JPWO2015098491A1 - Cellulose ester film, method for producing the same, and polarizing plate - Google Patents

Abstract

An object of the present invention is to provide a cellulose ester film having excellent adhesiveness with both PVA water paste and UV curable adhesive in adhesion to a polarizer, and having a thin film and excellent retardation, and a method for producing the same And providing a polarizing plate. The cellulose ester film of the present invention is a cellulose ester film containing at least a cellulose acetate (resin A) having a degree of acetyl group substitution in the range of 2.1 to 2.6 and a retardation increasing agent, The contact angle of pure water on the surface of the cellulose ester film is in the range of 30 to 75 °, and the standard deviation when the contact angle is measured at 20 points at equal intervals in the width direction of the film is 0.05 to 3. It is characterized by being within a range of 0 ° and having a light transmittance of 80% or more at a wavelength of 320 nm.

Description

  The present invention relates to a cellulose ester film, a method for producing the same, and a polarizing plate. More specifically, in adhesion to a polarizer, excellent adhesion with both polyvinyl alcohol (also referred to as PVA) -based water glue and ultraviolet curable adhesive. In addition, the present invention relates to a cellulose ester film that is a thin film and excellent in retardation development, a manufacturing method thereof, and a polarizing plate.

  In recent years, further enlargement, thinning, and high definition of liquid crystal display devices are required to further increase the width and thickness of polarizing plates and improve display quality.

  Conventionally, a cellulose ester film has been used as a protective film for a polarizing plate, but cellulose triacetate that has been used in the past has been used to achieve further widening, thinning, and display quality such as contrast due to retardation. There was a problem in using a film (also referred to as a TAC film) as a retardation film as it was.

  Originally, a TAC film has a property that a retardation (also referred to as retardation) is difficult to occur. Therefore, a VA mode type liquid crystal is formed by performing a stretching treatment or the like by containing a retardation adjusting agent such as a retardation increasing agent. The production of an optical compensation film having a phase difference suitable for a display device has been studied. However, when the film is stretched at a high magnification for widening or thinning, additives such as the phase difference adjusting agent bleed out. As a result, haze increase was observed, and internal scattering increased due to whitening of the film itself due to stretching. As a result, the contrast decreased and the display quality was not excellent.

  On the other hand, a cellulose ester film using a cellulose ester having a low acyl group substitution degree, such as diacetyl cellulose (also referred to as DAC) having a low degree of acetyl group substitution, has a high retardation effect due to stretching treatment, but is further thinned. And the phase difference is insufficient. Therefore, even when the above-described DAC or the like is used, in the case of further thinning, it has been studied to add a retardation increasing agent to achieve both thinning and retardation development.

  In addition, a cellulose ester film can be saponified and bonded to a PVA film-based polarizer to produce a polarizing plate. However, a conventional ken as an adhesive when the cellulose ester film is bonded to a polarizer. In addition to the method using a chemical treatment and a PVA-based water paste, a method using an ultraviolet curable adhesive has begun to be adopted, and recently, it has been demanded that it can be bonded with both adhesives.

  However, the thinned cellulose ester film containing the DAC and the retardation increasing agent has a decrease in yield due to adhesion failure, film peeling, etc. when water glue or an ultraviolet curable adhesive is used as an adhesive. It has been found that there is a problem in providing satisfactory adhesion with both adhesives.

  According to the study by the present inventor, the film thickness tends to be non-uniform when the film is thinned by a stretching process at a high magnification or the like, and the standard deviation of the contact angle with pure water on the film surface (also referred to as deviation in the present application). It became clear that the spreadability of the adhesive was lowered, resulting in poor adhesion due to it. In addition, when an ultraviolet curable adhesive is used as an adhesive, it is usually irradiated with ultraviolet rays from the side of the retardation film that does not contain an ultraviolet absorber, but due to the structure of the retardation increasing agent, a compound that absorbs light particularly near 320 nm. In the case of using UV, it was found that ultraviolet rays were absorbed by the compound during the curing reaction by UV irradiation and did not reach the adhesive layer sufficiently, resulting in poor adhesion due to uncured.

  Furthermore, during the production of the DAC film, the retardation increasing agent is liable to generate minute foreign matters and precipitates due to compatibility with the DAC, and they move to the film surface by the stretching treatment, and the contact angle of the film surface. It has been found that the deviation of is increased to inhibit adhesion.

  A method for improving the deviation of the contact angle of the film surface is disclosed in Patent Document 1, but the disclosed technique is a method of melt-flowing a composition containing cellulose acetate propionate and no retardation increasing agent. The film is formed by the rolling method, and does not suggest the configuration of the present invention and the solution of the problem.

JP 2010-058410 A

  The present invention has been made in view of the above-mentioned problems and situations, and the solution is to have excellent adhesion with both PVA-based water glue and UV-curable adhesive in bonding with a polarizer, And it is providing the cellulose-ester film excellent in retardation development with the thin film, its manufacturing method, and a polarizing plate.

  In order to solve the above-mentioned problems, the present inventor contains diacetyl cellulose having a low degree of acetyl group substitution and a retardation increasing agent in the process of examining the cause of the above-mentioned problems, and has a contact angle with respect to a specific range of pure water. The present inventors have found that the problem can be solved by a cellulose ester film having a deviation range of the contact angle and having a light transmittance with respect to light of a specific wavelength.

  That is, the said subject which concerns on this invention is solved by the following means.

  1. A cellulose ester film containing at least a cellulose acetate (resin A) having a substitution degree of acetyl group in the range of 2.1 to 2.6 and a retardation increasing agent, the pure water on the surface of the cellulose ester film The contact angle is in the range of 30 to 75 °, and the standard deviation when the contact angle is measured at 20 points at regular intervals in the film width direction is in the range of 0.05 to 3.0 °. A cellulose ester film having a light transmittance of 80% or more at a wavelength of 320 nm.

  2. The cellulose ester according to item 1, wherein a standard deviation when the contact angle is measured at 20 points at equal intervals in the width direction of the film is in a range of 0.05 to 1.5 °. the film.

  3. The resin A and cellulose acetate propionate (resin B) having a substitution degree of acetyl group of 1.4 to 2.0 and a substitution degree of propionyl group of 0.5 to 1.5, The cellulose ester film described in the first or second item, wherein the mixing ratio of the resin B represented by the following formula 1 is contained in a range of 10 to 90%.

Formula 1 Mixing ratio of resin B = (mass of resin B) / (mass of resin A + mass of resin B) × 100 (%)
4). The cellulose ester film described in item 3, wherein the mixing ratio of the resin B is in the range of 20 to 70%.

  5. The absolute value of the difference of the total acyl group substitution degree of the resin A and the resin B satisfies the following formula 2, wherein the cellulose ester film is described in the third or fourth item.

Formula 2 | Total acyl group substitution degree of Resin B-Total acyl group substitution degree of Resin A | ≦ 0.3
6). The film thickness of the said cellulose-ester film exists in the range of 20-38 micrometers, The cellulose-ester film described in any one of Claim 1-5 characterized by the above-mentioned.

  7). The retardation value Re in the in-plane direction of the cellulose ester film represented by the following formula (i) is in the range of 45 to 60 nm, and the retardation value Rth in the film thickness direction represented by the following formula (ii) is The cellulose ester film according to any one of Items 1 to 6, which is in a range of 110 to 140 nm.

Formula _{(i): Re = (n} x -n y) × d (nm)
Formula (ii): Rth = {(n _x + n _y ) / 2−n _z } × d (nm)
In (formula (i) and Formula (ii), n _x is .n _y representing the refractive index in the direction x in which the refractive index is maximized in the plane direction of the film in-plane direction of the film, the direction x Represents the refractive index in the direction y orthogonal to _nz , _nz represents the refractive index in the thickness direction z of the film, and d represents the thickness (nm) of the film.)
8). The cellulose ester according to any one of items 1 to 7, wherein the retardation increasing agent is a nitrogen-containing heterocyclic compound having a structure represented by the following general formula (1): the film.

（式中Ａはピラゾール環又はイミダゾール環を表す。Ａｒ_１及びＡｒ_２はそれぞれ芳香族炭化水素環又は芳香族複素環を表し、置換基を有してもよい。Ｒ_１は水素原子、アルキル基、アシル基、スルホニル基、アルキルオキシカルボニル基、又はアリールオキシカルボニル基を表す。ｑは１〜２の整数を表す。ｎ及びｍはそれぞれ１〜３の整数を表す。）
９．前記リターデーション上昇剤が、セルロースエステルに対し、０．１〜５質量％の割合で含まれることを特徴とする第１項から第８項までのいずれか一項に記載したセルロースエステルフィルム。

(In the formula, A represents a pyrazole ring or an imidazole ring. Ar ₁ and Ar ₂ each represent an aromatic hydrocarbon ring or an aromatic heterocyclic ring and may have a substituent. R ₁ represents a hydrogen atom or an alkyl group. An acyl group, a sulfonyl group, an alkyloxycarbonyl group, or an aryloxycarbonyl group, q represents an integer of 1 to 2, and n and m each represents an integer of 1 to 3.
9. The cellulose ester film according to any one of items 1 to 8, wherein the retardation increasing agent is contained in a proportion of 0.1 to 5% by mass with respect to the cellulose ester.

10. A method for producing a cellulose ester film for producing a cellulose ester film according to any one of items 1 to 9,
Preparing a dope by dissolving cellulose ester in a solvent and filtering,
Casting a dope from a casting die onto a support that is a rotationally driven metal endless belt or a rotating drum to form a web;
Peeling the web from the support to form a film,
Stretching and drying the film after peeling,
A step of winding the dried film into a roll,
The dope is filtered using a leaf disc filter at a temperature within the range of (boiling point + 5 ° C.) to (boiling point + 20 ° C.) at 1 atm of the main solvent, and the residual solvent amount is in the range of 2 to 10% by mass. The stretching method defined by the following formula 3 in the width direction of the film is stretched within a range of 250 to 500% / min.

Formula 3 Stretching speed (% / min) = [(d1 / d2) -1] × 100 (%) / t
(In Formula 3, d1 is the width dimension in the stretching direction of the cellulose ester film after stretching, d2 is the width dimension in the stretching direction of the cellulose ester film before stretching, and t is the time required for stretching (min) .)
11. A polarizing plate, wherein the cellulose ester film described in any one of items 1 to 9 is bonded to a polarizer with water paste.

  12 A polarizing plate, wherein the cellulose ester film described in any one of items 1 to 9 is bonded to a polarizer with an ultraviolet curable adhesive.

  By the above means of the present invention, a cellulose ester film having excellent adhesion with both a PVA-based water paste and an ultraviolet curable adhesive in adhesion to a polarizer, and having a thin film and excellent retardation development, A manufacturing method and a polarizing plate can be provided.

  The expression mechanism or action mechanism of the effect of the present invention is not clear, but is presumed as follows.

  Cellulose ester film containing DAC and retardation increasing agent that can easily achieve thinning and high retardation by stretching treatment, the film thickness tends to be non-uniform when thinning by stretching treatment by high magnification, etc. The standard deviation (hereinafter also referred to as deviation) of the contact angle with respect to pure water on the film surface is increased, and the spreadability of PVA water paste or UV curable adhesive is likely to deteriorate, resulting in poor adhesion. It was. This is because the fine foreign matters and precipitates generated due to the poor compatibility with the DAC of the retardation increasing agent move to the film surface during the stretching treatment to form minute irregularities on the film surface. It is assumed that the deviation is increased.

  In addition, when using an ultraviolet curable adhesive, it has been found that unless the light transmittance of the cellulose ester film at a wavelength of 320 nm is set to a specific value or more, the adhesive is not sufficiently cured by ultraviolet rays, resulting in poor adhesion. . This factor is presumed to occur when a retardation increasing agent having ultraviolet absorbing ability, that is, having a low light transmittance at a wavelength of 320 nm, is used as a result of examining the components contained in the cellulose ester film in detail.

  As a result of examining the problem in detail, the present inventor contains a retardation increasing agent such that the deviation of the contact angle on the film surface is within a specific value range and the light transmittance at a wavelength of 320 nm is a specific value or more. It has been found that the cellulose ester film can improve the adhesion failure of the PVA-based water paste and the UV curable adhesive, and can produce a polarizing plate using both adhesives. In the process, selecting a specific retardation increasing agent having light transmittance according to the present invention, and adjusting filtration conditions and stretching conditions (residual solvent amount, stretching speed) in producing a cellulose ester film Is effective in controlling the deviation of the contact angle. This is achieved by adopting filtration conditions that are effective in removing fine foreign substances and precipitates caused by the retardation increasing agent, and by adopting stretching conditions at a relatively high speed, to the film surface of the fine foreign substances and precipitates. It is presumed that the movement of can be suppressed and the deviation of the contact angle can be reduced.

  Furthermore, in order to improve the deviation of the contact angle, a new finding that the deviation of the contact angle can be reduced by mixing and using cellulose acetate propionate (also referred to as CAP) as a resin to be used. Got.

  Although it is not clear regarding this mechanism of action, by mixing different kinds of cellulose esters, the acetyl group, the remaining unsubstituted group (OH group), and the propionyl group coexist in a specific ratio, thereby making hydrophilic The presence of OH groups, which are hydrophobic, and propionyl groups, which are slightly hydrophobic, balance the hydrophilicity and hydrophobicity of the film surface, affecting the affinity with organic solvents and plasticizers used in the production process. It is assumed that the deviation of the contact angle can be made smaller by smoothing.

  The coexistence of the acetyl group, the remaining unsubstituted group (OH group) and the propionyl group also improves the affinity with PVA water paste and UV curable adhesive, and improves the adhesive strength. It is assumed that

The figure which showed typically an example of the dope preparation process, casting process, and drying process of the solution casting film forming method preferable for this invention

  The cellulose ester film of the present invention is a cellulose ester film containing at least a cellulose acetate (resin A) having a degree of acetyl group substitution in the range of 2.1 to 2.6 and a retardation increasing agent, The contact angle of pure water on the surface of the cellulose ester film is in the range of 30 to 75 °, and the standard deviation when the contact angle is measured at 20 points at equal intervals in the width direction of the film is 0.05 to 3. It is characterized by being within a range of 0 ° and having a light transmittance of 80% or more at a wavelength of 320 nm. This feature is a technical feature common to the inventions according to claims 1 to 12. According to the above-mentioned constitutional requirements specified by the present invention, a cellulose ester having excellent adhesion with both PVA-based water glue and UV curable adhesive in adhesion to a polarizer, and having excellent retardation with a thin film A film is provided.

  The standard deviation of the contact angle is such that the standard deviation when measured at 20 points at regular intervals in the width direction of the film is within a range of 0.05 to 1.5 °, so that the spreadability of the adhesive is uniform. Thus, the adhesiveness with water glue or UV curable adhesive can be improved, which is more preferable.

  Further, the resin A and cellulose acetate propionate (resin B) having a substitution degree of acetyl group of 1.4 to 2.0 and a substitution degree of propionyl group of 0.5 to 1.5. And the mixing ratio of the resin B represented by the formula 1 is within the range of 10 to 90%, the hydrophilic and hydrophobic properties of the film surface are controlled, and the water on the film surface is controlled. From the viewpoint of providing uniform adhesiveness with water glue and an ultraviolet curable adhesive, it is preferable to adjust the balance between the hydrophilicity and hydrophobicity of the portion touched by. The mixing ratio of the resin B is more preferably in the range of 20 to 70%.

  Moreover, the absolute value of the difference in the total acyl group substitution degree of the resin A and the resin B satisfies the above-mentioned formula 2, so that the compatibility between the cellulose esters and the compatibility between the cellulose ester and the retardation increasing agent are improved. In addition, the generation of fine foreign matters and precipitates can be reduced, and the standard deviation of the contact angle on the film surface can be reduced, which is preferable.

  The film thickness of the cellulose ester film is in the range of 20 to 38 μm, which contributes to the production of a thin polarizing plate and the thinning of a liquid crystal display device using the film, and therefore is a preferable film thickness range. .

  In the VA mode liquid crystal display device, the retardation value Re in the in-plane direction of the cellulose ester film is in the range of 45 to 60 nm, and the retardation value Rth in the film thickness direction is in the range of 110 to 140 nm. From the viewpoint of optimizing visibility, this is a preferable range.

  Further, the retardation increasing agent is a nitrogen-containing heterocyclic compound containing a pyrazole ring or an imidazole ring having a structure represented by the general formula (A), in an addition amount that imparts a desired retardation value. Is a preferable compound because the light transmittance in the wavelength 380 nm measurement is 80% or more. Further, the nitrogen-containing heterocyclic compound is also a particularly preferable compound from the viewpoint of excellent compatibility with the cellulose ester and reducing the generation of fine foreign matters and precipitates and reducing the standard deviation of the contact angle on the film surface. . It is preferable that the retardation increasing agent is contained at a ratio of 0.1 to 5% by mass with respect to the cellulose ester in order to express the effect of the present invention.

The method for producing the cellulose ester film of the present invention comprises:
Preparing a dope by dissolving cellulose ester in a solvent and filtering,
Casting a dope from a casting die onto a support that is a rotationally driven metal endless belt or a rotating drum to form a web;
Peeling the web from the support to form a film,
Stretching and drying the film after peeling,
A step of winding the dried film into a roll,
The dope is filtered using a leaf disk filter at a temperature within the range of (boiling point + 5 ° C.) to (boiling point + 20 ° C.) at 1 atm of the main solvent, and the residual solvent amount is in the range of 2 to 10% by mass. In the above, stretching within the range of 250 to 500% / min of the stretching speed defined by the above-mentioned formula 3 effectively removes fine foreign matters and precipitates from the dope, and onto the surface of the foreign matter during stretching. From the viewpoint of reducing the standard deviation of the contact angle on the film surface by controlling the movement of the film, this is a preferable production method.

  The cellulose ester film of the present invention is preferably bonded to a polarizing plate using water paste to form a polarizing plate, and is bonded to the polarizing plate using an ultraviolet curable adhesive to form a polarizing plate. It is preferable.

  Hereinafter, the present invention, its components, and modes and modes for carrying out the present invention will be described in detail. In addition, in this application, "-" is used in the meaning which includes the numerical value described before and behind that as a lower limit and an upper limit.

<< Outline of Cellulose Ester Film of the Present Invention >>
The cellulose ester film of the present invention is a cellulose ester film containing at least a cellulose acetate (resin A) having a degree of acetyl group substitution in the range of 2.1 to 2.6 and a retardation increasing agent, The contact angle of pure water on the surface of the cellulose ester film is in the range of 30 to 75 °, and the standard deviation when the contact angle is measured at 20 points at equal intervals in the width direction of the film is 0.05 to 3. The light transmittance at a wavelength of 320 nm is 80% or more within a range of 0 °. With such a configuration, the PVA water glue and the UV curable adhesive are used for bonding with a polarizer. The present invention provides a cellulose ester film that has excellent adhesiveness in both and is a thin film and excellent in retardation.

  When the contact angle of pure water on the surface of the cellulose ester film is within a range of 30 to 75 °, it is possible to bond to the polarizer with both water glue and ultraviolet curable adhesive.

  If it is less than 30 °, it is too hydrophilic, and when it is made into a roll film, the films tend to stick together, and the flatness of the film deteriorates. If it exceeds 75 °, the contact angle is not sufficiently lowered even when saponified, and the adhesiveness with water paste is poor.

  Examples of the means for controlling the cellulose ester film of the present invention within the range of the contact angle include adjustment of the degree of substitution of the cellulose ester and the amount of additive typified by a plasticizer.

  In addition, the standard deviation is within a range of 0.05 to 3.0 °, so that both the water paste and the ultraviolet curable adhesive can easily spread uniformly, and the viewpoint of bonding to the polarizer This is a preferable deviation.

  If it exceeds 3.0 °, the flatness and adhesiveness at the time of adhesion of both water paste and ultraviolet curable adhesive deteriorate. Although the lower limit of the deviation is 0.05 °, this is a lower limit value of the deviation that can be practically adjusted, and there is no merit of further reducing the deviation.

  Means for controlling the cellulose ester film of the present invention within the range of deviation of the above contact angle is to adjust the filtration conditions and stretching conditions (residual solvent amount, stretching speed) described later, to mix CAP into the DAC as a resin, Use of a specific compound as a retardation adjusting agent can be mentioned.

  In the present invention, the contact angle defines a value before the saponification treatment is performed, but the contact angle tends to be lowered by the normal saponification treatment. Actually, when the contact angle of pure water on the surface of the cellulose ester film is in the range of 30 to 75 °, the contact angle after the saponification treatment is reduced to about 15 to 45 °, but the effect of the present invention is obtained. From the viewpoint, it has been confirmed that adjusting the contact angle before the saponification treatment to the above range is effective from many experimental results.

  Similarly, the saponification treatment may affect the standard deviation of the contact angle. However, the standard deviation after the saponification treatment does not actually fluctuate. From the viewpoint of obtaining the effects of the present invention, It is effective to adjust the standard deviation of the contact angle before the conversion to the above range.

