JP2003171499A - Cellulose ester film, and polarizing plate and liquid crystal display each using the film and method for producing the cellulose ester film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cellulose ester film having sufficient durability and decreased in causing bleed-out. <P>SOLUTION: This cellulose ester film is obtained by containing a polyester as a component and containing a polyurethane resin having ≥100,000 weight- average molecular weight. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a cellulose ester film, a polarizing plate and a liquid crystal display device using the cellulose ester film, and a method for producing the cellulose ester film.

[0002]

2. Description of the Related Art Cellulose ester films are preferably used in silver halide photographic light-sensitive materials and liquid crystal image display devices because of their transparency and characteristics without optical defects. In particular, it is used as a protective film for polarizing plates in liquid crystal image display devices.

In recent years, in information equipments equipped with a liquid crystal image display device such as a notebook personal computer, a car navigation system, and a mobile phone, development for thinning has been advanced, and protection for a polarizing plate used in the liquid crystal image display device has been advanced. The film is also required to be thin. Therefore, the cellulose ester film is also thinned.

However, when the cellulose ester film is thinned, the tear strength is lowered and the durability is lowered.

As a countermeasure against this, Japanese Patent Publication No. 47-760
Japanese Patent Publication No. 44-32672 discloses a technique of increasing the tear strength by incorporating a polyurethane resin containing polyester as a component into a cellulose ester film.

[0006]

In a polarizing plate protective film or the like of a liquid crystal display device, durability of the polarizing plate protective film is also required, but it is important that the liquid crystal screen and the like are sufficiently easy to see. , Sufficient transparency, retention, flatness, etc. are required. Furthermore, it is required that the viewing angle dependence is small.

In addition, in a cellulose ester film containing a polyurethane resin containing polyester as a component, the ester bond portion of the polyester in the polyurethane resin is hydrolyzed with the passage of time, which causes the surface of the cellulose ester film to turn white and cloudy. There is a problem that (bleed-out) occurs, and the visibility of a liquid crystal display screen or the like may be reduced.

The present invention has been made in view of the above problems, and a first object of the present invention is to provide a cellulose ester film having sufficient durability and reducing the occurrence of bleed-out. is there.

A second object of the present invention is to provide a highly transparent cellulose ester film.

The third object of the present invention is to provide a cellulose ester film having a small holding property.

A fourth object of the present invention is to provide a cellulose ester film with little color turbidity in an IPS type liquid crystal display device.

A fifth object of the present invention is to provide a cellulose ester film having high flatness.

A sixth object of the present invention is to provide a polarizing plate and a liquid crystal display device using a cellulose ester film which achieves at least one of the above objects, and a method for producing the cellulose ester film.

The present invention achieves at least one of the above objects.

[0015]

The above object was achieved by the following constitution.

(1) Having polyester as a component,
A cellulose ester film containing a urethane resin having a weight average molecular weight of 100,000 or more.

(2) A cellulose ester film containing a urethane resin having polyester as a component and an antioxidant.

(3) A cellulose ester film containing a urethane resin having polyester as a component and a plasticizer.

(4) The cellulose ester film according to (2) or (3), wherein the urethane resin has a weight average molecular weight of 100,000 or more.

(5) The cellulose ester film as described in (3) or (4), which contains an antioxidant.

(6) The cellulose ester film according to any one of (1) to (5), which contains the urethane resin in an amount of 1 to 30% by mass.

(7) The cellulose ester film according to any one of (1) to (6), wherein the urethane resin is composed of polyester and toluene diisocyanate.

(8) The cellulose ester film according to any one of (1) to (6), wherein the urethane resin is synthesized from polyester and p, p'-diphenylmethane diisocyanate. .

(9) The cellulose ester film according to any one of (1) to (8), wherein the polyester is synthesized with adipic acid and ethylene glycol.

(10) The cellulose ester film according to any one of (1) to (9), wherein the urethane group concentration of the urethane resin is 0.3 to 1.50 mmol / g.

(11) Haze value is 0.01 to 0.2%
Any one of (1) to (10), characterized in that
Item 7. A cellulose ester film according to item.

(12) Any one of (1) to (11), characterized in that the tear strength by the Elmendle method when converted to a thickness of 40 μm is 0.05 N or more.
Item 7. A cellulose ester film according to item.

(13) Any one of (1) to (12)
A polarizing plate having the cellulose ester film according to the item.

(14) Any one of (1) to (12)
A liquid crystal display device comprising the cellulose ester film according to item.

(15) Using the solution casting film forming method (1)
(12) A method for producing a cellulose ester film, which comprises producing the cellulose ester film according to any one of (12).

