CN101610892B - 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 DEG C. Preferably, the amount of a solvent remaining in the film immediately before the stretching step is 10 to 35 mass%.

Description

Cellulose ester membrane, its manufacture method, the polarizer that has used cellulose ester membrane and display unit

Technical field

The present invention relates to cellulose ester membrane, its manufacture method, the polarizer that has used cellulose ester membrane and the display unit that can be used for the protective film for polarizing plate of liquid crystal indicator (LCD), phase retardation film, the angle of visual field and enlarge film, be used for the utilizations such as various functional membranes such as antireflection film of plasma scope.

Background technology

In recent years, liquid crystal indicator is because its picture quality improves, high-precision refinement technology improves, and be applied to television set, large-scale monitor aspect, particularly expect the maximization of these liquid crystal indicators and by effectively producing to reduce cost etc., these material aspects that are desirably in liquid crystal indicator are also increasingly strong, the wide cut of seeking blooming.

In addition, in recent years along with the sharp increase of liquid crystal TV, correspondingly also sharp increase of the demand of blooming, its productive raising of strong request.Aspect the cellulose ester membrane that adopts the solution casting method masking, adopt film, need a small amount of dry solvent amount to get final product, therefore improving speed of production becomes possibility.

By expanding the curtain coating width on the casting support of being made by rotary actuation stainless steel endless belt or the stainless steel rotary drum of rotary actuation etc., adopt solution casting masking method can obtain wide film.

On the other hand, there is the upper limit in the width of casting support, casting head because of the restriction of device manufacture view.Casting support is in the situation of endless belt, and the upper limit of width is 2000mm at present.In this case, the sinuous movement (crawling) when considering the endless belt conveying etc., it is safe that the upper limit of curtain coating width is to the maximum about 1900mm.In addition, casting support is in the situation of the rotary drum made of metal, the same because restriction on making, and Breadth Maximum is about 2500mm.In the situation that the rotary drum masking, the gelation that cooling causes is so that casting films has self-supporting, thereby, be necessary to be filmed in the part that is cooled, but there is variations in temperature in the end because of heat release, can't use, the curtain coating width terminates in about 2000mm.

Width when any method all makes curtain coating because of the restriction in the device fabrication is restricted, and present case is to consider that the film of delaying by convection current stretches, and obtains wide film width as far as possible, obtains the film of wide cut.The film of delaying as convection current stretches to obtain the method for the film of wide cut, known being used in PET, the polyvinyl alcohol etc., with respect to about 2～4 times films that obtain wide cut of curtain coating width tension.

Yet, in the situation that cellulose ester membrane because molecular structure is rigidity, is thought to increase extensibility so far.In following patent documentation 1,2, proposed cellulose ester membrane is stretched to 1.2 times.

Record in the patent documentation 1: be more than 115 ℃ and below 160 ℃ the time in the residual solvent amount less than 120 quality %, temperature, be stretched to 1.2～4.0 times.In addition, record in the patent documentation 2: being more than 0 ℃ and in the thermostat below 4 ℃ in the temperature difference of film by section, is below room temperature～160 ℃ the time in temperature, is stretched to more than 1.2 times and below 1.8 times.

Patent documentation 1: JP 2002-71957 communique

Patent documentation 2: JP 2002-131540 communique

Summary of the invention

Invent problem to be solved

Yet, adopting patent documentation 1,2 manufacture methods of putting down in writing, the problem of existence is: the mist degree of cellulose esters uprises, the optical transmission rate reduces, and when therefore being assembled in the display unit, contrast reduces.And can think, the existence of this problem is because film has been applied unnecessary power when stretching.

The objective of the invention is to solve above-mentioned the problems of the prior art, even provide in the stretching process of sheet stock sheet stock is stretched to the manufacture method of the cellulose ester membrane that mist degree also can not uprise more than 1.2 times, cellulose ester membrane, the polarizer that has used cellulose ester membrane and the display unit of employing the method manufacturing at width.

The method of dealing with problems

To achieve these goals, the invention of claim 1 relates to a kind of manufacture method of cellulose ester membrane, the method comprises, the resin solution curtain coating that will comprise cellulose ester resin forms casting films at casting support, solvent in the casting films is carried out drying until casting films reaches strippable state, casting films is peeled off from casting support, then through controlling the both ends of the sheet stock that strips down and the stretching process that stretches at width, again solvent is carried out drying, thereby and film reeled obtain cellulose ester membrane, wherein, the extensibility of sheet stock is 20～60% in the stretching process, and with respect to the glass transition temperature (Tg) of the film after reeling, the temperature of the hot blast that blows out from the hot blasting device of stretching process is Tg+35 ℃～Tg+80 ℃.

The invention of claim 2 is in the manufacture method of the cellulose ester membrane of claim 1, and the residual solvent amount that is about to enter the film before the stretching process is 10～35 quality %.

The invention of claim 3 is in the manufacture method of the cellulose ester membrane of claim 1 or 2, has the device of removing, and the described device of removing is removed the organic principle that is included in beyond desolventizing from the exhaust wind that stretching process is sent here.

The invention of claim 4 is in the manufacture method of the cellulose ester membrane of claim 3, and the exhaust wind of having removed described organic principle is recycled as the some of the dry wind of stretching process upstream again.

The invention of claim 5 is in the manufacture method of the cellulose ester membrane of claim 4, and a plurality of described devices of removing are connected together.

The invention of claim 6 is to adopt the cellulose ester membrane that each method is made in the claim 1～3, and wherein, the width of the film behind the coiling is 1650～2500mm.

The invention of claim 7 is cellulose ester membranes of claim 6, and wherein, the thickness of the film behind the coiling is 40～80 μ m.

The invention of claim 8 is the polarizers that used the cellulose ester membrane of claim 6 or 7 in one side.

The invention of claim 9 is display unit of having used the cellulose ester membrane of claim 6 or 7.

The invention effect

The invention of claim 1 is in the manufacture method of following cellulose ester membrane, the extensibility of sheet stock is 20～60% in the stretching process, and the temperature of the hot blast that blows out from the hot blasting device of stretching process is Tg+35 ℃～Tg+80 ℃ with respect to the glass transition temperature (Tg) of the film after reeling; The manufacture method of described cellulose ester membrane comprises, the resin solution curtain coating that will comprise cellulose ester resin forms casting films at casting support, solvent in the casting films is carried out drying until casting films reaches strippable state, casting films is peeled off from casting support, then through controlling the both ends of the sheet stock that strips down and the stretching process that stretches at width, again solvent is carried out drying, thereby and film reeled obtain cellulose ester membrane.Therefore, invention is according to claim 1 carried out height stretching even can realize making, and the mist degree of film can not uprise yet, and has the effect of the cellulose ester membrane of the good optical characteristics of the transparency, flatness.

The invention of claim 2 is in the manufacture method of the cellulose ester membrane of claim 1, and the residual solvent amount that is about to enter the film before the stretching process is 10～35 quality %.Therefore, invention according to claim 2 can when further reducing to put on the stress of film, be guaranteed the self-supporting of appropriateness.

Improve as described herein the temperature of stretching process, then have the tendency of the volatile quantity increase of the organic principles such as plasticizer.Yet invention according to claim 3 owing to having and remove the device that is included in from the organic principle in the exhaust wind of stretching process, can prevent that organic principle is to the pollution of film with to the pollution of film manufacturing device.In addition, according to claim 4, the part as the dry wind of stretching process upstream is recycled again, therefore can reach the effect of the manufacturing cost that reduces cellulose ester membrane.

The invention of claim 5 is in the manufacture method of the cellulose ester membrane of claim 4, and a plurality of described devices of removing link to each other.Therefore, invention according to claim 5 can positively reduce the concentration of the organic principle in the exhaust wind, so exhaust wind can be recycled effectively as the part of the dry wind of stretching process upstream again.

The invention of claim 6 is to adopt the cellulose ester membrane that each method is made in the claim 1～3, and wherein, the width of the film behind the coiling is 1650～2500mm.Therefore, invention according to claim 6 can realize making the effect that the large liquid crystal indicator of width is used cellulose ester membrane.

In the cellulose ester membrane invention of claim 7, the thickness of the film behind the coiling is 40～80 μ m.Therefore, invention according to claim 7, the effect of realization is can the slimming of display unit be contributed.

According to claim 8, polarizer invention when being assembled in it on liquid crystal indicator, can not cause that contrast reduces, and the effect of realization is visual good.

According to claim 9, display unit invention, the effect of realization are to cause that contrast reduces, visual good.

Description of drawings

The flow chart of the object lesson of the device of the manufacture method of [Fig. 1] demonstration enforcement cellulose ester membrane of the present invention.

[Fig. 2] shows the amplification sectional view of the object lesson of the LCD panel that has used the cellulose ester membrane that adopts method manufacturing of the present invention.

Symbol description

1: endless belt (casting support)

2: casting head

3: stripper roll

5: tenter frame (stretching process)

5a: hot blast blows out slit mouth (hot blasting device)

5b: exhaust wind outlet

6: the roller transport drying device

7: conveying roller

8: up-coiler

10: sheet stock

11: hot blast (dry wind)

12: exhaust wind

13a: organic principle is removed device (organic principle is removed equipment)

13b: organic principle is removed device (organic principle is removed equipment)

14: exhaust wind

15: dry wind

16: exhaust wind

20: cellulose ester membrane

The specific embodiment of invention

Below, embodiments of the present invention are described, but the present invention is not limited.

