KR20090117718A - Cellulose ester film, method for production of the cellulose ester film, and polarizing plate and display device both using the cellulose ester film - Google Patents

Abstract

Disclosed are: a method for producing a cellulose ester film which, when a web of the cellulose ester film is stretched in the widthwise direction by 1.2 times or more in a web stretching step, is not increased in its haze; a cellulose ester film produced by the method; and a polarizing plate and a display device both using the film. Specifically disclosed is a method for producing a cellulose ester film by a solution casting film formation technique. In the method, the draw ratio of a web of the cellulose ester film in a stretching step is 20 to 60%, and the temperature of a hot air brown from a hot air blow-off means in the stretching step is higher than the glass transition temperature (Tg) of the taken-up film by 35 to 80°C. Preferably, the amount of a solvent remaining in the film immediately before the stretching step is 10 to 35 mass%.

Description

Cellulose ester film, its manufacturing method, polarizing plate using cellulose ester film, and display apparatus {CELLULOSE ESTER FILM, METHOD FOR PRODUCTION OF THE CELLULOSE ESTER FILM, AND POLARIZING PLATE AND DISPLAY DEVICE BOTH USING THE CELLULOSE ESTER FILM}

This invention is a cellulose ester film which can be used also for various functional films, such as a protective film for polarizing plates used for a liquid crystal display device (LCD), a retardation film, a viewing angle expansion film, an antireflection film used for a plasma display, and its manufacturing method. , A polarizing plate using a cellulose ester film, and a display device.

Background Art In recent years, liquid crystal display devices have been used for televisions and large-scale monitors due to the improvement in image quality and the enhancement of high-definition technology, and in particular, there is a demand for large-sized liquid crystal display devices and cost reduction by efficient production. The material of a liquid crystal display device is also strengthened, and widening of an optical film is calculated | required.

Moreover, in recent years, in order to cope with the rapid expansion of a liquid crystal TV, the demand of an optical film is also rapidly expanding, and productivity improvement is strongly requested | required. About the cellulose-ester film formed into a film by the solution casting | flow_spreading method, since the amount of solvent to dry is at least a thin film, a production speed increase is possible.

It is possible to obtain a wide film by the solution casting film formation method by expanding the casting width on the casting support which consists of an endless belt of rotation drive stainless steel, a drum of stainless steel, etc.

On the other hand, the width of the flexible support and the flexible die has an upper limit due to restrictions in manufacturing the device. When the flexible support is an endless belt, the upper limit of the width is now 2000 mm. The upper limit of the flexible width in that case is about 1900 mm at maximum, considering the meandering etc. at the time of an endless belt conveyance. Moreover, even when a flexible support body is a metal drum, the maximum width is about 2500 mm from the same manufacturing restrictions. In the case of drum film forming, the flexible film is self-supporting due to gelation by cooling, and thus film forming in the cooled part is required, but the end part has a temperature change due to heat dissipation and cannot be used. Stops at

Since the width | variety at the time of casting | flow_spread is limited by the limitation on equipment manufacture, in all, it is conceivable to obtain the film | membrane of a wide width by extending | stretching the film after casting, and taking the film width as wide as possible. As a method of extending | stretching the film after casting | flow_spread, and obtaining a wide film | membrane, it is known with PET, polyvinyl alcohol, etc., It is extending | stretching about 2 to 4 times with respect to casting | flow_spread width | variety, and obtained the wide film | membrane.

By the way, in the case of a cellulose ester film, it has been thought until now that elongation cannot be made high because of rigidity of molecular structure. In following patent document 1 and patent document 2, extending | stretching a cellulose ester film by 1.2 times is proposed.

Patent Document 1 discloses stretching at 1.2 to 4.0 times when the amount of residual solvent is less than 120% by mass and the temperature is 115 ° C or more and 160 ° C or less. Moreover, patent document 2 describes extending | stretching 1.2 times or more and 1.8 times or less when the temperature is room temperature to 160 degrees C or less in the thermostat of which the temperature difference of a film passage part is 0 degreeC or more and 4 degrees C or less.

Patent Document 1: Japanese Patent Application Laid-Open No. 2002-71957

Patent Document 2: Japanese Patent Application Laid-Open No. 2002-131540

However, in the manufacturing methods described in Patent Documents 1 and 2, the haze of the cellulose esters is increased and the light transmittance is lowered, so that there is a problem that the contrast is lowered when assembled to the display device. And this problem is considered to be because an excessive force is applied to the film at the time of stretching.

An object of the present invention is to solve the above-described problems of the prior art, and in the stretching step of the web, a method of producing a cellulose ester film in which the haze does not increase even when the web is stretched 1.2 times or more in the width direction, by the method It is providing the polarizing plate using the manufactured cellulose ester film, the cellulose ester film, and a display apparatus.

Means for solving the problem

In order to achieve the above object, the invention according to claim 1, wherein the resin solution containing the cellulose ester resin is cast on the flexible support to form a cast film, and the solvent in the cast film is dried until the cast film can be peeled off. And a peeling step from the flexible support, followed by an extending step of gripping both ends of the peeled web and stretching in the width direction, followed by drying and winding up the solvent to obtain a cellulose ester film to obtain a cellulose ester film. Elongation rate of the web in 20-60%, and the temperature of the warm air which blows off from the warm air blowing means in an extending process is Tg + 35 degreeC-Tg + 80 with respect to the glass transition temperature (Tg) of the film after winding up. It is characterized by the above-mentioned.

Invention of Claim 2 is a manufacturing method of the cellulose-ester film of Claim 1, and is 10-35 mass% of residual solvent amount of the film just before entering into an extending process.

Invention of Claim 3 is a manufacturing method of the cellulose-ester film of Claim 1, Comprising: It has a removal means which removes organic components other than the solvent contained in the exhaust wind sent from the extending process. It features.

Invention of Claim 4 is a manufacturing method of the cellulose-ester film of Claim 3, The exhaust wind which removed the said organic component is reused again as a part of dry wind upstream rather than an extending process.

Invention of Claim 5 is a manufacturing method of the cellulose-ester film of Claim 4, Comprising: The said removal means is connected in multiple numbers, It is characterized by the above-mentioned.

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

Invention of Claim 7 is the cellulose-ester film of Claim 6, and the film thickness of the film after winding is 40-80 micrometers, It is characterized by the above-mentioned.

The invention of the polarizing plate of Claim 8 uses the cellulose ester film of Claim 6 or 7 for one surface, It is characterized by the above-mentioned.

Invention of the display apparatus of Claim 9 uses the cellulose-ester film of Claim 6 or 7, It is characterized by the above-mentioned.

Effect of the Invention

The invention according to claim 1, wherein the resin solution containing the cellulose ester resin is cast on the flexible support to form a cast film, the solvent in the cast film is dried until the cast film can be peeled off, and then peeled off from the cast support. It is a manufacturing method of the cellulose-ester film which obtains a cellulose-ester film by drying and winding a solvent through the extending process which grasps both ends of the peeled web, and extends to the width direction, and the elongation of the web in an extending process is 20-. It is 60%, and the temperature of the warm air which blows off from the warm air blowing means in an extending process is Tg + 35 degreeC-Tg + 80 degreeC with respect to the glass transition temperature (Tg) of the film after winding-up, It is a claim of Claim 1 According to the invention, even if high stretching, the haze of the film does not increase, the optical properties excellent in transparency and planarity, cellulose There is the effect that the hotel's film can be produced.

Invention of Claim 2 is a manufacturing method of the cellulose-ester film of Claim 1, and it is 10-35 mass% of residual solvent amount of the film immediately before entering an extending process, According to invention of Claim 2 Proper self-supportability can be ensured while further reducing the stress applied to the film.

When the temperature of the stretching step is increased as in the present invention, the amount of volatilization of organic components such as a plasticizer tends to increase, but according to the invention of claim 3, the organic component contained in the exhaust wind from the stretching step is removed. Since it has a means to make it possible, the contamination of a film by an organic component and the contamination of a film manufacturing apparatus can be prevented. Moreover, according to claim 4, since it recycles again as a part of dry wind upstream rather than an extending process, it exhibits the effect that the manufacturing cost of a cellulose ester film can be reduced.

Invention of Claim 5 is a manufacturing method of the cellulose-ester film of Claim 4, Comprising: The said removal means is connected in multiple numbers, According to invention of Claim 5, the density | concentration of the organic component in exhaust wind is Since it can reliably decrease, exhaust air can be reused more effectively as a part of dry wind upstream than an extending process again.

Invention of Claim 6 is a cellulose-ester film manufactured by the method of any one of Claims 1-3, The width | variety of the film after winding is 1650-2500mm, Claim 6 of Claim 6 According to the invention, there is an effect that a wide cellulose ester film for a liquid crystal display device can be produced.

Invention of the cellulose-ester film of Claim 7 has a film thickness of 40-80 micrometers after winding, and according to invention of Claim 7, it has the effect that it can contribute to thickness reduction of a display apparatus.