The present invention will be described in more detail below. The present inventor has found that when a urethane resin having polyester as a component and having a weight average molecular weight of 100,000 or more is contained in the cellulose ester film, bleed-out of the cellulose ester film is less likely to occur.

The present inventor has also found that bleeding out of the cellulose ester film is less likely to occur by incorporating a urethane resin having polyester as a component and an antioxidant into the cellulose ester film. At this time, it was also found that it is preferable that the weight average molecular weight of the urethane resin to be contained is 100,000 or more, because bleeding out of the cellulose ester is further difficult to occur.

Furthermore, the present inventor has also found that bleeding out of the cellulose ester film is less likely to occur by incorporating a urethane resin having polyester as a component and a plasticizer into the cellulose ester film. At this time, it was also found that it is preferable that the weight average molecular weight of the urethane resin to be contained is 100,000 or more, because the cellulose ester film is more unlikely to bleed out. Furthermore, they have found that the inclusion of an antioxidant is particularly preferable because bleed-out is further suppressed.

The cellulose ester film of the present invention comprises
It is more preferable that the weight average molecular weight of the urethane resin is 200,000 or more, which makes bleeding out more difficult.

Since the cellulose ester film of the present invention contains a urethane resin, it has high tear strength and excellent durability.

The material of the urethane resin used in the cellulose ester film of the present invention is not particularly limited as long as it can increase the tear strength and durability by containing it, but the polyester and toluene diisocyanate react with each other. It is preferable that the synthetic urethane resin is used. By using this urethane resin, the tear strength becomes even higher and bleed-out can be further suppressed.
In addition, the transparency can be increased. Furthermore, the moisture permeability can be suppressed.

Even if a urethane resin synthesized by reacting polyester with p, p'-diphenylmethane diisocyanate is used as the urethane resin, the tear strength is further increased and the bleed-out can be further suppressed. The transparency can be increased. Furthermore, the moisture permeability can be suppressed.

Further, the polyester used for the urethane resin is preferably synthesized from adipic acid and ethylene glycol. As a result, the tear strength is further increased, bleed-out can be further suppressed, and the transparency can be further increased.

The urethane group concentration of the urethane resin contained in the cellulose ester film of the present invention is 0.3 to 1.
It is preferably 50 mmol / g, and 0.7 to 1.
It is more preferably 20 mmol / g, whereby the tear strength is increased and the transparency is also increased. The urethane group concentration is NMR (JEOL Ltd .: Lambda40
It can be measured in 0).

The cellulose ester film of the present invention comprises
The urethane resin content is preferably 1 to 30% by mass, more preferably 15 to 25% by mass. As a result, the tear strength is further increased, bleed-out can be further suppressed, and the transparency can be increased.

Examples of the plasticizer contained in at least one of the cellulose ester films of the present invention include alkylphthalylalkyl glycolates, phosphoric acid esters and carboxylic acid esters.

Examples of the alkylphthalylalkyl glycolates include methylphthalylmethyl glycolate,
Ethyl phthalyl ethyl glycolate, propyl phthalyl propyl glycolate, butyl phthalyl butyl glycolate, octyl phthalyl octyl glycolate, methyl phthalyl ethyl glycolate, ethyl phthalyl methyl glycolate, ethyl phthalyl propyl glycolate, propyl Phthalyl ethyl glycolate, methyl phthalyl propyl glycolate, methyl phthalyl butyl glycolate, ethyl phthalyl butyl glycolate, butyl phthalyl methyl glycolate, butyl phthalyl ethyl glycolate, propyl phthalyl butyl glycolate, butyl phthali Rupropyl glycolate, methyl phthalyl octyl glycolate, ethyl phthalyl octyl glycolate,
Examples thereof include octylphthalylmethyl glycolate and octylphthalylethyl glycolate. Examples of the phosphoric acid ester include triphenyl phosphate, tricresyl phosphate, phenyldiphenyl phosphate and the like. Examples of the carboxylic acid ester include phthalic acid ester and citric acid ester,
Examples of the phthalic acid ester include dimethyl phthalate, diethyl phosphate, dioctyl phthalate and diethylhexyl phthalate, and examples of the citric acid ester include acetyl triethyl citrate and acetyl tributyl citrate. Other examples include butyl oleate, methylacetyl ricinoleate, dibutyl sebacate, and triacetin.

Among them, methylphthalylmethylglycolate, ethylphthalylethylglycolate, propylphthalylpropylglycolate, butylphthalylbutylglycolate and octylphthalyloctylglycolate are preferable, and ethylphthalylethylglycolate is particularly preferable. It is preferably used. Also, two or more of these alkylphthalylalkyl glycolates may be mixed and used.