The manufacture method of cellulose ester membrane of the present invention adopts solution casting masking method to carry out, the method comprises, resin solution (rubber cement) curtain coating that will comprise cellulose ester resin forms casting films at the casting support of being made by rotary actuation stainless steel endless belt or rotary drum etc., solvent in the casting films is carried out drying until casting films reaches strippable state, casting films is peeled off from casting support, then through controlling the both ends of the sheet stock that strips down and the stretching process that stretches at width, dry solvent, and film reeled to obtain cellulose ester membrane, it is characterized in that, the extensibility of sheet stock is 20～60% in the stretching process, and for the glass transition temperature (Tg) of the film after reeling, the temperature of the hot blast that blows out from the hot blasting device in the stretching process is Tg+35 ℃～Tg+80 ℃.

Stretching process in the present embodiment adopts the tenter frame mode, and the dual-side edge of namely controlling sheet stock (or film) with clip etc. stretches, and the hot blasting device is that the hot blast of tenter frame blows out the slit mouth.

In the present embodiment, the resin solution (rubber cement) that comprises cellulose ester resin contains plasticizer, postpones material more than at least a kind and cellulose ester resin and solvent in adjusting agent, ultra-violet absorber, particulate and the small molecular weight material.

Below, be described in detail.

Cellulose esters is the cellulose esters that the hydroxyl in cellulose source is replaced by acyl group etc.Can list such as cellulose acylates such as, cellulose ethanoate, cellulosic triacetate, cellulose ethanoate propionic ester, cellulose acetate butyrate, cellulose ethanoate propionic ester butyrates, have the cellulose ethanoate of aliphatic polyester graft side chain etc.Wherein, preferred cellulose acetic acid esters, cellulose ethanoate propionic ester, have the cellulose ethanoate of aliphatic polyester graft side chain.As long as in the scope that does not affect effect of the present invention, also can contain other substituting group.

As the example of cellulosic triacetate, the substitution value of preferred acetyl group is more than 2.0 below 3.0.By making substitution value in this scope, can obtain good formability, and can obtain direction delay (Ro) and thickness direction retardation (Rt) in the desired face.If the substitution value of acetyl group is lower than this scope, then sometimes the humidity resistance of phase retardation film, the especially poor dimensional stability under wet heat condition if substitution value is excessive, then can't show necessary lag characteristic sometimes.

Raw cellulose as the cellulose esters that uses among the present invention is not particularly limited, and can enumerate velveteen, timber slurry, mestha etc.In addition, the cellulose esters that is obtained by these raw celluloses can mix use with arbitrary proportion separately.

In the present invention, several mean molecule quantities of preferred cellulose ester are 60000～300000 scope, and the mechanical strength of gained film is strong like this.More preferably 70000～200000.

In this manual, will be called good solvent to the organic solvent that cellulose ester membrane has a good solubility, in addition, performance Main Function during with dissolving, a large amount of solvents that use are called main solvent or primary solvent therein.

Example as good solvent, can list acetone, MEK, cyclopentanone, the ketones such as cyclohexanone, oxolane (THF), 1, the 4-diox, 1,3-dioxa penta ring, 1, the ethers such as 2-dimethoxy-ethane, methyl formate, Ethyl formate, methyl acetate, ethyl acetate, pentyl acetate, the ester classes such as gamma-butyrolacton, and methyl cellosolve, dimethyl-imidazolinone, dimethyl formamide, dimethylacetylamide, acetonitrile, dimethyl sulfoxide (DMSO), sulfolane, nitroethane, carrene, methyl acetoacetate etc., preferred 1,3-dioxa penta ring, THF, MEK, acetone, methyl acetate and carrene.

Except above-mentioned organic solvent, also contain the alcohol of 1～40 quality % carbon number 1～4 in the preferred rubber cement.These alcohol can be used as the gelation solvent and use: behind curtain coating rubber cement on the casting support, the solvent start vaporizer, the ratio of alcohol increases, so make sheet stock (will in curtain coating on the casting support rubber cement film behind the cellulose derivative rubber cement be called sheet stock) gelation, sheet stock is toughened up, be easy to peel off from casting support, when these pure ratios are few, also can play the effect that promotes that non-chlorine class organic solvent dissolves cellulose ester resin.

As the alcohol of carbon number 1～4, can enumerate methyl alcohol, ethanol, normal propyl alcohol, isopropyl alcohol, n-butanol, sec-butyl alcohol, the tert-butyl alcohol, propylene glycol monomethyl ether.Wherein, from the rubber cement good stability, boiling point is lower, drying property good and preferred alcohol is considered in the aspect such as avirulence.These organic solvents use does not separately have a dissolubility to cellulose derivative, is called poor solvent.

As satisfying this condition, can dissolving with high concentration the solvent of preferred macromolecular compound cellulose ester resin, most preferred solvent is carrene: the ratio of ethanol is 95: 5～80: 20 mixed solvent.Perhaps, also can preferably use methyl acetate: 60: 40～95: 5 mixed solvent of ethanol.

Can mix following various additive in the film of the present invention: the plasticizer of giving film processability, flexibility, moisture resistance, give the particulate (delustering agent) of film smoothness, give the ultra-violet absorber of ultraviolet radiation absorption function, prevent antioxidant that film is deteriorated etc.

As the plasticizer that uses among the present invention, for fear of making film produce mist degree, ooze out or volatilize from film, preferably have following functional group: this functional group can interact by the condensation polymer with the reactive metal compound of cellulose ester resin or hydrolyzable polycondensation such as hydrogen bond.

As such functional group; can list hydroxyl, ether, carbonyl, ester group, carboxylic acid residues, amino, imino group, amide groups, imide, cyano group, nitro, sulfonyl, sulfonic acid moieties, phosphono, phosphonic acids residue etc., preferred carbonyl, ester group, phosphono.

Example as these plasticizer, can preferably use phosphate plasticizer, phthalic ester plasticizer, trimellitic acid ester plasticizer, PMA class plasticizer, polyalcohol ester plasticizer, glycolic ester plasticizer, citric acid ester plasticizer, fatty acid ester plasticiser, carboxylic acid esters plasticizer, polyesters plasticizer etc., particularly preferably the non-phosphate plasticizers such as polyalcohol ester plasticizer, glycolic salt plasticizer, polybasic carboxylic acid ester plasticizer.

Polyol ester is formed by the ester of the aliphatic polyol more than 2 yuan and monocarboxylic acid, has aromatic rings or cycloalkyl ring in the preferred molecule.This polyalcohol represents with following general formula (1).

General formula (1) R1-(OH) _n

(in the formula, R1 represents that n valency organic group, n represent the positive integer more than 2)

As the example of preferred polyalcohol, can enumerate for example following compound, but the present invention is not limited to these compounds.

Example as preferred polyalcohol, can enumerate, ribitol, arabite, ethylene glycol, diglycol, triethylene-glycol, tetraethylene-glycol, 1, the 2-propane diols, 1, ammediol, dipropylene glycol, tripropylene glycol, 1, the 2-butanediol, 1, the 3-butanediol, 1, the 4-butanediol, one contracting dibutylene glycol, BT, 1, the 5-pentanediol, 1, the 6-hexylene glycol, hexanetriol, galactitol, mannitol, 3-methylpentane-1,3, the 5-triol, pinacol, sorbierite, trimethylolpropane, trimethylolethane, xylitol etc.Particularly preferably triethylene-glycol, tetraethylene-glycol, dipropylene glycol, tripropylene glycol, sorbierite, trimethylolpropane, xylitol.

Monocarboxylic acid as can be used for polyol ester is not particularly limited, and can use known aliphatic monocarboxylic acid, alicyclic monocarboxylic acid, aromatic monocarboxylate etc.When using alicyclic monocarboxylic acid, aromatic monocarboxylate, can improve poisture-penetrability, retention, therefore preferred.

As the example of preferred monocarboxylic acid, can enumerate for example following compound, but the present invention is not limited to these compounds.

As aliphatic monocarboxylic acid, can preferably use the straight chain of carbon number 1～32 or have the aliphatic acid of side chain.More preferably carbon number is 1～20, particularly preferably 1～10.Can increase the compatibility with cellulose ester resin when containing acetic acid, therefore preferred, also preferred acetic acid mixes use with other monocarboxylic acid.

Example as preferred aliphatic monocarboxylic acid, can enumerate, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, sad, n-nonanoic acid, capric acid, 2-ethyl-caproic acid, hendecanoic acid, dodecylic acid, tridecanoic acid, tetradecanoic acid, pentadecanoic acid, hexadecanoic acid, Heptadecanoic acide, octadecanoid acid, nonadecylic acid, arachic acid, behenic acid, lignoceric acid, hexacosoic acid, carboceric acid, montanic acid, melissic acid, the saturated fatty acids such as lacceroic acid, undecenoic acid, oleic acid, sorbic acid, linoleic acid, leukotrienes, the unrighted acids such as eicosatetraenoic acid etc.

As the example of preferred alicyclic monocarboxylic acid, can enumerate cyclopentane-carboxylic acid, cyclohexane-carboxylic acid, cyclooctane carboxylic acid, or derivatives thereof.

Example as preferred aromatic monocarboxylate, can enumerate, benzoic acid, toluic acid etc. have imported the benzoic acid derivative of alkyl at benzoic phenyl ring, can enumerate, biphenyl carboxylic acids, naphthalene-carboxylic acid, tetralin carboxylic acid etc. have aromatic monocarboxylate, the or derivatives thereof of 2 above phenyl ring, particularly preferably benzoic acid.

The molecular weight of polyol ester is not particularly limited, and is preferred 300～1500, and more preferably 350～750.Because molecular weight is more large more not volatile, so the large polyol ester of preferred molecular weight, and consider the polyol ester that preferred molecular weight is little from poisture-penetrability, with the compatibility aspect of cellulose ester resin.

