TWI435901B - A cellulose ester film, a method for producing the same, a polarizing plate using a cellulose ester film, and a display device - Google Patents

Description

Cellulose ester film, method for producing the same, polarizing plate using cellulose ester film, and display device

The present invention relates to a cellulose ester which can be used for a protective film for a polarizing plate, a retardation film, a viewing angle expansion film, an antireflection film used for a plasma display, and the like, which are used for a liquid crystal display device (LCD). A film, a method for producing the same, a polarizing plate using a cellulose ester film, and a display device.

In recent years, liquid crystal display devices have been used in televisions or large monitors due to improvements in image quality or high-definition technology, and in particular, the size of such liquid crystal display devices has been reduced, or the cost of efficiency production has been reduced. It is strongly expected that the material of the liquid crystal display device is also remarkably enhanced, and the widening of the optical film is desired.

In addition, in recent years, in response to the rapid growth of liquid crystal TVs, the demand for optical films has also steadily increased, and productivity has been strongly sought. Regarding the cellulose ester film formed by the solution casting method, in the film film, the amount of the solvent to be dried is only small, so that the production speed can be improved.

By obtaining a film having a wide width by a solution casting method, it is possible to widen the casting width on a cast-molded support such as a rotary-driven stainless steel endless belt or a drum.

On the one hand, the width of the cast-cast support or the cast-cast mold has an upper limit due to limitations in the manufacture of the device. In the case of a cast-iron support, the upper limit of the width is now recognized as 2000 mm. In this case, the casting ceiling is limited. It is safe to be around 1900mm at the time of taking into account the snakes when the belt is conveyed. Further, even if the cast support is a metal drum, the maximum width is about 2,500 mm due to the same manufacturing restrictions. In the case of film forming of a magnetic drum, since gelation by cooling is self-supporting in the cast film, it is necessary to form a film in the portion to be cooled, and the end portion has a temperature change due to heat release and cannot be used. The cast casting width is around 2000mm.

Because of the limitation in the manufacture of any kind of equipment, the width of the casting is limited. Therefore, in the current situation, it is considered that the film after casting is stretched so that the film width is as wide as possible, and a film having a wide width can be obtained. In the method of stretching a film after casting, a film having a wide width is known, and it is known that PET or polyvinyl alcohol is stretched by about 2 to 4 times with respect to the width of the casting, and a film having a wide width can be obtained.

However, in the case of a cellulose ester film, the rigidity of the molecular structure is considered to be high until the elongation rate cannot be increased. In the following Patent Documents 1 and 2, it is proposed to stretch the cellulose ester film to 1.2 times.

Patent Document 1 discloses that the amount of residual solvent is less than 120% by mass, the temperature is 115° C. or more, and when it is 160° C. or less, the stretching is 1.2 to 4.0 times. Further, Patent Document 2 discloses that the temperature difference between the film passing portions is 0° C. or higher, and in the constant temperature bath at 4° C. or lower, when the temperature is from room temperature to 160° C., the stretching is 1.2 times or more and 1.8 times or less. .

[Patent Document 1] JP-A-2002-71957 (Patent Document 2) JP-A-2002-131540

However, in the production method described in Patent Documents 1 and 2, the haze of the cellulose ester is increased, and the transmittance of light is lowered, so that there is a problem that the contrast is lowered when it is incorporated in the display device. Next, we believe that this problem is due to the unreasonable force applied to the film during stretching.

SUMMARY OF THE INVENTION The object of the present invention is to provide a solution which solves the above-mentioned problems in the prior art. In the stretching step of the web, the web is stretched in the broad direction to 1.2 times or more and the haze is not high. A method for producing an ester film, a cellulose ester film produced by the method, a polarizing plate of a cellulose ester film, and a display device.

In order to achieve the above object, the invention of claim 1 is a resin solution containing a cellulose ester resin, which is cast into a cast support to form a cast film, which is dried to make the solvent in the cast film into a cast film. In the peelable state, after the stripping support is peeled off, the both ends of the peeled web are subjected to a stretching step of stretching in the width direction, the solvent is dried, and the cellulose ester film is obtained by winding. In the method for producing a cellulose ester film, the stretching ratio of the web in the stretching step is 20 to 60%, and the temperature of the warm air ejected from the warm air blowing means in the stretching step is relative to the film after winding. The glass transition temperature (Tg) is characterized by Tg + 35 ° C ~ Tg + 80 ° C.

The invention of claim 2, in the method for producing a cellulose ester film according to claim 1, enters the film before the stretching step The amount of the residual solvent is 10 to 35 mass%.

The invention of claim 3 is the method for producing a cellulose ester film according to claim 1 or 2, which has an organic component other than the solvent contained in the exhaust air sent to the self-stretching step. The removal means is characterized by it.

According to the invention of claim 4, in the method for producing a cellulose ester film according to the third aspect of the patent application, the exhaust air of the organic component is removed, and the stretching step is again used as one of the upstream drying winds. Re-use is characterized by it.

The invention of claim 5 is the method for producing a cellulose ester film according to item 4 of the patent application, wherein the means for removing is characterized by a plurality of connections.

The invention of claim 6 is the cellulose ester film produced by the method of any one of claims 1 to 3, wherein the width of the film after winding is 1650 to 2500 mm.

The invention of claim 7 is the cellulose ester film of claim 6 in which the film thickness of the film after winding is 40 to 80 μm.

The invention of the polarizing plate of claim 8 of the patent application is characterized in that the cellulose ester film of claim 6 or 7 is used on one side.

The invention of the display device of claim 9 is characterized in that the cellulose ester film of claim 6 or 7 is used.

According to the invention of claim 1, the resin solution containing the cellulose ester resin is casted into the cast support to form a cast film, and dried to make the solvent in the cast film into a peelable state. After the self-flow casting support is peeled off, the both ends of the peeled web are subjected to a stretching step of stretching in the width direction to dry the solvent, and the cellulose ester film obtained by winding to obtain a cellulose ester film is manufactured. In the method, the elongation ratio of the mesh in the stretching step is 20 to 60%, and the temperature of the warm air is sprayed from the warm air spraying means in the stretching step, and the glass transition temperature (Tg) of the film after winding In the case of Tg+35°C~Tg+80°C, according to the invention of the first application of the patent application, even if the film is stretched at a high level, the haze of the film does not become high, and optical properties capable of producing transparency and excellent planarity can be achieved. The effect of the ester film.

The invention of claim 2, in the method for producing a cellulose ester film according to the first aspect of the patent application, the amount of residual solvent of the film before entering the stretching step is 10 to 35 mass%, according to the patent application scope. According to the invention of the second aspect, it is possible to ensure an appropriate self-supporting property while reducing the stress acting on the film.

When the temperature of the stretching step is increased in the present invention, the amount of volatilization of an organic component such as a plasticizer tends to increase, and according to the invention of claim 3, the exhaust gas having a self-stretching step is provided. The organic component contained therein is removed, so that contamination of the film by the organic component or contamination of the film manufacturing apparatus can be prevented. Further, according to the fourth item of the patent application, the stretching step is again reused as one of the upstream drying winds, so that the production cost of the cellulose ester film can be reduced.

The invention of claim 5 is the method for producing a cellulose ester film according to item 4 of the patent application, wherein the removing means is a plurality of connectors, and the invention can be exhausted according to the invention of claim 5 The concentration of the organic component in the wind is indeed reduced, so that the exhaust air can be effectively reused again by the stretching step as part of the upflowing dry wind.

In the cellulose ester film produced by the method of any one of the first to third aspects of the patent application, the width of the film after winding is 1650 to 2500 mm, according to The invention of claim 6 of the patent application can achieve the effect of producing a wide cellulose ester film for a liquid crystal display device.

The invention of the cellulose ester film of claim 7 is a film thickness of 40 to 80 μm after winding, and according to the invention of claim 7 of the patent application, it is possible to contribute to the thinning of the display device. effect.

According to the invention of the polarizing plate of the eighth aspect of the patent application, even when it is incorporated in the liquid crystal display device, the contrast is not lowered, and the effect of excellent visibility can be achieved.

According to the invention of the display device of claim 9 of the patent application, the reduction in contrast is not caused, and the effect of excellent visibility can be achieved.

[Best form of implementing the invention]

Next, an embodiment of the present invention will be described, but the present invention is not limited to these.

The present invention relates to a resin solution (doping) containing a cellulose ester resin, which is cast into a cast casting branch by a rotary drive of an endless belt made of stainless steel or a magnetic drum. The cast film is formed into a body and dried so that the solvent in the cast film becomes a peelable state after the cast film is peeled off. After the strip casting support is peeled off, the both ends of the peeled web are pulled in the width direction. Extending the stretching step, drying the solvent, and obtaining a cellulose ester film by winding, in the method for producing a cellulose ester film by a solution casting method, the elongation ratio of the web in the stretching step It is 20 to 60%, and the temperature of the warm air sprayed from the warm air spraying means in the stretching step is Tg + 35 ° C to Tg + 80 ° C with respect to the glass transition temperature (Tg) of the film after winding.

In the stretching step of the present embodiment, the both sides of the mesh (or film) are stretched by a clip or the like, and the warm air ejection means is a warm air ejection slit of the stretcher. .