According to the invention of the polarizing plate of Claim 8, even when this is assembled to a liquid crystal display device, the effect of being excellent in visibility is exhibited without causing a fall of contrast.

According to the invention of the display device according to claim 9, it exhibits an effect of excellent visibility without causing a decrease in contrast.

BRIEF DESCRIPTION OF THE DRAWINGS The flowchart which shows the specific example of the apparatus which implements the manufacturing method of the cellulose-ester film of this invention.

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.

<Code description>

1: endless belt (flexible support)

2: flexible die

3: peeling roll

5: tenter (stretching process)

5a: warm air blowing slit (hot air blowing means)

5b: exhaust wind outlet

6: roll conveying drying device

7: conveying roll

8: winder

10: web

11: warm air (dry wind)

12: exhaust wind

13a: organic component removal device (organic component removal means)

13b: organic component removing device (organic component removing means)

14: exhaust wind

15: dry wind

16: exhaust wind

20: cellulose ester film

EMBODIMENT OF THE INVENTION Next, although embodiment of this invention is described, this invention is not limited to this.

The present invention is a state in which a resin solution (dope) containing a cellulose ester resin is cast on a flexible support made of an endless belt made of a rotary drive stainless steel, a drum made of stainless steel, or the like to form a flexible film, and the solvent in the flexible film can be peeled off. In the solution casting film forming method in which a cellulose ester film is obtained by drying and winding up to a width and then peeling from the flexible support, followed by a stretching step of gripping both ends of the peeled web and stretching in the width direction. It is a manufacturing method of the cellulose-ester film by which the elongation rate of the web in an extending process is 20 to 60%, and the temperature of the warm air which blows off from the warm air blowing means in an extending process is the glass transition temperature (Tg) of the film after winding up. ), Tg + 35 ° C to Tg + 80 ° C.

The extending process in this embodiment is the tenter system which grasps and extends the both edges of a web (or film) with a clip etc., and a warm air blowing means is a warm air blowing slit of a tenter.

In this embodiment, the resin solution (dope) containing a cellulose ester resin is a plasticizer, a retardation controlling agent, an ultraviolet absorber, microparticles | fine-particles, and at least 1 sort (s) of substance in a low molecular weight substance, a cellulose ester resin, And a solvent.

Hereinafter, these are demonstrated in detail.

A cellulose ester is a cellulose ester in which the hydroxyl group derived from cellulose was substituted by the acyl group. For example, cellulose acylate, such as cellulose acetate, cellulose triacetate, cellulose acetate propionate, cellulose acetate butyrate, cellulose acetate propionate butyrate, cellulose acetate which has aliphatic polyester graft side chain, etc. are mentioned. . Among them, cellulose acetate, cellulose acetate propionate, and cellulose acetate having aliphatic polyester graft side chains are preferable. As long as it is a range which does not impair the effect of this invention, another substituent may be included.

As an example of a cellulose triacetate, it is preferable that the substitution degree of an acetyl group is 2.0 or more and 3.0 or less. By making substitution degree into this range, favorable moldability can be obtained and desired in-plane direction retardation R0 and thickness direction retardation Rt can be obtained. When the degree of substitution of the acetyl group is lower than this range, the moist heat resistance as the retardation film, in particular, the dimensional stability under moist heat may be inferior, and when the degree of substitution is too large, the necessary retardation characteristics may not be expressed.

Although there is no limitation in particular as a cellulose of the raw material of the cellulose ester used for this invention, Cotton linter, wood pulp, kenaf, etc. are mentioned. In addition, the cellulose ester obtained from them can be mixed and used in arbitrary ratios, respectively.

In this invention, the number average molecular weight of a cellulose ester has preferable the mechanical strength of the film from which the range of 60000-300000 is obtained. Moreover, 70000-200000 are preferable.

In this specification, the organic solvent which has favorable solubility with respect to a cellulose ester film is called a good solvent, and it shows the main effect in dissolution, The solvent used in large quantities among these is called a main solvent or a main solvent.

Examples of good solvents include ketones such as acetone, methyl ethyl ketone, cyclopentanone and cyclohexanone, tetrahydrofuran (THF), 1,4-dioxane, 1,3-dioxolane and 1,2-dimethoxyethane Methyl cellosolve, dimethylimidazolinone, dimethylformamide, dimethylacetamide, in addition to esters such as ethers, methyl formate, ethyl formate, methyl acetate, ethyl acetate, amyl acetate, and γ-butyrolactone Acetonitrile, dimethyl sulfoxide, sulfolane, nitroethane, methylene chloride, methyl acetoacetate, and the like can be mentioned, but 1,3-dioxolane, THF, methyl ethyl ketone, acetone, methyl acetate and methylene chloride are preferred.

It is preferable to make dope contain 1-40 mass% C1-C4 alcohol other than the said organic solvent. They soften the dope to the flexible support, and then the solvent starts to evaporate and the proportion of alcohol increases, thereby gelling the web (the name of the dope film after the dope of the cellulose derivative is flexible on the flexible support is called a web). It is used as a gelling solvent which makes it easy to peel off from a cast support, or when these ratios are small, it also has a role which accelerates dissolution of the cellulose ester resin by a non-chlorine organic solvent.

Examples of the alcohol having 1 to 4 carbon atoms include methanol, ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol, tert-butanol, and propylene glycol monomethyl ether. Among them, ethanol is preferable because of excellent stability of the dope, relatively low boiling point, good dryness and no toxicity. These organic solvents alone do not have solubility in cellulose derivatives and are referred to as poor solvents.

The most preferable solvent is a mixed solvent having a ratio of methylene chloride: ethyl alcohol of 95: 5 to 80:20 as a solvent for dissolving cellulose ester resin, which is a preferable high molecular compound satisfying such conditions at high concentration. Alternatively, a mixed solvent of methyl acetate: ethyl alcohol 60: 40 to 95: 5 is also preferably used.

In the film according to the present invention, a plasticizer for imparting processability, flexibility and moisture resistance to the film, fine particles (mat agent) for imparting slipperiness to the film, a UV absorber for imparting ultraviolet absorption function, and an antioxidant for preventing deterioration of the film Various additives, such as these, can be mix | blended.

As the plasticizer used in the present invention, a cellulose ester resin or a polycondensate of a reactive metal compound capable of hydrolytic polycondensation and hydrogen bonding or the like interacts with the cellulose ester resin or hydrolytic polycondensation so as not to cause haze on the film, or to bleed out or volatilize it from the film. It is preferable to have a functional group as much as possible.

As such a functional group, a hydroxyl group, an ether group, a carbonyl group, ester group, a carboxylic acid residue, an amino group, an imino group, an amide group, an imide group, a cyano group, a nitro group, a sulfonyl group, a sulfonic acid residue, a phosphonyl group, a phosphonic acid residue Although these etc. are mentioned, Preferably they are a carbonyl group, ester group, and phosphonyl group.

Examples of such plasticizers include phosphate ester plasticizers, phthalic ester plasticizers, trimellitic acid ester plasticizers, pyromellitic acid plasticizers, polyhydric alcohol ester plasticizers, glycolate plasticizers, citric acid ester plasticizers and fatty acid ester plasticizers. , Carboxylic acid ester plasticizers, polyester plasticizers and the like can be preferably used, but are particularly preferably non-phosphate ester plasticizers such as polyhydric alcohol ester plasticizers, glycolate plasticizers, and polyhydric carboxylic acid ester plasticizers. .

It is preferable that a polyhydric alcohol ester contains the ester of a bivalent or more aliphatic polyhydric alcohol and a monocarboxylic acid, and has an aromatic ring or a cycloalkyl ring in a molecule | numerator. This polyhydric alcohol is represented by following General formula (1).

R1- (OH) n

(Wherein R1 is an n-valent organic group and n represents a positive integer of 2 or more)

As an example of a preferable polyhydric alcohol, although the following is mentioned, for example, this invention is not limited to this.

Examples of preferred polyhydric alcohols include adonitol, arabitol, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propanediol, dipropylene glycol, tripropylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, dibutylene glycol, 1,2,4-butanetriol, 1,5-pentanediol, 1,6-hexanediol, hexanetriol , Galactitol, mannitol, 3-methylpentane-1,3,5-triol, pinacol, sorbitol, trimethylolpropane, trimethylolethane, xylitol and the like. In particular, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, sorbitol, trimethylol propane and xylitol are preferable.

There is no restriction | limiting in particular as monocarboxylic acid used for polyhydric alcohol ester, Well-known aliphatic monocarboxylic acid, alicyclic monocarboxylic acid, aromatic monocarboxylic acid, etc. can be used. When alicyclic monocarboxylic acid and aromatic monocarboxylic acid are used, it is preferable at the point which improves moisture permeability and retention property.

Although the following are mentioned as an example of a preferable monocarboxylic acid, This invention is not limited to this.

As the aliphatic monocarboxylic acid, a fatty acid having a straight or branched chain having 1 to 32 carbon atoms can be preferably used. As for carbon number, it is more preferable that it is 1-20, and it is especially preferable that it is 1-10. When acetic acid is contained, since compatibility with cellulose ester resin increases, it is also preferable, and it is also preferable to mix acetic acid and another monocarboxylic acid.