The cellulose ester film of the present invention comprises
The amount of plasticizer contained is 1 with respect to the cellulose ester.
-30 mass% is preferable, and especially 4-13 mass% is preferable. By setting it in this range, the durability can be improved while maintaining the retaining property of the cellulose ester film.

The antioxidant contained in at least one of the cellulose ester films of the present invention is specifically a phenylenediamine antioxidant (manufactured by Ouchi Shinko Chemical Industry Co., Ltd .: Nocrac CD, Nocrac TO, Nocrac). GI, Aspic), imidazole-based antioxidants (Ouchi Shinko Chemical Co., Ltd .: Nocrac MB, Nocrac MMB, etc.), hindered phenolic anti-oxidants (BH
T, etc.), and dithiocarbamate anti-aging agents. Preferably di-t-butylmethylphenol (B
HT).

The cellulose ester film of the present invention contains a cellulose ester, and examples of the cellulose ester include cellulose triacetate, cellulose diacetate, cellulose ester propionate and cellulose propionate. It may be one containing an acyl group having 4 or more carbon atoms such as cellulose acetate butyrate and cellulose acetate propionate butyrate. Among them, those having only an acyl group having 2 to 3 carbon atoms are preferable, and cellulose triacetate and cellulose acetate propionate are particularly preferable. The substitution degree of the acyl group is preferably 2.6 to 3.0. By setting the substitution degree within this range, a film having good durability can be obtained. If the substitution degree of the acetyl group is too small, the breaking strength of the film may be too low, so that the substitution degree is preferably 1.4 or more. The method for measuring the substitution degree of the acyl group is ASTM-D817.
It can be measured by -96.

The cellulose ester used in the present invention can be synthesized by a usual method. For example, JP-A-1
It can be synthesized by the method described in 0-45804.

The cellulose as the raw material of the cellulose ester is not particularly limited, but cotton linter, wood pulp, kenaf and the like can be mentioned. The cellulose esters obtained from them can be mixed and used in arbitrary proportions. Cellulose ester obtained from cotton linter is preferable because it has particularly good releasability from the support during film formation.

The weight average molecular weight of the cellulose ester used in the present invention is preferably in the range of 70,000 to 300,000 because of high mechanical strength when molded. 8 more
20,000 to 200,000 is preferable.

The cellulose ester film of the present invention comprises
For example, when it is used in a liquid crystal display device, it is often used outdoors, and it is also important to add a function of blocking ultraviolet rays to a protective film for a polarizing plate. For this purpose, it is preferable to contain an ultraviolet absorber, and the ultraviolet absorber used preferably has no absorption in the visible light region, and examples thereof include a benzotriazole compound, a benzophenone compound, and a salicylic acid compound. For example, 2- (2'-hydroxy-5-methylphenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5'-di-t-butylphenyl) benzotriazole, 2- (2'-hydroxy- 3'-di-t-butyl-5'-methylphenyl) benzotriazole, 2,
4-dihydroxybenzophenone, 2-hydroxy-4
-Methoxybenzophenone, 2-hydroxy-4-n-
Octoxybenzophenone, 4-dodecyloxy-2-
Examples are hydroxybenzophenone, 2,2 ', 4,4'-tetrahydroxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, phenyl salicylate and methyl salicylate.

The amount of the ultraviolet absorber added is preferably in the range of 0.5 to 20% by mass with respect to the cellulose ester,
The range of 0.6 to 5 mass% is more preferable.

For the purpose of improving the heat and moisture resistance of the film,
A hindered phenol compound is preferably used,
2,6-di-t-butyl-p-cresol, pentaerythrityl-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-diethylenebis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], octadecyl-3- (3,3
5-di-t-butyl-4-hydroxyphenyl) propionate, N, N'-hexamethylenebis (3,5-di-t-butyl-4-hydroxy-hydrocinnamamide), 1,3,5- Trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl)
Examples thereof include benzene and tris- (3,5-di-t-butyl-4-hydroxybenzyl) -isocyanurate. In particular 2,6-di-t-butyl-p-cresol, pentaerythrityl-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-t). A phosphorus-based processing stabilizer such as -butylphenyl) phosphite may be used in combination. The addition amount of these compounds is preferably 1 ppm to 1.0% by mass with respect to the cellulose ester, and 1
0 to 1,000 ppm is more preferable. Also, besides this,
A heat stabilizer such as a salt of an alkaline earth metal such as calcium or magnesium may be added.