In the present embodiment, the resin solution (doping) containing the cellulose ester resin contains at least one of a plasticizer, a retardation modifier, an ultraviolet absorber, fine particles, and a low molecular weight substance, and a cellulose ester resin. , with solvent.

Hereinafter, this will be described in detail.

The cellulose ester is a cellulose ester substituted with a thiol group or the like from a hydroxyl group of cellulose. For example, cellulose acetate, cellulose triacetate, cellulose acetate propionate, cellulose acetate butyrate, cellulose acetate propionate butyrate, etc. Or cellulose acetate having an aliphatic polyester grafted side chain or the like. Among them, cellulose acetate having cellulose acetate, cellulose acetate propionate, and aliphatic polyester grafted side chain is preferred. Other substituents may also be included in the range which does not inhibit the effects of the present invention.

In the case of cellulose triacetate, the degree of substitution with ethyl hydrazide is 2.0 or more and 3.0 or less are preferred. When the degree of substitution is within this range, good formability can be obtained, and the in-plane retardation (R0) and the thickness direction retardation (Rt) can be obtained. When the degree of substitution of the acetyl group is lower than this range, the heat resistance of the retardation film is particularly deteriorated in dimensional stability under moist heat, and when the degree of substitution is too large, it may not be necessary. The case of delay characteristics.

The cellulose of the raw material of the cellulose ester used in the present invention is not particularly limited, and examples thereof include cotton pulp wood pulp, kenaf, and the like. Further, the cellulose esters obtained from these can be used in combination at any ratio.

In the present invention, the number average molecular weight of the cellulose ester is in the range of 60,000 to 300,000, and the mechanical strength of the obtained film is preferably strong. Further, 70,000 to 200,000 is preferred.

In the present specification, an organic solvent having good solubility with respect to a cellulose ester film is referred to as a good solvent, and exhibits a main effect on dissolution, and a solvent widely used therein is referred to as a main solvent or a main solvent.

Examples of the good solvent include ketones such as acetone, methyl ethyl ketone, cyclopentanone, and cyclohexanone, tetrahydrofuran (THF), 1,4-dioxane, and 1,3-dioxolane. (dioxolane), ethers of 1,2-dimethoxyethane, etc., other than esters of methyl formate, ethyl formate, methyl acetate, ethyl acetate, amyl acetate, γ-butyrolactone, etc. , there are still methyl cellosolve, dimethyl imidazolidinone, dimethylformamide, dimethylacetamide, acetonitrile, dimethyl hydrazine, sulfolane, nitroethane, Methylene chloride, acetamethyleneacetate methyl or the like is preferred, and 1,3-dioxolane, THF, methyl ethyl ketone, acetone, methyl acetate and dichloromethane are preferred.

In the dopant, in addition to the above organic solvent, it is preferred to contain 1 to 40% by mass of an alcohol having 1 to 4 carbon atoms. After casting the doping stream into the cast support, the solvent is allowed to evaporate to increase the ratio of the alcohol, so that the mesh (the doping of the cellulose derivative on the cast support) can be cast. Gelatinized as a mesh in the future, as a mesh, to make the mesh firm, and can be used as a gelling solvent which is easy to peel off the castable support. When the ratio is small, There is also a role in promoting the dissolution of the cellulose ester resin caused by the non-chlorine organic solvent.

The alcohol having 1 to 4 carbon atoms may, for example, be methanol, ethanol, n-propanol, isopropanol, n-butanol, secondary butanol, tertiary butanol or propylene glycol monomethyl ether. Among these, it is excellent in the stability of doping, the boiling point is also low, and the drying property is also good, and it is preferable that ethanol is not toxic. These organic solvents are not soluble in the cellulose derivative alone and may be referred to as a weak solvent.

A cellulose ester resin which is an appropriate polymer compound which satisfies such a condition is preferably a solvent which is dissolved in a high concentration solvent, and the ratio of dichloromethane to ethyl alcohol is 95:5 to 80:20. Solvent. Or a mixture of methyl acetate: ethyl alcohol 60: 40 ~ 95: 5 can also be used as appropriate.

In the present invention, the film can be combined to impart workability to the film. Softness. A moisture-proof plasticizer, a fine particle (matting agent) which imparts lubricity to a film, an ultraviolet absorber which imparts an ultraviolet absorbing function, an antioxidant which prevents deterioration of a film, and the like, and can be blended with various additives.

In the aspect of the plasticizer used in the present invention, the cellulose ester tree can be caused by the haze occurring in the film or the bleed out or volatilization from the film. The polycondensate of the reactive metal compound which is lipid or hydrolyzed and polycondensed is preferably a functional group which interacts by hydrogen bonding or the like.

The functional group may, for example, be a hydroxyl group, an ether group, a carbonyl group, an ester group, a carboxylic acid residue, an amine group, an imino group, a decylamino group, a guanidino group, a cyano group, a nitro group, a sulfonyl group or a sulfonate group. The acid residue, the phosphonium group, the phosphonic acid residue and the like are preferably a carbonyl group, an ester group or a phosphonium group.

As an example of such a plasticizer, a phosphate ester plasticizer, a phthalate plasticizer, a 1,2,4-benzenetricarboxylate plasticizer, a pyromellitic acid plasticizer, and a polyvalent alcohol ester plasticity can be suitably used. Agent, glycolic acid ester plasticizer, citric acid ester plasticizer, fatty acid ester plasticizer, carboxylate plasticizer, polyester plasticizer, etc., especially polyvalent alcohol ester plasticizer, hydroxyl A non-phosphate ester plasticizer such as an acetate-based plasticizer or a polyvalent carboxylate-based plasticizer.

The polyvalent alcohol ester is formed from an ester of a divalent or higher aliphatic polyvalent alcohol and a monocarboxylic acid, and preferably has an aromatic ring or a cycloalkyl ring in the molecule. This polyvalent alcohol is as shown in the following general formula (1).

General formula (1) R1-(OH)n (However, R1 represents an organic group of n valence, and n represents a positive integer of 2 or more)

Examples of suitable polyvalent alcohols include, for example, the following, but the present invention is not limited thereto.

Examples of suitable polyvalent alcohols include exemplified adonitol, arabitol, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propane Alcohol, 1,3-propanediol, dipropylene glycol, tripropylene Alcohol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, dibutylene glycol, 1,2,4-butanetriol, 1,5-pentane Alkanediol, 1,6-hexanediol, hexanetriol, galactitol, mannitol, 3-methylpentane-1,3,5-triol, tetramethylethylene Pinacol, sorbitol, trimethylolpropane, trimethylolethane, xylitol, and the like. In particular, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, sorbitol, trimethylolpropane, xylitol are preferred.

The monocarboxylic acid to be used for the polyvalent alcohol ester is not particularly limited, and a known aliphatic monocarboxylic acid, alicyclic monocarboxylic acid, aromatic monocarboxylic acid or the like can be used. When an alicyclic monocarboxylic acid or an aromatic monocarboxylic acid is used, the moisture permeability is improved, and the retention is preferred.

Examples of suitable monocarboxylic acids include the following, but the invention is not limited thereto.

In the case of an aliphatic monocarboxylic acid, a fatty acid having a linear or side chain having 1 to 32 carbon atoms can be suitably used. The number of carbons is preferably from 1 to 20, and more preferably from 1 to 10. When acetic acid is contained, it is preferable to increase the compatibility with the cellulose ester resin, and it is preferred to use acetic acid in combination with other monocarboxylic acids.

Examples of suitable aliphatic monocarboxylic acids include acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, heptanoic acid, caprylic acid, capric acid, n-decanoic acid, 2-ethyl-hexanecarboxylic acid, Undecanoic acid, lauric acid, tridecanoic acid, myristic acid, pentadecanoic acid, palmitic acid, heptadecanoic acid, stearic acid, nineteen acid, twenty acid, behenic acid, tetracosic acid, two Saturated fatty acid such as hexadecanoic acid, twenty-seven acid, octadecanoic acid, thirty-carbonic acid, tridecanoic acid, undecylenic acid, oleic acid, sorbic acid, linoleic acid, linolenic acid, peanut diced acid Such as unsaturated fatty acids.

As an example of a suitable alicyclic monocarboxylic acid, a cyclopentanecarboxylic acid, a cyclohexanecarboxylic acid, a cyclooctanecarboxylic acid, or the like can be exemplified.

Examples of a suitable aromatic monocarboxylic acid include benzoic acid, tolyl mercapto acid, etc., which are introduced into an alkyl group in a benzene ring of benzoic acid, a biphenylcarboxylic acid, a naphthalenecarboxylic acid, and a tetrahydronaphthalenecarboxylic acid. The aromatic monocarboxylic acid having two or more benzene rings, or the like, is preferably benzoic acid.

The molecular weight of the polyvalent alcohol ester is not particularly limited, and is preferably from 300 to 1,500, more preferably from 350 to 750. It is preferable that the molecular weight is large because it is difficult to volatilize, and it is preferable that it is small in terms of moisture permeability and compatibility with the cellulose ester resin.

The carboxylic acid to be used for the polyvalent alcohol ester may be one type or a mixture of two or more types. Further, the OH group in the polyvalent alcohol can be completely esterified, so that a part of the OH group remains as it is.

