JP2009139812A - Roll-shaped retardation film, method for manufacturing the roll-shaped retardation film, and circularly polarizing plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a retardation film having superior black tone. <P>SOLUTION: The retardation film is such that a slow phase axis makes an angle of 45±5°, with respect to the longitudinal direction; and in the measurement of detecting the intensity of scattered light, at a 130° position from the light source, which is a measurement of the scattered light intensity of the film, at an incident angle of 90° in a scattered light profile by a goniophotometer, the difference in the scattered light intensity between a test, in which the slow phase axis of the film is placed horizontal with respect to a sample stand and a test, in which the slow phase axis is perpendicular to the sample stand, is not larger than 0.05. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a retardation film used for an organic EL device, and relates to a roll-like retardation film having high transparency and high productivity, a method for producing a roll-like retardation film, and a circularly polarizing plate.

  In recent years, the development and commercialization of technology for increasing the size and thickness of display devices have been actively promoted.

  Typical display devices include liquid crystal televisions, plasma televisions, organic EL televisions, etc. Among them, organic EL elements are particularly excellent in terms of luminous efficiency, low voltage driving, light weight, and low cost, and are extremely attention. It is an element that is exposed to.

  The organic EL element injects electrons from the cathode, injects holes from the anode, and recombines them in the light emitting layer, thereby generating visible light emission corresponding to the light emitting characteristics of the light emitting layer. A transparent conductive material is used for the anode, and a metal electrode is usually used for the cathode.

  In other words, the organic EL display has a structure in which the cathode is a metal mirror surface having a strong light reflectivity, so that the reflection of external light is noticeable and the blackness is deteriorated when light is not emitted.

  In order to prevent external light reflection, a circularly polarizing plate in which a retardation film called a λ / 4 plate (or λ / 2) and a linear polarizing plate are laminated has been used.

  The transparency of the retardation film correlates with this blackness, and a polycarbonate resin or a norbornene resin having a relatively low haze is preferably used (Patent Document 1).

  However, since these resins have insufficient wavelength dispersion, a plurality of retardation films are used for the adjustment, and as a result, the haze cannot be lowered enough to obtain a satisfactory blackness. .

  Originally, the use of circularly polarizing plates has also caused the deterioration of visibility from the diagonal direction of the display. is needed.

  In order to improve the visibility from the diagonal, there was an examination from the alignment liquid crystal layer coated on the retardation film, but the film as the base material was not satisfactory, so the problem was solved. It is not right (Patent Document 2).

  On the other hand, in making the circularly polarizing plate, conventionally, after forming a transparent resin film, it is stretched in the longitudinal direction or the lateral direction of the film to optically appear a slow axis in the film plane. Then, after cutting out only a necessary area, the slow axis and the transmission axis of the linearly polarizing plate are arranged so that they are obliquely around 45 °, and the method is bonded to the linearly polarizing plate.

  This method is caused by the problem that the productivity cannot be increased due to loss at the time of cutting out the retardation film or the labor of cutting out itself, and the variation in the bonding axis adjustment between each retardation film and the linear polarizing plate. There was a problem that performance fluctuations are likely to occur.

In order to solve this problem, the oblique stretching method (Patent Document 3) and the application of the alignment liquid crystal layer of Patent Document 2 have been tried. However, these techniques alone have improved the productivity, but the image quality is improved. The blackness of can not be improved sufficiently.
JP 2007-94007 A JP 2006-243653 A JP 2005-284024 A

  The objective of this invention is providing the polarizing plate using this retardation film, the manufacturing method of the retardation film excellent in the expression of blackness, the highly productive retardation film in an organic electroluminescent display.

The above object of the present invention is achieved by the following configurations.
(1) Measurement of scattered light intensity of a film having a slow axis of 45 ± 5 ° with respect to the longitudinal direction and an incident light of 90 ° of the scattered light profile of the goniophotometer, at a position of 130 ° from the light source In the measurement to detect the scattered light intensity in the film, the difference in scattered light intensity between the case where the film slow axis is installed horizontally on the sample stage and the case where the film slow axis is installed vertically is 0.05 or less. Roll retardation film.
(2) The retardation film is an acrylic polymer and an ester compound in which at least one of a pyranose structure or a furanose structure is 1 to 12, and all or part of the OH groups of the structure are esterified. A roll-like retardation film as described in (1) above, which is a cellulose ester film containing at least one kind.
(3) A circularly polarizing plate having a polarizer and the retardation film according to (1) or (2).
(4) The method for producing a roll-like retardation film as described in (1) or (2) above, comprising a step of stretching in a slanting direction with respect to the longitudinal direction or regulating shrinkage. A method for producing a roll-like retardation film.

  According to the present invention, in an organic EL display, a retardation film excellent in expression of blackness, a production method of a retardation film with high productivity, and a polarizing plate using the retardation film can be provided.

  Hereinafter, the best mode for carrying out the present invention will be described in detail.

  In the roll-like retardation film of the present invention, the slow axis is in the film plane, and θ1 is 45 ° ± 5 °, preferably 45 ° ± 3, where θ1 is an angle with the longitudinal direction. °.

  In the roll-like retardation film of the present invention, the longitudinal direction coincides with the film forming direction.

  In general, the retardation film of the present invention preferably has an in-plane retardation Ro of 20 to 200 nm and a thickness direction retardation Rt of 70 to 400 nm. In addition, the cellulose ester film which is the retardation film of the present invention is also preferably in this range.

When used as a circularly polarizing plate, it preferably has a retardation that simultaneously satisfies the following formulas (1) to (3).
(1) 130 ≦ Ro ≦ 160
(2) −30 ≦ Rt ≦ 30
(3) 0.78 ≦ Ro (480) / Ro (650) ≦ 0.96
Ro = (nx−ny) × d
Rt = ((nx + ny) / 2−nz) × d
(Where nx is the refractive index in the slow axis direction in the plane of the retardation film, ny is the refractive index in the direction perpendicular to the slow axis in the plane, nz is the refractive index in the thickness direction, and d is the refractive index in the thickness direction) Represents the thickness (nm) of the retardation film, the refractive index is measured at 590 nm, and Ro (480) and Ro (650) represent Ro when measured at wavelengths of 480 nm and 650 nm, respectively.
The refractive index can be obtained at a wavelength of 590 nm under an environment of 23 ° C. and 55% RH using, for example, KOBRA-21ADH (Oji Scientific Instruments).
<Scattered light measured by goniophotometer>
The retardation film of the present invention is characterized in that the scattered light measured by a goniophotometer is in a certain range even if it is stretched to obtain the retardation.

  In order to improve the blackness, it has been said that it is necessary to reduce the haze of the cellulose ester film, but by simply reducing the haze corresponding to the straight light, the blackness is not necessarily set to a desired value. I know that I can't.

  In contrast, the present inventors have found that it is necessary to eliminate anisotropic scattering. Anisotropic scattering refers to the difference in scattered light intensity between the slow axis direction of the film and the direction orthogonal thereto. This anisotropic scattering is measured with a goniophotometer.

<Anisotropic scattering measurement device>
FIG. 1 shows an outline of a goniophotometer (model: GP-1-3D, manufactured by Optec Corporation). G1. Light source lamp, G2. Spectrometer, G3. Sample stage (also called stage), G4. Sample (not shown), G5. It is a light receiving part.

  The light source uses a 12V50W halogen bulb, and the light receiving section uses a photomultiplier tube (Photomaru Hamamatsu Photonics R636-10).

  (A) shows the arrangement of a light source lamp, a spectroscope, a sample stage (stage), and an integrating sphere for measuring light intensity at the time of reference measurement for measuring reference light or transmittance measurement.

  (B) shows the arrangement of the light source lamp, the spectroscope, the sample stage, and the integrating sphere when the measurement sample is placed on the sample stage and the reflectance is measured.

  The sample stage is usually a measurement sample vertical hanging type, and the measurement sample is fixed with a clamp, and the lower part of the stage is an angle indexing rotary table. The transmittance is changed by changing the angle between the sample surface and the incident surface. It is a structure that can measure the reflectance.

  The anisotropic scattered light intensity according to the present invention can be measured by the arrangement (a). That is, the measurement of the scattered light intensity of a film having an incident light of 90 ° in the scattered light profile of the goniophotometer refers to the scattered light intensity when light is applied perpendicularly to the sample from the light source of the goniophotometer.

  When measuring the scattered light intensity at a position of 130 ° from the light source, the direction connecting the normal direction of the light source, the observation point of the sample, and the integrating sphere shown in FIG. This is the scattered light intensity measured when the angle θ formed by is 130 °.

  In the present invention, in the measurement of scattered light intensity at a position where θ is 130 °, the difference in scattered light intensity between the case where the film slow axis is horizontally installed on the sample stage and the case where the film is vertically installed is 0.05 or less. It is characterized by being.

  A normal spirit level can be used to achieve horizontal and vertical conditions.

  Various angles can be selected as θ, but in the present invention, it is set to 130 °, which has the highest correlation with blackness, which is the final evaluation as a liquid crystal display device.

  When horizontal, the scattered light intensity when vertical is 0.01 to 0.25, preferably 0.20 or less, and more preferably 0.10 or less.

  The smaller the scattered light intensity difference, the better.

  In order to achieve the scattered light intensity of the present invention, the retardation film of the present invention has at least one of an acrylic polymer and at least one of a pyranose structure or a furanose structure and no more than 12 OH groups of the structure. It is preferable that the cellulose ester film contains at least one ester compound obtained by esterifying all or part of the above.

<Cellulose ester>
The cellulose ester of the present invention is not particularly limited, but the cellulose ester is a carboxylic acid ester having about 2 to 22 carbon atoms, and may be an aromatic carboxylic acid ester, particularly a lower fatty acid ester having 6 or less carbon atoms. It is preferable.

  The acyl group bonded to the hydroxyl group may be linear or branched or may form a ring. Furthermore, another substituent may be substituted. When the degree of substitution is the same, birefringence decreases when the number of carbon atoms is large, and therefore, the number of carbon atoms is preferably selected from acyl groups having 2 to 6 carbon atoms. The cellulose ester preferably has 2 to 4 carbon atoms, more preferably 2 to 3 carbon atoms.

  Specifically, the cellulose ester includes cellulose acetate propionate, cellulose acetate butyrate, or a mixed fatty acid ester of cellulose to which a propionate group or a butyrate group is bonded in addition to an acetyl group such as cellulose acetate propionate butyrate. Can be used.

  The butyryl group forming butyrate may be linear or branched. As the cellulose ester preferably used in the present invention, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, and cellulose acetate phthalate are particularly preferably used.

  Preferred cellulose esters other than cellulose acetate phthalate for the present invention preferably satisfy the following formulas (1) and (2).

Formula (1) 2.0 <= X + Y <= 3.0
Formula (2) 0 ≦ Y ≦ 1.5
In the formula, X is the degree of substitution of the acetyl group, and Y is the degree of substitution of the propionyl group or butyryl group, or a mixture thereof.

  Further, in order to obtain optical characteristics that meet the purpose, resins having different degrees of substitution may be mixed and used. The mixing ratio is preferably 10:90 to 90:10 (mass ratio).

  Of these, cellulose acetate propionate is particularly preferably used. In cellulose acetate propionate, 1.0 ≦ X ≦ 2.5, preferably 0.1 ≦ Y ≦ 1.5, and 2.0 ≦ X + Y ≦ 3.0. The measuring method of the substitution degree of an acyl group can be measured according to ASTM-D817-96.

  The number average molecular weight of the cellulose ester used in the present invention is preferably in the range of 60,000 to 300,000 because the mechanical strength of the resulting film is strong. Furthermore, the thing of 70000-200000 is used preferably.

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

  The measurement conditions are as follows.