About being used for the carboxylic acid of polyol ester, can use separately a kind, also can use mixing more than 2 kinds.In addition, all esterifications of OH base in the polyalcohol also can reserve part OH base.

The glycolic ester plasticizer is not particularly limited, and can preferably use the glycolic ester plasticizer that has aromatic rings or cycloalkyl ring in the molecule.As preferred glycolic ester plasticizer, can example such as butyl phthalyl butyl glycolate, ethyl methyl phthallyl ethyl glycollate, methyl methyl phthallyl ethyl glycollate etc.

In phosphate plasticizer, can use triphenyl phosphate, tricresyl phosphate, tricresyl phosphate base diphenyl, octyl diphenyl phosphate, di(2-ethylhexyl)phosphate phenyl Biphenyl Ester, trioctyl phosphate, tributyl phosphate etc., in phthalic ester plasticizer, can use diethyl phthalate, DMEP, repefral, dioctyl phthalate, dibutyl phthalate, phthalic acid two (2-Octyl Nitrite), dicyclohexyl phthalate etc.

These plasticizer can be used alone or two or more kinds mixed.

The consumption of preferred plasticizer is 1～20 quality %.More preferably 6～16 quality % are particularly preferably 8～13 quality %.

Add the particulates such as delustering agent in the preferred cellulose ester resin of the present invention, to give its smoothness.As particulate, can list the particulate of inorganic compound or the particulate of organic compound.

Example as the particulate of inorganic compound can list the particulates such as silica, titanium dioxide, aluminium oxide, zirconia, tin oxide.Wherein, preferably contain the particulate of the compound of silicon atom, especially preferred silicon dioxide microparticle.As silicon dioxide microparticle, can enumerate AEROSIL 200, the 200V, 300, R972, R972V, R974, R202, R812, R805, OX50, the TT600 etc. that make such as AEROSIL Co., Ltd..

As the example of the particulate of organic compound, can list the particulate of acrylic resin, organic siliconresin, fluorine compounds resin, carbamate resins etc.

The primary particle size of particulate is not particularly limited, and the average grain diameter in the preferably telolemma is about 0.05～5.0 μ m.More preferably 0.1～1.0 μ m.

When the average grain diameter of particulate refers to electron microscope or observation by light microscope cellulose ester membrane, the mean value of particle long axis direction length in the film viewing area.Particle in the film of observing can be primary particle, also can be the offspring that primary particle is aggregated into, and that usually observes mostly is offspring.

The dispersion of particulate preferably will be mixed with the composition of particulate and solvent and process with the high pressure dispersal device.The high pressure dispersal device is that the composition that is mixed with particulate and solvent is passed through in the tubule high speed, reaches thus the device of the specific conditions such as high shear and high pressure conditions.

As above-mentioned high pressure dispersal device, can list the super-pressure homogenizer (trade name Microfluidizer) of Microfluidics Corporation company system for example or the Nanomizer that Nanomizer company makes, and Manton-Gaulin type high pressure dispersal device, the Homogenizer that makes such as Izumifood Machinery etc.

In the present invention, after microparticulate is in the lower alcohols solvent that contains 25～100 quality %, and cellulose ester resin is dissolved in the rubber cement of making in the solvent and mixes mutually.

Here, the ratio that contains of lower alcohol is preferably 50～100 quality %, 75～100 quality % more preferably.

In addition, as the example of lower alcohols, can preferably list methyl alcohol, ethanol, propyl alcohol, isopropyl alcohol, butanols etc.

Solvent as beyond the lower alcohol is not particularly limited, used solvent when preferably using the cellulose esters masking.

From preventing deteriorated angle consideration, contain ultra-violet absorber in the various bloomings such as preferred polaroid protective film, phase retardation film, optical compensation films.

As ultra-violet absorber, consider from preventing the polarizer, the deteriorated aspect of liquid crystal, preferably strong to the ultraviolet absorption ability below the wavelength 370nm, and from the consideration of liquid crystal expressivity aspect, the preferably goods few to the visible absorption more than the wavelength 400nm.

In the present embodiment, as spendable ultra-violet absorber, for example can enumerate, hydroxy benzophenone ketone compounds, benzotriazole compound, salicylate compounds, benzophenone compound, cyanoacrylate compound, nickel complex compounds etc., preferred painted few benzotriazole compound.In addition, also preferably use the ultra-violet absorber of Unexamined Patent 10-182621 communique, the record of Unexamined Patent 8-337574 communique, the polymeric UV absorber of Unexamined Patent 6-148430 communique record.

Object lesson as useful ultra-violet absorber, can enumerate, 2-(2 '-hydroxyl-5 '-aminomethyl phenyl) BTA, 2-(2 '-hydroxyl-3 ', 5 '-di-tert-butyl-phenyl) BTA, 2-(2 '-hydroxyl-3 '-tert-butyl group-5 '-aminomethyl phenyl) BTA, 2-(2 '-hydroxyl-3 ', 5 '-di-tert-butyl-phenyl)-the 5-chlorobenzotriazole, 2-(2 '-hydroxyl-3 '-(3 "; 4 " 5 "; 6 "-tetrahydro phthalimide-based methyl)-5 '-aminomethyl phenyl) BTA, 2, (4-(1 for the 2-methylene bis, 1,3, the 3-tetramethyl butyl)-6-(2H-BTA-2-yl) phenol, 2-(2 '-hydroxyl-3 '-tert-butyl group-5 '-aminomethyl phenyl)-the 5-chlorobenzotriazole, 2-(2H-BTA-2-yl)-6-(straight chain and side chain dodecyl)-4-methylphenol, the mixture of octyl group-3-(3-tertiary butyl-4-hydroxy-5-(chloro-2H-BTA-2-yl) phenyl) propionic ester and 2-ethylhexyl-3-(3-tertiary butyl-4-hydroxy-5-(5-chloro-2H-BTA-2-yl) phenyl) propionic ester etc., but be not limited to these compounds.

In addition, as the commercially available product of ultra-violet absorber, can preferably use TINUVIN 109, TINUVIN 171, TINUVIN 326 (making by Ciba Speciality Chemicals company).

In addition, object lesson as spendable ultra-violet absorber benzophenone compound among the present invention, can enumerate, 2,4-dihydroxy benaophenonel, 2,2 '-dihydroxy-4-methoxy benzophenone, 2-hydroxyl-4-methoxyl group-5-diphenylsulfone ketone, two (2-methoxyl group-4-hydroxyl-5-benzophenone methylmethane) etc., but be not limited to these compounds.

In the present invention, preferably the addition of these ultra-violet absorbers is 0.01～10 quality % scope, more preferably 0.1～5 quality % with respect to cellulose esters (cellulose derivative).If the consumption of ultra-violet absorber is very few, then the ultraviolet radiation absorption effect is insufficient sometimes, if the amount of ultra-violet absorber is too much, then the transparency of film occurs deteriorated, therefore not preferred sometimes.The goods that the ultra-violet absorber preferred thermal stability is high.

In addition, the ultra-violet absorber that can be used for the cellulose ester membrane of present embodiment also can be enumerated the polymeric UV absorber (or ultraviolet-absorbing polymer) of putting down in writing in Unexamined Patent 6-148430 communique and the JP 2002-47357 communique.Especially preferably use general formula (1) or the general formula (2) put down in writing in the Unexamined Patent 6-148430 communique, polymeric UV absorber shown in the general formula (3) of perhaps putting down in writing in the JP 2002-47357 communique, (6), (7).

Antioxidant is also referred to as deterioration preventing agent usually, the antioxidant that preferably contains in the cellulose ester membrane as blooming.That is to say, liquid crystal image display unit etc. is in the high humidity condition of high temperature lower time, sometimes occurs deteriorated as the cellulose ester membrane of blooming.Antioxidant can postpone to decompose such as the film that causes because of the phosphoric acid of the halogen in the residual solvent in the film, phosphoric acid class plasticizer etc., plays the effect of prevention, so contains antioxidant in the preferred film.

As such antioxidant, the preferred hindered phenol compound that uses, for example can enumerate, 2, the 6-BHT, (3-(3 for pentaerythrite-four, the 5-di-tert-butyl-hydroxy phenyl) propionic ester), triethylene glycol-two (3-(the 3-tert-butyl group-5-methyl-4-hydroxy phenyl) propionic ester), 1,6-hexylene glycol-two (3-(3,5-di-tert-butyl-hydroxy phenyl) propionic ester), two (positive hot sulfenyl)-6-(the 4-hydroxyls-3 of 2,4-, 5-di-tert-butyl amido)-1,3,5-triazine, (3-(3 for 2,2-sulphur connection-di ethylene bis, the 5-di-tert-butyl-hydroxy phenyl) propionic ester), octadecyl-3-(3, the 5-di-tert-butyl-hydroxy phenyl) propionic ester, N, N '-hexa-methylene two (3,5-di-t-butyl-4-hydroxyl-hydrocinnamamide), 1,3,5-trimethyl-2,4,6-three (3,5-di-t-butyl-4-hydroxy benzenes methyl) benzene, three (3,5-di-t-butyl-4-hydroxy benzenes methyl)-isocyanuric acid esters etc.Especially preferred 2,6-di-t-butyl-paracresol, pentaerythrite-four (3-(3,5-di-tert-butyl-hydroxy phenyl) propionic ester), triethylene glycol-two (3-(the 3-tert-butyl group-5-methyl-4-hydroxy phenyl) propionic ester).

In addition, also example capable of being combined such as N, the Phosphorus processing stabilizers such as hydrazine metalloid passivator, three (2,4-di-tert-butyl-phenyl) phosphite ester such as N '-two (3-(3,5-di-tert-butyl-hydroxy phenyl) propiono) hydrazine.