Examples of preferred aliphatic monocarboxylic acids include acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelagonic acid, capric acid, 2-ethyl-hexanecarboxylic acid, undecyl acid, lauric Acid, tridecyl acid, myristic acid, pentadecyl acid, palmitic acid, heptadecyl acid, stearic acid, nonadecanoic acid, arachic acid, behenic acid, lignoseric acid, serotic acid, heptaconic acid, montanic acid, Saturated fatty acids, such as melisic acid and lacseric acid, unsaturated fatty acids, such as undecylenic acid, oleic acid, sorbic acid, linoleic acid, linolenic acid, and arachidonic acid, etc. are mentioned.

Cyclopentanecarboxylic acid, cyclohexane carboxylic acid, cyclooctane carboxylic acid, or derivatives thereof are mentioned as an example of a preferable alicyclic monocarboxylic acid.

As an example of a preferable aromatic monocarboxylic acid, the thing which introduce | transduced the alkyl group into the benzene ring of benzoic acid, such as benzoic acid and toluic acid, and two benzene rings, such as biphenylcarboxylic acid, naphthalene carboxylic acid, and tetralin carboxylic acid Although aromatic monocarboxylic acid or derivatives thereof which have the above are mentioned, Especially benzoic acid is preferable.

Although the molecular weight of polyhydric alcohol ester does not have a restriction | limiting in particular, It is preferable that it is 300-1500, It is more preferable that it is 350-750. Since the larger molecular weight becomes difficult to volatilize, it is preferable, and the smaller one is preferable at the point of moisture permeability and compatibility with a cellulose ester resin.

The carboxylic acid used for a polyhydric alcohol ester may be one type, or 2 or more types of mixtures may be sufficient as it. In addition, all the OH groups in a polyhydric alcohol may be esterified and a part may be left in OH group state.

Although a glycolate plasticizer is not specifically limited, The glycolate plasticizer which has an aromatic ring or a cycloalkyl ring in a molecule | numerator can be used preferably. As a preferable glycolate plasticizer, butylphthalyl butyl glycolate, ethyl phthalyl ethyl glycolate, methyl phthalyl ethyl glycolate, etc. can be used, for example.

Examples of the phosphate ester plasticizer include triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, diphenyl biphenyl phosphate, trioctyl phosphate and tributyl phosphate. Phthalate, dimethoxyethyl phthalate, dimethyl phthalate, dioctyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate, dicyclohexyl phthalate, etc. can be used.

These plasticizers can be used individually or in mixture of 2 or more types.

As for the usage-amount of a plasticizer, 1-20 mass% is preferable. 6-16 mass% is more preferable, Especially preferably, it is 8-13 mass%.

In order to provide slipperiness | lubricacy, it is preferable to add microparticles | fine-particles, such as a mat agent, to the cellulose ester resin in this invention. As microparticles | fine-particles, the microparticles | fine-particles of an inorganic compound or the microparticles | fine-particles of an organic compound are mentioned.

As an example of microparticles | fine-particles of an inorganic compound, microparticles | fine-particles, such as a silicon dioxide, titanium dioxide, aluminum oxide, a zirconium oxide, tin oxide, are mentioned. In this, it is preferable that they are microparticles | fine-particles of the compound containing a silicon atom, and especially silicon dioxide microparticles | fine-particles are preferable. As silicon dioxide microparticles | fine-particles, AEROSIL 200, 200V, 300, R972, R972V, R974, R202, R812, R805, OX50, TT600 etc. by Aerosil Co., Ltd. are mentioned, for example.

As an example of microparticles | fine-particles of an organic compound, microparticles | fine-particles, such as an acrylic resin, a silicone resin, a fluoro compound resin, and a urethane resin, are mentioned.

Although the primary particle diameter of microparticles | fine-particles is not specifically limited, Finally, about 0.05-5.0 micrometers is preferable for the average particle diameter in a film. More preferably, it is 0.1-1.0 micrometer.

The average particle diameter of microparticles | fine-particles shows the average value of the length of the long-axis direction of particle | grains in the observation place of a film, when a cellulose ester film is observed with an electron microscope or an optical microscope. As long as it is a particle | grains observed in a film, a primary particle may be sufficient and the secondary particle which the primary particle aggregated may be sufficient, but the majority observed normally are secondary particle | grains.

As for dispersion of microparticles | fine-particles, it is preferable to process the composition which mixed microparticles | fine-particles and a solvent with a high pressure dispersion apparatus. The high pressure dispersing device is a device that creates special conditions such as high shear and high pressure by passing a composition in which fine particles and a solvent are mixed at high speed in tubules.

As a high pressure dispersing apparatus as mentioned above, the ultra-high pressure homogenizer (brand name microfluidizer) by the Microfluidics Corporation company, or the nanomizer of the nanomizer company is mentioned, for example, In addition, a mantongorin type high pressure dispersing apparatus, for example And homogenizers manufactured by Izumi Food Machinery Co., for example.

In this invention, microparticles | fine-particles are disperse | distributed in the solvent containing 25-100 mass% of lower alcohols, and are mixed with the dope which melt | dissolved the cellulose ester resin in the solvent.

Here, as a content rate of lower alcohol, Preferably it is 50-100 mass%, More preferably, it is 75-100 mass%.

Moreover, as an example of lower alcohols, Preferably, methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol, etc. are mentioned.

Although it does not specifically limit as solvent other than lower alcohol, It is preferable to use the solvent used at the time of film forming of a cellulose ester.

It is preferable that the ultraviolet absorber is contained in various optical films, such as a polarizing plate protective film, retardation film, and an optical compensation film, from a viewpoint of prevention of deterioration.

As a ultraviolet absorber, the thing which is excellent in the absorption ability of the ultraviolet-ray of wavelength 370nm or less from a viewpoint of prevention of deterioration of a polarizer and a liquid crystal, and from the viewpoint of liquid crystal display property is preferable that there is little absorption of visible light of wavelength 400nm or more.

In this embodiment, as a ultraviolet absorber which can be used, For example, an oxybenzo phenone type compound, a benzotriazole type compound, a salicylic acid ester type compound, a benzophenone type compound, a cyanoacrylate type compound, a nickel complex salt type compound, etc. Although the benzotriazole type compound with few coloring is preferable. In addition, the ultraviolet absorber of Unexamined-Japanese-Patent No. 10-182621, Unexamined-Japanese-Patent No. 8-337574, and the polymeric ultraviolet absorber of Unexamined-Japanese-Patent No. 6-148430 are also used preferably.

Specific examples of useful ultraviolet absorbers include 2- (2'-hydroxy-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5'-di-tert-butylphenyl) benzotriazole , 2- (2'-hydroxy-3'-tert-butyl-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5'-di-tert-butylphenyl) -5 -Chlorobenzotriazole, 2- (2'-hydroxy-3 '-(3 ", 4", 5 ", 6" -tetrahydrophthalimidomethyl) -5'-methylphenyl) benzotriazole, 2,2 -Methylene bis (4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol, 2- (2'-hydroxy-3'-tert-butyl -5'-methylphenyl) -5-chlorobenzotriazole, 2- (2H-benzotriazol-2-yl) -6- (straight and branched dodecyl) -4-methylphenol, octyl-3- [3- tert-butyl-4-hydroxy-5- (chloro-2H-benzotriazol-2-yl) phenyl] propionate and 2-ethylhexyl-3- [3-tert-butyl-4-hydroxy-5 Although a mixture of-(5-chloro-2H-benzotriazol-2-yl) phenyl] propionate, etc. are mentioned, It is not limited to these.

Moreover, as a commercial item of a ultraviolet absorber, TINUVIN 109, TINUVIN 171, and TINUVIN 326 (all are the Ciba specialty chemicals company make) can be used preferably.

Moreover, as a specific example of the benzophenone type compound which is an ultraviolet absorber which can be used in this invention, 2, 4- dihydroxy benzophenone, 2, 2'- dihydroxy-4- methoxy benzophenone, 2-hydride Hydroxy-4-methoxy-5-sulfobenzophenone, bis (2-methoxy-4-hydroxy-5-benzoylphenylmethane), and the like, but are not limited thereto.

In this invention, the range of 0.01-10 mass% is preferable with respect to a cellulose ester (cellulose derivative), and, as for the compounding quantity of these ultraviolet absorbers, 0.1-5 mass% is preferable. When the usage-amount of a ultraviolet absorber is too small, the ultraviolet absorbing effect may be inadequate, and when there are too many ultraviolet absorbers, since transparency of a film may deteriorate, it is unpreferable. It is preferable that a ultraviolet absorber has high thermal stability.

Moreover, the ultraviolet absorber which can be used for the cellulose-ester film of this embodiment also mentions the polymeric ultraviolet absorber (or ultraviolet absorbent polymer) of Unexamined-Japanese-Patent No. 6-148430 and 2002-47357. have. In particular, the polymeric ultraviolet absorber represented by the general formula (1) or the general formula (2) or the general formula (3), the general formula (6) and the general formula (7) described in Japanese Patent Laid-Open No. 6-148430 is preferably used. .

