JP4531369B2 - Method for producing cellulose acylate film and cellulose acylate film - Google Patents

Description

  The present invention relates to a method for producing a cellulose acylate film useful for a liquid crystal image display device and a silver halide photographic light-sensitive material, and a cellulose acylate film obtained by the method.

  Cellulose acylate film used as a substrate for silver halide photographic light-sensitive materials and liquid crystal image display devices is prepared by dissolving cellulose acylate in a chlorinated organic solvent such as dichloromethane to prepare a dope. It is cast on a casting support and dried to form a film. Dichloromethane has a low boiling point (boiling point: about 40 ° C.) and has an advantage that it is easy to dry, so far, it has been suitably used as an organic solvent in cellulose acylate film formation.

  Low boiling point chlorinated organic solvents are required to be handled in sealed facilities from the viewpoint of environmental conservation in recent years. For example, a thorough closed system prevents leakage from the system, and at the same time, if a leak occurs, install a gas absorption tower before releasing it to the outside air, adsorb the organic solvent, and treat it before discharging it to the outside air. Organic solvents are hardly discharged by burning with thermal power or decomposing chlorinated organic solvents with an electron beam. However, preventing complete discharge of chlorinated organic solvents is difficult and requires further research.

  On the other hand, recently, search for an organic solvent in place of dichloromethane, which has been preferably used as a chlorinated organic solvent in a cellulose acylate film forming process, has been conducted. For example, organic solvents having solubility in cellulose triester include acetone (boiling point 56 ° C.), methyl acetate (boiling point 56 ° C.), tetrahydrofuran (boiling point 65 ° C.), 1,3-dioxolane (boiling point 75 ° C.), 1, 4-dioxane (boiling point 101 ° C.) and the like are known. Among these, in particular, methyl acetate is used as an organic solvent to replace dichloromethane because it has excellent solubility and film-forming properties.

Several methods for producing a cellulose acylate film using methyl acetate have been known so far (Patent Documents 1 to 3). The methods described in these patent documents mainly improve the solubility of the polymer, and can improve the continuous film-forming property for a long time, the temporal stability of the dope, and the stripping property from the band. However, in the method described in the above-mentioned patent document, when film formation is performed at high speed and wide width (especially in the case where the width exceeds 1.4 m at a speed of 50 m / min or more), surface failure or retardation unevenness, There was a drawback that optical axis deviation was likely to occur.
Accordingly, it has long been desired to develop a method for producing a cellulose acylate film that does not have the above-described drawbacks.
JP 2002-192541 A (Claims) JP 2002-160242 A (Claims) JP 2003-55476 A (Claims)

  The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to make cellulose acylate that hardly causes optical unevenness such as surface failure, retardation unevenness, and optical axis deviation even when cast at high speed and wide width. It is in providing the film forming method of a rate film. Another object of the present invention is to provide a cellulose acylate film obtained by the film forming method.

  The present inventor has found that the disadvantage in the film forming process of cellulose acylate film is mainly stretched when a film having a high residual solvent concentration immediately after casting is conveyed at a high tension necessary for high speed film formation, and a wide film. In this case, it was found that it was easy to receive the drying air at the time of film formation drying, which caused the film to flutter during conveyance, and that nonuniform force was applied to the film. As a result of intensive studies on these causes, the present inventor has found a method capable of improving the above-mentioned drawbacks, and has completed the present invention.

That is, the object of the present invention is achieved by the following method for producing a cellulose acylate film.
(1) A method for forming a cellulose acylate film, comprising a step of casting a dope prepared by dissolving cellulose acylate with an organic solvent on a casting support from a casting die and drying to form a cellulose acylate film. And adjusting the elastic modulus of the cellulose acylate film in the drying step to be 6 to 12 MPa when the residual solvent concentration is 100% by mass, and 10 to 20 MPa when the residual solvent concentration is 50% by mass , and The cellulose acylate is adjusted so that the surface temperature on the casting support side of the cellulose acylate film in the drying step is 3 to 30 ° C. higher than the surface temperature of the cellulose acylate film on the side opposite to the casting support. A method for forming a rate film.
(2) A method for forming a cellulose acylate film, which comprises a step of casting a dope prepared by dissolving cellulose acylate with an organic solvent on a casting support from a casting die and drying to form a cellulose acylate film. The strength of the X-ray diffraction spectrum (hereinafter referred to as “XD”) of the cellulose acylate film having a residual solvent concentration of 300% by mass in the drying step by CuKα ray is 200 to 1500 cps, and the peak top 2θ of XD is 7 to 8 °. (1) The method for producing a cellulose acylate film according to (1) .
(3) The XD strength of the cellulose acylate film having a residual solvent concentration of 20% by mass in the drying step is 100 to 3000 cps greater than the XD strength of the cellulose acylate film having a residual solvent concentration of 300% by mass, and the residual solvent concentration is 20% by mass. The 2D of the XD peak top of the cellulose acylate film is adjusted to be 0.1 to 2 ° larger than the 2θ of the XD peak top of the cellulose acylate film having a residual solvent concentration of 300 mass%. A method for producing a cellulose acylate film.
(4) A method for forming a cellulose acylate film, which comprises a step of casting a dope prepared by dissolving cellulose acylate with an organic solvent on a casting support from a casting die and drying to form a cellulose acylate film. The VV scattering intensity of the cellulose acylate film having a residual solvent concentration of 300 to 45% by mass in the drying step is adjusted to 5 × 10 ^{−3 to} 5 × 10 ⁻¹ (1) to (3) The method for producing a cellulose acylate film according to any one of (3) .
(5) The cellulose acylate according to (4), wherein the HV scattering intensity of the cellulose acylate film having a residual solvent concentration of 300 to 45% by mass in the drying step is adjusted to 4 × 10 ⁻⁵ to 4 × 10 ^−3. A method for forming a film.
(6) A method for producing a cellulose acylate film, which comprises a step of casting a dope prepared by dissolving cellulose acylate with an organic solvent on a casting support from a casting die and drying to form a cellulose acylate film. In the drying step, the maximum value of the attenuation rate Δ obtained by the shaking method of the cellulose acylate film having a residual solvent concentration of 350 to 70% by mass is adjusted to 0.05 to 0.5 ( A method for producing a cellulose acylate film according to any one of 1) to (5) .
(7) A method for forming a cellulose acylate film comprising a step of casting a dope prepared by dissolving cellulose acylate with an organic solvent on a casting support from a casting die and drying to form a cellulose acylate film. a is a peak appearing at 1030～1070Cm ^-1 in infrared absorption spectroscopy in the drying step, at 1045～1050Cm ^-1 when dry start a peak top half width 46～54Cm ^-1, and the residue from the drying start solvent the peak top until a concentration of 20% by weight is shifted to range of from 0.5 to 5 cm ^-1 wave number side lower, and the half width and adjusting to increase 0.5 to 10 cm ^-1 ( A method for producing a cellulose acylate film according to any one of 1) to (6) .
(8) the peak appearing in 1740～1760Cm ^-1 in infrared absorption spectroscopy in the drying step, at 1743～1749Cm ^-1 when dry start a peak top half width 28～38Cm ^-1, and the residue from the drying start solvent (7) The peak top is adjusted to shift to 0.5-5 cm ⁻¹ low wavenumber side up to a concentration of 20% by mass and the half width increases by 0.1-5 cm ⁻¹ . A method for producing a cellulose acylate film.
(9) A method for forming a cellulose acylate film, which comprises a step of casting a dope prepared by dissolving cellulose acylate with an organic solvent on a casting support from a casting die and drying to form a cellulose acylate film. The film formation of a cellulose acylate film according to any one of (1) to (8), wherein the viscosity of the dope is reduced by 1 to 40% by adding a poor solvent to the dope. Method.
(10) to one of the using alcohol having 1 to 7 carbon atoms as a poor solvent, and 0.5 to 10 wt% with respect to dope the total amount the amount of the poor solvent (1 to 9) The film forming method described.
( 11 ) The cellulose acylate film according to any one of (1) to (10), wherein the temperature of the casting support is adjusted to 1 to 30 ° C. between the casting part and the stripping part. Film forming method.
( 12 ) The method for producing a cellulose acylate film according to any one of (1) to (11), wherein a viscosity of the dope is reduced by 1 to 40% by adding a poor solvent to the dope.
( 13 ) The method for producing a cellulose acylate film according to any one of ( 1 ) to ( 12 ), wherein drying in the drying step is performed within a temperature fluctuation range of 3 to 20 ° C.
( 14 ) The residual solvent in the cellulose acylate film is dried at a rate of 7.5 to 45 mass% per minute until the residual solvent concentration of the cellulose acylate film becomes 200 mass% to 30 mass% ( 1 ) To ( 13 ) A method for producing a cellulose acylate film according to any one of the above.
( 15 ) The cellulose acylate according to any one of (1) to ( 14 ), wherein a cellulose acylate having a degree of substitution with respect to a hydroxyl group of cellulose satisfying the following formulas (I) to (III) is used as the cellulose acylate. A method for forming a film.
(I) 2.6 ≦ SA + SB ≦ 3.0
(II) 1.5 ≦ SA ≦ 3.0
(III) 0 ≦ SB ≦ 0.8
In the formulas (I) to (III), SA and SB represent the total substitution degree of the hydroxyl group of cellulose, SA represents the substitution degree of the acetyl group, and SB represents the substitution degree of the acyl group having 3 to 22 carbon atoms. Represents.
( 16 ) As the organic solvent, at least one solvent selected from non-chlorine organic solvents ethers having 3 to 12 carbon atoms, ketones having 3 to 12 carbon atoms, and esters having 3 to 12 carbon atoms. The method for producing a cellulose acylate film according to any one of (1) to ( 15 ).
( 17 ) A cellulose acylate film obtained by the method for producing a cellulose acylate film according to any one of (1) to ( 16 ).
( 18 ) A polarizing plate comprising at least one layer of the cellulose acylate film according to ( 17 ) laminated on a polarizing layer.
( 19 ) The polarizing plate according to ( 18 ), wherein the polarizing layer is tenter-stretched with an absorption axis substantially inclined by 45 °.
( 20 ) An optical compensation film for a liquid crystal display panel using the cellulose acylate film according to ( 17 ) as a substrate.
( 21 ) An antireflection film using the cellulose acylate film according to ( 17 ) as a substrate.
( 22 ) A silver halide photographic photosensitive film using the cellulose acylate film described in ( 17 ) as a substrate.