Solvent: Methylene chloride Column: Shodex K806, K805, K803G (Used by connecting three Showa Denko Co., Ltd.)
Column temperature: 25 ° C
Sample concentration: 0.1% by mass
Detector: RI Model 504 (manufactured by GL Sciences)
Pump: L6000 (manufactured by Hitachi, Ltd.)
Flow rate: 1.0ml / min
Calibration curve: Standard polystyrene STK standard polystyrene (manufactured by Tosoh Corporation) Mw = 100000 to 500 calibration curves with 13 samples were used. Thirteen samples are used at approximately equal intervals.

  The cellulose used as a raw material of the cellulose ester used in the present invention is not particularly limited, and examples thereof include cotton linter, wood pulp, and kenaf. Moreover, the cellulose ester obtained from them can be mixed and used in arbitrary ratios, respectively.

  The cellulose ester such as cellulose acetate phthalate of the present invention can be produced by a known method. Specifically, it can be synthesized with reference to the method described in JP-A-10-45804.

<Acrylic polymer>
In the present invention, an acrylic polymer is added to the cellulose ester film. Here, the acrylic polymer includes a methacrylic polymer.

  As an acrylic polymer used in the present invention, when it is contained in a cellulose ester film, it preferably exhibits negative birefringence as a function of the stretching direction, and the structure is not particularly limited. A polymer having a weight average molecular weight of 500 to 30,000 obtained by polymerizing an ethylenically unsaturated monomer is preferred.

(Test method for birefringence of acrylic polymer)
The acrylic polymer was dissolved in a solvent to form a cast film, and then dried by heating. The film having a transmittance of 80% or more was evaluated for birefringence.

  Refractive index measurement was performed using an Abbe refractometer-4T (manufactured by Atago Co., Ltd.) using a multiwavelength light source. The refractive index ny in the stretching direction and the refractive index in the in-plane direction perpendicular to each other were defined as nx. For films with (ny−nx) <0 for each refractive index at 550 nm, the acrylic polymer is judged to be negatively birefringent with respect to the stretch direction.

  The acrylic polymer having a weight average molecular weight of 500 or more and 30000 or less used in the present invention may be an acrylic polymer having an aromatic ring in the side chain or an acrylic polymer having a cyclohexyl group in the side chain.

  When the weight average molecular weight of the polymer is 500 or more and 30000 or less and the composition of the polymer is controlled, for example, when the cellulose ester film is a particularly preferable cellulose ester film in the present invention, the cellulose ester and the polymer The compatibility with can be improved.

  As for the acrylic polymer having an aromatic ring in the side chain or the acrylic polymer having a cyclohexyl group in the side chain, if the weight average molecular weight is 500 or more and 10,000 or less, in addition to the above, cellulose after film formation The transparency of the ester film is excellent, the moisture permeability is extremely low, and it exhibits excellent performance as a protective film for polarizing plates.

  Since the polymer has a weight average molecular weight of 500 or more and 30000 or less, it is considered to be between the oligomer and the low molecular weight polymer. In order to synthesize such a polymer, it is difficult to control the molecular weight in normal polymerization, and it is desirable to use a method that can align the molecular weight as much as possible by a method that does not increase the molecular weight too much.

  In particular, the acrylic polymer used in the cellulose ester film of the present invention includes an ethylenically unsaturated monomer Xa having no aromatic ring and a hydroxyl group in the molecule, and an ethylene having a hydroxyl group and no aromatic ring in the molecule. Polymer X having a weight average molecular weight of 2,000 to 30,000 obtained by copolymerization of a polymerizable unsaturated monomer Xb and a copolymerizable ethylenically unsaturated monomer excluding Xa and Xb, or ethylene having no aromatic ring The polymer Y is preferably a polymer Y having a weight average molecular weight of 500 or more and 3000 or less, obtained by polymerizing the polymerizable unsaturated monomer Ya and an ethylenically unsaturated monomer copolymerizable with Ya.

[Polymer X, Polymer Y]
The method for adjusting Ro and Rt of the cellulose ester film according to the present invention includes ethylenically unsaturated monomer Xa having no aromatic ring and hydroxyl group in the molecule, and ethylene having a hydroxyl group and no aromatic ring in the molecule. High molecular weight polymer X having a weight average molecular weight of 2,000 to 30,000 obtained by copolymerization of the polymerizable unsaturated monomer Xb and a copolymerizable ethylenically unsaturated monomer excluding Xa and Xb, and more preferably, Contains a low molecular weight polymer Y having a weight average molecular weight of 500 to 3,000 obtained by polymerizing an ethylenically unsaturated monomer Ya having no aromatic ring and an ethylenically unsaturated monomer copolymerizable with Ya It is preferable.

  The polymer X used in the present invention includes an ethylenically unsaturated monomer Xa having no aromatic ring and a hydroxyl group in the molecule and an ethylenically unsaturated monomer Xb having no hydroxyl ring in the molecule and having a hydroxyl group, Xa and Xb. Is a polymer having a weight average molecular weight of 2000 or more and 30000 or less obtained by copolymerization with a copolymerizable ethylenically unsaturated monomer other than.

  Preferably, Xa is an acrylic or methacrylic monomer having no aromatic ring and hydroxyl group in the molecule, and Xb is an acrylic or methacrylic monomer having no aromatic ring and having a hydroxyl group in the molecule.

  The polymer X used in the present invention is represented by the following general formula (X).

Formula (X)
− [Xa] _m − [Xb] _n − [Xc] _p −
In the general formula (X), Xa represents an ethylenically unsaturated monomer having no aromatic ring and hydroxyl group in the molecule, and Xb represents an ethylenically unsaturated monomer having no aromatic ring and having a hydroxyl group in the molecule. Xc represents a copolymerizable ethylenically unsaturated monomer excluding Xa and Xb. m, n, and p each represent a molar composition ratio. However, m ≠ 0 and m + n + p = 100.

  Furthermore, the polymer X is preferably a polymer represented by the following general formula (X-1).

Formula (X-1)
_{- [CH 2 -C (-R 1} ) (- CO 2 R 2)] m - [CH 2 -C (-R 3) (- CO 2 R 4 -OH) -] n - [Xc] p -
In the general formula (X-1), R ₁ and R ₃ each represent a hydrogen atom or a methyl group. R ₂ represents an alkyl group having 1 to 12 carbon atoms or a cycloalkyl group. R4 is _{-CH 2 -, - C 2 H} 4 - or -C ₃ H ₆ - represents a. Xc represents a monomer unit that can be polymerized to [CH ₂ —C (—R ₁ ) (— CO ₂ R ₂ )] or [CH ₂ —C (—R ₃ ) (— CO ₂ R ₄ —OH) —]. To express. m, n, and p represent a molar composition ratio. However, m ≠ 0 and m + n + p = 100.

  Although the monomer as a monomer unit which comprises the polymer X which concerns on this invention is mentioned below, it is not limited to this.

  In X, the hydroxyl group means not only a hydroxyl group but also a group having an ethylene oxide chain.

  Examples of the ethylenically unsaturated monomer Xa having no aromatic ring and hydroxyl group in the molecule include methyl acrylate, ethyl acrylate, propyl acrylate (i-, n-), and butyl acrylate (n-, i-, s). -, T-), pentyl acrylate (n-, i-, s-), hexyl acrylate (n-, i-), heptyl acrylate (n-, i-), octyl acrylate (n-, i -), Nonyl acrylate (n-, i-), myristyl acrylate (n-, i-), acrylic acid (2-ethylhexyl), acrylic acid (ε-caprolactone), etc. The thing changed into acid ester can be mentioned.

  Among these, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, and propyl methacrylate (i-, n-) are preferable.

  The ethylenically unsaturated monomer Xb having no hydroxyl ring in the molecule and having a hydroxyl group is preferably acrylic acid or methacrylic acid ester as a monomer unit having a hydroxyl group, such as acrylic acid (2-hydroxyethyl), acrylic acid. (2-hydroxypropyl), acrylic acid (3-hydroxypropyl), acrylic acid (4-hydroxybutyl), acrylic acid (2-hydroxybutyl), or those obtained by replacing these acrylic acids with methacrylic acid. Preferred are acrylic acid (2-hydroxyethyl) and methacrylic acid (2-hydroxyethyl), acrylic acid (2-hydroxypropyl), and acrylic acid (3-hydroxypropyl).

  Xc is not particularly limited as long as it is a monomer other than Xa and Xb and is a copolymerizable ethylenically unsaturated monomer, but preferably has no aromatic ring.

  The molar composition ratio m: n of Xa and Xb is preferably in the range of 99: 1 to 65:35, more preferably in the range of 95: 5 to 75:25. P of Xc is 0-10. Xc may be a plurality of monomer units.

  When the molar composition ratio of Xa is large, the compatibility with the cellulose ester is improved, but the retardation value Rt in the film thickness direction is increased. When the molar composition ratio of Xb is large, the compatibility is deteriorated, but the effect of reducing Rt is high.

  Further, if the molar composition ratio of Xb exceeds the above range, haze tends to occur during film formation, and it is preferable to optimize these and determine the molar composition ratio of Xa and Xb.

  The molecular weight of the high molecular weight polymer X is more preferably 5,000 or more and 30,000 or less, and still more preferably 8,000 or more and 25,000 or less.

  By setting the weight average molecular weight to 5000 or more, advantages such as little dimensional change under high temperature and high humidity of the cellulose ester film can be obtained.

  When the weight average molecular weight is 30000 or less, compatibility with the cellulose ester is further improved, and bleeding out under high temperature and high humidity and further haze generation immediately after film formation are suppressed.

  The weight average molecular weight of the polymer X according to the present invention can be adjusted by a known molecular weight adjusting method. Examples of such a molecular weight adjusting method include a method of adding a chain transfer agent such as carbon tetrachloride, lauryl mercaptan, octyl thioglycolate, and the like.

  The polymerization temperature is usually from room temperature to 130 ° C., preferably from 50 ° C. to 100 ° C., and this temperature or the polymerization reaction time can be adjusted.

  In addition, a weight average molecular weight etc. can be calculated | required according to the above-mentioned method.

  The low molecular weight polymer Y used in the present invention is a polymer having a weight average molecular weight of 500 or more and 3000 or less obtained by polymerizing an ethylenically unsaturated monomer Ya having no aromatic ring. A weight average molecular weight of 500 or more is preferred because the residual monomer in the polymer is reduced.

  Moreover, it is preferable to set it as 3000 or less in order to maintain retardation value Rt fall performance. Ya is preferably an acrylic or methacrylic monomer having no aromatic ring.

  The polymer Y used in the present invention is represented by the following general formula (Y).

General formula (Y)
− [Ya] _k − [Yb] _q −
In the general formula (Y), Ya represents an ethylenically unsaturated monomer having no aromatic ring, and Yb represents an ethylenically unsaturated monomer copolymerizable with Ya. k and q each represent a molar composition ratio. However, k ≠ 0 and k + q = 100.

  The polymer Y according to the present invention is more preferably a polymer represented by the following general formula (Y-1).

General formula (Y-1)
_{- [CH 2 -C (-R 5} ) (- CO 2 R 6)] k - [Yb] q -
In the general formula (Y-1), R ₅ represents a hydrogen atom or a methyl group, respectively. R ₆ represents an alkyl group having 1 to 12 carbon atoms or a cycloalkyl group. Yb represents a monomer unit copolymerizable with [CH ₂ —C (—R ₅ ) (— CO ₂ R ₆ )]. k and q each represent a molar composition ratio. However, k ≠ 0 and k + q = 100.

Yb is not particularly limited as long as it is an ethylenically unsaturated monomer copolymerizable with [CH ₂ —C (—R ₅ ) (— CO ₂ R ₆ )] which is Ya. Yb may be plural. k + q = 100, q is preferably 0-30.