Although antioxidant is generally called deterioration inhibitor, it is preferable to make it contain in the cellulose ester film as an optical film. That is, when a liquid crystal image display device etc. are put in the state of high humidity high temperature, deterioration of the cellulose ester film as an optical film may generate | occur | produce. Since antioxidant has a role which delays or prevents decomposition of a film, for example by halogen in the residual solvent in a film, phosphoric acid of a phosphate plasticizer, etc., it is preferable to contain it in a film.

As such an antioxidant, a hindered phenol type compound is preferably used, for example, 2,6-di-t-butyl-p-cresol, pentaerythryl-tetrakis [3- (3,5- Di-t-butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6 -Hexanediol-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], 2,4-bis- (n-octylthio) -6- (4-hydroxy -3,5-di-t-butylanilino) -1,3,5-triazine, 2,2-thio-diethylene bis [3- (3,5-di-t-butyl-4-hydroxy Phenyl) propionate], octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, N, N'-hexamethylene bis (3,5-di-t- Butyl-4-hydroxy-hydrocinnamid), 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, tris- (3 , 5-di-t-butyl-4-hydroxybenzyl) -isocyanurate and the like. In particular 2,6-di-t-butyl-p-cresol, pentaerythryl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], triethylene Glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate] is preferred.

Further, for example, hydrazine-based metal deactivators such as N, N'-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyl] hydrazine and tris (2,4-di You may use together phosphorus process stabilizers, such as -t- butylphenyl) phosphite.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of the cellulose ester film which concerns on this invention is described in detail. A film can be produced by the solution casting film forming method.

BRIEF DESCRIPTION OF THE DRAWINGS It is a flow sheet which shows the specific example of the apparatus which performs the manufacturing method of the cellulose-ester film by the solution casting film forming method. In addition, in implementation of this invention, it is not limited to the process of the drawing shown below.

First, in a melting kiln not shown, the cellulose ester resin is dissolved in a mixed solvent of a good solvent and a poor solvent, and the plasticizer and the ultraviolet absorber described above are added thereto to prepare a resin solution (dope).

In Fig. 1, the dope continuously adjusted in the melting kiln is fed to the casting die 2 by a conduit via, for example, a pressurized metering gear pump, and the casting die is placed in the casting position on the casting belt 1 at the casting die. Dope from (2) is flexible. The flexible belt 1 corresponds to the flexible support of the present invention, and is an endless belt made of stainless steel that is rotationally driven and shifts to infinity.

In the casting of the dope by the casting die 2, there is a doctor blade method of adjusting the film thickness of the flexible dope film (web) by the blade, or a method of a reverse roll coater of adjusting the roller of the reverse rotation. The press die which can manufacture the slit shape of a member part and is easy to make a film thickness uniform is preferable. Although there exist a coating hanger die, a T die, etc. in pressurization die | dye, all are used preferably.

The flexible belt 1 is interposed between a pair of drums, and supports the upper transition part and the lower transition part in the middle with the some roll (not shown), respectively from the back surface.

One or both of the drums of the windings of the both ends of the flexible belt 1 are provided with a driving device for applying tension to the flexible belt 1, whereby the flexible belt 1 is used in a tensioned and pulled state. .

In addition, in this embodiment, in order to ensure 1650-2500mm as a width | variety of the film after winding, the casting | flow_spread width of 2000-2500mm and the casting width of a cellulose ester solution are 1900-2480mm. Thereby, a wide cellulose ester film for liquid crystal display devices can be manufactured by a flexible support system.

Here, if the width | variety of the flexible support body 1, the casting width of a cellulose-ester solution, and the width | variety of the film after winding are each more than the said lower limit, it can respond to the enlargement of the liquid crystal display device in recent years.

Moreover, if the width | variety of the flexible belt 1, the flexible width of a cellulose-ester solution, and the width of the film after winding are respectively below an upper limit, even if the amount of residual solvent of the film after peeling is large, the film will fall down or stretch Unevenness does not occur.

In addition, in this embodiment, the circumferential speed of the flexible belt 1 shall be 80-200 m / min.

That is, by making the circumferential speed of the flexible belt 1 faster than the conventional drum circumferential speed, the production speed of the film can be increased, and the productivity of the cellulose ester film can be increased.

As the temperature of the flexible belt 1 at the time of film forming, it can be flexible at the temperature below the boiling point of a general temperature range 0 degreeC-a solvent, and the mixing solvent at the temperature below the boiling point of the solvent with the lowest boiling point, Furthermore, 5 degreeC-a solvent boiling point The range of -5 degreeC is more preferable.

The dope cast on the surface of the flexible belt 1 as described above increases the strength (film strength) of the gel film by cooling gelation, and also increases the strength (film strength) of the gel film by promoting drying during the peeling. Increases.

In addition, in order to increase the film forming speed, two or more press-casting dies 12 may be provided on the flexible belt 1 for casting, and the dope amount may be divided to form a middle layer.

On the flexible belt 1, since the web 10 is dried and solidified until it becomes the film strength which can be peeled off with the peeling roll 16 from the flexible belt 1, the amount of residual solvent in the web 10 is 150 mass% or less. It is preferable to dry, and 80-120 mass% is more preferable. Moreover, as for the web temperature at the time of peeling the web 10 from the flexible belt 1, 0-30 degreeC is preferable. In addition, immediately after peeling from the flexible belt 1, the web 10 has a temperature rapidly decreased by solvent evaporation from the flexible belt 1 contact surface side, and volatile components such as water vapor and solvent vapor in the atmosphere are condensed. Since it is easy to carry out, 5-30 degreeC of the web temperature at the time of peeling is more preferable.

Here, the residual solvent amount can be expressed by the following equation.

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

In formula, M is mass at arbitrary time points of a web, N is mass when the thing of mass M is dried at 110 degreeC for 3 hours.

In addition, the elongation can be expressed by the following equation.

When the distance between clips in front of the tenter 5 in the stretching step is h, and the distance between clips at the end of the tenter 5 in the stretching step is H,

Elongation = H / h × 100%

The dope film (web) formed by the dope cast on the flexible belt 1 is heated on the flexible belt 1 until the web can be peeled off from the flexible belt 1 by the peeling roll 3. Evaporate the solvent.

In order to evaporate a solvent, there exists a method of blowing air from the web side, and / or the method of heat-transferring from the back surface of the flexible belt 1 with a liquid, the method of heat-transferring from front and back by radiant heat, etc.

At the time of peeling, since the film is easy to stretch in the conveying direction and easily shrinks in the width direction, the peeling tension when peeling the web 10 from the flexible belt 1 with the peeling roll 3 can be peeled off. It is preferable to peel at the minimum tension to 170 N / m, and more preferably to peel at the minimum tension to 140 N / m.

After drying and solidifying until the web 10 becomes the peelable film strength on the flexible support body 1, the web 10 is peeled off with the peeling roll 3, and in the tenter 5 of the extending process subsequently, The web 10 is stretched.

It is preferable that the amount of residual solvent of the web (film) 10 just before entering the tenter 5 of an extending process is 10-35 mass%.

In the stretching step, the warm air 11 blows in from the warm air ejection means of the front side portion of the bottom of the tenter 5, that is, the warm air ejection slit port 5a, and the exhaust port of the rear side portion of the ceiling of the tenter 5 ( By exhausting the exhaust wind 12 from 5b), the web 10 is stretched and dried.

In addition, although the warm air blowing slit 5a of the tenter 5 of an extending process respond | corresponds specifically to the warm air blowing means in the extending process in this invention, a film is efficiently blown by the blowing of a warm air. It will not specifically limit, if it is a shape to heat. For example, the same thing as a slit shape or punch plate shape shown in the figure is mentioned.

In this invention, the elongation rate of the web in the tenter 5 of an extending process is 20 to 60%, and the temperature of the warm air 11 which blows off from the warm air blowing slit 5a in the tenter 5 is About the glass transition temperature (Tg) of the film after winding up, it is set as Tg + 35 degreeC-Tg + 80 degreeC. Moreover, it is more preferable that the said temperature is Tg + 40 degreeC-Tg + 50 degreeC.

Here, when the elongation of the web 10 in the tenter 5 of an extending process is less than a lower limit, since a wide film cannot be obtained, it is not preferable. In addition, when the elongation of the web 10 in the tenter 5 exceeds the upper limit, the haze of the film rises and the light transmittance decreases. Therefore, when assembled to the liquid crystal display device, the contrast decreases, which is not preferable. not.

When the temperature of the warm air 11 ejected from the warm air jet slit port 5a in the tenter 5 of the stretching step is less than the lower limit, unreasonable stress is applied to the film at the time of stretching. Since transmittance | permeability falls, since contrast falls when assembled to a liquid crystal display device, it is unpreferable. In addition, when the temperature of the warm air 11 ejected from the warm air ejection slit port 5a in the tenter 5 exceeds the upper limit, the film softens and loses self-support. Since it is torn, it is not preferable.