  INDUSTRIAL APPLICABILITY According to the present invention, a cellulose acylate film forming method and a cellulose acylate film that hardly cause optical irregularities such as planar defects, retardation unevenness, and optical axis misalignment even when cast at high speed and wide width are provided. be able to.

  Hereinafter, the method for producing a cellulose acylate film and the cellulose acylate of the present invention will be described in detail. In the present specification, “to” is used as a meaning including numerical values described before and after the lower limit value and the upper limit value.

The film forming method of the present invention comprises a step of preparing a dope by dissolving cellulose acylate with an organic solvent, a step of casting the dope on a casting support, and drying the cast cellulose acylate film. Process. The casting method in the casting process of the present invention is a method of casting on a cooled drum, gelling by cooling from 15 ° C. to −100 ° C., and then peeling and drying (drum casting) and There is a method (band casting) in which the film is cast on a band at room temperature (15 to 50 ° C.), dried and stripped (band casting), and any method is included in the film forming method of the present invention.
The film forming method of the present invention essentially includes the following first and seventh aspects in the drying step, and may have second to sixth aspects . Each aspect will be described below.

<First aspect>
In the first aspect of the present invention, the elastic modulus of the cellulose acylate film in the drying step is adjusted to be 6 to 12 MPa when the residual solvent concentration is 100% by mass, and 10 to 20 MPa when the residual solvent concentration is 50% by mass. To do.
The cellulose acylate film immediately after being peeled off from the casting support contains a large amount of residual solvent. For this reason, in the subsequent drying process, there is a drawback that optical unevenness is likely to occur during stretching by tension or drying air. In the first aspect, in this drying process, in order to increase the gel strength of the cellulose acylate film, the elastic modulus of the cellulose acylate film when the residual solvent concentration is 100% by mass is 6 to 12 MPa, preferably 6 to The pressure is adjusted to 11 MPa, more preferably 6 to 10 MPa. Further, the elastic modulus of the cellulose acylate film when the residual solvent concentration is 50% by mass is adjusted to a range of 10 to 20 MPa, preferably 10 to 18 MPa, and more preferably 10 to 16 MPa.

The preferable elastic modulus of the cellulose acylate in the drying step is that a poor solvent (preferably an alcohol) is added to the dope in an amount of 0.5 to 10% by mass with respect to 100 parts by mass of the cellulose acylate, resulting in a viscosity reduction of 1 to 40%. The temperature of the blown air is 30 to 80 ° C. as the drying condition of the support, the wind speed is 4 to 20 m / second, the surface temperature of the support is 20 to 70 ° C., the support By making the temperature difference between the front and back of 3-30 ° C., making the temperature difference between the stripped part and the casting part 1-30 ° C., and making the drying temperature after stripping 7.5-45 ° C. Achieved.
In the present specification, the “residual solvent concentration” refers to the content of the organic solvent remaining in the cellulose acylate film formed by casting. The cellulose acylate film after drying for a predetermined time ( It is calculated | required by the percentage [(B / A) x100 (%)] with the mass B of the volatilized organic solvent with respect to the mass A of a cellulose acylate + organic solvent. In addition, the elastic modulus is obtained by measuring the film thickness and width of the cellulose acylate film immediately after peeling off from the casting support in advance to obtain the cross-sectional area C, and measuring the tensile force D under a predetermined condition. / C.

<Second aspect>
In the second aspect of the present invention, the X-ray diffraction spectrum (XD) intensity of the cellulose acylate film having a residual solvent concentration of 300% by mass in the drying step is adjusted to 200 to 1500 cps by CuKα rays, and the top peak of the XD Adjust 2θ to 7-8 °.
Here, “XD intensity” means the height of the peak from the baseline when XD measurement is performed. The “top peak” refers to the 2θ position of the maximum peak that appears in the XD measurement.

  In the drying process, the XD strength of the cellulose acylate film when the residual solvent concentration is 300% by mass was conventionally 100 cps or less. However, if the XD strength is 100 cps or less, crystals in the film in the drying process Insufficient growth. Therefore, in the second aspect of the present invention, the XD intensity is adjusted in the range of 200 to 1500 cps, preferably 250 to 1200 cps, more preferably 300 to 1000 cps in the drying step. If the XD strength is 200 cps or more, crystallization can be promoted in the film at the beginning of drying in the film forming process, and the strength of the film can be increased.

  Further, the position of 2θ of the top peak by XD indicates the crystal lattice spacing in the cellulose acylate film, and the smaller this means the larger the crystal lattice spacing. In the conventional film forming method, 2θ at the peak top was 8.1 to 8.5 °, but in the second embodiment, this is 7 to 8 °, preferably 7.2 to 7.8 °, more preferably It is characterized in that it is adjusted to be as small as 7.3 to 7.7 ° and the lattice spacing of the crystal is increased.

  In the second aspect of the present invention, as described above, there are many crystals having a large lattice spacing in the initial stage of drying. A large lattice spacing means that the crystal structure is loose, and it is assumed that the crystal structure is weak. At first glance, the film strength seems to decrease. However, in the case of a film with a large lattice spacing and a loose crystal structure, there is a half-finished film in which only a part of the molecule is incorporated into the crystal, which crosslinks between the crystals to form a network, so the cellulose acylate film The strength of the film increases, and the more such crystals and networks, the higher the film strength.

  In the second aspect of the present invention, the XD strength of the cellulose acylate film having a residual solvent concentration of 20% by mass is 100 to 3000 cps, preferably higher than the XD strength of the cellulose acylate film having a residual solvent concentration of 300% by mass. It is preferable to adjust to 200 to 2500 cps, more preferably 300 to 2000 cps. If the XD strength of the cellulose acylate film when the residual solvent concentration is 20% by mass is 100 to 3000 cps greater than the XD strength of the cellulose acylate film when the residual solvent concentration is 300% by mass, as the drying proceeds. The amount of crystals in the film increases and the film strength can be further improved.

  Furthermore, in the second aspect of the present invention, the XD peak top 2θ of the cellulose acylate film having a residual solvent concentration of 20% by mass is more than the 2D of the XD peak top of the cellulose acylate film having a residual solvent concentration of 300% by mass. It is preferable to adjust so as to increase by 0.1 to 2 °, preferably 0.2 to 1.5 °, more preferably 0.2 to 1 °. Thus, the fact that the 2θ at the peak top increases with the progress of drying means that the lattice spacing of the crystal decreases as the drying proceeds. A network is formed between the crystals in the early stage of drying, and then the lattice spacing of the crystals is reduced, so that crystals with higher density are formed and the film strength can be increased.

In the drying step, the adjustment of the XD intensity of the cellulose acylate film and the peak top 2θ value when the residual solvent concentration is 300% by mass and 20% by mass is the substitution degree of cellulose acylate, the viscosity of the dope described later, It can be performed by appropriately adjusting the temperature of the casting support and the drying temperature of the cell source acylate film. The XD intensity and the XD peak top can be measured using a commercially available CuKα ray X-ray diffractometer (for example, Rigaku Corporation RINT-ULTIMA).
The preferable value of XD intensity and 2θ in the drying step is achieved by setting the temperature variation to 3 to 20 ° C. as the drying condition of the support.