  In the case of an ultraviolet curable adhesive, instead of not performing the saponification treatment, a hydrophilic treatment such as a corona discharge treatment or a plasma discharge treatment may be performed. Since the behavior is the same as the behavior of the standard deviation, the effect of the present invention can be obtained by adjusting the contact angle and the standard deviation of the cellulose ester film surface defined in the present invention.

  The contact angle of pure water on the film surface was measured by leaving the cellulose ester film sample for 24 hours in an atmosphere at a temperature of 23 ° C. and a relative humidity of 55%, and then in an atmosphere at a temperature of 23 ° C. and a relative humidity of 55%. Using a meter (trade name DropMaster DM100, manufactured by Kyowa Interface Science Co., Ltd.), 1 μl of pure water is dropped, and the contact angle of pure water after 1 minute is measured. The measurement is performed at 20 points at regular intervals in the width direction of the film, and the average value excluding the maximum value and the minimum value is used as the contact angle, and the standard deviation of the 20 points is obtained at the same time.

  Further, the light transmittance at a wavelength of 320 nm is obtained by using a spectrophotometer (U-3300 manufactured by Hitachi, Ltd.) for any 10 points of a cellulose ester film sample in an atmosphere of a temperature of 23 ° C. and a relative humidity of 55%. The light transmittance (%) at a measurement wavelength of 320 nm is measured and averaged.

≪Cellulose ester≫
The cellulose ester film of the present invention is characterized by containing cellulose acetate (resin A) having an acetyl group substitution degree in the range of 2.1 to 2.6. When the degree of acetyl group substitution of cellulose acetate is less than 2.1, film surface quality may deteriorate due to an increase in dope viscosity. On the other hand, when the degree of acetyl group substitution is larger than 2.6, it is difficult to obtain a necessary retardation value, and haze-up due to an increase in stretching tension occurs.

  Here, “acetyl group substitution degree” represents the total of the ratios of esterification of hydroxy groups by acetyl groups at the 2-position, 3-position and 6-position of glucose of the repeating unit in the cellulose ester. Specifically, when the hydroxy groups at the 2nd, 3rd and 6th positions of cellulose are all 100% esterified, the degree of substitution is 3 at the maximum.

  Therefore, in this application, "acetyl group substitution degree" means the substitution degree which expressed the total of the acetyl group substitution degree of the some glucose unit which comprises a cellulose ester as an average value per unit. The same applies to the degree of substitution of the propionyl group described later.

[Cellulose acetate (resin A)]
The cellulose ester film of the present invention is characterized by being composed mainly of cellulose acetate (resin A) having an acetyl group substitution degree in the range of 2.1 to 2.6. The main component as used in the present invention means that when cellulose acetate having a degree of acetyl group substitution within the range of 2.1 to 2.6 is used alone among cellulose acetates constituting the cellulose ester film, It means 60% by mass or more, preferably 80% by mass or more, and more preferably 95% by mass or more. The average degree of substitution of the acetyl group is preferably in the range of 2.15 to 2.58, and the retardation development property is also high, which is preferable for use as a retardation film.

  The average degree of substitution of acetyl groups in cellulose acetate can be determined by measurement according to ASTM-D817-96.

  In the present invention, if the degree of acetyl group substitution of the cellulose acetate to be applied is within the above range, the effects of the present invention are exhibited, the casting suitability at the time of film formation is high, and the handleability is excellent as a film. The characteristics can be realized.

  The number average molecular weight (Mn) of the cellulose acetate is preferably in the range of 125,000 to 155000, and more preferably in the range of 129000 to 152000. Moreover, it is preferable that a weight average molecular weight (Mw) exists in the range of 265000-310000. The ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is preferably in the range of 1.4 to 2.5, more preferably in the range of 1.5 to 2.0. .

  In the present invention, two or more cellulose acetates can be mixed and used.

  The weight average molecular weight Mw and the number average molecular weight Mn of cellulose acetate can be measured using gel permeation chromatography (GPC).

  The measurement conditions are as follows.

Solvent: Methylene chloride Column: Shodex K806, K805, K803G (Used by connecting three Showa Denko Co., Ltd.)
Column temperature: 25 ° C
Sample concentration: 0.1% by mass
Detector: RI Model 504 (manufactured by GL Sciences)
Pump: L6000 (manufactured by Hitachi, Ltd.)
Flow rate: 1.0ml / min
Calibration curve: Standard polystyrene STK standard polystyrene (manufactured by Tosoh Corp.) Mw = 500 to 1,000,000 calibration curves with 13 samples were used. Thirteen samples are used at approximately equal intervals.

  The cellulose acetate according to the present invention can be produced by a conventional method such as a sulfuric acid catalyst method, an acetic acid method, a methylene chloride method, and the raw materials are not particularly limited, but cotton linter, wood pulp (derived from coniferous trees, derived from broadleaf trees) ), Kenaf and the like. Moreover, the cellulose acetate obtained from them can be mixed and used in arbitrary ratios, respectively. Moreover, the cellulose acetate which concerns on this invention is compoundable with reference to the method of Unexamined-Japanese-Patent No. 10-45804 and Unexamined-Japanese-Patent No. 2005-281645, for example.

  As a commercial item of cellulose acetate (cellulose diacetate) according to the present invention, L20, L30, L40, L50 manufactured by Daicel Corporation, Ca398-3, Ca398-6, Ca398- manufactured by Eastman Chemical Japan Co., Ltd. 10, Ca398-30, and Ca394-60S.

[Cellulose acetate propionate (resin B)]
The cellulose ester film of the present invention is a cellulose having the cellulose acetate resin and the acetyl group substitution degree in the range of 1.4 to 2.0 and the propionyl group substitution degree in the range of 0.5 to 1.5. It is preferable to contain acetate propionate (resin B) so that the mixing ratio of the resin B represented by the following formula 1 is in the range of 10 to 90%.

Formula 1 Mixing ratio of resin B = (mass of resin B) / (mass of resin A + mass of resin B) × 100 (%)
Cellulose acetate propionate (resin B) reduces the contact angle deviation by mixing 10% or more, and exhibits the effect of improving adhesiveness with water glue or UV curable adhesive. By mixing, the adhesiveness and the retardation development can be made compatible. From the viewpoint of increasing the retardation development property, the mixing ratio of the resin B is more preferably in the range of 20 to 70%, and particularly preferably in the range of 30 to 60%. As described above, this is because the acetyl group, the remaining unsubstituted group (OH group), and the propionyl group coexist in a specific ratio, so that the hydrophilic OH group is slightly hydrophobic. The presence of the propionyl group balances the hydrophilicity and hydrophobicity of the film surface. Therefore, it is presumed that it affects the affinity with the organic solvent and plasticizer used in the production process and smoothes the film surface.

  In addition, since cellulose acetate propionate (resin B) is a resin excellent in adhesiveness with an adhesive, the resin B is mixed with the resin A, so that the fineness caused by the retardation increasing agent present on the film surface can be obtained. It is possible to improve the adhesiveness of the surface by wrapping around the foreign matter or precipitate with the resin B, and to further improve the adhesive effect by the water glue or the ultraviolet curable adhesive according to the present invention.

  The resin B may be mixed during the dope preparation process of the cellulose ester film, or may be mixed in advance to produce pellets.

  The cellulose acetate propionate (resin B) according to the present invention has an acyl group having 2 to 4 carbon atoms as a substituent, the substitution degree of the acetyl group is X, and the substitution degree of the propionyl group is Y It is preferable that the following formulas (I) to (III) are simultaneously satisfied.

Formula (I) 2.0 ≦ X + Y ≦ 2.95
Formula (II) 1.4 ≦ X ≦ 2.0
Formula (III) 0.5 ≦ Y ≦ 1.5
Among them, 0.8 ≦ Y ≦ 1.0 is preferable, and 2.2 ≦ X + Y ≦ 2.7 is preferable from the viewpoint of phase difference development.

  Furthermore, it is preferable that the absolute value of the difference between the total acyl group substitution degrees of the resin A and the resin B satisfies the following formula 2.

Formula 2 | Total acyl group substitution degree of Resin B-Total acyl group substitution degree of Resin A | ≦ 0.3
By mixing cellulose acetate propionate having a total acyl group substitution degree close to the total acyl group substitution degree of cellulose acetate of resin A, the compatibility between the resin and the retardation raising agent is improved. Precipitation resistance improves and generation | occurrence | production of a fine foreign material and a precipitate can be suppressed.

  The number average molecular weight Mn of the cellulose acetate propionate is preferably in the range of 60,000 to 300,000 because the mechanical strength of the resulting film becomes strong. More preferably, the number average molecular weight is in the range of 70,000 to 200,000, and the precipitation resistance of the additive is improved in the above range.

  The cellulose ester film of the present invention may be used in combination with other resins as long as the effects of the present invention are not impaired.

  As other resins, cellulose derivatives other than the above-described cellulose esters (for example, cellulose ester resins, cellulose ether resins, etc.), polycarbonate resins, polystyrene resins, polysulfone resins, polyester resins, polyarylate resins, (Meth) acrylic resins, olefin resins (for example, norbornene resins, cyclic olefin resins, cyclic conjugated diene resins, vinyl alicyclic hydrocarbon resins) and the like.

≪Retardation raising agent≫
The retardation increasing agent as used herein refers to a cellulose ester film in which the retardation value Rth (measured at a wavelength of 590 nm) in the thickness direction of a cellulose ester film containing 3 parts by mass of the compound with respect to 100 parts by mass of the cellulose ester is not added. The compound which has a function which shows a value 1.1 times or more compared with a film.

  The retardation increasing agent according to the present invention is not particularly limited, and for example, a well-known disk having an aromatic ring described in paragraphs [0143] to [0179] of JP-A-2006-113239. -Like compounds (1,3,5-triazine compounds), rod-like compounds described in paragraphs [0106] to [0112] of JP-A-2006-113239, paragraphs [0118] to [0133] of JP-A-2012-214682 Although the pyrimidine-type compound of this invention etc. can be used, when bonding the cellulose-ester film of this invention using an ultraviolet curable adhesive, the compound which absorbs the ultraviolet rays irradiated in order to harden | cure and inhibits hardening reaction is used. The use is not preferable for achieving the object of the present invention. Therefore, the cellulose ester film containing the retardation increasing agent in an addition amount that expresses a desired retardation value has a light transmittance of at least 80% at a wavelength of 320 nm. It becomes a necessary characteristic when pasting. The light transmittance is preferably 90% or more.

  As a result of detailed studies on the retardation increasing agent, the present inventor has found that the following nitrogen-containing heterocyclic compound has a phase difference, a light transmittance of a cellulose ester film at a wavelength of 320 nm, and a minute foreign matter due to an improvement in compatibility with the cellulose ester. It was found that it is a retardation increasing agent preferable for the present invention.

[Nitrogen-containing heterocyclic compounds]
The retardation increasing agent according to the present invention is preferably a nitrogen-containing heterocyclic compound having a structure represented by the following general formula (1).

  A preferable addition amount is in the range of 0.1 to 5% by mass with respect to the cellulose ester. In this range, the retardation is exhibited, the light transmittance at a wavelength of 320 nm, and the slight increase due to the improvement in compatibility with the cellulose ester. Both suppression of the generation of foreign matter and precipitates can be satisfied. The addition amount is more preferably 1 to 5% by mass, and particularly preferably 2 to 5% by mass. The addition amount varies depending on the type of cellulose ester and the type of the compound, but the optimum value of the addition amount can be determined by the desired retardation value of the cellulose ester film of the present invention.

  The nitrogen-containing heterocyclic compound is characterized by controlling the hydrogen bonding property of cellulose ester by CH / π interaction with cellulose ester and having both functions of a retardation increasing agent and a wavelength dispersion adjusting agent with one compound. It has excellent compatibility when combined with a cellulose ester, and there is little generation of fine foreign matters and precipitates during the production process. For example, 1,3,5-triazine-based retardation increasing agents and the like have a weak CH / π interaction, so that they are slightly inferior in compatibility and easily generate foreign substances. There is a tendency to increase the deviation of the contact angle according to the invention.

  CH / π interaction refers to the compatibility of hydrogen bond donating sites such as cellulose esters (for example, hydrogen atoms of hydroxy groups) and hydrogen bond accepting sites (for example, carbonyl oxygen atoms of ester groups) with additives. It is a bond interaction between the hydrogen bonding site present in the main chain or side chain of the resin and the π electrons of the additive aromatic compound. Due to this CH / π interaction, the compatibility is excellent.

  When the CH / π interaction is formed using the hydrogen bonding site of the resin (CH of the cellulose ester) and π of the additive, it is naturally better that the π property of the additive is stronger. There is an index called a NICS (nucleus-independent chemical shift) value as an example that directly represents the strength of the π property.

  This NICS value is an index used for quantification of aromaticity by magnetic properties. If the ring is aromatic, the ring current effect strongly shields the center of the ring, and conversely if it is antiaromatic. Anti-shielding (J. Am. Chem. Soc. 1996, 118, 6317). Depending on the magnitude of the NICS value, it is possible to determine the strength of the ring current, that is, the degree of contribution of π electrons to the aromaticity of the ring. Specifically, it represents the chemical shift (calculated value) of a virtual lithium ion arranged directly in the center of the ring, and the larger the value, the stronger the π property.

  Several reports have been made regarding the measured NICS values. For example, Canadian Journal of Chemistry. , 2004, 82, 50-69 (Document A) and The Journal of Organic Chemistry. , 2000, 67, 1333-1338 (Document B).

  Specifically, a pyrrole ring (-14.87), a thiophene ring (-14.09) furan rather than an aromatic hydrocarbon such as a benzene ring (-7.98) or a naphthalene ring (-8.11). 5-membered aromatic heterocycles such as ring (-12.42), pyrazole ring (-13.82), or imidazole ring (-13.28), triazole ring (-13.18), oxadiazole ring ( -12.44) or 6-membered aromatic hydrocarbon rings such as thiazole ring (-12.82) have a larger NICS value, and such aromatic 5-membered rings or aromatic 6-membered rings It is predicted that the CH / π interaction can be strengthened by using the compound having the above (the NICS value is shown in parentheses). Among these, a pyrazole ring or an imidazole ring is preferable because of excellent compatibility with the cellulose ester.

（式中Ａはピラゾール環又はイミダゾール環を表す。Ａｒ_１及びＡｒ_２はそれぞれ芳香族炭化水素環又は芳香族複素環を表し、置換基を有してもよい。Ｒ_１は水素原子、アルキル基、アシル基、スルホニル基、アルキルオキシカルボニル基、又はアリールオキシカルボニル基を表す。ｑは１〜２の整数を表す。ｎ及びｍはそれぞれ１〜３の整数を表す。）
Ａｒ_１及びＡｒ_２で表される芳香族炭化水素環又は芳香族複素環は、５員若しくは６員の芳香族炭化水素環又は芳香族複素環であることが好ましく、例えば、ベンゼン環、ピロール環、ピラゾール環、イミダゾール環、１，２，３−トリアゾール環、１，２，４−トリアゾール環、テトラゾール環、フラン環、オキサゾール環、イソオキサゾール環、オキサジアゾール環、イソオキサジアゾール環、チオフェン環、チアゾール環、イソチアゾール環、チアジアゾール環、イソチアジアゾール環等が挙げられる。

(In the formula, A represents a pyrazole ring or an imidazole ring. Ar ₁ and Ar ₂ each represent an aromatic hydrocarbon ring or an aromatic heterocyclic ring and may have a substituent. R ₁ represents a hydrogen atom or an alkyl group. An acyl group, a sulfonyl group, an alkyloxycarbonyl group, or an aryloxycarbonyl group, q represents an integer of 1 to 2, and n and m each represents an integer of 1 to 3.
The aromatic hydrocarbon ring or aromatic heterocyclic ring represented by Ar ₁ and Ar ₂ is preferably a 5-membered or 6-membered aromatic hydrocarbon ring or aromatic heterocyclic ring, such as a benzene ring or a pyrrole ring. , Pyrazole ring, imidazole ring, 1,2,3-triazole ring, 1,2,4-triazole ring, tetrazole ring, furan ring, oxazole ring, isoxazole ring, oxadiazole ring, isoxadiazole ring, thiophene Ring, thiazole ring, isothiazole ring, thiadiazole ring, isothiadiazole ring and the like.

  The 5-membered or 6-membered aromatic hydrocarbon ring or aromatic heterocycle may have a substituent. Examples of the substituent include a halogen atom (a fluorine atom, a chlorine atom, a bromine atom, an iodine atom). Etc.), alkyl group (methyl group, ethyl group, n-propyl group, isopropyl group, tert-butyl group, n-octyl group, 2-ethylhexyl group, etc.), cycloalkyl group (cyclohexyl group, cyclopentyl group, 4-n) -Dodecylcyclohexyl group etc.), alkenyl group (vinyl group, allyl group etc.), cycloalkenyl group (2-cyclopenten-1-yl, 2-cyclohexen-1-yl group etc.), alkynyl group (ethynyl group, propargyl group etc.) ), Aromatic hydrocarbon ring groups (phenyl group, p-tolyl group, naphthyl group, etc.), aromatic heterocyclic groups (2-pyrrole group, 2-furyl group, -Thienyl group, pyrrole group, imidazolyl group, oxazolyl group, thiazolyl group, benzoimidazolyl group, benzoxazolyl group, 2-benzothiazolyl group, pyrazolinone group, pyridyl group, pyridinone group, 2-pyrimidinyl group, triazine group, pyrazole group, 1,2,3-triazole group, 1,2,4-triazole group, oxazole group, isoxazole group, 1,2,4-oxadiazole group, 1,3,4-oxadiazole group, thiazole group, Isothiazole group, 1,2,4-thiodiazole group, 1,3,4-thiadiazole group, etc.), cyano group, hydroxy group, nitro group, carboxy group, alkoxy group (methoxy group, ethoxy group, isopropoxy group, tert) -Butoxy group, n-octyloxy group, 2-methoxyethoxy group, etc.), aryl Oxy groups (phenoxy group, 2-methylphenoxy group, 4-tert-butylphenoxy group, 3-nitrophenoxy group, 2-tetradecanoylaminophenoxy group, etc.), acyloxy groups (formyloxy group, acetyloxy group, pivaloyloxy group) , Stearoyloxy group, benzoyloxy group, p-methoxyphenylcarbonyloxy group, etc.), amino group (amino group, methylamino group, dimethylamino group, anilino group, N-methyl-anilino group, diphenylamino group, etc.), acylamino Groups (formylamino group, acetylamino group, pivaloylamino group, lauroylamino group, benzoylamino group, etc.), alkyl and arylsulfonylamino groups (methylsulfonylamino group, butylsulfonylamino group, phenylsulfonylamino group, 2, 3, 5-trichlorophenylsulfonylamino group, p-methylphenylsulfonylamino group, etc.), mercapto group, alkylthio group (methylthio group, ethylthio group, n-hexadecylthio group, etc.), arylthio group (phenylthio group, p-chlorophenylthio group, m -Methoxyphenylthio group, etc.), sulfamoyl group (N-ethylsulfamoyl group, N- (3-dodecyloxypropyl) sulfamoyl group, N, N-dimethylsulfamoyl group, N-acetylsulfamoyl group, N -Benzoylsulfamoyl group, N- (N'-phenylcarbamoyl) sulfamoyl group, etc.), sulfo group, acyl group (acetyl group, pivaloylbenzoyl group, etc.), carbamoyl group (carbamoyl group, N-methylcarbamoyl group, N, N-dimethylcarbamoyl group, N, N Di -n- octylcarbamoyl group, and each group such as N- (methylsulfonyl) carbamoyl group).

Specific examples of R ₁ include halogen atoms (fluorine atom, chlorine atom, bromine atom, iodine atom, etc.), alkyl groups (methyl group, ethyl group, n-propyl group, isopropyl group, tert-butyl group, n-octyl group). Group, 2-ethylhexyl group, etc.), acyl group (acetyl group, pivaloylbenzoyl group, etc.), sulfonyl group (eg, methylsulfonyl group, ethylsulfonyl group, etc.), alkyloxycarbonyl group (eg, methoxycarbonyl group), An aryloxycarbonyl group (for example, phenoxycarbonyl group etc.) etc. are mentioned.

  q represents the integer of 1-2, n and m represent the integer of 1-3, respectively.

  The molecular weight of the compound having the structure represented by the general formula (1) is not particularly limited. However, the smaller the value, the better the compatibility with the resin, and the larger the value, the higher the retardation value fluctuation suppression effect with respect to environmental humidity changes. 150 to 2000 is preferable, 200 to 1500 is more preferable, and 300 to 1000 is more preferable.

  Although the specific example of the compound which has a structure represented by General formula (1) used for this invention below is shown, this invention is not limited at all by the following specific examples. In addition, the following specific examples may be a tautomer and may form a hydrate, a solvate or a salt.

(Synthesis of Exemplified Compound 1)
Exemplary compound 1 can be synthesized by the following scheme.