Here, when the temperature of the warm air 11 in the tenter 5 of an extending process is Tg + 35 degreeC or more, since a wide film can be obtained, it is preferable. Moreover, when the temperature of the warm air 11 in the tenter 5 of an extending process is Tg + 80 degreeC or less, the haze of a film does not rise, the light transmittance is high, and when it is assembled to a liquid crystal display device, the contrast falls It is preferable because it can prevent.

In the drying process after peeling from the casting belt 1, the web (or film) 10 tries to shrink | contract in the width direction by evaporation of a solvent. Drying at high temperatures results in greater shrinkage. Drying while suppressing this shrinkage as much as possible is preferable from the viewpoint of improving the planarity of the finished film.

It is preferable to perform these width retention or extending | stretching of the lateral direction by the tenter 5, a pin tenter may be sufficient, and a clip tenter may be sufficient as it.

In this embodiment, for example, two organic component removal apparatuses (removal means) which remove the low molecular weight organic component (plasticizer etc.) contained in the exhaust air 12 from the tenter 5 of an extending process ( 13a) and 13b, and the organic component density | concentration in the exhaust wind 14 after having passed these organic component removal apparatus 13a, 13b is 1-100 micrograms / m <3>.

In addition, in this embodiment, the exhaust wind 14 from which the organic component was removed by the organic component removal apparatus 13a, 13b is again part of warm air upstream than the tenter 5 of an extending process, ie, a part of the drying wind 11. It is reused as. In addition, although the organic component removal apparatus 13a (13b) has shown two groups, what is necessary is just multiple stages, for example, that the organic component removal apparatus 13a (13b) of 2-4 groups is connected, for example. desirable.

After the tenter 5 of the stretching step, the post-drying device 6 is provided. In the post-drying apparatus 6, the web 10 meanders by the some conveyance roll 7 staggered from the side, and the web 10 dries during this time. In addition, although the film conveyance tension in the after-drying apparatus 6 is influenced by the physical property of dope, the time of peeling, the residual solvent quantity in a film conveyance process, the temperature in the after-drying apparatus 6, etc., it is 30-250 N / m Is preferable, and 60-150 N / m is more preferable. Most preferred is 80 to 120 N / m.

In addition, the means for drying the web (or film) 10 is generally performed by hot air, infrared rays, a heating roll, a microwave, etc. without a restriction | limiting in particular. It is preferable to dry by hot air from the point of simplicity, for example, it is dried by the drying wind 15 blown in from the warm air inlet of the front side part of the bottom of the after-drying apparatus 6, and the after-drying apparatus 6 The exhaust wind 16 is dried by discharging from the outlet of the rear side portion of the ceiling. 40-160 degreeC is preferable and, as for the temperature of the drying wind 15, since 50-160 degreeC improves planarity and dimensional stability, it is more preferable.

The process from these casting to post-drying may be in an air atmosphere, or may be inert gas atmosphere, such as nitrogen gas. In this case, it goes without saying that the drying atmosphere is carried out in consideration of the explosion limit concentration of the solvent.

The web conveyance tension at the time of drying is 30-300 N / width m, and 40-270 N / width m is more preferable.

After the process from casting to post-drying, it is preferable that a cleansing device on the surface of the web 10 is arranged.

The cleaning device applies ultrasonic vibrations to the web 10 in the middle of conveyance, blows high-pressure winds onto the surface, blows off the adherends, and removes dust and the like. In addition, well-known means and methods, such as a method of performing flame treatment (corona treatment and plasma treatment) and a method of providing an adhesive roll, can be used without particular limitation. In addition, the cleaning means to arrange | position may be single, and two or more may be sufficient as it.

Since adhesion of dust and the like to the web 10 is often caused by the action of static electricity, it is preferable to dispose static electricity means, for example, a static electricity bar, before the above-described cleaning device to remove the static electricity of the web 10. . As the antistatic bar, known ones can be used without particular limitation.

In the drying step, as a countermeasure for suppressing the phenomenon that the plasticizer contained in the web 10 evaporates and condenses on the roll or the wall surface, it is preferable to introduce a fresh gas of a specific amount or more with respect to the amount of supply air per unit time. And it is preferable to set the quantity of the fresh gas to supply to 5 to 50% of the total supply air volume.

The fresh gas supply is set at 5 to 50% because less than 5% of the fresh gas is too small to completely suppress plasticizer condensation. Because there are many.

In order to prevent the elongation of the film in the post-drying apparatus 6 to the conveyance direction, it is preferable to provide a tension cut roll. It is preferable to install a slitter after the end of drying and cut off the end portion before winding up in order to obtain a good winding form.

About the cellulose-ester film which completed the post-drying process (6), in the front end introduce | transduced into a winding process, the process which forms embossing on a film by an embossing processing apparatus is performed.

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

As for the width of the embossing, the embossing part is ultimately a loss part, so it is desired to be less. For example, a thin film film within 50 μm, the minimum required embossing width for suppressing the sliding of the film at the time of high-speed film formation of 50 m / min or more to be. However, it is also linked with the height of the embossing mentioned above, and the embossing height x embossing width which clears all of a pyramid shape, a mountain ridge shape, a polygon shape, and a winding error failure is determined. In addition, embossing can be arrange | positioned not only in the both ends of a film but a center part part.

In this invention, it is preferable to install a static eliminator before winding up and just after a winding part, and to electrostatically remove a film.

The static eliminator can be configured in such a manner that the reverse potential is imparted by the antistatic device or the forced charging device at the time of winding so that the charging potential when the original winding body is unwound becomes ± 2 KV or less. It can also be set as the structure which static electricity charges by the static electricity converter which converts by the government.

In place of the aforementioned static eliminator, an ionizer or an antistatic bar that generates ion wind can be used. Here, ionizer static elimination is performed by blowing ion wind toward the film wound up from a embossing apparatus past a conveyance roll. Ionic wind is generated by the static eliminator. As a static eliminator, a well-known thing can be used without a restriction | limiting.

In the process of winding up the film 20 after drying by the winding apparatus 8, and obtaining the original winding body of an optical film, the amount of residual solvent of the film 20 which complete | finishes drying is 0.5 mass% or less, Preferably By setting it as 0.1 mass% or less, the film with favorable dimensional stability can be obtained.

As the winding method of the film, a winder which is generally used may be used, and there are methods of controlling tension such as the constant torque method, the constant tension method, the tapered tension method, and the program tension control method with constant internal stress. You can use

 Bonding of the film to the winding core (winding core) may be either a double-sided adhesive tape or a single-sided adhesive tape.

It is preferable that the width | variety of the film after winding up in the cellulose-ester film which concerns on this invention is 1650-2500 mm.

In the present invention, the film thickness after drying of the cellulose ester film is preferably in the range of 40 to 80 µm from the viewpoint of thinning of the liquid crystal display device as the finished film. Here, the film thickness after drying means the film of the state whose amount of residual solvent in a film is 0.5 mass% or less.

Here, when the film thickness of the cellulose-ester film after winding is too thin, the required intensity | strength as a protective film for polarizing plates may not be obtained, for example. If the film thickness of the film is too thick, the advantage of thinning of the conventional cellulose ester film is lost. For adjusting the film thickness, it is preferable to control the dope concentration, the amount of pumped liquid, the slit gap of the inlet metal member of the cast die, the extrusion pressure of the cast die, the speed of the cast support, and the like so as to have a desired thickness. Further, as means for making the film thickness uniform, it is preferable to feed back the programmed feedback information to each of the above apparatuses by using the film thickness detecting means.

In the process from immediately after casting to drying through the solution casting film forming method, the atmosphere in the drying apparatus may be air, but may be performed in an inert gas atmosphere such as nitrogen gas or carbon dioxide gas. However, of course, the risk of explosion limit of the evaporating solvent in the dry atmosphere must always be considered.

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

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

In addition, the cellulose ester film produced by the method of the present invention has a haze of 0.3 to 2.0 when three sheets are stacked, and according to the cellulose ester film of the present invention, the haze of the film is very low and is excellent in transparency and planarity. It has optical properties.

In this embodiment, in-plane direction retardation R0 defined by the following formula is 30-300 nm and thickness direction retardation Rt at the temperature of 23 degreeC, and 55% of humidity under conditions of temperature 23 degreeC and 55% RH of humidity. It is set to 70-400 nm under the conditions of RH.

R0 = (nx-ny) × d

Rt = {(nx + ny) / 2-nz} × d

[Wherein R0 is a film in-plane retardation value, Rt is a film thickness direction retardation value, nx is a refractive index in the slow axis direction in the film plane, ny is a refractive index in the fast axis direction in the film plane, nz is a film thickness direction Refractive index (refractive index measured at wavelength 590nm), d denotes thickness of film (nm)]

In addition, retardation value R0 and Rt can be measured using an automatic birefringence meter. For example, using KOBRA-21ADH (manufactured by Oji Scientific Instruments Co., Ltd.), the wavelength can be obtained at 590 nm under an environment of a temperature of 23 ° C. and a humidity of 55% RH.