  The ethylenically unsaturated monomer Ya constituting the polymer Y obtained by polymerizing the ethylenically unsaturated monomer having no aromatic ring is, for example, methyl acrylate, ethyl acrylate, propyl acrylate ( i-, n-), butyl acrylate (n-, i-, s-, t-), pentyl acrylate (n-, i-, s-), hexyl acrylate (n-, i-), acrylic Acid heptyl (n-, i-), octyl acrylate (n-, i-), nonyl acrylate (n-, i-), myristyl acrylate (n-, i-), cyclohexyl acrylate, acrylic acid ( 2-ethylhexyl), acrylic acid (ε-caprolactone), acrylic acid (2-hydroxyethyl), acrylic acid (2-hydroxypropyl), acrylic acid (3-hydroxypropiyl) ), Acrylic acid (4-hydroxybutyl), acrylic acid (2-hydroxybutyl), methacrylic acid ester, the above acrylic acid ester changed to methacrylic acid ester; unsaturated acid, for example, acrylic acid, methacrylic acid And maleic anhydride, crotonic acid, itaconic acid and the like.

  Yb is not particularly limited as long as it is an ethylenically unsaturated monomer copolymerizable with Ya. Examples of vinyl esters include vinyl acetate, vinyl propionate, vinyl butyrate, vinyl valerate, vinyl pivalate, and vinyl caproate. Vinyl caprate, vinyl laurate, vinyl myristate, vinyl palmitate, vinyl stearate, vinyl cyclohexanecarboxylate, vinyl octylate, vinyl methacrylate, vinyl crotonate, vinyl sorbate, vinyl cinnamate and the like are preferred. Yb may be plural.

  In order to synthesize the polymers X and Y, it is difficult to control the molecular weight in normal polymerization, and it is desirable to use a method that can make the molecular weights as uniform as possible without increasing the molecular weight.

  Such polymerization methods include a method using a peroxide polymerization initiator such as cumene peroxide and t-butyl hydroperoxide, a method using a polymerization initiator in a larger amount than normal polymerization, and a mercapto compound in addition to the polymerization initiator. And a method of using a chain transfer agent such as carbon tetrachloride, a method of using a polymerization terminator such as benzoquinone and dinitrobenzene in addition to the polymerization initiator, and further, Japanese Patent Application Laid-Open No. 2000-128911 or 2000-344823. Examples thereof include a compound having one thiol group and a secondary hydroxyl group, or a bulk polymerization method using a polymerization catalyst in which the compound and an organometallic compound are used in combination. Used.

  In particular, the polymer Y is preferably a polymerization method using a compound having a thiol group and a secondary hydroxyl group in the molecule as a chain transfer agent. In this case, the terminal of the polymer Y has a hydroxyl group and a thioether resulting from the polymerization catalyst and the chain transfer agent. The compatibility of Y and cellulose ester can be adjusted by this terminal residue.

  The hydroxyl values of the polymers X and Y are preferably 30 to 150 [mg KOH / g].

  The hydroxyl value is measured in accordance with JIS K 0070 (1992). This hydroxyl value is defined as the number of mg of potassium hydroxide required to neutralize acetic acid bonded to a hydroxyl group when 1 g of a sample is acetylated.

  Specifically, sample Xg (about 1 g) is precisely weighed in a flask, and 20 ml of an acetylating reagent (a solution obtained by adding pyridine to 20 ml of acetic anhydride to 400 ml) is accurately added thereto. An air cooling tube is attached to the mouth of the flask and heated in a glycerin bath at 95-100 ° C.

  After 1 hour and 30 minutes, the mixture is cooled, 1 ml of purified water is added from an air condenser, and acetic anhydride is decomposed into acetic acid.

  Next, titration is performed with a 0.5 mol / L potassium hydroxide ethanol solution using a potentiometric titrator, and the inflection point of the obtained titration curve is set as the end point.

  Further, as a blank test, titration is performed without a sample, and an inflection point of the titration curve is obtained. The hydroxyl value is calculated by the following formula.

Hydroxyl value = {(BC) × f × 28.05 / X} + D
In the formula, B is the amount (ml) of 0.5 mol / L potassium hydroxide ethanol solution used for the blank test, C is the amount (ml) of 0.5 mol / L potassium hydroxide ethanol solution used for titration, f is a factor of a 0.5 mol / L potassium hydroxide ethanol solution, D is an acid value, and 28.05 is 1/2 of 1 mol amount 56.11 of potassium hydroxide.

  The above-mentioned polymer X and polymer Y are both excellent in compatibility with cellulose ester, excellent in productivity without evaporation and volatilization, good retention as a protective film for polarizing plates, low moisture permeability, and dimension stability. Excellent in properties.

The content of the polymer X and the polymer Y in the cellulose ester film is preferably in a range satisfying the following formulas (i) and (ii). When the content of the polymer X is Xg (mass% = (mass of polymer X / mass of cellulose ester) × 100) and the content of the polymer Y is Yg (mass%),
Formula (i) 5 ≦ Xg + Yg ≦ 35 (mass%)
Formula (ii) 0.05 ≦ Yg / (Xg + Yg) ≦ 0.4
A preferable range of (Xg + Yg) in the formula (i) is 10 to 35% by mass. If the polymer X and the polymer Y are 5 mass% or more as a total amount with respect to the total mass of the cellulose ester, the polymer X and the polymer Y have a sufficient effect for adjusting the retardation value Rt.

  The polymer X and the polymer Y can be directly added and dissolved as a material constituting the dope solution described later, or can be added to the dope solution after being previously dissolved in an organic solvent for dissolving the cellulose ester.

<Ester compound in which at least one of pyranose structure or furanose structure is 1 or more and 12 or less and all or part of OH groups of the structure are esterified>
The cellulose ester film of the present invention is characterized by comprising an ester compound having at least one pyranose structure or at least one furanose structure and having all or part of OH groups in the structure esterified.

  The proportion of esterification is preferably 70% or more of the OH groups present in the pyranose structure or furanose structure.

  In the present invention, ester compounds are collectively referred to as sugar ester compounds.

  Examples of the ester compound of the present invention include the following, but the present invention is not limited thereto.

  Glucose, galactose, mannose, fructose, xylose or arabinose, lactose, sucrose, nystose, 1F-fructosyl nystose, stachyose, maltitol, lactitol, lactulose, cellobiose, maltose, cellotriose, maltotriose, raffinose or kestose .

  In addition, gentiobiose, gentiotriose, gentiotetraose, xylotriose, galactosyl sucrose, and the like are also included.

  Among these compounds, compounds having both a pyranose structure and a furanose structure are particularly preferable.

  Examples include sucrose, kestose, nystose, 1F-fructosyl nystose, stachyose, and more preferably sucrose.

  The monocarboxylic acid used for esterifying all or part of the OH groups in the pyranose structure or furanose structure of the present invention is not particularly limited, and known aliphatic monocarboxylic acids, alicyclic monocarboxylic acids, An aromatic monocarboxylic acid or the like can be used. The carboxylic acid used may be one type or a mixture of two or more types.

  Preferred aliphatic monocarboxylic acids include acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, 2-ethyl-hexanecarboxylic acid, undecylic acid, lauric acid , Saturated fatty acids such as tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, heptacosanoic acid, montanic acid, melicic acid, and laccelic acid, Examples include unsaturated fatty acids such as undecylenic acid, oleic acid, sorbic acid, linoleic acid, linolenic acid, arachidonic acid and octenoic acid.

  Examples of preferable alicyclic monocarboxylic acids include acetic acid, cyclopentanecarboxylic acid, cyclohexanecarboxylic acid, cyclooctanecarboxylic acid, and derivatives thereof.

  Examples of preferred aromatic monocarboxylic acids include aromatic monocarboxylic acids having an alkyl group or alkoxy group introduced into the benzene ring of benzoic acid such as benzoic acid and toluic acid, cinnamic acid, benzylic acid, biphenylcarboxylic acid, and naphthalene. Examples thereof include aromatic monocarboxylic acids having two or more benzene rings such as carboxylic acid and tetralin carboxylic acid, or derivatives thereof. More specifically, xylyl acid, hemelic acid, mesitylene acid, prenylic acid, γ-isoduric acid, jurylic acid, mesitic acid, α-isoduric acid, cumic acid, α-toluic acid, hydroatropic acid, atropic acid, hydrocinnamic acid, salicylic acid, o-anisic acid, m-anisic acid, p-anisic acid , Creosote acid, o-homosalicylic acid, m-homosalicylic acid, p-homosalicylic acid, o-pyroca Succinic acid, β-resorcylic acid, vanillic acid, isovanillic acid, veratromic acid, o-veratrumic acid, gallic acid, asaronic acid, mandelic acid, homoanisic acid, homovanillic acid, homoveratrumic acid, o-homoveratrumic acid, phthalonic acid, p- Although coumaric acid can be mentioned, benzoic acid is particularly preferable.

  The oligosaccharide ester compound can be applied as a compound having 1 to 12 at least one of the pyranose structure or furanose structure according to the present invention.

  Oligosaccharides are produced by allowing an enzyme such as amylase to act on starch, sucrose, etc. Examples of oligosaccharides that can be applied to the present invention include maltooligosaccharides, isomaltoligosaccharides, fructooligosaccharides, galactooligosaccharides, and xylooligos. Sugar.

Moreover, the said ester compound is a compound which condensed 1 or more and 12 or less of at least 1 sort (s) of the pyranose structure or furanose structure represented with the following general formula (A). However, R < ₁₁ > -R < ₁₅ >, R < ₂₁ > -R < ₂₅ > represents a C2-C22 acyl group or a hydrogen atom, m and n represent the integer of 0-12 respectively, and m + n represents the integer of 1-12.

R _{11 to} R ₁₅ and R _{21 to} R ₂₅ are preferably a benzoyl group or a hydrogen atom. The benzoyl group may further have a substituent R ₂₆ (p is 0 to 5), and examples thereof include an alkyl group, an alkenyl group, an alkoxyl group, and a phenyl group, and further, these alkyl groups, alkenyl groups, and phenyl groups. May have a substituent. Oligosaccharides can also be produced by the same method as the ester compound of the present invention.

  Although the specific example of the ester compound which concerns on this invention is given to the following, this invention is not limited to this.

The cellulose ester film of the present invention preferably contains the ester compound of the present invention in an amount of 1 to 30% by mass of the cellulose ester film in order to suppress the fluctuation of the retardation value and stabilize the display quality. 5 to 30% by mass is preferable.
<Other additives>
(Plasticizer)
The cellulose ester film of the present invention can contain a plasticizer as necessary to obtain the effects of the present invention.

  The plasticizer is not particularly limited, but is preferably a polycarboxylic acid ester plasticizer, a glycolate plasticizer, a phthalate ester plasticizer, a fatty acid ester plasticizer, a polyhydric alcohol ester plasticizer, or a polyester plasticizer. Agent, acrylic plasticizer and the like.

  Of these, when two or more plasticizers are used, at least one is preferably a polyhydric alcohol ester plasticizer.

  The polyhydric alcohol ester plasticizer is a plasticizer composed of an ester of a divalent or higher aliphatic polyhydric alcohol and a monocarboxylic acid, and preferably has an aromatic ring or a cycloalkyl ring in the molecule. Preferably it is a 2-20 valent aliphatic polyhydric alcohol ester.

  The polyhydric alcohol preferably used in the present invention is represented by the following general formula (a).

Formula (a) R _1- (OH) _n
However, R ₁ represents an n-valent organic group, n represents a positive integer of 2 or more, and the OH group represents an alcoholic and / or phenolic hydroxyl group.

  Examples of preferred polyhydric alcohols include the following, but the present invention is not limited to these.

  Adonitol, arabitol, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propanediol, dipropylene glycol, tripropylene glycol, 1,2-butanediol, 1,3- Butanediol, 1,4-butanediol, dibutylene glycol, 1,2,4-butanetriol, 1,5-pentanediol, 1,6-hexanediol, hexanetriol, galactitol, mannitol, 3-methylpentane- Examples include 1,3,5-triol, pinacol, sorbitol, trimethylolpropane, trimethylolethane, xylitol and the like.

  In particular, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, sorbitol, trimethylolpropane, and xylitol are preferable.