<Third Aspect>
In the third aspect of the present invention, the VV scattering intensity of the cellulose acylate film having a residual solvent concentration of 300 to 45% by mass in the drying step is 5 × 10 ^{−3 to} 5 × 10 ⁻¹ , preferably 7 ×. It is adjusted to 10 ⁻³ to 1 × 10 ⁻¹ , more preferably 9 × 10 ^{−3 to} 7 × 10 ⁻² . Furthermore, in the third aspect of the present invention, the HV scattering intensity of the cellulose acylate film is 4 × 10 ⁻⁵ to 4 × 10 ⁻³ , preferably 5 × 10 ⁻⁵ to 2 at the residual solvent concentration in the above range. × 10 ⁻³ , more preferably 5 × 10 ⁻⁵ to 1 × 10 ⁻³ .

  Having the above scattering intensity while the residual solvent concentration changes from 300% by mass to 45% by mass (the initial stage of drying) means that “density fluctuation” occurs in the cellulose acylate film. That is, it is considered that there is a portion where the concentration of the cellulose acylate solution is high in the cellulose acylate film, and the crystallization is promoted in this portion. Such “concentration fluctuation” is effective in the early stage of drying because it promotes the formation of crystal nuclei that are the basis of crystals.

  “HV scattering intensity” and “VV scattering intensity” in the third aspect are set in the order of the light source, the polarizer, the sample film, the polarizer, and the detector (CCD camera), and the light is placed on the plane of the sample film. It is the scattering intensity when incident perpendicularly and the intensity of scattered light is measured by a detector. The scattering intensity when the detector-side polarizer is arranged at right angles to the light source-side polarizer is HV scattering, and the scattering intensity when these are arranged in parallel is VV scattering.

  Scattered light is measured as a two-dimensional image on a plane arranged perpendicular to the incident light. For this reason, for each scattering angle, the incident light is integrated over the entire 360 ° circumference, and the average value is used as the scattering intensity at the scattering angle. In the present invention, the measurement was performed over a scattering angle of 2 to 20 °, and the height of the signal indicating the maximum intensity among these was defined as the scattering intensity.

The above-mentioned “concentration fluctuation” is achieved by adjusting the solvent for dissolving the cellulose acylate and the drying conditions.
(1) Solvent adjustment The organic solvent for dissolving cellulose acylate in the film forming method of the present invention may be a chlorine-based or non-chlorine-based organic solvent, but the viewpoint of facilitating the occurrence of “concentration fluctuation”. Is preferably a non-chlorine organic solvent. As the non-chlorine organic solvent, it is preferable to use at least one solvent selected from ethers having 3 to 12 carbon atoms, ketones having 3 to 12 carbon atoms, and esters having 3 to 12 carbon atoms. Conventionally, dichloromethane is generally used to dissolve cellulose acylate. However, in the film forming method of the present invention, the above-mentioned solvent is used to easily generate “concentration fluctuation”. -V scattering and V-V scattering can be increased, crystallization can be promoted, and film strength can be increased. The solvent composition will be described in detail later.

(2) Adjustment of drying conditions Since the above-mentioned "concentration fluctuation" is a kind of phase separation, it can be easily generated by giving a change in temperature to trigger phase separation. This phase separation is an LCST type, and phase separation is performed at a high temperature. The temperature fluctuation range is suitably 3 to 20 ° C, preferably 4 to 18 ° C, and more preferably 5 to 16 ° C. After exposure to a high temperature, it is preferable to drop the temperature to the original temperature immediately (within 1 minute). This is because the solvent volatilizes too quickly at a high temperature, and the solvent volatilizes before the crystal grows. The preferable temperature before the fluctuation is 25 to 50 ° C, and preferably 30 to 45 ° C. For such temperature fluctuation to the high temperature side, it is preferable to use the non-chlorinated solvent. This is because the latent heat of vaporization of the chlorinated solvent is large, the temperature is likely to decrease during the drying process, and it is difficult to cause a temperature fluctuation to the high temperature side. Such temperature fluctuation is achieved by providing a wind outlet at a desired temperature in a drying zone adjusted to a constant temperature, and locally heating it using a spot heat source such as an IR heater or halogen heater. it can. The “concentration fluctuation” is preferably applied at the initial stage of drying, and is preferably performed on the casting support (before peeling) after casting.

<Fourth aspect>
In the fourth aspect of the present invention, the attenuation rate Δ determined by the shaking method in the drying step is a residual solvent concentration of 3
The maximum value is between 50 and 70% by mass, and the maximum value is adjusted in the range of 0.05 to 0.5.
In order to increase the strength of the cellulose acylate film, it is preferable to increase the density of the amorphous part of the film. For this purpose, the maximum value of the attenuation rate Δ in the shaking method is adjusted to 0.05 to 0.5, preferably 0.07 to 0.45, more preferably 0.1 to 0.4. Is preferred. When the attenuation factor Δ is in the range of 0.05 to 0.5, optical unevenness (Re and Rth unevenness, optical axis misalignment) and surface defects (wrinkles) can be suppressed, and failure can be prevented. .

The shaking method here refers to passing a ridge (cylinder) on a film formed by casting a dope 2 in which cellulose acylate is dissolved in an organic solvent on a casting support 1, and swinging from both ends downward. The pendulum 3 is formed by hanging a pendulum weight, the weight of the pendulum 3 is lifted to a certain height, and then released to vibrate (see FIG. 1), and the dope is measured by measuring the change with time of the amplitude. This is a method for measuring the viscosity of The attenuation rate Δ is, for example, {a (n + 1) −a (n)} / a (n) where the amplitude at the nth time is a (n) and the amplitude at the (n + 1) th time is a (n + 1). Can be sought. It means that the larger this attenuation Δ (that is, closer to 1), the larger and softer the viscosity is, and the smaller (that is, closer to 0) the smaller and harder the viscosity is.
The attenuation factor Δ by the shaking method can be obtained by using a commercially available pendulum type elasticity measuring instrument. The attenuation rate by a preferable shaking method can be achieved by setting the blowing air velocity to 4 to 20 m / sec under dry conditions.

<Fifth aspect>
In the fifth aspect of the present invention, the peak top shift width and half of the infrared absorption spectrum in a specific range measured by infrared absorption spectroscopy of the cellulose acylate film at the start of drying and until reaching a predetermined residual solvent concentration. By adjusting the amount of increase in the value range, the strength of the amorphous part can be improved.
That is, in the fifth embodiment, in the drying process, the peak appearing at 1030～1070Cm ^-1 by infrared absorption spectroscopy, the start of drying (drying 0 min) in the range of 1045～1050Cm ^-1 half width 46～54Cm ^{- 1 and} the peak top shifts to 0.5-5 cm ⁻¹ low wavenumber side from the start of drying until the residual solvent concentration of the cellulose acylate film reaches 20% by mass, and the half The value range is adjusted to increase by 0.5 to 10 cm ⁻¹ .

  During the drying process, changes in the peak top and half-value width of the infrared absorption spectrum show that the organic solvent volatilizes from the state of a lot of organic solvent in the initial stage of drying (the state in which the cellulose acylate is surrounded by the organic solvent). Means that it has changed into a state of contact and entanglement. Therefore, as the amount of change between the peak top and the half width increases, the entanglement between the cellulose acylates increases and the strength of the amorphous part increases.

The peak appearing in the range of 1030 to 1070 cm ⁻¹ by the infrared absorption spectrum is a peak derived from a glucopyranose ring and an acetyl group resulting from symmetrical stretching of the C—O bond of cellulose acylate. The peak of the drying start showed a peak top in the range of 1045～1050Cm ^-1, the half width of the peak top is 46～54Cm ^-1, preferably 47～53Cm ^-1, more preferably 47-52 cm ^-1 . In addition, the peak top from the start of drying until the residual solvent concentration of the cellulose acylate film reaches 20% by mass is 0.5 to 5 cm ⁻¹ , preferably 0.7 to 4.5 cm ⁻¹ , and more preferably. Shift to 1-4 cm ^-1 low wavenumber side. Further, the half width of the peak top is increased by 0.5 to 10 cm ⁻¹ , preferably ¹ to 9 cm ⁻¹ , more preferably 1.5 to 8 cm ⁻¹ . A peak top shift of 0.5 to 10 cm ⁻¹ and an increase in half width of 0.5 to 10 cm ⁻¹ are preferable because optical unevenness (Re, Rth unevenness) can be reduced.

In the fifth aspect, in the drying process, the peak appearing at 1740 to 1760 cm ⁻¹ by infrared spectroscopy shows the peak top at 1743 to 1749 cm ⁻¹ at the start of drying, and the half width is 28 to 38 cm ⁻¹ . Furthermore, from the start of drying until the residual solvent concentration reaches 20% by mass, the peak top shifts to the low wave number side by 0.5 to 5 cm ⁻¹ and the half width increases by 0.1 to 5 cm ^−1. It is preferable to adjust to.