It is preferable that the cellulose-ester film manufactured by the method of this invention is used for the member for liquid crystal displays, specifically, the protective film for polarizing plates. In particular, in the protective film for polarizing plates which have strict requirements on both moisture permeability and dimensional stability, the cellulose ester film produced by the method of the present invention is preferably used.

By using the protective film for polarizing plates which consist of the cellulose ester film of this embodiment, a polarizing plate excellent in durability, dimensional stability, and optical isotropy can be provided with thinning.

By the way, a polarizing film is what has conventionally been used, for example, the film which can be extended | stretched orientable like a polyvinyl alcohol film, is lengthwise stretched by treating with dichroic dye like iodine. Since the polarizing film itself does not have sufficient strength and durability, a cellulose ester film without anisotropy as a protective film is generally bonded to both surfaces thereof to form a polarizing plate.

In the said polarizing plate, you may bond and manufacture the cellulose-ester film manufactured by the method of this invention as retardation film, and also serve as a retardation film and a protective film directly to the cellulose-ester film manufactured by the method of this invention, You may join and manufacture. Although the method to bond is not specifically limited, It can carry out by the adhesive agent which consists of aqueous solution of a water-soluble polymer.

As this water-soluble polymer adhesive, the fully saponified polyvinyl alcohol aqueous solution is used preferably. Moreover, a long polarizing plate can be obtained by extending | stretching in the longitudinal direction and bonding the long polarizing film processed by the dichroic dye and the retardation film manufactured by the long method of this invention. The polarizing plate can be easily adhered to a liquid crystal cell by peeling off a peelable sheet on one or both surfaces thereof through a pressure-sensitive adhesive layer (for example, an acrylic pressure-sensitive adhesive layer or the like). Can be attached).

The polarizing plate obtained in this way can be used for various display devices. In particular, a liquid crystal display using a VA mode in which the liquid crystal molecules are substantially vertically aligned when no voltage is applied, or a TN mode liquid crystal cell in which the liquid crystal molecules are substantially horizontally torsionally aligned when no voltage is applied is preferable.

By the way, a polarizing plate can be produced by a general method. For example, a method of bonding an optical film or a cellulose ester film to an alkali saponification process and bonding a polyvinyl alcohol film into an iodine solution by using a fully saponified polyvinyl alcohol aqueous solution on both surfaces of the polarizing film produced. have. The alkali saponification treatment refers to a treatment in which a cellulose ester film is immersed in a high temperature strong alkaline liquid in order to improve the wettability of the aqueous adhesive and to improve adhesiveness.

The cellulose ester film produced by the method of the present embodiment includes a hard coating layer, an antiglare layer, an antireflection layer, an antifouling layer, an antistatic layer, a conductive layer, an optical anisotropic layer, a liquid crystal layer, an alignment layer, an adhesive layer, an adhesive layer, an undercoat layer, and the like. Various functional layers of can be provided. These functional layers can be formed by a method such as coating or vapor deposition, sputtering, plasma CVD, atmospheric pressure plasma treatment, or the like.

The polarizing plate obtained in this way is provided in one side or both sides of a liquid crystal cell, and a liquid crystal display device is obtained using this.

In the present invention, the liquid crystal display device comprises two sheets of a liquid crystal cell in which rod-shaped liquid crystal molecules are sandwiched by a pair of glass substrates, a polarizing film arranged to sandwich the liquid crystal cell, and a transparent protective layer disposed on both sides thereof. It has a polarizing plate.

By using the protective film for polarizing plates which consist of a cellulose ester film manufactured by the method of this invention, a polarizing plate excellent in durability, dimensional stability, and optical isotropy can be provided with thinning. Moreover, the liquid crystal display device using this polarizing plate or retardation film can maintain stable display performance over a long period of time.

The cellulose ester film manufactured by the method of this embodiment can be used also as a base material of the antireflection film or the optical compensation film.

<Example>

Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited to this.

<Example 1>

(Dope composition 1)

100 parts by mass of cellulose triacetate

(Mn = 148000, Mw = 310000, Mw / Mn = 2.1)

8 parts by mass of triphenylphosphate

2 parts by mass of ethyl phthalyl ethyl glycolate

Methylene chloride 440 parts by mass

40 parts by mass of ethanol

Tinuvin 109 (product of Ciba specialty chemicals company) 0.5 mass part

Tinuvin 171 (product of Ciba specialty chemicals company) 0.5 mass part

0.2 parts by mass of aerosil 972V (made by Nippon Aerosil Kabuki Kaisha)

The above materials were sequentially placed in a sealed container, the temperature in the container was raised from 20 ° C to 80 ° C, and then stirred for 3 hours while the temperature was kept at 80 ° C to completely dissolve the cellulose triacetate. Thereafter, stirring was stopped, and the liquid temperature was lowered to 43 ° C. This dope was filtered using filter paper (manufactured by Azumi Rossi Co., Ltd., Azumi Rossi No. 244) to obtain dope.

The dope prepared as mentioned above was uniformly cast on the support body 1 which consists of an endless belt of the drive rotation stainless steel which has a mirror-treated surface using the flexible support body type solution casting film forming apparatus shown in FIG. The dope film (web) formed by casting | flow_spread is dried on the support body 1, and the web reaches the lower surface of the support body which consists of an endless belt, and the web (film) is carried out by the peeling roll 3 at the time of turning about once. 10) was peeled from the support 1.

Subsequently, the web 10 after peeling is introduced into the tenter 5, the web 10 is inserted while clipping both ends of the web with a clip, and the hot air 11 at 160 ° C. is dried while maintaining the width, thereby drying the web 10. It extended in the width direction.

Here, the amount of residual solvent of the web (film) 10 just before entering the tenter 5 of an extending process was 12 mass%.

And the elongation rate of the web in the tenter 5 of an extending process was made into 20%, and the temperature of the warm air 11 which blows off from the warm air blowing slit 5a in the tenter 5 was 160 degreeC. . Here, the temperature of the warm air 11 in the tenter 5 was Tg + 35 degreeC with respect to the glass transition temperature of the cellulose triacetate film after winding up: Tg = 125 degreeC.

Moreover, in this Example, it has two continuous organic component removal apparatus 13a, 13b which removes organic components other than the solvent contained in the exhaust air 12 from the tenter 5, These organic component removal apparatuses The low molecular weight organic component concentration in the exhaust wind 14 after passing through (13a) and (13b) was 20 µg / m 3.

In addition, the measurement of the organic component contained in the exhaust wind 12 of the tenter 5 sampled a fixed volume of exhaust wind air, and analyzed by GC / MS in the sealed state.

In this way, the exhaust air 14 from which the organic component was removed by the organic component removal devices 13a and 13b was reused again as part of the warm air 11 upstream from the tenter 5.

Thereafter, the web (film) 10 is dried by a drying air 15 at 100 ° C. in a roll conveying drying apparatus 6 that is arranged in a zigzag manner and is provided with a plurality of mirror surface conveying rolls 7 when viewed from the side. I was. The film 20 after drying was wound up by the winding device 8 to finally obtain a cellulose triacetate film 20 having a film thickness of 80 μm and a film width of 1860 mm.

Moreover, embossing is performed to the width direction both ends of the cellulose acetate film wound up by a winding roll, the height of the convex part by embossing is made into the range of 4-12 micrometers, and the difference of the height of the convex part by embossing is 2 It was made into the micrometer or less.

An antistatic blower was used as a means to remove or reduce the surface potential of the cellulose acetate film at the time of winding.

In Table 1 below, the hot air jetted from the kind of dope composition used for the production of the cellulose triacetate film, the elongation (%) of the web 10, and the warm air jet slit 5a in the tenter 5 of the stretching step ( 11), the glass transition temperature (Tg) (° C.) of the cellulose triacetate film after the winding, the amount of residual solvent (%) added to the web 10 immediately before entering the tenter 5, and the film thickness ( Μm).

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

Here, the haze of the cellulose triacetate film was measured as follows. That is, the film produced by casting a flexible film is sampled at random from 10 places, and it uses a cellulose tree using a haze meter (1001DP type, the Nippon Denshoku Kogyo Co., Ltd. make) according to the method prescribed | regulated to JISK6714. Haze was measured by stacking three acetate films.

<Examples 2 to 15>

In the same manner as in Example 1, the cellulose triacetate film was produced using the dope composition 1, but in each of the examples, part of the film forming conditions was different as follows.

First, in Example 2, although the conditions were substantially the same as the case of Example 1, the elongation of the web 10 in the tenter 5 of an extending process was changed to 30 (%).

In Example 3 and Example 4, although the conditions were substantially the same as that of Example 1 and Example 2, the temperature of the warm air 11 which blows off from the warm air blowing slit opening 5a in the tenter 5 is 170. Change to ° C.

In Example 5 and Example 6, although the conditions were substantially the same as that of Example 1 and Example 2, the temperature of the warm air 11 was changed to 180 degreeC.

