 1 and dope 2 for dope 2
Was uniformly cast on a stainless steel band so as to be 40 μm, and dried at 33 ° C. for 5 minutes. After peeling from the stainless steel band, a tenter was performed so that the residual solvent amount was 30% by mass to 10% by mass and the stretching ratio was 1.01 to 1.05 times. Further, the drying was completed while being conveyed by a number of rolls, and an optical film 2 shown in Table 2 was obtained.

The optical film 3 of Table 2 was prepared in the same manner except that the dope 3 was sandwiched by the dope 1.
I got

Further, an optical film 4 shown in Table 2 was obtained in the same manner except that the dope 5 was sandwiched by the dope 4.

A comparative optical film 1 was prepared as follows using the dope 1 shown in Table 1 prepared by the above-described method.

The dope 1 was cooled and maintained at 33 ° C., and was uniformly cast on a stainless steel band of a belt casting apparatus and dried at 33 ° C. for 5 minutes. After peeling off from the stainless steel band, a tenter was performed so that the stretching ratio was 1.01 to 1.05 times while the residual solvent amount was 35% by mass to 10% by mass. Further, drying was completed while being conveyed by a large number of rolls, and a film having a dry film thickness of 80 μm was obtained.

The following composition was applied by reverse roll coating on the surface which was the stainless steel band side (surface B side) at the time of casting of this film to provide a coating layer having a dry film thickness of 10 μm. It was set to 1.

(Coating composition) Diacetyl cellulose 1.0 kg Infrared absorbing dye H 0.1 kg Ethyl acetate 50 kg Acetone 32 kg Isopropyl alcohol 4 kg

[0186]

Embedded image

The optical films 1 to 5 of the present invention obtained above were obtained.
7. The comparative optical film 1 was evaluated according to the following method.

(A) Measurement of curl value After leaving the film sample for 48 hours in an environment of 23 ° C. and 55% RH, the film is cut into a longitudinal direction (film forming direction) of 2 mm and a width direction of 50 mm. Further, the small piece of the film is humidified in an environment of 23 ± 2 ° C. and 55% RH for 24 hours, and a radius of curvature corresponding to a circumference having a curve matching the film is confirmed using a curvature scale. Radius (1
/ M) was taken as the curl value of the film (for example, when the curl of the film is 10 (1 / m), it means that the curvature is the same as the curve of the circumference of a circle having a radius of 0.1 m).

(B) Roll Soil After an optical film of 10,000 m was prepared, the degree of soiling of the first roll in contact with the film peeled from the stainless steel band support was visually observed and evaluated according to the following ranks.

(Evaluation Criteria) ロ ー ル: The roll is not dirty at all ○: A very small part of the roll is slightly stained △: The roll is slightly stained entirely ×: The roll is completely stained (C) Cross-cut adhesion test (adhesion) Adhesion was evaluated according to the cross-cut adhesion test described in 4.15 of JIS D0202.

That is, 6.15 of JIS K5400
100 squares (1 mm width) on the test surface
× 10), a cellophane adhesive tape (18 mm width) described in JIS Z 1522 was completely adhered on the grid, and immediately one end of the tape was kept at a right angle to the test surface, instantly separated, and completely peeled off I checked the number of grids left without.

(Evaluation Criteria) A: Not peeled at all B: Peeled area ratio was less than 10% C: Peeled area ratio was less than 10 to 30% D: Peeled area (D) Durability test After irradiating the sample with an ultraviolet intensity of 100 mW / cm ² for 50 hours, it was left in a room at 23 ° C. and 55% RH for 24 hours.
This sample was checked for coloring.

Ultraviolet irradiation condition: I-Super UV tester manufactured by Iwasaki Electric Co., Ltd. SUV-F1 Light source Metal halide lamp Ultraviolet intensity 100 mW / cm ² Irradiation time 50 hours Sample temperature 20 ° C. (Evaluation standard) ：: No discoloration is observed. Discolored to pale yellow △: Discolored to yellow

[0194]

[Table 2]

Example 2 An optical film was produced using a polyester film as follows.

(Production of PET film) 100 parts by mass of dimethyl terephthalate, 65 parts by mass of ethylene glycol,
To 2 parts by weight of diethylene glycol, 0.05 parts by weight of magnesium acetate hydrate was added as a transesterification catalyst, and a transesterification reaction was performed according to a conventional method. To the obtained product, 0.05 parts by mass of antimony trioxide and 0.03 parts by mass of trimethyl phosphate were added. Then, the temperature was gradually increased and the pressure was reduced, and polymerization was carried out at 280 ° C. and 0.5 mmHg to obtain polyethylene terephthalate having an intrinsic viscosity of 0.70, a melting point (Tm) of 261 ° C., and a glass transition temperature (Tg) of 76 ° C.

Further, this polyethylene terephthalate was vacuum-dried at 150 ° C. for 8 hours, and then heated to melt.
Further, as the infrared absorbing dye, 1-
1 was added, mixed, kneaded, melt-extruded at 285 ° C. using an extruder, and brought into close contact with a cooling drum at 30 ° C. while applying static electricity, and cooled and solidified to obtain an unstretched sheet. This unstretched sheet was stretched 1.2 times in the machine direction at 85 ° C. using a roll-type longitudinal stretching machine. The temperature difference between the front and back surfaces was within 5 ° C.

The obtained uniaxially stretched film was stretched 4.5 times in the transverse direction at 95 ° C. using a tenter type transverse stretching machine.
Next, heat treatment is performed at 70 ° C. for 2 seconds.
Heat set at 80 ° C. for 25 seconds. Next, at 150 ° C., the film is relaxed in the transverse (width) direction and wound up to a length of 15 mm in the transverse direction.
A biaxially stretched polyethylene terephthalate (PET) film having a thickness of 00 mm and a thickness of 40 μm was produced. This was used as an optical film 8.