Below, the embodiment of the cellulose ester membrane that just the present invention relates to is elaborated.Film is by the preparation of solution casting film-forming method.

Fig. 1 is for show to implement adopting solution casting masking legal system to make the flow chart of object lesson of device of the method for cellulose ester membrane.But implement not to be subjected to when of the present invention the restriction of accompanying drawing shown below.

At first, in the unshowned in the drawings dissolution kettle, cellulose ester resin is dissolved in the mixed solvent of good solvent and poor solvent, adds subsequently above-mentioned plasticizer, ultra-violet absorber, preparation resin solution (rubber cement).

In Fig. 1, the rubber cement that will prepare in dissolution kettle is subsequently delivered to casting head (2) by for example compression type quantitative gear pump through conduit, begins the curtain coating rubber cement by the curtain coating position of casting head (2) on casting belt (1).Casting belt (1) is equivalent to casting support of the present invention, its endless belt for being made by stainless steel, and rotary actuation and circular flow.

During by casting head (2) curtain coating rubber cement, can adopt the roller of regulating the thickness of curtain coating rubber cement film (sheet stock) out with scraper plate to lick formula scraper plate method or the contrary roller rubbing method regulated with the contrary roller that rotates etc., preferably can regulate mouthful shape of slit of mould part, and easily make the pressing die head that adds of uniform film thickness.Add pressing die head and comprise rack type die (coat hanger die), T die head etc., can optional preferredly use.

Casting belt (1) is suspended between a pair of rotary drum, and the top in the middle of it transport section and the bottom section of transporting respectively by a plurality of rollers (diagram slightly) from medial support.

In the curled portion rotary drum of casting belt (1) two ends one or both are provided with the drive unit of giving casting belt (1) tension force, and thus, casting belt (1) uses under the stretched condition that has applied tension force.

In addition, in the present embodiment, be 1650～2500mm in order to ensure the width of coiling caudacoria, making the casting belt width is that the curtain coating width of 2000～2500mm, cellulose ester solution is 1900～2480mm.Like this, can make the wide liquid crystal indicator cellulose ester membrane of width by the casting support mode.

Here, as long as width, the curtain coating width of cellulose ester solution and the width of coiling caudacoria of casting support (1) are respectively more than the above-mentioned lower limit, can tackle the in recent years maximization of liquid crystal indicator.

In addition, following as long as the width of the curtain coating width of the width of casting belt (1), cellulose ester solution and coiling caudacoria is respectively higher limit, even peel off under the state that the residual solvent amount is many in the caudacoria, can not cause costal fold to fall yet or stretch inequality.

In addition, in the present embodiment, the peripheral speed of casting belt (1) is 80～200m/min.

That is to say, the peripheral speed by making casting belt (1) can improve the speed of production of film than the rotary drum peripheral speed was fast in the past, but the productivity of increased fiber cellulose ester film.

The temperature of casting belt during as masking (1), it can be 0 ℃ of conventional temperature range～the be lower than temperature of solvent boiling point, during for mixed solvent, can under temperature is lower than the boiling temperature of the minimum solvent of boiling point, carry out curtain coating, more preferably 5 ℃～than the scope of low 5 ℃ of solvent boiling point.

As mentioned above, be cast to the rubber cement on casting belt (1) surface by cooling gel, gel film strength (film-strength) increases, also can by until before peeling off during in the promotion drying increase gel film strength (film-strength).

In addition, in order to improve film speed, can with casting belt (1) casting head (2) that pressurizes more than 2 be set in curtain coating, distribute the rubber cement amount, carry out the multilayer masking.

On casting belt (1), in order to make sheet stock (10) dry solidification to the film-strength that can peel off by stripper roll (3) from casting belt (1), preferably being dried to the middle residual solvent amount of sheet stock (10) is below the 150 quality %, more preferably 80～120 quality %.The temperature of sheet stock is 0～30 ℃ when in addition, preferably peeling off sheet stock (10) from casting belt (1).In addition, after sheet stock (10) has just been peeled off from casting belt (1), because solvent evaporates from casting belt (1) binding face side, temperature reduces rapidly at short notice, the volatile ingredients such as the steam in the atmosphere gas, solvent vapour are easily concentrated, the temperature of sheet stock is 5～30 ℃ when therefore, more preferably peeling off.

Herein, the residual solvent amount represents with following formula.

Residual solvent amount (quality %)=(M-N)/N} * 100

In the formula, M is the quality of the sample that any time point is taked in making the sheet stock process, and N is to the quality of M heating after 3 hours under 110 ℃.

In addition, extensibility represents with following formula.

Distance: h between the clip of tenter frame in the stretching process (5) front; Distance: H between the clip when tenter frame in the stretching process (5) finishes.

Extensibility=H/h * 100%

The rubber cement film (sheet stock) that is formed by the rubber cement of curtain coating on casting belt (1) is heated at casting belt (1), and evaporating solvent is until can peel off sheet stock by stripper roll (3) from casting belt (1).

During evaporating solvent, can adopt the method for being conducted heat by surface and the back side from the method for sheet stock cross air blasting and/or the method for conducting heat from the back side of casting belt (1) by liquid, by radiant heat etc.

Film easily is stretched at throughput direction when peeling off, film shrinks on width, so preferably peeling off under the condition that tension force is strippable minimum tension force～170N/m when peeling off sheet stock (10) by stripper roll (3) from casting belt (1) peeled off, and more preferably peels off under the condition of minimum tension force～140N/m.

Go up sheet stock (10) dry solidification to strippable film-strength at casting support (1), peel off sheet stock (10) by stripper roll (3), subsequently, with tenter frame (5) the stretching sheet stock (10) in the stretching process.

Residual solvent amount in tenter frame (5) sheet stock (film) (10) before in the preferred input stretching process is 10～35 quality %.

In stretching process, go out slit mouth (5a) from the hot blasting device instant heating wind of the forward part in tenter frame (5) bottom and be blown into hot blast (11), outlet (5b) from tenter frame (5) top by the rear section is discharged exhaust wind (12), sheet stock (10) can be carried out drying when stretching like this.

And, about the hot blasting device in the stretching process of the present invention, specifically, blow out slit mouth (5a) corresponding to the hot blast of tenter frame in the stretching process (5), so long as by blowing out hot blast effectively the shape of heating film get final product, be not particularly limited.Can list for example illustrated shape of slit or perforated plate shape.

In the present invention, the extensibility of the sheet stock in the tenter frame of stretching process (5) is 20～60%, and for the glass transition temperature (Tg) of coiling caudacoria, the temperature that the hot blast from tenter frame (5) blows out the hot blast (11) that slit mouth (5a) blows out is Tg+35 ℃～Tg+80 ℃.In addition, more preferably this temperature is Tg+40 ℃～Tg+50 ℃.

Here need to prove, if the extensibility of the sheet stock (10) in the tenter frame of stretching process (5) is lower than lower limit, then can't obtain the wide film of width, therefore not preferred.In addition, if the extensibility of the sheet stock (10) in the tenter frame (5) is higher than higher limit, then the mist degree of film increases, and the optical transmission rate reduces, so in the liquid crystal indicator of packing into the time, contrast reduces, and is therefore not preferred.

In addition, be lower than lower limit if blow out the temperature of the hot blast (11) that slit mouth (5a) blows out from the hot blast of the tenter frame (5) of stretching process, during then because of stretching film is caused unnecessary stress, mist degree is increased, the optical transmission rate reduces, contrast reduces during liquid crystal indicator so pack into, and is therefore not preferred.In addition, be higher than higher limit if blow out the temperature that slit mouth (5a) blows out hot blast (11) from the hot blast of tenter frame (5), then film is softening, loses self-supporting, and, clip section sheet stock inner at tenter frame breaks, and be therefore not preferred.

, as long as hot blast (11) temperature in the tenter frame (5) of stretching process is more than Tg+35 ℃, can obtain the wide film of width herein, therefore preferred.In addition, if hot blast (11) temperature in the tenter frame of stretching process (5) is below Tg+80 ℃, then the mist degree of film can not increase, and the optical transmission rate is high, in the time of in the liquid crystal indicator of packing into, can prevent the reduction of contrast, and is therefore preferred.

The drying process after casting belt (1) is peeled off, because the evaporation of solvent, sheet stock (or film) (10) can shrink at width.Dry under higher temperature, shrink larger.Preferably carry out drying in the situation that suppress as far as possible contraction, so that the flatness of the film of making is good.

Described width in the preferred stretching process keeps or the stretching of transverse direction is undertaken by tenter frame (5), also can use needle plate tenter frame, clip tenter frame.

Present embodiment for example has 2 organic principles and removes device (removing equipment) (13a) (13b), this removes the small-molecular weight organic principle (plasticizer etc.) that exhaust wind (12) that device is used for removing the tenter frame (5) from stretching process contains, and the organic principle concentration of removing in the exhaust wind (14) of device (13a) after (13b) by these organic principles is 1～100 μ g/m ³

In addition, in the present embodiment, again will through organic principle remove device (13a) (13b) the exhaust wind (14) after removing organic principle be the part of dry wind (11) as the hot blast of the tenter frame in the part stretching process (5) upstream, recycle.In addition, (13b) be illustrated as 2 although organic principle is removed device (13a), can have the multistage organic principle and remove device, for example 2～4 organic principles of preferred continuously installation are removed device (13a) (13b).