A dye may be added to the cellulose ester film of the present invention for the purpose of improving the yellowness of the film. The color tone is preferably such that it can be colored in gray as seen in ordinary photographic supports. However, unlike a photographic support, it is not necessary to prevent light piping, so the content may be small, and the mass ratio to cellulose ester is preferably 1 to 100 ppm, and 2 ppm to 50 p.
pm is more preferred. Since the cellulose ester has a slight yellow tint, a blue or purple dye is preferably used. A plurality of dyes may be appropriately combined to give a gray color.

If the films are not slippery, the films may block each other, resulting in poor handleability. In this case, inorganic fine particles such as silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, kaolin, talc, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate, and calcium phosphate, and high crosslinking degree. It is preferable to include a matting agent such as molecules. Of these, silicon dioxide is preferable because it can reduce the haze of the film. The matting agent is preferably blended so that the haze of the film is 0.6% or less and the dynamic friction coefficient is 0.5 or less. The matting agent used for this purpose has an average particle size of 0.01 to 1.0 μm,
Content is 0.005 to cellulose ester
0.3 mass% is preferable.

In addition to the above, antistatic agents, flame retardants, lubricants, oils and the like may be added as appropriate. The cellulose ester film of the present invention has a haze value of 0.01 to, considering its use as a protective film for polarizing plates of liquid crystal display devices and the like.
It is preferably 0.2%. This makes it easier to see the liquid crystal display device. The haze value is TURBIDITY METER T- manufactured by Tokyo Denshoku Co., Ltd.
It can be measured with a commercially available measuring instrument such as 2600 DA.

The cellulose ester film of the present invention comprises
Considering the use as a protective film for a polarizing plate of a liquid crystal display device or the like, it is necessary to have a certain strength or more to improve durability in order to make it thinner, so that the film thickness is 40 μm. It is preferable that the tear strength by the Elmendle method when converted into the thickness of 0.05 N is 0.05 N or more. Here, a tear strength of 0.05 N or more measured by the Elmendle method when converted to a film thickness of 40 μm means JI
As described in SK7128-1991, the thickness is 40 μm by using the B method such as the A method (trouser tear method), the B method (Elemendorf tear method), and the C method (right angle tear method).
The value measured using a film with a thickness of m is 0.05 N
The above is shown.

The cellulose ester film of the present invention comprises
Considering the use as a protective film for a polarizing plate of a liquid crystal display device or the like, it is preferable that the moisture permeability is 300 g / m ² · 24 hr or less. As a result, it is possible to suppress the entry of water vapor from the polarizing plate and improve the durability of the liquid crystal display device. The moisture permeability is JIS Z0208-
According to 76, it is a value measured under the conditions of 25 ° C. and 90% RH.

The cellulose acetate film of the present invention comprises
Since it has the above-mentioned properties, it is useful as a protective film for a polarizing plate, and particularly useful as a protective film for a polarizing plate of a liquid crystal display device.

The cellulose ester film of the present invention comprises
It is preferably produced by using a solution casting film forming method. As a result, a cellulose ester film having more excellent flatness can be obtained, and the visibility of a liquid crystal display device or the like can be improved.

A method for producing a cellulose ester film by the solution casting film forming method according to the present invention will be described.

The solution casting film forming method has a dissolving step, a casting step, a solvent evaporation step, a peeling step, a drying step and a winding step.

Dissolution step: a step of dissolving the flakes in an organic solvent mainly containing a good solvent for the flakes of cellulose ester in a dissolution vessel while stirring to form a dope.

The dissolution method useful in the present invention is carried out at a temperature not lower than the boiling point of the main solvent and under a pressure at which it does not boil (hereinafter referred to as a high temperature dissolution method), and the cellulose ester and the organic solvent are -100 ° C to -10. Or by mixing the cellulose ester with an organic solvent of -100 ° C to -10 ° C and then heating to 0 ° C to 120 ° C (hereinafter referred to as a cooling dissolution method), the cellulose ester and the organic solvent. 50 bar ~
A method of pressurizing to 2,000 atm (hereinafter referred to as high pressure dissolution method) can be mentioned.

In the high temperature dissolution method, for example, when methyl acetate (boiling point 56.32 ° C.) is used as the main solvent, the temperature is preferably 56.32 ° C. to 120 ° C.
0 ° C to 90 ° C is preferable. At this time, the pressure at which boiling does not occur may be about 2 atm or more, and there is no particular upper limit, but the effect is saturated at about 50 atm, so 2 to 50 atm is preferable. 2 to 10
Atmospheric pressure is preferred.