  To 520 ml of dehydrated tetrahydrofuran was added 80 g (0.67 mol) of acetophenone and 52 g (0.27 mol) of dimethyl isophthalate. . After stirring for 3 hours under ice-water cooling, the mixture was stirred for 12 hours under water-cooling. Concentrated sulfuric acid was added to the reaction solution for neutralization, and then pure water and ethyl acetate were added for liquid separation, and the organic layer was washed with pure water. The organic layer was dried over magnesium sulfate, and the solvent was distilled off under reduced pressure. 55.2 g of intermediate A was obtained by adding methanol to the obtained crude crystal and suspending and washing it.

  Intermediate A 55 g (0.15 mol) was added to tetrahydrofuran 300 ml and ethanol 200 ml, and 18.6 g (0.37 mol) of hydrazine monohydrate was added dropwise little by little while stirring at room temperature. After completion of dropping, the mixture was heated to reflux for 12 hours. Pure water and ethyl acetate were added to the reaction solution for liquid separation, and the organic layer was washed with pure water. The organic layer was dried over magnesium sulfate, and the solvent was distilled off under reduced pressure. The obtained crude crystals were purified by silica gel chromatography (ethyl acetate / heptane) to obtain 27 g of Exemplified Compound 1.

The ¹ H-NMR spectrum of the obtained exemplary compound 1 is as follows. In order to avoid complication of chemical shift due to the presence of tautomers, the measurement was performed by adding a few drops of trifluoroacetic acid to the measurement solvent.

¹ H-NMR (400 MHz, solvent: heavy DMSO ((D ₃ c) ₂ S═O), standard: tetramethylsilane) δ (ppm): 8.34 (1H, s), 7.87 to 7.81 (6H, m), 7.55 to 7.51 (1H, m), 7.48-7.44 (4H, m), 7.36-7.33 (2H, m), 7.29 (1H , S)
Other exemplary compounds can be synthesized by the same method.

≪Other additives≫
The cellulose ester film of the present invention preferably contains other additives in order to control the contact angle with respect to water on the film surface and the standard deviation of the contact angle. Examples thereof include a plasticizer, Examples thereof include an antioxidant, a light stabilizer, an antistatic agent, and a release agent. The compound used more effectively preferably contains a plasticizer, and among them, the use of a sugar ester and a polycondensed ester described below is preferable for controlling the deviation of the contact angle on the film surface.

[Plasticizer]
<Sugar ester>
The sugar ester used in the present invention is preferably a sugar ester in which at least one pyranose ring or furanose ring is 1 to 12 and all or part of the OH group of the structure is esterified. The sugar ester used in the present invention is preferably added for the purpose of preventing hydrolysis.

  The sugar ester used in the present invention is a compound containing at least one of a furanose ring and a pyranose ring, and may be a monosaccharide or a polysaccharide having 2 to 12 sugar structures linked together. The sugar ester is preferably a compound in which at least one OH group of the sugar structure is esterified. In the sugar ester used in the present invention, the average ester substitution degree is preferably within the range of 4.0 to 8.0, and more preferably within the range of 5.0 to 7.5.

  The sugar ester used in the present invention is not particularly limited, and examples thereof include sugar esters represented by the following general formula (A).

Formula (A)
_{(HO) m -G- (O-} C (= O) -R 2) n
In the general formula (A), G represents a monosaccharide or disaccharide residue, R ² represents an aliphatic group or an aromatic group, and m is directly bonded to the monosaccharide or disaccharide residue. N is the total number of — (O—C (═O) —R ² ) groups directly bonded to the monosaccharide or disaccharide residue, 3 ≦ m + n ≦ 8, and n ≠ 0.

The sugar ester having the structure represented by the general formula (A) is a single kind of hydroxy group (m) and-(O—C (═O) —R ² ) group in which the number (n) is fixed. It is difficult to isolate as a compound, and it is known that a compound in which several components different in m and n in the formula are mixed is obtained. Therefore, the performance as a mixture in which the number (m) of hydroxy groups and the number (n) of-(O—C (═O) —R ² ) groups are important is important. In the case of the cellulose ester film of the present invention, A sugar ester having an average ester substitution degree in the range of 5.0 to 7.5 is preferable.

  In the general formula (A), G represents a monosaccharide or disaccharide residue. Specific examples of monosaccharides include allose, altrose, glucose, mannose, gulose, idose, galactose, talose, ribose, arabinose, xylose, lyxose, and the like.

  Specific examples of the compound having a monosaccharide residue of the sugar ester represented by the general formula (A) are shown below, but the present invention is not limited to these exemplified compounds.

  Specific examples of the disaccharide residue include trehalose, sucrose, maltose, cellobiose, gentiobiose, lactose, and isotrehalose.

  Although the specific example of the compound which has the disaccharide residue of the sugar ester represented with general formula (A) below is shown, this invention is not limited to these illustrated compounds.

In the general formula (A), R ² represents an aliphatic group or an aromatic group. Here, the aliphatic group and the aromatic group may each independently have a substituent.

In general formula (A), m is the total number of hydroxy groups directly bonded to the monosaccharide or disaccharide residue, and n is directly bonded to the monosaccharide or disaccharide residue. The total number of — (O—C (═O) —R ² ) groups. Further, it is necessary that 3 ≦ m + n ≦ 8, and it is preferable that 4 ≦ m + n ≦ 8. Further, n ≠ 0. When n is 2 or more, the — (O—C (═O) —R ² ) groups may be the same as or different from each other.

The aliphatic group in the definition of R ² may be linear, branched or cyclic, and preferably has 1 to 25 carbon atoms, more preferably 1 to 20 carbon atoms. Those of ˜15 are particularly preferred. Specific examples of the aliphatic group include, for example, methyl, ethyl, n-propyl, iso-propyl, cyclopropyl, n-butyl, iso-butyl, tert-butyl, amyl, iso-amyl, tert-amyl, n- Examples include hexyl, cyclohexyl, n-heptyl, n-octyl, bicyclooctyl, adamantyl, n-decyl, tert-octyl, dodecyl, hexadecyl, octadecyl, didecyl and the like.

The aromatic group in the definition of R ² may be an aromatic hydrocarbon group or an aromatic heterocyclic group, and more preferably an aromatic hydrocarbon group. The aromatic hydrocarbon group preferably has 6 to 24 carbon atoms, and more preferably 6 to 12 carbon atoms. Specific examples of the aromatic hydrocarbon group include rings such as benzene, naphthalene, anthracene, biphenyl, and terphenyl. As the aromatic hydrocarbon group, a benzene ring, a naphthalene ring, and a biphenyl ring are particularly preferable. As the aromatic heterocyclic group, a ring containing at least one of an oxygen atom, a nitrogen atom or a sulfur atom is preferable. Specific examples of the heterocyclic ring include, for example, furan, pyrrole, thiophene, imidazole, pyrazole, pyridine, pyrazine, pyridazine, triazole, triazine, indole, indazole, purine, thiazoline, thiadiazole, oxazoline, oxazole, oxadiazole, quinoline, Examples of each ring include isoquinoline, phthalazine, naphthyridine, quinoxaline, quinazoline, cinnoline, pteridine, acridine, phenanthroline, phenazine, tetrazole, benzimidazole, benzoxazole, benzthiazole, benzotriazole, and tetrazaindene. As the aromatic heterocyclic group, a pyridine ring, a triazine ring, and a quinoline ring are particularly preferable.

  Next, although the preferable example of the sugar ester represented by general formula (A) is shown below, this invention is not limited to these illustrated compounds. The following exemplified compounds all have a melting point and 1% mass reduction temperature Td1 within the scope of the present invention.

  A sugar ester may contain two or more different substituents in one molecule, contains an aromatic substituent and an aliphatic substituent in one molecule, and contains two or more different aromatic substituents. Two or more different aliphatic substituents contained in one molecule can be contained in one molecule.

  It is also preferable to contain a mixture of two or more sugar esters. It is also preferable to simultaneously contain a sugar ester containing an aromatic substituent and a sugar ester containing an aliphatic substituent.

<Synthesis Example: Synthesis Example of Sugar Ester Represented by Formula (A)>
Below, an example of the synthesis | combination of the sugar ester which can be used suitably for this invention is shown.

Four-headed Kolben equipped with a stirrer, reflux condenser, thermometer and nitrogen gas inlet tube, 34.2 g (0.1 mol) of sucrose, 180.8 g (0.8 mol) of benzoic anhydride, pyridine 379.7 g (4.8 mol) of each were charged, and the temperature was raised while bubbling nitrogen gas from a nitrogen gas inlet tube under stirring, and esterification was carried out at 70 ° C. for 5 hours. Next, the inside of the Kolben was depressurized to 4 × 10 ² Pa or less, and after excess pyridine was distilled off at 60 ° C., the inside of the Kolben was depressurized to 1.3 × 10 Pa or less and the temperature was raised to 120 ° C. Most of the acid and benzoic acid formed were distilled off. Then, 1 L of toluene and 300 g of a 0.5% by mass sodium carbonate aqueous solution were added, and the mixture was stirred at 50 ° C. for 30 minutes, and then allowed to stand to separate a toluene layer. Finally, 100 g of water was added to the separated toluene layer, and after washing with water at room temperature for 30 minutes, the toluene layer was separated, and toluene was distilled off at 60 ° C. under reduced pressure (4 × 10 ² Pa or less). A mixture of compounds A-1, A-2, A-3, A-4 and A-5 was obtained. When the obtained mixture was analyzed by HPLC and LC-MASS, A-1 was 7% by mass, A-2 was 58% by mass, A-3 was 23% by mass, A-4 was 9% by mass, A-5. Was 3% by mass, and the average ester substitution degree of the sugar ester was 6.57. A part of the obtained mixture was purified by silica gel column chromatography to obtain A-1, A-2, A-3, A-4 and A-5 having a purity of 100%, respectively.

  The addition amount of the sugar ester is preferably in the range of 0.1 to 20% by mass with respect to the cellulose ester, and the addition in the range of 1 to 15% by mass improves the film hardness and the film tear strength. More preferable from the viewpoint.

<Polycondensed ester>
A preferable plasticizer for the cellulose ester film of the present invention includes a polycondensed ester containing a repeating unit obtained by reacting a dicarboxylic acid and a diol.

  The dicarboxylic acid constituting the polycondensed ester is an aromatic dicarboxylic acid, an aliphatic dicarboxylic acid or an alicyclic dicarboxylic acid, preferably an aromatic dicarboxylic acid. The dicarboxylic acid may be one kind or a mixture of two or more kinds.

  The diol constituting the polycondensed ester is an aromatic diol, an aliphatic diol or an alicyclic diol, preferably an aliphatic diol, and more preferably a diol having 1 to 4 carbon atoms. The diol may be one type or a mixture of two or more types.

  Among these, the polycondensed ester preferably contains a repeating unit obtained by reacting at least a dicarboxylic acid containing an aromatic dicarboxylic acid and a diol having 1 to 4 carbon atoms. The aromatic dicarboxylic acid and the aliphatic dicarboxylic acid are preferred. More preferably, it contains a repeating unit obtained by reacting a dicarboxylic acid containing an acid with a diol having 1 to 4 carbon atoms.

  Both ends of the molecule of the polycondensed ester may be sealed or unsealed, but are preferably sealed from the viewpoint of reducing the moisture permeability of the film.

  The polycondensed ester is preferably a compound having a structure represented by the following general formula (2) or (3). In the following formula, n is an integer of 1 or more.

Formula (2) B- (GA) _n -GB
General formula (3) C- (AG) _n -AC
A in the general formulas (2) and (3) is a divalent group derived from an alkylene dicarboxylic acid having 3 to 20 carbon atoms (preferably 4 to 12 carbon atoms), and has 4 to 20 carbon atoms (preferably 4 to 4 carbon atoms). 12) a divalent group derived from an alkenylene dicarboxylic acid or a divalent group derived from an aryl dicarboxylic acid having 8 to 20 carbon atoms (preferably 8 to 12).

  Examples of the divalent group derived from an alkylenedicarboxylic acid having 3 to 20 carbon atoms in A include 1,2-ethanedicarboxylic acid (succinic acid), 1,3-propanedicarboxylic acid (glutaric acid), 1 , 4-butanedicarboxylic acid (adipic acid), 1,5-pentanedicarboxylic acid (pimelic acid), 1,8-octanedicarboxylic acid (sebacic acid) and the like are included. Examples of the divalent group derived from alkenylene dicarboxylic acid having 4 to 20 carbon atoms in A include a divalent group derived from maleic acid, fumaric acid and the like. Examples of the divalent group derived from aryl dicarboxylic acid having 8 to 20 carbon atoms in A include 1,2-benzenedicarboxylic acid (phthalic acid), 1,3-benzenedicarboxylic acid, 1,4-benzene. Divalent groups derived from naphthalenedicarboxylic acid such as dicarboxylic acid and 1,5-naphthalenedicarboxylic acid are included.

  A may be one type or two or more types may be combined. Among these, A is preferably a combination of an alkylene dicarboxylic acid having 4 to 12 carbon atoms and an aryl dicarboxylic acid having 8 to 12 carbon atoms.

  G in the general formulas (2) and (3) is a divalent group derived from an alkylene glycol having 2 to 20 (preferably 2 to 12) carbon atoms, and has 6 to 20 (preferably 6 to 12) carbon atoms. ) Or a divalent group derived from an oxyalkylene glycol having 4 to 20 (preferably 4 to 12) carbon atoms.

  Examples of the divalent group derived from an alkylene glycol having 2 to 20 carbon atoms in G include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1, 3-butanediol, 1,2-propanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethyl-1,3-propanediol ( Neopentyl glycol), 2,2-diethyl-1,3-propanediol (3,3-dimethylolpentane), 2-n-butyl-2-ethyl-1,3-propanediol (3,3-dimethylol) Heptane), 3-methyl-1,5-pentanediol, 1,6-hexanediol, 2,2,4-trimethyl-1,3-pentanediol 2 derived from 2-ethyl-1,3-hexanediol, 2-methyl-1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-octadecanediol, and the like Valent groups are included.

  Examples of the divalent group derived from aryl glycol having 6 to 20 carbon atoms in G include 1,2-dihydroxybenzene (catechol), 1,3-dihydroxybenzene (resorcinol), 1,4-dihydroxybenzene. Divalent groups derived from (hydroquinone) and the like are included. Examples of the divalent group derived from oxyalkylene glycol having 4 to 12 carbon atoms in G are derived from diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol and the like. Divalent groups are included.

  G may be one type or two or more types may be combined. Especially, it is preferable that G is a C2-C12 alkylene glycol.

  B in the general formula (2) is a monovalent group derived from an aromatic ring-containing monocarboxylic acid or an aliphatic monocarboxylic acid.

  The aromatic ring-containing monocarboxylic acid in the monovalent group derived from the aromatic ring-containing monocarboxylic acid is a carboxylic acid containing an aromatic ring in the molecule, and not only those in which the aromatic ring is directly bonded to a carboxy group, Also included are those in which an aromatic ring is bonded to a carboxy group via an alkylene group. Examples of monovalent groups derived from aromatic ring-containing monocarboxylic acids include benzoic acid, para-tert-butyl benzoic acid, orthotoluic acid, metatoluic acid, p-toluic acid, dimethyl benzoic acid, ethyl benzoic acid, and normal propyl benzoic acid. Monovalent groups derived from aminobenzoic acid, acetoxybenzoic acid, phenylacetic acid, 3-phenylpropionic acid, and the like.

  Examples of monovalent groups derived from aliphatic monocarboxylic acids include monovalent groups derived from acetic acid, propionic acid, butanoic acid, caprylic acid, caproic acid, decanoic acid, dodecanoic acid, stearic acid, oleic acid and the like. Is included. Among these, a monovalent group derived from an alkyl monocarboxylic acid having 1 to 3 carbon atoms in the alkyl portion is preferable, and an acetyl group (a monovalent group derived from acetic acid) is more preferable.

  C in the general formula (3) is a monovalent group derived from an aromatic ring-containing monoalcohol or an aliphatic monoalcohol.

  An aromatic ring-containing monoalcohol is an alcohol containing an aromatic ring in the molecule, and includes not only those in which an aromatic ring is directly bonded to an OH group, but also those in which an aromatic ring is bonded to an OH group via an alkylene group or the like. . Examples of the monovalent group derived from an aromatic ring-containing monoalcohol include a monovalent group derived from benzyl alcohol, 3-phenylpropanol or the like.

  Examples of monovalent groups derived from aliphatic monoalcohols include methanol, ethanol, propanol, isopropanol, butanol, isobutanol, pentanol, isopentanol, hexanol, isohexanol, cyclohexyl alcohol, octanol, isooctanol, Monovalent groups derived from 2-ethylhexyl alcohol, nonyl alcohol, isononyl alcohol, tert-nonyl alcohol, decanol, dodecanol, dodecahexanol, dodecaoctanol, allyl alcohol, oleyl alcohol and the like are included. Of these, monovalent groups derived from alcohols having 1 to 3 carbon atoms such as methanol, ethanol, propanol, and isopropanol are preferable.

  The weight average molecular weight of the polycondensed ester is preferably in the range of 350 to 3000, and more preferably in the range of 400 to 1500. If the weight average molecular weight is within the above range, the precipitation of the polycondensation ester used in the present invention from the cellulose ester film can be satisfied, and the desired effect can be obtained. The weight average molecular weight can be measured by the gel permeation chromatography (GPC).

  Specific examples of the polycondensed ester are shown below. First, a specific example of a polycondensed ester in which both ends are sealed with an “aromatic group” is shown.

  Next, specific examples of the polycondensed ester in which both ends are sealed with an “aliphatic group” are shown below.

P-1: acetyl esterified product of both ends of a condensate (weight average molecular weight 950) composed of adipic acid / phthalic acid / ethanediol (1/1/2 molar ratio) P-2: succinic acid / phthalic acid / ethane Acetyl esterified product at both ends of a condensate (weight average molecular weight 2500) consisting of diol / (1/1/2 molar ratio) P-3: glutaric acid / isophthalic acid / 1,3-propanediol (1/1 / Acetyl esterified product of both ends of a condensate (weight average molecular weight 1300) consisting of 2 mole ratio) P-4: succinic acid / glutaric acid / adipic acid / terephthalic acid / isophthalic acid / ethanediol / 1,2-propanediol Propyl ester of both ends of a condensate (number average molecular weight 3000) consisting of (1/1/1/1/1/3/2 molar ratio) P-5: Succinic acid / phthalic acid / ethane Butyl esterified product of both ends of a condensate (weight average molecular weight 2100) consisting of diol / (1/1/2 molar ratio) P-6: adipic acid / terephthalic acid / 1,2-propanediol (1/1 / 2 mol ratio) 2-ethylhexyl esterified product of both ends of a condensate (number average molecular weight 2500) P-7: succinic acid / terephthalic acid / poly (average polymerization degree 5) propylene ether glycol / 1,2-propane 2-ethylhexyl esterified product of both ends of a condensate (weight average molecular weight 3500) composed of diol (2/1/1/2 molar ratio) P-8: adipic acid / phthalic acid / 1,2-propanediol (3 / 1/3 molar ratio) of the condensate (weight average molecular weight 490) at both ends is a benzoate ester The amount of the polycondensation ester added to the cellulose ester It is preferable to add in the range of 0.1 to 20% by mass, and more preferable to add in the range of 1 to 15% by mass from the viewpoint of improving the film hardness and film tear strength.

<Other plasticizers>
Examples of other plasticizers include polyhydric alcohol esters, polyhydric carboxylic acid esters (including phthalic acid esters), glycolate compounds, and fatty acid esters and phosphoric acid esters. These may be used alone or in combination of two or more.

  The polyhydric alcohol ester compound is an ester compound (alcohol ester) of a dihydric or higher aliphatic polyhydric alcohol and a monocarboxylic acid, preferably a 2-20 valent aliphatic polyhydric alcohol ester. The polyhydric alcohol ester compound preferably has an aromatic ring or a cycloalkyl ring in the molecule.

  Preferred examples of the aliphatic polyhydric alcohol include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propanediol, dipropylene glycol, tripropylene glycol, 1,2- Butanediol, 1,3-butanediol, 1,4-butanediol, dibutylene glycol, 1,2,4-butanetriol, 1,5-pentanediol, 1,6-hexanediol, hexanetriol, trimethylolpropane , Pentaerythritol, trimethylolethane, xylitol and the like. Of these, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, sorbitol, trimethylolpropane, xylitol and the like are preferable.

  The monocarboxylic acid is not particularly limited, and may be an aliphatic monocarboxylic acid, an alicyclic monocarboxylic acid, an aromatic monocarboxylic acid, or the like. In order to increase the moisture permeability of the film and make it less likely to volatilize, alicyclic monocarboxylic acids or aromatic monocarboxylic acids are preferred. One kind of monocarboxylic acid may be used, or a mixture of two or more kinds may be used. Further, all of the OH groups contained in the aliphatic polyhydric alcohol may be esterified, or a part of the OH groups may be left as they are.