Tenter frame in stretching process (5) arranges rear drying device (6) afterwards.In rear drying device (6), from the side, by being configured in a zigzag (Qian Birds) a plurality of conveying rollers (7) that sheet stock (10) is wriggled is defeated

Send, make during this period sheet stock (10) drying.In addition, the film conveyance tension in the rear drying device (6) is subjected to the physical property of rubber cement, when peeling off and film carry the residual solvent amount in the operation, the impacts such as temperature in the rear drying device (6), be preferably 30～250N/m, more preferably 60～150N/m.80～120N/m most preferably.

And the method for dry sheet stock (or film) (10) is not particularly limited, and usually carries out with hot blast, infrared ray, warm-up mill, microwave etc.From easily angle consideration, preferably use heated-air drying, the dry wind (15) that for example is blown into by the hot-wind inlet by the forward part in rear drying device (6) bottom carries out drying, carries out drying by discharging exhaust wind (16) by rear drying device (6) top by the outlet of rear section.The temperature of preferred dry wind (15) is 40～160 ℃, in order to improve flatness, dimensional stability, more preferably 50～160 ℃.

These can carry out under air atmosphere gas from the operation that is cast to rear drying, also can carry out under the non-active gas atmosphere gas such as nitrogen.Certainly, consider and to consider the blast critical concentration of solvent in dry atmosphere gas.

Sheet stock conveyance tension when dry is 30～300N/m, more preferably 40～270N/m.

Preferably after operation dry after be cast to, sheet stock (10) cleaning surfaces gasifying device is set.

Clean device not only to carrying the sheet stock (10) in the way to apply ultrasonic wave vibration, and aim at the surface and give high-pressure blast, blow away attachment, the dust that remove attraction, adheres to etc.In addition, also can adopt and carry out the scorching mode of processing (sided corona treatment, plasma treatment) of fire, known device, the methods such as mode of adhesive roller are set, but be not limited to this.And cleaning device and can using separately of configuration also can will be used in combination more than 2.

In most cases dust etc. is by electrostatic interaction to adhering to of sheet stock (10), therefore preferably Destaticizing device is set before cleaning device and for example destatics rod above-mentioned, removes the static of sheet stock (10).Destaticing rod can use known goods to be not particularly limited.

At drying process, the evaporation of the plasticizer that contains in the sheet stock (10) as the countermeasure that suppresses the condensation that plasticizer occurs at roller, wall, preferably passes into live gas more than the specified quantitative with respect to the air quantity of supplying with in the unit interval.And preferably the amount with the live gas supplied with is set as 5～50% of full supply air quantity.

The live gas quantity delivered is made as 5～50% because: if quantity delivered less than 5%, then live gas is very few, can't suppress the plasticizer condensation fully, if greater than 50%, then the virgin gas scale of construction is too much, considers from operating cost, waste is serious.

In order to prevent that film preferably arranges tension force cut-off roller (tension cut roll) along the stretching of throughput direction in rear drying device (6).After drying finishes, before reeling, guillotine (Slitter) is set, cuts the end, can obtain good reeling condition, therefore preferred.

For the cellulose ester membrane of having finished rear drying process (6), before it is imported coiling process, by being set, the embossing processing unit (plant) is implemented in the processing that forms embossing on the film.

Here, the height h of embossing (μ m) is set as 0.05～0.3 times the scope of the thickness T of film, and width W is set as 0.005～0.02 times the scope of film width L.Embossing can form on the two sides of film.In this case, the height h1+h2 of embossing (μ m) is set as 0.05～0.3 times the scope of the thickness T of film, and width W is set as 0.005～0.02 times the scope of film width L.For example, when the thickness of film was 40 μ m, the height h1+h2 of embossing (μ m) was set as 2～12 μ m.Embossing width is set as 5～30mm.

Width for embossing, because embossed portion finally can become the part of loss, thus wish that the width of embossing is little, for example, adopting 50 μ m with interior film, when carrying out the high speed masking more than 50m/ minute, embossing width is the width of minimum necessary limit that can suppress the slip of film.But, need to be associated with aforesaid embossed height, come to determine eliminate all these embossed height * embossing width of pyramid shape, horseback, polygon, coiling deviation fault.And embossing not only can be configured in the both ends of film, can also be configured in the central portion part.

In the present invention, preferably before batching and after just having batched, static eliminator is set, film is destaticed.

Static eliminator can adopt following formation to destatic, so that the hot-line electrical potential of repeatedly extracting film when volume out for ± below the 2KV: when batching by Destaticizing device or force Charging system to give the formation of counter potential, the perhaps formation by forcing hot-line electrical potential to destatic with the static eliminator of the positive and negative mutual conversion of 1～150Hz.

In addition, can also utilize the ion generator that produces ion wind or destatic rod and replace above-mentioned static eliminator.Here, ion generator destatics and is performed such, to from the embossing processing unit (plant) through the film that conveying roller batches, blow ion wind.Ion wind is produced by static eliminator.As static eliminator, can use known static eliminator and unrestricted.

At the dry complete film of reeling by coiler device (8), thereby in the operation that the film that obtains blooming is rolled up, by making the residual solvent amount that finishes dry film (20) be below the 0.5 quality %, below the preferred 0.1 quality %, can obtain the good film of dimensional stability.

The method for winding of film can use normally used volume film machine, have decide Torque method, decide tensammetry, method that taper tension method, the certain program of internal stress are opened the control tension force such as force controlling method, can distinguish use to these methods.

Film can use the two sides adhesive tape, also can use the single face adhesive tape with engaging of scroll core (volume core).

The width of the film after cellulose ester membrane of the present invention is preferably reeled is 1650～2500mm.

In the present invention, from the angle of the slimming of liquid crystal indicator, the dried thickness of cellulose ester membrane is in finished film, the scope of preferred 40～80 μ m.Here, the thickness of dried film is with regard to the film under the state below the residual solvent amount in the film is 0.5 quality %.

Here, if the thickness of the cellulose ester membrane after reeling is excessively thin, then sometimes can not obtain as for example necessary intensity of protective film for polarizing plate.The thickness of film is blocked up, has then lost the advantage of filming with respect to traditional cellulose ester membrane.The adjusting of thickness can be controlled the slit gap, the extrusion pressure of casting head, the speed of casting support etc. of joint of liquor charging amount, the casting head of rubber cement concentration, pump, so that reach desired thickness.In addition, as the method that makes the thickness homogeneous, preferably use film thickness detecting device, the feedback information of sequencing is fed back to above-mentioned each device regulate.

Undertaken by solution casting masking method after curtain coating just to the operation of drying, the atmosphere gas in the drying device can be air, also can carry out in the inactive atmosphere gas such as nitrogen, carbon dioxide.But, the certainly common danger that must consider the explosion limit of evaporating solvent in dry atmosphere gas.

In the present invention, the moisture content of cellulose ester membrane is preferably 0.1～5%, and more preferably 0.3～4%, more preferably 0.5～2%.

In the present invention, the transmissivity of wishing cellulose ester membrane is more than 90%, more preferably more than 92%, more preferably more than 93%.

In addition, because the mist degree of 3 cellulose ester membranes by method manufacturing of the present invention when overlapping is 0.3～2.0, therefore, cellulose ester membrane of the present invention is that the film mist degree is very low, has the good transparency, the optical characteristics of flatness.

In the present embodiment, direction delay (Ro) is 30～300nm under the condition of 23 ℃ of temperature, humidity 55%RH in the face of following formula definition, and thickness direction retardation (Rt) is 70～400nm under the condition of 23 ℃ of temperature, humidity 55%RH.

Ro＝(nx-ny)×d

Rt＝{(nx+ny)/2-nz}×d

(in the formula, Ro represents that length of delay, Rt represent that film thickness direction length of delay, nx represent that flexion rate, the ny of slow-axis direction in the face represent that the flexion rate of quick shaft direction in the face, flexion rate (the flexion rate is measured), the d that nz represents film thickness direction represent film thickness (nm) under wavelength 590nm in the face.)

And length of delay Ro, Rt can measure with automatic birefringence meter (Complex flexion rate Meter).For example, with KOBRA-21 ADH (manufacturing of prince's instrumentation machine Co., Ltd.), under the environment of 23 ℃ of temperature, humidity 55%RH, under wavelength 590nm, measure.

Cellulose ester membrane by method manufacturing of the present invention can be used for liquid crystal and represents to use parts, in detail, is preferred for protective film for polarizing plate.Particularly, to moisture permeability and dimensional stability all in the strict protective film for polarizing plate, the preferred cellulose ester membrane that adopts method of the present invention to make that uses.

By using the protective film for polarizing plate of being made by the cellulose ester membrane of present embodiment, can provide filming and durability and dimensional stability, the good polarizer of optical isotropy.

, light polarizing film is the film that uses traditionally, but such as the film of the stretch orientations such as polyvinyl alcohol film being processed with dichroic dyes such as iodine and longitudinal stretching and the film that obtains.Light polarizing film itself does not have sufficient intensity, durability, and the anisotropic cellulose ester membrane that do not have of therefore usually fitting on its two sides as diaphragm is used as polarizer.

Also can fit and adopt the cellulose ester membrane of method manufacturing of the present invention to make above-mentioned polarizer as phase retardation film; in addition; also can be with the cellulose ester membrane that adopts method of the present invention to make simultaneously as phase retardation film and diaphragm, it directly is fitted in makes above-mentioned polarizer on the light polarizing film.The method of fitting is not particularly limited, and can be undertaken by the adhesive of being made by the aqueous solution of water-soluble polymer.

This water-soluble copolymer adhesive preferably uses fully saponified type polyvinyl alcohol water solution.Further, stretch at length direction, the phase retardation film by fitting and making through rectangular light polarizing film and the rectangular employing method of the present invention of dichroic dye processing can obtain rectangular polarizer.Polarizer also can be made into by pressure-sensitive adhesive layer (such as, acrylic compounds pressure-sensitive adhesive layer etc.) its single face or two sides lamination the fit type polarizer of stripping film (by peeling off stripping film, can easily be fitted on liquid crystal cell etc.).