The peak appearing in the range of 1740 to 1760 cm ^{−1 in} the infrared absorption spectrum is a peak derived from an acetyl group resulting from the stretching of C═O bond of cellulose acylate. FWHM of dry starting peak top is 28～38Cm ^-1, is preferably 28.5～36Cm ^-1, further preferably 29~35cm ^-1. Further, the peak top range of from 0.5 to 5 cm ^-1 in the drying start until the residual solvent concentration of 20 wt%, preferably 1～4.5Cm ^-1, more preferably 1.5～4Cm ^-1 low wavenumber It is preferable to shift to the side. Furthermore, the half width of the peak top is 0.1 to 5 cm ⁻¹ , preferably 0.2 to 4 cm ⁻¹ , more preferably 0.3 to 3 cm from the start of drying until the residual solvent concentration reaches 20% by mass. It is preferable to increase by ^-1 .
The peak position and the half width at the preferred infrared absorption method can be achieved by setting the blowing air velocity to 4 to 20 m / sec under dry conditions.

<Sixth aspect and seventh aspect>
In order to facilitate the entanglement between the cellulose acylate crystals from the beginning of drying and to increase the film strength, it can be achieved by adjusting the following materials and adjusting the drying conditions.
That is, in the sixth aspect, the viscosity of the dope is reduced by 1 to 40% by adding a poor solvent to the dope. In the seventh aspect, the surface temperature on the casting support side of the cellulose acylate film in the drying step is 3 to 30 ° C. higher than the surface temperature of the cellulose acylate film on the side opposite to the casting support. adjust. The seventh aspect is preferably adjusted so that the temperature of the casting support rises from 1 to 30 ° C. between the casting part and the stripping part.

(1) Preparation of material (a) Cellulose acylate As the cellulose acylate used in the present invention, it is preferable to use cellulose acylate having a high degree of substitution with respect to the hydroxyl group of cellulose. That is, in the film forming method of the present invention, by using cellulose acylate having a high degree of substitution, a hydrophobic bond between acetyl groups can be imparted as a driving force during the entanglement of cellulose acylate crystals. Details of such cellulose acylate will be described later.

(B) Adjustment of viscosity of dope Between dissolution of cellulose acylate and casting, the viscosity of dope (solution in which cellulose acylate is dissolved in organic solvent) is 1 to 40%, preferably 3 to 35%, More preferably, it is preferably reduced by 5 to 30%. The decrease in the viscosity means that the cellulose acylate that has spread in the dope is contracted. As a result, in the subsequent drying step, the solvent taken into the cellulose acylate can be quickly driven out, and drying can be promoted to form a hard film. However, since the direction in which the viscosity is lowered in this way is to reduce the solubility of cellulose acylate, it is preferably carried out after completely dissolving the cellulose acylate.

  The reduction in viscosity is achieved by adding a poor solvent in the dope. A preferred poor solvent includes alcohol. Preferably it is a C1-C7 alcohol, More preferably, it is a C1-C5 alcohol. Furthermore, it is preferable to use a monovalent alcohol from the viewpoint of volatility. Specifically, methanol, ethanol, propanol and butanol are preferably used. Of these, butanol is particularly preferred.

  The addition amount of the poor solvent can be appropriately determined within a range where the viscosity of the dope is reduced by 1 to 40%, preferably 0.5 to 10% by mass, preferably 1 to 7% by mass, further based on the total amount of the dope. Preferably it is 1-5 mass%. The method of adding the poor solvent to the dope is not particularly limited. For example, the method of adding to the tank after dissolution and stirring with a blade, or stirring using a screw in the pipe from the dissolution tank to the casting part The method of adding it, etc. is mentioned.

(2) Adjustment of drying conditions (a) Adjustment of temperature difference between front and back surfaces during drying By slowing the drying speed at the initial stage of drying, entanglement between cellulose acylate molecules is promoted and the strength of the amorphous part is increased. Can be promoted. Furthermore, by slowing down the drying rate, the above-mentioned “concentration fluctuation” can be easily generated, the HV scattering intensity and the VV scattering intensity are increased, crystallization is promoted, and the film strength is increased. You can also
In order to realize such a slow drying rate, it is preferable to form a skin layer (skinning) on the film surface (air interface). That is, the solvent on the casting support side (deep in the thickness direction) diffuses to the surface and volatilizes from there, but if a skin layer is formed on the film surface, the volatilization slows down, and the same effect as above is obtained. And the number of entanglements between cellulose acylates can be increased. Such a skin layer can be formed by the following method.

(B) Blow high-speed wind.
It is preferable to blow high speed air on the cellulose acylate film surface to dry the film surface quickly. The preferred wind speed is preferably 4 to 20 m / sec, more preferably 5 to 16 m / sec, and further preferably 6 to 12 m / sec. The temperature of the drying air at this time is preferably 25 to 100 ° C, more preferably 30 to 80 ° C, and further preferably 35 to 70 ° C. The humidity of the blowing air is preferably 0 to 70% RH, and more preferably 0 to 50% RH from the viewpoint of preventing condensation.

(B) A temperature difference is given to the back surface.
The temperature of the cellulose acylate film surface (back surface) on the casting support side is 3 to 30 ° C., preferably 4 to 25 ° C., more preferably from the temperature of the cellulose acylate film surface (front surface) on the side opposite to the casting support side. It is low 5~20 ℃. By imparting such a temperature difference on the back surface, diffusion of the solvent on the casting support side to the surface side can be delayed, and the occurrence of entanglement between the crystals of cellulose acylate can be further promoted. At this time, the temperature on the film surface side is preferably 20 to 70 ° C, more preferably 25 to 60 ° C, and further preferably 30 to 50 ° C.
The temperature on the surface side of the cellulose acylate can be measured using a non-contact thermometer, and the temperature on the back side of the cellulose acylate is attached to a thermocouple on the casting support. It can be measured by casting.

  When the temperature of the cellulose acylate film is raised, the temperature of the casting support is 1 to 30 ° C., preferably 2 to 25 ° C. between the casting part and the stripping part while maintaining the temperature difference between the front and back surfaces. More preferably, the temperature is raised by 3 to 20 ° C. Such a temperature increase can efficiently increase the volatilization rate of the solvent. That is, at the initial stage of forming the skin layer, the temperature is lowered, the solvent volatilization is delayed, and a firm skin layer is formed. However, since the volatilization rate is slowed and productivity is lowered as it is, the temperature in the latter half is raised to increase the drying rate. Such temperature control is performed by dividing the back surface of the casting support (the surface opposite to the surface on which the dope is cast) into several zones and blowing air cooled to a predetermined temperature, This is achieved by a method such as blowing warm air on the surface on which the dope is cast.

(B) Drying speed immediately after stripping By drying a predetermined residual solvent concentration area immediately after stripping at a predetermined speed, the cellulose acylate is effectively entangled and the strength of the amorphous part is increased. Can be made. That is, after casting, the residual solvent concentration is between 200 and 30% by mass, 7.5 to 45% by mass / min, preferably 10 to 40% by mass / min, and more preferably 15 to 35% by mass / min. It is preferred to dry the residual solvent at a rate. Conventionally, since drying was performed at a speed higher than this speed, sufficient film strength could not be obtained.However, in the present invention, only the above-mentioned region most effective for the expression of entanglement between cellulose acylates was slowly added. Since the film is dried, the film strength can be effectively improved without substantially extending the overall drying time.

  Such a drying speed is controlled by adjusting the temperature of the substrate (band, drum) to be cast while sampling the film being dried and monitoring the residual solvent by gas chromatography or the like, and the temperature of the drying air blown on the substrate. This can be achieved by adjusting the air volume.

Next, materials used in the film forming method of the present invention will be described in detail.
(Cellulose acylate)
The cellulose acylate used in the film forming method of the present invention is not particularly limited as long as the effects of the present invention are exhibited. As the cellulose acylate, only the same type of cellulose acylate may be used, or two or more different types of cellulose acylate may be mixed and used. Among them, a preferable cellulose acylate is a cellulose acylate whose degree of substitution with respect to the hydroxyl group of cellulose satisfies all the conditions of the following formulas (I) to (III).

2.6 ≦ SA + SB ≦ 3.0 (I)
1.5 ≦ SA ≦ 3.0 (II)
0 ≦ SB ≦ 0.8 (III)
Here, SA and SB in the formula represent the total degree of substitution of cellulose with respect to hydroxyl groups, SA represents the degree of substitution of acetyl groups, and SB represents the degree of substitution of acyl groups having 3 to 22 carbon atoms.