For the cellulose ester, when the acetyl group substitution degree is 2.5 or more, it is preferable to use the cooling dissolution method or the high pressure dissolution method.

The cooling dissolution method is described in JP-A-9-955.
No. 38, No. 9-95544 and No. 9-95557, the method of forming a dope using a solvent such as acetone, methyl acetate, ethyl formate, etc. can be used.

Regarding the high pressure dissolution method, JP-A-11-21
The high pressure dissolution method described in Japanese Patent No. 379 can be used. In the publication, acetone is used as the organic solvent, but methyl acetate can also be used.

For the cellulose ester dope, 0.1 to
It is preferable to contain 30% by mass of an alcohol having 1 to 4 carbon atoms. As a result, after casting the dope onto the casting support, the solvent begins to evaporate and the alcohol content increases, and the web (dope film) gels, making the web strong and easy to peel from the casting support. In addition, the effect of promoting the dissolution of the cellulose ester of the chlorine-free organic solvent can be obtained. As the alcohol having 1 to 4 carbon atoms,
Methanol, ethanol, n-propanol, iso-
Propanol, n-butanol, sec-butanol,
Mention may be made of tert-butanol. Of these, ethanol is most preferable because it is stable, has a relatively low boiling point, has good drying properties, and has no toxicity.

The solid content concentration of the dope is usually preferably 10 to 40% by mass, and the dope viscosity is preferably adjusted in the range of 100 to 500 poise in order to obtain good film flatness.

The dope prepared as described above is filtered with a filter medium, defoamed, and sent to the next step by a pump.

Casting process: The dope is sent to a pressurizing die through a pressurizing type quantitative gear pump, and at a casting position, an endless metal belt for endless transfer or a casting support for a rotating metal drum (hereinafter, simply referred to as a casting support). It is a step of casting the dope from a pressure die onto a support. The surface of the casting support is a mirror surface. Other casting methods include a doctor blade method for adjusting the film thickness of a cast dope film with a blade, or a method with a reverse roll coater for adjusting with a reverse rotating roll.
It is preferable to use a pressure die that can adjust the slit shape of the die and can easily make the film thickness uniform. The pressure die includes a coat hanger die and a T die, and any of them is preferably used.
A pressure die is placed on the casting support to increase the film forming speed.
It is also possible to provide more than one base and divide the doping amount to form multiple layers.

Solvent evaporation step: a step of heating a web (the dope film is called a web after casting the dope on the casting support) to evaporate the solvent by heating on the casting support. . To evaporate the solvent, there are a method of blowing air from the web side and / or a method of transferring heat from the back surface of the support by a liquid, a method of transferring heat from the front and back sides by radiant heat, and the like. Drying efficiency is good and preferable.
A method of combining them is also preferable.

Peeling step: This is a step of peeling the web having the solvent evaporated on the support at the peeling position. The peeled web is sent to the next step. If the residual solvent amount (the following formula) of the web at the time of peeling is too large, peeling may be difficult, or conversely, if the web is sufficiently dried on the support and then peeled off, a part of the web may peel off.

As a method of increasing the film-forming speed (the film-forming speed can be increased because the film is peeled off while the amount of residual solvent is as large as possible), there is a gel casting method (gel casting) in which the amount of residual solvent can be peeled off. . There are a method in which a poor solvent for cellulose ester is added to the dope and gelling is performed after the dope is cast, and a method in which the temperature of the support is lowered to cause gelation. There is also a method of adding a metal salt to the dope. By peeling on the support and strengthening the film, the peeling can be accelerated and the film forming speed can be increased. When peeling at a time when the amount of residual solvent is larger, if the web is too soft, the flatness at the time of peeling may be impaired, and cracks and vertical streaks due to peeling tension are likely to occur, and the amount of peeling residual solvent is determined by the balance between economic speed and quality. Can be decided

Drying step: a step of drying the web by using a drying device that alternately conveys the web through rolls arranged in a staggered manner and / or a tenter device that clips both ends of the web with clips and conveys the web. As a drying means, hot air is generally blown on both sides of the web, but a microwave may be applied instead of the air to heat the web. Drying too rapidly tends to impair the flatness of the finished film. Drying at a high temperature is preferably carried out when the residual solvent is about 8% by mass or less. In general, the drying temperature is usually 40 to 250 ° C, preferably 70 to 180 ° C. The drying temperature, the amount of drying air and the drying time vary depending on the solvent used, and the drying conditions may be appropriately selected depending on the type and combination of the solvents used.