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

In Example 8, although the conditions were substantially the same as those in Example 7, the elongation of the web 10 was changed to 55 (%), and the amount of residual solvent added to the web 10 immediately before entering the tenter 5 was determined. Was changed to 35 (%).

In Example 9, although the conditions were substantially the same as the case of Example 7, the temperature of the warm air 11 was changed to 200 degreeC.

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

In Example 11, although it was made into substantially the same conditions as Example 10, the elongation of the web 10 was changed to 60 (%).

In Example 12 and Example 13, although the conditions were substantially the same as the case of Example 6, the amount of residual solvent of the web 10 just before entering the tenter 5 was changed into 20 mass% and 35 mass%.

In Example 14 and Example 15, although the conditions were substantially the same as the case of Example 6, the film thickness of the film was changed to 40 micrometers and 60 micrometers, respectively.

<Comparative Example 1 to Comparative Example 6>

For comparison, the cellulose triacetate film was produced using the dope composition 1 of Example 1, but the difference from the case of Example 1 was that in the tenter 5 in Comparative Example 1 and Comparative Example 6 The elongation (%) of the web 10 was set to 18% and 65% outside the scope of the present invention. In Comparative Examples 2 to 5, the temperatures of the warm air 11 ejected from the warm air ejection slit port 5a in the tenter 5 were all outside the scope of the present invention.

Moreover, in the comparative example 6, using the dope composition 1 of the said Example 1, in order to produce the cellulose triacetate film of 80 micrometers in thickness, it carried out similarly to the case of the said Example 1, As a result, in the tenter 5 When the web 10 was stretched at an elongation of 65%, the web 10 broke, and a film could not be produced.

To the following Table 1, the kind of dope composition used for manufacture of the cellulose triacetate film in Examples 2-15, and Comparative Examples 1-6, the elongation (%) of the web 10, an extending process Just before entering the temperature (° C) of the warm air 11 to eject from the warm air jet slit 5a in the tenter 5, the glass transition temperature (Tg) (° C) of the cellulose triacetate film, and the tenter 5 The amount of residual solvent added (%) and the film thickness (µm) of the web 10 were all described.

And about the cellulose triacetate films obtained in Examples 2-15 and Comparative Examples 1-5, the haze value of a film was measured similarly to the case of said Example 1, and the result obtained is shown in following Table 1 All showed up.

<Example 16>

Using the following dope composition 2, it carried out substantially similarly to the case of Example 1, and manufactured the cellulose acetate propionate film.

(Dope composition 2)

100 parts by mass of cellulose acetate propionate

(Acetyl group substitution degree + propionyl group substitution degree = 2.45,

Mn = 60000, Mw = 180000, Mw / Mn = 3.00)

8 parts by mass of triphenylphosphate

2 parts by mass of ethyl phthalyl ethyl glycolate

Methylene chloride 360 parts by mass

60 parts by mass of ethanol

Tinuvin 109 (product of Ciba specialty chemicals company) 0.5 mass part

Tinuvin 171 (product of Ciba specialty chemicals company) 0.5 mass part

0.2 parts by mass of aerosil 972V (made by Nippon Aerosil Kabuki Kaisha)

In this Example 16, the amount of residual solvent of the web 10 just before entering the tenter 5 of an extending process was 12 mass%, and the elongation of the web 10 in the tenter 5 was 25%. . In addition, the temperature of the warm air 11 sprayed from the warm air blow slit port 5a in the tenter 5 was set to 185 degreeC, respectively.

Here, the temperature of the warm air 11 in the tenter 5 was Tg + 40 degreeC with respect to the glass transition temperature of the cellulose acetate propionate film after winding: Tg = 145 degreeC. The film thickness of the cellulose acetate propionate film after winding was 40 micrometers.

<Example 17-26>

As in the case of Example 16, cellulose acetate propionate was produced using dope composition 2, but in each of the examples, some of the film forming conditions were different as follows.

First, in Example 17 and Example 18, although the conditions were substantially the same as that of Example 16, the elongation of the web 10 in the tenter 5 of an extending process changes to 35 (%) and 40 (%). I was.

In Example 19, although it was set as substantially the same conditions as Example 16, the elongation rate of the web 10 in the tenter 5 of an extending process is changed to 60 (%), and the warm air in the tenter 5 is changed. The temperature of the warm air 11 sprayed from the blowing slit 5a was changed to 180 degreeC.

In Example 20, although the conditions were substantially the same as the case of Example 18, the temperature of the warm air 11 sprayed from the warm air blowing slit 5a in the tenter 5 was changed to 200 degreeC.

In Examples 21 to 23, the same conditions as in Example 17 were set, but the amount of residual solvent added to the web 10 immediately before entering the tenter 5 was 10 (%), 20 (%), and 35. (%) Respectively.

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

<Comparative Example 7 to Comparative Example 9>

For comparison, a cellulose acetate propionate film was produced using the dope composition 2 of Example 16, but differs from the case of Example 16 in the warm air blowing slit 5a in the tenter 5a. The temperature of the warm air 11 blown out from ()) was made into the thing of the range of this invention all.

To the following Table 1, the kind of dope composition used for manufacture of the cellulose acetate propionate film in Examples 16-26 and Comparative Examples 7-9, the elongation (%) of the web 10, At the temperature (° C) of the warm air 11 sprayed from the warm air jet slit port 5a in the tenter 5, the glass transition temperature (Tg) (° C) of the cellulose acetate propionate film after winding, and the tenter 5 The amount of residual solvent added (%) and the film thickness (µm) of the film was described.

And about the cellulose acetate propionate film obtained in Examples 16-26 and Comparative Examples 7-9, the haze value of a film was measured similarly to the case of said Example 1, and the result obtained is shown in the following table All were shown in 1.

Comparative Example 10

For comparison, a cellulose acetate propionate film was prepared in the same manner as in Example 1 using the following dope composition 3.

(Dope composition 3)

100 parts by mass of cellulose triacetate

(Mn = 148000, Mw = 310000, Mw / Mn = 2.1)

Methylene chloride 440 parts by mass

40 parts by mass of ethanol

0.2 parts by mass of aerosil 972V (made by Nippon Aerosil Kabuki Kaisha)

Here, the amount of residual solvent of the web (film) 10 just before entering the tenter 5 of an extending process was 12 mass%.

And the elongation of the web in the tenter 5 was made into 30%, and the temperature of the warm air 11 which blows off from the warm air blowing slit opening 5a in the tenter 5 was 180 degreeC. Here, the temperature of the warm air 11 in the tenter 5 was Tg + 70 degreeC with respect to the glass transition temperature of the cellulose triacetate film after winding up: Tg = 110 degreeC.

Since the plasticizer is not contained in the dope composition 3 of this comparative example 10, it broke at the time point where the web 10 was extended | stretched by elongation 10% or more in the tenter 5, and the film could not be produced.

As apparent from the results of Table 1 above, according to the cellulose ester films of Examples 1 to 26 of the present invention, in the method for producing a cellulose ester film by the solution casting film forming method, even if so-called high stretching, The haze does not increase, the optical property excellent in transparency and planarity, a cellulose ester film can be manufactured, and the production speed can be raised, the productivity of a film can be improved, and also the recent protective films for polarizing plates, etc. It could meet the demand of thinning, widening, and high quality.

On the other hand, in the cellulose ester films obtained by Comparative Examples 1 to 5 and Comparative Examples 7 to 9, when high stretching, the haze of the film was increased, and transparency and planarity were lowered. For this reason, the production rate of a cellulose ester film cannot be raised, and productivity of a film cannot be improved, and it was not able to comply with the requirements of thinning, widening, and high quality of protective films for polarizing plates.

Example 27

(Production of Polarizing Film)

In order to manufacture the liquid crystal display panel shown in FIG. 2, the polarizing film was produced first. That is, the polyvinyl alcohol film of 120 micrometers in thickness was uniaxially stretched by the temperature of 110 degreeC, and draw ratio 5 times. It was immersed for 60 seconds in the aqueous solution which consists of 0.075g of iodine, 5g of potassium iodide, and 100g of water, and then immersed in the 68 degreeC aqueous solution which consists of 6g of potassium iodide, 7.5g of boric acid, and 100g of water. This was washed with water and dried to obtain a polarizing film.

(Production of polarizing plate)

Subsequently, according to the following process 1-process 5, the cellulose triacetate film (T-1) of the film thickness of 80 micrometers produced in Example 6, and the film thickness 40 produced in Example 21 to said polarizing film The cellulose acetate propionate film (T-2) of μm was bonded to produce a polarizing plate 1. Process 1: The film of T-1 and T-2 which immersed in the 50 degreeC 2 mol / L sodium hydroxide solution for 60 second, and then washed with water and dried and saponified the side which joins to a polarizing film was obtained.

Process 2: The polarizing film was immersed for 1-2 second in the polyvinyl alcohol adhesive bath of 2 mass% of solid content.

Process 3: The excess adhesive agent adhered to the polarizing film in the process 2 was lightly wiped off, and the film of T-1 and T-2 processed by the process 1 was laminated | stacked and arrange | positioned at both sides of this polarizing film.