A PET film was prepared in the same manner except that the infrared absorbing dye 1-1 was omitted. Next, the following composition was applied to this film by reverse roll coating to provide a coating layer having a dry film thickness of 10 μm.

(Coating Composition) Polymethyl methacrylate 1.0 kg Infrared absorbing dye H 0.1 kg Methyl ethyl ketone 50 kg Propylene glycol monomethyl ether 36 kg The above-mentioned optical film 8 of the present invention and comparative optical film 2 were prepared as described above. The curl and adhesion were evaluated according to the following.

[0201]

[Table 3]

According to the results shown in Table 3, it was confirmed that the optical film 8 was less curled than the comparative optical film 2 and was excellent in adhesion.

[0203]

The present invention has high infrared absorption useful as an optical film used for a front filter for a plasma display, has excellent flatness, has little curl, has good film adhesion, has high durability, and has high productivity. And an inexpensive optical film and a method for producing the same were obtained.

[Brief description of the drawings]

FIG. 1 is a process diagram showing an example of an apparatus for producing a laminated film by co-casting according to the present invention.

FIG. 2 is a cross-sectional view of a slit die used in a co-casting manufacturing apparatus of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Dope liquid tank 1a Dope liquid 2 Infrared absorbing dye additive liquid tank 2a Infrared absorbing dye additive liquid 3 Tank 3a UV absorbent additive liquid 4a Pump 4b Pump 4c Pump 4d Pump 5a Inline mixer 5b Inline mixer 6 Slit die 7 Drum 8 Casting belt 9 Roller 10 Cellulose ester laminated film 11 Casting port 12 Slit 13 Slit

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G09F 9/00 313 G09F 9/00 313 5G435 // C08J 5/18 CEP C08J 5/18 CEP CER CER CEZ CEZ CEZ C09K 3/00 105 C09K 3/00 105 B29K 101: 12 B29K 101: 12 B29L 11:00 B29L 11:00 (72) Inventor Toshiaki Shibue 1, Sakuracho, Hino-shi, Tokyo In-house (72) Inventor Toshiyuki Hagiwara Konica Stock Company, Fukushima Term, 1 Sakura-cho, Hino-shi, Tokyo (Reference) BC01 4F205 AA01 AB12 AB14 AC05 AG01 AG03 AH73 GA07 GB02 GC07 GE02 GE24 GF 01 GF02 GF21 GF24 GN22 GN29 GW21 4F210 AA24 AB06 AB07 AB12 AB14 AB19 AG01 AH33 AH73 QA02 QA03 QC06 QG01 QG18 4J002 AB021 BB031 BB121 BB161 BC021 BD101 BD121 BE021 BG051 EB001 EL03 001 001 001 001 EV306 EW048 EZ007 FD028 FD057 FD096 GP00 5G435 AA00 AA07 BB06 GG11 GG16 GG32 HH02 KK07 KK10

Claims (15)

[Claims] 1. A method for producing an optical film, comprising: casting a dope containing an infrared-absorbing dye having an absorption in an infrared region on a support, peeling the dope, and drying the film. 2. Use of at least two or more dopes,
After simultaneously or sequentially casting the dope on a support, in a method for producing an optical film produced by drying after peeling,
A method for producing an optical film, characterized in that at least one dope contains an infrared absorbing dye having absorption in an infrared region. 3. Use of at least two or more dopes,
In a method for producing an optical film, which is produced by simultaneously or sequentially casting the dope on a support, peeling the film, and then drying the film, the dope used to form the surface layer of the film is used.
An optical film comprising at least one kind of dope and a dope for forming an internal region, wherein at least one dope used for forming the internal region contains an infrared absorbing dye having an absorption in an infrared region. Manufacturing method. 4. The method according to claim 1, wherein the at least one dope contains an ultraviolet absorber.
Item 13. The method for producing an optical film according to item 9. 5. The method for producing an optical film according to claim 1, further comprising a stretching step. 6. A method for producing an optical film, comprising stretching a resin film containing an infrared absorbing dye. 7. A molded article of a thermoplastic resin containing an infrared-absorbing dye is stretched to a stretch ratio of 1.0 to 2.0 times in one direction and 2.3 to 7.0 times in another direction. A method for producing an optical film, comprising forming a film by axial stretching. 8. An optical film produced by the method according to claim 1. 9. An optical film comprising an infrared absorbing dye having absorption in an infrared region and an ultraviolet absorber. 10. The optical film according to claim 9, wherein at least one surface contains an ultraviolet absorber and has a region containing an infrared absorbing dye therein. 11. The optical film according to claim 8, wherein a plasticizer is contained in a region containing the infrared absorbing dye. 12. The method according to claim 1, wherein the infrared absorbing dye is at least one of a thiopyrylium squarylium dye, a thiopyrylium croconium dye, a pyrylium squarylium dye and a pyrylium croconium dye. The optical film according to any one of 8 to 11, wherein 13. A thiopyrylium squarylium dye,
13. The optical film according to claim 12, wherein the thiopyrylium croconium dye, pyrylium squarylium dye or pyrylium croconium dye is a compound represented by the following general formula (1). Embedded image [In the general formula (1), X represents a sulfur atom or an oxygen atom; R ₁ and R ₂ represent hydrogen and any monovalent group;
n represents 0, 1, 2, 3, or 4. ] 14. The optical film according to claim 8, wherein the infrared absorbing dye is a compound represented by the general formula (2). Embedded image [In the general formula (2), R ₁ , R ₂ , R ₃ , R ₄ , R ₅ and R ₆ each represent a monovalent substituent. l and m represent an integer of 0 to 4. ] 15. A front filter for a plasma display, comprising the optical film according to claim 8. Description: