JP5927910B2 - Retardation film, method for producing the same, polarizing plate, and liquid crystal display device - Google Patents

Description

  The present invention relates to a retardation film, a production method thereof, a polarizing plate, and a liquid crystal display device, and more specifically, a retardation film produced by casting low-substituted cellulose acetate, a production method thereof, and the retardation film. The present invention relates to a polarizing plate and a liquid crystal display device having the polarizing plate.

  Currently, a retardation film having a specific retardation value and a combination thereof are used for liquid crystal display devices such as televisions and personal computer monitors in order to improve the viewing angle dependency of hue and the front contrast.

  It is known that the retardation film is produced from a synthetic polymer, cellulose ester or the like. Among these, the film made of cellulose ester has the advantage that it can be directly bonded to a polarizer mainly composed of polyvinyl alcohol by saponifying and hydrophilizing the surface with an aqueous alkaline solution. Yes. For this reason, a film made of cellulose ester is widely used as a film to which a retardation compensation function of a polarizer is added (hereinafter also referred to as a retardation film).

  It is known that when cellulose acetate is used as the main raw material for such a retardation film made of cellulose ester, the optical properties of the film depend on the degree of acetyl group substitution of cellulose acetate. In particular, since cellulose acetate with a low degree of substitution has a high intrinsic birefringence, it can be considered that it is possible to achieve high optical expression suitable as a retardation film for VA by reducing the degree of acetyl group substitution. It has been.

  The polarizer bonded with the retardation film as described above is incorporated into the liquid crystal display device together with the liquid crystal cell. At this time, the retardation film is disposed between the polarizer and the liquid crystal cell, and the optical characteristics of the film greatly affect the viewing angle dependency of the hue and the front contrast of the liquid crystal display device. The retardation film is required to exhibit stable optical characteristics against various environmental changes.

  In recent years, with a wider viewing angle and higher image quality of liquid crystal display devices, further improvement in phase difference compensation has been demanded, and further improvement in phase difference compensation has been demanded.

  To reduce the change in Rt (retardation value in the thickness direction) of the cellulose acylate film against changes in the humidity of the usage environment and prevent changes in viewing angle characteristics and hue of the liquid crystal display device due to changes in humidity. For this purpose, Patent Document 1 discloses a relationship between Rt at a humidity of 10% and a humidity of 80%. In order to reduce the variation of Rt due to a change in humidity and satisfy the relationship between humidity and temperature, It has been proposed to introduce a compound having a functional group selected from at least a plurality of hydroxy groups, amino groups, thiol groups, and carboxylic acid groups in one molecule.

  However, the technique described above relates to reducing the variation of Rt with respect to the variation of environmental humidity, and nothing is shown about the performance at the time of shipment of the liquid crystal display device. Further, the cellulose acylate described in Patent Document 1 has a high average degree of acetyl group substitution, and the present situation is that a large retardation required as a retardation film for VA cannot be obtained.

  Further, in Patent Document 2, by adding a polymer derived from a monomer exhibiting negative birefringence to the cellulose ester resin, it is possible to reduce the Rt change after the endurance condition of a temperature of 60 ° C. and a relative humidity of 90%. It is disclosed. However, by introducing the polymer, the change in Rt due to the durability test can be reduced, but nothing is shown about the performance at the time of shipment of the liquid crystal display device. In addition, the addition of the above-described polymer results in low optical development, and the viewing angle of the VA liquid crystal display device is not sufficiently widened. The hue change cannot be prevented and the object cannot be achieved.

  On the other hand, in recent years, demands for cost reduction of retardation films are increasing from the market. As an effective means of cost reduction, there is a method to increase the production speed, but if the film forming speed, stretching speed, drying speed, etc. are increased, the polarizing plate using this retardation film is stored in a high temperature and high humidity environment. It turned out that the light leakage when I did it was great. Moreover, the liquid crystal display device using this polarizing plate has a low contrast, and the hue fluctuation | variation by a viewing angle is seen. Therefore, it is desired to solve these problems while increasing the production speed.

JP 2008-89860 A JP 2010-24424 A

  The present invention has been made in view of the above problems and situations, and the problem to be solved is to reduce the viewing angle dependency, in particular, to prevent the hue due to the viewing angle from changing, and to further improve the front contrast. It is to provide an improved liquid crystal display device. Moreover, it is providing the polarizing plate and retardation film which are used for the liquid crystal display device, and also providing the manufacturing method of this retardation film.

  In order to solve the above-mentioned problems, the present inventor, in the process of examining the cause of the above-mentioned problems, the retardation value in the thickness direction fluctuates greatly from immediately after production to 24 hours after production. When it is large, it has been found that the polarizing plate has a large light leakage when stored at high temperature and high humidity. The present inventor is a retardation film containing cellulose acetate having an average degree of acetyl group substitution in the range of 2.2 to 2.5 based on the above discovery, immediately after the production of the retardation film, A polarizing plate produced using a retardation film characterized in that the change in retardation in the thickness direction within a specific range when placed in a room temperature and humidity environment for 24 hours was stored at high temperature and high humidity. As a result, the present inventors have found that light leakage at the time can be reduced and the hue fluctuation and front contrast of a liquid crystal display device using the retardation film can be improved.

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

［一般式（Ｉ）において、Ｒ^１１及びＲ^１１′は、それぞれ、独立にアルキル基を表す。Ｒ^１２及びＲ^１２′は、それぞれ、独立に水素原子またはベンゼン環に置換可能な基を表す。
Ｘ^１１及びＸ^１１′はそれぞれ独立に水素原子またはベンゼン環に置換可能な基を表す。Ｒ^１１とＸ^１１、Ｒ^１１′とＸ^１１′、Ｒ^１２とＸ^１１、及びＲ^１２′とＸ^１１′は、互いに結合して環を形成してもよい。Ｌは、−Ｓ−又は−ＣＨＲ^１３−を表し、Ｒ^１３は、水素原子またはアルキル基を表す。］

［一般式（II）において、Ｒ^１１〜Ｒ^３５は、それぞれ、独立に、水素原子、アルキル基、アルケニル基、アルキニル基、アリール基、アミノ基、アルコキシ基、アリールオキシ基、アシル基、アルコキシカルボニル基、アリールオキシカルボニル基、アシルオキシ基、アシルアミノ基、アルコキシカルボニルアミノ基、アリールオキシカルボニルアミノ基、スルホニルアミノ基、スルファモイル基、カルバモイル基、アルキルチオ基、アリールチオ基、スルホニル基、スルフィニル基、ウレイド基、リン酸アミド基、ヒドロキシ基、メルカプト基、ハロゲン原子、シアノ基、スルホ基、カルボキシ基、ニトロ基、ヒドロキサム酸基、スルフィノ基、ヒドラジノ基、イミノ基、ヘテロ環基、シリル基を表し、これらの基は無置換であっても置換基を有していてもよく、Ｒ^１１〜Ｒ^３５のうち任意の２つは、互いに結合して環を形成してもよい。Ｘは、ヒドロキシ基を表す。］

［一般式（III）において、Ａ、Ｂ及びＣは芳香環又は芳香族ヘテロ環を表し、Ｌ^１、Ｌ^２及びＬ^３は、−ＮＨ−、−ＮＨＣＯ−及び−ＣＯＮＨ−から選ばれる２価の連結基を表し、Ｘ^１及びＸ^２は炭素原子又は窒素原子を表し、Ｒ^１は置換基を表す。］

［一般式（IV）において、Ａは芳香環又はシクロヘキシル環を表し、Ｒ^１は水素原子又はアルキル基を表し、及びＲ^２は水素原子、アルキル基又はアルコキシ基を表し、ｎは２〜４を表す。］ 1 . A method for producing a retardation film having the following first to sixth steps ,
In the first step, cellulose acetate having an average degree of acetyl group substitution in the range of 2.2 to 2.5 in an organic solvent containing 90% by mass or more of a halogen-based organic solvent, a plasticizer, and the following general formula ( A step of preparing a dope by dissolving the hydrogen bonding compound represented by any one of I) to (IV) ,
The second step is a step of casting the dope on a metal support ,
Third step is a step of forming a film-like product drying the dope was cast,
Fourth step is a step of peeling off the film-like material from the metal support,
Fifth step is a step of stretching said film-like material was peeled,
Sixth step is a step of volatilizing the organic solvent in the film-like material was dried stretched the film-like material,
And,
Immediately before the said film-like material is stretched, in the range of the film-like material × 1.5 The average volatilization rate of the organic solvent ^{10 -3 ~3.0 × 10 -3 g /} (sec · cm 2) Control and further
The film-like material from which the organic solvent has been volatilized in the sixth step is measured at a light wavelength of 590 nm in an environment of 23 ° C. and 55% RH within 0.5 hours immediately after the completion of the sixth step. Retardation value Rt (0.5) in the thickness direction, and after standing for 24 hours in a 23 ° C./55% RH environment immediately after finishing the sixth step, in a 23 ° C./55% RH environment The absolute value | Rt (0.5) −Rt (24) | of the difference from the retardation value Rt (24) in the thickness direction measured at an optical wavelength of 590 nm is controlled to be 2 nm or less. A method for producing a retardation film .

[In General Formula (I), R ¹¹ and R ^{11 ′} each independently represents an alkyl group. R ¹² and R ^{12 ′} each independently represent a hydrogen atom or a group that can be substituted on a benzene ring.
X ¹¹ and X ^{11 ′} each independently represent a hydrogen atom or a group capable of substituting for a benzene ring. R ¹¹ and X ¹¹ , R ^{11 ′} and X ^{11 ′} , R ¹² and X ¹¹ , and R ^{12 ′} and X ^{11 ′} may be bonded to each other to form a ring. L represents —S— or —CHR ¹³ —, and R ¹³ represents a hydrogen atom or an alkyl group. ]

[In General Formula (II), each of R ^{11 to} R ³⁵ independently represents a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an amino group, an alkoxy group, an aryloxy group, an acyl group, or an alkoxycarbonyl group. Group, aryloxycarbonyl group, acyloxy group, acylamino group, alkoxycarbonylamino group, aryloxycarbonylamino group, sulfonylamino group, sulfamoyl group, carbamoyl group, alkylthio group, arylthio group, sulfonyl group, sulfinyl group, ureido group, phosphorus Represents acid amide group, hydroxy group, mercapto group, halogen atom, cyano group, sulfo group, carboxy group, nitro group, hydroxamic acid group, sulfino group, hydrazino group, imino group, heterocyclic group, silyl group, these groups Is unsubstituted It may have a substituent, two of any of R ¹¹ to R ³⁵ may be bonded to each other to form a ring. X represents a hydroxy group. ]

[In General Formula (III), A, B, and C represent an aromatic ring or an aromatic heterocyclic ring, and L ¹ , L ^2, and L ³ are divalent groups selected from —NH—, —NHCO—, and —CONH—. X ¹ and X ² represent a carbon atom or a nitrogen atom, and R ¹ represents a substituent. ]

[In General Formula (IV), A represents an aromatic ring or a cyclohexyl ring, R ¹ represents a hydrogen atom or an alkyl group, and R ² represents a hydrogen atom, an alkyl group or an alkoxy group, and n represents 2 to 4. Represent. ]

2 . The method for producing a retardation film according to item 1, wherein the hydrogen bonding compound is contained within a range of 1 to 10% by mass.