Process 4: The pressure of 20-30 N / cm <2> and conveyance speed were bonded the polarizing film arrange | positioned at process 3 and the film of T-1, T-2 at about 2 m / min.

Process 5: The polarizing film produced by the process 4 and the film of T-1, T-2 were dried for 2 minutes in 80 degreeC dryer, and the polarizing plate 1 was produced.

Next, as the polarizing plate 2 to be bonded to the other side of the liquid crystal display panel, using the polarizing plate 1 produced in the same manner as described above, the bonding direction was arranged so as to be symmetrical around the liquid crystal.

Therefore, as shown in Table 2, the film T-3 of the polarizing plate 2 turns into the cellulose acetate propionate film with a film thickness of 40 micrometers produced in Example 21, and the film T-4 of the polarizing plate 2 is And the cellulose triacetate film of the film thickness of 80 micrometers produced in Example 6 was obtained.

(Production of liquid crystal display panel)

Subsequently, the polarizing plates of both surfaces of a commercially available liquid crystal display panel (NEC color liquid crystal display, MultiSync, LCD1525J: product name, LA-1529HM) were carefully peeled off, respectively, and the produced polarizing plate 1 and the polarizing plate ( 2) was bonded together and the liquid crystal display panel was produced.

At this time, as shown in FIG. 2, the cellulose triacetate film (T-1) of the film thickness of 80 micrometers produced in Example 6 of the polarizing plate 1 and the polarizing plate 2 with respect to the liquid crystal of a center, and (T- 4) were bonded to the outside, respectively, and it bonded together so that the cellulose acetate propionate film (T-2) and (T-3) of the film thickness of 40 micrometers produced in Example 21 may be set to the liquid crystal side of the center, respectively.

In this case, the outer film (T-1) side of the polarizing plate 1 is the display side of the liquid crystal display panel, and the outer film (T-4) side of the polarizing plate 2 is the backlight side.

The contrast was measured about the liquid crystal display panel of Example 27 obtained in this way, and the obtained result is shown in following Table 2.

(Measurement of contrast at the time of display panel mounting)

The measurement of contrast at the time of display panel mounting was performed by evaluating the viewing angle of a display panel. Here, viewing angle evaluation measured the viewing angle using the liquid crystal display panel EZ-contrast by ELDIM. The measuring method ranked the contrast about the inclination angle of 80 degrees from the normal line direction with respect to a panel surface with respect to the white display of a liquid crystal display panel, and the contrast at the time of black display within the range of the following value in all directions. .

◎◎◎: Contrast over 40 degrees

◎◎: Contrast over 30 degrees in all directions

◎: Contrast over 20 degrees in all directions

○: Contrast over 15 degrees

(Triangle | delta): An area | region with contrast of more than 5 omni and less than 15 existed.

X: Contrast was less than 5 omnidirectional

<Example 28-31>

A liquid crystal display panel was fabricated in the same manner as in the twenty-ninth embodiment, but differs from that in the twenty-seventh embodiment as follows.

In Example 28, a 80-micrometer-thick cellulose triacetate film (T-1) produced in Example 6 and a 60-micrometer-thick cellulose acetate propionate film (T) produced in the polarizing film -2) is bonded and the polarizing plate 1 is produced, and as the polarizing plate 2 bonded to the other side of the liquid crystal display panel, using the polarizing plate 1 produced similarly to the case mentioned above, the bonding direction is It arranged so that it might become symmetric about the liquid crystal.

Therefore, as shown in Table 3, the film T-3 of the polarizing plate 2 turns into the cellulose acetate propionate film of 60 micrometers of film thickness produced in Example 25, and the film T-4 of the polarizing plate 2 is And the cellulose triacetate film of the film thickness of 80 micrometers produced in Example 6 was obtained.

In Example 29, a cellulose triacetate film (T-1) having a thickness of 80 µm prepared in Example 6 and a cellulose acetate propionate film having a thickness of 80 µm prepared in Example 26 (T) on a polarizing film -2) is bonded and the polarizing plate 1 is produced, and as the polarizing plate 2 bonded to the other side of the liquid crystal display panel, using the polarizing plate 1 produced similarly to the case mentioned above, the bonding direction is It arranged so that it might become symmetric about the liquid crystal.

Therefore, as shown in Table 2, the film T-3 of the polarizing plate 2 turns into the cellulose acetate propionate film with a film thickness of 80 micrometers produced in Example 26, and the film T-4 of the polarizing plate 2 is And the cellulose triacetate film of the film thickness of 80 micrometers produced in Example 6 was obtained.

In Example 30, the cellulose triacetate film (T-1) of the film thickness of 80 micrometers produced in Example 13, and the cellulose acetate propionate film of the film thickness of 60 micrometers produced in Example 25 were used for the polarizing film (T -2) is bonded and the polarizing plate 1 is produced, and as the polarizing plate 2 bonded to the other side of the liquid crystal display panel, using the polarizing plate 1 produced similarly to the case mentioned above, the bonding direction is It arranged so that it might become symmetric about the liquid crystal.

Therefore, as shown in Table 2, the film T-3 of the polarizing plate 2 turns into the cellulose acetate propionate film with a film thickness of 60 micrometers produced in Example 25, and the film T-4 of the polarizing plate 2 is And the cellulose triacetate film of the film thickness of 80 micrometers produced in Example 13 was obtained.

In Example 31, the cellulose triacetate film (T-1) of the film thickness of 80 micrometers produced in Example 13, and the cellulose acetate propionate film of 40 micrometers produced in Example 17 were used for the polarizing film (T -2) is bonded and the polarizing plate 1 is produced, and as the polarizing plate 2 bonded to the other side of the liquid crystal display panel, using the polarizing plate 1 produced similarly to the case mentioned above, the bonding direction is It arranged so that it might become symmetric about the liquid crystal.

Therefore, as shown in Table 2, the film T-3 of the polarizing plate 2 turns into the cellulose acetate propionate film with a film thickness of 40 micrometers produced in Example 17, and the film T-4 of the polarizing plate 2 is And the cellulose triacetate film of the film thickness of 80 micrometers produced in Example 13 was obtained.

Thus, about the liquid crystal display panels of Example 28-31 obtained, the contrast was measured similarly to the case of Example 27, and all the obtained Table 2 was shown below.

Comparative Example 11

For comparison, a liquid crystal display panel was produced in the same manner as in the case of Example 27, but the difference from the case of Example 27 was a cellulose triacetate film having a thickness of 80 μm produced in Comparative Example 2 on the polarizing film ( T-1) and the cellulose acetate propionate film (T-2) of 80-micrometer-thick film produced in the comparative example 8, the polarizing plate 1 is produced, and the polarizing plate bonded to the other side of a liquid crystal display panel. As (2), using the polarizing plate 1 produced as mentioned above, it arrange | positioned so that the bonding direction might become symmetric centering on a liquid crystal.

Therefore, as shown in Table 2, the film T-3 of the polarizing plate 2 turns into a cellulose acetate propionate film with a film thickness of 80 µm produced in Comparative Example 8, and the film T-4 of the polarizing plate 2 And the cellulose triacetate film of the film thickness of 80 micrometers produced by the comparative example 2 was obtained.

About the liquid crystal display panel of the comparative example 11 obtained in this way, contrast was measured similarly to the case of Example 27, and all the obtained results were shown in following Table 2.

As is apparent from the results of Table 2 above, it can be seen that according to the liquid crystal display panels of Examples 27 to 31 of the present invention, the liquid crystal display panels of Comparative Example 11 had excellent contrast.

Claims (9)

The resin solution containing a cellulose ester resin is cast | flow_spreaded to a flexible support body, a flexible film is formed, the solvent in a flexible film is dried until it becomes a state which can be peeled off, and it peels from a flexible support body, and then peeled the web It is a manufacturing method of the cellulose ester film which obtains a cellulose-ester film by drying and winding up a solvent through the extending process which grasps both ends of and extends to the width direction, The elongation rate 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 from Tg + 35 ° C. to the glass transition temperature (Tg) of the film after the winding. It is Tg + 80 degreeC, The manufacturing method of the cellulose-ester film characterized by the above-mentioned. The method for producing a cellulose ester film according to claim 1, wherein the amount of residual solvent in the film immediately before entering the stretching step is 10 to 35% by mass. The manufacturing method of the cellulose-ester film of Claim 1 or 2 which has a removal means which removes organic components other than the solvent contained in the exhaust wind sent from the extending process. The 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 from the stretching step. The manufacturing method of the cellulose-ester film of Claim 4 with which the said removal means is connected in multiple numbers. It is a cellulose ester film manufactured by the method of any one of Claims 1-3, The width of the film after winding is 1650-2500 mm, The cellulose ester film characterized by the above-mentioned. The film thickness of the film after winding is 40-80 micrometers, The cellulose-ester film of Claim 6 characterized by the above-mentioned. The cellulose ester film of Claim 6 or 7 is used for one surface, The polarizing plate characterized by the above-mentioned. The cellulose ester film of Claim 6 or 7 is used, The display apparatus characterized by the above-mentioned.

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