  There is no restriction | limiting in particular as monocarboxylic acid used for polyhydric alcohol ester, Well-known aliphatic monocarboxylic acid, alicyclic monocarboxylic acid, aromatic monocarboxylic acid, etc. can be used. Use of an alicyclic monocarboxylic acid or aromatic monocarboxylic acid is preferred in terms of improving moisture permeability and retention.

  Examples of preferred monocarboxylic acids include the following, but the present invention is not limited thereto.

  As the aliphatic monocarboxylic acid, a fatty acid having a straight chain or side chain having 1 to 32 carbon atoms can be preferably used. The number of carbon atoms is more preferably 1-20, and particularly preferably 1-10. When acetic acid is contained, the compatibility with the cellulose ester is increased, and it is also preferable to use a mixture of acetic acid and another monocarboxylic acid.

  Preferred aliphatic monocarboxylic acids include acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, 2-ethyl-hexanoic acid, undecylic acid, lauric acid, tridecylic acid, Saturated fatty acids such as myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, heptacosanoic acid, montanic acid, melicic acid, laccelic acid, undecylenic acid, olein Examples thereof include unsaturated fatty acids such as acid, sorbic acid, linoleic acid, linolenic acid, and arachidonic acid.

  Examples of preferred alicyclic monocarboxylic acids include cyclopentane carboxylic acid, cyclohexane carboxylic acid, cyclooctane carboxylic acid, or derivatives thereof.

  Examples of preferred aromatic monocarboxylic acids include those in which 1 to 3 alkoxy groups such as alkyl group, methoxy group or ethoxy group are introduced into the benzene ring of benzoic acid such as benzoic acid and toluic acid, biphenylcarboxylic acid, Examples thereof include aromatic monocarboxylic acids having two or more benzene rings such as naphthalenecarboxylic acid and tetralincarboxylic acid, or derivatives thereof. Benzoic acid is particularly preferable.

  The molecular weight of the polyhydric alcohol ester is not particularly limited, but is preferably 300 to 1500, and more preferably 350 to 750. A higher molecular weight is preferred because it is less likely to volatilize, and a smaller one is preferred in terms of moisture permeability and compatibility with cellulose ester.

  The carboxylic acid used for the polyhydric alcohol ester may be one kind or a mixture of two or more kinds. Moreover, all the OH groups in the polyhydric alcohol may be esterified, or a part of the OH groups may be left as they are.

  Below, the specific compound of a polyhydric alcohol ester is illustrated.

  The glycolate plasticizer is not particularly limited, but alkylphthalylalkyl glycolates can be preferably used.

  Examples of alkyl phthalyl alkyl glycolates include methyl phthalyl methyl glycolate, ethyl phthalyl ethyl glycolate, propyl phthalyl propyl glycolate, butyl phthalyl butyl glycolate, octyl phthalyl octyl glycolate, methyl phthalyl ethyl Glycolate, ethyl phthalyl methyl glycolate, ethyl phthalyl propyl glycolate, methyl phthalyl butyl glycolate, ethyl phthalyl butyl glycolate, butyl phthalyl methyl glycolate, butyl phthalyl ethyl glycolate, propyl phthalyl butyl glycol Butyl phthalyl propyl glycolate, methyl phthalyl octyl glycolate, ethyl phthalyl octyl glycolate, octyl phthalyl methyl glycolate, octyl phthalate Ethyl glycolate, and the like.

  Examples of the phthalate ester plasticizer include diethyl phthalate, dimethoxyethyl phthalate, dimethyl phthalate, dioctyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate, dioctyl phthalate, dicyclohexyl phthalate, and dicyclohexyl terephthalate.

  Examples of the citrate plasticizer include acetyl trimethyl citrate, acetyl triethyl citrate, and acetyl tributyl citrate.

  Examples of fatty acid ester plasticizers include butyl oleate, methylacetyl ricinoleate, and dibutyl sebacate.

  Examples of the phosphate ester plasticizer include triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, diphenyl biphenyl phosphate, trioctyl phosphate, tributyl phosphate and the like.

  The polyvalent carboxylic acid ester compound is composed of an ester of divalent or higher, preferably divalent to 20 valent polyvalent carboxylic acid and alcohol. The aliphatic polyvalent carboxylic acid is preferably 2 to 20 valent, and in the case of an aromatic polyvalent carboxylic acid or an alicyclic polyvalent carboxylic acid, it is preferably 3 to 20 valent.

  The polyvalent carboxylic acid is represented by the following general formula (b).

Formula (b) R ₂ (COOH) _m (OH) _n
(Where R ₂ is an (m + n) -valent organic group, m is a positive integer of 2 or more, n is an integer of 0 or more, a COOH group is a carboxyl group, and an OH group is an alcoholic or phenolic hydroxyl group)
Examples of preferred polyvalent carboxylic acids include the following, but the present invention is not limited to these.

  Trivalent or higher aromatic polyvalent carboxylic acids such as trimellitic acid, trimesic acid, pyromellitic acid or derivatives thereof, succinic acid, adipic acid, azelaic acid, sebacic acid, oxalic acid, fumaric acid, maleic acid, tetrahydrophthal An aliphatic polyvalent carboxylic acid such as an acid, an oxypolyvalent carboxylic acid such as tartaric acid, tartronic acid, malic acid and citric acid can be preferably used. In particular, it is preferable to use an oxypolycarboxylic acid from the viewpoint of improving retention.

  There is no restriction | limiting in particular as alcohol used for the polyhydric carboxylic acid ester compound which can be used for this invention, Well-known alcohol and phenols can be used.

  For example, an aliphatic saturated alcohol or aliphatic unsaturated alcohol having a straight chain or a side chain having 1 to 32 carbon atoms can be preferably used. It is more preferable that it is C1-C20, and it is especially preferable that it is C1-C10.

  In addition, alicyclic alcohols such as cyclopentanol and cyclohexanol or derivatives thereof, aromatic alcohols such as benzyl alcohol and cinnamyl alcohol, or derivatives thereof can also be preferably used.

  When an oxypolycarboxylic acid is used as the polycarboxylic acid, the alcoholic or phenolic hydroxyl group of the oxypolycarboxylic acid may be esterified with a monocarboxylic acid. Examples of preferred monocarboxylic acids include the following, but the present invention is not limited thereto.

  As the aliphatic monocarboxylic acid, a fatty acid having a straight chain or a side chain having 1 to 32 carbon atoms can be preferably used. It is more preferable that it is C1-C20, and it is especially preferable that it is C1-C10.

  Preferred aliphatic monocarboxylic acids include acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, 2-ethyl-hexanecarboxylic acid, undecylic acid, lauric acid, tridecylic acid, Saturated fatty acids such as myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, heptacosanoic acid, montanic acid, melicic acid, and laccelic acid, undecylenic acid, olein Examples thereof include unsaturated fatty acids such as acid, sorbic acid, linoleic acid, linolenic acid, and arachidonic acid.

  Examples of preferred alicyclic monocarboxylic acids include cyclopentane carboxylic acid, cyclohexane carboxylic acid, cyclooctane carboxylic acid, or derivatives thereof.

  Examples of preferred aromatic monocarboxylic acids include those in which an alkyl group is introduced into the benzene ring of benzoic acid such as benzoic acid and toluic acid, and two or more benzene rings such as biphenyl carboxylic acid, naphthalene carboxylic acid, and tetralin carboxylic acid. And aromatic monocarboxylic acids possessed by them, or derivatives thereof. Particularly preferred are acetic acid, propionic acid, and benzoic acid.

  The molecular weight of the polyvalent carboxylic acid ester compound is not particularly limited, but is preferably in the range of 300 to 1000, and more preferably in the range of 350 to 750. The larger one is preferable in terms of improving the retention, and the smaller one is preferable in terms of moisture permeability and compatibility with the cellulose ester.

  The alcohol used for the polyvalent carboxylic acid ester that can be used in the present invention may be one kind or a mixture of two or more kinds.

  The acid value of the polyvalent carboxylic acid ester compound that can be used in the present invention is preferably 1 mgKOH / g or less, and more preferably 0.2 mgKOH / g or less. Setting the acid value in the above range is preferable because the environmental fluctuation of retardation is also suppressed.

  In addition, an acid value means the milligram number of potassium hydroxide required in order to neutralize the acid (carboxyl group which exists in a sample) contained in 1g of samples. The acid value is measured according to JIS K0070.

  Examples of particularly preferred polyvalent carboxylic acid ester compounds are shown below, but the present invention is not limited thereto.

  For example, triethyl citrate, tributyl citrate, acetyl triethyl citrate (ATEC), acetyl tributyl citrate (ATBC), benzoyl tributyl citrate, acetyl triphenyl citrate, acetyl tribenzyl citrate, dibutyl tartrate, diacetyl dibutyl tartrate, Examples include tributyl trimellitic acid and tetrabutyl pyromellitic acid.

  The polyester plasticizer is not particularly limited, and a polyester plasticizer having an aromatic ring or a cycloalkyl ring in the molecule can be used. Although it does not specifically limit as a polyester plasticizer, For example, the aromatic terminal ester plasticizer represented by the following general formula (c) can be used.

Formula (c) B- (GA) _n -GB
(In the formula, B is a benzene monocarboxylic acid residue, G is an alkylene glycol residue having 2 to 12 carbon atoms, an aryl glycol residue having 6 to 12 carbon atoms, or an oxyalkylene glycol residue having 4 to 12 carbon atoms, A represents an alkylene dicarboxylic acid residue having 4 to 12 carbon atoms or an aryl dicarboxylic acid residue having 6 to 12 carbon atoms, and n represents an integer of 1 or more.)
In the general formula (c), a benzene monocarboxylic acid residue represented by B and an alkylene glycol residue, oxyalkylene glycol residue or aryl glycol residue represented by G, an alkylene dicarboxylic acid residue or aryl dicarboxylic group represented by A It is composed of an acid residue and can be obtained by a reaction similar to that of a normal polyester plasticizer.

  Examples of the benzene monocarboxylic acid component of the polyester plasticizer used in the present invention include benzoic acid, para-tert-butylbenzoic acid, orthotoluic acid, metatoluic acid, p-toluic acid, dimethylbenzoic acid, ethylbenzoic acid, and normalpropyl. There exist benzoic acid, aminobenzoic acid, acetoxybenzoic acid, etc., and these can be used as 1 type, or 2 or more types of mixtures, respectively.

  Examples of the alkylene glycol component having 2 to 12 carbon atoms of the polyester plasticizer that can be used in the present invention include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1, 3-butanediol, 1,2-propanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethyl-1,3-propanediol (neo Pentyl glycol), 2,2-diethyl-1,3-propanediol (3,3-dimethylolpentane), 2-n-butyl-2-ethyl-1,3propanediol (3,3-dimethylolheptane) 3-methyl-1,5-pentanediol 1,6-hexanediol, 2,2,4-trimethyl 1,3-penta Diol, 2-ethyl 1,3-hexanediol, 2-methyl 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-octadecanediol, and the like. It is used as one kind or a mixture of two or more kinds.

  In particular, an alkylene glycol having 2 to 12 carbon atoms is particularly preferable because of excellent compatibility with a cellulose ester.

  In addition, examples of the oxyalkylene glycol component having 4 to 12 carbon atoms of the aromatic terminal ester include diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, and tripropylene glycol. It can be used as a seed or a mixture of two or more.

  Examples of the alkylene dicarboxylic acid component having 4 to 12 carbon atoms of the aromatic terminal ester include succinic acid, maleic acid, fumaric acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, and dodecanedicarboxylic acid. These are used as one kind or a mixture of two or more kinds. Examples of the arylene dicarboxylic acid component having 6 to 12 carbon atoms include phthalic acid, terephthalic acid, isophthalic acid, 1,5 naphthalene dicarboxylic acid, and 1,4 naphthalene dicarboxylic acid.

  The polyester plasticizer used in the present invention has a number average molecular weight of preferably 300 to 1500, more preferably 400 to 1000. The acid value is 0.5 mgKOH / g or less, the hydroxyl value is 25 mgKOH / g or less, more preferably the acid value is 0.3 mgKOH / g or less, and the hydroxyl value is 15 mgKOH / g or less.