The glycolic acid ester-based plasticizer is not particularly limited, and a glycolic acid ester plasticizer having an aromatic ring or a cycloalkyl ring in the molecule can be suitably used. As the appropriate glycolic ester plasticizer, for example, butyl phthalyl butyl hydroxyacetate, ethyl phthalic acid ethyl hydroxyacetate, methyl phthalyl phenyl acetate can be used. Hydroxyacetate and the like.

In the phosphate ester plasticizer, triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, diphenyl biphenyl phosphate, trioctyl group can be used. Phosphate, tributyl phosphate, etc., in the phthalate plasticizer, diethyl phthalate, dimethoxyethyl phthalate, dimethyl phthalate, Dioctyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate, dicyclohexyl Benzoate and the like.

These plasticizers can be used singly or in combination of two or more.

The amount of the plasticizer used is preferably from 1 to 20% by mass. It is preferably 6 to 16% by mass, and particularly preferably 8 to 13% by mass.

In the cellulose ester resin of the present invention, in order to impart lubricity, it is preferred to add fine particles such as a matting agent. The microparticles may, for example, be fine particles of an inorganic compound or fine particles of an organic compound.

Examples of the fine particles of the inorganic compound include fine particles such as cerium oxide, titanium oxide, aluminum oxide, zirconium oxide, and tin oxide. Among them, fine particles of a compound containing a ruthenium atom are preferred, and ruthenium dioxide fine particles are particularly preferred. As the cerium oxide microparticles, for example, AEROSIL 200, 200V, 300, R972, R972V, R974, R202, R812, R805, OX50, TT600, etc. manufactured by Aerosil Co., Ltd. may be mentioned.

Examples of the fine particles of the organic compound include fine particles such as an acrylic resin, a polyoxyxylene resin, a fluorine compound resin, and an urethane resin.

The primary particle diameter of the fine particles is not particularly limited, and the average particle diameter in the film is preferably about 0.05 to 5.0 μm. Further preferably, it is 0.1 to 1.0 μm.

The average particle diameter of the fine particles is an average value of the length of the long axis direction of the particles in the observation site of the film when the cellulose ester film is observed by an electron microscope or an optical microscope. The particles observed in the film may be primary particles, or secondary particles in which primary particles are agglomerated, and the plurality of particles generally observed are secondary particles.

The dispersion of the fine particles is preferably carried out by treating the composition in which the fine particles are mixed with the solvent in a high-pressure dispersion device. The high-pressure dispersing device is a device that mixes fine particles and a solvent, and passes through a thin tube at a high speed to produce a special condition such as a high shear or high pressure state.

In the above-mentioned high-pressure dispersing device, for example, an ultrahigh pressure homogenizer (trade name: Microfluidizer) manufactured by Microfluidics Corporation or a Nanomizer manufactured by Nanomizer Co., Ltd., and others may also be exemplified by Manton-Gaulin type high pressure dispersion. A device such as a homogenizer manufactured by Izumi Food Machinery.

In the present invention, the fine particles are dispersed in a solvent containing 25 to 100% by mass of a lower alcohol, and then mixed with a dopant dissolved in a solvent of the cellulose ester resin.

Here, the content ratio of the lower alcohol is preferably from 50 to 100% by mass, and more preferably from 75 to 100% by mass.

Further, as an example of the lower alcohol, methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol or the like is preferable.

The solvent other than the lower alcohol is not particularly limited, and a solvent used for film formation using a cellulose ester is preferred.

In the case of various optical films such as a polarizing plate protective film, a retardation film, and an optical compensation film, it is preferable to contain an ultraviolet absorber from the viewpoint of deterioration prevention.

In the ultraviolet absorber, the absorption energy of ultraviolet rays having a wavelength of 370 nm or less is excellent from the viewpoint of preventing deterioration of the polarizing element or the liquid crystal, and the wavelength is 400 nm or more from the viewpoint of liquid crystal display properties. It is better to absorb less light.

In the present embodiment, examples of the ultraviolet absorber to be used include a hydroxydiphenylketone compound, a benzotriazole compound, a salicylate compound, a diphenylketone compound, and a cyanoacrylate. A compound, a nickel-salted salt compound or the like is preferred, and a benzotriazole-based compound having less coloration is preferred. The ultraviolet absorber described in Japanese Laid-Open Patent Publication No. Hei 8-337574, and the polymer ultraviolet absorber described in JP-A-6-148430 can also be suitably used.

Specific examples of useful ultraviolet absorbers include 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-3', 5'-di- Tertiary butylphenyl)benzotriazole, 2-(2'-hydroxy-3'-tertiarybutyl-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-3 ',5'-di-tertiary butylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3'-(3",4",5",6"-tetrahydroortene Benzomethylene imine methyl)-5'-methylphenyl)benzotriazole, 2,2-methylenebis(4-(1,1,3,3-tetramethylbutyl)- 6-(2H-benzotriazol-2-yl)phenol, 2-(2'-hydroxy-3'-tertiary butyl-5'-methylphenyl)-5-chlorobenzotriazole, 2 -(2H-benzotriazol-2-yl)-6-(linear and side chain dodecyl)-4-methylphenol, octyl-3-[3-tert-butyl-4-hydroxy- 5-(Chloro-2H-benzotriazol-2-yl)phenyl]propionate with 2-ethylhexyl-3-[3-tert-butyl-4-hydroxy-5-(5-chloro- A mixture of 2H-benzotriazol-2-yl)phenyl]propionate or the like is not limited thereto.

Further, as a commercially available product of the ultraviolet absorber, Tinuvin (TINUVIN) 109, Tinuvin (TINUVIN) 171, and Tinuvin (TINUVIN) 326 (all manufactured by Chiba Specialty Chemicals Co., Ltd.) can be suitably used.

Further, in the present invention, a diphenyl ketone type which is obtained by using an ultraviolet absorber Specific examples of the compound include 2,4-dihydroxydiphenyl ketone, 2,2'-dihydroxy-4-methoxydiphenyl ketone, and 2-hydroxy-4-methoxy-5- Sulfodiphenyl ketone, bis(2-methoxy-4-hydroxy-5-phenylnonylphenylmethane), etc., but is not limited thereto.

In the present invention, the amount of the ultraviolet absorber is preferably 0.01 to 10% by mass, more preferably 0.1 to 5% by mass based on the cellulose ester (cellulose derivative). When the amount of the ultraviolet absorber used is too small, the ultraviolet absorbing effect may be insufficient. When the amount of the ultraviolet absorbing agent is too large, the transparency of the film may be deteriorated, which is not preferable. The ultraviolet absorber is preferably one having a high thermal stability.

In addition, the ultraviolet absorber of the ultraviolet ray absorbing agent of the present invention can be used as the ultraviolet absorbing agent described in JP-A-6-148430 and JP-A-2002-47357 (or UV absorbing property). polymer). In the general formula (1), or the general formula (2) described in JP-A-6-148430, or the general formula (3) (6) (7) described in JP-A-2002-47357. The polymer ultraviolet absorber can be suitably used.

The antioxidant is generally referred to as an anti-deterioration agent, but is preferably contained in a cellulose ester film as an optical film. In other words, when the liquid crystal display device or the like is placed in a high-humidity and high-temperature state, the cellulose ester film as an optical film may be deteriorated. The antioxidant may be contained in the film by, for example, a halide in a residual solvent in a film or a phosphoric acid of a phosphate-based plasticizer, etc., so that the decomposition of the film is delayed or prevented.

In the case of such an antioxidant, it is preferred to use a hindered phenol-based compound, for example, 2,6-di-tertiary butyl-p-cresol, pentaerythritol-four [3-(3,5-di) -Tris-butyl-4-hydroxyphenyl)propionate], triethylene glycol-bis[3-(3-tri-butyl-5-methyl-4-hydroxyphenyl)propionate], 1,6-hexanediol-bis[3-(3,5-di-tri-butyl-4-hydroxyphenyl)propionate], 2,4-bis(n-octylthio)-6 -(4-hydroxy-3,5-di-tertiary butylanilino)-1,3,5-three , 2,2-thio-di-ethylenebis[3-(3,5-di-tri-butyl-4-hydroxyphenyl)propionate], octadecyl-3-(3,5-di -Tris-butyl-4-hydroxyphenyl)propionate, N,N'-hexylene bis(3,5-di-tri-butyl-4-hydroxy-hydrocinnamylamine), 1,3, 5-trimethyl-2,4,6-tris(3,5-di-tri-butyl-4-hydroxybenzyl)benzene, three-(3,5-di-tertiary butyl-4 -Hydroxybenzyl)-trimeric isocyanate or the like. Especially 2,6-di-tertiary butyl-p-cresol, pentaerythritol-four [3-(3,5-di-tri-butyl-4-hydroxyphenyl)propionate] Triethylene glycol-bis[3-(3-tri-butyl-5-methyl-4-hydroxyphenyl)propionate] is preferred.

Further, for example, a metal inert agent such as N,N'-bis[3-(3,5-di-tris-butyl-4-hydroxyphenyl)propanyl]anthracene or the like may be used in combination (3). , phosphorus-based processing stabilizer such as 4-di-tertiary butylphenyl phosphite.

Hereinafter, embodiments of the cellulose ester film of the present invention will be described in detail. The film can be produced by a solution casting method.