  The aliphatic monocarboxylic acid is preferably a fatty acid having a straight chain or a side chain having 1 to 32 carbon atoms. The carbon number of the aliphatic monocarboxylic acid is more preferably 1-20, and still more preferably 1-10. Examples of aliphatic monocarboxylic acids include acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, 2-ethyl-hexanoic acid, undecylic acid, lauric acid, tridecylic acid , Saturated fatty acids such as myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, heptacosanoic acid, montanic acid, melicic acid, and laccelic acid; undecylenic acid, Examples include unsaturated fatty acids such as oleic acid, sorbic acid, linoleic acid, linolenic acid, and arachidonic acid. Of these, acetic acid or a mixture of acetic acid and other monocarboxylic acid is preferable in order to enhance the compatibility with cellulose acetate.

  Examples of the alicyclic monocarboxylic acid include cyclopentanecarboxylic acid, cyclohexanecarboxylic acid, cyclooctanecarboxylic acid and the like.

  Examples of aromatic monocarboxylic acids include benzoic acid; one having 1 to 3 alkyl groups or alkoxy groups (for example, methoxy group or ethoxy group) introduced into the benzene ring of benzoic acid (for example, toluic acid); benzene ring Aromatic monocarboxylic acids having two or more (for example, biphenyl carboxylic acid, naphthalene carboxylic acid, tetralin carboxylic acid, etc.) are included, and benzoic acid is preferred.

  Specific examples of the polyhydric alcohol ester compound include compounds described in paragraphs [0058] to [0061] of JP-A-2006-113239.

  The polyvalent carboxylic acid ester compound is an ester compound of a divalent or higher, preferably 2-20 valent polycarboxylic acid and an alcohol compound. The polyvalent carboxylic acid is preferably a 2-20 valent aliphatic polyvalent carboxylic acid, or a 3-20 valent aromatic polyvalent carboxylic acid or a 3-20 valent alicyclic polyvalent carboxylic acid. .

  Examples of polyvalent carboxylic acids include trivalent or higher aromatic polyvalent carboxylic acids or derivatives such as trimellitic acid, trimesic acid, pyromellitic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, oxalic acid Contains aliphatic polycarboxylic acids such as fumaric acid, maleic acid, and tetrahydrophthalic acid, and oxypolycarboxylic acids such as tartaric acid, tartronic acid, malic acid, and citric acid, and suppresses volatilization from the film. For this, oxypolycarboxylic acids are preferred.

  Examples of the alcohol compound include an aliphatic saturated alcohol compound having a straight chain or a side chain, an aliphatic unsaturated alcohol compound having a straight chain or a side chain, an alicyclic alcohol compound, or an aromatic alcohol compound. Carbon number of an aliphatic saturated alcohol compound or an aliphatic unsaturated alcohol compound becomes like this. Preferably it is 1-32, More preferably, it is 1-20, More preferably, it is 1-10. Examples of the alicyclic alcohol compound include cyclopentanol, cyclohexanol and the like. Examples of the aromatic alcohol compound include benzyl alcohol and cinnamyl alcohol.

  Although there is no restriction | limiting in particular in the molecular weight of a polyhydric carboxylic acid ester compound, It is preferable that it is the range of 300-1000, and it is more preferable that it is the range of 350-750. The molecular weight of the polyvalent carboxylic acid ester plasticizer is preferably larger from the viewpoint of suppressing bleeding out; it is preferably smaller from the viewpoint of moisture permeability and compatibility with cellulose acetate.

  Examples of polyvalent carboxylic acid ester compounds include triethyl citrate, tributyl citrate, acetyl triethyl citrate (ATEC), acetyl tributyl citrate (ATBC), benzoyl tributyl citrate, acetyl triphenyl citrate, acetyl tribenzyl citrate Rate, dibutyl tartrate, diacetyl dibutyl tartrate, tributyl trimellitic acid, tetrabutyl pyromellitic acid and the like.

  The polyvalent carboxylic acid ester compound may be a phthalic acid ester compound. Examples of the phthalate compound include diethyl phthalate, dimethoxyethyl phthalate, dimethyl phthalate, dioctyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate, dioctyl phthalate, dicyclohexyl phthalate, dicyclohexyl terephthalate and the like.

  Examples of glycolate compounds include alkylphthalyl alkyl glycolates. Examples of alkyl phthalyl alkyl glycolates include methyl phthalyl methyl 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, methyl phthalyl butyl glycolate, ethyl phthalyl butyl glycolate, butyl phthalyl methyl glycolate, butyl phthalyl ethyl glycolate, propyl phthalyl butyl Glycolate, butyl phthalyl propyl glycolate, methyl phthalyl octyl glycolate, ethyl phthalyl octyl glycolate, octyl phthalyl methyl glycolate, octyl phthalyl ethyl Glycolate and the like, preferably ethyl phthalyl ethyl glycolate.

  The ester compound includes a fatty acid ester compound, a citrate ester compound, a phosphate ester compound, and the like.

  Examples of the fatty acid ester compound include butyl oleate, methylacetyl ricinoleate, and dibutyl sebacate. Examples of the citrate ester compound include acetyltrimethyl citrate, acetyltriethyl citrate, and acetyltributyl citrate. Examples of the phosphoric acid ester compound include triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, biphenyl diphenyl phosphate, trioctyl phosphate, tributyl phosphate, etc., preferably triphenyl phosphate. .

  Of these, polyester compounds, glycolate compounds, and phosphate ester compounds are preferable, and polyester compounds are particularly preferable.

  The content of the plasticizer is preferably in the range of 1 to 20% by mass and more preferably in the range of 1.5 to 15% by mass with respect to the cellulose acetate. When the content of the plasticizer is within the above range, an effect of imparting plasticity can be exhibited, and since the plasticizer has excellent anti-bleeding resistance, the deviation of the contact angle on the film surface can be reduced.

<Antioxidant>
Antioxidants are also referred to as deterioration inhibitors. When a liquid crystal image display device or the like is placed in a high humidity and high temperature state, the cellulose ester film may be deteriorated.

  The antioxidant has a role of delaying or preventing the cellulose ester film from being decomposed by, for example, a residual solvent amount of halogen in the cellulose ester film or phosphoric acid of a phosphoric acid plasticizer. It is preferable to make it contain in.

  As such an antioxidant, a hindered phenol compound is preferably used. For example, 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-tert-butyl-4-hydroxyphenyl) propionate], octa Sil-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) benzene, tris- (3,5-di-t-butyl-4-hydroxy Benzyl) -isocyanurate and the like.

  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- A phosphorus processing stabilizer such as t-butylphenyl) phosphite may be used in combination.

  The addition amount of these compounds is preferably in the range of 1 ppm to 1.0% by mass ratio with respect to the cellulose ester, and more preferably in the range of 10 to 1000 ppm.

<Fine particles (matting agent)>
The cellulose ester film of the present invention may further contain fine particles (matting agent) as necessary in order to enhance the slipperiness of the surface.

  The fine particles may be inorganic fine particles or organic fine particles. Examples of inorganic fine particles include silicon dioxide (silica), titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, Examples include magnesium silicate and calcium phosphate. Of these, silicon dioxide and zirconium oxide are preferable, and silicon dioxide is more preferable in order to reduce the increase in haze of the obtained film.

  Examples of the fine particles of silicon dioxide include Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, TT600, NAX50 (manufactured by Nippon Aerosil Co., Ltd.), Seahoster KE-P10, KE-P30, KE-P50, KE-P100 (manufactured by Nippon Shokubai Co., Ltd.) and the like are included. Of these, Aerosil R972V, NAX50, Seahoster KE-P30 and the like are particularly preferable because they reduce the coefficient of friction while keeping the turbidity of the resulting film low.

  The primary particle diameter of the fine particles is preferably in the range of 5 to 50 nm, and more preferably in the range of 7 to 20 nm. A larger primary particle size has a greater effect of increasing the slipperiness of the resulting film, but transparency tends to decrease. Therefore, the fine particles may be contained as secondary aggregates having a particle diameter in the range of 0.05 to 0.3 μm. The size of the primary particles or the secondary aggregates of the fine particles was observed with a transmission electron microscope at a magnification of 500,000 to 2,000,000 times, and the primary particles or secondary aggregates were observed. It can be determined as an average value of the particle diameter.

  The content of the fine particles is preferably in the range of 0.05 to 1.0% by mass and preferably in the range of 0.1 to 0.8% by mass with respect to the whole cellulose acetate including the low substitution degree component. More preferred.

≪Method for producing cellulose ester film≫
As a method for producing the cellulose ester film of the present invention, production methods such as a normal inflation method, a T-die method, a calendar method, a cutting method, a casting method, an emulsion method, and a hot press method can be used. From the viewpoint of suppression of foreign matter defects, suppression of optical defects such as die lines, etc., a film casting method can be selected from a solution casting film forming method and a melt casting film forming method, and in particular, a solution casting film forming method, It is preferable from the viewpoint that a uniform and smooth surface can be obtained.

  Hereinafter, the manufacture example which manufactures the cellulose-ester film of this invention with a solution casting method is demonstrated.

  In the production of the cellulose ester film of the present invention, at least a cellulose ester, a nitrogen-containing heterocyclic compound that is a retardation increasing agent, and an additive are dissolved in a solvent to prepare a dope, and the step of filtering is performed. After casting on a drum-shaped metal support to form a web, peeling the formed web from the metal support to form a film, stretching and drying the film, and after cooling the dried film It is performed by a step of winding in a roll shape. The cellulose ester film of the present invention preferably contains cellulose ester in the range of 60 to 95% by mass in the solid content.

  The method for producing a cellulose ester film of the present invention is characterized in that, in the step, a leaf disk filter is used at a temperature within the range of (boiling point + 5 ° C.) to (boiling point + 20 ° C.) at 1 atmosphere of the main solvent of the dope. And the film is stretched at a stretching speed of 250 to 500% / min in the width direction of the film within the range of 2 to 10% by mass of the residual solvent.

  By adopting such a manufacturing method, the deviation of the contact angle on the surface of the cellulose ester film is reduced, and the spreadability of the water glue or the UV curable adhesive is improved to achieve uniform adhesion with the polarizer. Is.

  Hereinafter, each step will be described.

(1) Dissolution step In an organic solvent mainly composed of a good solvent for cellulose ester, the cellulose ester in a dissolution vessel, and in some cases, the nitrogen-containing heterocyclic compound according to the present invention, the sugar ester used in the present invention, and the polycondensation ester , A step of dissolving a polyhydric alcohol ester or other compound with stirring to form a dope, or adding the nitrogen-containing heterocyclic compound, sugar ester, polycondensed ester, polyhydric alcohol ester, or the like to the cellulose ester solution. The dope which is a main solution is formed by mixing the compound solution.

  When the cellulose ester film of the present invention is produced by a solution casting method, an organic solvent useful for forming a dope can be used without limitation as long as it dissolves cellulose ester and other compounds simultaneously.

  For example, as the chlorinated organic solvent, methylene chloride, as the non-chlorinated organic solvent, methyl acetate, ethyl acetate, amyl acetate, acetone, tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, cyclohexanone, ethyl formate, 2,2,2-trifluoroethanol, 2,2,3,3-hexafluoro-1-propanol, 1,3-difluoro-2-propanol, 1,1,1,3,3,3-hexafluoro- Examples include 2-methyl-2-propanol, 1,1,1,3,3,3-hexafluoro-2-propanol, 2,2,3,3,3-pentafluoro-1-propanol, and nitroethane. For example, methylene chloride, methyl acetate, ethyl acetate, acetone can be preferably used as the main solvent, methylene chloride or Particularly preferably ethyl.

  In addition to the organic solvent, the dope preferably contains a linear or branched aliphatic alcohol having 1 to 4 carbon atoms in the range of 1 to 40% by mass. When the proportion of alcohol in the dope increases, the web gels and peeling from the metal support becomes easy. When the proportion of alcohol is small, cellulose ester and other compounds dissolve in non-chlorine organic solvents. There is also a role to promote. In the film formation of the cellulose ester film of the present invention, a method of forming a film using a dope having an alcohol concentration in the range of 0.5 to 15.0% by mass from the viewpoint of enhancing the flatness of the obtained cellulose ester film. Can be applied.

  In particular, a dope composition in which cellulose ester and other compounds are dissolved in a total amount of 15 to 45% by mass in a solvent containing methylene chloride and a linear or branched aliphatic alcohol having 1 to 4 carbon atoms. It is preferable that it is a thing.

  Examples of the linear or branched aliphatic alcohol having 1 to 4 carbon atoms include methanol, ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol, and tert-butanol. Methanol and ethanol are preferred because of the stability, boiling point of these inner dopes, and good drying properties.

  Cellulose ester, nitrogen-containing heterocyclic compound, sugar ester, polycondensation ester, polyhydric alcohol ester, or other compounds are dissolved at normal pressure, below the boiling point of the main solvent, or at the boiling point of the main solvent. The method of pressurizing as described above, the method of performing the cooling dissolution method as described in JP-A-9-95544, JP-A-9-95557, or JP-A-9-95538, JP-A-11-21379 Various dissolution methods such as the method performed at a high pressure described in the above can be used, but the method performed by pressurizing at a boiling point or higher of the main solvent is particularly preferable.

  The concentration of the cellulose ester in the dope is preferably in the range of 10 to 40% by mass. After the compound is added to the dope during or after dissolution and dissolved and dispersed, it is filtered through a filter medium, defoamed, and sent to the next step with a liquid feed pump.

  In the present invention, the dope is filtered at a temperature within the range of (boiling point + 5 ° C.) to (boiling point + 20 ° C.) at 1 atm of the main solvent in the dope, thereby removing fine foreign matters and precipitates in the dope. It can be removed and is preferred.

  A preferable temperature range is 45 to 120 ° C, more preferably 45 to 70 ° C, and still more preferably 45 to 55 ° C. For example, since the boiling point of methylene chloride is 40 ° C. under 1 atm, it is preferably in the range of 45-60 ° C.

  For dope filtration, the dope is preferably filtered by a main filter 3 having a leaf disk filter, for example, with a filter medium having a 90% collection particle diameter of 10 to 100 times the average particle diameter of the fine particles.

  In the present invention, the filter medium used for filtration preferably has a low absolute filtration accuracy. However, if the absolute filtration accuracy is too small, the filter medium is likely to be clogged, and the filter medium must be frequently replaced. There is a problem of lowering productivity.

  For this reason, in the present invention, the filter medium used for the cellulose ester dope preferably has an absolute filtration accuracy of 0.008 mm or less, more preferably in the range of 0.001 to 0.008 mm, and 0.003 to 0.006 mm. A range of filter media is more preferred.

  There are no particular restrictions on the material of the filter medium, and normal filter media can be used. However, plastic fiber filter media such as polypropylene and Teflon (registered trademark), and metal filter media such as stainless steel fibers are used to remove fibers. This is preferable.

In the present invention, the dope flow rate during filtration is preferably 10 to 80 kg / (h · m ² ), more preferably 20 to 60 kg / (h · m ² ). Here, if the flow rate of the dope at the time of filtration is 10 kg / (h · m ² ) or more, it becomes efficient productivity, and the flow rate of the dope at the time of filtration is within 80 kg / (h · m ² ). If so, the pressure applied to the filter medium is appropriate, and the filter medium is not damaged, which is preferable.

  The filtration pressure is preferably 3500 kPa or less, more preferably 3000 kPa or less, and even more preferably 2500 kPa or less. The filtration pressure can be controlled by appropriately selecting the filtration flow rate and the filtration area.

  FIG. 1 is a diagram schematically showing an example of a dope preparation step, a casting step, and a drying step of a solution casting film forming method preferable for the present invention.

  Large agglomerates are removed from the charging kettle 41 by the filter 44 and fed to the stock kettle 42. Thereafter, various additive solutions are added from the stock kettle 42 to the main dope dissolving kettle 1.

  Thereafter, the main dope is filtered by the main filter 3, and a matting agent dispersion, an ultraviolet absorber addition liquid, and the like are added thereto in-line from 16.

  In many cases, the main dope may contain about 10 to 50% by mass of the recycled material.

  A recycled material is a finely pulverized cellulose ester film that is produced when a cellulose ester film is formed. Film stock is used.

  Moreover, as a raw material of resin used for dope preparation, what pelletized cellulose ester and other compounds previously can be used preferably.

(2) Casting step (2-1) Casting of dope An endless metal support 31 that feeds the dope to the pressurizing die 30 through a feed pump (for example, a pressurization type metering gear pump) and transfers it infinitely, For example, a dope is cast from a pressure die slit at a casting position on a metal support such as a stainless steel belt or a rotating metal drum.

  The metal support in the casting (casting) step preferably has a mirror-finished surface, and a stainless steel belt or a drum whose surface is plated with a casting is preferably used as the metal support. The cast width can be in the range of 1 to 4 m, preferably in the range of 1.5 to 3 m, and more preferably in the range of 2 to 2.8 m. The surface temperature of the metal support in the casting step is set in the range of −50 ° C. to a temperature at which the solvent boils and does not foam, more preferably in the range of −30 to 0 ° C. A higher temperature is preferable because the web can be dried faster, but if it is too high, the web may foam or the flatness may deteriorate. A preferable support temperature is appropriately determined at 0 to 100 ° C, and more preferably 5 to 30 ° C. Alternatively, it is also a preferable method that the web is gelled by cooling and peeled from the drum in a state containing a large amount of residual solvent. The method for controlling the temperature of the metal support is not particularly limited, and there are a method of blowing warm air or cold air, and a method of contacting hot water with the back side of the metal support. It is preferable to use warm water because heat transfer is performed efficiently, so that the time until the temperature of the metal support becomes constant is short. When using warm air, considering the temperature drop of the web due to the latent heat of vaporization of the solvent, while using warm air above the boiling point of the solvent, there may be cases where wind at a temperature higher than the target temperature is used while preventing foaming. . In particular, it is preferable to perform drying efficiently by changing the temperature of the support and the temperature of the drying air during the period from casting to peeling.

  A pressure die that can adjust the slit shape of the die base portion and can easily make the film thickness uniform is preferable. Examples of the pressure die include a coat hanger die and a T die, and any of them is preferably used. The surface of the metal support is a mirror surface. In order to increase the film forming speed, two or more pressure dies may be provided on the metal support, and the dope amount may be divided and laminated.

(3) Solvent evaporation step The web (the dope is cast on the casting support and the formed dope film is referred to as a web) is heated on the casting support to evaporate the solvent.

  To evaporate the solvent, there are a method of blowing air from the web side, a method of transferring heat from the back side of the support, a method of transferring heat from the front and back by radiant heat, etc. Is preferable. A method of combining them is also preferably used. The web on the support after casting is preferably dried on the support in an atmosphere of 40 to 100 ° C. In order to maintain the atmosphere at 40 to 100 ° C., it is preferable to apply hot air at this temperature to the upper surface of the web or to heat by means such as infrared rays.

  From the viewpoint of surface quality, moisture permeability, and peelability, it is preferable to peel the web from the support within 30 to 120 seconds.

(4) Peeling process It is the process of peeling the web which the solvent evaporated on the metal support body in a peeling position. The peeled web is sent to the next process as a film.

  The temperature at the peeling position on the metal support is preferably in the range of 10 to 40 ° C, more preferably in the range of 11 to 30 ° C.

  In addition, it is preferable that the residual solvent amount at the time of peeling of the web on the metal support at the time of peeling is peeled in the range of 50 to 120% by mass depending on the strength of drying conditions, the length of the metal support, and the like. When peeling at a higher residual solvent amount, if the web is too soft, the flatness at the time of peeling is impaired, and slippage and vertical stripes are likely to occur due to the peeling tension. The amount of solvent is determined.

  The residual solvent amount of the web is defined by the following formula (Z).

Formula (Z)
Residual solvent amount (%) = (mass before web heat treatment−mass after web heat treatment) / (mass after web heat treatment) × 100
Note that the heat treatment for measuring the residual solvent amount represents performing heat treatment at 115 ° C. for 1 hour.

  The peeling tension when peeling the metal support from the film is usually in the range of 196 to 245 N / m. However, when wrinkles are likely to occur during peeling, peeling with a tension of 190 N / m or less is preferable. .

  In the present invention, the temperature at the peeling position on the metal support is preferably in the range of −50 to 40 ° C., more preferably in the range of 10 to 40 ° C., and in the range of 15 to 30 ° C. Is most preferred.

(5) Drying and stretching step The drying step can be divided into a preliminary drying step and a main drying step.

<Preliminary drying process>
The web obtained by peeling from the metal support is dried. The web may be dried while being conveyed by a large number of rollers arranged above and below, or may be dried while being conveyed while fixing both ends of the web with clips like a tenter dryer. .

  The means for drying the web is not particularly limited and can be generally performed with hot air, infrared rays, a heating roller, microwaves, or the like, but it is preferably performed with hot air in terms of simplicity.