  Specific examples of the aromatic terminal ester plasticizer that can be used in the present invention are shown below, but the present invention is not limited thereto.

(UV absorber)
The cellulose ester film according to the present invention can also contain an ultraviolet absorber. The ultraviolet absorber is intended to improve durability by absorbing ultraviolet light having a wavelength of 400 nm or less, and the transmittance at a wavelength of 370 nm is particularly preferably 10% or less, more preferably 5% or less. Preferably it is 2% or less.

  Although the ultraviolet absorber used in the present invention is not particularly limited, for example, oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, triazine compounds, nickel complex compounds, inorganic powders Examples include the body.

  For example, 5-chloro-2- (3,5-di-sec-butyl-2-hydroxylphenyl) -2H-benzotriazole, (2-2H-benzotriazol-2-yl) -6- (linear and side Chain dodecyl) -4-methylphenol, 2-hydroxy-4-benzyloxybenzophenone, 2,4-benzyloxybenzophenone, etc., and tinuvin 109, tinuvin 171, tinuvin 234, tinuvin 326, tinuvin 327, tinuvin 328, etc. These are commercially available products manufactured by Ciba Specialty Chemicals and can be preferably used.

  The UV absorbers preferably used in the present invention are benzotriazole UV absorbers, benzophenone UV absorbers, and triazine UV absorbers, particularly preferably benzotriazole UV absorbers and benzophenone UV absorbers. .

  In addition, a discotic compound such as a compound having a 1,3,5 triazine ring is also preferably used as the ultraviolet absorber.

  It is preferable that the polarizing plate protective film concerning this invention contains 2 or more types of ultraviolet absorbers.

  As the UV absorber, a polymer UV absorber can also be preferably used, and in particular, a polymer type UV absorber described in JP-A-6-148430 is preferably used.

  The method for adding the UV absorber is to add the UV absorber to the dope after dissolving the UV absorber in an alcohol such as methanol, ethanol or butanol, an organic solvent such as methylene chloride, methyl acetate, acetone or dioxolane, or a mixed solvent thereof. Or you may add directly in dope composition.

  For an inorganic powder that does not dissolve in an organic solvent, a dissolver or a sand mill is used in the organic solvent and cellulose ester to disperse and then added to the dope.

  The amount of the UV absorber used is not uniform depending on the type of UV absorber, the operating conditions, etc., but when the dry film thickness of the polarizing plate protective film is 30 to 200 μm, it is 0.5 with respect to the polarizing plate protective film. -10 mass% is preferable, and 0.6-4 mass% is still more preferable.

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

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

  As such an antioxidant, a hindered phenol compound is preferably used. For example, 2,6-di-t-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di- -T-butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol-bis [3 -(3,5-di-t-butyl-4-hydroxyphenyl) propionate], 2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-t-butylanilino)- 1,3,5-triazine, 2,2-thio-diethylenebis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], octa Sil-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, N, N'-hexamethylenebis (3,5-di-t-butyl-4-hydroxy-hydrocinnamamide) 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, tris- (3,5-di-t-butyl-4-hydroxy Benzyl) -isocyanurate and the like.

  In particular, 2,6-di-t-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3 -(3-t-butyl-5-methyl-4-hydroxyphenyl) propionate] is preferred. Further, for example, hydrazine-based metal deactivators such as N, N′-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyl] hydrazine and tris (2,4-di- A phosphorus processing stabilizer such as t-butylphenyl) phosphite may be used in combination.

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

(Fine particles)
The cellulose ester film according to the present invention preferably contains fine particles.

  As fine particles used in the present invention, examples of inorganic compounds include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, and hydrated silicic acid. Mention may be made of calcium, aluminum silicate, magnesium silicate and calcium phosphate.

  Fine particles containing silicon are preferable in terms of low turbidity, and silicon dioxide is particularly preferable.

  The average primary particle diameter of the fine particles is preferably 5 to 400 nm, and more preferably 10 to 300 nm.

  These may be mainly contained as secondary aggregates having a particle size of 0.05 to 0.3 μm, and may be contained as primary particles without being aggregated if the particles have an average particle size of 100 to 400 nm. preferable.

  The content of these fine particles in the cellulose ester film is preferably 0.01 to 1% by mass, particularly preferably 0.05 to 0.5% by mass. In the case of a polarizing plate protective film having a multilayer structure by the co-casting method, it is preferable to contain fine particles of this addition amount on the surface.

  Silicon dioxide fine particles are commercially available, for example, under the trade names Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, TT600 (manufactured by Nippon Aerosil Co., Ltd.). it can.

  Zirconium oxide fine particles are commercially available, for example, under the trade names Aerosil R976 and R811 (manufactured by Nippon Aerosil Co., Ltd.) and can be used.

  Examples of the polymer include silicone resin, fluororesin, and acrylic resin. Silicone resins are preferable, and those having a three-dimensional network structure are particularly preferable. For example, Tospearl 103, 105, 108, 120, 145, 3120, and 240 (manufactured by Toshiba Silicone Co., Ltd.) It is marketed by name and can be used.

  Among these, Aerosil 200V and Aerosil R972V are particularly preferably used because they have a large effect of reducing the friction coefficient while keeping the turbidity of the polarizing plate protective film low. In the polarizing plate protective film used in the present invention, the dynamic friction coefficient of at least one surface is preferably 0.2 to 1.0.

  Various additives may be batch-added to a dope that is a cellulose ester-containing solution before film formation, or an additive solution may be separately prepared and added in-line. In particular, it is preferable to add a part or all of the fine particles in-line in order to reduce the load on the filter medium.

  When the additive solution is added in-line, it is preferable to dissolve a small amount of cellulose ester in order to improve mixing with the dope. The amount of the cellulose ester is preferably 1 to 10 parts by mass, more preferably 3 to 5 parts by mass with respect to 100 parts by mass of the solvent.

In order to perform in-line addition and mixing in the present invention, for example, an in-line mixer such as a static mixer (manufactured by Toray Engineering), SWJ (Toray static type in-tube mixer Hi-Mixer) or the like is preferably used.
<Method for producing roll-shaped retardation film>
Next, the manufacturing method of the cellulose-ester film which is a roll-like retardation film of this invention is demonstrated.

  The cellulose ester film according to the present invention can be preferably used regardless of whether it is a film produced by a solution casting method or a film produced by a melt casting method.

  The cellulose ester film of the present invention is produced by dissolving a cellulose ester and an additive in a solvent to prepare a dope, casting and drying on an endless metal support that moves the dope indefinitely, a metal support The film is peeled from the film, stretched, further dried, and the finished film is wound.

<Solution casting method>
<Dope adjustment process>
The process for preparing the dope will be described. The concentration of cellulose ester 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 ester 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 in the dope may be used alone or in combination of two or more, but it is preferable to use a mixture of a good solvent and a poor solvent of cellulose ester in terms of production efficiency, and there are many good solvents. This is preferable from the viewpoint of the solubility of the cellulose ester.

  The preferable range of the mixing ratio of the good solvent and the poor solvent is 70 to 98% by mass for the good solvent and 2 to 30% by mass for the poor solvent. With a good solvent and a poor solvent, what dissolve | melts the cellulose ester to be used independently is defined as a good solvent, and what poorly swells or does not melt | dissolve is defined as a poor solvent.

  Therefore, depending on the average acetylation degree (acetyl group substitution degree) of the cellulose ester, the good solvent and the poor solvent change. For example, when acetone is used as the solvent, the cellulose ester acetate ester (acetyl group substitution degree 2.4), cellulose Acetate propionate is a good solvent, and cellulose acetate (acetyl group substitution degree 2.8) is a poor solvent.

  Although the good solvent used for this invention is not specifically limited, Organic halogen compounds, such as a methylene chloride, dioxolanes, acetone, methyl acetate, methyl acetoacetate, etc. are mentioned. Particularly preferred is methylene chloride or methyl acetate.

  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 ester 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 the cellulose ester, such as plasticizers, UV absorbers, polymers, monomer components, etc., but even if these are included, they are preferably reused. Can be purified and reused if necessary.

  A general method can be used as a dissolution method of the cellulose ester when preparing the dope described above. 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.

  Moreover, after mixing a cellulose ester with a poor solvent and making it wet or swell, the method of adding a good solvent and melt | dissolving is also used preferably.

  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 the cellulose ester, 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 still more preferably 70 ° C to 105 ° C. 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 the cellulose ester can be dissolved in a solvent such as methyl acetate.

  Next, this cellulose ester 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 with an absolute filtration accuracy of 0.008 mm or less is preferable, a filter medium with 0.001 to 0.008 mm is more preferable, and a filter medium with 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 ester by filtration.

Bright spot foreign matter means that when two polarizing plates are placed in a crossed Nicol state, an optical 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 appears to leak, 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, more preferably 1.2 MPa or less, and further preferably 1.0 MPa or less.

  Here, the dope casting will be described.

<Casting and drying process>
The metal support in the casting (casting) step preferably has 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 body temperature is 0-40 degreeC, and 5-30 degreeC is still more preferable. 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.

<Peeling process>
In order for the cellulose ester film to exhibit good flatness, 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.

  Further, in the drying step of the cellulose ester film, the web is peeled off from the metal support, and further dried, and the residual solvent amount is preferably 1% by mass or less, more preferably 0.1% by mass or less, Especially preferably, it is 0-0.01 mass% or less. Peeling is preferably performed at a peeling tension of 300 N / m or less.

<Extension process>
In order to obtain the target retardation values Ro and Rt in the present invention, it is preferable that the cellulose ester film has the configuration of the present invention and further the refractive index is controlled by a stretching operation.

  The present invention is characterized in that the slow axis is 45 ± 5 ° with respect to the longitudinal direction. For this purpose, a method of stretching by adjusting the angle is adopted.

  As a method of adjusting the angle, it is preferable to stretch or regulate shrinkage in the film forming direction, and then stretch or regulate shrinkage in the inclined direction with respect to the film forming direction. For example, Japanese Patent Application Laid-Open No. 2003-340916 No. 2005-284024 shown in FIG. 4, a method using the drawing apparatus described in Production Example 2, and No. 2007-30466. Can be preferably used, and the method using the stretching apparatus used in Example 1 of JP-A-2007-94007 can be preferably used. It may be stretched again later.

  Most preferably, the method described in JP-A-2005-30466 is used.

Further, the following methods may be used in combination.
(1) Method of bending the left and right path by bending the conveyance (2) Method of setting the right and left clip speed difference by the spindle (3) Method of giving the right and left speed difference by giving independent left and right bending angles The embodiment will be described with reference to the drawings in the case of oblique stretching.

  2 and 3 show a plane and a cross section of a film stretching apparatus (stretching apparatus) 1 which is an embodiment of the present invention. The film stretching apparatus 1 includes a supply device 3 that supplies the film 2, a longitudinal stretching device 4 that heats the film, and a longitudinal stretching process (longitudinal stretching process) 6 that includes an intermediate transport device 5 that transports the film 2 downstream. An oblique stretching machine 7 that is inclined with respect to the transport direction while transporting the film 2 and that stretches in the direction, and an oblique stretching heating device that is provided so as to cover the central portion of the oblique stretching machine 7 and heats the film 2 8 includes an oblique stretching process (orthogonal expansion / contraction process) 9 and a winding device 10 for winding the film 2.

  The supply device 3 is mounted with an original reel 11 around which a film 2 is wound, and the film 2 is sandwiched between a reference roll 12 and a nip roll 13 and sent out at a predetermined transport speed. The longitudinal stretching device 4 is a box made of a heat insulating material having hot air ducts (heating means) 14 for spraying hot air alternately on the film 2 from above and below. The intermediate conveyance device 5 sandwiches and conveys the film 2 between the ratio roll 15 and the nip roll 16 and stretches it in the E1 direction parallel to the conveyance direction.