Fig. 1 is a flow chart showing a specific example of an apparatus for carrying out a method for producing a cellulose ester film by a solution casting method. Further, in the practice of the present invention, it is not limited to the process of the drawings shown below.

First, in a dissolution boiler not shown, a cellulose ester resin is dissolved in a mixed solvent of a good solvent and a weak solvent, and the above-mentioned plasticizer or ultraviolet absorber is added thereto to prepare a resin solution (dopant).

In Fig. 1, the dopants adjusted by the dissolving boiler, for example, through a pressurized quantitative gear pump, are fed to the casting mold (2) by a conduit, and the casting position on the casting belt (1) is carried out. The self-flow mold (2) casts the doping stream. The cast-in-belt (1) corresponds to the cast-cast support of the present invention, and is an endless belt made of stainless steel which is rotationally driven and infinitely moved.

In the flow casting of the dopant caused by the flow molding die (2), there is a doctor balde method of adjusting the film thickness of the doped film (mesh) by the flow molding, or reverse rotation. The method of the roller adjustment reverse roller coater or the like is preferable, and the slit shape of the metal lid portion can be adjusted to make the film thickness easy to be a uniform pressurizing mold. In the press mold, there is a coat hanger mold or a T die, and the like can be suitably used.

The cast belt (1) is supported between the pair of drums, and the intermediate upper portion and the lower portion are supported from the inner side by a plurality of rollers (not shown).

One side of the drum of the rewinding portion at both ends of the cast belt (1), or both, is provided with a driving device for imparting the tension of the cast belt (1), whereby the cast belt (1) is subjected to tension and tension Full state use.

Further, in the present embodiment, after the winding, the width of the film is ensured to be 1650 to 2500 mm, the flow-casting bandwidth is 2000 to 2500 mm, and the casting width of the cellulose ester solution is 1900 to 2480 mm. Thereby, a cellulose ester film for a liquid crystal display device having a wide width can be produced by a cast molding method.

Here, the width of the cast support (1), the casting width of the cellulose ester solution, and the width of the film after winding are each larger than the above lower limit, and the liquid crystal display device has been enlarged in recent years. Correspondence.

Further, when the width of the cast belt (1), the casting width of the cellulose ester solution, and the width of the film after winding are each equal to or less than the upper limit, the amount of residual solvent of the film after peeling is large. , the film does not sag, or there is no growth unevenness.

Further, in the present embodiment, the peripheral speed of the cast-in-belt (1) is 80 to 200 m/min.

That is, by making the peripheral speed of the cast strip (1) faster than the conventional peripheral speed of the magnetic drum, the production speed of the film can be increased, and the productivity of the cellulose ester film can be increased.

In the temperature of the casting belt (1) at the time of film formation, in the general temperature range of 0 ° C ~ the solvent does not reach the boiling point temperature, in the mixed solvent, the lowest boiling point of the solvent can not be reached at the boiling point of the solvent, and then 5 The range of °C~solvent boiling point -5 °C is better.

The dopant cast by casting on the surface of the cast belt (1) as described above, the strength (film strength) of the gel film is increased by cooling gelation, and drying is promoted until it is peeled off. The strength (film strength) of the gel film is increased.

Further, in order to increase the film forming speed, two or more pressurized casting molds (12) may be provided on the casting belt (1) for casting, and the amount of the dopant may be divided into two layers to form a film.

On the cast belt (1), the web (10) is dried and solidified by the strip casting roll (16) due to the peeling film strength (16), so that the solvent remains in the web (10). It is preferable that the amount is dried to 150% by mass or less, and more preferably 80 to 120% by mass. Moreover, when the self-flow casting belt (1) peels the mesh (10) The mesh temperature is preferably 0 to 30 ° C. Further, the mesh (10) is evaporated by the solvent on the side of the self-flowing belt (1) on the surface of the self-casting belt (1), and the temperature is rapidly lowered, and volatilized by water vapor or solvent vapor in the atmosphere. The sexual component is easily condensed, so the temperature of the web at the time of peeling is preferably 5 to 30 ° C.

Here, the amount of residual solvent is represented by the following formula.

Residual solvent amount (% by mass) = {(M - N) / N} × 100

In the formula, M is the mass at any time point of the network, and N is the mass when the mass M is dried at 110 ° C for 3 hours.

Further, the elongation ratio is expressed by the following formula The stretching step of the stretching step (5) is the distance between the clips of the face: h, and the distance between the clips when the stretcher (5) of the stretching step is completed: when H is stretched Rate = H / h × 100%

A doped film (mesh) formed by a cast-cast dopant on the cast-cast strip (1) is heated on the cast-in-belt (1), and the self-casting strip (1) is passed through a peeling roll ( 3) The solvent is evaporated until the web is peelable.

In order to evaporate the solvent, there is a method of blowing the wind from the side of the web, and/or a method of transferring heat from the surface by radiant heat by means of heat transfer from the inner surface of the cast strip (1).

At the time of peeling, the film tends to grow in the conveying direction, and the film is easily narrowed in the wide-side direction, so that the self-flowing belt (1) causes the peeling tension of the web (10) at the time of peeling off the peeling roll (3), so that The peeling is preferably carried out at a minimum tension of -170 N/m, and further preferably at a minimum tension of -140 N/m.

After drying and solidifying the web (10) as a peelable film strength on the cast support (1), the web (10) is peeled off by a peeling roll (3), and then, in a stretching step The web (10) is stretched in the stretcher (5).

The amount of residual solvent of the web (film) (10) before entering the stretcher (5) of the stretching step is preferably 10 to 35 mass%.

In the stretching step, the warm air blowing means from the bottom of the stretcher (5) is close to the front portion, that is, the warm air (11) is blown in from the warm air spray slit (5a), and the self-tensioner is blown. (5) The discharge port (5b) near the rear portion of the chamber top discharges the exhaust air (12) to allow the mesh (10) to be dried while being stretched.

Further, in the stretching step of the present invention, the hot air blowing means, in particular, corresponds to the warm air ejection slit (5a) of the stretcher (5) of the stretching step, and is blown by the warm air. There is no particular limitation on the shape in which the film can be efficiently heated. For example, a slit shape as shown in the drawing or a punched plate shape can be exemplified.

In the present invention, the stretch ratio of the web in the stretcher (5) in the stretching step is 20 to 60%, and the warm air sprayed from the slit (5a) of the warm air is blown out in the stretcher (5) ( The temperature of 11) is Tg + 35 ° C ~ Tg + 80 ° C with respect to the glass transition temperature (Tg) of the film after winding. Further, the temperature is preferably from Tg + 40 ° C to Tg + 50 ° C.

Here, when the stretch ratio of the web (10) in the stretcher (5) in the stretching step does not reach the lower limit, it is not preferable because a film having a wide width cannot be obtained. Further, when the stretch ratio of the mesh (10) in the stretcher (5) exceeds the upper limit, the haze of the film rises, and the transmittance of the light is lowered. Therefore, in the case of incorporating the liquid crystal display device, the contrast is caused. It is not good to lower.

Further, in the stretcher (5) of the stretching step, the temperature of the warm air (11) ejected from the warm air jet slit opening (5a), if it is less than the lower limit value, is due to the film at the time of stretching When an unreasonable stress is applied, the haze is increased, and the transmittance of light is lowered, which is not preferable because the contrast is lowered when the liquid crystal display device is mounted. Further, when the temperature of the warm air (11) ejected from the warm air discharge slit (5a) in the stretcher (5) exceeds the upper limit value, the film is softened, and since it is not self-supporting, it is inside the stretcher. Or the mesh of the clip will be broken and it is not good.

Here, in the case where the temperature of the warm air (11) of the stretcher (5) in the stretching step is Tg + 35 ° C or more, a film having a wide width can be obtained, which is preferable. Further, when the temperature of the warm air (11) of the stretcher (5) in the stretching step is Tg + 80 ° C or less, the haze of the film does not rise, and the light transmittance is high, and in the case of being incorporated in a liquid crystal display device, It is better because it can prevent the reduction of the contrast.

In the drying step after the stripping of the self-casting strip (1), the web (or film) (10) shrinks in the broad direction due to evaporation of the solvent. The more dry the high temperature, the larger the shrinkage. This shrinkage is suppressed in a possible range while suppressing drying on one side, and it is appropriate that the planarity of the produced film is good.

The equal width or the transverse stretching of the stretching step is preferably carried out by the stretcher (5), either by a needle stretcher or by a clip stretcher.

In the present embodiment, the exhaust air (12) of the stretcher (5) from the stretching step contains a low molecular weight organic component (plasticizer or the like), and has two organic component removing devices (removal means). (13a) (13b), the organic component concentration in the exhaust air (14) after passing through the organic component removing devices (13a) (13b) is 1 to 100 μg/m ³ .

Further, in the present embodiment, the exhaust gas (14) of the organic component is removed by the organic component removing device (13a) (13b), and the stretcher (5) of the stretching step is again used as the warm wind of the upward flow. That is, it is reused as part of the dry wind (11). Further, the organic component removing device (13a) (13b) may be a plurality of persons as shown in the figure, and may be a plurality of segments, for example, two to four organic component removing devices (13a) (13b) are connected. It is better.