  By the above means of the present invention, a liquid crystal display device with high front contrast can be provided without changing the hue depending on the viewing angle. Moreover, the polarizing plate and retardation film for it can be provided.

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

  The present inventor has found that the retardation film immediately after production is not stable in the orientation of cellulose acetate molecules, and the retardation value in the thickness direction varies even when stored at normal temperature and humidity. By reducing this variation, it is considered that the orientation of cellulose acetate molecules was stabilized from an early stage, and the change in the amount of light leakage could be reduced, thereby improving the front contrast. Further, since the orientation is stable, it is estimated that the orientation fluctuation of the cellulose acetate molecule is small, and the hue variation due to the viewing angle is improved.

It is a figure which shows an example of the laminated constitution of the polarizing plate of this invention.

  The retardation film of the present invention is a retardation film containing cellulose acetate having an average degree of acetyl group substitution in the range of 2.2 to 2.5, and is a final drying step in the production of the retardation film. Within 0.5 hours after the completion, the retardation value Rt (0.5) in the thickness direction measured at a light wavelength of 590 nm in an environment of 23 ° C. and 55% RH, and the final drying step were completed. The absolute value of the difference between the retardation value in the thickness direction measured at a light wavelength of 590 nm under an environment of 23 ° C./55% RH and at a light wavelength of 590 nm after standing at 23 ° C./55% RH for 24 hours. | Rt (0.5) −Rt (24) | is 2 nm or less. This feature is a technical feature common to the inventions according to claims 1 to 8.

  As an embodiment of the present invention, from the viewpoint of obtaining a retardation film having the above | Rt (0.5) −Rt (24) | of 2 nm or less, the tensile elastic modulus in a 23 ° C./55% RH environment is 3500 It is preferable to be within the range of 6000 MPa. Moreover, it is preferable to contain a hydrogen bonding compound in the range of 1 to 10% by mass because the above-mentioned | Rt (0.5) −Rt (24) |

  Furthermore, in this invention, it is preferable that the width | variety of a phase difference film shall be 700-3000 mm. As a result, the production efficiency is high, and the effect that no creaking or breakage occurs during conveyance or winding during production can be obtained.

As a method for producing a retardation film for producing the retardation film of the present invention, cellulose having an average acetyl group substitution degree of 2.2 to 2.5 in an organic solvent containing 90% by mass or more of a halogenated organic solvent is used. A first step of dissolving the acetate to adjust the dope, a second step of casting the dope on a metal support, a third step of drying the cast dope to form a film, the membrane A fourth step of peeling the film from the metal belt, a fifth step of stretching the peeled film, and the organic solvent in the film by drying the stretched film In which the average volatilization rate of the organic solvent of the film-like material is 1.5 × 10 ⁻³ to immediately before the film-like material is stretched. Within the range of 3.0 × 10 ⁻³ g / (sec · cm ² ) It is preferable that the production method having the above-described aspect is that | Rt (0.5) −Rt (24) | can be 2 nm or less.

  The retardation film of the present invention can be suitably included in a polarizing plate and a liquid crystal display device.

  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.

(Retardation film)
The retardation film of the present invention (hereinafter also referred to as the film of the present invention) is a retardation film containing cellulose acetate having an average degree of acetyl group substitution in the range of 2.2 to 2.5, Retardation value Rt (0.5) in the thickness direction measured at an optical wavelength of 590 nm within an environment of 23 ° C. and 55% RH within 0.5 hours after the final drying step of the production of the retardation film And a retardation value in the thickness direction measured at a light wavelength of 590 nm in a 23 ° C./55% RH environment after standing for 24 hours in a 23 ° C./55% RH environment after the final drying step. The absolute value | Rt (0.5) −Rt (24) | of the difference from Rt (24) is 2 nm or less.

  In the polarizing plate using the retardation film of the present invention, the change in the amount of light leakage is suppressed, and in the liquid crystal display device using the polarizing plate, the front contrast is improved and the hue fluctuation due to the viewing angle is improved.

(Cellulose acetate)
First, the cellulose acetate preferably used in the present invention will be described in detail.

  Examples of the raw material cellulose of the cellulose acetate according to the present invention include cotton linter and wood pulp (hardwood pulp, softwood pulp), etc., but any cellulose acetate obtained from any raw material cellulose can be used. May be.

  In particular, the cellulose acetate preferred in the present invention is preferably obtained from wood pulp from the viewpoint of pasting with a polarizer.

  Glucose units having β-1,4 bonds constituting cellulose have free hydroxy groups (hydroxyl groups) at the 2nd, 3rd and 6th positions. Cellulose acetate is a polymer obtained by acetylating part or all of these hydroxy groups (hydroxyl groups) with acetyl groups. The degree of acetyl group substitution means the proportion of cellulose acetylated (hydroxyl group) located at the 2nd, 3rd and 6th positions (100% acetylation has a degree of substitution of 3).

  The cellulose acetate used in the present invention is not particularly defined as long as the average degree of acetyl group substitution is in the range of 2.2 to 2.5. When a mixture of cellulose acetates having different degrees of acetyl group substitution is used, the sum of the products of the degree of acetyl group substitution and the mass fraction of each cellulose acetate is called the average degree of acetyl group substitution. The average substitution degree can be measured from the area ratio of the chart showing the substitution degree distribution by high performance liquid chromatography by a conventional method.

  In the acetylation of cellulose in the present invention, when an acid anhydride or acid chloride is used as an acetylating agent, an organic acid such as acetic acid or methylene chloride is used as an organic solvent as a reaction solvent. .

As the catalyst, when the acetylating agent is an acid anhydride, a protic catalyst such as sulfuric acid is preferably used, and when the acetylating agent is an acid chloride (for example, CH ₃ COCl), a basic catalyst is used. A compound is used.

  The most common industrial synthesis method of cellulose fatty acid ester contains fatty acid corresponding to acetyl group and other acyl groups (acetic acid, propionic acid, valeric acid, etc.) or their anhydrides This is a method of acylating with a mixed organic acid component.

  The cellulose acetate used for this invention is compoundable by the method described in Unexamined-Japanese-Patent No. 10-45804, for example.

(Halogen organic solvent)
As the halogen-based organic solvent according to the present invention, a solvent selected from halogenated hydrocarbons having 1 to 6 carbon atoms is preferable because it well dissolves cellulose acetate. Particularly preferred halogenated organic solvents include dichloromethane, chloroform, dichloroethane and the like.

(Organic solvent)
The cellulose acetate which concerns on this invention melt | dissolves in the organic solvent containing 90 mass% or more of halogen-type organic solvents, and adjusts dope. The organic solvent other than the halogen-based organic solvent is selected from alcohols or hydrocarbons having 1 to 10 carbon atoms, and more preferably alcohols having 1 to 8 carbon atoms.

  The alcohol may be linear, branched or cyclic, and is preferably a saturated aliphatic hydrocarbon. The hydroxy group of the alcohol may be any of primary to tertiary. Examples of the alcohol include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, tert-butanol, 1-pentanol, 2-methyl-2-butanol and cyclohexanol.

  In addition, both aromatic hydrocarbons and aliphatic hydrocarbons can be used. Examples of hydrocarbons include cyclohexane, hexane, benzene, toluene and xylene.

(Retardation retardation value Rt)
Rt (λ) has an in-plane slow axis (determined by KOBRA 21ADH) as a tilt axis (rotary axis) (if there is no slow axis, an arbitrary direction in the film plane is taken as the rotational axis). With respect to the normal direction of the film, light at a wavelength of λ nm is incident in 10 degree steps from the normal direction to 50 degrees on one side, and a total of 6 points are measured, and the measured retardation value and average KOBRA 21ADH calculates based on the assumed value of refractive index and the input film thickness value. In the present specification, Rt is a value measured under an environment of 23 ° C. and 55% RH when the wavelength λ is 590 nm unless otherwise specified.

  The retardation value in the thickness direction of the retardation film is obtained by the following formula.

Rt = [(n _x + _ny ) / 2−n _z ] × d
[In the formula, Rt is the retardation value in the thickness direction of the retardation film as measured at a light wavelength of 590 nm. (N _x is a refractive index in a slow axis direction in the film plane, n _y is a refractive index in a fast axis direction in the film plane, n _z is a refractive index in the thickness direction of the film , D is the thickness of the film.

(Elastic modulus)
The film of the present invention preferably has an elastic modulus of 3000 MPa or more, more preferably 3000 to 7000 MPa, and particularly preferably 3500 to 6000 MPa. The “elastic modulus” is a value obtained by conditioning the sample for 24 hours in an environment of 23 ° C. and 55% RH and measuring the elastic modulus according to the method described in JIS K7127. Tensilon manufactured by Orientec Co., Ltd. is used as the tensile tester.

(Method for producing retardation film)
The production of the retardation film of the present invention by the solution casting method is the first step of preparing a dope by dissolving cellulose acetate and additives in a solvent, on an endless metal support that transfers the dope indefinitely. A second step of casting, a third step of drying the cast dope to form a film, a fourth step of peeling from the metal support, a fifth step of stretching or maintaining the width, and further heating and It is preferably carried out by the sixth step of drying and volatilizing the organic solvent in the film-like material.

(First step)
The process for preparing the dope will be described. The concentration of cellulose acetate in the dope is preferably higher because the drying load after casting on the metal support can be reduced. However, if the concentration of cellulose acetate is too high, the load during filtration increases and the filtration accuracy is poor. Become. As a density | concentration which makes these compatible, 10-35 mass% is preferable, More preferably, it is 15-25 mass%.

  The solvent used for the dope contains 90% by mass or more of a halogen-based organic solvent which is a good solvent. Although the solvent may be used alone or in combination of two or more, it is preferable from the viewpoint of production efficiency to use a mixture of a halogen-based organic solvent and a poor solvent of cellulose acetate.