The polarizer that obtains like this can be used for various display unit.Especially preferably used the liquid crystal indicator of following liquid crystal cell, described liquid crystal cell comprises, when not applying voltage the vertical orientated in fact VA pattern of liquid crystal liquid crystal property molecule, when not applying voltage liquid crystal liquid crystal property molecule level and reverse the liquid crystal cells of the TN pattern of (ね じ れ) orientation in fact.

Polarizer can adopt usual way to make.For example, comprise following method: blooming or cellulose ester membrane are carried out the alkali soap processing, use fully saponified type polyvinyl alcohol water solution that it is fitted in the polyvinyl alcohol film two sides of the light polarizing film of making and obtaining of flooding, stretch in iodine solution.The alkali soap processing refers to for the infiltration that makes aqueous binder improves, improves zygosity, and cellulose ester membrane be impregnated in the processing in the aqueous alkali of high temperature.

Cellulose ester membrane for the method manufacturing of adopting present embodiment can also be given the various functional layers such as hard conating, antiglare layer, anti-reflection layer, stain-proofing layer, antistatic backing, conductive layer, optical anisotropic layer, liquid crystal layer, oriented layer, tack coat, knitting layer, bottom.These functional layers can adopt the methods such as coating or evaporation, sputter, plasma CVD, atmospheric plasma treatment to arrange.

The polarizer that obtains like this can be arranged on single face or the two sides of liquid crystal cells, uses this polarizer can obtain liquid crystal indicator.

In the present invention; liquid crystal indicator has: seize liquid crystal cell and 2 polarizers that bar-shaped liquid crystal molecule forms on both sides by the arms by a pair of glass substrate, described polarizer is made of the light polarizing film that is configured to the holding liquid crystal box and the protective clear layer that is configured in the light polarizing film both sides.

By using the protective film for polarizing plate that is consisted of by the cellulose ester membrane that adopts method manufacturing of the present invention, when can be provided in filming, durability, dimensional stability, the good polarizer of optical isotropy.And, used the display performance that the liquid crystal indicator of this polarizer or phase retardation film can stable for extended periods of time.

The matrix material that can be used as antireflection film or optical compensation films with the cellulose ester membrane of the method manufacturing of present embodiment uses.

Embodiment

Below, be described more specifically the present invention by embodiment, but the present invention is not subjected to the restriction of these embodiment.

Embodiment 1

(rubber cement forms 1)

Cellulosic triacetate 100 mass parts

(Mn＝148000、Mw＝310000、Mw/Mn＝2.1)

Triphenyl phosphate 8 mass parts

Phthalyl ethyl ester ethyl glycolate (ethly phthalyl-ethly glycolate)

2 mass parts

Carrene 440 mass parts

Ethanol 40 mass parts

Tinuvin 109 (manufacturing of Ciba Specialty Chemicals company) 0.5 mass parts

Tinuvin 171 (manufacturing of Ciba Specialty Chemicals company) 0.5 mass parts

AEROSIL972V (Japanese AEROSIL Co., Ltd. make) 0.2 mass parts

Above-mentioned material is joined in the closed container successively, the temperature in the container is warming up to 80 ℃ from 20 ℃ after, temperature is remained on 80 ℃ stirred 3 hours, cellulosic triacetate is dissolved fully.Then, stop to stir, make liquid temperature drop to 43 ℃.Use filter paper (the long-pending filter paper Co., Ltd. of peace makes, pacifies long-pending filter paper No.244) that this rubber cement is filtered, obtained rubber cement.

Use casting support formula solution casting film forming apparatus shown in Figure 1, the rubber cement of the above-mentioned modulation of curtain coating equably on support (1), the rubber cement film (sheet stock) that curtain coating forms is upper dry at support (1), when sheet stock arrives the lower surface of the support of being made by the endless belt and basically centers on a week, by stripper roll (3) sheet stock (film) (10) is peeled off from support (1), described support (1) rotates stainless steel endless belt through the driving on the surface of mirror process and makes by having.

Then, the sheet stock after peeling off (10) is imported tenter frame (5), clamp the sheet stock two ends with clip, in the situation that keep width, the hot blast (11) that blows 160 ℃ carries out drying, simultaneously sheet stock (10) is stretched at width.

Here, be 12 quality % with the residual solvent amount that namely will enter tenter frame (5) sheet stock (film) (10) before of stretching process.

Then, making the extensibility of sheet stock in the tenter frame (5) of stretching process is 20%, and the temperature that makes hot blast in the tenter frame (5) blow out the hot blast (11) that slit mouth (5a) blows out is 160 ℃.Here, the temperature of the hot blast (11) in the tenter frame (5) is with respect to the glass transition temperature of the cellulosic triacetate film after reeling: Tg=125 ℃, and namely Tg+35 ℃.

In addition, in this embodiment, have two continuous organic principles and remove device (13a) (13b), organic principle beyond the solvent that comprises in its exhaust wind (12) with tenter frame (5) is removed, and the small-molecular weight organic principle concentration of removing in the exhaust wind (14) of device (13a) after (13b) by these organic principles is 20 μ g/m ³

And the mensuration of contained organic principle is performed such in the exhaust wind (12) of tenter frame (5): get the exhaust wind air of certain volume, adopt GC/MS to analyze under air-tight state.

Like this, removing exhaust wind (14) that device (13a) (13b) removed organic principle by organic principle is recycled as the part of the hot blast (11) of tenter frame (5) upstream again.

Then, use to possess and it seems from the side and be the in a zigzag roller transport drying device (6) of a plurality of minute surface conveying rollers (7) of configuration, carry out drying with 100 ℃ dry winds (15) for sheet stock (film) (10).The film that drying is complete (20) is reeled with coiler device (8), has finally obtained the cellulosic triacetate film (20) of thickness 80 μ m, film width: 1860mm.

In addition, embossing processing is implemented at the both ends of the width that is wound on the cellulose ethanoate film on the take up roll, making the height of the protuberance that is processed to form by embossing is the scope of 4～12 μ m, and to make the difference in height of the protuberance by embossing processing be below the 2 μ m.

Remove or reduce the device of the surface potential of cellulose ethanoate film during as coiling, used to destatic air blast (Block ロ ア).

Put down in writing the kind of the rubber cement composition of the manufacturing that is used for the cellulosic triacetate film in the following table 1, the extensibility (%) of sheet stock (10), hot blast in the tenter frame of stretching process (5) blow out the hot blast (11) that slit mouth (5a) blows out temperature (℃), the glass transition temperature (Tg) of the cellulosic triacetate film behind the coiling (℃), residual solvent amount (%) when being about to enter the entering of the front sheet stock (10) of tenter frame (5), and thickness (μ m).

Next, measure the haze value of the cellulosic triacetate film of this embodiment 1 gained, acquired results is shown in following table 1.

Here, the following mensuration of the mist degree of cellulosic triacetate film.Namely, film to the casting film gained is taken a sample, and from wherein selecting at random 10 positions, presses the method for JIS K6714 regulation, 3 of cellulosic triacetate films are overlaped, use haze meter (1001DP type, Japanese electric look Industrial Co., Ltd make) to measure its mist degree.

Embodiment 2～15

As above-described embodiment 1, use rubber cement to form 1 and make the cellulosic triacetate film, but in each embodiment, as following a part of film forming condition is changed.

At first, in embodiment 2, undertaken by condition substantially the same manner as Example 1, but the extensibility of sheet stock (10) in the tenter frame (5) of stretching process is changed into 30 (%).

In embodiment 3 and 4, by carrying out with embodiment 1 and 2 essentially identical conditions, but it is 170 ℃ with the temperature change that the hot blast from tenter frame (5) blows out the hot blast (11) that slit mouth (5a) blows out.

In embodiment 5 and 6, by carrying out with embodiment 1 and 2 essentially identical conditions, but it is 180 ℃ with the temperature change of hot blast (11).

In embodiment 7, undertaken by condition substantially the same manner as Example 5, but the extensibility of sheet stock (10) is changed into 40 (%).

In embodiment 8, undertaken by condition substantially the same manner as Example 7, but the extensibility of sheet stock (10) is changed into 55 (%), and the residual solvent amount is changed into 35 (%) will be about to enter the entering of tenter frame (5) sheet stock (10) before the time.

In embodiment 9, undertaken by condition substantially the same manner as Example 7, but be 200 ℃ with the temperature change of hot blast (11).

In embodiment 10, undertaken by condition substantially the same manner as Example 9, but the residual solvent amount is changed into 35 (%) will be about to enter the entering of tenter frame (5) sheet stock (10) before the time.

In embodiment 11, undertaken by condition substantially the same manner as Example 10, but the extensibility of sheet stock (10) is changed into 60 (%).

In embodiment 12 and 13, undertaken by condition substantially the same manner as Example 6, but the residual solvent amount that will be about to enter tenter frame (5) sheet stock (10) is before changed into respectively 20 quality %, 35 quality %.

In embodiment 14 and 15, undertaken by condition substantially the same manner as Example 6, but the thickness of film is changed into respectively 40 μ m, 60 μ m.

Comparative example 1～6

In order to compare, use the rubber cement of above-described embodiment 1 to form 1 making cellulosic triacetate film, different from above-described embodiment 1 is: in comparative example 1 and 6, make the extensibility (%) of sheet stock (10) in the tenter frame (5) be 18% and 65% outside the scope of the invention; In comparative example 2～5, make from tenter frame (5) hot blast blow out the temperature of the hot blast (11) that slit mouth (5a) blows out all outside scope of the present invention.