  The oblique stretching machine 7 stretches the film 2 in the E2 direction inclined by an angle α with respect to the transport direction while transporting the film 2 with the stretching chains 17 disposed on both sides of the film 2. Details will be described later. The oblique stretching furnace 8 is a box made of a heat insulating material having a hot air duct 18 for blowing hot air from above and below the film 2.

  The winding device 10 winds the film 2 around the product reel 20 while adjusting the tension with the tension roll 19.

  The draw ratio in the biaxial direction is preferably in the range of 0.8 to 1.5 times in the casting direction and 1.1 to 2.5 times in the width direction, respectively, and 0 in the casting direction. It is preferable to carry out in the range of 0.8 to 1.0 times and 1.2 to 2.0 times in the width direction.

  The stretching temperature is preferably 120 ° C. to 210 ° C., more preferably 160 ° C. to 200 ° C., and more preferably over 170 ° C. and 200 ° C. or less.

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

  Specifically, the residual solvent is preferably stretched at 11% at 175 ° C., or the residual solvent is stretched at 2% at 175 ° C. Alternatively, it is preferred that the residual solvent is stretched at 11% at 185 ° C., or it is preferred that the residual solvent is stretched at less than 1% at 185 ° C.

  The slow axis or the fast axis of the cellulose ester film of the present invention exists in the film plane, and θ1 is preferably 45 ° ± 5 °, assuming that the angle formed with the film forming direction is θ1, and 45 ° ± 3 More preferably.

  This θ1 can be defined as an orientation angle, and θ1 can be measured using an automatic birefringence meter KOBRA-21ADH (Oji Scientific Instruments). Each of θ1 satisfying the above relationship can contribute to obtaining high luminance in a display image, suppressing or preventing light leakage, and contributing to obtaining faithful color reproduction in a color liquid crystal display device.

<Drying process>
In the film drying step, generally, a roll drying method (a method in which webs are alternately passed through a plurality of rolls arranged above and below) and a method in which the web is dried while being conveyed by a tenter method are employed.

  The means for drying is not particularly limited and can be generally performed with hot air, infrared rays, a heating roll, microwave, or the like, but is preferably performed with hot air from the viewpoint of simplicity.

  The drying temperature in the drying step is preferably increased stepwise from 40 to 200 ° C.

  Although the film thickness of a cellulose-ester film is not specifically limited, 10-200 micrometers is used. In particular, the film thickness is particularly preferably 10 to 100 μm. More preferably, it is 20-60 micrometers.

  The cellulose ester film of the present invention has a width of 1 to 4 m. In particular, those having a width of 1.4 to 4 m are preferably used, and particularly preferably 1.6 to 3 m. If it exceeds 4 m, conveyance becomes difficult.

<Melt casting method>
The cellulose ester of the present invention is usually obtained in powder form. In the method for producing a cellulose ester film of the present invention, a powdery cellulose ester may be used, but it is preferable from the viewpoint of handling that the powder is formed into a pellet.

  When the powder is formed into a pellet, a known single-screw extruder or twin-screw extruder can be used. For example, after putting powdery cellulose ester from the hopper of an extruder, melt-kneading the cellulose ester at a temperature of about (Tg + 100) ° C., extruding a strand from the die, and cooling the strand by a method such as water cooling The pellet can be obtained by cutting with a pelletizer.

  Add various antioxidants such as phenolic antioxidants and phosphorus antioxidants, lubricants such as higher fatty acid amides and higher fatty acid residual metal salts, etc. as necessary when adding powdered cellulose ester to the hopper And may be pelletized.

  The powder is preferably dried at a temperature near Tg in advance. Moreover, when shape | molding to a pellet form, it is preferable to shape | mold, sucking the inside of an extruder using an extruder with a vent.

  Pellets made of cellulose ester are preferably used after sufficiently drying at a temperature near Tg. In order to prevent the polymer from being oxidized and deteriorated during drying, drying under nitrogen is desirable.

  The cellulose ester is melt-kneaded in a single-screw or twin-screw extruder and extruded into a sheet form from a casting die. Usually, the temperature of the extruder is set so that the resin temperature is in the range of (Tg + 100) ° C. to (Tg + 200) ° C.

  Also, the extruder hopper is sealed with nitrogen to suppress the degradation of cellulose ester in the extruder, a leaf disc filter is used to suppress the generation of foreign matter such as fish eyes, and extrusion fluctuations are suppressed. For this purpose, a gear pump may be used.

  It is preferable to use a casting die having a shape in which the tip portion is processed into a sharp edge (curvature radius R = 0.1 μm or less) from the viewpoint of suppressing occurrence of a crack.

  The molten cellulose ester extruded in a sheet form from a casting die is provided with a cooling casting roll which is a rotating support of the present invention, and a sandwich according to the present invention provided so as to be in pressure contact with the casting roll along its circumferential direction. A nip is formed by a metal elastic touch roll or endless belt, which is a pressure rotating body, and a sheet-like molten cellulose ester is passed through the nip portion, whereby the casting roll and the elastic touch roll or endless belt A cellulose ester film having a desired surface shape, thickness and optical performance is formed by sandwiching.

  Examples of the elastic touch roll of the present invention include JP-A-03-124425, JP-A-08-224772, JP-A-07-1000096, JP-A-10-272676, WO97-028950, JP-A-11-235747, JP-A-11-235747. Although the surface as described in 2002-36332, Unexamined-Japanese-Patent No. 2005-172940, or Unexamined-Japanese-Patent No. 2005-280217 can use a silicon rubber roll with a thin film metal sleeve, it must be a touch roll which has elasticity. preferable.

  The endless belt of the present invention is a flexible metal sleeve belt which is held by a plurality of rolls arranged in parallel with the casting roll in the circumferential direction of the casting roll, and has a thickness of 100 to 1500 μm. It is preferable.

  If the endless belt is too thin, the strength of the belt is weak, and the belt may be deformed when the molten cellulose ester is sandwiched. If the endless belt is too thick, the pressure for sandwiching the molten cellulose ester becomes too strong, and a bank may be formed.

  The endless belt is preferably held by two or more rolls having a diameter of 100 to 300 mm. By holding the endless belt with the roll as described above, the molten cellulose ester can be pinched with a stable pressure.

  The surface temperature of the endless belt is preferably 50 ° C. or more and (Tg−5) ° C. or less from the viewpoint of peeling failure.

  In the production apparatus of the present invention, the length (air gap) until the molten cellulose ester extruded from the lip of the casting die comes into contact with the elastic touch roll endless belt or the casting roll is 30 to 300 mm, preferably 70. ~ 200 mm.

  By producing under such conditions, a non-oriented and optically uniform film can be obtained. The air gap is the shortest length from the lip of the casting die until the molten cellulose ester contacts either the endless belt or the casting roll.

  For example, when the molten cellulose ester comes into contact with the endless belt first, it is the shortest length from the casting die lip to the point where the endless belt and the molten cellulose ester start to contact.

  The air gap when the molten cellulose ester comes into contact with the casting roll is also determined in the same manner. The value of the air gap can be determined by the size of the endless belt and the casting roll, the shape of the casting die tip, and the positional relationship between the casting roll, the endless belt and the casting die.

  In order to make the air gap 150 mm or less, it is preferable to use a 200 to 400 mmφ casting roll. The surface of the casting roll is preferably a mirror finish with high smoothness.

  The lower limit value of the surface temperature of the casting roll is preferably equal to or higher than the surface temperature of the elastic touch roll or the endless belt from the viewpoint of suppressing generation of wavy wrinkles and peeling, and the upper limit value is It is preferable that it is (Tg-5) degrees C or less.

  In the production method of the present invention, the distance for sandwiching the molten cellulose ester between the casting roll and the elastic touch roll or the endless belt is 50 to 150 mm from the viewpoint of improving the appearance defect such as a die line, preferably Is 70-130 mm.

  The cellulose ester film sandwiched between an elastic touch roll or an endless belt and a casting roll and solidified by cooling is preferably further stretched by 1.01 to 5.0 times in at least one direction. The sharpness of the streaks becomes gentle by stretching and can be highly corrected.

  The stretching apparatus is preferably the same as that used in the solution casting method.

  Thereafter, the film is taken up by a take-up machine, and after the film is slit and removed, the film is taken up in a roll by a take-up machine.

  A protective film can also be bonded using a nip roll of a take-up machine. As the protective film, a film made of a commercially available ethylene-vinyl acetate copolymer or the like can be used, and can be bonded to one side or both sides of a cellulose ester film.

  The film made of cellulose ester obtained in the present invention may be a multilayer film. In the case of a multilayer film, it is only necessary to have one or more layers made of cellulose ester.

When using the film obtained by this invention for an optical product, it is preferable that all the layers are multilayer films which consist of a cellulose ester. When a multilayer film is produced according to the present invention, a multi-manifold type casting die or a feed block type casting die can be used. Since it is easy to accurately control the thickness of each layer, it is preferable to use a multi-manifold casting die.
<Physical properties of cellulose ester film>
The moisture permeability of the cellulose ester film of the present invention, 40 ° C., of preferably 10~1200g / m ² · 24h at 90% RH, further 20~1000g / m ² · 24h are preferred, 20~850g / m ² · 24h Particularly preferred. The moisture permeability can be measured according to the method described in JIS Z 0208.

  The cellulose ester film according to the present invention preferably has a breaking elongation of 10 to 80%, more preferably 20 to 50%.

  The visible light transmittance of the cellulose ester film according to the present invention is preferably 90% or more, and more preferably 93% or more.

Further, by applying a liquid crystal layer to the cellulose ester film of the present invention, retardation values over a wider range can be obtained.
<Vertical alignment liquid crystal layer>
The retardation film of the present invention can have a layer (vertical alignment liquid crystal layer) obtained by applying and fixing liquid crystal molecules oriented in the thickness direction of the film on the film.

  This vertically aligned liquid crystal layer is preferably provided when the retardation of the retardation film is further adjusted.

  In the vertical alignment liquid crystal layer of the present invention, a liquid crystal material or a liquid crystal solution is applied onto the roll-shaped cellulose ester film which is the base material of the present invention, dried and heat-treated (also referred to as alignment treatment), and then UV-cured or heated. It is preferable to fix the liquid crystal alignment by polymerization or the like to obtain a roll-like retardation film made of a rod-like liquid crystal aligned in the vertical direction, and cut and use it appropriately.

  Here, the term “aligned in the vertical direction” means that the rod-like liquid crystal molecules are aligned in a range of 70 to 90 ° (strict vertical direction is 90 °) with respect to the film surface. The rod-like liquid crystal may be oriented obliquely or the orientation angle may be gradually changed. Preferably it is the range of 80-90 degrees.

  The vertically aligned liquid crystal layer of the present invention is a retardation film made of rod-like liquid crystal aligned in the vertical direction in which the in-plane retardation value Ro is 0 to 10 nm and the thickness retardation value Rt is in the range of −50 to −400 nm. Preferably there is. Further, Ro is more preferably in the range of 0 to 5 nm.

  Here, Rt is defined by the following formula.

Rt = {(nx + ny) / 2−nz} × d
(Where nx is the refractive index in the slow axis direction in the retardation film plane (maximum refractive index in the plane), and ny is the refractive index in the direction perpendicular to the slow axis in the retardation film plane) Nz is the refractive index in the thickness direction of the film, and d is the thickness (nm) of the retardation film.)
For the measurement of the phase difference value, an automatic birefringence meter KOBRA-21ADH (manufactured by Oji Scientific Instruments) or the like can be used.

  The Rt of the vertical alignment liquid crystal layer is intended to improve the viewing angle characteristics of the circularly polarizing film by setting the Rt of the base film so as to cancel out. Therefore, the Rt of the vertical alignment liquid crystal layer depends on the Rt of the base film. It is important to appropriately select coating conditions (such as the type of liquid crystal molecules, the concentration of liquid crystal molecules in the coating solution, and the thickness after drying). For example, when the vertical alignment liquid crystal layer is formed under the same liquid crystal molecules and the same coating liquid conditions using materials having different Rt of the base film, in order to provide excellent viewing angle characteristics as a circularly polarizing film, The object can be achieved by changing the thickness of the vertically aligned liquid crystal layer according to the value of Rt of the material film.