  With a good solvent and a poor solvent, what dissolve | melts the cellulose acetate to be used independently is defined as a good solvent, and what does not swell or dissolve independently is defined as a poor solvent.

Therefore, depending on the average acetylation degree (acetyl group substitution degree) of cellulose acetate,
The poor solvent changes.

The good solvent used in the present invention is not particularly limited, but is an organic halogen solvent such as methylene chloride.

Moreover, although the poor solvent used for this invention is not specifically limited, For example, methanol, ethanol, n-butanol, cyclohexane, cyclohexanone, etc. are used preferably. Moreover, it is preferable that 0.01-2 mass% of water contains in dope.

Moreover, the solvent used for melt | dissolution of a cellulose acetate collect | recovers the solvent removed from the film by drying at the film-forming process, and uses this again.

The recovery solvent may contain trace amounts of additives added to cellulose acetate, such as plasticizers, UV absorbers, polymers, monomer components, etc., but these are preferably reused even if they are included. Can be purified and reused if necessary.

  Various additives (for example, plasticizers, ultraviolet inhibitors, deterioration inhibitors, fine particles, optical property modifiers, etc.) according to the application can be added to the dope in which the cellulose acetate according to the present invention is dissolved. Moreover, although the addition time may be added in any of the dope preparation steps, it may be added by adding a preparation step to the final preparation step of the dope preparation step.

As a method for dissolving cellulose acetate when preparing the dope described above, a general method can be used. When heating and pressurization are combined, it is possible to heat above the boiling point at normal pressure.

It is preferable to stir and dissolve while heating at a temperature that is equal to or higher than the boiling point of the solvent at normal pressure and that the solvent does not boil under pressure, in order to prevent the generation of massive undissolved materials called gels and mamacos.

Further, a method in which cellulose acetate is mixed with a poor solvent and wetted or swollen, and then a good solvent is added and dissolved is also preferably used.

The pressurization may be performed by a method of injecting an inert gas such as nitrogen gas or a method of increasing the vapor pressure of the solvent by heating. Heating is preferably performed from the outside. For example, a jacket type is preferable because temperature control is easy.

The heating temperature with the addition of a solvent is preferably higher from the viewpoint of the solubility of cellulose acetate, but if the heating temperature is too high, the required pressure increases and the productivity deteriorates.

A preferable heating temperature is 45 to 120 ° C, more preferably 60 to 110 ° C, and 70 ° C to
105 ° C. is more preferable. The pressure is adjusted so that the solvent does not boil at the set temperature.

Alternatively, a cooling dissolution method is also preferably used, whereby cellulose acetate can be dissolved in a solvent such as methyl acetate.

Next, this cellulose acetate solution is filtered using a suitable filter medium such as filter paper. As the filter medium, it is preferable that the absolute filtration accuracy is small in order to remove insoluble matters and the like, but there is a problem that the filter medium is likely to be clogged if the absolute filtration accuracy is too small.

For this reason, a filter medium having an absolute filtration accuracy of 0.008 mm or less is preferable, and 0.001 to 0.008.
A filter medium of mm is more preferable, and a filter medium of 0.003 to 0.006 mm is still more preferable.

There are no particular restrictions on the material of the filter medium, and ordinary filter media can be used. However, plastic filter media such as polypropylene and Teflon (registered trademark), and metal filter media such as stainless steel do not drop off fibers. preferable.

It is preferable to remove and reduce impurities, particularly bright spot foreign matter, contained in the raw material cellulose acetate by filtration.

The bright spot foreign matter is arranged in a crossed Nicols state with two polarizing plates, a retardation film or the like is placed between them, light is applied from one polarizing plate side, and observation is performed from the other polarizing plate side. It is a point (foreign matter) where light from the opposite side sometimes leaks, and the number of bright spots having a diameter of 0.01 mm or more is preferably 200 / cm ² or less.

More preferably, it is 100 pieces / cm < ² > or less, More preferably, it is 50 pieces / m < ² > or less, More preferably, it is 0-10 pieces / cm < ² > or less. Further, it is preferable that the number of bright spots of 0.01 mm or less is small.

The dope can be filtered by a normal method, but the method of filtering while heating at a temperature not lower than the boiling point of the solvent at normal pressure and in a range where the solvent does not boil under pressure is the filtration pressure before and after filtration. The increase in the difference (referred to as differential pressure) is small and preferable.

A preferred temperature is 45 to 120 ° C, more preferably 45 to 70 ° C, and still more preferably 45 to 55 ° C.

A smaller filtration pressure is preferred. The filtration pressure is preferably 1.6 MPa or less, 1.2M
It is more preferably Pa or less, and further preferably 1.0 MPa or less.

(Second step)
Here, the dope casting will be described.

The metal support in the casting process is preferably a mirror finished surface,
As the metal support, a stainless steel belt or a drum whose surface is plated with a casting is preferably used.

  The cast width can be 1 to 4 m. The surface temperature of the metal support in the casting step is −50 ° C. to a temperature lower than the boiling point of the solvent, and a higher temperature is preferable because the web can be dried faster. May deteriorate.

  A preferable support temperature is 0 to 55 ° C, and more preferably 25 to 50 ° 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 hot 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 warm air is used, wind at a temperature higher than the target temperature may be used.

(Third step)
The process of drying the film-like material on the metal support will be described.

  As described above, the temperature of the metal support is controlled, and drying is performed to the residual solvent amount suitable for the fourth step on the metal support by applying drying air adjusted in temperature.

  The drying of the dope on the support is generally performed by applying hot air from the surface side of the support (drum or belt), that is, the surface of the web on the support, or applying hot air from the back surface of the drum or belt, There is a liquid heat transfer method in which the temperature controlled liquid is contacted from the back side opposite to the belt or drum dope casting surface and the drum or belt is heated by heat transfer to control the surface temperature. The method is preferred. The surface temperature of the support before casting may be any number as long as it is not higher than the boiling point of the solvent used for the dope. However, in order to promote drying and to lose fluidity on the support, the temperature may be set to 1 to 10 ° C lower than the boiling point of the lowest boiling solvent used. preferable.

(Fourth process)
The fourth step of peeling the film-like material from the metal support will be described. The fourth step includes an operation of drying the solvent in the film-like material to a state suitable for stretching, if necessary, after peeling the film from the metal support.

  In order for the retardation film to exhibit good planarity, the residual solvent amount when peeling the web from the metal support is preferably 10 to 150% by mass, more preferably 20 to 40% by mass or 60 to 130% by mass. Especially preferably, it is 20-30 mass% or 70-120 mass%.

  In the present invention, the amount of residual solvent is defined by the following formula.

Residual solvent amount (% by mass) = {(MN) / N} × 100
M is the mass of a sample collected during or after the production of the web or film, and N is the mass after heating M at 115 ° C. for 1 hour.

  It is preferable to peel at a peeling tension of 300 N / m or less while stretching in the width direction (lateral direction) by a tenter method in which both ends of the web are gripped by clips or the like.

  During the fourth step, it is preferable to dry the film-like material after peeling from the support. In this drying, the film tends to shrink in the width direction due to evaporation of the solvent. Shrinkage increases with drying at higher temperatures. Drying while suppressing this shrinkage as much as possible is preferable for improving the flatness of the finished film. From this point, for example, a method of drying the entire drying process or a part of the process as shown in Japanese Patent Application Laid-Open No. 62-46625 while holding the width at both ends of the web with a clip in the width direction (tenter method) ) Is preferred.

(Fifth step)
In order to obtain the target retardation value Rt, it is preferable that the retardation film further controls the refractive index by controlling the transport tension and stretching. Hereinafter, the stretching process will be described.

For example, the retardation value can be adjusted by decreasing or increasing the tension in the longitudinal direction.

Further, biaxial stretching or uniaxial stretching can be performed sequentially or simultaneously with respect to the longitudinal direction (film forming direction) of the film and the direction orthogonal to the longitudinal direction of the film, that is, the width direction.

The draw ratios in the biaxial directions perpendicular to each other are finally 0 to 1.5 in the casting direction.
It is preferable that the range is 1.1 to 2.5 times in the width direction and 0 to 1.0 in the casting direction.
It is preferable to carry out in the range of 1.2 to 2.0 times in the width direction.

The temperature immediately before stretching is preferably 140 to 170 ° C. The stretching temperature is preferably 120 ° C. to 200 ° C., more preferably 150 ° C. to 200 ° C., and more preferably 150 ° C. to 190 ° C. or less.

The residual solvent in the film is preferably 20 to 0%, more preferably 15 to 0%.

Specifically, the residual solvent is stretched by 11% at 155 ° C., or the residual solvent is 2 at 155 ° C.
% Is preferred. Alternatively, it is preferable that the residual solvent is stretched at 11% at 160 ° C, or the residual solvent is stretched at less than 1% at 160 ° C.

There is no particular limitation on the method of stretching the web. For example, a method in which a difference in peripheral speed is applied to a plurality of rolls, and the roll peripheral speed difference is used to stretch in the longitudinal direction between the rolls. And a method of stretching in the vertical direction, a method of stretching in the horizontal direction and stretching in the horizontal direction, a method of stretching in the vertical and horizontal directions and stretching in both the vertical and horizontal directions, and the like. Of course, these methods may be used in combination.

In the case of the so-called tenter method, driving the clip portion by the linear drive method is preferable because smooth stretching can be performed and the risk of breakage and the like can be reduced.

These width maintenance or lateral stretching in the film forming step is preferably performed by a tenter, and may be a pin tenter or a clip tenter.

(Sixth step)
By passing the drying process after being stretched before being stretched, the residual solvent amount suitable for the subsequent manufacturing process of the polarizing plate and the manufacturing process of the liquid crystal display device can be adjusted.

  The drying temperature in the drying step of the film-like product is preferably 40 to 250 ° C, particularly preferably 70 to 180 ° C. Further, in order to remove the residual solvent, it is preferably used to dry at 50 to 160 ° C., and in that case, the residual solvent is evaporated by drying with high-temperature air whose temperature is changed successively. The above method is described in Japanese Patent Publication No. 5-17844. According to this method, it is possible to shorten the time from casting to stripping. The drying temperature, the amount of drying air, and the drying time vary depending on the solvent used, and may be appropriately selected according to the type and combination of the solvents used. The amount of residual solvent in the final finished film is preferably 2% by mass or less, and more preferably 0.4% by mass or less in order to obtain a film having good dimensional stability.

  In the present invention, ending the final drying step of the production of the retardation film means a state immediately before winding. It is because it is not influenced by drying by being wound up.