When one cellulose acylate molecule is brought into contact with another cellulose acylate molecule, it is particularly effective to mask the hydroxyl group at the 6-position which is slightly away from the glucopyranose ring and easily rotates freely. For this reason, it is more preferable that the degree of substitution satisfies the condition of the following formula (IV). Here, S6 is the sum of the substitution degrees of SA and SB at the 6-position of cellulose acylate.
0.8 ≦ S6 ≦ 1 (IV)

  Glucose units having β-1,4 bonds constituting cellulose have free hydroxyl groups at the 2nd, 3rd and 6th positions. Cellulose acylate is a polymer obtained by esterifying some or all of these hydroxyl groups with acyl groups. The degree of acyl substitution means the proportion of cellulose esterified at each of the 2-position, 3-position and 6-position (100% esterification has a degree of substitution of 1). In the present invention, the total sum of the degree of substitution of SA and SB of the hydroxyl group is preferably 2.7 to 2.96, more preferably 2.80 to 2.95. Moreover, the substitution degree of SB is 0-0.8, More preferably, it is 0-0.6. Further, 28% or more of SB is a substituent at the 6-position hydroxyl group, preferably 30% or more, more preferably 31% or more, and further preferably 32% or more is a substituent at the 6-position hydroxyl group. The total substitution degree of SA and SB at the 6-position of cellulose acylate is 0.8 or more, preferably 0.85, and particularly preferably 0.90. The degree of substitution of SA is 1.5 to 3.0, preferably 2.4 to 2.95, and more preferably 2.6 to 2.95. By using such cellulose acylate, a preferable dope having a solubility can be produced, and particularly in a non-chlorine organic solvent, a good dope can be produced.

  The acyl group (SB) of the cellulose acylate used in the present invention is not particularly limited, but is preferably an aliphatic group having 3 to 22 carbon atoms or an allyl group. For example, cellulose alkylcarbonyl ester, alkenylcarbonyl ester or aromatic carbonyl ester, aromatic alkylcarbonyl ester and the like may be mentioned, and each may further have a substituted group.

  Preferred acyl groups (SB) having 3 to 22 carbon atoms include propionyl, butanoyl, keptanoyl, hexanoyl, octanoyl, decanoyl, dodecanoyl, tridecanoyl, tetradecanoyl, hexadecanoyl, octadecanoyl, iso-butanoyl, t-butanoyl , Cyclohexanecarbonyl, oleoyl, benzoyl, naphthylcarbonyl, cinnamoyl group and the like. Of these, acyl groups (SB) such as propionyl, butanoyl, dodecanoyl, octadecanoyl, t-butanoyl, oleoyl, benzoyl, naphthylcarbonyl, and cinnamoyl are preferable.

  The basic principle of the cellulose acylate synthesis method is described in Ueda et al., Wood Chemistry, 180-190 (Kyoritsu Shuppan, 1968). A typical synthesis method is a liquid phase acetylation method using a carboxylic acid anhydride-acetic acid-sulfuric acid catalyst. Specifically, cellulose raw materials such as cotton linter and wood pulp are pretreated with an appropriate amount of acetic acid, and then put into a pre-cooled carboxylic acid mixture to be esterified to complete cellulose acylate (2nd, 3rd and 6th). The total degree of acyl substitution at the position is approximately 3.00). The carboxylated mixed liquid generally contains acetic acid as a solvent, carboxylic anhydride as an esterifying agent, and sulfuric acid as a catalyst. The carboxylic anhydride is usually used in a stoichiometric excess over the sum of the cellulose that reacts with it and the water present in the system. After the acylation reaction is completed, a neutralizing agent (for example, calcium, magnesium, iron, aluminum or zinc) is used for hydrolysis of excess carboxylic anhydride remaining in the system and neutralization of a part of the esterification catalyst. Of carbonate, acetate or oxide).

  Next, the obtained complete cellulose acylate is saponified and aged by maintaining it at 50 to 90 ° C. in the presence of a small amount of an acetylation reaction catalyst (generally, remaining sulfuric acid) to obtain a desired degree of acyl substitution and degree of polymerization. To a cellulose acylate having When the desired cellulose acylate is obtained, the catalyst remaining in the system is completely neutralized with a neutralizing agent as described above, or in water or dilute sulfuric acid without neutralization. The cellulose acylate solution is added (or water or dilute sulfuric acid is added into the cellulose acylate solution) to separate the cellulose acylate, and the cellulose acylate is obtained by washing and stabilizing treatment.

  For the synthesis of cellulose acylate having a high degree of substitution at the 6-position, methods described in JP-A-11-5851, JP-A-2002-212338, JP-A-2002-338601, etc. can be used. .

  The degree of polymerization of cellulose acylate preferably used in the present invention is a viscosity average degree of polymerization of 200 to 700, preferably 250 to 550, more preferably 250 to 400, and particularly preferably 250 to 350. The viscosity average degree of polymerization can be measured by Uda et al.'S limiting viscosity method (Kazuo Uda, Hideo Saito, Journal of Textile Science, Vol. 18, No. 1, pages 105-120, 1962). Further, it can be measured by the method described in detail in JP-A-9-95538.

  When the low molecular component is removed, the average molecular weight (degree of polymerization) increases, but the viscosity becomes lower than that of normal cellulose acylate, which is useful. Cellulose acylate having a small amount of low molecular components can be obtained by removing low molecular components from cellulose acylate synthesized by a usual method. The removal of the low molecular component can be carried out by washing the cellulose acylate with an appropriate organic solvent. In addition, when manufacturing the cellulose citrate with few low molecular components, it is preferable to adjust the sulfuric acid catalyst amount in an acetylation reaction to 0.5-25 mass parts with respect to 100 mass parts of cellulose. When the amount of the sulfuric acid catalyst is within the above range, cellulose acylate that is preferable in terms of molecular weight distribution (uniform molecular weight distribution) can be synthesized.

  The above-mentioned cellulose acylate used in the present invention has its raw material cotton and synthesis method disclosed on pages 7 to 12 of the Japan Society for Invention and Technology (public technical number 2001-1745, published on March 15, 2001, Japan Society for Invention). It is described in detail.

  In the present invention, the cellulose acylate is preferably made of cellulose acylate that substantially satisfies the above-mentioned conditions. Here, “substantially” means 55% by mass or more of the polymer component, preferably 70% by mass or more, and more preferably 80% by mass or more.

  When the cellulose acylate is used for production, the water content is preferably 2% by mass or less, more preferably 1% by mass or less, and further preferably 0.7% by mass or less. In general, cellulose acylate contains water and is known to contain 2.5 to 5% by mass of water. In the present invention, the cellulose acylate needs to be dried in order to obtain a moisture content of 2% by mass or less, but the drying method is not particularly limited as long as the intended moisture content is achieved.

  Cellulose acylate is preferably used in the form of particles in order to improve solubility. In particular, 90% by mass or more of the particles to be used preferably have a particle diameter of 0.5 to 5 mm. Moreover, it is preferable that 50 mass% or more of the particle | grains to be used have a particle diameter of 1-4 mm. The cellulose acylate particles preferably have a shape as close to a sphere as possible.

(Additive)
In the dope (cellulose acylate solution) of the present invention, various additives (for example, plasticizers, ultraviolet inhibitors, deterioration inhibitors, optical anisotropy control agents, fine particles, release agents) according to the application in the preparation process. , Infrared absorbers, surfactants, etc.). The additive may be added in any step of the dope preparation step, but is preferably added in the last step of the dope preparation step. Furthermore, there is no restriction | limiting in particular as long as the addition amount of each additive expresses the function. A plasticizer can be added, for example with the addition amount of Unexamined-Japanese-Patent No. 2001-151901, and it is made to contain by the content rate (concentration) of 0.1-25 mass% with respect to the mass of a cellulose acylate. Is preferred. Moreover, an infrared absorption dyeing agent can be added with the addition amount as described in Unexamined-Japanese-Patent No. 2001-194522, for example. Moreover, an ultraviolet absorber can be added with the addition amount as described in Unexamined-Japanese-Patent No. 2001-151901, for example. The infrared absorbent and the ultraviolet absorbent are each preferably contained at a content of 0.001 to 5% by mass with respect to the mass of cellulose acylate.

  It is preferable to use fine particles having an average particle diameter of 5 nm to 3 μm, and those made of a metal oxide or a crosslinked polymer can be used and contained at a concentration of 0.001 to 5% by mass with respect to the mass of cellulose acylate. It is preferable to make it. The release agent is preferably contained at a content of 0.0001 to 2% by mass with respect to the mass of cellulose acylate. Moreover, it is preferable to contain a deterioration inhibiting agent with the content rate of 0.0001-2 mass% with respect to the mass of a cellulose acylate. The optical anisotropy control agent can be used in an addition amount described in, for example, JP-A Nos. 2003-66230 and 2002-49128, and is 0.1 to 15% by mass with respect to the mass of cellulose acylate. It is preferable to contain by content rate. Moreover, it is preferable to use a fluorosurfactant as the surfactant, and it is preferable to contain the surfactant at a content of 0.001 to 2% by mass with respect to the mass of the cellulose acylate.