After the stretcher (5) of the stretching step, a post-drying device (6) is provided. In the post-drying device (6), the mesh (10) is meandered from the side by a plurality of conveying rollers (7) arranged in a thousand birds shape, and the mesh (10) is a dry object therebetween. Further, the film transport tension in the post-drying device (6) is affected by the physical properties of the dopant, the amount of residual solvent during the peeling and film transport steps, and the temperature of the post-drying device (6), and is 30~ 250N/m is preferred, and 60 to 150 N/m is preferred. The best at 80~120N/m.

Further, the means for drying the web (or film) (10) is not particularly limited, and is generally carried out by hot air, infrared rays, heating rolls, microwaves or the like. In terms of simplicity, it is preferred to dry the hot air, for example, from the bottom of the post-drying device (6), which is dried by the dry air (15) blown from the warm air inlet of the front portion, and the post-drying device (6) The outlet near the rear portion of the chamber top discharges the exhaust air (16) to be dried. The temperature of the dry wind (15) is preferably 40~160°C, and 50~160°C, because of the flatness and good dimensional stability. Good and better.

The steps from the above casting to the post-drying may be carried out in an air atmosphere or in an inert gas atmosphere such as a nitrogen gas. In this case, it is a matter of course to consider the concentration limit of the dry atmosphere solvent.

When the web is dried, the tension of the mesh is 30 to 300 N/m, preferably 40 to 270 N/m.

After the step from the casting to the post-drying, it is preferable to have a cleaning device for arranging the surface of the mesh (10).

In the cleaning device, the ultrasonic wave is applied to the mesh (10) in the middle of the transport, and the high-pressure air is blown onto the surface to scrape off and attract the deposit to remove the adhered dust or the like. In addition, a method of providing an adhesive roller, such as a method of performing a flame treatment (corona discharge treatment or plasma treatment), can be used without any particular limitation by a known means and method. In addition, the cleaning means of the configuration may be single or plural.

The adhesion to the dust of the mesh (10) or the like is caused by the action of static electricity. Therefore, before the cleaning device, a static elimination means, for example, a static elimination bar is disposed to remove the mesh (10). Static electricity is better. In addition to the electric rod, a well-known thing can be used without any limitation.

In the drying step, in order to evaporate the plasticizer contained in the web (10) to suppress the phenomenon of concentration in the roll or the wall surface, the supply air amount per unit time is set to a specific amount or more of fresh gas. Inflow is better. Next, the amount of fresh gas supplied is preferably set to 5 to 50% of the total supply air volume.

If the fresh gas supply is 5~50%, when it is less than 5%, it is fresh. If the amount of gas is too small, the concentration of the plasticizer cannot be sufficiently suppressed. When the amount of fresh gas exceeds 50%, the amount of fresh gas is excessive, so that the operating cost is extremely wasteful.

In order to prevent the growth direction of the film from being caused by the post-drying device (6), it is preferable to provide a tension cut roll. After the drying is completed, it is preferable to set a slitter before winding to cut the end portion because a good curling posture can be obtained.

With respect to the cellulose ester film of the drying step (6) after completion, the embossing process is formed on the film by the embossing processing means before the introduction of the winding step.

Here, the height h (μm) of the embossing is in the range of 0.05 to 0.3 times the film thickness T of the film, and the width W is set in the range of 0.005 to 0.02 times the film width L. Embossing can be formed on both sides of the film. In this case, the height h1+h2 (μm) of the embossing is set in the range of 0.05 to 0.3 times the film thickness T of the film, and the width W is set in the range of 0.005 to 0.02 times the film width L. For example, when the film thickness is 40 μm, the height h1+h2 (μm) of the embossing is set to 2 to 12 μm. The embossing width is set at 5~30mm.

Regarding the width of the embossing, it is necessary to reduce the thickness of the embossed portion, and for example, a film film of 50 μm or less is used for suppressing film sliding at a high speed of 50 m/min or more. The minimum is the necessary embossing width. However, even if the height of the aforementioned embossing is related, the pyramid shape, the horse-back shape, the polygonal shape, and the winding deviation fault are determined to determine the embossing height × the embossing width. Further, the embossing is not only the both end portions of the film but may be disposed at the central portion.

In the present invention, a static eliminator is provided before winding and after the winding portion to It is preferable to carry out the removal of the film.

The static eliminator is a method in which the charged potential of the original roll is further dispersed to ±2 Kv or less, and the neutralization device or the forced charging device is used to impart a reverse potential during winding, and may be a forced band. The electric current is located at 1 to 150 Hz for positive and negative alternating current converters to perform power removal.

Further, instead of the above-described neutralizer, a traveling ionizer or a static eliminating rod which causes ion wind generation can be utilized. The ionizer de-energizing system is continuously wound from the embossing processing device through the transfer roller and blows the ion wind toward the film. The ion wind system is caused by a neutralizer. In addition to electrical appliances, well-known things can be used without limitation.

The dried film (20) is wound by a winding device (8), and the amount of residual solvent of the dried film (20) is completed in the step of obtaining the original roll of the optical film, and is 0.5% by mass or less. It is preferably 0.1% by mass or less to obtain a film having good dimensional stability.

When the winding method of the film is used, the winding machine which is generally used may be used, and there are a method of controlling the tension such as a fixed-distance method, a constant-tension method, a tapered tension method, and a program tension control method in which internal stress is constant. These can be used flexibly.

For the bonding of the film of the winding core (core core), the tape may be bonded on both sides, or any one of the single-sided adhesive tapes may be used.

The cellulose ester film of the present invention preferably has a width of 1650 to 2500 mm after winding.

In the present invention, the film thickness after drying of the cellulose ester film is as a final processed film from the viewpoint of thinning of the liquid crystal display device. The range of 40 to 80 μm is preferred. Here, the film thickness after drying refers to a film in which the amount of residual solvent in the film is 0.5% by mass or less.

When the film thickness of the cellulose ester film after winding is too small, for example, the strength required as a protective film for a polarizing plate may not be obtained. When the film thickness of the film is too thick, the film is superior to the conventional cellulose ester film. In the adjustment of the film thickness, in order to achieve the desired thickness, to control the dopant concentration, the pump liquid supply amount, the slit gap of the metal cover of the flow mold, the extrusion pressure of the flow mold, and the speed of the cast support Wait. Further, in terms of means for uniformizing the film thickness, it is preferable to use a film thickness detecting means to feed back the stylized feedback information to the respective devices.

In the step of drying after the self-flow molding by the solution casting method, the atmosphere in the drying apparatus may be made into air, or may be carried out in an inert gas atmosphere such as a nitrogen gas or a carbon dioxide gas. However, the danger of evaporating the outbreak boundary of the solvent in a dry atmosphere must often be taken into consideration.

In the present invention, the cellulose ester film preferably has a water content of 0.1 to 5%, preferably 0.3 to 4%, more preferably 0.5 to 2%.

In the present invention, the cellulose ester film has a transmittance of 90% or more, more preferably 92% or more, and still more preferably 93% or more.

Further, the cellulose ester film produced by the method of the present invention has a haze of 0.3 to 2.0 in the case of overlapping three sheets, and the cellulose ester film according to the present invention has a haze of very low film, so that it is transparent. Sexual and planar optical properties.

In the present embodiment, the in-plane direction defined by the following formula is delayed (R0), and is 30 to 300 nm at a temperature of 23 ° C and a humidity of 55% RH. The retardation (Rt) is 70 to 400 nm at a temperature of 23 ° C and a humidity of 55% RH.

R0=(nx-ny)×d Rt={(nx+ny)/2-nz}×d (wherein R0 represents the in-plane retardation value of the film, Rt represents the film thickness direction retardation value, nx represents the refractive index of the film in the in-plane axis direction, ny represents the refractive index of the in-plane axis direction of the film, and nz shows the film thickness. The refractive index of the direction (the refractive index is measured at a wavelength of 590 nm), and d is the thickness (nm) of the film.

Further, the retardation values R0, Rt are measured using an automatic complex refractometer. For example, KOBRA-21ADH (manufactured by Oji Scientific Instruments Co., Ltd.) can be used, and the wavelength is obtained at 590 nm in an environment of a temperature of 23 ° C and a humidity of 55% RH.

The cellulose ester film produced by the method of the present invention, the member for liquid crystal display, and more preferably used as a protective film for a polarizing plate. In particular, the cellulose ester film produced by the method of the present invention can be suitably used in a protective film for a polarizing plate which has a strict requirement for moisture permeability and dimensional stability.

By using the protective film for a polarizing plate formed by the cellulose ester film of the present embodiment, it is possible to provide a polarizing plate excellent in durability and dimensional stability and excellent in optical isotropy, while being thinned.

However, the polarizing film is a conventionally used film which is stretch-aligned like a polyvinyl alcohol film, and is longitudinally stretched by treatment with an iodine dichroic dye. For the polarizing film itself, due to insufficient strength and durability, Therefore, in general, a cellulose ester film which is a directionality of a protective film can be bonded to both sides as a polarizing plate.

The above-mentioned polarizing plate is produced by laminating a cellulose ester film produced by the method of the present invention as a retardation film, and the cellulose ester film produced by the method of the present invention is also used as a retardation film and a protective film, and directly Polarized film bonding can also be produced. The bonding method is not particularly limited, and it can be carried out by using an aqueous solution of a water-soluble polymer as an adhesive.