And, in comparative example 6, the cellulosic triacetate film that forms 1 making thickness, 80 μ m for the rubber cement that uses above-described embodiment 1, mode by above-described embodiment 1 is implemented, but in tenter frame (5) with sheet stock (10) when being stretched to extensibility 65%, sheet stock (10) fracture can't be made film.

In following table 1, put down in writing in embodiment 2～15 and the comparative example 1～6 kind that the rubber cement for the manufacture of the cellulosic triacetate film forms, the extensibility (%) of sheet stock (10), hot blast from the tenter frame (5) of stretching process blow out the hot blast (11) that slit mouth (5a) blows out temperature (℃), the glass transition temperature of cellulosic triacetate film (Tg) (℃), residual solvent amount (%) and thickness (μ m) when being about to enter the entering of tenter frame (5) sheet stock (10) before.

Then, for the cellulosic triacetate film of embodiment 2～15 and comparative example 1～5 gained, measure the haze value of film as above-mentioned embodiment 1, acquired results is shown in following table 1.

Embodiment 16

Use following rubber cement to form 2, by implementing with above-described embodiment 1 essentially identical mode, made cellulose ethanoate propionic ester film.

(rubber cement forms 2)

Cellulose ethanoate propionic ester 100 mass parts

(degree of substitution with acetyl group+propiono substitution value=2.45, Mn=60000, Mw=180000, Mw/Mn=3.00)

Triphenyl phosphate 8 mass parts

Phthalyl ethyl ester ethyl glycolate 2 mass parts

Carrene 360 mass parts

Ethanol 60 mass parts

Tinuvin 109 (manufacturing of Ciba Specialty Chemicals company) 0.5 mass parts

Tinuvin 171 (manufacturing of Ciba Specialty Chemicals company) 0.5 mass parts

AEROSIL 972V (Japanese AEROSIL Co., Ltd. make) 0.2 mass parts

In embodiment 16, the residual solvent amount that is about to enter tenter frame (5) sheet stock (10) before of stretching process is 12 quality %, make the extensibility of sheet stock (10) in the tenter frame (5) is 25%.In addition, the temperature that makes from tenter frame (5) hot blast blow out the hot blast (11) that slit mouth (5a) blows out is respectively 185 ℃.

Here, for the glass transition temperature Tg of the cellulose ethanoate propionic ester film after reeling=145 ℃, the temperature of the hot blast (11) in the tenter frame (5) is Tg+40 ℃.The thickness of the cellulose ethanoate propionic ester film behind the coiling is 40 μ m.

Embodiment 17～26

As above-described embodiment 16, use rubber cement to form 2 and make the cellulose ethanoate propionic esters, but in each embodiment as change a part of film forming condition followingly.

At first, in embodiment 17 and 18, undertaken by condition substantially the same manner as Example 16, but the extensibility of the sheet stock (10) in the tenter frame (5) of stretching process is changed into 35 (%), 40 (%).

In embodiment 19, undertaken by condition substantially the same manner as Example 16, but the extensibility of the sheet stock (10) in the tenter frame (5) of stretching process is changed into 60 (%), and the temperature change that will blow out from the hot blast of tenter frame (5) hot blast (11) that slit mouth (5a) blows out is 180 ℃.

Among the embodiment 20, undertaken by condition substantially the same manner as Example 18, but the temperature change that will blow out from the hot blast of tenter frame (5) hot blast (11) that slit mouth (5a) blows out is 200 ℃.

Among the embodiment 21～23, undertaken by condition substantially the same manner as Example 17, but the residual solvent amount is changed into respectively 10 (%), 20 (%), 35 (%) will be about to enter the entering of tenter frame (5) sheet stock (10) before the time.

Among the embodiment 24～26, undertaken by condition substantially the same manner as Example 17, but the thickness of film is changed into respectively 50 μ m, 60 μ m, 80 μ m.

Comparative example 7～9

In order to compare, use the rubber cement of above-described embodiment 16 to form 2, make cellulose ethanoate propionic ester film, different from above-described embodiment 16 is: make from the hot blast of tenter frame (5) and blow out the temperature of the hot blast (11) that slit mouth (5a) blows out all outside scope of the present invention.

Following table 1 has been put down in writing the kind that the rubber cement for the manufacture of cellulose ethanoate propionic ester film in embodiment 16～26 and the comparative example 7～9 forms, the extensibility (%) of sheet stock (10), hot blast from tenter frame (5) blow out the hot blast (11) that slit mouth (5a) blows out temperature (℃), the glass transition temperature (Tg) of the cellulose ethanoate propionic ester film behind the coiling (℃), residual solvent amount (%) and thickness (μ m) during the entering of film in the tenter frame (5).

Then, for embodiment 16～26 and comparative example 7～9 gained cellulose ethanoate propionic ester films, measured the haze value of film as above-described embodiment 1, acquired results as described in Table 1.

Comparative example 10

In order to compare, use following rubber cement to form 3, by implementing with above-described embodiment 1 essentially identical mode, made the cellulosic triacetate film.

(rubber cement forms 3)

Cellulosic triacetate 100 mass parts

(Mn＝148000、Mw＝310000、Mw/Mn＝2.1)

Carrene 440 mass parts

Ethanol 40 mass parts

AEROSIL972V (Japanese AEROSIL Co., Ltd. make) 0.2 mass parts

Here, making the residual solvent amount of tenter frame (5) sheet stock (film) (10) before that is about to enter stretching process is 12 quality %.

And making that the extensibility of sheet stock is 30% in the tenter frame (5), making the temperature that blows out the hot blast (11) that slit mouth (5a) blows out from the hot blast of tenter frame (5) is 180 ℃.Here, for the glass transition temperature Tg of the cellulosic triacetate film after reeling=110 ℃, the temperature of the hot blast (11) in the tenter frame (5) is Tg+70 ℃.

The rubber cement of this comparative example 10 forms in 3 not plasticizer-containing, therefore sheet stock (10) is stretched to extensibility 10% in tenter frame (5) when above, and fracture can't be made film.

Table 1

	Rubber cement forms	Extensibility (%)	The stretching process hot blast temperature (℃)	Film Tg (℃)	Residual solvent amount (quality %) when entering	Thickness (μ m)	Mist degree
								Embodiment 1	1	20	160	125	12	80	0.5
Embodiment 2	1	30	160	125	12	80	0.8
								Embodiment 3	1	20	170	125	12	80	0.5
Embodiment 4	1	30	170	125	12	80	0.7
								Embodiment 5	1	20	180	125	12	80	0.5
Embodiment 6	1	30	180	125	12	80	0.6
								Embodiment 7	1	40	180	125	12	80	0.9
Embodiment 8	1	55	180	125	35	80	1.7
								Embodiment 9	1	40	200	125	12	80	0.7
Embodiment 10	1	40	200	125	35	80	0.5
								Embodiment 11	1	60	200	125	35	80	1.5
Embodiment 12	1	30	180	125	20	80	0.5
								Embodiment 13	1	30	180	125	35	80	0.4
Embodiment 14	1	30	180	125	12	40	0.3
								Embodiment 15	1	30	180	125	12	60	0.4
Embodiment 16	2	25	185	145	12	40	0.3
								Embodiment 17	2	35	185	145	12	40	0.4
Embodiment 18	2	40	185	145	12	40	0.5
								Embodiment 19	2	60	180	145	12	40	1.4
Embodiment 20	2	40	200	145	12	40	0.2
								Embodiment 21	2	35	185	145	10	40	0.5
Embodiment 22	2	35	185	145	20	40	0.3
								Embodiment 23	2	35	185	145	35	40	0.2
Embodiment 24	2	35	185	145	12	50	0.4
								Embodiment 25	2	35	185	145	12	60	0.4
Embodiment 26	2	35	185	145	12	80	0.6
								Comparative example 1	1	18	205	125	8	80	2.5
Comparative example 2	1	30	135	125	8	80	5.1
								Comparative example 3	1	42	206	125	8	80	7.2
Comparative example 4	1	30	206	125	8	80	6.1
								Comparative example 5	1	42	206	125	40	80	6.5
Comparative example 6	1	65	170	125	12	80	-
								Comparative example 7	2	45	145	145	8	80	5.8
Comparative example 8	2	42	155	145	8	80	3.2
								Comparative example 9	2	42	155	145	40	80	3.5

By the result of above-mentioned table 1 as can be known: according to the cellulose ester membrane of embodiments of the invention 1～26; make in the method for cellulose ester membrane in employing solution casting masking legal system; even can make through too high stretching; the mist degree of film also can not raise and the good cellulose ester membrane of optical characteristics such as transparency, flatness; can improve simultaneously speed of production, improve the productivity of film, and then can adapt to the requirement of filming, wide cut and high-qualityization of protective film for polarizing plate in recent years etc.

In contrast, for the cellulose ester membrane of comparative example 1～5 and comparative example 7～9 gained, stretch if carry out height, then the mist degree of film raises, and the transparency, flatness reduce.Therefore, can't improve the speed of production of cellulose ester membrane, also can't improve the productivity of film, can not adapt to the requirement of filming, wide cut and high-qualityization of protective film for polarizing plate etc.

Embodiment 27

(making of light polarizing film)

In order to make LCD panel shown in Figure 2, at first made light polarizing film.That is, the polyvinyl alcohol film of thickness 120 μ m carried out simple tension at 110 ℃ of stretching ratios with 5 times of temperature.It was flooded 60 seconds in the aqueous solution that is comprised of iodine 0.075g, KI 5g, water 100g, then in 68 ℃ the aqueous solution that is formed by KI 6g, boric acid 7.5g, water 100g, flood.It is washed and drying, obtained light polarizing film.