  Furthermore, these details are described in detail on pages 16 to 22 of the Japan Society for Invention and Technology (Public Technical Number 2001-1745, published on March 15, 2001, Japan Institute of Invention). Moreover, when a cellulose acylate film is formed in multiple layers, the type and amount of each layer of these additives may be different or the same. For example, it is described in Unexamined-Japanese-Patent No. 2001-151902 etc., and an additive and addition amount can be used.

(Organic solvent)
The organic solvent used in the present invention is not particularly limited, and may be a chlorinated solvent or a non-chlorinated solvent. From the viewpoint of easy expression of “concentration fluctuation”, the chlorinated solvent is not used. Is preferably used. The organic solvent may be a fresh solvent or a recovered solvent.

(1) Non-chlorine solvent The cellulose acylate of the present invention is dissolved in an organic solvent to prepare a dope. For this, a non-chlorine solvent is preferably used. A preferred non-chlorine organic solvent is a solvent selected from esters, ketones and ethers having 3 to 12 carbon atoms. The ester, ketone and ether may have a cyclic structure. A compound having two or more functional groups of esters, ketones and ethers (that is, —O—, —CO— and COO—) can also be used as the main solvent, and other functional groups such as alcoholic hydroxyl groups can be used. It may have a group. In the case of a solvent having two or more types of functional groups, the number of carbon atoms may be within the specified range of the compound having any functional group.

  Specific examples of the esters having 3 to 12 carbon atoms include ethyl formate, propyl formate, pentyl formate, methyl acetate, ethyl acetate and pentyl acetate. Specific examples of the ketone having 3 to 12 carbon atoms include acetone, methyl ethyl ketone, diethyl ketone, diisobutyl ketone, cyclopentanone, cyclohexanone and methylcyclohexanone. Specific examples of the ether having 3 to 12 carbon atoms include diisopropyl ether, dimethoxymethane, dimethoxyethane, 1,4-dioxane, 1,3-dioxolane, tetrahydrofuran, anisole and phenetole. Examples of the organic solvent having two or more kinds of functional groups include 2-ethoxyethyl acetate, 2-methoxyethanol and 2-butoxyethanol.

  Furthermore, the preferable organic solvent of the cellulose acylate of the present invention is a mixed solvent of three or more different types. In the mixed solvent, the first solvent is at least one selected from methyl acetate, ethyl acetate, methyl formate, ethyl formate, acetone, dioxolane, and dioxane, or a mixed solution thereof. The second solvent is a solvent selected from ketones having 4 to 7 carbon atoms or acetoacetate. The third solvent is selected from alcohols or hydrocarbons having 1 to 10 carbon atoms, preferably alcohols having 1 to 8 carbon atoms. In addition, when the 1st solvent is a liquid mixture of 2 or more types of solvents, there may not be the 2nd solvent.

  The first solvent is preferably methyl acetate, acetone, methyl formate, ethyl formate or a mixture thereof. The second solvent is preferably methyl ethyl ketone, cyclopentanone, cyclohexanone, methyl acetylacetate or a mixture thereof.

  The alcohol as the third solvent may be linear, branched or cyclic. Of these, saturated aliphatic hydrocarbons are preferred. The hydroxyl group of the alcohol may be any of primary, secondary and tertiary. Specific examples of the alcohol include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, t-butanol, 1-pentanol, 2-methyl-2-butanol and cyclohexanol. As the alcohol, fluorine-based alcohol is also used. Examples include 2-fluoroethanol, 2,2,2-trifluoroethanol, 2,2,3,3-tetrafluoro-1-propanol, and the like.

  Furthermore, the hydrocarbon may be linear, branched or cyclic. Either aromatic hydrocarbons or aliphatic hydrocarbons can be used. The aliphatic hydrocarbon may be saturated or unsaturated. Specific examples of the hydrocarbon include cyclohexane, hexane, benzene, toluene and xylene.

  These alcohols and hydrocarbons as the third solvent may be used alone or as a mixture of two or more, and are not particularly limited. As the third solvent, preferred specific compounds include alcohol, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, and cyclohexanol, cyclohexane, hexane, Are methanol, ethanol, 1-propanol, 2-propanol, 1-butanol.

  The above three types of mixed solvents preferably include a mixing ratio of 20 to 95% by mass of the first solvent, 2 to 60% by mass of the second solvent, and 2 to 30% by mass of the third solvent. Furthermore, it is more preferable that the first solvent is contained in a mixing ratio of 30 to 90% by mass, the second solvent is 3 to 50% by mass, and the third alcohol is contained in a mixing rate of 3 to 25% by mass. In particular, the first solvent is preferably 30 to 90% by mass, the second solvent is 3 to 30% by mass, and the third solvent is an alcohol, and preferably 3 to 15% by mass.

In addition, when a 1st solvent is a liquid mixture and it does not use a 2nd solvent, it is preferable that a 1st solvent is contained by the mixing rate of 20-90 mass% and a 3rd solvent is 5-30 mass%. More preferably, the first solvent is contained in a mixing ratio of 30 to 86% by mass, and the third solvent is contained in a mixing rate of 7 to 25% by mass.
The non-chlorine-based organic solvent used in the present invention described above is further described in pages 12 to 16 in the Japan Society for Invention and Technology (public technical number 2001-1745, published on March 15, 2001, Japan Society for Invention). Are listed.

Preferred combinations of non-chlorine organic solvents of the present invention are shown below, but the solvent of the present invention is not limited to these.
-Methyl acetate / acetone / methanol / ethanol / butanol (75/10/5/5/5 parts by mass),
-Methyl acetate / acetone / methanol / ethanol / propanol (75/10/5/5/5 parts by mass),
-Methyl acetate / acetone / methanol / butanol / cyclohexane (75/10/5/5/5 parts by mass),
-Methyl acetate / acetone / ethanol / butanol (81/8/7/4 parts by mass),
-Methyl acetate / acetone / ethanol / butanol (82/10/4/4 parts by mass),
-Methyl acetate / acetone / ethanol / butanol (80/10/4/6 parts by mass),
・ Methyl acetate / methyl ethyl ketone / methanol / butanol (80/10/5/5 parts by mass),
-Methyl acetate / acetone / methyl ethyl ketone / ethanol / isopropanol (75/10/10/5/7 parts by mass),
-Methyl acetate / cyclopentanone / methanol / isopropanol (80/10/5/8 parts by mass),
・ Methyl acetate / acetone / butanol (85/5/5 parts by mass),
Methyl acetate / cyclopentanone / acetone / methanol / butanol (60/15/15/5/6 parts by mass),
-Methyl acetate / cyclohexanone / methanol / hexane (70/20/5/5 parts by mass),
・ Methyl acetate / methyl ethyl ketone / acetone / methanol / ethanol (50/20/20/5/5 parts by mass),
・ Methyl acetate / 1, 3 dioxolane / methanol / ethanol (70/20/5/5 parts by mass),
-Methyl acetate / dioxane / acetone / methanol / ethanol (60/20/10/5/5 parts by mass),
-Methyl acetate / acetone / cyclopentanone / ethanol / isobutanol / cyclohexane (65/10/10/5/5/5 parts by mass)
・ Methyl formate / methyl ethyl ketone / acetone / methanol / ethanol (50/20/20/5/5 parts by mass),
-Methyl formate / acetone / ethyl acetate / ethanol / butanol / hexane (65/10/10/5/5/5 parts by mass),
Acetone / methyl acetoacetate / methanol / ethanol (65/20/10/5 parts by mass),
Acetone / cyclopentanone / ethanol / butanol (65/20/10/5 parts by mass),
Acetone / 1,3 dioxolane / ethanol / butanol (65/20/10/5 parts by mass),
・ 1,3 dioxolane / cyclohexanone / methyl ethyl ketone / methanol / butanol (55/20/10/5/5/5 parts by mass)

Furthermore, a cellulose acylate solution can also be used by the following method.
・ A cellulose acylate solution was prepared with methyl acetate / acetone / ethanol / butanol (81/8/7/4 parts by mass), filtered and concentrated, and then 2 parts by weight of butanol was added additionally. ・ Methyl acetate / acetone / ethanol / butanol ( (81/10/4/2 parts by mass), a cellulose acylate solution was prepared, and after filtration and concentration, 4 parts by weight of butanol was additionally added. Cellulose acylate with methyl acetate / acetone / ethanol (84/10/6 parts by mass) Add 5 parts by weight of butanol after preparing the solution, filtering and concentrating In addition to the non-chlorine organic solvent of the present technology, dichloromethane is added to 10% by mass or less of the total organic solvent amount of the present technology. You may make it contain.