The drying temperature in the web drying step is preferably a glass transition point of the film of −5 ° C. or less, and it is effective to perform a heat treatment at 100 ° C. or more and 10 minutes or more and 60 minutes or less. Drying is performed at a drying temperature in the range of 100 to 200 ° C, more preferably in the range of 110 to 160 ° C. <Extension process>
The cellulose ester film of the present invention can be subjected to stretching treatment to control the orientation of molecules in the film, and target retardation values Re and Rth can be obtained.

  The cellulose ester film of the present invention is preferably stretched in the casting direction (also referred to as MD direction) and / or in the width direction (also referred to as TD direction), and is stretched in the width direction by at least a tenter stretching device. It is preferable to manufacture.

  The stretching operation may be performed in multiple stages. When biaxial stretching is performed, simultaneous biaxial stretching may be performed or may be performed stepwise. In this case, stepwise means that, for example, stretching in different stretching directions can be sequentially performed, stretching in the same direction is divided into multiple stages, and stretching in different directions is added to any one of the stages. Is also possible.

Thus, for example, the following stretching steps are possible:
-Stretch in the casting direction-> Stretch in the width direction-> Stretch in the casting direction-> Stretch in the casting direction-Stretch in the width direction-> Stretch in the width direction-> Stretch in the casting direction-> Stretch in the casting direction Simultaneous biaxial stretching includes stretching in one direction and contracting the other while relaxing the tension.

  In particular, the stretching speed represented by the following formula 3 in the width direction of the film may be stretched at a stretching speed of 250 to 500% / min in the range of 2 to 10% by mass of the residual solvent at the start of stretching. It is preferable because minute foreign substances and precipitates are prevented from moving and diffusing to the film surface by stretching, and the deviation of the contact angle on the film surface is reduced.

  The amount of residual solvent at the start of stretching is a factor that affects the level of stretching stress.If the amount of residual solvent is large, the stretching stress decreases, and fine foreign substances and precipitates easily move to the film surface by stretching. When the residual solvent amount is small, the stretching stress increases, and haze is generated due to stretching.

  If the amount of the residual solvent is 2% by mass or more, the film thickness deviation is small and is preferable from the viewpoint of flatness, and if it is within 10% by mass, the surface unevenness is reduced, and the flatness is improved. The cellulose ester film of the present invention has a (Tg + 15) when the glass transition temperature of the film is defined as Tg in the MD direction and / or TD direction, preferably in the TD direction so that the film thickness after stretching is in a desired range. ) To (Tg + 50) It is preferable to stretch in the temperature range. If the stretching is performed within the above temperature range, the retardation can be easily adjusted, and the stretching stress can be reduced, so that the haze is lowered. Moreover, generation | occurrence | production of a fracture | rupture is suppressed and the cellulose ester film excellent in planarity and the coloring property of the film itself is obtained. The stretching temperature is preferably in the range of (Tg + 20) to (Tg + 40) ° C.

  In addition, the glass transition temperature Tg here is measured at a temperature rising rate of 20 ° C./min using a commercially available differential scanning calorimeter, and is determined at an intermediate glass transition temperature (Tmg) determined according to JIS K7121 (1987). It is. The measuring method of the glass transition temperature Tg of a specific cellulose ester film is measured using a differential scanning calorimeter DSC220 manufactured by Seiko Instruments Inc. according to JIS K7121 (1987).

  The cellulose ester film of the present invention preferably stretches the web at least 1.1 times in the TD direction. The range of stretching is preferably 1.1 to 1.5 times the original width, and more preferably 1.2 to 1.4 times. Within the above range, the movement of molecules in the film is large, and not only a desired retardation value can be obtained, but also the film can be thinned and the deviation of the contact angle on the film surface can be reduced.

  In order to stretch in the MD direction, it is preferable to peel at a peeling tension of 130 N / m or more, and particularly preferably 150 to 170 N / m. Since the web after peeling is in a high residual solvent state, stretching in the MD direction can be performed by maintaining the same tension as the peeling tension. As the web dries and the residual solvent amount decreases, the stretch ratio in the MD direction decreases.

  The draw ratio in the MD direction can be calculated from the rotation speed of the belt support and the tenter operation speed.

  In order to stretch in the TD direction, for example, the entire drying process or a part of the process as disclosed in Japanese Patent Application Laid-Open No. 62-46625 is performed while holding the width at both ends of the web with clips or pins in the width direction. A drying method (referred to as a tenter method), among them, a tenter method using clips and a pin tenter method using pins are preferably used.

  When stretching in the TD direction, the stretching rate represented by the following formula 3 is stretched in the width direction of the film at a stretching rate in the range of 250 to 500% / min. It is preferable because it can suppress movement and diffusion to the surface and can reduce the deviation of the contact angle on the film surface. This is presumed that when stretching is performed at a relatively high stretching speed, fine foreign matter does not appear on the surface, but stretching is performed, and the standard deviation of contact angle or the occurrence of unevenness is improved.

Formula 3 Stretching speed (% / min) = [(d1 / d2) -1] × 100 (%) / t
(In Formula 3, d1 is the width dimension in the stretching direction of the cellulose acylate film after stretching, d2 is the width dimension in the stretching direction of the cellulose acylate film before stretching, and t is the time required for stretching ( min).)
If the stretching speed is 250% / min or more, the planarity is improved and the film can be processed at a high speed, which is preferable from the viewpoint of production aptitude, and if it is within 500% / min, the film is broken. Can be processed without any problem.

  A preferable stretching speed is in the range of 300 to 400% / min.

  The cellulose ester film of the present invention inevitably has a phase difference by stretching, but the in-plane retardation value Re and the retardation value Rth in the thickness direction are measured by an automatic birefringence meter Axoscan (Axo Scan Mueller Matrix Polarimeter). : Manufactured by Axometrics Co., Ltd.) under the environment of 23 ° C. and 55% RH at a wavelength of 590 nm, the three-dimensional refractive index measurement can be performed, and the obtained refractive indexes nx, ny and nz can be calculated.

  The cellulose ester film of the present invention has a retardation value Re in the in-plane direction of the cellulose ester film represented by the following formula (i) within a range of 45 to 60 nm, and a film thickness represented by the following formula (ii). When the retardation value Rth in the direction is in the range of 110 to 140 nm, it is preferable from the viewpoint of improving the visibility such as the viewing angle and the contrast when the VA mode liquid crystal display device is provided. The cellulose ester film can be adjusted within the above retardation value by stretching at least while adjusting the stretching ratio in the TD direction.

Formula _{(i): Re = (n} x -n y) × d (nm)
Formula (ii): Rth = {(n _x + n _y ) / 2−n _z } × d (nm)
In (formula (i) and Formula (ii), n _x is .n _y representing the refractive index in the direction x in which the refractive index is maximized in the plane direction of the film in-plane direction of the film, the direction x Represents the refractive index in the direction y orthogonal to _nz , _nz represents the refractive index in the thickness direction z of the film, and d represents the thickness (nm) of the film.)
<Knurling>
After a predetermined heat treatment or cooling treatment, it is preferable to provide a slitter and cut off the end portion before winding to obtain a good winding shape. Furthermore, it is preferable to knurling both ends of the width.

  The knurling process can be formed by pressing a heated embossing roller. Fine embossing is formed on the embossing roller, and by pressing the embossing roller, unevenness can be formed on the film and the end can be made bulky.

  The height of the knurling at both ends of the width of the retardation film of the present invention is preferably 4 to 20 μm and a width of 5 to 20 mm.

  In the present invention, the knurling process is preferably provided after the drying in the film forming process and before winding.

(6) Winding step This is a step of winding as a film after the residual solvent amount in the web is 2% by mass or less, and the film having good dimensional stability by making the residual solvent amount 0.4% by mass or less. Can be obtained.

  As a winding method, a generally used method 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, etc., and these may be used properly.

[Physical properties of cellulose ester film]
(Haze)
The cellulose ester film of the present invention preferably has a haze of less than 1%, more preferably less than 0.5%, and even more preferably less than 0.3%. By setting the haze to less than 1%, there is an advantage that the transparency of the film becomes higher and it becomes easier to use as a film for optical applications. Moreover, the internal haze of the cellulose ester film is preferably less than 0.1, and more preferably less than 0.05.

(Equilibrium moisture content)
The cellulose ester film of the present invention preferably has an equilibrium water content of 4% or less at 25 ° C. and a relative humidity of 60%, more preferably 3% or less. By setting the equilibrium moisture content to 4% or less, it is preferable to easily cope with a change in humidity and to hardly change the optical characteristics and dimensions.

(Film length, width, film thickness)
The cellulose ester film of the present invention is preferably long, specifically, preferably has a length of about 100 to 10000 m, and is wound into a roll. The width of the cellulose ester film of the present invention is preferably 1 m or more, more preferably 1.4 m or more, and particularly preferably 1.4 to 4 m.

  The film thickness is preferably in the range of 10 to 38 μm from the viewpoint of thinning the display device and productivity. If the film thickness is 10 μm or more, a certain level of film strength and retardation can be expressed. If the film thickness is 38 μm or less, it has a desired phase difference and can be applied to thin the polarizing plate and the display device. From the comprehensive viewpoints such as production suitability as a cellulose ester film, optical properties, physical properties, preservability during roll storage, and handleability during polarizing plate processing, the film thickness is particularly preferably in the range of 20 to 38 μm. .

≪Polarizing plate≫
In the polarizing plate of the present invention, it is preferable that the cellulose ester film of the present invention is bonded to at least one surface of a polarizer using a water paste or an ultraviolet curable adhesive.

  In addition, a polyester film or an acrylic film is bonded to the polarizer using water glue or an ultraviolet curable adhesive on the surface of the polarizer opposite to the surface on which the cellulose ester film is bonded. If so, it is a preferred embodiment because the variation in retardation of the cellulose ester film with respect to humidity is further reduced.

  When the polarizing plate of the present invention is used as a viewing side polarizing plate, the viewing side film of the polarizing plate is provided with an antiglare layer or a clear hard coat layer, an antireflection layer, an antistatic layer, an antifouling layer, and the like. Is preferred.

[Polarizer]
The polarizer, which is the main component of the polarizing plate of the present invention, is an element that passes only light having a plane of polarization in a certain direction, and a typical known polarizer is a polyvinyl alcohol polarizing film. The polyvinyl alcohol polarizing film includes those obtained by dyeing iodine on a polyvinyl alcohol film and those obtained by dyeing a dichroic dye.

  As the polarizer, a polarizer obtained by forming a polyvinyl alcohol aqueous solution into a film and dyeing it by uniaxial stretching or dyeing and then uniaxially stretching and then preferably performing a durability treatment with a boron compound may be used. The film thickness of the polarizer is preferably 2 to 30 μm, particularly preferably 2 to 15 μm.

  Further, the ethylene unit content described in JP-A-2003-248123, JP-A-2003-342322, etc. is 1 to 4 mol%, the degree of polymerization is 2000 to 4000, and the degree of saponification is 99.0 to 99.99 mol%. The ethylene-modified polyvinyl alcohol is also preferably used. Among these, an ethylene-modified polyvinyl alcohol film having a hot water cutting temperature of 66 to 73 ° C. is preferably used. A polarizer using this ethylene-modified polyvinyl alcohol film is excellent in polarization performance and durability, and has little color unevenness, and is particularly preferably used for a large liquid crystal display device.

<Laminated film type polarizer>
In addition, the polarizing plate of the present invention is preferably a thin film, and the thickness of the polarizer is particularly preferably in the range of 2 to 15 μm from the viewpoint of achieving both the strength of the polarizing plate and the thinning.

  As such a thin film polarizer, a laminated film type polarizer is produced by the method described in JP2011-1000016, JP4691205, JP4751481, JP48080489. Is preferred.

  As an example, it is preferable to use a thin film laminated film type polarizer (polarizing laminated film) manufactured by the following steps from the viewpoint of reducing the overall thickness of the polarizing plate and reducing the weight.

(Production method of polarizing laminated film)
The manufacturing method of the light-polarizing laminated film used for this invention includes the following process.
(A) a laminating step of obtaining a laminated film by forming a polyvinyl alcohol-based resin layer on one surface of a base film in which a rubber component is dispersed in a thermoplastic resin;
(B) A stretching process for uniaxially stretching the laminated film to obtain a stretched film;
(C) a dyeing process of obtaining a dyed film by dyeing a polyvinyl alcohol resin layer of a stretched film with a dichroic dye;
(D) The polyvinyl alcohol resin layer of the dyed film is immersed in a solution containing a crosslinking agent to form a polarizer layer, and a crosslinking step for obtaining a crosslinked film; and (e) a drying step for drying the crosslinked film. Explaining the process,
(A) Laminating step In this step, a film obtained by dispersing (blending) a rubber component in a thermoplastic resin is used as a base film, and a polyvinyl alcohol resin layer is formed on one surface to obtain a laminated film. Is preferred.

(1) Base film The thermoplastic resin that is the base of the base film is preferably a thermoplastic resin that is excellent in transparency, mechanical strength, thermal stability, stretchability, and the like. Specific examples of such a thermoplastic resin include, for example, a chain polyolefin resin; a cyclic polyolefin resin; a (meth) acrylic resin; a polyester resin; a cellulose ester resin; a polycarbonate resin; and a polyvinyl alcohol resin. A vinyl acetate resin; a polyarylate resin; a polystyrene resin; a polyethersulfone resin; a polysulfone resin; a polyamide resin; a polyimide resin; and a mixture or copolymer thereof.

  The rubber component dispersed in the thermoplastic resin is a resin component having rubber elasticity, and is usually uniformly dispersed in the thermoplastic resin as rubber particles. By mixing and dispersing the rubber component, it is possible to improve the tear strength of the base film and thus the stretched film. The rubber component is not particularly limited as long as it is a resin having rubber elasticity. However, from the viewpoint of compatibility with the thermoplastic resin, the rubber component is preferably composed of the same or similar resin as the thermoplastic resin to be used.

  For example, when the thermoplastic resin is a chain polyolefin-based resin, the rubber component can be a copolymer of two or more monomers selected from ethylene and α-olefin. In this case, the content (polymerization ratio) of each monomer constituting the copolymer is preferably less than 90% by mass, and more preferably less than 80% by mass.

  When the thermoplastic resin is a (meth) acrylic resin, it is preferable to contain an acrylic polymer having rubber elasticity as a rubber component from the viewpoint of compatibility. The acrylic polymer is preferably a polymer mainly composed of alkyl acrylate, and may be a homopolymer of alkyl acrylate, or 50% by mass or more of alkyl acrylate and 50% by mass or less of other monomers. And a copolymer thereof.

  The compounding amount of the rubber component is preferably 5 to 50% by mass of the thermoplastic resin, more preferably 10 to 45% by mass. When the blending amount of the rubber component is too small, it is difficult to obtain a sufficient effect of improving the tear strength, and when the blending amount of the rubber component is too large, the handleability of the base film tends to be lowered.

  The method for dispersing the rubber component in the thermoplastic resin is not particularly limited. For example, the thermoplastic resin and rubber component (rubber particles) produced separately are kneaded and dispersed with a plastmill or the like, or the same reaction when preparing the thermoplastic resin. Examples thereof include a reactor blend method in which a rubber component is also prepared in a container to obtain a thermoplastic resin in which the rubber component is dispersed. The reactor blending method is advantageous in improving the degree of dispersion of the rubber component.

(2) Polyvinyl alcohol-type resin layer As a polyvinyl alcohol-type resin which forms a polyvinyl alcohol-type resin layer, a polyvinyl alcohol resin and its derivative (s) are mentioned, for example. Derivatives of polyvinyl alcohol resin include polyvinyl formal, polyvinyl acetal, etc., olefins such as ethylene and propylene, unsaturated carboxylic acids such as acrylic acid, methacrylic acid and crotonic acid, and alkyl esters of unsaturated carboxylic acids. And those modified with acrylamide or the like. Among these, it is preferable to use a polyvinyl alcohol resin.

  The polyvinyl alcohol resin is preferably a completely saponified product. The range of the saponification degree is preferably in the range of 80.0 to 100.0 mol%, more preferably in the range of 90.0 to 99.5 mol%, still more preferably 94.0 to 99.0. It is in the range of mol%.

  If necessary, additives such as a plasticizer and a surfactant may be added to the polyvinyl alcohol-based resin described above. As the plasticizer, polyols and condensates thereof can be used, and examples thereof include glycerin, diglycerin, triglycerin, ethylene glycol, propylene glycol, and polyethylene glycol. Although the compounding quantity of an additive is not restrict | limited in particular, It is suitable to set it as 20 mass% or less of a polyvinyl alcohol-type resin.

  As a method for coating a polyvinyl alcohol resin solution on a base film, a wire bar coating method, a roll coating method such as reverse coating or gravure coating, a spin coating method, a screen coating method, a fountain coating method, a dipping method, or a spray method. It can select suitably from well-known methods, such as. A drying temperature is the range of 50-200 degreeC, for example, Preferably it is the range of 60-150 degreeC. The drying time is, for example, in the range of 2 to 20 minutes.

  The thickness of the polyvinyl alcohol resin layer in the laminated film is preferably 3 μm or more and 50 μm or less, and more preferably 5 μm or more and 45 μm or less. If it is 3 μm or less, it becomes too thin after stretching and the dyeability is significantly deteriorated. If it exceeds 50 μm, the resulting polarizing laminate film becomes thick.

  The thickness of the polyvinyl alcohol-based resin layer as a polarizer used in the present invention is within the range of 2 to 15 μm as the film thickness after the following stretching treatment from the viewpoint of thinning, strength as a polarizer, and flexibility. Is preferred.

(B) Stretching step This step is a step of obtaining a stretched film by uniaxially stretching a laminated film including a base film and a polyvinyl alcohol-based resin layer. The draw ratio of the laminated film can be appropriately selected according to the desired polarization characteristics, but is preferably in the range of 5 to 17 times, more preferably 5 to 8 times the original length of the laminated film. Within range.

  The stretching is preferably longitudinal stretching in which stretching is performed in the longitudinal direction (film transport direction) of the laminated film. Examples of the longitudinal stretching method include an inter-roller stretching method, a compression stretching method, and a stretching method using a tenter. The uniaxial stretching is not limited to the longitudinal stretching process, and may be oblique stretching or the like.

(C) Dyeing step This step is a step of obtaining a dyed film by dyeing the polyvinyl alcohol resin layer of the stretched film with a dichroic dye. Examples of the dichroic dye include iodine and organic dyes. Examples of organic dyes include Red BR, Red LR, Red R, Pink LB, Rubin BL, Bordeaux GS, Sky Blue LG, Lemon Yellow, Blue BR, Blue 2R, Navy RY, Green LG, Violet LB, Violet B, Black H, Black B, Black GSP, Yellow 3G, Yellow R, Orange LR, Orange 3R, Scarlet GL, Scarlet KGL, Congo Red, Brilliant Violet BK, Spura Blue G, Spura Blue GL, Spura Orange GL, Direct Sky Blue, Direct First Orange S, First Black, etc. can be used. These dichroic substances may be used alone or in combination of two or more.

  When iodine is used as the dichroic dye, it is preferable to further add iodide to the dyeing solution containing iodine because the dyeing efficiency can be further improved. Examples of the iodide include potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide, and iodide. Examples include titanium.

(D) Crosslinking step In this step, the polyvinyl alcohol resin layer of the dyed film obtained by dyeing with a dichroic dye is subjected to a crosslinking treatment, and a crosslinked film using the polyvinyl alcohol resin layer as a polarizer layer is obtained. It is a process to obtain. The crosslinking step can be performed, for example, by immersing the dyed film in a solution containing a crosslinking agent (crosslinking solution). Conventionally known substances can be used as the crosslinking agent. Examples thereof include boron compounds such as boric acid and borax, glyoxal, and glutaraldehyde. These may be used alone or in combination of two or more.

(E) Drying step The obtained crosslinked film is usually dried after washing. Thereby, a light-polarizing laminated film is obtained. Washing can be performed by immersing the crosslinked film in pure water such as ion exchange water or distilled water. The water washing temperature is usually in the range of 3 to 50 ° C, preferably in the range of 4 to 20 ° C. The immersion time is usually in the range of 2 to 300 seconds, preferably 5 to 240 seconds. The washing may be a combination of a washing treatment with an iodide solution and a water washing treatment, and a solution in which a liquid alcohol such as methanol, ethanol, isopropyl alcohol, butanol, propanol or the like is appropriately blended may be used.

  Any appropriate method (for example, natural drying, air drying, heat drying) can be adopted as the drying method. For example, the drying temperature in the case of heat drying is usually in the range of 20 to 95 ° C., and the drying time is usually about 1 to 15 minutes.

  The polarizing laminated film includes a polarizer layer composed of a polyvinyl alcohol-based resin layer in which a dichroic dye is adsorbed and oriented, and can itself be used as a polarizing plate. As a preferred embodiment of the present invention, after the polarizing laminated film is formed by the above-mentioned process, the polyvinyl alcohol layer of the polarizing laminated film is peeled from the substrate film, whereby the polyvinyl alcohol layer is related to the present invention. It is to be used as a polarizer. According to the method of the present invention, since the thickness of the polarizer layer can be 15 μm or less, a thin polarizer can be obtained. Moreover, the polarizer used in the present invention is excellent in polarization performance and durability.