In the drying step after peeling from the surface of the casting support, the web tends to shrink in the width direction due to the evaporation of the solvent. Shrinkage increases with rapid drying at high temperature. Drying while suppressing this shrinkage as much as possible is preferable for improving the flatness of the finished film. From this viewpoint, for example, Japanese Patent Laid-Open No. 62-4662.
It is preferable to use a method (tenter method) in which all the drying steps or a part of the drying steps as described in Japanese Patent Laid-Open No. 5 are dried while holding the width ends of the web with clips in the width direction.

Winding step: The web has a residual solvent content of 2
This is a step of winding the film as a film after the content becomes less than or equal to mass%. By setting the residual solvent amount to 0.4% by mass or less, a film having good dimensional stability can be obtained. As a winding method, a generally used one may be used, and there are a constant torque method, a constant tension method, a taper tension method, a program tension control method with a constant internal stress, and the like, and these may be used properly.

The amount of residual solvent can be represented by the following formula. Residual solvent amount (mass%) = {(M−N) / N} × 100 where M is the mass of the web at any time and N is M
It is the mass when dried at 0 ° C. for 3 hours.

The thickness of the cellulose ester film can be controlled by adjusting the dope concentration, the amount of liquid pumped, the die slit gap, the die extrusion pressure, and the casting support so as to obtain a desired thickness. It is better to control the speed etc. Further, as means for making the film thickness uniform, it is preferable to use a film thickness detecting means to feed back the programmed feedback information to the above-mentioned respective devices for adjustment.

In the steps from immediately after casting through the solution casting method to drying, the atmosphere in the drying device may be air, but it is performed in an inert gas atmosphere such as nitrogen gas or carbon dioxide gas. May be.

[0081]

The present invention will be described in detail below with reference to examples, but the present invention is not limited thereto. 1. Production of Film Samples 1 to 23 <Film Samples 1 to 20> A dope composition 1 having the following composition was placed in a sealed container, heated to 70 ° C., and stirred.
Cellulose triacetate (TAC) was completely dissolved to obtain a dope. The time required for dissolution was 4 hours. The dope composition was filtered and then uniformly cast on a stainless band support at 22 ° C. at a dope temperature of 35 ° C. using a belt casting device. The temperature of the stainless steel band support was 20 ° C.

Then, after drying to a peelable range, the dope was peeled from the stainless band support.
At this time, the amount of residual solvent in the dope was 25%. The time required from casting the dope to peeling was 3 minutes. After peeling from the stainless steel band support, it was dried at 120 ° C while holding it in the width direction, then released from the width holding, and dried in a drying zone at 120 ° C and 135 ° C while being conveyed by a number of rolls. A knurling process with a width of 10 mm and a height of 5 μm was applied to both ends of the film to prepare a cellulose triacetate film sample 1 having a film thickness of 40 μm. The film width of the film sample was 1300 mm and the winding length was 3000 m. Take-up tension is 1.5N initial tension
/ 1300 mm, and the final winding tension was 1 N / 1300 mm. Film samples 2 to 20 were prepared for the dope compositions 2 to 20 in the same manner. In this way, film samples 1 to 20 were obtained. [Dope Compositions 1 to 20] Triacetyl cellulose (acetylation degree 61.0%) 100 parts by mass 2- (2'-hydroxy-3 ', 5'-di-t-butylphenyl) bezotriazole 2 parts by mass Urethane resin described in Table 1 below 20 parts by mass Plasticizer described in table 1 below 5 parts by mass Antioxidant described in table 1 below 0.5 parts by mass Methylene chloride 475 parts by mass Ethanol 50 parts by mass

[0083]

[Table 1]

<Film Sample 21> A film sample 21 was prepared in the same manner as the film sample 1 except that the dope composition 1 was changed to the following dope composition 21 in the preparation of the film sample 1. [Dope composition 21] Triacetyl cellulose (acetylation degree 61.0%) 100 parts by mass 2- (2'-hydroxy-3 ', 5'-di-t-butylphenyl) bezotriazole 1 part by mass Triphenyl Phosphate 15 parts by weight Methylene chloride 475 parts by weight Ethanol 50 parts by weight <Film sample 22> Film sample 22 was prepared in the same manner as in film sample 1 except that dope composition 1 was replaced with dope composition 22 below. It was made. [Dope composition 22] Triacetyl cellulose (acetylation degree 61.0%) 100 parts by mass 2- (2'-hydroxy-3 ', 5'-di-t-butylphenyl) bezotriazole 1 part by mass Ethylphthali Ruethyl glycolate 4 parts by mass Methylene chloride 475 parts by mass Ethanol 50 parts by mass <Film sample 23> Film sample was prepared in the same manner except that dope composition 1 was changed to dope composition 23 below in the preparation of film sample 1. 23 was produced. [Dope composition 23] Triacetyl cellulose (acetylation degree 61.0%) 100 parts by mass 2- (2'-hydroxy-3 ', 5'-di-t-butylphenyl) bezotriazole 1 part by mass Triphenyl Phosphate 10 parts by mass Laurylbenzene sulfonate 2 parts by mass Methylene chloride 475 parts by mass Ethanol 50 parts by mass 2. Production of Polarizing Plate Samples 1 to 23 Film sample 1 was alkali-treated with a 2.5 M aqueous sodium hydroxide solution at 40 ° C. for 60 seconds and washed with water for 3 minutes to form a saponification-treated layer to obtain an alkali-treated film.