The water-soluble polymer binder is preferably a fully saponified polyvinyl alcohol aqueous solution. Further, in the longitudinal direction, the elongated polarizing film treated with the dichroic dye and the retardation film produced by the elongated method of the present invention are bonded together to obtain an elongated polarizing plate. The polarizing plate is a laminated type which is a laminated release sheet by a pressure-sensitive adhesive layer (for example, an acrylic pressure-sensitive adhesive layer or the like) on one or both sides thereof (by peeling off the release sheet) It can be easily attached to a liquid crystal cell, etc.).

The polarizing plate thus obtained can be used for various display devices. In particular, when the voltage is not applied, the liquid crystal molecules are substantially vertically aligned in the vA mode, or when the voltage is not applied, the liquid crystal molecules are substantially liquid crystal display devices using a liquid crystal cell in a horizontally and twist-aligned TN mode. .

However, the polarizing plate can be produced by a general method. For example, an optical film or a cellulose ester film is subjected to an alkali saponification treatment, and a polyvinyl alcohol film is immersed in an iodine solution, and both sides of the polarizing film produced by stretching are applied, and a method of laminating a completely saponified polyvinyl alcohol aqueous solution is used. The alkali saponification treatment means that the water-based adhesive has good wettability, and in order to improve the adhesion, the fiber is made. The ester film is impregnated in a high temperature alkaline lye.

The cellulose ester film produced by the method of the present embodiment can be provided with a hard coat layer, an antiglare layer, an antireflection layer, an antifouling layer, an antistatic layer, a conductive layer, an optical anisotropic layer, a liquid crystal layer, and an alignment. Layer, adhesive layer, adhesive layer, BASECOAT LAYER and other functional layers. The functional layers can be applied by coating or evaporation, sputtering, plasma CVD, atmospheric piezoelectric slurry treatment, and the like.

The polarizing plate obtained in this manner is provided on one side or both sides of the liquid crystal cell, and a liquid crystal display device can be obtained by using the same.

In the present invention, the liquid crystal display device has a liquid crystal cell in which rod-shaped liquid crystal molecules are held by a pair of glass substrates, a polarizing film disposed by sandwiching a liquid crystal cell, and a transparent protective layer disposed on both sides thereof. Made into 2 polarizers.

By using the protective film for a polarizing plate formed by the cellulose ester film produced by the method of the present invention, it is possible to provide a polarizing plate which is thinned, excellent in durability and dimensional stability, and excellent in optical isotropic properties. Further, the liquid crystal display device using the polarizing plate or the retardation film can maintain stable display performance over a long period of time.

The cellulose ester film produced by the method of the present embodiment can be used as a substrate for an antireflection film or an optical compensation film.

[Examples]

Hereinafter, the present invention will be specifically described by way of examples, but the present invention Not limited to these.

Example 1

(dopant composition 1

The above materials were placed in a sealed container in this order, and the temperature in the container was raised from 20 ° C to 80 ° C, and then the temperature was maintained at 80 ° C for 3 hours while stirring to completely dissolve the cellulose triacetate. Thereafter, the stirring was stopped to lower the liquid temperature to 43 °C. This dopant was filtered using a filter paper (manufactured by Assembly Paper Co., Ltd., Augmentation Filter No. 244) to obtain a dopant.

Using the cast-molded support solution casting and film forming apparatus shown in Fig. 1, on the support (1) of the endless belt of the rotating stainless steel having the mirror-finished surface, the prepared dopant is carried out as described above. First-class casting, the dopant film (mesh) formed by casting is dried on the support (1), so that the mesh reaches the underside of the support formed by the endless belt, at approximately one turn, The web (film) (10) is peeled off from the support (1) by a peeling roll (3).

Next, the peeled mesh (10) is introduced into the stretcher (5), and the ends of the mesh are clamped by clips, and the temperature of 160 ° C is blown under the width of the sample ( 11) Drying while stretching the web (10) toward the broad side.

Here, the residual solvent amount of the mesh (film) (10) before entering the stretcher (5) of the stretching step was 12% by mass.

Next, in the stretcher (5) of the stretching step, the stretch ratio of the web is 20%, and in the stretcher (5), the warm air is sprayed from the slit (5a). The temperature becomes 160 °C. Here, the temperature of the warm air (11) of the stretcher (5) is Tg + 35 ° C with respect to the glass transition temperature of the cellulose triacetate film after winding: Tg = 125 °C.

Further, in this embodiment, the two-string organic component removing device (13a) (13b) for removing the organic component other than the solvent contained in the exhaust air (12) of the stretcher (5) is passed through The concentration of the low molecular weight organic component in the exhaust air (14) after the organic component removing device (13a) (13b) was 20 μg/m ³ .

Further, the measurement of the organic component contained in the exhaust air (12) of the stretcher (5) is performed by GC/MS in a sealed state by using a certain volume of exhaust air as a sample.

In this way, the exhaust air (14), which removes the organic component by the organic component removing device (13a) (13b), can be again used as part of the upstream warm air (11) by the stretcher (5). Reuse.

Thereafter, the mesh (film) (10) is placed in a thousand bird shape from the side view, and is carried out by a roll transport drying device (6) having a plurality of mirror conveyance rollers (7), and dried at 100 ° C (15). dry. Drying the finished film (20) by The winding device (8) was wound to finally obtain a cellulose triacetate film (20) having a film thickness of 80 μm and a film width of 1,860 mm.

Further, embossing is performed on both end portions in the width direction of the cellulose acetate film wound around the winding roller, so that the height of the convex portion due to embossing is in the range of 4 to 12 μm, and embossing is performed at the same time. The height difference of the convex portions is 2 μm or less.

A method of removing or reducing the surface potential of the cellulose acetate film at the time of winding is a DE-ELECTRIFYING BLOWER.

Table 1 below shows the types of dopant compositions used in the production of cellulose triacetate film, the elongation (%) of the web (10), and the stretcher (5) in the stretching step. The temperature of the warm air (11) sprayed by the warm air jet (5a) (°C), the glass transition temperature (Tg) of the cellulose triacetate film after winding (°C), before entering the stretcher (5) The amount of residual solvent (%) entering the network (10), and the film thickness (μm).

Next, the haze value of the cellulose triacetate film obtained in this Example 1 was measured, and the results are summarized in Table 1 below.

Here, the haze of the cellulose triacetate film can be measured in the next manner. That is, the film of the cast film is sampled, and 10 of them are arbitrarily selected, and a haze meter (1001DP type, manufactured by Nippon Denshoku Industries Co., Ltd.) is used in accordance with the method specified in JIS K6714. Three sheets of the acid ester film were used to measure the haze.

Example 2~15

In the same manner as in the above-described Embodiment 1, the dopant composition 1 is used. A cellulose triacetate film is produced, and in each of the examples, a part of the film forming conditions, such as the following, is various.

First, in Example 2, the conditions were substantially the same as in the case of Example 1, and the stretch ratio of the web (10) of the stretcher (5) in the stretching step was changed to 30 (%).

In the third and fourth embodiments, the conditions are substantially the same as those in the first and second embodiments, and the temperature of the warm air (11) ejected from the warm air blowing slit (5a) in the stretcher (5) is changed to 170 °C. .

In the same manner as in the fifth and sixth embodiments, the conditions were substantially the same as those in the first and second embodiments, and the temperature of the warm air (11) was changed to 180 °C.

In Example 7, the conditions were substantially the same as in the case of Example 5, but the elongation of the web (10) was changed to 40 (%).

Example 8 was substantially the same as in the case of Example 7, except that the elongation of the web (10) was changed to 55 (%) while the web (10) before entering the stretcher (5). The change in the amount of residual solvent entered was 35 (%).

In the case of Example 9, the conditions were substantially the same as those in Example 7, and the temperature of the warm air (11) was changed to 200 °C.

In Example 10, the conditions were substantially the same as in the case of Example 9, and the amount of the residual solvent entering the web (10) before entering the stretcher (5) was changed to 35 (%).

In the eleventh embodiment, the conditions were substantially the same as those in the case of Example 10, and the elongation of the web (10) was changed to 60 (%).

In the case of the embodiments 12 and 13 and the case of the embodiment 6, the residual solvent amount of the mesh (10) before entering the stretcher (5) was changed to 20% by mass, 35% by mass.

In Examples 14 and 15, the film thicknesses of the films were changed to 40 μm and 60 μm, respectively, under substantially the same conditions as in the case of Example 6.

Comparative Examples 1~6

For the sake of comparison, the cellulose triacetate film was produced using the dopant composition 1 of the above Example 1, but differs from the case of the above-described Example 1 in Comparative Examples 1 and 6, The stretch ratio (%) of the web (10) of the stretcher (5) was 18% and 65% outside the range of the present invention. In Comparative Examples 2 to 5, the temperature of the warm air (11) ejected from the warm air discharge slit (5a) in the stretcher (5) was outside the range of the present invention.

Further, in Comparative Example 6, the dopant composition 1 of the above-described Example 1 was used, and in order to produce a cellulose triacetate film having a thickness of 80 μm, the film was stretched as in the case of the above-described Example 1. In the apparatus (5), when the web (10) is stretched at a stretch ratio of 65%, the web (10) is broken, and the film cannot be formed.