(2) Chlorine-based solvent In preparing the cellulose acylate dope of the present invention, a chlorine-based organic solvent may be used as a main solvent in some cases. In the present invention, the chlorinated organic solvent is not particularly limited as long as the object can be achieved within a range in which cellulose acylate can be dissolved, cast and film-formed. These chlorinated organic solvents are preferably dichloromethane and chloroform, and particularly preferably dichloromethane. In addition, there is no particular problem in mixing an organic solvent other than the chlorinated organic solvent. In that case, it is necessary to use at least 50% by mass of dichloromethane.

  The chlorine-based organic solvent can be used in combination with the non-chlorine-based solvent as necessary. The non-chlorine organic solvent that can be used in combination with the chlorinated organic solvent is not particularly limited, but methyl acetate, ethyl acetate, methyl formate, ethyl formate, acetone, dioxolane, dioxane, ketones having 4 to 7 carbon atoms, or aceto It is preferable to use a non-chlorine organic solvent selected from acetates, alcohols having 1 to 10 carbon atoms or hydrocarbons. The non-chlorine organic solvent used in combination is more preferably methyl acetate, acetone, methyl formate, ethyl formate, methyl ethyl ketone, cyclopentanone, cyclohexanone, methyl acetyl acetate, methanol, ethanol, 1-propanol, 2-propanol, 1- It is a non-chlorine organic solvent selected from butanol, 2-butanol, and cyclohexanol, cyclohexane, and hexane.

A combination of a non-chlorine organic solvent and a chlorine organic solvent, which is a preferred main solvent of the present invention, is shown below, but the organic solvent used in the present invention is not limited to these.
Dichloromethane / methanol / ethanol / butanol (75/10/5/5/5 parts by mass),
Dichloromethane / acetone / methanol / propanol (80/10/5/5 parts by mass),
Dichloromethane / methanol / butanol / cyclohexane (75/10/5/5/5 parts by mass),
Dichloromethane / methyl ethyl ketone / methanol / butanol (80/10/5/5 parts by mass)
Dichloromethane / acetone / methyl ethyl ketone / ethanol / isopropanol (75/10/10/5/7 parts by mass),
Dichloromethane / cyclopentanone / methanol / isopropanol (80/10/5/8 parts by mass),
Dichloromethane / methyl acetate / butanol (80/10/10 parts by mass),
Dichloromethane / cyclohexanone / methanol / hexane (70/20/5/5 parts by mass),
・ Dichloromethane / methyl ethyl ketone / acetone / methanol / ethanol (50/20/20/5/5 parts by mass),
・ Dichloromethane / 1, 3 dioxolane / methanol / ethanol (70/20/5/5 parts by mass),
Dichloromethane / dioxane / acetone / methanol / ethanol (60/20/10/5/5 parts by mass),
Dichloromethane / acetone / cyclopentanone / ethanol / isobutanol / cyclohexane (65/10/10/5/5/5 parts by mass),
Dichloromethane / methyl ethyl ketone / acetone / methanol / ethanol (70/10/10/5/5 parts by mass),
Dichloromethane / acetone / ethyl acetate / ethanol / butanol / hexane (65/10/10/5/5/5 parts by mass),
・ Dichloromethane / methyl acetoacetate / methanol / ethanol (65/20/10/5 parts by mass),
Dichloromethane / cyclopentanone / ethanol / butanol (65/20/10/5 parts by mass),

(Preparation of dope)
The dope used in the present invention is a chlorinated organic solvent and a non-chlorinated organic solvent, and the cellulose acylate is 10 to 30% by mass, preferably 13 to 27% by mass, more preferably 15 to 25% by mass. % Dissolved. Prior to dissolution of cellulose acylate in a solvent, it is preferable to swell at 0 to 50 ° C. for 0.1 to 100 hours.
Various additives may be added before the swelling step, during or after the swelling step, and further during or after cooling and dissolution.

  In the present invention, it is preferable to use a cooling / heating method in order to dissolve cellulose acylate in an organic solvent. The cooling / heating method is described, for example, in JP-A-11-323017, JP-A-10-67860, JP-A-10-95854, JP-A-10-324774, and JP-A-11-302388. Can be used. That is, a solvent and cellulose acylate mixed and swollen can be dissolved using a screw-type kneader provided with a cooling jacket. Further, the dope of the present invention is preferably subjected to concentration and filtration, which are described in detail on page 25 of the Japan Society for Invention and Innovation (Publication No. 2001-1745, published on March 15, 2001, Japan Society for Invention). Can be used. Furthermore, it is preferable to reduce the viscosity of the dope by the method described above.

(Film formation)
The cellulose acylate film-forming method and equipment of the present invention can utilize the solution casting film-forming method and the solution casting film-forming apparatus that have been used in the conventional cellulose triacetate film production except for the conditions described above. it can. The dope prepared in the dissolving machine (kettle) is temporarily stored in a storage kettle and defoamed before final preparation. The dope is sent from the discharge port to a pressure die through a constant flow pump (for example, a pressure metering gear pump that can deliver a metered liquid with high accuracy by the number of rotations), and the dope is uniformly applied to a metal or other smooth support from the die (slit). And dried according to the method described above.

  Casting may be performed in a single layer, or two or more types of cellulose acylate solutions may be simultaneously and / or sequentially co-cast. When casting a cellulose acylate film composed of two or more layers, the types and concentrations of the cellulose acylate, solvent, and additive of the dope in each layer may be the same or different.

  After casting, after drying on a smooth casting support, it is peeled off and dried while transporting a dry-dried dope film (also referred to as web), but during this time (until after stripping from the smooth casting support) ) And drying according to the drying method described above. The drying method described above is preferably applied in the initial stage of drying in which the residual solvent concentration is 20% by mass or more.

  This late drying can use conventional methods. For example, the both ends of the web may be sandwiched between clips and conveyed and dried by a tenter while maintaining the width, may be dried while being conveyed by a roll, or a combination of these may be dried. A preferable drying temperature for the late drying is 50 to 200 ° C. and 0.1 to 10 hours.

  In the film forming step, the cellulose acylate film may be stretched. Stretching may be performed in either the casting direction (MD) or the width direction (TD), or may be performed in both directions. A preferable draw ratio is 1 to 80% in each direction, preferably 2 to 60%, and more preferably 3 to 50%. The stretching temperature is preferably 50 to 180 ° C, more preferably 70 to 150 ° C, and further preferably 80 to 140 ° C. The residual solvent in the film thus dried is preferably 0 to 5%, more preferably 0 to 2%, and further preferably 0 to 1%. After drying, trim both ends and wind up. A preferable width is 0.5 to 5 m, more preferably 0.7 to 3 m, and further preferably 1 to 2 m. A preferable winding length is 300 to 30 km, more preferably 500 to 10 km, and further preferably 1 to 7 km.

(surface treatment)
The cellulose acylate film can improve the adhesion between the cellulose acylate film and each functional layer (for example, the undercoat layer and the back layer) by optionally performing a surface treatment. For example, glow discharge treatment, ultraviolet irradiation treatment, corona treatment, flame treatment, acid or alkali treatment can be used. The glow discharge treatment here may be low-temperature plasma that occurs under a low-pressure gas of 10 ^{−3 to} 20 Torr, and is preferably a plasma treatment that is performed under atmospheric pressure. A plasma-excitable gas is a gas that is plasma-excited under the above conditions, and includes chlorofluorocarbons such as argon, helium, neon, krypton, xenon, nitrogen, carbon dioxide, tetrafluoromethane, and mixtures thereof. It is done. Details of these are described on pages 30 to 32 of the Japan Society for Invention and Innovation Technical Report (Public Technical Number 2001-1745, published on March 15, 2001, Japan Society for Invention).

  Note that, in the plasma treatment at atmospheric pressure which has been attracting attention in recent years, for example, irradiation energy of 20 to 500 Kgy is used under 10 to 1000 Kev, and more preferably irradiation energy of 20 to 300 Kgy is used under 30 to 500 Kev. Among these, an alkali saponification treatment is particularly preferable, and it is extremely effective as a surface treatment of a cellulose acylate film.

  The alkali saponification treatment may be immersed in a saponification solution or coated with a saponification solution. In the case of the dipping method, it can be achieved by passing an aqueous solution having a pH of 10 to 14 such as NaOH or KOH through a bath heated to 20 to 80 ° C. for 0.1 to 10 minutes, followed by neutralization, washing with water and drying.