Next, a polyvinyl alcohol film having a thickness of 120 μm was immersed in 100 parts by mass of an aqueous solution containing 1 part by mass of iodine and 4 parts by mass of boric acid, and stretched 4 times at 50 ° C. to form a polarizing film. A polarizing plate sample 1 was prepared by laminating the alkali-treated film on both surfaces of this polarizing film with a fully saponified polyvinyl alcohol 5% aqueous solution as an adhesive. With respect to the film samples 2 to 23, polarizing plate samples 2 to 23 were prepared by the same method as described above. 3. Evaluation of Film Samples 1 to 23 and Polarizing Plate Samples 1 to 23 The following (1) to (6) were evaluated for the film samples 1 to 23 and the following (7) was evaluated for the polarizing plate samples 1 to 23. (1) TURBIDITY METER manufactured by Hayes Tokyo Denshoku Co., Ltd.
The haze value was measured using T-2600DA. (2) Tear strength The tearing load of the Elmendorf method is specified in JIS K 712.
The tear strength was measured by a light load tearing device manufactured by Toyo Seiki Co., Ltd. in accordance with 8-1991. (3) Moisture Permeability The moisture permeability of each film sample was measured according to the method described in JIS Z 0208. The temperature and humidity conditions tested were 2
It is 5 ° C. and 90% RH. (4) Retention (Plasticizer Precipitation) A film sample was set to 10 cm in the width direction and 10 in the longitudinal direction.
Cut out the sample in the size of cm, 23 ℃, 55% RH
After measuring the mass after standing for 24 hours at 80 ℃, 90%
It was treated under RH conditions for 48 hours. Further, the treated film sample was allowed to stand for 24 hours at 23 ° C. and 55% RH for 24 hours, and the mass was measured to calculate the retention property by the following method.

Retention property = (mass before treatment−mass after treatment)
/ Mass before processing × 100% (5) Bleed-out value A film sample is 10 cm in the width direction and 10 in the longitudinal direction.
Cut out the sample in the size of cm, 80 ℃, 90% RH
Under the conditions of 48 hours, then TUR manufactured by Tokyo Denshoku Co., Ltd.
The haze value measured using BIDITY METER T-2600DA was made into the bleed-out value. (6) Retardation value (Rt value) An automatic birefringence meter KOBRA-21AH (manufactured by Oji Scientific Instruments) was used to measure the film sample at 23 ° C and 55%.
Under the condition of RH, the three-dimensional refractive index is measured at a wavelength of 590 nm, and the refractive indices Nx, Ny and Nz are obtained.

The retardation value Rt in the thickness direction was calculated according to the following formula. Rt = {(Nx + Ny) / 2−Nz} * d, where Nx is the refractive index of the film in the direction parallel to the film forming direction, Ny is the refractive index of the film in the direction perpendicular to the film forming direction, Nz represents the refractive index of the film in the thickness direction of the film, and d represents the thickness (nm) of the film. (7) Polarizing plate durability test Two 10 cm × 10 cm polarizing plate samples were subjected to high temperature and high humidity treatment (conditions: 80 ° C.-90% RH, 50 hours), and the surface condition was observed.

⊚: Less than 5% of the part where the polarizing plate surface was clouded by bleed-out (a level that does not pose a problem as a polarizing plate) ◯: 5% or more and less than 10% of the part where the polarizing plate surface was clouded by bleed-out (as a polarizing plate No problem) Δ: 10% or more and less than 20% of the part where the polarizing plate surface is clouded by bleed-out (a level that can be used as a polarizing plate) ×: 20% or more of the part where the polarizing plate surface is clouded by bleed-out (the polarizing plate) There is no problem in practical use if it is Δ or above.

The results are shown in Tables 2 and 3.

[0090]

[Table 2]

[0091]

[Table 3]

For polarizing plate samples 3 and 22, I
It was incorporated into a PS module and evaluated for color. The results are shown in Table 4.