  The winding machine relating to the production of the retardation film of the present invention may be a commonly used winding method such as a constant tension method, a constant torque method, a taper tension method, a program tension control method with a constant internal stress. Can be rolled up. The thickness (after drying) of the cellulose acetate film of the present invention varies depending on the purpose of use, but is usually in the range of 10 to 500 μm, more preferably in the range of 20 to 200 μm, and most preferably in the range of 30 to 80 μm. . The film thickness may be adjusted by adjusting the solid content concentration contained in the dope, the slit gap of the die base, the extrusion pressure from the die, the support speed, and the like so as to obtain a desired thickness.

(Average volatilization rate)
Cut out a total of three 30cm4 samples from the left, center, and right in the width direction from the film-like material just before being stretched, and immediately place each on a hot plate placed in a sealed container that does not have a blowing function. The mass reduction amount after 20 seconds (Ag) and the mass reduction amount after 40 seconds (Bg) were measured, and the volatilization rate was calculated from the equation of “(Ag−Bg) / 20 sec · 900 cm ² ” (g / sec・ Determined in cm ² ).
The hot plate was adjusted to a temperature just before the film-like material was stretched, and the capacity of the sealed container was set to 0.1 m ³ . Further, the temperature immediately before the stretching is preferably in the range of 140 to 170 ° C.

Here, the term “immediately before stretching” refers to a state before the stretching is actually started in the fifth step if there is time until the stretching actually starts in the fifth step. Moreover, when extending | stretching starts simultaneously with entering a 5th process, it will be immediately before extending | stretching the last state of a 4th process. The average volatilization rate is an average of volatilization rates of the three samples, and is expressed in units of g / (sec · cm ² ) (a mass reduction rate per unit area).
In particular, a film formed from a dope using a dope prepared by dissolving cellulose acetate having an average acetyl group substitution degree of 2.2 to 2.5 in an organic solvent containing 90% by mass or more of a halogen-based organic solvent An optical film produced by setting the average volatilization rate immediately before stretching the material within the range of 1.5 × 10 ^{−3 to} 3.0 × 10 ⁻³ g / (sec · cm ² ) is used for a liquid crystal display. This is preferable because the hue variation of the apparatus is small and the front contrast is high.

(Hydrogen bonding compound)
As a result of the study by the present inventors, in the retardation film, reducing the change in retardation value from immediately after production to 24 hours prevents the change in hue due to the viewing angle of the liquid crystal display device and improves the front contrast. It was found to be important in doing so.

  In order to suppress the retardation value fluctuation, it was necessary to suppress the fluctuation of the orientation of the cellulose acetate molecule, and for this reason, it was considered necessary to increase the intermolecular hydrogen bond of the cellulose acetate. In order to increase the hydrogen bond, the degree of acetyl group substitution may be decreased, but a desired retardation value cannot be obtained. In order to obtain expression of a desired retardation value, it is necessary to increase the degree of acetyl group substitution. However, in order to bring the variation in retardation value to a desired region, hydrogen bonds need to be in a specific range. . The present inventor has found that it is effective to add a hydrogen bonding compound in order to bring the hydrogen bond into a specific range, and suppressing the fluctuation of the retardation value by adding the hydrogen bonding compound. I found it possible.

  Hydrogen bonding is described in J. Org. N. As described in Israel Ativili, “Intermolecular Forces and Surface Forces” (Takeshi Kondo, Hiroyuki Oshima, Maglow Hill Publishing, 1991), hydrogen atoms covalently bonded to electrically negative atoms are electrically Is a non-covalent attractive interaction with a lone pair of electrons such as π-electron system (oxygen, nitrogen, fluorine, chlorine) and a hydrogen bond compound. And a compound having a hydrogen atom covalently bonded. For example, it refers to a compound that can form a hydrogen bond with an adjacent lone pair of electrons by including OH (oxygen hydrogen bond), NH (nitrogen hydrogen bond), and the like.

  As the hydrogen bonding compound according to the present invention, compounds represented by the following general formulas (I) to (V) are preferable.

前記一般式（Ｉ）において、
Ｒ¹¹及びＲ^11′は各々独立に置換又は無置換の炭素数１〜２０のアルキル基であることが好ましい。 [Hydrogen Bonding Compound of General Formula (I)]

In the general formula (I),
R ¹¹ and R ^{11 ′} are preferably each independently a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms.

R ¹¹ and R ^{11 ′} are more preferably a primary, secondary or tertiary alkyl group having 1 to 15 carbon atoms, specifically a methyl group, an isopropyl group, a t-butyl group, a t-amyl group, Examples include t-octyl group, cyclohexyl group, cyclopentyl group, 1-methylcyclohexyl group, 1-methylcyclopropyl group and the like. R ¹¹ and R ^{11 ′} are more preferably an alkyl group having 1 to 8 carbon atoms, and among them, a methyl group, a t-butyl group, a t-amyl group, or a 1-methylcyclohexyl group is more preferable, and a methyl group, t- A butyl group is most preferred.

  The substituent of the alkyl group is not particularly limited, but preferably an aryl group, a hydroxy group, an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, an acylamino group, a sulfonamido group, a sulfonyl group, a phosphoryl group. An acyl group, a carbamoyl group, an ester group, a ureido group, a urethane group, and a halogen atom.

R ¹² and R ^{12 ′} each independently represent a hydrogen atom or a group capable of substituting for a benzene ring, preferably an alkyl group having 1 to 20 carbon atoms, specifically, methyl, ethyl, propyl, butyl Group, isopropyl group, t-butyl group, t-amyl group, cyclohexyl group, 1-methylcyclohexyl group, benzyl group, methoxymethyl group, and methoxyethyl group. More preferred are a methyl group, an ethyl group, a propyl group, an isopropyl group, or a t-butyl group, and particularly preferred are a methyl group and an ethyl group.

X ¹¹ and X ^{11 ′} each independently represent a hydrogen atom or a group capable of substituting for a benzene ring, preferably a hydrogen atom, a halogen atom or an alkyl group, more preferably a hydrogen atom.

  The group that can be substituted on the benzene ring is preferably an alkyl group, an aryl group, a halogen atom, an alkoxy group, or an acylamino group.

L represents —S— or —CHR ¹³ —, preferably —CHR ¹³ —.

R ¹³ is preferably a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, more preferably represents a hydrogen atom or an alkyl group having 1 to 15 carbon atoms.

  As the alkyl group, in addition to a chain alkyl group, a cyclic alkyl group is also preferably used. Moreover, what has a C = C bond in these alkyl groups can also be used preferably. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a 2,4,4-trimethylpentyl group, a cyclohexyl group, a 2,4-dimethyl-3-cyclohexenyl group, or 3,5-dimethyl-3. -A cyclohexenyl group and the like are preferable. R13 is particularly preferably a hydrogen atom, a methyl group, an ethyl group, a propyl group, an isopropyl group, or a 2,4-dimethyl-3-cyclohexenyl group.

The alkyl group may have a substituent. Preferable specific examples of the alkyl group include methyl group, ethyl group, propyl group, butyl group, heptyl group, undecyl group, isopropyl group, 1-ethylpentyl group, 2,4,4-trimethylpentyl group, cyclohexyl group, Examples include 2,4-dimethyl-3-cyclohexenyl group and 3,5-dimethyl-3-cyclohexenyl group. Examples of the substituent of the alkyl group are the same as the substituent of R ¹¹ , and are a halogen atom, alkoxy group, alkylthio group, aryloxy group, arylthio group, acylamino group, sulfonamido group, sulfonyl group, phosphoryl group, oxycarbonyl group, Examples thereof include a carbamoyl group and a sulfamoyl group.

When R ¹¹ and R ^{11 '} are tertiary alkyl groups and R ¹² and R ^12' are methyl groups, R ¹³ is a primary or secondary alkyl group having 1 to 8 carbon atoms (methyl group, ethyl group). , A propyl group, an isopropyl group, or a 2,4-dimethyl-3-cyclohexenyl group).

When R ¹¹ and R ^{11 ′} are tertiary alkyl groups and R ¹² and R ^{12 ′} are alkyl groups other than methyl groups, R ¹³ is preferably a hydrogen atom.

When R ¹¹ and R ^{11 ′} are not a tertiary alkyl group, R ¹³ is preferably a hydrogen atom or a secondary alkyl group, and particularly preferably a secondary alkyl group. Preferred groups as the secondary alkyl group for R ¹³ are isopropyl group and 2,4-dimethyl-3-cyclohexenyl group.

  X represents C—R (R represents a hydrogen-bonding substituent). X is preferably an amino group, an acylamino group, an alkoxycarbonylamino group, an aryloxycarbonylamino group, a sulfonylamino group, a hydroxy group, a mercapto group, or a carboxy group, and more preferably a hydroxy group.

  Specific examples of the compound represented by the general formula (I) are given below, but the present invention is not limited to the following specific examples.

〔一般式（II）の水素結合性化合物〕

前記一般式（II）において、
Ｒ¹¹、Ｒ^1２、Ｒ^1３、Ｒ^1４、Ｒ^1５、Ｒ^２１、Ｒ^２２、Ｒ^２３、Ｒ^２４、Ｒ^２５、Ｒ^３１、Ｒ^３２、Ｒ^３３、Ｒ^３４及びＲ^３５は、それぞれ独立に、水素原子または置換基を表す。置換基としては後述の置換基Ｔが適用できる。

[Hydrogen bonding compound of general formula (II)]

In the general formula (II),
R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ , R ²¹ , R ²² , R ²³ , R ²⁴ , R ²⁵ , R ³¹ , R ³² , R ³³ , R ³⁴ and R ³⁵ are each independently Represents a hydrogen atom or a substituent. Substituent T described later can be applied as the substituent.

R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ , R ²¹ , R ²² , R ²³ , R ²⁴ , R ²⁵ , R ³¹ , R ³² , R ³³ , R ³⁴ and R ³⁵ are preferably alkyl groups. Alkenyl group, alkynyl group, aryl group, substituted or unsubstituted amino group, alkoxy group, aryloxy group, acyl group, alkoxycarbonyl group, aryloxycarbonyl group, acyloxy group, acylamino group, alkoxycarbonylamino group, aryloxy Carbonylamino group, sulfonylamino group, sulfamoyl group, carbamoyl group, alkylthio group, arylthio group, sulfonyl group, sulfinyl group, ureido group, phosphoric acid amide group, hydroxy group, mercapto group, halogen atom (for example, fluorine atom, chlorine atom, Bromine atom, iodine atom), cyano group, Rufo group, carboxy group, nitro group, hydroxamic acid group, sulfino group, hydrazino group, imino group, heterocyclic group (preferably having 1 to 30 carbon atoms, more preferably 1 to 12 carbon atoms. Atoms, oxygen atoms, sulfur atoms, specifically imidazolyl, pyridyl, quinolyl, furyl, piperidyl, morpholino, benzoxazolyl, benzimidazolyl, benzthiazolyl, etc.), and silyl groups, more preferably alkyl. Group, aryl group, substituted or unsubstituted amino group, alkoxy group and aryloxy group, more preferably alkyl group, aryl group and alkoxy group.