[Preparation of polarizing plate]
The polarizing plate of the present invention can be produced by a general method. Using a fully saponified polyvinyl alcohol aqueous solution (water glue) on at least one surface of a polarizer prepared by subjecting the polarizer side of the cellulose ester film of the present invention to alkali saponification treatment and immersion drawing in an iodine solution. It is preferable to bond them together. Another polarizing plate protective film can be bonded to the other surface. When the cellulose ester film of the present invention is used as a liquid crystal display device, it is preferably provided on the liquid crystal cell side of the polarizer, and a conventional polarizing plate protective film can be used as the film outside the polarizer.

  For example, as a conventional polarizing plate protective film, a commercially available cellulose ester film (for example, Konica Minoltak KC8UX, KC5UX, KC8UCR3, KC8UCR4, KC8UCR5, KC8UY, KC6UY, KC6UA, KC4UY, KC4UE, KC8UE, KC8UE, KC8UE, KC8UE, KC8UE, RHA, KC8UXW-RHA-C, KC8UXW-RHA-NC, KC4UXW-RHA-NC, manufactured by Konica Minolta, Inc.) are preferably used.

  The direction of bonding with the polarizer is preferably bonded so that, for example, the absorption axis of the polarizer and the slow axis of the cellulose ester film are orthogonal to each other.

[UV curable adhesive]
Moreover, in the polarizing plate of this invention, it is preferable that the cellulose-ester film of this invention and a polarizer are adhere | attached with the ultraviolet curable adhesive.

  In the present invention, by applying an ultraviolet curable adhesive to the bonding of the cellulose ester film and the polarizer, a polarizing plate having high strength and excellent flatness can be obtained even in a thin film. In particular, it is preferable that a polarizing plate protective film of a polyester film type or an acrylic film type is bonded to the other surface because a polarizing plate having high durability against humidity fluctuation can be produced.

<Composition of UV curable adhesive>
As the UV curable adhesive composition for polarizing plates, a photo radical polymerization composition using photo radical polymerization, a photo cation polymerization composition using photo cation polymerization, and photo radical polymerization and photo cation polymerization are used in combination. Hybrid type compositions are known.

  As a radical photopolymerization type composition, a radical polymerizable compound containing a polar group such as a hydroxy group or a carboxy group described in JP-A-2008-009329 and a radical polymerizable compound not containing a polar group are contained in a specific ratio. Composition) and the like are known. In particular, the radical polymerizable compound is preferably a compound having a radical polymerizable ethylenically unsaturated bond. Preferable examples of the compound having an ethylenically unsaturated bond capable of radical polymerization include a compound having a (meth) acryloyl group. Examples of the compound having a (meth) acryloyl group include an N-substituted (meth) acrylamide compound and a (meth) acrylate compound. (Meth) acrylamide means acrylamide or methacrylamide.

  Moreover, as a photocationic polymerization type composition, as disclosed in JP 2011-08234 A, (α) a cationic polymerizable compound, (β) a photocationic polymerization initiator, and (γ) a wavelength longer than 380 nm. And an ultraviolet curable adhesive composition containing each component of a photosensitizer exhibiting maximum absorption in the light of (δ) and a naphthalene-based photosensitization aid. However, other ultraviolet curable adhesives may be used.

(1) Pre-processing process A pre-processing process is a process of performing an easily bonding process to the adhesive surface with the polarizer of a cellulose-ester film. Examples of the easy adhesion treatment include corona treatment and plasma treatment.

(Application process of UV curable adhesive)
In the step of applying the ultraviolet curable adhesive, the ultraviolet curable adhesive is applied to at least one of the adhesive surfaces of the polarizer and the cellulose ester film. When the ultraviolet curable adhesive is applied directly to the surface of the polarizer or the cellulose ester film, the application method is not particularly limited. For example, various wet coating methods such as a doctor blade, a wire bar, a die coater, a comma coater, and a gravure coater can be used. Moreover, after casting an ultraviolet curable adhesive between a polarizer and a cellulose-ester film, the method of pressing with a roller etc. and spreading uniformly can also be utilized.

(2) Bonding process After apply | coating an ultraviolet curable adhesive by said method, it processes by a bonding process. In this bonding step, for example, when an ultraviolet curable adhesive is applied to the surface of the polarizer in the previous application step, a cellulose ester film is superimposed thereon. In the case of a method in which an ultraviolet curable adhesive is first applied to the surface of a cellulose ester film, a polarizer is superimposed thereon. In addition, when an ultraviolet curable adhesive is cast between the polarizer and the cellulose ester film, the polarizer and the cellulose ester film are superposed in that state. Usually, in this state, the pressure is sandwiched between the cellulose ester film sides on both sides with a pressure roller or the like. Metal, rubber, or the like can be used as the material of the pressure roller. The pressure rollers arranged on both sides may be made of the same material or different materials.

(3) Curing step In the curing step, an uncured UV curable adhesive is irradiated with UV rays, and a cationic polymerizable compound (for example, an epoxy compound or an oxetane compound) or a radical polymerizable compound (for example, an acrylate compound, acrylamide). The ultraviolet curable adhesive layer containing the system compound and the like is cured, and the overlapped polarizer and the cellulose ester film are bonded via the ultraviolet curable adhesive. When bonding a cellulose-ester film on the single side | surface of a polarizer, you may irradiate an active energy ray from either a polarizer side or a cellulose-ester film side. In addition, when a cellulose ester film is pasted on both sides of a polarizer, both sides of the polarizer are irradiated with ultraviolet rays with a cellulose ester film superimposed on each other via an ultraviolet curable adhesive. It is advantageous to cure the adhesive simultaneously.

Any appropriate conditions can be adopted as the ultraviolet irradiation conditions as long as the ultraviolet curable adhesive applied to the present invention can be cured. Preferably the dose of ultraviolet rays in the range of 50~1500mJ / cm ² in accumulated light quantity, and even more preferably in the range of 100 to 500 mJ / cm ^2.

  When performing the manufacturing process of a polarizing plate by a continuous line, although line speed is based on the hardening time of an adhesive agent, Preferably it is the range of 1-500 m / min, More preferably, it is the range of 5-300 m / min, More preferably, it is 10- The range is 100 m / min. If the line speed is 1 m / min or more, productivity can be ensured, or damage to the cellulose ester film can be suppressed, and a polarizing plate having excellent durability can be produced. If the line speed is 500 m / min or less, the ultraviolet curable adhesive is sufficiently cured, and an ultraviolet curable adhesive layer having a desired hardness and excellent adhesiveness can be formed.

[Polyester film and acrylic film]
A polyester film or an acrylic film is bonded to the polarizer using water glue or an ultraviolet curable adhesive on the surface of the polarizer opposite to the surface on which the cellulose ester film is bonded. However, this is a preferred embodiment from the viewpoint of obtaining a polarizing plate having high durability against humidity fluctuations. For the pasting, either the water glue or the ultraviolet curable adhesive can be used, but from the viewpoint of the effect of the present invention, it is preferable to use the ultraviolet curable adhesive.

  In the present invention, when the outer film (polarizing plate protective film) is a polyester film or acrylic film having low moisture permeability and the inner film (retardation film) is the cellulose ester film of the present invention, the influence of moisture from the outside. It is presumed that a polarizing plate can be obtained in which the durability of the polarizing plate with respect to humidity fluctuations is comprehensively improved.

(1) Polyester film The polyester resin that forms the polyester film is not particularly limited. For example, terephthalic acid, isophthalic acid, orthophthalic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,4-naphthalene. Dicarboxylic acid, 1,5-naphthalenedicarboxylic acid, diphenylcarboxylic acid, diphenoxyethanedicarboxylic acid, diphenylsulfonecarboxylic acid, anthracene dicarboxylic acid, 1,3-cyclopentanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4 -Cyclohexanedicarboxylic acid, hexahydroterephthalic acid, hexahydroisophthalic acid, malonic acid, dimethylmalonic acid, succinic acid, 3,3-diethylsuccinic acid, glutaric acid, 2,2-dimethylglutaric acid, adipic acid, 2-methyl Dicarboxylic acids such as tiladipic acid, trimethyladipic acid, pimelic acid, azelaic acid, dimer acid, sebacic acid, suberic acid, dodecadicarboxylic acid, ethylene glycol, propylene glycol, hexamethylene glycol, neopentyl glycol, 1,2-cyclohexane Dimethanol, 1,4-cyclohexanedimethanol, decamethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexadiol, 2,2-bis (4 -Hydroxyphenyl) propane, bis (4-hydroxyphenyl) sulfone and other diols, each of which is a homopolymer obtained by polycondensation, or a copolymerization obtained by polycondensation of one or more dicarboxylic acids and two or more diols Combined or two or more dicarboxylic acids Copolymer diol made by polycondensation of one or more of, and can include any of the polyester resin of the blend resin obtained by blending two or more of these homopolymers and copolymers. Of these, polyethylene terephthalate resin is preferably used. Further, the above resins can be mixed and used.

  The polyester film can be obtained, for example, by a method in which the above-described polyester resin is melt-extruded into a film and cooled and solidified with a casting drum to form a film. As the polyester film in the polarizing plate of the present invention, any of an unstretched film and a stretched film can be used. For example, when a film having a small birefringence is required, an unstretched film can be suitably used. In addition, when birefringence is used for optical compensation of a liquid crystal display device, a stretched film can be suitably used. A stretched film, particularly a biaxially stretched film, is also preferably used from the viewpoint of strength.

  Polyester films are more durable than TAC films, but unlike TAC films, they tend to have birefringence, so when used as a polarizing plate protective film, rainbow-like color unevenness occurs when observed from an oblique direction. , The image quality is degraded.

  For this reason, the polyester film is preferably a polyester film having a retardation value in the in-plane direction of 3000 to 30000 nm. At this time, the polarizing plate protective film on the emission light side of the polarizing plate disposed on the emission light side with respect to the liquid crystal cell is preferably a polyester film having a retardation value of 3000 to 30000 nm. The ratio value (Re / Rth) of the retardation value Re in the in-plane direction of the polyester film to the retardation value Rth in the thickness direction is preferably 0.200 or more. With such a configuration, it is possible to obtain a spectrum that approximates the light source at any observation angle, and it is possible to ensure good visibility without rainbow-like color unevenness. Moreover, the mechanical strength suitable for thin film formation can be provided.

  Such a polyester film can use polyethylene terephthalate or polyethylene naphthalate, but may contain other copolymerization components. These resins are excellent in transparency and excellent in thermal and mechanical properties, and the retardation value can be easily controlled by stretching. In particular, polyethylene terephthalate is the most suitable material because it has a large intrinsic birefringence and a relatively large retardation value can be obtained relatively easily even if the film is thin.

  The retardation value can be obtained by measuring the refractive index and thickness in the biaxial direction, and a commercially available automatic birefringence measuring device such as KOBRA-21ADH (Oji Scientific Instruments Co., Ltd.) or Axoscan from Axometrics. It can also be obtained using.

  The polyester film can be manufactured according to a general method for manufacturing a polyester film. For example, the polyester resin is melted and the non-oriented polyester extruded and formed into a sheet shape is stretched in the longitudinal direction by utilizing the speed difference of the roll at a temperature equal to or higher than the glass transition temperature, and then stretched in the transverse direction by a tenter. The method of performing heat processing is mentioned.

  The polyester film used in the present invention may be a uniaxially stretched film or a biaxially stretched film, but when the biaxially stretched film is used as a polarizing plate protective film, it is observed from directly above the film surface. However, rainbow-like color unevenness is not seen, but care must be taken because rainbow-like color unevenness may be observed when observed from an oblique direction.

  This phenomenon is because the biaxially stretched film is composed of refractive index ellipsoids having different refractive indexes in the running direction, width direction, and thickness direction, and the retardation value in the in-plane direction is zero due to the light transmission direction inside the film. This is because there is a direction in which the refractive index ellipsoid looks like a perfect circle. Therefore, when the liquid crystal display screen is observed from a specific oblique direction, a point where the retardation value in the in-plane direction becomes zero may occur, and rainbow-like color unevenness occurs concentrically around that point. It becomes. When the angle from the position directly above the film surface (normal direction) to the position where the rainbow-like color unevenness can be seen is θ, this angle θ becomes larger as the birefringence in the film surface becomes larger. Unevenness is difficult to see. Since the angle θ tends to be small in the biaxially stretched film, the uniaxially stretched film is more preferable because rainbow-like color unevenness is less visible.

  However, a perfect uniaxial (uniaxial symmetry) film is not preferable because the mechanical strength in the direction orthogonal to the orientation direction is significantly reduced. The polyester film used in the present invention is biaxial (biaxial) in a range that does not substantially cause rainbow-like color unevenness or a range that does not cause rainbow-like color unevenness in a viewing angle range required for a liquid crystal display screen. (Symmetry).

  The value of the ratio between the retardation value Re in the in-plane direction of the polarizing plate protective film and the retardation value Rth in the thickness direction of the polarizing plate protective film as a means of suppressing the occurrence of color unevenness while maintaining the mechanical strength of the polarizing plate protective film Is preferably controlled to fall within a specific range. The smaller the difference between the in-plane retardation and the retardation in the thickness direction, the more isotropic the birefringence action due to the observation angle, so the change in retardation due to the observation angle becomes smaller. For this reason, it is considered that rainbow-like color unevenness due to the observation angle hardly occurs.

  The ratio value (Re / Rth) of the retardation value Re in the in-plane direction and the retardation value Rth in the thickness direction of the polyester film used in the present invention is preferably 0.200 or more, more preferably 0.500 or more. More preferably, it is 0.600 or more. As the ratio of the retardation value Re in the in-plane direction to the retardation value Rth in the thickness direction (Re / Rth) is larger, the birefringence action is more isotropic, and rainbow-like color unevenness occurs depending on the observation angle. Is less likely to occur. In a perfect uniaxial (uniaxial symmetry) film, the ratio value (Re / Rth) of the retardation value Re in the in-plane direction and the retardation value Rth in the thickness direction is 2.0. However, as described above, the mechanical strength in the direction orthogonal to the orientation direction is significantly lowered as the film approaches a complete uniaxial (uniaxial symmetry) film.

  On the other hand, the ratio value (Re / Rth) of the retardation value Re in the in-plane direction and the retardation value Rth in the thickness direction of the polyester film used in the present invention is preferably 1.2 or less, more preferably 1. 0 or less. In order to completely suppress the occurrence of rainbow-like color unevenness due to the observation angle, the ratio value (Re / Rth) of the in-plane retardation value Re and the thickness direction retardation value Rth is 2.0. There is no need, and 1.2 or less is sufficient. Even if the ratio is 1.0 or less, it is possible to satisfy the viewing angle characteristics (180 degrees left and right, 120 degrees up and down) required for the liquid crystal display device.

  Describing specifically the film forming conditions of the polyester film used in the present invention, the longitudinal stretching temperature and the transverse stretching temperature are preferably from 80 to 130 ° C, particularly preferably from 90 to 120 ° C. The longitudinal draw ratio is preferably from 1.0 to 3.5 times, particularly preferably from 1.0 to 3.0 times. Further, the transverse draw ratio is preferably 2.5 to 6.0 times, particularly preferably in the range of 3.0 to 5.5 times. In order to control the retardation value within the above range, it is preferable to control the ratio of the longitudinal draw ratio and the transverse draw ratio. If the difference between the vertical and horizontal stretch ratios is too small, it is difficult to increase the retardation value. Also, setting the stretching temperature low is a preferable measure for increasing the retardation value. In the subsequent heat treatment, the treatment temperature is preferably from 100 to 250 ° C, particularly preferably from 180 to 245 ° C.

  In order to suppress the fluctuation of the retardation value, it is preferable that the thickness unevenness of the film is small. Since the stretching temperature and the stretching ratio greatly affect the thickness unevenness of the film, it is necessary to optimize the film forming conditions from the viewpoint of the thickness unevenness. In particular, when the longitudinal stretching ratio is lowered in order to increase the retardation value, the thickness unevenness in the longitudinal direction may be deteriorated. Since there is a region where the thickness unevenness in the vertical direction becomes extremely worse in a specific range of the draw ratio, it is desirable to set the film forming conditions outside this range.

  The thickness unevenness of the film is preferably 5.0% or less, more preferably 4.5% or less, still more preferably 4.0% or less, and 3.0% or less. Is particularly preferred.

  As described above, in order to control the retardation value of the film within a specific range, the stretching ratio, the stretching temperature, and the thickness of the film can be appropriately set. For example, the higher the stretching ratio, the lower the stretching temperature, and the thicker the film, the easier it is to obtain a higher retardation value. Conversely, the lower the stretching ratio, the higher the stretching temperature, and the thinner the film, the easier it is to obtain a lower retardation value. However, when the thickness of the film is increased, the retardation value in the thickness direction tends to increase. Therefore, it is desirable to set the film thickness appropriately in the range described later. In addition to controlling the retardation value, it is necessary to set final film forming conditions in consideration of physical properties necessary for processing.

  Although the thickness of the polyester film used for this invention is arbitrary, the range of 15-300 micrometers is preferable, More preferably, it is the range of 15-200 micrometers. Even in the case of a film having a thickness of less than 15 μm, it is possible in principle to obtain a retardation value of 3000 nm or more. However, in that case, the anisotropy of the mechanical properties of the film becomes remarkable, and it becomes easy to cause tearing, tearing, etc., and the practicality as an industrial material is remarkably lowered. A particularly preferable lower limit of the thickness is 25 μm. On the other hand, if the upper limit of the thickness of the polyester film exceeds 300 μm, the thickness of the polarizing plate becomes too thick, which is not preferable. From the viewpoint of practicality as a polyester film, the upper limit of the thickness is preferably 200 μm. A particularly preferable upper limit of the thickness is 100 μm, which is about the same as a general TAC film. In order to control the retardation value within the range of the present invention even in the thickness range, polyethylene terephthalate is preferable as the polyester used as the film substrate.

  Various additives may be used in the polyester film used in the present invention. Examples of other additives include plasticizers, ultraviolet absorbers, fluorine-based surfactants, release agents, matting agents, deterioration preventing agents, optical anisotropy control agents, infrared absorbers, and the like. Can be used.

(2) Acrylic film The acrylic resin contained in an acrylic film means a (meth) acrylic resin and is a concept including both an acrylic resin and a methacrylic resin. Hereinafter, the acrylic resin will be described.

  As described above, the acrylic resin is a (meth) acrylic resin and means a polymer of acrylic acid ester or methacrylic acid ester. As the polymer of the methacrylic acid ester, for example, a polymer composed mainly of an alkyl methacrylate is preferable. The monomer composition of the alkyl methacrylate is preferably 70% by mass or more, more preferably 80% by mass or more, and still more preferably 90% by mass or more, based on a total of 100% by mass of all monomers. And alkyl methacrylate is 99% by mass or less. The acrylic resin may be a homopolymer of alkyl methacrylate or a copolymer of 50% by mass or more of alkyl methacrylate and 50% by mass or less of a monomer other than alkyl methacrylate. Good. As the alkyl methacrylate, those having 1 to 4 carbon atoms of the alkyl group are usually used, and among them, methyl methacrylate is preferably used.

  The monomer other than alkyl methacrylate may be a monofunctional monomer having one polymerizable carbon-carbon double bond in the molecule, or two or more polymerizable carbons in the molecule. -A polyfunctional monomer having a carbon double bond may be used. In particular, monofunctional monomers are preferably used, and examples thereof include alkyl acrylates such as methyl acrylate and ethyl acrylate, and further, such as styrene and alkyl styrene as long as the effects of the present invention are not impaired. Examples include styrene monomers and unsaturated nitriles such as acrylonitrile and methacrylonitrile. When using alkyl acrylate as a copolymerization component, the carbon number is 1-8 normally.

  The acrylic resin preferably does not have a glutarimide derivative, a glutaric anhydride derivative, a lactone ring structure, or the like. These acrylic resins may not have sufficient mechanical strength and heat-and-moisture resistance as an acrylic film.

  In the present invention, the weight average molecular weight (Mw) of the acrylic resin used in the present invention can be reduced from the viewpoint that the content of the organic solvent in the dope can be reduced, the drying time can be shortened, and the surface shape of the film to be formed is excellent. ) Is preferably 80,000 or more. Further, from the viewpoint of further improving the film surface shape when laminated, the weight average molecular weight of the acrylic resin is in the range of 100,000 to 4000000. preferable.

  The upper limit of the weight average molecular weight of the acrylic resin can maintain the solution casting suitability without excessively increasing the viscosity, and can ensure compatibility with organic solvents and additives during dope preparation. The upper limit is preferably 4000000.

  The weight average molecular weight of the acrylic resin used in the present invention can be measured by the gel permeation chromatography.