  When a rod-like liquid crystal layer is formed by aligning rod-like liquid crystals, an alignment film coated with a vertical alignment agent that aligns so-called liquid crystal materials in the vertical direction is used, and the liquid crystal material is vertically oriented and then fixed. be able to.

  When the liquid crystal material itself is aligned in the vertical direction at the air interface, the alignment regulating force extends to the interface opposite to the air interface, and the alignment film is not particularly necessary, and this is also preferable from the viewpoint of simplifying the configuration. preferable.

  As a specific method for vertically aligning the liquid crystal material, an alignment film composed of a cross-linked product of a block polymer composition containing a (meth) acrylic block polymer described in JP-A-2005-148473 and the like is used. Known methods such as a method of using, a method of using a vertical alignment film described in JP 2005-265889 A, and a method of using an air interface vertical alignment agent can be used.

  In order to bring the rod-shaped liquid crystal layer into the above range, it is preferable to control the alignment of the rod-shaped liquid crystal layer, the film thickness control, the temperature during UV curing, the tilt angle control, and the pretilt angle at the support / air interface.

  The liquid crystal layer is formed by curing a liquid crystal material capable of forming a liquid crystal phase at a predetermined temperature with a predetermined liquid crystal regularity. The upper limit of the temperature showing the liquid crystal phase is not particularly limited as long as the cellulose ester film of the base material is not damaged.

  Specifically, a temperature of 120 ° C. or lower is preferable from the viewpoint of easy control of process temperature and maintenance of dimensional accuracy, and a liquid crystal material that becomes a liquid crystal phase at a temperature of 100 ° C. or lower is preferably used. On the other hand, the lower limit of the temperature showing the liquid crystal phase can be said to be a temperature at which the liquid crystal material can maintain the alignment state when used as a polarizing plate.

  As the liquid crystal material used for the rod-like liquid crystal layer of the present invention, a polymerizable liquid crystal material is preferably used. The polymerizable liquid crystal material can be used by being polymerized by irradiating with predetermined actinic radiation. In the polymerized state, the vertical alignment state is fixed.

  As the polymerizable liquid crystal material, any of a polymerizable liquid crystal monomer, a polymerizable liquid crystal oligomer, and a polymerizable liquid crystal polymer can be used, and they can also be mixed with each other.

  Of the above, a polymerizable liquid crystal monomer is preferably used as the polymerizable liquid crystal material because of its high sensitivity during alignment and easy vertical alignment.

  For example, as a polymerizable rod-like liquid crystalline compound, Makromol. Chem. 190, 2255 (1989), Advanced Materials 5, 107 (1993), US Pat. Nos. 4,683,327, 5,622,648, and 5,770,107, International Publication WO95 / 22586. No. 95/24455, No. 97/00600, No. 98/23580, No. 98/52905, JP-A-1-272551, No. 6-16616, No. 7-110469. 11-80081, JP 2001-328773, JP 2004-240188, JP 2005-99236, JP 2005-99237, JP 2005-121827, JP It is possible to use the compounds described in 2002-30042 wear.

  As commercially available compounds, UCL-018 (Dainippon Ink Chemical Co., Ltd.), Palio Color LC242 (BASF Co., Ltd.), etc. can be used.

  The vertically aligned liquid crystal layer of the present invention can be produced using a known method.

<Linear polarizing film>
The linear polarizing film is not limited as long as it is an absorption linear polarizing film, and various known forms can be applied. Generally, a film made of a hydrophilic polymer such as polyvinyl alcohol is treated with a dichroic dye such as iodine and stretched, or a plastic film such as polyvinyl chloride is treated to produce polyene. In addition to a polarizing film made of an oriented film or the like, a film in which the polarizing film is covered with a sealing film and protected is used.

<Configuration of circularly polarizing film>
The cross-sectional structure of the circularly polarizing film of this invention is shown with a figure. 7 to 9 are schematic views of the embodiment of the present invention, but the present invention is not limited to this.

  FIG. 5 shows a conventional polarizing plate (having a structure of TAC (cellulose triacetate) / polarizer / TAC) and one side of a retardation film having a vertically aligned liquid crystal layer of the present invention, using an adhesive or an adhesive. It is a bonded circularly polarizing plate. In this case, a commercially available polarizing plate can be used as it is.

  FIG. 6 shows one retardation film (λ / 4) coated with the vertical alignment liquid crystal layer of the present invention, one retardation film (λ / 2) formed only by conventional oblique stretching, It is a circularly polarizing plate in which a linearly polarizing plate is bonded at an axial angle as shown in the figure.

  FIG. 7 shows a circularly polarizing plate in which the retardation film of the present invention is used as a polarizing plate protective film on one side and laminated and bonded together with another polarizing plate protective film with a linear polarizer film interposed therebetween. Under the present circumstances, the bonding surface of the retardation film of this invention is a surface on the opposite side to the surface which provided the vertical alignment liquid crystal layer.

<Configuration of organic EL element>
FIG. 8 is a schematic view of a preferred embodiment when the circularly polarizing element of the present invention is used for an organic EL (electroluminescence) element.

  As shown in FIG. 8, the EL device 300 according to this embodiment is the present invention cut out from the circularly polarizing film of the present invention, which is a laminate of the absorption linear polarizing plate 301 and the retardation film 302 of the present invention. The circularly polarizing plate 303 is provided.

  The linearly polarized light transmitted through the absorption linear polarizing plate 301 is converted into circularly polarized light by the retardation film 302.

  In addition, the EL element 300 includes a transparent substrate 304 disposed opposite to the circularly polarizing plate 303, an anode 305 formed on the transparent substrate 304, a cathode 306 disposed opposite to the anode 305, and the anode 305 and the cathode 306. A light emitting layer 307 disposed therebetween.

  In the EL element 300 having such a structure, electrons are injected from the cathode 306 and holes are injected from the anode 305, and both are recombined in the light emitting layer 307, whereby visible light corresponding to the light emission characteristics of the light emitting layer 307 is obtained. Luminescence occurs. The light generated in the light emitting layer 307 is directly or after being reflected by the cathode 306, and then extracted to the outside through the anode 305, the transparent substrate 304, and the circularly polarizing plate 303 of the present invention.

  On the other hand, half of the external light I1 (external light incident from a direction perpendicular to the surface of the absorption linear polarizing plate 301) incident from the outside of the EL element 300 due to room lighting or the like is absorbed by the absorption linear polarizing plate 301, The other half is transmitted as linearly polarized light and enters the retardation film 302.

  As described above, the light incident on the retardation film 302 is arranged so that the optical axes of the absorption linear polarizing plate 301 and the retardation film 302 intersect at 45 degrees or 135 degrees. By passing through 303, it is converted into circularly polarized light.

  When the circularly polarized light emitted from the circularly polarizing plate 303 is specularly reflected by the cathode 306, the phase is inverted by 180 degrees and reflected as reversely circularly polarized light.

  Since the reflected light R1 is incident on the circularly polarizing plate 303 again, the reflected light R1 is converted into linearly polarized light parallel to the absorption axis (the axis perpendicular to the optical axis) of the absorbing linearly polarizing plate 301. All of them are absorbed at 301 and are not emitted to the outside.

  The circularly polarizing plate of the present invention can be used not only for the bottom emission method but also for the top emission method.

Hereinafter, although an example is given and the present invention is explained, the present invention is not limited to these.
Example 1
<Preparation of roll-like retardation film-1>
A roll-like retardation film-1 was produced by the solution casting method as follows.

<Fine particle dispersion>
Fine particles 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 additive solution>
Methylene chloride 99 parts by weight Cellulose ester A 4 parts by weight Fine particle dispersion 11 parts by weight Cellulose ester A was added to a dissolution tank containing methylene chloride, heated to completely dissolve, and then made by Azumi Filter Paper Co., Ltd. No. Azumi filter paper No. Filtered using 244.

  The fine particle dispersion was slowly added thereto while sufficiently stirring the filtered cellulose ester solution. Further, the particles were dispersed by an attritor so that the secondary particles had a predetermined particle size. This was filtered with Finemet NF manufactured by Nippon Seisen Co., Ltd. to prepare a fine particle additive solution having the above composition.

  A main dope solution having the following composition was prepared. First, methylene chloride and ethanol were added to the pressure dissolution tank. Cellulose ester A was added to a pressurized dissolution tank containing a solvent while stirring. This was heated and stirred to completely dissolve, and a plasticizer and an ultraviolet absorber were further added and dissolved. This was designated as Azumi Filter Paper No. The main dope solution was prepared by filtration using 244. The materials used are shown in Table 1.

<Composition of main dope solution>
Methylene chloride 300 parts by mass Ethanol 57 parts by mass Cellulose ester A 100 parts by mass Acrylic polymer of the present invention Table 2 Sugar ester compound of the present invention Table 2 Plasticizer (A), (B), (C) 1: 1 : 1 mass ratio 0.5 parts by weight Trimethylolpropane tris (3,4,5-trimethoxybenzoate)
5.5 parts by mass In addition to 100 parts by mass of the main dope solution and 2 parts by mass of the fine particle additive solution, the mixture is thoroughly mixed with an in-line mixer (Toray static in-pipe mixer Hi-Mixer, SWJ), and then the belt is cast. Using the apparatus, it was cast uniformly on a stainless steel band support having a width of 2 m.

  On the stainless steel band support, the solvent was evaporated until the residual solvent amount became 110%, and the stainless steel band support was peeled off.

  Thereafter, using the apparatus (stretching apparatus 1) described in Example 1 of Japanese Patent Application Laid-Open No. 2007-94007, the temperature is 185 ° C., the magnification is 1.5 times, and the slow axis is 45 ° with the film width direction. It carried out to the direction and it was made to dry and the roll-shaped retardation film-1 was obtained.

<Preparation of roll-like retardation film-2>
In the production of the roll-like retardation film-1, the stretching apparatus was changed to the apparatus (stretching apparatus 2) described in Example 1 of Japanese Patent Application Laid-Open No. 2003-340916, and was delayed at a temperature of 185 ° C. and a magnification of 1.5 times. It was performed in an oblique direction so that the phase axis formed 45 ° with the film width direction.

<Preparation of roll-like retardation film-3>
In the production of the roll-like retardation film-1, the stretching apparatus was changed to the apparatus (stretching apparatus 3) described in JP-A-2007-30466, and the slow axis was 185 ° C. and the magnification was 1.5 times. It was performed in an oblique direction so as to form 45 ° with the film width direction.

<Preparation of roll-like retardation film-4, 5>
In the production of the roll-like retardation film-1, the acrylic polymer and sugar ester compound of the present invention were modified as shown in Table 2.

<Preparation of roll-like retardation film-6>
In the production of the roll-like retardation film-1, the total amount of the plasticizers (A), (B), and (C) is changed to 5.5 parts by mass instead of the acrylic polymer and sugar ester compound of the present invention. And made.

  A part of the obtained roll-like retardation film was cut out and evaluated for haze and scattered light intensity. The results are shown in Table 2.

<< Measurement of Retardation Ro, Rt >>
A 35 mm × 35 mm sample was cut out from the obtained film, conditioned at 25 ° C. and 55% RH for 2 hours, and measured with an automatic birefringence meter (KOBRA21DH, Oji Scientific Co., Ltd.) from the vertical direction at 590 nm and the film. It calculated from the extrapolation value of the retardation value measured similarly, inclining a surface.

《Haze》
Measurement was performed according to JIS K-6714 using a haze meter 1001DP type, manufactured by Nippon Denshoku Industries Co., Ltd.

<Intensity of scattered light>
Goniophotometer model: GP-1-3D, manufactured by Optec Corporation (light source: 12V50W halogen bulb, light receiving part: photomultiplier tube (Photomaru Hamamatsu Photonics R636-10)).