  These substituents may be further substituted. Moreover, when there are two or more substituents, they may be the same or different. If possible, they may be linked together to form a ring.

  Specific examples of the compound represented by the general formula (II) are given below, but the present invention is not limited to the following specific examples.

〔一般式（III）の水素結合性化合物〕

前記一般式（III）において、
Ａ、Ｂ及びＣは芳香族環又は芳香族ヘテロ環を表し、Ｌ^１、Ｌ^２及びＬ^３は、−ＮＨ−、−ＮＨＣＯ−及び−ＣＯＮＨ−から選ばれる２価の連結基を表し、Ｘ^１及びＸ^２は炭素原子又は窒素原子を表し、Ｒ^１は置換基を表す。

[Hydrogen bonding compound of general formula (III)]

In the general formula (III),
A, B and C represent an aromatic ring or an aromatic heterocycle, L ¹ , L ² and L ³ represent a divalent linking group selected from —NH—, —NHCO— and —CONH—, and X ¹ and X ² represent a carbon atom or a nitrogen atom, and R ¹ represents a substituent.

  Examples of the aromatic ring represented by A, B and C include a benzene ring and a naphthalene ring, and examples of the aromatic heterocycle include a pyridine ring, a pyrimidine ring and a pyrazine ring.

R ¹ is an alkyl group (for example, methyl group, ethyl group, propyl group, isopropyl group, t-butyl group, pentyl group, hexyl group, octyl group, dodecyl group, trifluoromethyl group, etc.), cycloalkyl group ( For example, cyclopropyl group, cyclopentyl group, cyclohexyl group, adamantyl group, etc.), aryl group (eg, phenyl group, naphthyl group, etc.), heterocyclic group (eg, pyridyl group, pyrimidyl group, oxazolyl group, thiazolyl group, oxadiazolyl group) , Thiadiazolyl group, imidazolyl group etc.), acylamino group (eg acetylamino group, benzoylamino group etc.), alkylthio group (eg methylthio group, ethylthio group etc.), arylthio group (eg phenylthio group, naphthylthio group etc.), An alkenyl group (for example, a vinyl group, 2-propenyl group, 3-butenyl group, 1-methyl-3-propenyl group, 3-pentenyl group, 1-methyl-3-butenyl group, 4-hexenyl group, cyclohexenyl group, styryl group, etc.), halogen atom ( For example, fluorine atom, chlorine atom, bromine atom, iodine atom etc.), alkynyl group (eg propargyl group etc.), alkylsulfonyl group (eg methylsulfonyl group, ethylsulfonyl group etc.), arylsulfonyl group (eg phenylsulfonyl) Group, naphthylsulfonyl group, etc.), alkylsulfinyl group (eg, methylsulfinyl group, etc.), arylsulfinyl group (eg, phenylsulfinyl group, etc.), phosphono group, acyl group (eg, acetyl group, pivaloyl group, benzoyl group, etc.) Carbamoyl group (for example, aminocarbonyl group, methyl Aminocarbonyl group, dimethylaminocarbonyl group, butylaminocarbonyl group, cyclohexylaminocarbonyl group, phenylaminocarbonyl group, etc.), sulfamoyl group (for example, aminosulfonyl group, methylaminosulfonyl group, dimethylaminosulfonyl group, butylaminosulfonyl group, Hexylaminosulfonyl group, cyclohexylaminosulfonyl group, octylaminosulfonyl group, dodecylaminosulfonyl group, phenylaminosulfonyl group, naphthylaminosulfonyl group, 2-pyridylaminosulfonyl group, etc.), sulfonamide group (for example, methanesulfonamide group, benzene) Sulfonamide group etc.), cyano group, alkyloxy group (eg methoxy group, ethoxy group, propoxy group etc.), aryloxy group (eg phenoxy group) Xy group, naphthyloxy group, etc.), siloxy group, acyloxy group (eg, acetyloxy group, benzoyloxy group, etc.), sulfonic acid group, sulfonic acid salt, aminocarbonyloxy group, amino group (eg, amino group, ethyl group) Amino group, dimethylamino group, butylamino group, cyclopentylamino group, 2-ethylhexylamino group, dodecylamino group, etc.), anilino group (for example, phenylamino group, chlorophenylamino group, toluidino group, anisidino group, naphthylamino group, 2-pyridylamino group, etc.), imide group, ureido group (for example, methylureido group, ethylureido group, pentylureido group, cyclohexylureido group, octylureido group, dodecylureido group, phenylureido group, naphthylureido group, 2-pyridylamino group) Urei Group), alkoxycarbonylamino group (eg methoxycarbonylamino group, phenoxycarbonylamino group etc.), alkoxycarbonyl group (eg methoxycarbonyl group, ethoxycarbonyl group, phenoxycarbonyl etc.), aryloxycarbonyl group (eg Phenoxycarbonyl group etc.), carbamate group (eg methyl carbamate group, phenyl carbamate group), alkyloxyphenyl group (eg methoxyphenyl group etc.), acyloxyphenyl group (eg acetyloxyphenyl group etc.), thioureido group, carboxy Represents a group, a salt of a carboxylic acid, a hydroxy group, a mercapto group, or a nitro group. A plurality of these substituents may be further substituted with the same group, and adjacent substituents may be bonded to form a ring.

R ¹ in the general formula (III) is an alkyl group, an alkyloxy group having 4 or less carbon atoms, an aryloxy group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a carbamate group, a carbonate group, a hydroxy group, or a cyano group. Group, an amino group is preferable, an alkyloxy group having 4 or less carbon atoms, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a carbamate group, and an amino group are more preferable, and an alkyloxy group, an acyl group, and an alkoxy group having 4 or less carbon atoms. A carbonyl group, aryloxycarbonyl group, carbamate group, and carbonate group are particularly preferred. By having these substituents, retardation expression and solubility are improved.

Is not particularly limited as substitution position of R ¹ in the general formula (III), to litter in terms of retardation-expressing, if A and B and C is 6-membered ring L ^1, L ² and L ³ The para and meta positions are preferred.

A plurality of R ¹ in the general formula (III) may be substituted, and they may be the same or different from each other. The preferred number of substituents is 1 to 3.

X ¹ and X ² in the general formula (III) represent a carbon atom or a nitrogen atom, and may be different or the same.

  Specific examples of the compound represented by the general formula (III) are shown below, but the present invention is not limited to the following specific examples.

〔一般式（IV）の水素結合性化合物〕

前記一般式（IV）において、Ａは芳香族環もしくはシクロヘキシル環を表し、芳香族環としてはベンゼン環、ナフタレン環、等が挙げられる。

[Hydrogen bonding compound of general formula (IV)]

In the general formula (IV), A represents an aromatic ring or a cyclohexyl ring, and examples of the aromatic ring include a benzene ring and a naphthalene ring.

R ¹ represents a hydrogen atom or an alkyl group, and R ² represents a hydrogen atom, an alkyl group or an alkoxy group. When R ¹ or R ² is an alkyl group, the alkyl group is preferably a methyl group, an ethyl group or a propyl group. When R ² is an alkoxy group, the alkoxy group is preferably a methoxy group, an ethoxy group, or a propoxy group, and a plurality of R ² can be substituted on one ring A, and R ² substituted on one ring A Is preferably 1 to 3. n represents 1-4.

  Specific examples of the compound represented by the general formula (IV) are given below, but the present invention is not limited to the following specific examples.

〔一般式（Ｖ）の水素結合性化合物〕

前記一般式（Ｖ）において、Ｒ^１、Ｒ^２及びＲ^３は水素原子、アルキル基、アリール基又はヘテロアリール基を表す。

[Hydrogen bonding compound of general formula (V)]

In the general formula (V), R ¹ , R ² and R ³ represent a hydrogen atom, an alkyl group, an aryl group or a heteroaryl group.

  Examples of the alkyl group include a methyl group, an ethyl group, and a propyl group. Examples of the aryl group include a phenyl group and a naphthyl group. Examples of the heteroaryl group include a pyridinyl group, a pyrimidinyl group, and a pyrazinyl group. Is mentioned.

Among them, R ¹ , R ² and R ³ preferably represent a phenyl group, and more preferably a phenyl group having a substituent at the ortho position or the meta position of the bonding position of the NH group.

  Examples of the substituent include an alkyl group, an alkoxy group, an alkoxycarbonyl group, a halogen atom, and an alkylthio group, and an alkyl group is preferable.

  Specific examples of the compound represented by the general formula (V) are given below, but the present invention is not limited to the following specific examples.

（可塑剤）
本発明の位相差フィルムは、可塑剤を有することが好ましい。好ましく添加される可塑剤としては、リン酸エステルまたはカルボン酸エステルが用いられる。リン酸エステルの例には、トリフェニルホスフェート（ＴＰＰ）およびトリクレジルホスフェート（ＴＣＰ）、クレジルジフェニルホスフェート、オクチルジフェニルホスフェート、ジフェニルビフェニルホスフェート、トリオクチルホスフェート、トリブチルホスフェートが含まれる。

(Plasticizer)
The retardation film of the present invention preferably has a plasticizer. As a plasticizer to be preferably added, phosphate ester or carboxylic acid ester is used. Examples of phosphate esters include triphenyl phosphate (TPP) and tricresyl phosphate (TCP), cresyl diphenyl phosphate, octyl diphenyl phosphate, diphenyl biphenyl phosphate, trioctyl phosphate, tributyl phosphate.

  Representative examples of the carboxylic acid ester include phthalic acid esters and citric acid esters. Examples of phthalic acid esters include dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), dioctyl phthalate (DOP), diphenyl phthalate (DPP) and diethyl hexyl phthalate (DEHP). Examples of citrate esters include triethyl O-acetyl citrate (OACTE) and tributyl O-acetyl citrate (OACTB), acetyl triethyl citrate, acetyl tributyl citrate.