  In order to improve the flexibility of the acrylic film and enhance the handling properties, it is preferable that rubber elastic particles are blended in the acrylic resin. The rubber elastic particles are particles containing a rubber elastic body, and may be particles composed only of a rubber elastic body, or may be particles having a multilayer structure having a rubber elastic body layer. Examples of rubber elastic bodies include olefin-based elastic polymers, diene-based elastic polymers, styrene-diene-based elastic copolymers, and acrylic-based elastic polymers. Among these, an acrylic elastic polymer is preferable from the viewpoint of the surface hardness, light resistance, and transparency of the acrylic film.

  The acrylic elastic polymer is preferably a polymer mainly composed of alkyl acrylate, may be a homopolymer of alkyl acrylate, or may be a single polymer other than alkyl acrylate 50 mass% or more and alkyl acrylate. It may be a copolymer with 50% by mass or less of the monomer. As the alkyl acrylate, those having 4 to 8 carbon atoms in the alkyl group are usually used. Examples of monomers other than alkyl acrylate include alkyl methacrylates such as methyl methacrylate and ethyl methacrylate, styrene monomers such as styrene and alkyl styrene, acrylonitrile and methacrylonitrile. Monofunctional monomers such as unsaturated nitriles, alkenyl esters of unsaturated carboxylic acids such as allyl (meth) acrylate and methallyl (meth) acrylate, dialkenyl esters of dibasic acids such as diallyl maleate, And polyfunctional monomers such as unsaturated carboxylic acid diesters of glycols such as alkylene glycol di (meth) acrylate.

  The rubber elastic particle containing the acrylic elastic polymer is preferably a particle having a multilayer structure having an acrylic elastic polymer layer, and a polymer mainly composed of alkyl methacrylate outside the acrylic elastic polymer. It may be a two-layer structure having the above-mentioned layer, or a three-layer structure having a polymer layer mainly composed of alkyl methacrylate inside the acrylic elastic polymer. In addition, the example of the monomer composition of the polymer mainly composed of alkyl methacrylate constituting the layer formed on the outside or inside of the acrylic elastic polymer is the same as the alkyl methacrylate previously mentioned as an example of the acrylic resin. This is the same as the monomer composition example of the main polymer. Such acrylic rubber elastic particles having a multilayer structure can be produced, for example, by the method described in Japanese Patent Publication No. 55-27576.

  As the rubber elastic particles, those having a number average particle diameter of 10 to 300 nm of the rubber elastic bodies contained therein can be used. Thereby, when an acrylic film is laminated | stacked on a polarizing film using an adhesive agent, an acrylic film can be made hard to peel from an adhesive bond layer. The number average particle diameter of the rubber elastic body is preferably 50 nm or more and 250 nm or less.

  In the rubber elastic particle in which the outermost layer is a polymer mainly composed of methyl methacrylate and the acrylic elastic polymer is encapsulated in the polymer, when the rubber elastic particle is mixed with the base acrylic resin, the rubber elastic particle The outermost layer is mixed with the base acrylic resin. Therefore, in the cross section, when the acrylic elastic polymer is dyed with ruthenium oxide and observed with an electron microscope, the rubber elastic particles can be observed as particles excluding the outermost layer. Specifically, in the case of using rubber elastic particles having a two-layer structure in which the inner layer is an acrylic elastic polymer and the outer layer is a polymer mainly composed of methyl methacrylate, the inner layer is an acrylic elastic polymer. The portion is dyed and observed as particles having a single layer structure. Further, the rubber elastic particles having a three-layer structure in which the innermost layer is a polymer mainly composed of methyl methacrylate, the intermediate layer is an acrylic elastic polymer, and the outermost layer is a polymer mainly composed of methyl methacrylate. When is used, the center part of the innermost layer particle is not dyed, and only the acrylic elastic polymer part of the intermediate layer is dyed and observed as a two-layered particle.

  In the present specification, the number average particle diameter of the rubber elastic particles is, as described above, when the rubber elastic particles are mixed with the base resin and the cross section is dyed with ruthenium oxide, and is dyed in a substantially circular shape. It is the number average value of the diameters of the parts observed in FIG.

  In the acrylic film, the blending amount of the rubber elastic particles is not particularly limited. For example, 25 to 45% by mass of rubber elastic particles having a number average particle diameter of 10 to 300 nm are blended in a transparent acrylic resin. Those are preferred.

  The acrylic resin may be produced, for example, by obtaining rubber elastic particles and then polymerizing a monomer as a raw material of the acrylic resin in the presence thereof to produce a base acrylic resin, or rubber. After obtaining the elastic particles and the acrylic resin, they may be produced by mixing them by melt kneading or the like.

  The glass transition temperature Tg of the acrylic resin is preferably in the range of 80 to 120 ° C. Further, the acrylic resin preferably has a high surface hardness when formed into a film, specifically, a pencil hardness (load of 500 g, conforming to JIS K5600-5-4) of B or more.

  The acrylic film preferably has a flexural modulus (JIS K7171) of 1500 MPa or less from the viewpoint of the flexibility of the acrylic resin. The flexural modulus is more preferably 1300 MPa or less, and still more preferably 1200 MPa or less. This flexural modulus varies depending on the type and amount of acrylic resin and rubber elastic particles in the acrylic film. For example, as the content of rubber elastic particles increases, the flexural modulus generally decreases. In addition, the flexural modulus is generally smaller when an acrylic resin is a copolymer of alkyl methacrylate and alkyl acrylate than a homopolymer of alkyl methacrylate.

  In addition, the elastic elastic polymer particles having the two-layer structure are generally used as the elastic rubber particles, rather than the acrylic elastic polymer particles having the two-layer structure. In general, the flexural modulus is smaller when the acrylic elastic polymer particles having a layer structure are used. Further, in the rubber elastic body particles, as the average particle diameter of the rubber elastic body is smaller or the amount of the rubber elastic body is larger, the bending elastic modulus is generally smaller. Therefore, it is preferable to adjust the kind and amount of acrylic resin and rubber elastic body particles within the predetermined range so that the flexural modulus is 1500 MPa or less.

  When the acrylic film has a multilayer structure, the layer that can exist other than the layer of the acrylic resin composition is not particularly limited in composition, for example, an acrylic resin that does not contain rubber elastic particles or a layer of the composition. Alternatively, it may be a layer made of an acrylic resin in which the content of the rubber elastic body particles and the average particle diameter of the rubber elastic body in the rubber elastic body particles are not specified above.

  Typically, it has a two-layer or three-layer structure, for example, a two-layer structure including an acrylic resin layer / an acrylic resin not containing rubber elastic particles or a layer of the composition thereof, or an acrylic resin. A three-layer structure comprising an acrylic resin not containing rubber elastic particles or a composition layer / acrylic resin composition layer may be employed. What is necessary is just to let the surface of the layer of an acrylic resin composition be a bonding surface with a polarizer in the multilayer acrylic film.

  Moreover, when making an acrylic film into a multilayer structure, you may mutually differ content of rubber elastic-body particle | grains or each layer of the said compounding agent. For example, a layer containing an ultraviolet absorber and / or an infrared absorber and a layer not containing an ultraviolet absorber and / or an infrared absorber may be laminated with this layer interposed therebetween. Further, the content of the ultraviolet absorber in the acrylic resin composition layer may be higher than the content of the ultraviolet absorber in the acrylic resin or the composition layer containing no rubber elastic particles, Specifically, the former is preferably 0.5 to 10% by mass, more preferably 1 to 5% by mass, and the latter is preferably 0 to 1% by mass, more preferably 0 to 0.5% by mass. Thus, ultraviolet rays can be efficiently blocked without deteriorating the color tone of the polarizing plate, and a decrease in the degree of polarization during long-term use can be prevented.

  The acrylic film may be non-oriented or unstretched, or may be stretched. When the stretching treatment is not performed, the total film thickness of the polarizing plate is likely to be increased because the film thickness is increased, but on the other hand, the handling property of the acrylic film is improved due to the thick film thickness. Such an acrylic film can be obtained from an unstretched film (raw film) obtained by forming an acrylic resin composition. On the other hand, when stretched, the phase difference is easily developed. On the other hand, stretching has the advantage that the thickness of the acrylic film is reduced and the rigidity is improved. The stretched film can be produced by stretching an unstretched film by an arbitrary method.

  The acrylic resin can be formed into an unstretched film by any method. This unstretched film is preferably transparent and substantially free of in-plane retardation. Examples of the film forming method include an extrusion method for forming a film by extruding a molten resin into a film, and a solvent casting method for forming a film by removing a solvent after casting a resin dissolved in an organic solvent on a flat plate. Etc. can be adopted.

  As a specific example of the extrusion molding method, for example, there is a method of forming a film in a state where the acrylic resin composition is sandwiched between two rolls. At this time, by varying the rigidity of the roll surface, it is possible to make one surface of the acrylic film smooth and the other surface rough.

  As a specific example of the extrusion molding method, for example, there is a method of forming a film in a state where the acrylic resin composition is sandwiched between two metal rolls. In this case, the metal roll is preferably a mirror roll. Thereby, the unstretched film excellent in surface smoothness can be obtained. In addition, when obtaining the thing of multilayer structure as an acrylic film, what is necessary is just to film-form the said acrylic resin composition after multilayer extrusion with another acrylic resin composition. The thickness of the unstretched film thus obtained is preferably in the range of 5 to 200 μm, more preferably in the range of 10 μm to 85 μm.

≪Liquid crystal display device≫
By using the polarizing plate on which the cellulose ester film of the present invention is bonded to a liquid crystal display device, the liquid crystal display device of the present invention having excellent visibility can be produced.

  The polarizing plate of the present invention can be used for liquid crystal display devices of various drive systems such as STN, TN, OCB, HAN, VA (MVA, PVA), IPS, OCB and the like. A VA (MVA, PVA) type liquid crystal display device is preferable.

  In the liquid crystal display device, usually two polarizing plates, a polarizing plate on the viewing side and a polarizing plate on the backlight side, are used, but it is also preferable to use the polarizing plate of the present invention as both polarizing plates. It is also preferable to use as. In particular, the polarizing plate of the present invention is preferably used as a viewing-side polarizing plate that directly touches the external environment. In that case, the cellulose ester film of the present invention is preferably disposed on the liquid crystal cell side as a retardation film.

  The direction of bonding of the polarizing plate in the VA mode liquid crystal display device can be performed with reference to JP-A-2005-234431.

  Further, the polarizing plate on the backlight side may be a polarizing plate other than the present invention. In that case, both sides of the polarizer may be, for example, a commercially available cellulose ester film (for example, Konica Minoltack KC8UX, KC5UX, KC4UX, KC8UCR3, KC4SR, KC4BR, KC4CR, KC4DR, KC4FR, KC4KR, KC8UY, KC6UY, KC4UY, KC4UE, KC8UE, KC8UY-HA, KC2UA, KC4UA, KC6UA, KC4UAH, KC2UAH, KC4UAH, KC4UAH, KC4UAH, KC4UAH T60UZ, Fujitac T80UZ, Fujitac TD80UL, Fujitac TD60UL, Fujitac TD40UL, Fujitac T25TG, Fujitac T40TG, Fujitac T2 TJ, FUJITAC T40TJ, FUJITAC R02, FUJITAC R06, FUJITAC R032, FUJITAC r033, or produced by Fujifilm Corp., etc.) bonded combined polarizing plate is preferably used.

  Further, as the polarizing plate on the backlight side, the cellulose ester film of the present invention is used on the liquid crystal cell side of the polarizer, and the above-mentioned commercially available cellulose ester film, polyester film, acrylic film, polycarbonate film, or cycloolefin is used on the opposite surface. A polarizing plate bonded with a polymer film can also be preferably used.

  By using the polarizing plate of the present invention, it is possible to obtain a liquid crystal display device excellent in visibility such as display unevenness and front contrast, even in the case of a large-screen liquid crystal display device having a screen size of 30 or more.

  Moreover, the polarizing plate of this invention can be preferably used for an organic electroluminescent display apparatus besides a liquid crystal display apparatus. For example, the circularly polarizing plate is obtained by stretching the cellulose ester film of the present invention in a 45 ° oblique direction with respect to the transport direction, and laminating the polarizer having an absorption axis in the transport direction with a roll-to-roll. When manufactured and the circularly polarizing plate is used for an organic electroluminescence display device, a display device with high visibility can be obtained.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In addition, although the display of "part" or "%" is used in an Example, unless otherwise indicated, "part by mass" or "mass%" is represented.

Example 1
Table 1 shows the contents of the cellulose ester used in the examples. In the table, DAC: diacetyl cellulose, CAP: cellulose acetate propionate, and TAC: triacetyl cellulose, respectively.

<Production of cellulose ester film>
[Production of Cellulose Ester Film 101]
The cellulose ester film 101 was produced according to the following method.

(Preparation of fine particle dispersion)
10 parts by weight Aerosil R812 (manufactured by Nippon Aerosil Co., Ltd., primary average particle size: 7 nm, apparent specific gravity 50 g / L) and 90 parts by weight of ethanol were stirred and mixed with a dissolver for 30 minutes, and then high pressure disperser Manton Gorin Was used to prepare a fine particle dispersion.

  88 parts by mass of dichloromethane was added to the obtained fine particle dispersion while stirring, and the mixture was stirred and mixed with a dissolver for 30 minutes to dilute. The obtained solution was filtered with a polypropylene wind cartridge filter TCW-PPS-1N manufactured by Advantech Toyo Co., Ltd. to obtain a fine particle dispersion dilution.

(Preparation of inline additive solution)
To 100 parts by mass of dichloromethane, 36 parts by mass of the prepared fine particle dispersion diluted solution was added with stirring, and further stirred for 30 minutes, and then 6 parts by mass of DAC1 (acetyl group substitution degree 2.32, weight average molecular weight 270,000). ) Was added with stirring and further stirred for 60 minutes. The obtained solution was filtered with Finemet NF manufactured by Nippon Seisen Co., Ltd. to obtain an in-line additive solution. The filter medium having a nominal filtration accuracy of 20 μm was used.

(Preparation of dope)
The following components were put into a sealed container and completely dissolved with heating and stirring. The obtained solution was filtered with a filter equipped with a leaf disk filter at a temperature of 50 ° C. (boiling point of dichloromethane + 10 ° C.) to obtain a main dope. The filter medium having a nominal filtration accuracy of 20 μm was used.

<Composition of main dope>
Diacetylserose DAC1 (acetyl group substitution degree: 2.32, weight average molecular weight 270,000) 100 parts by mass Retardation increasing agent (compound having a structure represented by general formula (1): exemplary compound 1-1) 4 masses Part sugar ester; BzSc (benzyl sucrose: mixture of compounds a1 to a4 described in Chemical formula 7), average ester substitution degree = 5.5 7 parts by mass polycondensed ester: polycondensed ester represented by formula (2): P8
5 parts by mass Dichloromethane 430 parts by mass Methanol 11 parts by mass 100 parts by mass of the main dope 1 and 2.5 parts by mass of the in-line additive solution are sufficiently obtained with an in-line mixer (Toray static in-tube mixer Hi-Mixer, SWJ). The dope was obtained by mixing.

(Film forming process)
The obtained dope was uniformly cast on a stainless steel band support using a belt casting apparatus under the conditions of a dope liquid temperature of 35 ° C. and a width of 1.95 m and a final film thickness of 33 μm. . On the stainless steel band support, the organic solvent in the obtained dope film was evaporated until the residual solvent amount reached 100% by mass to form a web, and then the web was peeled from the stainless steel band support. The obtained web was further pre-dried at 60 ° C. for 5 minutes to make the residual solvent amount 5% by mass, and then the web was 1.25 times the original width in the TD direction at 160 ° C. with a tenter. Stretched. The stretching speed was 300% / min.

  After stretching with a tenter, relaxation was performed at 130 ° C. for 5 minutes, and then drying was completed while the drying zone was being conveyed by a number of rollers. The drying temperature was 130 ° C. and the transport tension was 100 N / m. The obtained film was slit to 2.0 m width, 10 mm wide and 5 μm knurled at both ends of the film, wound on a core of 15.24 cm in inner diameter with an initial tension of 220 N / m and a final tension of 110 N / m. A cellulose ester film 101 having a thickness of 4000 m and a dry film thickness of 33 μm was obtained.

[Production of Cellulose Ester Films 102 to 129]
In the production of the cellulose ester film 101, the types of diacetyl cellulose (DAC2 to DAC4), the types and addition amounts of the retardation increasing agent, the filtration temperature, the residual solvent amount, and the stretching speed are changed as shown in Table 2 and Table 3. Cellulose ester films 101 to 129 were produced in the same manner except for the above.

  The structures of compounds 1 to 5 which are comparative retardation increasing agents are shown below.

  The following evaluation was performed using the produced cellulose ester films 101-129.

≪Evaluation≫
<Contact angle and standard deviation>
The contact angle of pure water on the film surface was measured by leaving the cellulose ester film sample for 24 hours in an atmosphere at a temperature of 23 ° C. and a relative humidity of 55%. Using a Kyowa Interface Science Co., Ltd. product name DropMaster DM100), the contact angle of pure water 1 minute after dropping 1 μl of pure water is measured. In addition, the measurement measured 20 points | pieces at equal intervals with respect to the film width direction, remove | excluded the maximum value and the minimum value, made the average value the contact angle, and calculated | required the said standard deviation of 20 points | pieces simultaneously.

  The standard deviation σ when N = 20 is obtained from the following equation.

（Ｎは試料数を表す。ｘ_iはそれぞれの測定値を表す。ｍはＮ個の試料数の平均値を表す。）
＜波長３２０ｎｍ測定での光透過率＞
３２０ｎｍの波長での光透過率は、温度２３℃、相対湿度５５％の雰囲気下でセルロースエステルフィルム試料の任意の１０点について、分光光度計（日立ハイテクフィールディング製Ｕ−３３００）を用いて、測定波長３２０ｎｍにおける光透過率（％）を測定し平均値を求めた。

(N represents the number of samples. X _i represents each measured value. M represents the average value of N samples.)
<Light transmittance at wavelength of 320 nm measurement>
The light transmittance at a wavelength of 320 nm was measured using a spectrophotometer (U-3300 manufactured by Hitachi High-Tech Fielding Co., Ltd.) for any 10 points of the cellulose ester film sample in an atmosphere having a temperature of 23 ° C. and a relative humidity of 55%. The light transmittance (%) at a wavelength of 320 nm was measured to obtain an average value.

<Retardation measurement>
In-plane retardation value Re and thickness direction retardation value Rth were measured using an automatic birefringence meter Axoscan (Axo Scan Mueller Matrix Polarimeter: manufactured by Axometrics) under an environment of 23 ° C. and 55% RH. It can be calculated by the following formulas (i) and (ii) from the obtained refractive indexes nx, ny, and nz at a light wavelength of 590 nm by performing a three-dimensional refractive index measurement.

Formula _{(i): Re = (n} x -n y) × d (nm)
Formula (ii): Rth = {(n _x + n _y ) / 2−n _z } × d (nm)
In [Equation (i) and Formula (ii), n _x represents a refractive index in the direction x in which the refractive index is maximized in the plane direction of the film. n _y, in-plane direction of the film, the refractive index in the direction y perpendicular to the direction x. _nz represents the refractive index in the thickness direction z of the film. d represents the thickness (nm) of the film. ]
<Evaluation of adhesion with water glue>
[Production of Polarizing Plates A101 to A129]
The surface of each cellulose ester film produced above was subjected to alkali saponification treatment. It was immersed in a 1.5 N aqueous sodium hydroxide solution at 55 ° C. for 2 minutes, washed in a water bath at room temperature, and neutralized with 0.1 N sulfuric acid at 30 ° C. Again, it was washed in a water bath at room temperature and further dried with hot air at 100 ° C.

  Subsequently, a roll-shaped polyvinyl alcohol film having a thickness of 80 μm was continuously stretched 5 times in an aqueous iodine solution and dried to obtain a polarizer 1 having a thickness of 20 μm. Using a 3% aqueous solution of polyvinyl alcohol (Kuraray PVA-117H) as an adhesive, the above-mentioned alkali saponified cellulose ester films and the same alkali saponified Konica Minolta Tack KC6UA (manufactured by Konica Minolta Co., Ltd.) The polarizing plates A101 to A129 are prepared and bonded so that the saponified surfaces are on the polarizer side with the polarizer interposed therebetween, and the cellulose ester films, the polarizer 1, and KC6UA are bonded in this order. Respectively. Under the present circumstances, it affixed so that the MD direction of each cellulose-ester film and the slow axis of KC6UA might be orthogonal to the absorption axis of a polarizer.

[Evaluation of adhesion]
The adhesion of polarizing plates A101 to A129 was evaluated according to the following criteria.

  The operation of peeling off the optical film of the produced polarizing plate from the polarizer was performed 10 times, and the adhesion interface with the optical film / polarizer was visually observed. Thereby, the adhesiveness of the optical film / polarizer was evaluated according to the following criteria.