  The amount of light at the time of measurement was corrected with the amount of light at θ = 180 ° (photomal light receiving sensitivity: −185 V), and the measured value at this amount of light was taken as the scattered light intensity.

  The sample was measured by fixing the slow axis of the film horizontally and vertically on the sample stage.

Example 2
<Preparation of roll-like retardation film-7>
A roll-like retardation film-7 was produced by the melt casting method using the apparatus shown in FIG. 9 as follows.

(Pellet preparation)
Cellulose ester B 100 parts by mass Acrylic polymer of the invention Table 3 Sugar ester compound of the invention Table 3 (Drying at 130 ° C. for 5 hours, glass transition point: Tg = 174 ° C.)
Trimethylolpropane tris (3,4,5-trimethoxybenzoate)
1 part by mass IRGANOX-1010 (manufactured by Ciba Specialty Chemicals Inc.) 1 part by mass Sumilizer GP (manufactured by Sumitomo Chemical Co., Ltd.) 0.5 part by mass Silica particles (average particle size 0.1 μm) 0.05 parts by mass In addition, after mixing for 30 minutes in a V-type mixer filled with nitrogen gas, it was melted at 240 ° C. using a twin screw extruder (PCM30, Ikegai Co., Ltd.) equipped with a strand die, 4 mm in length and diameter A 3 mm cylindrical pellet was produced. At this time, the shear rate was set to 25 (mm / s).

  The obtained pellets were dried at 100 ° C. for 5 hours to have a water content of 100 ppm and supplied to a single screw extruder (GT-50; manufactured by Plastic Engineering Laboratory Co., Ltd.) equipped with a 300 mm wide T-die. And T-die was set to 250 degreeC and it formed into a film.

  The surface of the T die was subjected to hard chrome plating and finished with a mirror finish with a surface roughness of 0.1S. The film from the T-die was dropped onto a first cooling roll with a chrome-plated mirror surface adjusted to 110 ° C.

  The film in close contact with the first cooling roll was pressed with an elastic touch roll after being transported around the circumference of the first cooling roll by a central angle of 10 °. At this time, it contacted with the pressure of 4 N / mm with respect to the whole width 250mm of a film.

  The pressed film comes into contact with the circumferential portion of the first cooling roll 5 with a central angle of 150 °, and further, a total of three coolings of a second cooling roll (temperature 110 ° C.) and a third cooling roll (temperature 80 ° C.). The film was sequentially circumscribed on the roll, cooled and solidified to form a film, and peeled off by a peeling roll.

  Thereafter, using the stretching apparatus 1, the temperature is 170 ° C., the magnification is 1.25 times, and the slow axis is 45 ° to the film width direction, and the film is dried and dried to obtain a roll-like retardation film-7. It was.

  The same retardation films-8 to 19 were prepared by changing the acrylic polymer and the sugar ester compound of the present invention as shown in Table 3.

  Cellulose ester C was used in retardation film-12, and cellulose ester D was used in retardation film-15 in the same amount as retardation film-7.

  In the retardation film 17, 5 parts by mass of trimethylolpropane tris (3,4,5-trimethoxybenzoate) was used instead of the acrylic polymer and sugar ester compound of the present invention.

  A part of the obtained roll-like retardation film was cut out and evaluated for haze and scattered light intensity. The results are shown in Table 3.

The sample of the present invention has a small difference in haze and scattered light intensity and is good.
Example 3
A circularly polarizing plate was produced using the roll retardation film.

(Production of circularly polarizing plate)
The coating liquid D-1 containing the following vertically aligned liquid crystal compound is applied to one surface of Samples 1 to 19 of Examples 1 and 2, dried with hot air, and then UV irradiated to cure the entire layer. It was. The thickness of the vertically aligned liquid crystal layer was adjusted so that Rt = 0 ± 3 nm.

Vertical alignment liquid crystal compound: Dainippon Ink & Chemicals, Inc. UCL-018
16 parts by mass Methyl ethyl ketone 16.8 parts by mass Propylene glycol monomethyl ether 67.2 parts by mass Next, a 120 μm-thick polyvinyl alcohol long film was uniaxially stretched in the MD direction (temperature 110 ° C., stretch ratio 5 times). This was immersed in an aqueous solution composed of 0.075 g of iodine, 5 g of potassium iodide and 100 g of water for 60 seconds, and then immersed in an aqueous solution of 68 ° C. composed of 6 g of potassium iodide, 7.5 g of boric acid and 100 g of water. This was washed with water and dried to obtain a roll-shaped polarizer.

  Next, according to the following steps 1 to 5, the polarizer, the roll-like retardation films -1 to 19 described in Examples 1 and 2, and the roll-like Konica Minolta Tack KC4UY (Konica Minolta Opto Corporation) ) Made as a polarizing plate protective film in the longitudinal direction, and circularly polarizing plates 1 to 19 were produced.

  Process 1: It is immersed in a 2 mol / L sodium hydroxide solution at 60 ° C. for 90 seconds, then washed with water and dried, and the side to be bonded to the polarizer (the surface on which the vertical alignment liquid crystal layer is not applied) A saponified retardation film was obtained.

  Process 2: The said polarizer was immersed in the polyvinyl alcohol adhesive tank of 2 mass% of solid content for 1-2 seconds.

  Step 3: Excess adhesive adhered to the polarizer in Step 2 was lightly wiped off, and this was placed on the cellulose ester film treated in Step 1.

Step 4: Step 3 retardation film was laminated with a polarizer and a pressure of the back side cellulose ester film 20-30 N / cm ^2, the conveyance speed was pasted at approximately 2m / min.

  Step 5: Samples obtained by bonding the polarizer, the retardation film, and the backside cellulose ester film prepared in Step 4 in a dryer at 80 ° C. were dried for 2 minutes to prepare circularly polarizing plates-1 to 19.

  In addition, a stretched film (A) described in Example 1 of JP-A-2007-94007 was prepared as a comparative sample, and a circularly polarizing plate-20 having a vertically aligned liquid crystal layer coated thereon was prepared. The stretched film (A) was bonded to a polarizer using a urethane adhesive.

(Production of organic EL element)
An organic EL device was produced according to the method described in JP-A-2003-332068.

On one side of the glass substrate, an anode made of an ITO transparent film having a thickness of 120 nm was formed from an ITO ceramic target (In ₂ O ₃ : SnO ₂ = 90% by mass: 10% by mass) using a DC sputtering method. Thereafter, ultrasonic cleaning was performed, followed by cleaning with an ultraviolet ozone method.

Next, N, N′-diphenyl-N, N′-bis- (3-methylphenyl)-[1,1′-biphenyl] placed on a molybdenum boat in a resistance heating vacuum deposition apparatus on the ITO surface. The pressure inside the vacuum chamber was reduced to 1 × 10 ⁻⁴ Pa through -4,4′-diamine (TPD) and tris (8-quinolinol) aluminum (Alq) placed on another molybdenum processing boat. Was heated to 220 ° C. to form a hole transport layer composed of a TPD film having a thickness of 60 nm, and then Alq was heated to 275 ° C. to form an Alq film having a thickness of 60 nm.

Then, the vacuum chamber is reduced to 2 × 10 ⁻⁴ Pa by magnesium, which is arranged on a molybdenum boat, and silver, which is placed on another molybdenum processing boat. Then, a cathode having a thickness of 100 nm made of an Mg.Ag alloy (Mg / Ag = 9/1) was formed to produce an organic EL element 1 that emits green light (main wavelength: 513 nm).

The produced organic EL device had a light emission area of 2 cm × 3 cm. The front luminance when a DC voltage of 6 V was applied to the organic EL element 1 was 1200 cd / m ² .

  The circularly polarizing plates 1 to 20 of the present invention were attached to a glass substrate of an organic EL element with an acrylic adhesive as a sample.

  The circularly polarizing plate was bonded so that the retardation film of the present invention was positioned between the glass substrate of the organic EL element 1 and the linear polarizing plate.

<Evaluation of angle dependence of blackness for preventing external light reflection>
The organic EL device with the circularly polarizing plate attached is stored in a room at 23 ° C. and 55% RH for 48 hours (state 1), then no voltage is applied and no light is emitted, and it is placed in an environment with an illuminance of about 100 lx. The blackness level of the reflected color was visually evaluated from the direction of 45 degrees obliquely from the front, and the difference was compared.

  In addition, the comparison result was evaluated according to which of the following states it corresponds.

◎: No difference in external light reflection between the front and the squint ○: A slight difference in external light reflection between the front and the squint, but no concern △: There is a difference in external light reflection between the front and squint Difficult state of concern ×: State of extreme concern due to the difference in external light reflection between the front and perspective

  From Table 4, the sample of the present invention has good blackness of external light reflection.

It is the schematic of a goniophotometer. It is one schematic of the extending | stretching apparatus of this invention (stretching apparatus 3). It is one schematic of the extending | stretching apparatus of this invention (stretching apparatus 2). It is one schematic of the extending | stretching apparatus of this invention (stretching apparatus 1). It is one of the embodiments of the circularly polarizing plate of the present invention. It is one of the embodiments of the circularly polarizing plate of the present invention. It is one of the embodiments of the circularly polarizing plate of the present invention. It is the schematic of the embodiment of the organic EL element of this invention. It is the schematic of the melt casting film forming apparatus of this invention.

Explanation of symbols

G1 Light source lamp G2 Spectrometer G3 Sample stage (stage)
G5 Light-receiving part G6 Sample holding spring G7 Angle indexing rotary table θ Angle formed by the normal direction of the light source and the direction connecting the sample observation point and the integrating sphere 1 Stretching device 2 Film 3 Film supply device 4 Longitudinal stretching device 5 Intermediate Conveying device 6 Longitudinal stretching step 7 Oblique stretching device 8 Oblique stretching heating device 9 Oblique stretching step 10 Winding device 11 Raw material reel 12 Reference roll 13 Nip roll 14 Hot air duct 15 Ratio roll 16 Nip roll 17 Stretch chain 18 Hot air duct 19 Tension roll 20 Winding device E1 Direction parallel to transport direction (film forming direction) E2 Direction inclined by angle α with respect to transport direction (film forming direction) 101 Film 102 Preheating zone 103 Heating and stretching zone 104 Cooling zone 105 Stretched film 106,107 Screw 161 Flight 171 108,181 109,191 clip belt A transport direction (film forming direction)
DESCRIPTION OF SYMBOLS 31 Film 32 Chain 33 Clip 300 Organic EL element 301 Absorption-type linear polarizer 302 Retardation film of this invention 303 Circular polarizing element of this invention 304 Transparent substrate 305 Anode 306 Cathode 307 Light emitting layer I1 Vertical incident external light I2 Oblique incident external light 401 Extruder 402 Filter 403 Static mixer 404 Die (including thickness adjusting means)
405 Touch roll 406 First cooling roll 407 Second cooling roll 408 Peeling roll 409 Dancer roll 410 Stretcher 411 Slitter 412 Thickness measuring means 413 Embossing ring and back roll 414 Winder 415 Rolled film

Claims (4)

  Measurement of scattered light intensity of a film having a slow axis of 45 ± 5 ° with respect to the longitudinal direction and an incident light of 90 ° in the scattered light profile of a goniophotometer, and scattered light at a position of 130 ° from the light source In the case of measuring the intensity, the difference in scattered light intensity between the case where the film slow axis is horizontally installed on the sample stage and the case where the film is vertically installed is 0.05 or less. Retardation film.   The retardation film is an acrylic polymer and at least one ester compound in which at least one of a pyranose structure or furanose structure is 1 to 12 and all or part of the OH groups of the structure are esterified. The roll retardation film according to claim 1, which is a cellulose ester film to be contained.   A circularly polarizing plate comprising a polarizer and the retardation film according to claim 1.   It is a manufacturing method of the roll-shaped retardation film of Claim 1 or 2, Comprising: It has the process of extending | stretching to an inclination direction with respect to a elongate direction, or controlling shrinkage | contraction, The roll-shaped position characterized by the above-mentioned. A method for producing a phase difference film.

Images