  Examples of other carboxylic acid esters include butyl oleate, methylacetyl ricinoleate, dibutyl sebacate, and various trimellitic acid esters. Examples of glycolic acid esters include triacetin, tributyrin, butyl phthalyl butyl glycolate, ethyl phthalyl ethyl glycolate, methyl phthalyl ethyl glycolate, and butyl phthalyl butyl glycolate. Further trimethylolpropane tribenzoate, pentaerythritol tetrabenzoate, ditrimethylolpropane tetraacetate, ditrimethylolpropane tetrapropionate, pentaerythritol tetraacetate, sorbitol hexaacetate, sorbitol hexapropionate, sorbitol triacetate tripropionate, inositol pentaacetate Sorbitan tetrabutyrate is also preferably used.

  Among them, triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, biphenyl diphenyl phosphate, tributyl phosphate, dimethyl phthalate, diethyl phthalate, dibutyl phthalate, dioctyl phthalate, diethyl hexyl phthalate, triacetin, ethyl phthalyl ethyl glycolate, trimethylol propane Tribenzoate, pentaerythritol tetrabenzoate, ditrimethylolpropane tetraacetate, pentaerythritol tetraacetate, sorbitol hexaacetate, sorbitol hexapropionate, sorbitol triacetate tripropionate and the like are preferable. In particular, triphenyl phosphate, diethyl phthalate, ethyl phthalyl ethyl glycolate, trimethylolpropane tribenzoate, pentaerythritol tetrabenzoate, ditrimethylolpropane tetraacetate, sorbitol hexaacetate, sorbitol hexapropionate, and sorbitol triacetate tripropionate are preferable. These plasticizers may be used alone or in combination of two or more. The addition amount of the plasticizer is preferably 1 to 30% by mass, particularly 3 to 16% by mass with respect to cellulose acetate.

(Other additives)
In the present invention, deterioration inhibitors, ultraviolet absorbers, peeling accelerators, matting agents, lubricants, the aforementioned plasticizers, and the like can be appropriately used as necessary.

(Deterioration inhibitor)
In the present invention, a known deterioration (oxidation) inhibitor such as 2,6-di-tert-butyl-4-methylphenol, 4,4′-thiobis- (6-tert-butyl-3-) is added to the cellulose acetate solution. Methylphenol), 1,1′-bis (4-hydroxyphenyl) cyclohexane, 2,2′-methylenebis (4-ethyl-6-tert-butylphenol), 2,5-di-tert-butylhydroquinone, pentaerythrityl -A phenolic or hydroquinone antioxidant such as tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] can be added. Further, tris (4-methoxy-3,5-diphenyl) phosphite, tris (nonylphenyl) phosphite, tris (2,4-di-tert-butylphenyl) phosphite, bis (2,6-di-tert) Phosphorous antioxidants such as -butyl-4-methylphenyl) pentaerythritol diphosphite and bis (2,4-di-tert-butylphenyl) pentaerythritol diphosphite can be added. The addition amount of the deterioration inhibitor is preferably 0.05 to 5.0 parts by mass with respect to 100 parts by mass of the cellulose resin.

(UV absorber)
In the present invention, an ultraviolet absorber is preferably used for the dope from the viewpoint of preventing deterioration of a polarizing plate or liquid crystal. As the ultraviolet absorber, those excellent in the ability to absorb ultraviolet rays having a wavelength of 370 nm or less and having little absorption of visible light having a wavelength of 400 nm or more are preferably used from the viewpoint of good liquid crystal display properties. Specific examples of ultraviolet absorbers preferably used in the present invention include, for example, hindered phenol compounds, hydroxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, nickel complex compounds Etc. Examples of hindered phenol compounds include 2,6-di-tert-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate]. N, N′-hexamethylenebis (3,5-di-tert-butyl-4-hydroxy-hydrocinnamide), 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert) -Butyl-4-hydroxybenzyl) benzene, tris- (3,5-di-tert-butyl-4-hydroxybenzyl) -isocyanurate and the like. Examples of benzotriazole compounds include 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2,2-methylenebis (4- (1,1,3,3-tetramethylbutyl) -6 (2H-benzotriazol-2-yl) phenol), (2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-tert-butylanilino) -1,3,5- Triazine, triethylene glycol-bis [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate], N, N′-hexamethylenebis (3,5-di-tert-butyl-4- Hydroxy-hydrocinnamide), 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, 2 (2′-hydroxy-3 ′, 5′-di-tert-butylphenyl) -5-chlorobenzotriazole, (2 (2′-hydroxy-3 ′, 5′-di-tert-amylphenyl) -5 -Chlorobenzotriazole, 2,6-di-tert-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] and the like. The addition amount of these ultraviolet light inhibitors is preferably 1 ppm to 1.0%, more preferably 10 to 1000 ppm by mass in the whole retardation film.

(Matting agent)
In particular, fine particles are added to the film of the present invention from the viewpoint of improving the scratch resistance by reducing the coefficient of friction of the film surface, preventing creaking that occurs when a wide film is wound long, and preventing film breakage. It is generally done. They are called matting agents, anti-blocking agents or anti-scratching agents and have been used conventionally. They are not particularly limited as long as they have the above-described functions, and may be an inorganic compound matting agent or an organic compound matting agent.

  Specific examples of the inorganic compound matting agent include silicon-containing inorganic compounds (for example, silicon dioxide, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate, etc.), titanium oxide, and zinc oxide. , Aluminum oxide, barium oxide, zirconium oxide, strongtium oxide, antimony oxide, tin oxide, tin oxide / antimony, calcium carbonate, talc, clay, calcined kaolin, calcium phosphate, etc., more preferably silicon-containing inorganic compounds and oxides Although it is zirconium, since the turbidity of a cellulose acylate film can be reduced, silicon dioxide is particularly preferably used.

  As the silicon dioxide fine particles, for example, commercially available products having trade names such as Aerosil R972, R974, R812, 200, 300, R202, OX50, TT600 (manufactured by Nippon Aerosil Co., Ltd.) can be used. As the zirconium oxide fine particles, for example, those commercially available under trade names such as Aerosil R976 and R811 (manufactured by Nippon Aerosil Co., Ltd.) can be used.

  Preferable specific examples of the organic compound matting agent include, for example, polymers such as silicone resin, fluorine resin and acrylic resin, and among them, silicone resin is preferably used. Among the silicone resins, those having a three-dimensional network structure are particularly preferable. For example, Tospearl 103, Tospearl 105, Tospearl 108, Tospearl 120, Tospearl 145, Tospearl 3120 and Tospearl 240 (manufactured by Toshiba Silicone Co., Ltd.) A commercial product having a trade name can be used.

  As the width of the retardation film of the present invention is wider, the production efficiency can be improved. However, it is preferably 3000 mm or less from the viewpoint of preventing the occurrence of creaking and folding, and preferably 700 mm or more from the viewpoint of production efficiency. .

(Polarizer)
Since the retardation film of the present invention has high optical expression, it is preferably used as a retardation film for a polarizing plate. The polarizing plate is formed by laminating and laminating a protective film on at least one surface of the polarizer. A conventionally known polarizer can be used. For example, a hydrophilic polymer film such as a polyvinyl alcohol film is treated with a dichroic dye such as iodine and stretched. The bonding of the cellulose acylate film and the polarizer is not particularly limited, but can be performed with an adhesive made of an aqueous solution of a water-soluble polymer. The water-soluble polymer adhesive is preferably a completely saponified polyvinyl alcohol aqueous solution.

  The film of the present invention is a protective film for polarizing plate / polarizer / protective film for polarizing plate / liquid crystal cell / retardation film of the present invention / polarizer / protective film for polarizing plate, or protective film for polarizing plate / polarized light. It can preferably be used in the configuration of the optical element / retardation film of the present invention / liquid crystal cell / retardation film of the present invention / polarizer / protective film for polarizing plate. In particular, by being attached to a liquid crystal cell such as a TN type, a VA type, or an OCB type, it is possible to provide a display device that is excellent in hue variation due to a viewing angle, has high contrast, and is excellent in visibility. In particular, a polarizing plate using the protective film for a polarizing plate of the present invention has little deterioration under high temperature and high humidity conditions, and can maintain stable performance for a long time.

  The deterioration of the polarizing plate under the high temperature and high humidity condition can be evaluated by a change in the amount of light leakage before and after storage under the high temperature and high humidity condition. Here, the greater the change in the amount of light leakage, the lower the light shielding property during black display and the lower the contrast when the liquid crystal display device having this polarizing plate is stored at high temperature and high humidity.

(Liquid crystal display device)
The retardation film of the present invention and the polarizing plate using the retardation film can be used for liquid crystal cells and liquid crystal display devices in various display modes. TN (Twisted Nematic), IPS (In-Plane Switching), FLC (Ferroelectric Liquid Crystal, AFLC) Various display modes such as HAN (Hybrid Aligned Nematic) have been proposed.
The OCB mode liquid crystal cell is a liquid crystal display device using a bend alignment mode liquid crystal cell in which rod-like liquid crystalline molecules are aligned in a substantially opposite direction (symmetrically) between an upper portion and a lower portion of the liquid crystal cell. OCB mode liquid crystal cells are disclosed in US Pat. Nos. 4,583,825 and 5,410,422. Since the rod-like liquid crystal molecules are aligned symmetrically between the upper part and the lower part of the liquid crystal cell, the bend alignment mode liquid crystal cell has a self-optical compensation function. The bend alignment mode liquid crystal display device has an advantage of high response speed.

  In a VA mode liquid crystal cell, rod-like liquid crystalline molecules are aligned substantially vertically when no voltage is applied. The VA mode liquid crystal cell includes (1) a narrowly defined VA mode liquid crystal cell in which rod-like liquid crystalline molecules are aligned substantially vertically when no voltage is applied, and substantially horizontally when a voltage is applied (Japanese Patent Laid-Open No. Hei 2-). 176625) (2) Liquid crystal cell (SID97, Digest of tech. Papers (Preliminary Proceed) 28 (1997) 845 in which the VA mode is converted into a multi-domain (MVA mode) for widening the viewing angle ), (3) a liquid crystal cell of a mode (n-ASM mode) in which rod-like liquid crystalline molecules are substantially vertically aligned when no voltage is applied and twisted multi-domain alignment is applied when a voltage is applied (Sharp Technical Report No. 80, page 11); (4) A SURVAVAL mode liquid crystal cell (Monthly Display May 14th page (1999)) is included.