◎: Not peeled completely even 10 times ○: Not completely peeled, but may peel partially △: Completely peeled 1 to 3 times out of 10 times ×: Completely peeled out 4 times or more out of 10 times <Evaluation of visibility of liquid crystal display device>
[Production of Liquid Crystal Display Devices A101 to 129]
An acrylic pressure-sensitive adhesive containing butyl acrylate on both sides of the glass surface of the liquid crystal cell by removing the polarizing plates on both sides of the 40-inch display BRAVIA X1 made in advance from Sony. It was pasted using.

  At that time, the direction of bonding of the polarizing plate is such that the surface of the cellulose ester film of the example is on the liquid crystal cell side, and the absorption axis is in the same direction as the polarizing plate previously bonded. Thus, liquid crystal display devices A101 to A129 respectively corresponding to the polarizing plates A101 to A129 were produced.

[Visibility: Evaluation of contrast]
When a white image was displayed on the liquid crystal display device, the Y value of the XYZ display system in the azimuth angle 45 ° direction and polar angle 60 ° direction of the display screen was measured by a product name “EZ Contrast 160D” manufactured by ELDIM. Similarly, the Y value of the XYZ display system in the azimuth angle 45 ° direction and polar angle 60 ° direction of the display screen when displaying a black image on the liquid crystal display device was measured. Then, the contrast ratio “YW / YB” in the oblique direction was calculated from the Y value (YW) in the white image and the Y value (YB) in the black image. The contrast ratio was measured in a dark room at a temperature of 23 ° C. and a relative humidity of 55%. The azimuth angle of 45 ° represents an azimuth rotated 45 ° counterclockwise when the long side of the display screen is 0 ° in the plane of the display screen. The polar angle of 60 ° represents a direction inclined by 60 ° with respect to the normal line when the normal direction of the display screen is 0 °. The higher the contrast ratio, the higher the contrast and the better.

◎: Contrast ratio is 60 or more ○: Contrast ratio is 55 or more and less than 60 Δ: Contrast ratio is 50 or more and less than 55 ×: Contrast ratio is less than 50 <UV (UV ) Adhesive evaluation with curable adhesive>
[Production of polyester film]
First, a polyester film was prepared according to the following procedure.

(Production Example 1-Polyester A)
When the temperature of the esterification reactor was raised to 200 ° C., 86.4 parts by mass of terephthalic acid and 64.6 parts by mass of ethylene glycol were charged and 0.017 parts by mass of antimony trioxide as a catalyst while stirring. 0.064 parts by mass of magnesium acetate tetrahydrate and 0.16 parts by mass of triethylamine were charged. Next, the pressure was raised and the pressure esterification reaction was carried out under conditions of a gauge pressure of 0.34 MPa and 240 ° C., and then the esterification reaction vessel was returned to normal pressure, and 0.014 parts by mass of phosphoric acid was added. Furthermore, it heated up to 260 degreeC over 15 minutes, and 0.012 mass part of trimethyl phosphate was added. Then, after 15 minutes, dispersion treatment was performed with a high-pressure disperser, and after 15 minutes, the obtained esterification reaction product was transferred to a polycondensation reaction can and subjected to polycondensation reaction at 280 ° C. under reduced pressure.

After completion of the polycondensation reaction, it is filtered through a NASRON filter with a 95% cut diameter of 5 μm, extruded in a strand form from a nozzle, and cooled and solidified using cooling water that has been filtered in advance (pore diameter: 1 μm or less). And cut into pellets. The obtained polyethylene terephthalate resin (A) had an intrinsic viscosity of 0.62 dl / g and contained substantially no inert particles and internally precipitated particles. (Hereafter, abbreviated as PET (A).)
(Production Example 2-Polyester B)
Next, 10 parts by weight of a dried UV absorber (2,2 ′-(1,4-phenylene) bis (4H-3,1-benzoxazinon-4-one), PET (A) containing no particles 90 parts by mass (inherent viscosity is 0.62 dl / g) was mixed, and a polyethylene terephthalate resin (B) containing an ultraviolet absorber was obtained using a kneading extruder (hereinafter abbreviated as PET (B)).

(Production Example 3-Preparation of Adhesive Modified Coating Solution)
A transesterification reaction and a polycondensation reaction are performed by a conventional method, and as a dicarboxylic acid component (based on the whole dicarboxylic acid component) 46 mol% terephthalic acid, 46 mol% isophthalic acid, and 8 mol% sodium 5-sulfonatoisophthalate, A water-dispersible sulfonic acid metal group-containing copolymer polyester resin having a composition of 50 mol% ethylene glycol and 50 mol% neopentyl glycol (relative to the entire glycol component) was prepared as a glycol component. Next, 51.4 parts by mass of water, 38 parts by mass of isopropyl alcohol, 5 parts by mass of n-butyl cellosolve, 0.06 parts by mass of nonionic surfactant were mixed and then heated and stirred. After adding 5 parts by mass of a water-dispersible sulfonic acid metal base-containing copolymer polyester resin and continuing to stir until the resin is no longer agglomerated, the resin water dispersion is cooled to room temperature to obtain a solid content concentration of 5.0% by mass. A uniform water-dispersible copolymerized polyester resin liquid was obtained. Furthermore, after dispersing 3 parts by mass of aggregated silica particles (manufactured by Fuji Silysia Co., Ltd., Silicia 310) in 50 parts by mass of water, 99.46 parts by mass of the water-dispersible copolymerized polyester resin liquid was mixed with water of Silicia 310. 0.54 parts by mass of the dispersion was added, and 20 parts by mass of water was added with stirring to obtain an adhesive modified coating solution.

(Preparation of PET film)
After drying 90 parts by mass of PET (A) resin pellets containing no particles as a raw material for the base film intermediate layer and 10 parts by mass of PET (B) resin pellets containing an ultraviolet absorber at 135 ° C. for 6 hours under reduced pressure (1 Torr) , And supplied to the extruder 2 (for the intermediate layer II layer), and PET (A) was dried by a conventional method and supplied to the extruder 1 (for the outer layer I layer and the outer layer III), respectively, and dissolved at 285 ° C. . After filtering these two kinds of polymers with a filter medium made of a sintered stainless steel (nominal filtration accuracy of 10 μm particles 95% cut), laminating them in a two-kind / three-layer confluence block, and extruding them into a sheet form from a die, The film was wound around a casting drum having a surface temperature of 30 ° C. using an electrostatic application casting method, and then cooled and solidified to produce an unstretched film. At this time, the discharge amount of each extruder was adjusted so that the ratio of the thicknesses of the I layer, the II layer, and the III layer was 10:80:10.

Next, after applying the above-mentioned adhesiveness-modified coating solution on the both sides of this unstretched PET film by a reverse roll method so that the coating amount after drying becomes 0.096 g / m ² , the coating was dried at 80 ° C. for 20 seconds. .

  The unstretched film on which this coating layer was formed was guided to a tenter stretching machine, and the film was guided to a hot air zone at a temperature of 125 ° C. while being gripped by a clip, and stretched 4.0 times in the width direction. Next, while maintaining the width stretched in the width direction, the film was treated at a temperature of 225 ° C. for 30 seconds and further subjected to a relaxation treatment of 3% in the width direction to obtain a uniaxially oriented polyester film having a film thickness of 60 μm.

[Preparation of UV curable adhesive solution 1]
After mixing the following components, defoaming was performed to prepare an ultraviolet curable adhesive liquid 1. Triarylsulfonium hexafluorophosphate was blended as a 50% propylene carbonate solution, and the solid content of triarylsulfonium hexafluorophosphate was shown below.

3,4-Epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate 45 parts by mass Epolide GT-301 (Daicel's alicyclic epoxy resin)
40 parts by mass 1,4-butanediol diglycidyl ether 15 parts by mass Triarylsulfonium hexafluorophosphate 2.3 parts by mass 9,10-dibutoxyanthracene 0.1 parts by mass 1,4-diethoxynaphthalene 2.0 parts by mass [Production of Polarizing Plates B101 to B129]
Polarizing plates B101 to B129 were prepared according to the following method.

  First, the surface of the cellulose ester film of the above example was subjected to corona discharge treatment. The corona discharge treatment was performed at a corona output intensity of 2.0 kW and a line speed of 18 m / min. Next, the ultraviolet curable adhesive liquid 1 prepared above is applied to the corona discharge treated surface of the cellulose ester film with a bar coater so that the film thickness after curing is about 3 μm, and the ultraviolet curable adhesive layer is formed. Formed. The produced polarizer 1 was bonded to the obtained ultraviolet curable adhesive layer.

  Next, the produced polyester film was subjected to corona discharge treatment. The conditions of the corona discharge treatment were a corona output intensity of 2.0 kW and a speed of 18 m / min.

  Next, the ultraviolet curable adhesive liquid 1 prepared above is applied to the corona discharge treated surface of the polyester film with a bar coater so that the film thickness after curing is about 3 μm to form an ultraviolet curable adhesive layer. did.

  A polarizer having the cellulose ester film bonded on one side is bonded to the ultraviolet curable adhesive layer, and cellulose ester film / ultraviolet curable adhesive layer / polarizer / ultraviolet curable adhesive layer / polyester. Polarizing plates B101 to B129 on which films were laminated were obtained. In that case, it bonded so that the slow axis of a cellulose-ester film and a polyester film and the absorption axis of a polarizer might become mutually orthogonal.

From the cellulose ester film side of this laminate, using a UV irradiation device with a belt conveyor (the lamp uses a D bulb manufactured by Fusion UV Systems Co., Ltd.), the UV light was irradiated so that the accumulated light amount was 750 mJ / cm ^2. The ultraviolet curable adhesive layer was cured to produce polarizing plates B101 to B129.

[Evaluation of adhesion]
The adhesion of polarizing plates B101 to B129 was evaluated according to the following criteria.

  The operation of peeling off the optical film of the produced polarizing plate from the polarizer was performed 10 times, and the adhesion interface with the optical film / polarizer was visually observed. Thereby, the adhesiveness of the optical film / polarizer was evaluated according to the following criteria.

◎: Even 10 times do not completely peel ○: Not completely peeled, but may peel partially △: Completely peeled 1 to 2 times out of 10 times ×: Completely peeled out 3 times or more out of 10 times The composition of the cellulose ester film and the obtained evaluation results are shown in Table 2 and Table 3 below.

  From the results of Tables 2 and 3, the cellulose ester films 101 to 107, 110, 111, and 113 to 122 that satisfy the constituent requirements of the present invention are both PVA-based water paste and UV curable adhesive in bonding with the polarizer. And the retardation values Re and Rth are in the range of values preferable for the VA mode liquid crystal display device, and thus the visibility is good.

  On the other hand, the cellulose ester films 108 and 109 produced under the production conditions such as filtration temperature, residual solvent amount, stretching speed and the like are outside the preferred range of the present invention have a large standard deviation of the contact angle and adhere to the polarizer. The result was inferior.

  Moreover, the cellulose-ester films 123-127 which used the comparative compound as a retardation raising agent have a low light transmittance of wavelength 320nm, and are inferior to the adhesiveness at the time of using especially an ultraviolet curable adhesive. Moreover, the cellulose-ester films 123-125 with a low retardation value have a low contrast of a liquid crystal display device, and are inferior to visibility.

  Further, as the cellulose ester, the cellulose ester film 112 using DAC with a lower substitution degree is inferior in adhesiveness with a polarizer, and the cellulose ester film 128 using TAC is inferior in adhesiveness with a polarizer, And even if it extends | stretches, since the retardation value is low, the contrast of a liquid crystal display device is low and it is also inferior to visibility. The cellulose ester film 129 that uses DAC as the cellulose ester and does not use the retardation increasing agent is inferior in adhesiveness to the polarizer and has a low retardation value, so that the contrast of the liquid crystal display device is low and the visibility is also inferior. It was a result.

Example 2
[Production of Cellulose Ester Film 201]
A cellulose ester film 201 was produced according to the following method.

(Preparation of dope)
The following components were put into a sealed container and completely dissolved with heating and stirring. The obtained solution was filtered with a filter equipped with a leaf disk filter at a temperature of 50 ° C. (boiling point of dichloromethane + 10 ° C.) to obtain a main dope. The filter medium having a nominal filtration accuracy of 20 μm was used.

<Composition of main dope>
Diacetylserose DAC1 (acetyl group substitution degree: 2.32, weight average molecular weight 270,000) 90 parts by mass Cellulose acetate propionate CAP1 (acetyl group substitution degree: 1.55, propionyl group substitution degree 0.91, total acyl group) Degree of substitution 2.46, weight average molecular weight 280,000) 10 parts by weight Retardation increasing agent (compound having the structure represented by formula (1): Exemplified compound 1-1) 5 parts by weight Sugar ester; BzSc (benzylsucrose : Mixture of compounds a1 to a4 described in Chemical formula 7), average ester substitution degree = 5.5 7 parts by mass Polycondensed ester: polycondensed ester represented by formula (2): P8
5 parts by mass Dichloromethane 430 parts by mass Methanol 11 parts by mass 100 parts by mass of the main dope 1 and 2.5 parts by mass of the inline additive solution prepared in Example 1 were combined with an inline mixer (Toray static type in-tube mixer Hi-Mixer, The dope was obtained by thoroughly mixing with SWJ).

(Film forming process)
The obtained dope was uniformly cast on a stainless steel band support using a belt casting apparatus under the conditions of a dope liquid temperature of 35 ° C. and a width of 1.95 m and a final film thickness of 33 μm. . On the stainless steel band support, the organic solvent in the obtained dope film was evaporated until the residual solvent amount reached 100% by mass to form a web, and then the web was peeled from the stainless steel band support. The obtained web was further pre-dried at 50 ° C. for 3 minutes to obtain a residual solvent amount of 10% by mass, and then the web was reinforced with a tenter at a ratio of 1.4 times the original width in the TD direction at 160 ° C. Stretched. The stretching speed was 300% / min.

  After stretching with a tenter, relaxation was performed at 130 ° C. for 5 minutes, and then drying was completed while the drying zone was being conveyed by a number of rollers. The drying temperature was 130 ° C. and the transport tension was 100 N / m. The obtained film was slit to 2.0 m width, 10 mm wide and 5 μm knurled at both ends of the film, wound on a core of 15.24 cm in inner diameter with an initial tension of 220 N / m and a final tension of 110 N / m. A cellulose ester film 201 having a thickness of 4000 m and a dry film thickness of 25 μm was obtained.

[Production of Cellulose Ester Films 202 to 224]
In the production of the cellulose ester film 201, the type of diacetyl cellulose (DAC) (DAC2 to DAC4), the type of cellulose acetate propionate (CAP) (CAP1 to CAP3), the mixing and mixing ratio of DAC / CAP, DAC / tri Cellulose ester films 202 to 224 were produced in the same manner except that the mixing of acetylcellulose (TAC), the mixing of CAP1 / CAP2 and the film thickness were changed as shown in Table 4.

  Using the produced cellulose ester film, the same evaluation as in Example 1 is performed, and the results are shown in the table.

  From Table 4, the cellulose ester film 201 which contains resin A (DAC) and resin B (CAP) so that the mixing ratio of resin B represented by Formula 1 may be in the range of 10 to 90%. Although 209, 211, 212, 215, and 216 have a film thickness of 25 μm and are thinner than the film prepared in Example 1, they have excellent adhesion to the polarizer and a high retardation value. Also excellent in properties.

  Moreover, from the evaluation result of the cellulose-ester film 218-224 which changed the film thickness of the cellulose-ester film, when the film thickness is in the range of 20-38 μm, the retardation value, the adhesion to the polarizer, the liquid crystal display device It turned out that it was excellent in visibility.

  In contrast, a cellulose ester film 210 using CAP alone, a cellulose ester film 213 that is a mixture of TAC and CAP, a cellulose ester film 214 that is a mixture of two types of CAPs with different substitution degrees, and a cellulose ester film 217 that is a mixture of DAC and TAC. It can be seen that any of the items of retardation, adhesion to the polarizer, and visibility are inferior.

  The cellulose ester film of the present invention is a cellulose ester film having excellent adhesion with both PVA water glue and UV curable adhesive in adhesion to a polarizer, and having a thin film and excellent retardation. , A polarizing plate, a liquid crystal display device, and an organic electroluminescence display device.

DESCRIPTION OF SYMBOLS 1 Melting pot 3, 6, 12, 15 Filter 4, 13 Stock pot 5, 14 Liquid feed pump 8, 16 Conduit 10 Ultraviolet absorber preparation pot 20 Merge pipe 21 Mixer 30 Pressure die 31 Metal belt 32 Web 33 Peeling Position 34 Tenter stretching device 35 Drying device 41 Feeding pot 42 Stock pot 43 Pump 44 Filter

Claims (12)

  A cellulose ester film containing at least a cellulose acetate (resin A) having a substitution degree of acetyl group in the range of 2.1 to 2.6 and a retardation increasing agent, the pure water on the surface of the cellulose ester film The contact angle is in the range of 30 to 75 °, and the standard deviation when the contact angle is measured at 20 points at regular intervals in the film width direction is in the range of 0.05 to 3.0 °. A cellulose ester film having a light transmittance of 80% or more at a wavelength of 320 nm.   The cellulose ester according to claim 1, wherein a standard deviation when the contact angle is measured at 20 points at regular intervals with respect to the width direction of the film is in a range of 0.05 to 1.5 °. the film. The resin A and cellulose acetate propionate (resin B) having a substitution degree of acetyl group of 1.4 to 2.0 and a substitution degree of propionyl group of 0.5 to 1.5, The cellulose ester film according to claim 1, wherein the cellulose ester film is contained so that a mixing ratio of the resin B represented by the following formula 1 is in a range of 10 to 90%.
Formula 1 Mixing ratio of resin B = (mass of resin B) / (mass of resin A + mass of resin B) × 100 (%)   The cellulose ester film according to claim 3, wherein a mixing ratio of the resin B is in a range of 20 to 70%. The cellulose ester film according to claim 3 or 4, wherein an absolute value of a difference in total acyl group substitution degree between the resin A and the resin B satisfies the following formula 2.
Formula 2 | Total acyl group substitution degree of Resin B-Total acyl group substitution degree of Resin A | ≦ 0.3   The film thickness of the said cellulose-ester film exists in the range of 20-38 micrometers, The cellulose-ester film described in any one of Claim 1- Claim 5 characterized by the above-mentioned. The retardation value Re in the in-plane direction of the cellulose ester film represented by the following formula (i) is in the range of 45 to 60 nm, and the retardation value Rth in the film thickness direction represented by the following formula (ii) is It is in the range of 110-140 nm, The cellulose-ester film described in any one of Claim 1- Claim 6 characterized by the above-mentioned.
Formula _{(i): Re = (n} x -n y) × d (nm)
Formula (ii): Rth = {(n _x + n _y ) / 2−n _z } × d (nm)
In (formula (i) and Formula (ii), n _x is .n _y representing the refractive index in the direction x in which the refractive index is maximized in the plane direction of the film in-plane direction of the film, the direction x Represents the refractive index in the direction y orthogonal to _nz , _nz represents the refractive index in the thickness direction z of the film, and d represents the thickness (nm) of the film.) The cellulose ester according to any one of claims 1 to 7, wherein the retardation increasing agent is a nitrogen-containing heterocyclic compound having a structure represented by the following general formula (1). the film.

(In the formula, A represents a pyrazole ring or an imidazole ring. Ar ₁ and Ar ₂ each represent an aromatic hydrocarbon ring or an aromatic heterocyclic ring and may have a substituent. R ₁ represents a hydrogen atom or an alkyl group. An acyl group, a sulfonyl group, an alkyloxycarbonyl group, or an aryloxycarbonyl group, q represents an integer of 1 to 2, and n and m each represents an integer of 1 to 3.   The cellulose ester film according to any one of claims 1 to 8, wherein the retardation increasing agent is contained in a proportion of 0.1 to 5% by mass with respect to the cellulose ester. A method for producing a cellulose ester film for producing a cellulose ester film according to any one of claims 1 to 9,
Preparing a dope by dissolving cellulose ester in a solvent and filtering,
Casting a dope from a casting die onto a support that is a rotationally driven metal endless belt or a rotating drum to form a web;
Peeling the web from the support to form a film,
Stretching and drying the film after peeling,
A step of winding the dried film into a roll,
The dope is filtered using a leaf disc filter at a temperature within the range of (boiling point + 5 ° C.) to (boiling point + 20 ° C.) at 1 atm of the main solvent, and the residual solvent amount is in the range of 2 to 10% by mass. The stretching method defined by the following formula 3 in the width direction of the film is stretched within a range of 250 to 500% / min.
Formula 3 Stretching speed (% / min) = [(d1 / d2) -1] × 100 (%) / t
(In Formula 3, d1 is the width dimension in the stretching direction of the cellulose acylate film after stretching, d2 is the width dimension in the stretching direction of the cellulose acylate film before stretching, and t is the time required for stretching ( min).)   A polarizing plate, wherein the cellulose ester film according to any one of claims 1 to 9 is bonded to a polarizer with water paste.   A polarizing plate, wherein the cellulose ester film according to any one of claims 1 to 9 is bonded to a polarizer with an ultraviolet curable adhesive.

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