[0093]

[Table 4]

From the results shown in Tables 2 and 3, the film sample of the present invention has a very high haze of 0.1%, and therefore is very useful particularly when used as a polarizing plate of a liquid crystal display device. It turned out that

Further, since the film sample of the present invention has high tear strength and high durability, it was found to be very useful particularly when used for a polarizing plate of a liquid crystal display device.

Further, since the film sample of the present invention has a small holding property, it was found to be very useful particularly when used for a polarizing plate of a liquid crystal display device.

Further, since the film sample of the present invention has a low water vapor transmission rate, when it is used particularly as a polarizing plate of a liquid crystal display device, it is possible to prevent deterioration of the function of the liquid crystal display device due to invasion of water vapor. , Found that the durability can be improved.

Furthermore, since the film sample of the present invention suppresses the occurrence of bleed-out, it was found to be very useful especially when used as a polarizing plate of a liquid crystal display device.

Furthermore, the polarizing plate sample 3 of the present invention is particularly
It was found that t is small, and when it is used for a polarizing plate of an IPS liquid crystal display device, color turbidity is suppressed and it is very useful.

Further, since the film sample of the present invention is manufactured by using the solution casting film forming method, it has high flatness,
It is very useful when used as a polarizing plate protective film of a liquid crystal display device.

Further, since the polarizing plate sample of the present invention can suppress the occurrence of bleed-out, it was found that it is very useful when used as a polarizing plate protective film of a liquid crystal display device.

Furthermore, each of the polarizing plate samples of the present invention was set in a liquid crystal display device and used, and it was confirmed that they were very useful due to the above-mentioned effects.

[0103]

By at least one of the cellulose ester films of the present invention, it is possible to provide a cellulose ester film having sufficient durability and reducing the occurrence of bleed-out.

At least one of the cellulose ester films of the present invention could provide a highly transparent cellulose ester film.

At least one of the cellulose ester films of the present invention could provide a cellulose ester film having a small retention property.

At least one of the cellulose ester films of the present invention can provide a cellulose ester film with little color turbidity in the IPS type liquid crystal display device.

At least one of the cellulose ester films of the present invention could provide a cellulose ester film having high flatness.

It was possible to provide a polarizing plate and a liquid crystal display device using the cellulose ester film of the present invention having at least one of the above effects, and a method for producing the cellulose ester film.

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 2H049 BA02 BB23 BB24 BB33 BC09                       BC22                 2H091 FA08X FA08Z FB02 GA16                       LA30                 4F071 AA09 AA53 AA81 AC10 AC11                       AC12 AF16Y AF30Y AH16                       BB02 BC01 BC12                 4J002 AB021 CK032 EH146 EJ017                       EJ027 EN077 EU117 EV147                       EW046 FD026 FD077 GQ00                       GS00

Claims (15)

[Claims] 1. A cellulose ester film containing a polyester as a component and a urethane resin having a weight average molecular weight of 100,000 or more. 2. A cellulose ester film containing a urethane resin having polyester as a component and an antioxidant. 3. A cellulose ester film containing a urethane resin having polyester as a component and a plasticizer. 4. The weight average molecular weight of the urethane resin is 1
It is 00000 or more, The claim 2 or 3 characterized by the above-mentioned.
The cellulose ester film according to. 5. The cellulose ester film according to claim 3, which further comprises an antioxidant. 6. The cellulose ester film according to claim 1, containing 1 to 30% by mass of the urethane resin. 7. The cellulose ester film according to claim 1, wherein the urethane resin is composed of polyester and toluene diisocyanate. 8. The urethane resin is polyester and p,
It is synthesize | combined with p'-diphenylmethane diisocyanate, The cellulose-ester film of any one of Claims 1-6 characterized by the above-mentioned. 9. The cellulose ester film according to claim 1, wherein the polyester is synthesized with adipic acid and ethylene glycol. 10. The cellulose ester film according to claim 1, wherein the urethane group concentration of the urethane resin is 0.3 to 1.50 mmol / g. 11. The cellulose ester film according to claim 1, having a haze value of 0.01 to 0.2%. 12. The cellulose ester film according to claim 1, which has a tear strength of 0.05 N or more according to the Elmendle method when converted into a thickness of 40 μm. 13. A polarizing plate having the cellulose ester film according to claim 1. 14. A liquid crystal display device comprising the cellulose ester film according to claim 1. 15. The method according to claim 1, which uses a solution casting film forming method.
3. A method for producing a cellulose ester film, comprising producing the cellulose ester film according to any one of 2 above.