The VA mode liquid crystal display device includes a liquid crystal cell and two polarizing plates disposed on both sides thereof. The liquid crystal cell carries a liquid crystal between two electrode substrates. In one aspect of the transmissive liquid crystal display device of the present invention, the retardation film of the present invention is disposed between the liquid crystal cell and the polarizer of one polarizing plate, or the polarized light of both the liquid crystal cell and the polarizing plate. Two sheets are arranged between the polarizers of the plate.
When the retardation film is used only for one polarizing plate, it is particularly preferable to use it as a liquid crystal cell side protective film for a backlight side polarizing plate of a liquid crystal cell. For the lamination to the liquid crystal cell, the film of the present invention is preferably on the VA cell side. The protective film may be a normal cellulose acetate film, and is preferably thinner than the film of the present invention. For example, it is preferably 40 to 80 μm, and examples thereof include, but are not limited to, commercially available KC4UA (40 μm manufactured by Konica Minolta Opto), KC6UA (60 μm manufactured by Konica Minolta Opto), TD80 (80 μm manufactured by Fujifilm), and the like.

  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.

<Synthesis of cellulose acetate A to F>
Cellulose acetates A to F having the degree of acetyl group substitution and the weight average molecular weight shown in Table 3 were synthesized by a conventional method using cellulose obtained from wood pulp.

<Preparation of retardation film 101>
[First step]
<Fine particle dispersion 1>
Fine particles (Aerosil R812V manufactured by Nippon Aerosil Co., Ltd.) 11 parts by weight Ethanol 89 parts by weight The above was stirred and mixed with a dissolver for 50 minutes, and then dispersed with Manton Gorin.

<Fine particle addition liquid 1>
The fine particle dispersion 1 was slowly added to the dissolution tank containing methylene chloride with sufficient stirring. Further, the particles were dispersed by an attritor so that the secondary particles had a predetermined particle size. This was filtered through Finemet NF manufactured by Nippon Seisen Co., Ltd. to prepare a fine particle additive solution 1.

Methylene chloride 99 parts by mass Fine particle dispersion 1 5 parts by mass.

  A main dope having the following composition was prepared. First, methylene chloride and ethanol were added to the pressure dissolution tank. Cellulose acetate A, a partial ester compound of citric acid, compound A, compound D and fine particle additive solution 1 were added to a pressure dissolution tank containing a solvent while stirring. This is completely dissolved with heating and stirring. This was designated as Azumi Filter Paper No. The main dope was prepared by filtration using 244.

<Composition of main dope>
Methylene chloride 420 parts by weight Ethanol 36 parts by weight Cellulose acetate A 100 parts by weight Hydrogen bonding compound I-4 5.0 parts by weight Compound A (plasticizer) 3.0 parts by weight Compound D (plasticizer) 2.0 parts by weight Fine particles Additive liquid 1 1 part by mass.

(Plasticizer)
Compound A: Dioctyl phthalate Compound B: Triphenyl phosphate Compound C: Bisphenyl biphenyl phosphate Compound D: Ethyl phthalyl ethyl glycolate The above materials were put into a closed container and dissolved with stirring to prepare a dope. .

[Second step]
The temperature of each dope was set to 33 ° C., and an endless belt casting apparatus was used, and the dope was uniformly cast on a stainless steel belt support at a temperature of 33 ° C. and a width of 1500 mm. The temperature of the stainless steel belt was controlled at 30 ° C.

[Third and fourth steps]
On the stainless steel belt support, the solvent was evaporated until the amount of the residual solvent in the cast (cast) film became 75% by mass, and then peeled off from the stainless steel belt support with a peeling tension of 150 N / m. Thereafter, it was passed through a drying zone at 150 ° C.

[Fifth step]
The peeled cellulose acetate film was stretched 37% in the width direction using a tenter while applying heat at 155 ° C. immediately after passing through a drying zone at 150 ° C. The residual solvent at the start of stretching was 10%.

  From the above, since the temperature immediately before stretching was 150 ° C., the average volatilization rate was measured at 150 ° C. according to the method described in the above section (Average volatilization rate). The measured average volatilization rate is shown in Table 4.

[Sixth step]
Next, drying was terminated while the drying zone was conveyed by a number of rolls. The drying temperature was 140 ° C. and the transport tension was 100 N / m.
As described above, a retardation film 101 having a dry film thickness of 40 μm was obtained.

<Preparation of retardation films 102-122>
In the production of the retardation film 101, the retardation films 102 to 122 were similarly prepared except that the types and addition amounts of cellulose acetate, plasticizer, and hydrogen bonding compound and the temperature immediately before stretching were changed as shown in Table 4 below. Produced. The degree of acetyl group substitution and the weight average molecular weight of the cellulose acetate listed in Table 4 are shown in Table 3 above.

(Measurement of Rt immediately after finishing the sixth step and change in Rt after being placed at 23 ° C. and 55% RH for 24 hours)
The phase difference films 101 to 122 were subjected to the method described in the above section (Rt) for a period from 30 minutes to 30 minutes immediately after finishing the sixth step and after being placed at 23 ° C. and 55% RH for 24 hours. Was measured. The absolute value of the difference between Rt immediately after the end of the sixth step and 30 minutes after the completion of the sixth step and Rt after being placed at 23 ° C. and 55% RH for 24 hours is expressed as | Rt (0.5) −Rt ( 24) | is shown in Table 4.
[Measurement of Rt]
Rt (0.5) and Rt (24) of the produced retardation films 101 to 123 were measured as follows. After the sixth step (drying step), the retardation value in the thickness direction was measured within 0.5 hours to obtain Rt (0.5). Further, after the sample was stored at 23 ° C. and 55% RH for 24 hours, the retardation value in the heat direction was measured to obtain Rt (24). The retardation value in the thickness direction was measured using a KOBRA-21ADH (Oji Scientific Instruments Co., Ltd.) in an environment of 23 ° C. and 55% RH at an optical wavelength of 590 nm. The results obtained are shown in Table 4.

  The absolute value of the difference between the birefringence phase difference Rt (0.5) within 0.5 hours after production and the birefringence phase difference Rt (24) within 24 hours after production of the measured retardation films 101 to 122 is | The results are shown in Table 4 as Rt (0.5) −Rt (24) |.

表４より、アセチル基置換度が２．２〜２．５の範囲内のセルロースアセテートを有するドープにより、膜状物を形成し、延伸直前の平均揮発速度が１．５×１０^−３〜３．０×１０^−３ｇ／（ｓｅｃ・ｃｍ^２）であると、｜Ｒｔ（０．５）−Ｒｔ（２４）｜が、２ｎｍ以下となることが分かる。

From Table 4, the dope which has a cellulose acetate in the range whose acetyl group substitution degree is 2.2-2.5 forms a film-like substance, and the average volatilization rate just before extending | stretching is 1.5 * 10 < ^-3 > ^-3. It can be seen that | Rt (0.5) −Rt (24) | is 2 nm or less when it is 0.0 × 10 ⁻³ g / (sec · cm ² ).

<Preparation of hard coat film 1>
A cellulose acetate film F was prepared in the same manner as in the production of the retardation film 101 except that the main dope was changed to the following composition.

(Main dope composition)
Methylene chloride 420 parts by weight Ethanol 36 parts by weight Cellulose acetate F 100 parts by weight Compound A (plasticizer) 5.0 parts by weight Compound D (plasticizer) 5.0 parts by weight Particulate additive liquid 1 1 part by weight.

(Formation of hard coat layer)
The following hard coat layer coating composition is filtered through a polypropylene filter having a pore size of 0.4 μm to prepare a hard coat layer coating solution, which is applied to the cellulose acetate film F produced above using a micro gravure coater, and 80 ° C. in after drying, using a UV lamp, irradiance 80 mW / cm ² irradiation unit to cure the coating layer the amount of irradiation as 80 mJ / cm ^2, to form a hard coat layer 1 dry thickness 9 .mu.m, wound up A roll-shaped hard coat film 1 was produced.

(Hardcoat layer coating composition)
The following materials were stirred and mixed to obtain a hard coat layer coating composition.

Byron UR1350 (polyester urethane resin, manufactured by Toyobo Co., Ltd., solid content concentration 33% (toluene / methyl ethyl ketone: 65/35)) 6.0 parts by mass Pentaerythritol triacrylate 30 parts by mass Pentaerythritol tetraacrylate 30 parts by mass Irgacure 184 (Manufactured by BASF Japan, photopolymerization initiator) 3.0 parts by mass Irgacure 907 (manufactured by BASF, photopolymerization initiator) 1.0 part by mass Polyether-modified polydimethylsiloxane (BYK-UV3510, manufactured by Big Chemie Japan) 2.0 parts by mass Propylene glycol monomethyl ether 150 parts by mass Methyl ethyl ketone 150 parts by mass.

<Preparation of Polarizing Plate 201>
(Alkaline saponification treatment)
A polarizing plate 201 was produced by the following steps using one each of the hard coat film 1 and the retardation film 101 as a protective film for the polarizing plate.

(A) Production of Polarizer A material obtained by impregnating 10 parts by mass of glycerol and 170 parts by mass of water into 100 parts by mass of polyvinyl alcohol (hereinafter abbreviated as PVA) having a saponification degree of 99.95 mol% and a polymerization degree of 2400. After melt-kneading and defoaming, it was melt-extruded from a T-die onto a metal roll to form a film. Then, it dried and heat-processed and obtained the PVA film.

  The obtained PVA film had an average thickness of 25 μm, a moisture content of 4.4%, and a film width of 3 m. Next, the obtained PVA film was continuously processed in the order of pre-swelling, dyeing, uniaxial stretching by a wet method, fixing treatment, drying, and heat treatment to prepare a polarizer. Specifically, the PVA film was pre-swelled by immersing it in water at a temperature of 30 ° C. for 30 seconds, and swelled by immersing in an aqueous solution having an iodine concentration of 0.4 g / liter and a potassium iodide concentration of 40 g / liter for 3 minutes. Subsequently, the film was uniaxially stretched 6 times in a 50% aqueous solution with a boric acid concentration of 4% under the condition that the tension applied to the film was 700 N / m, and the potassium iodide concentration was 40 g / liter and the boric acid concentration was 40 g / liter. Then, it was immersed in an aqueous solution having a zinc chloride concentration of 10 g / liter and a temperature of 30 ° C. for 5 minutes for fixing. Thereafter, the PVA film was taken out, dried with hot air at a temperature of 40 ° C., and further heat-treated at a temperature of 100 ° C. for 5 minutes. The obtained polarizer had an average thickness of 13 μm, a polarization performance of 43.0% transmittance, a polarization degree of 99.5%, and a dichroic ratio of 40.1.

(Bonding)
According to the following processes 1-4, the polarizer, the phase difference film 101, and the hard coat film 1 were bonded together.

  Process 1: The above-mentioned polarizer was immersed in a storage tank of a polyvinyl alcohol adhesive solution having a solid content of 2% by mass for 1 to 2 seconds.