As shown in the following Table 1, in the examples 2 to 15, and in the comparative examples 1 to 6, the type of the dopant composition for the production of the cellulose triacetate film, the elongation ratio of the mesh (10) (%) ), the temperature of the warm air (11) ejected from the warm air blowing slit (5a) of the stretcher (5), and the glass transition temperature (Tg) of the cellulose triacetate film (°C) The amount of residual solvent (%) entering the web (10) before entering the stretcher (5), and the film thickness (μm) are summarized.

Next, with respect to the cellulose triacetate films obtained in Examples 2 to 15 and Comparative Examples 1 to 5, the haze value of the film was the same as in the case of Example 1 described above. The results were measured and the results obtained are summarized in Table 1 below.

Example 16

The cellulose acetate propionate film was produced in substantially the same manner as in the above-described Example 1 by using the dopant composition 2 described below.

(Doping composition 2)

In this embodiment 16, the residual solvent amount of the web (10) before entering the stretcher (5) of the stretching step is 12% by mass, and the web (10) is in the stretcher (5). The elongation rate was 25%. Further, the temperature of the warm air (11) ejected from the warm air blowing slit (5a) in the stretcher (5) was 185 °C.

Here, at the temperature of the warm air (11) of the stretcher (5), the glass transition temperature of the cellulose acetate propionate film after winding: Tg = 145 ° C is Tg + 40 ° C. The film thickness of the cellulose acetate propionate film after winding becomes 40μm.

Examples 17~26

In the same manner as in the above-described Example 16, the cellulose acetate propionate was produced using the dopant composition 2, but in each of the examples, one of the film forming conditions, such as the second method, was various. Different things.

First, in Examples 17 and 18, in the same manner as in the case of Example 16, the stretch ratio of the web (10) of the stretcher (5) in the stretching step was changed to 35 (%), 40 ( %).

In the embodiment 19, the stretching ratio of the web (10) of the stretcher (5) of the stretching step was changed to 60 (%) under substantially the same conditions as in the case of the embodiment 16, and at the same time, in the stretcher (5) The temperature of the warm air (11) ejected from the gap opening (5a) from the warm air is changed to 180 °C.

In the embodiment 20, the temperature of the warm air (11) ejected from the warm air discharge slit (5a) in the stretcher (5) was changed to 200 ° C under substantially the same conditions as in the case of the embodiment 18.

In Examples 21 to 23, substantially the same conditions as in the case of Example 17, the amount of the residual solvent entering the web (10) before entering the stretcher (5) was changed to 10 (%), 20 (%). ), 35 (%).

In Examples 24 to 26, the film thicknesses of the films were changed to 50 μm, 60 μm, and 80 μm, respectively, under substantially the same conditions as in the case of Example 17.

Comparative Example 7~9

For the sake of comparison, the dopant composition 2 of the above embodiment 16 is used. To produce a cellulose acetate propionate film, but in the case of the difference from the above-described embodiment 16, the warm air ejected from the slit (5a) from the warm air in the stretcher (5) ( The temperature of 11) is outside the scope of the present invention.

The elongation ratio of the mesh (10) in the production of the cellulose acetate propionate film in Examples 16 to 26 and Comparative Examples 7 to 9 as shown in Table 1 below. (%), the temperature of the warm air (11) sprayed by the warm air spray slit (5a) of the stretcher (5) (°C), and the glass transition temperature (Tg) of the cellulose acetate propionate film after winding (°C), the amount of residual solvent (%) entering the film of the stretcher (5), and the film thickness (μm) are summarized.

Next, the cellulose acetate propionate films obtained in Examples 16 to 26 and Comparative Examples 7 to 9 were measured in the same manner as in the case of Example 1 above, and the results were summarized in the results. Table 1 below.

Comparative Example 10

For the sake of comparison, a cellulose acetate propionate film was produced in substantially the same manner as in the above-described Example 1 by using the following dopant composition 3.

(Doping composition 3)

Here, the amount of residual solvent of the web (film) (10) before entering the stretcher (5) of the stretching step was 12% by mass.

Next, the stretch ratio of the web is 30% in the stretcher (5), and the temperature of the warm air (11) ejected from the warm air discharge slit (5a) in the stretcher (5) becomes 180 ° C. Here, the temperature of the warm air (11) of the stretcher (5) is Tg + 70 ° C with respect to the glass transition temperature of the cellulose triacetate film after winding: Tg = 110 ° C.

In the dopant composition 3 of Comparative Example 10, since the plasticizer is not contained, in the stretcher (5), when the web (10) is stretched at a stretching ratio of 10% or more, It caused a break and it was impossible to make a film.

It can be seen from the results of the above Table 1 that in the cellulose ester film of Examples 1 to 26 of the present invention, in the method for producing a cellulose ester film by a solution casting method, even if the so-called high stretching, the haze of the film cannot be When it is high, it is possible to produce optical properties excellent in transparency and flatness, and a cellulose ester film. At the same time, the production speed can be improved, the productivity of the film can be improved, and the film for a protective film for a polarizing plate can be obtained in recent years. Requirements for widening, widening, and high quality.

On the other hand, in the cellulose ester film obtained in Comparative Examples 1 to 5 and Comparative Examples 7 to 9, when the film was stretched at a high degree, the haze of the film became high, and the transparency and flatness were lowered. Therefore, the production speed of the cellulose ester film cannot be improved, and the productivity of the film cannot be improved, and the film thickness of the protective film for a polarizing plate, the width, and the high quality cannot be met.

Example 27

(production of polarizing film)

In order to produce the liquid crystal display panel shown in Fig. 2, first, a polarizing film is produced. That is, a polyvinyl alcohol film having a thickness of 120 μm was subjected to one-axis stretching at a temperature of 110 ° C and a draw ratio of 5 times. The mixture was immersed in an aqueous solution of 0.075 g of iodine, 5 g of potassium iodide and 100 g of water for 60 seconds, and then immersed in 6 g of potassium iodide, 7.5 g of boric acid, and 100 g of water to obtain an aqueous solution of 68 ° C. This was washed with water and dried to obtain a polarizing film 103.

(production of polarizing plate)

Next, in accordance with the following steps 1 to 5, in the above polarizing film 103, A cellulose triacetate film 104 (T-1) having a film thickness of 80 μm produced in Example 6 and a cellulose acetate propionate film 105 (T-2) having a film thickness of 40 μm produced in Example 21 The polarizing plate 1 (P1) is produced by laminating. The mixture was immersed in a 2 mol/L sodium hydroxide solution at 50 ° C for 60 seconds, followed by washing with water, and drying to obtain a film of the saponified T-1, T-2 which was bonded to the polarizing film.

Step 2: The polarizing film was immersed in a polyvinyl alcohol adhesive tank having a solid content of 2% by mass for 1 to 2 seconds.

Step 3: The excess adhesive attached to the polarizing film in step 2 is gently wiped off, and the T-1 and T-2 films treated in the step 1 are laminated on both sides of the polarizing film.

Step 4: The polarizing film disposed in the step 3 and the film of T-1 and T-2 are bonded at a pressure of 20 to 30 N/cm ² and a conveying speed of about 2 m/min.

Step 5: The polarizing film prepared in the step 4 and the film of T-1 and T-2 were dried in a dryer at 80 ° C for 2 minutes to prepare a polarizing plate 1 (P1).

Then, in the case of the polarizing plate 2 (P2) bonded to the other surface of the liquid crystal display panel, the polarizing plate 1 (P1) produced in the same manner as described above is used, and the bonding direction is centered on the liquid crystal. Symmetrical configuration.

Therefore, as shown in Table 2, the film T-3 (106) of the polarizing plate 2 (P2) was a cellulose acetate propionate film having a film thickness of 40 μm produced in Example 21, and the polarizing plate 2 (P2). The film T-4 (107) was a cellulose triacetate film having a film thickness of 80 μm produced in Example 6.

(Production of liquid crystal display panel)

Next, a commercially available liquid crystal display panel (NEC color liquid crystal display) , MultiSync, LCD1525J: Model Name, LA-1529HM) The polarizing plates on both sides are carefully peeled off, and the liquid crystal 108 is bonded to the polarizing plate 1 (P1) and the polarizing plate 2 (P2) produced as described above. The liquid crystal display panel 100.

At this time, as shown in FIG. 2, a cellulose triacetate film 104 having a film thickness of 80 μm produced in Example 6 of the polarizing plate 1 (P1) and the polarizing plate 2 (P2) was used as the center liquid crystal 108 ( T-1) and 107 (T-4) were each on the outer side, and each of the cellulose acetate propionate films 105 (T-2) and 106 (T-3) having a film thickness of 40 μm produced in Example 21 was used. It fits in the way of becoming the center of the liquid crystal 108 side.

Next, in this case, the side of the outer film 104 (T-1) of the polarizing plate 1 (P1) is the display side 101 of the liquid crystal display panel, and the film 107 (T-4) of the outer side of the polarizing plate 2 (P2) is the backlight side 102. .

The liquid crystal display panel of Example 27 thus obtained was measured and compared, and the results obtained are shown in Table 2 below.