(making of polarizer)

Then, by following operation 1～operation 5, the cellulose ethanoate propionic ester film (T-2) of the thickness 40 μ m that the cellulosic triacetate film (T-1) of the thickness 80:m that applying embodiment 6 makes on above-mentioned light polarizing film and embodiment 21 make has been made polarizer 1.Operation 1: dipping is 60 seconds in the sodium hydroxide solution of 50 ℃ 2 mol/L, then washing and dry, and a side that has obtained fitting with light polarizing film has been passed through the T-1 of saponification, T-2 film.

Operation 2: light polarizing film was flooded 1～2 second in solid constituent is the poly (vinyl alcohol) binder groove of 2 quality %.

Operation 3: wipe out gently the unnecessary adhesive that is attached in the operation 2 on the light polarizing film, at the T-1 that the both sides of this light polarizing film stacked arrangement obtains through the processing of operation 1, T-2 film.

Operation 4: with light polarizing film and the T-1 of configuration in the operation 3, the T-2 film is with 20～30N/cm ²Pressure, approximately 2m/ minute transporting velocity fit.

Operation 5: with the light polarizing film and the T-1 that make in the operation 4, dry 2 minutes of T-2 film has been made polarizer 1 in 80 ℃ drying machine.

Then, as the polarizer 2 of the another side that is fitted in LCD panel, utilize the mode as above-mentioned making polarizer 1, be configured so that its applying direction for centered by liquid crystal with polarizer 1 symmetry.

Thereby as shown in table 2, the film T-3 of polarizer 2 is the cellulose ethanoate propionic ester film of the thickness 40 μ m of making among the embodiment 21, and the film T-4 of polarizer 2 is the cellulosic triacetate film of the thickness 80 μ m of making among the embodiment 6.

(making of LCD panel)

Then, peel off respectively carefully commercially available LCD panel (NEC colour liquid crystal display device processed, MultiSync, LCD1525J: the polarizer on two sides model LA-1529HM), at polarizer 1 and the polarizer 2 of the above-mentioned making of this liquid crystal applying, made LCD panel.

At this moment, as shown in Figure 2, fit, so that with respect to the liquid crystal of central authorities, as the cellulosic triacetate film (T-1) of thickness 80 μ m polarizer 1 and polarizer 2, that make among the embodiment 6 and (T-4) lay respectively at the outside, the cellulose ethanoate propionic ester film (T-2) of the thickness 40 μ m of making and (T-3) lay respectively at central liquid crystal side among the embodiment 21.

In this case, outer side form (T-1) side of polarizer 1 is the demonstration side of LCD panel, and the outer side form (T-4) of polarizer 2 is (backlight) backlight side.

For the LCD panel of the embodiment 27 that obtains like this, measure its contrast, acquired results is shown in following table 2.

(contrast when measuring the display board installation)

The mensuration of the contrast when display board is installed is implemented by the angle of visual field of estimating display board.Here, angle of visual field evaluation is to make EZ-contrast with ELDIM company to come LCD panel is measured the angle of visual field.Assay method is as follows: for the contrast during for the white demonstration of LCD panel and black the demonstration, according to tilt contrast on the direction at 80 ° of angles of the normal direction of slave plate face, carry out classification in the scope in following value on comprehensive.

◎ ◎ ◎: contrast comprehensive be more than 40

◎ ◎: contrast comprehensive be more than 30

◎: contrast comprehensive be more than 20

Zero: contrast comprehensive be more than 15

△: be more than 5 but less than 15 zone in the comprehensive contrast that exists

*: in the comprehensive contrast that exists less than 5 zone

Embodiment 28～31

As embodiment 27, make LCD panel, but as follows with the difference of above-described embodiment 27.

Among the embodiment 28, the cellulose ethanoate propionic ester film (T-2) of the thickness 60 μ m that make among the cellulosic triacetate film (T-1) of the thickness 80 μ m that make among the applying embodiment 6 on light polarizing film and the embodiment 25 is made polarizer 1, polarizer 2 as the another side that is fitted in LCD panel, utilized the mode such as above-mentioned making polarizer 1, be configured so that its applying direction is symmetrical centered by liquid crystal.

Thereby as shown in table 3, the film T-3 of polarizer 2 is the cellulose ethanoate propionic ester film of the thickness 60 μ m of making among the embodiment 25, and the film T-4 of polarizer 2 is the cellulosic triacetate film of the thickness 80 μ m of making among the embodiment 6.

Among the embodiment 29, the cellulose ethanoate propionic ester film (T-2) of the thickness 80 μ m that make among the cellulosic triacetate film (T-1) of the thickness 80 μ m that make among the applying embodiment 6 on light polarizing film and the embodiment 26 is made polarizer 1, polarizer 2 as the another side that is fitted in LCD panel, utilized the mode such as above-mentioned making polarizer 1, be configured so that its applying direction is symmetrical centered by liquid crystal.

Thereby as shown in table 2, the film T-3 of polarizer 2 is the cellulose ethanoate propionic ester film of the thickness 80 μ m of making among the embodiment 26, and the film T-4 of polarizer 2 is the cellulosic triacetate film of the thickness 80 μ m of making among the embodiment 6.

Among the embodiment 30, the cellulose ethanoate propionic ester film (T-2) of the thickness 60 μ m that make among the cellulosic triacetate film (T-1) of the thickness 80 μ m that make among the applying embodiment 13 on light polarizing film and the embodiment 25 is made polarizer 1, polarizer 2 as the another side that is fitted in LCD panel, utilized the mode such as above-mentioned making polarizer 1, be configured so that its applying direction is symmetrical centered by liquid crystal.

Thereby as shown in table 2, the film T-3 of polarizer 2 is the cellulose ethanoate propionic ester film of the thickness 60 μ m of making among the embodiment 25, and the film T-4 of polarizer 2 is the cellulosic triacetate film of the thickness 80 μ m of making among the embodiment 13.

Among the embodiment 31, the cellulose ethanoate propionic ester film (T-2) of the thickness 40 μ m that make among the cellulosic triacetate film (T-1) of the thickness 80 μ m that make among the applying embodiment 13 on light polarizing film and the embodiment 17 is made polarizer 1, polarizer 2 as the another side that is fitted in LCD panel, utilized the mode such as above-mentioned making polarizer 1, be configured so that its applying direction is symmetrical centered by liquid crystal.

Thereby as shown in table 2, the film T-3 of polarizer 2 is the cellulose ethanoate propionic ester film of the thickness 40 μ m of making among the embodiment 17, and the film T-4 of polarizer 2 is the cellulosic triacetate film of the thickness 80 μ m of making among the embodiment 13.

For the LCD panel of the embodiment 28～31 of such gained, as embodiment 27, measure its contrast, shown in the acquired results table 2 described as follows.

Comparative example 11

In order to compare, as above-described embodiment 27, made LCD panel, with the difference of above-described embodiment 27 be: the cellulose ethanoate propionic ester film (T-2) of the thickness 80 μ m that make in the cellulosic triacetate film (T-1) of the thickness 80 μ m that make in the applying comparative example 2 on light polarizing film and the comparative example 8 is made polarizer 1, polarizer 2 as the another side that is fitted in LCD panel, utilized the mode such as above-mentioned making polarizer 1, be configured so that its applying direction is symmetrical centered by liquid crystal.

Thereby as shown in table 2, the film T-3 of polarizer 2 is the cellulose ethanoate propionic ester film of the thickness 80 μ m of making in the comparative example 8, and the film T-4 of polarizer 2 is the cellulosic triacetate film of the thickness 80 μ m of making in the comparative example 2.

For the LCD panel of the comparative example 11 that obtains like this, as embodiment 27, measure its contrast, shown in the acquired results table 2 described as follows.

[table 2]

By the result of above-mentioned table 2 as can be known: the LCD panel of embodiments of the invention 27～31 has the contrast than the LCD panel excellence of comparative example 11.

Claims (8)

1. the manufacture method of a cellulose ester membrane, the method comprises, the resin solution curtain coating that will comprise cellulose ester resin forms casting films at casting support, and the solvent in the casting films is carried out drying until casting films reaches strippable state, after casting films is peeled off from casting support, control the both ends of the sheet stock that strips down, stretch at width, through behind this stretching process, dry solvent, and reel, thereby obtain cellulose ester membrane; Wherein,

The extensibility of sheet stock is 20～60% in the stretching process, and for the glass transition temperature Tg of the film after reeling, and the temperature of the hot blast that blows out from the hot blasting device in the stretching process is Tg+35 ℃～Tg+80 ℃,

The residual solvent amount that is about to enter the film before the stretching process is 10～35 quality %.

2. the manufacture method of the cellulose ester membrane of claim 1 wherein, has and removes the device of removing that desolventizes organic principle in addition contained from the exhaust wind that stretching process is sent here.

3. the manufacture method of the cellulose ester membrane of claim 2 wherein, is recycled the exhaust wind of having removed described organic principle again as the part of the dry wind of stretching process upstream.

4. the manufacture method of the cellulose ester membrane of claim 3, wherein, the described device of removing is a plurality of continuous.

5. cellulose ester membrane, it is to adopt the cellulose ester membrane that each method is made in the claim 1～2, wherein, the width of the film behind the coiling is 1650～2500mm.

6. the cellulose ester membrane of claim 5, wherein, the thickness of the film behind the coiling is 40～80 μ m.

7. a polarizer has used the cellulose ester membrane of claim 5 or 6 in its one side.

8. display unit, it has used the cellulose ester membrane of claim 5 or 6.

Images