  Step 2: The retardation film 101 and the hard coat film 1 were subjected to alkali saponification treatment under the following conditions, followed by washing with water, neutralization and washing in this order, and then drying at 100 ° C. Next, the excess adhesive adhered to the polarizer immersed in the polyvinyl alcohol adhesive solution in Step 1 is gently removed, and the retardation film 101 and the hard coat film 1 are sandwiched between the polarizers as shown in FIG. Laminated.

(Alkaline saponification treatment)
Saponification step 1.5M-KOH 50 ° C. 45 seconds Water washing step Water 30 ° C. 60 seconds Neutralization step 10 parts by mass HCl 30 ° C. 45 seconds Water washing step Water 30 ° C. 60 seconds.

Step 3: The laminate was bonded at a speed of about 2 m / min at a pressure of ^{20 to} 30 N / cm ² with two rotating rollers. At this time, it was carried out with care to prevent bubbles from entering.

  Step 4: The sample produced in Step 3 was dried in a dryer at a temperature of 80 ° C. for 5 minutes to produce a polarizing plate 201.

  Step 5: A commercially available acrylic pressure-sensitive adhesive is applied to the retardation film 101 side of the polarizing plate 201 produced in Step 4 so that the thickness after drying is 25 μm, and is dried in an oven at 110 ° C. for 5 minutes for adhesion. A layer was formed, and a peelable protective film was attached to the adhesive layer. This polarized light was cut (punched) into a size of 576 × 324 mm to produce a laminate of the polarizing plate 201 and the adhesive layer. The polarizing plate 201 is used as a polarizing plate on the viewing side.

<Preparation of polarizing plates 202 to 222>
In the production of the polarizing plate 201, as shown in Table 5 below, polarizing plates 202 to 222 were produced in the same manner except that the retardation film 101 was changed to the retardation films 102 to 122. Note that the polarizing plates 202 to 222 are used as polarizing plates on the viewing side in the same manner as the polarizing plate 201.

<Preparation of Polarizing Plate 223>
In the production of the polarizing plate 201, a polarizing plate 223 was produced in the same manner except that the cellulose acetate film F was used instead of the hard coat film 1. Note that the polarizing plate 223 is used as a polarizing plate on the backlight side.

<Preparation of polarizing plates 224 to 244>
In the production of the polarizing plate 223, polarizing plates 224 to 244 were produced in the same manner except that the retardation films 102 to 122 were used as shown in Table 6 below instead of the retardation film 101. Note that the polarizing plates 224 to 244 are used as the polarizing plate on the backlight side in the same manner as the polarizing plate 223.
[Evaluation of light leakage change]
Two polarizing plates 201 to 244 were prepared, and two polarizing plates of the same type were arranged in crossed Nicols, and a transmittance (T1) of 590 nm was obtained using a spectrophotometer U3100 manufactured by Hitachi, Ltd. It was measured. Further, after both of the polarizing plates were treated at 80 ° C. and 90% for 100 hours, the transmittance (T2) when placed in crossed Nicols was measured in the same manner as described above, and the transmittance before and after the thermo treatment was measured. The change was examined, and the change in light leakage was measured according to the following equation.

Change in light leakage (%) = T2 (%)-T1 (%)
If the change in the amount of light leakage is 0 to 5%, there is no practical problem, but it is preferably 0 to 4 (%), more preferably 0 to 3 (%), and 0 to 1 (%). It is particularly preferred.
The above evaluation results are shown in Tables 5 and 6.

表５，６より、本発明の偏光板は、耐熱耐湿試験後の光漏れ量の変化が小さく、耐久性に優れていることが分かる。
＜液晶表示装置４０１の作製＞
ＳＯＮＹ製４０型ディスプレイＫＤＬ−４０Ｖ５ の液晶パネルの偏光板を剥がし、視認側の偏光板として上記作製した偏光板２０１を、ハードコート層が視認側となるようにして、粘着剤層と液晶セルの視認側ガラスとを接して貼合した。また、バックライト側には、偏光板２２３を、粘着剤と液晶セルガラスとが接するように貼合して、液晶パネル３０１を作製した。次に液晶パネル３０１を液晶テレビにセットし、液晶表示装置４０１を作製した。

From Tables 5 and 6, it can be seen that the polarizing plate of the present invention has a small change in light leakage after the heat and humidity resistance test and is excellent in durability.
<Production of Liquid Crystal Display Device 401>
The polarizing plate of the liquid crystal panel of Sony 40-type display KDL-40V5 is peeled off, and the prepared polarizing plate 201 is used as the polarizing plate on the viewing side so that the hard coat layer is on the viewing side, and the adhesive layer and the liquid crystal cell It was bonded in contact with the viewing side glass. In addition, a polarizing plate 223 was bonded to the backlight side so that the pressure-sensitive adhesive and the liquid crystal cell glass were in contact with each other, so that a liquid crystal panel 301 was manufactured. Next, the liquid crystal panel 301 was set on a liquid crystal television, and a liquid crystal display device 401 was manufactured.

<Production of Liquid Crystal Display Devices 402 to 422>
In the production of the liquid crystal display device 401, as shown in Table 7, the liquid crystal display device 402 was similarly changed except that the viewing side polarizing plate 201 was changed to 202 to 222 and the backlight side polarizing plate 223 was changed to 224 to 244, respectively. -422 were made.

<Evaluation>
[Hue fluctuation]
About each produced said liquid crystal display device 401-422, the hue fluctuation | variation was measured using the measuring machine (EZ-Contrast160D, ELDIM company make). In the CIE 1976 and UCS coordinates, the hue is measured at intervals of an angle of 2 ° in the vertical direction (up to 80 ° to down 80 ° from the display normal line), and is the maximum between the measured angles within the hue fluctuation range shown in the following formula. The hue fluctuation range is referred to as hue fluctuation and is shown in Table 7.

Hue fluctuation range = [(Δu ^* ) ² + (Δv ^* ) ² ] ^1/2
(Where Δu ^* is the difference in u ^* between the two angles measured, and Δv ^* is the difference in v ^* between the two angles measured.)
[Front contrast]
The measurement was performed after the backlight of each liquid crystal display device was lit continuously for one week in an environment of 23 ° C. and 55% RH. For measurement, EZ-Contrast 160D manufactured by ELDIM was used to measure the luminance from the normal direction of the display screen of white display and black display with a liquid crystal display device, and the ratio was defined as the front contrast.

Front contrast = (brightness of white display measured from normal direction of display device) / (brightness of black display measured from normal direction of display device)
The front contrast is shown in Table 7.

表７より、本発明の液晶表示装置は、色相変動が小さく、正面コントラストが高いことが分かる。

From Table 7, it can be seen that the liquid crystal display device of the present invention has a small hue variation and a high front contrast.

DESCRIPTION OF SYMBOLS 1 Base film 2 Hard coat layer 3 Polarizer 4 Phase difference film 5 Adhesion layer 6 Hard coat film 7 Polarizing plate

Claims (2)

A method for producing a retardation film having the following first to sixth steps ,
In the first step, cellulose acetate having an average degree of acetyl group substitution in the range of 2.2 to 2.5 in an organic solvent containing 90% by mass or more of a halogen-based organic solvent, a plasticizer, and the following general formula ( A step of preparing a dope by dissolving the hydrogen bonding compound represented by any one of I) to (IV) ,
The second step is a step of casting the dope on a metal support ,
Third step is a step of forming a film-like product drying the dope was cast,
Fourth step is a step of peeling off the film-like material from the metal support,
Fifth step is a step of stretching said film-like material was peeled,
Sixth step is a step of volatilizing the organic solvent in the film-like material was dried stretched the film-like material,
And,
Immediately before the said film-like material is stretched, in the range of the film-like material × 1.5 The average volatilization rate of the organic solvent ^{10 -3 ~3.0 × 10 -3 g /} (sec · cm 2) Control and further
The film-like material from which the organic solvent has been volatilized in the sixth step is measured at a light wavelength of 590 nm in an environment of 23 ° C. and 55% RH within 0.5 hours immediately after the completion of the sixth step. Retardation value Rt (0.5) in the thickness direction, and after standing for 24 hours in a 23 ° C./55% RH environment immediately after finishing the sixth step, in a 23 ° C./55% RH environment The absolute value | Rt (0.5) −Rt (24) | of the difference from the retardation value Rt (24) in the thickness direction measured at an optical wavelength of 590 nm is controlled to be 2 nm or less. A method for producing a retardation film.

[In General Formula (I), R ¹¹ and R ^{11 ′} each independently represents an alkyl group. R ¹² and R ^{12 ′} each independently represent a hydrogen atom or a group that can be substituted on a benzene ring.
X ¹¹ and X ^{11 ′} each independently represent a hydrogen atom or a group capable of substituting for a benzene ring. R ¹¹ and X ¹¹ , R ^{11 ′} and X ^{11 ′} , R ¹² and X ¹¹ , and R ^{12 ′} and X ^{11 ′} may be bonded to each other to form a ring. L represents —S— or —CHR ¹³ —, and R ¹³ represents a hydrogen atom or an alkyl group. ]

[In General Formula (II) , each of R ^{11 to} R ³⁵ independently represents a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an amino group, an alkoxy group, an aryloxy group, an acyl group, or an alkoxycarbonyl group. Group, aryloxycarbonyl group, acyloxy group, acylamino group, alkoxycarbonylamino group, aryloxycarbonylamino group, sulfonylamino group, sulfamoyl group, carbamoyl group, alkylthio group, arylthio group, sulfonyl group, sulfinyl group, ureido group, phosphorus Represents acid amide group, hydroxy group, mercapto group, halogen atom, cyano group, sulfo group, carboxy group, nitro group, hydroxamic acid group, sulfino group, hydrazino group, imino group, heterocyclic group, silyl group, these groups Is unsubstituted It may have a substituent, two of any of R ¹¹ to R ³⁵ may be bonded to each other to form a ring. X represents a hydroxy group. ]

[In General Formula (III), A, B, and C represent an aromatic ring or an aromatic heterocyclic ring, and L ¹ , L ^2, and L ³ are divalent groups selected from —NH—, —NHCO—, and —CONH—. X ¹ and X ² represent a carbon atom or a nitrogen atom, and R ¹ represents a substituent. ]

[In General Formula (IV), A represents an aromatic ring or a cyclohexyl ring, R ¹ represents a hydrogen atom or an alkyl group, and R ² represents a hydrogen atom, an alkyl group or an alkoxy group, and n represents 2 to 4. Represent. ] The method for producing a retardation film according to claim 1, wherein the hydrogen bonding compound is contained within a range of 1 to 10% by mass.

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