(measurement of comparison when the panel is assembled)

The measurement of the comparison when the display panel is assembled is carried out by evaluating the viewing angle of the display panel. Here, in the viewing angle evaluation, the viewing angle was measured using the EZ-contrast manufactured by ELDIM Co., Ltd. on the liquid crystal display panel. The measurement method is based on the white display of the liquid crystal display panel, and compared with the black display, the comparison is performed within the range of the following values in all directions from the comparison of the inclination angle of 80° with respect to the normal direction of the panel surface.

◎◎◎: The comparison is more than 40 in all directions

◎ ◎: Comparison is more than 30 in all directions

◎: Comparison is more than 20 in all directions

○: The comparison is more than 15 in all directions.

△: There is a region where the comparison is more than 5 in all directions, and the area is less than 15

×: There is a contrast area that is not up to the full range of 5

Examples 28~31

A liquid crystal display panel was produced in the same manner as in the case of the embodiment 27, but the point different from the case of the above-described embodiment 27 is as follows.

In Example 28, a cellulose triacetate film (T-1) having a film thickness of 80 μm produced in Example 6 and a cellulose acetate having a film thickness of 60 μm produced in Example 25 were used as the polarizing film. In the case where the polarizing plate 1 is bonded to the other side of the liquid crystal display panel, the polarizing plate 1 is bonded to the other side of the liquid crystal display panel, and the polarizing plate 1 is used in the same manner as described above. The bonding direction is centered on the liquid crystal and becomes a symmetric mode.

Therefore, as shown in Table 3, the film T-3 of the polarizing plate 2 was a cellulose acetate propionate film having a film thickness of 60 μm produced in Example 25, and the film T-4 of the polarizing plate 2 was obtained as Example 6. A cellulose triacetate film having a film thickness of 80 μm was produced.

In Example 29, a cellulose triacetate film (T-1) having a film thickness of 80 μm produced in Example 6 and a cellulose acetate propionate having a film thickness of 80 μm prepared in Example 26 were used in the polarizing film. In the case where the polarizing plate 1 is bonded to the other side of the liquid crystal display panel, the polarizing plate 1 is bonded to the other side of the liquid crystal display panel, and the polarizing plate 1 is used in the same manner as described above. The combined direction is centered on the liquid crystal and is arranged symmetrically.

Therefore, as shown in Table 2, the film T-3 of the polarizing plate 2 was a cellulose acetate propionate film having a film thickness of 80 μm produced in Example 26, and polarized light. The film T-4 of the plate 2 was a cellulose triacetate film having a film thickness of 80 μm produced in Example 6.

In Example 30, a cellulose triacetate film (T-1) having a film thickness of 80 μm produced in Example 13 and a cellulose acetate having a film thickness of 60 μm produced in Example 25 were used as the polarizing film. The polarizing plate 1 is bonded to the polarizing plate 1 which is bonded to the other surface of the liquid crystal display panel, and the polarizing plate 1 produced in the same manner as described above is bonded thereto. The direction is arranged symmetrically around the liquid crystal.

Therefore, as shown in Table 2, the film T-3 of the polarizing plate 2 is a cellulose acetate propionate film having a film thickness of 60 μm produced in Example 25, and the film T-4 of the polarizing plate 2 is an example. A cellulose triacetate film having a film thickness of 80 μm produced in 13 cases.

In Example 31, a cellulose triacetate film (T-1) having a film thickness of 80 μm produced in Example 13 and a cellulose acetate having a film thickness of 40 μm produced in Example 17 were used in the polarizing film. The polarizing plate 1 is produced by bonding the propionate film (T-2) to the polarizing plate 1 and bonding the polarizing plate 2 to the other side of the liquid crystal display panel. The bonding direction is arranged symmetrically around the liquid crystal.

Therefore, as shown in Table 2, the film T-3 of the polarizing plate 2 was a cellulose acetate propionate film having a film thickness of 40 μm produced in Example 17, and the film T-4 of the polarizing plate 2 was implemented. A cellulose triacetate film having a film thickness of 80 μm produced in Example 13.

The liquid crystal display panels of Examples 28 to 31 thus obtained were measured and compared in the same manner as in Example 27, and the results obtained are shown in the following table. 2 indicates.

Comparative Example 11

In the comparative example, a liquid crystal display panel was produced in the same manner as in the case of the above-mentioned Example 27. However, in the case of the above-described Example 27, the cellulose film of the film thickness of 80 μm produced in Comparative Example 2 was used in the polarizing film. The acid ester film (T-1) was bonded to the cellulose acetate propionate film (T-2) having a film thickness of 80 μm produced in Comparative Example 8 to form a polarizing plate 1, and the liquid crystal display panel was additionally provided. In the case of the polarizing plate 2 to be bonded to one side, the polarizing plate 1 produced in the same manner as described above is used, and the bonding direction is arranged symmetrically around the liquid crystal.

Therefore, as shown in Table 2, the film T-3 of the polarizing plate 2 is a cellulose acetate propionate film having a film thickness of 80 μm produced in Comparative Example 8, and the film T-4 of the polarizing plate 2 is a comparative example. 2 A cellulose triacetate film having a film thickness of 80 μm.

The liquid crystal display panel of Comparative Example 11 thus obtained was measured and compared in the same manner as in Example 27, and the results obtained are shown in Table 2 below.

As is apparent from the results of the above Table 2, the liquid crystal display panels according to Examples 27 to 31 of the present invention have an excellent contrast as compared with the liquid crystal display panel of Comparative Example 11.

1‧‧‧Ring belt (cast casting support)

2‧‧‧Flow mold

3‧‧‧ peeling roller

5‧‧‧Drawer (stretching step)

5a‧‧‧Warm air vents the gap (warm air blasting means)

5b‧‧‧Exhaust air outlet

6‧‧‧Rolling conveyor drying device

7‧‧‧Transport roller

8‧‧‧Winding machine

10‧‧‧ mesh (web)

11‧‧‧Warm wind (dry wind)

12‧‧‧Exhaust wind

13a‧‧‧ Organic component removal device (organic component removal means)

13b‧‧‧ Organic component removal device (organic component removal means)

14‧‧‧Exhaust wind

15‧‧‧dry wind

16‧‧‧Exhaust wind

20‧‧‧Cellulose ester film

100‧‧‧LCD panel

101‧‧‧ display side

102‧‧‧Back side

P1‧‧‧ polarizing plate 1

P2‧‧‧ polarizing plate 2

103‧‧‧ polarizing film

104‧‧‧T-1 film

105‧‧‧T-2 film

106‧‧‧T-3 film

107‧‧‧T-4 film

108‧‧‧LCD

Fig. 1 is a flow chart showing a specific example of an apparatus for producing a cellulose ester film of the present invention.

Fig. 2 is an enlarged cross-sectional view showing a specific example of a liquid crystal display panel using a cellulose ester film produced by the method of the present invention.

1‧‧‧Ring belt (cast casting support)

2‧‧‧Flow mold

3‧‧‧ peeling roller

5‧‧‧Drawer (stretching step)

5a‧‧‧Warm air vents the gap (warm air blasting means)

5b‧‧‧Exhaust air outlet

6‧‧‧Rolling conveyor drying device

7‧‧‧Transport roller

8‧‧‧Winding machine

10‧‧‧ mesh (web)

11‧‧‧Warm wind (dry wind)

12‧‧‧Exhaust wind

13a‧‧‧ Organic component removal device (organic component removal means)

13b‧‧‧ Organic component removal device (organic component removal means)

14‧‧‧Exhaust wind

15‧‧‧dry wind

16‧‧‧Exhaust wind

20‧‧‧Cellulose ester film

Claims (9)

A method for producing a cellulose ester film, wherein a resin solution containing a cellulose ester resin is casted in a cast support to form a cast film, and the solvent in the cast film is dried until the cast film becomes peelable After the stripping support is peeled off, the stretching step of stretching the both ends of the peeled web in the widthwise direction is performed, and the solvent is dried, and the cellulose ester film of the cellulose ester film is obtained by winding. The manufacturing method is characterized in that the stretching ratio of the mesh in the stretching step is 20 to 60%, and the temperature of the warming air spouted from the warm air spraying means in the stretching step is relative to the film after winding The glass transition temperature (Tg) is Tg + 35 ° C ~ Tg + 80 ° C. The method for producing a cellulose ester film according to the first aspect of the invention, wherein the residual solvent amount of the film before entering the stretching step is 10 to 35% by mass. The method for producing a cellulose ester film according to the first or second aspect of the invention, which has a means for removing an organic component other than the solvent contained in the exhaust air sent from the stretching step. A method for producing a cellulose ester film according to claim 3, wherein the exhaust air from which the organic component is removed is reused as part of the dry air upstream of the stretching step. The method for producing a cellulose ester film according to claim 4, wherein the removing means is a plurality of connectors. A cellulose ester film produced by the method according to any one of claims 1 to 3, which is characterized in that the film width after winding is from 1650 to 2500 mm. The cellulose ester film of claim 6, wherein the film thickness after winding is 40 to 80 μm. A polarizing plate characterized by using a cellulose ester film according to item 6 or item 7 of the patent application for one side. A display device characterized by using a cellulose ester film as claimed in claim 6 or 7.