  In the case of the coating method, a dip coating method, a curtain coating method, an extrusion coating method, a bar coating method, and an E-type coating method can be used. The solvent of the alkali saponification coating solution has good wettability because it is applied to the transparent support of the saponification solution, and the surface state remains good without forming irregularities on the surface of the transparent support by the saponification solution solvent. It is preferable to select a solvent to be maintained. Specifically, an alcohol solvent is preferable, and isopropyl alcohol is particularly preferable. An aqueous solution of a surfactant can also be used as a solvent. The alkali of the alkali saponification coating solution is preferably an alkali that dissolves in the above solvent, and more preferably KOH or NaOH. The pH of the saponification coating solution is preferably 10 or more, more preferably 12 or more. The reaction conditions during the alkali saponification are preferably 1 second to 5 minutes at room temperature, more preferably 5 seconds to 5 minutes at room temperature, and particularly preferably 20 seconds to 3 minutes at room temperature. After the alkali saponification reaction, it is preferable to wash the surface to which the saponification solution is applied after washing with water or acid and then washing with water. Also, the coating-type saponification treatment and the alignment film uncoating described later can be performed continuously, and the number of steps can be reduced. Specific examples of these saponification methods include the methods described in JP-A No. 2002-82226 and WO 02/46809.

  It is also preferable to provide an undercoat layer for adhesion to the functional layer. The undercoat layer may be applied after the above surface treatment or may be applied without the surface treatment. Details of the undercoat layer are described on page 32 of the Japan Society for Invention and Innovation Technical Report (Public Technical Number 2001-1745, published on March 15, 2001, Japan Society for Invention).

  These surface treatment and undercoating processes can be incorporated at the end of the film forming process, can be performed alone, or can be performed in the functional layer application process described later.

(Functional layer)
The cellulose acylate film obtained by the film forming method of the present invention is described on pages 32 to 45 of the Japan Society for Invention and Technology (public technical number 2001-1745, published on March 15, 2001, Japan Society for Invention). It is preferable to combine functional layers. Among these, application of a polarizing layer (polarizing plate), application of an optical compensation layer (optical compensation sheet), and application of an antireflection layer (antireflection film) are preferable.

(1) Application of polarizing layer (creation of polarizing plate)
[Material used]
Currently, a commercially available polarizing layer is generally produced by immersing a stretched polymer in a solution of iodine or dichroic dye in a bath and allowing the iodine or dichroic dye to penetrate into the binder. is there. As the polarizing film, a coating type polarizing film represented by Optiva Inc. can also be used. Iodine and dichroic dye in the polarizing film exhibit deflection performance by being oriented in the binder. As the dichroic dye, an azo dye, stilbene dye, pyrazolone dye, triphenylmethane dye, quinoline dye, oxazine dye, thiazine dye or anthraquinone dye is used. The dichroic dye is preferably water-soluble. The dichroic dye preferably has a hydrophilic substituent (eg, sulfo, amino, hydroxyl). For example, the compound as described in Invention Association public technique, public technical number 2001-1745, page 58 (issue date March 15, 2001) can be mentioned.

  As the binder for the polarizing film, either a polymer that can be crosslinked per se or a polymer that is crosslinked by a crosslinking agent can be used, and a plurality of combinations thereof can be used. Examples of the binder include methacrylate copolymers, styrene copolymers, polyolefins, polyvinyl alcohols and modified polyvinyl alcohols, poly (N-methylolacrylamide) described in [0022] column of JP-A-8-338913, Polyester, polyimide, vinyl acetate copolymer, carboxymethyl cellulose, polycarbonate and the like are included. Silane coupling agents can be used as the polymer. Water-soluble polymers (eg, poly (N-methylolacrylamide), carboxymethylcellulose, gelatin, polyvinyl alcohol, modified polyvinyl alcohol) are preferred, gelatin, polyvinyl alcohol and modified polyvinyl alcohol are more preferred, and polyvinyl alcohol and modified polyvinyl alcohol are most preferred. . It is particularly preferable to use two types of polyvinyl alcohol or modified polyvinyl alcohol having different degrees of polymerization. The saponification degree of polyvinyl alcohol is preferably 70 to 100%, more preferably 80 to 100%. It is preferable that the polymerization degree of polyvinyl alcohol is 100-5000. The modified polyvinyl alcohol is described in JP-A-8-338913, JP-A-9-152509, and JP-A-9-316127. Two or more kinds of polyvinyl alcohol and modified polyvinyl alcohol may be used in combination.

  The lower limit of the binder thickness of the polarizing film is preferably 10 μm. The upper limit of the thickness is preferably as thin as possible from the viewpoint of light leakage of the liquid crystal display device. It is preferably not more than a commercially available polarizing plate (about 30 μm), preferably 25 μm or less, and more preferably 20 μm or less.

  The binder of the polarizing film may be cross-linked. A polymer or monomer having a crosslinkable functional group may be mixed in the binder, or a crosslinkable functional group may be imparted to the binder polymer itself. Crosslinking can be performed by light, heat, or pH change, and a binder having a crosslinked structure can be formed. The crosslinking agent is described in US Reissue Patent 23297. Boron compounds (eg, boric acid, borax) can also be used as a crosslinking agent. The addition amount of the crosslinking agent in the binder is preferably 0.1 to 20% by mass with respect to the binder. The orientation of the polarizing element and the wet heat resistance of the polarizing film are improved. Even after the crosslinking reaction is completed, the unreacted crosslinking agent is preferably 1.0% by mass or less, and more preferably 0.5% by mass or less. By doing in this way, a weather resistance improves.

[Stretching]
The polarizing film is preferably dyed with iodine or a dichroic dye after the polarizing film is stretched (stretching method) or rubbed (rubbing method).

  In the stretching method, the stretching ratio is preferably 2.5 to 30.0 times, and more preferably 3.0 to 10.0 times. Stretching can be performed by dry stretching in air. Moreover, you may implement wet extending | stretching in the state immersed in water. The stretch ratio of dry stretching is preferably 2.5 to 5.0 times, and the stretch ratio of wet stretching is preferably 3.0 to 10.0 times. Stretching may be performed in parallel to the MD direction (parallel stretching), or may be performed in an oblique direction (oblique stretching). These stretching operations may be performed once or divided into several times. By dividing into several times, it is possible to stretch more uniformly even at high magnification. More preferred is oblique stretching in which the film is stretched with an inclination of 10 to 80 ° in the oblique direction.

(A) Parallel stretching method Prior to stretching, the PVA film is swollen. The degree of swelling is 1.2 to 2.0 times (weight ratio before swelling and after swelling). Thereafter, the film is stretched at a bath temperature of 15 to 50 ° C., particularly 17 to 40 ° C. in an aqueous medium bath or a dye bath for dissolving a dichroic substance while being continuously conveyed through a guide roll or the like. Stretching can be achieved by gripping with two pairs of nip rolls and increasing the conveyance speed of the subsequent nip roll to be higher than that of the previous nip roll. The draw ratio is based on the length ratio after stretching / initial state (hereinafter the same), but the draw ratio is preferably 1.2 to 3.5 times, particularly preferably 1.5 to 3.times. 0 times. Then, it is made to dry at 50-90 degreeC, and a polarizing film is obtained.

(B) Diagonal stretch method As this stretch method, the method of extending | stretching using the tenter which protruded in the diagonal direction as described in Unexamined-Japanese-Patent No. 2002-86554 can be used. Since this stretching is performed in the air, it is necessary to make it easy to stretch by adding water in advance. A preferable moisture content is 5 to 100%, more preferably 10 to 100%.

  The temperature during stretching is preferably 40 to 90 ° C, and more preferably 50 to 80 ° C. The humidity is preferably 50 to 100% RH, more preferably 70 to 100% RH, and further preferably 80 to 100% RH. The traveling speed in the longitudinal direction is preferably 1 m / min or more, and more preferably 3 m / min or more. After the stretching, it is preferable to dry at 50 to 100 ° C., preferably 60 to 90 ° C., for 0.5 to 10 minutes, preferably 1 to 5 minutes.

  The absorption axis of the polarizing film thus obtained is preferably 10 to 80 °, more preferably 30 to 60 °, and substantially 45 ° (40 to 50 °). Further preferred.

[Lamination]
The saponified cellulose acylate film and a polarizing layer prepared by stretching are bonded to prepare a polarizing plate. The laminating direction is preferably such that the casting axis direction of the cellulose acylate film and the stretching axis direction of the polarizing plate are 45 °.

  The adhesive for bonding is not particularly limited, but examples thereof include PVA resins (including modified PVA such as acetoacetyl group, sulfonic acid group, carboxyl group, oxyalkylene group) and boron compound aqueous solution. preferable. The thickness of the adhesive layer is preferably 0.01 to 10 μm after drying, and particularly preferably 0.05 to 5 μm.

  The polarizing plate thus obtained preferably has a higher light transmittance and a higher degree of polarization. The transmittance of the polarizing plate is preferably in the range of 30 to 50%, more preferably in the range of 35 to 50%, and most preferably in the range of 40 to 50% in light having a wavelength of 550 nm. . The degree of polarization is preferably in the range of 90 to 100%, more preferably in the range of 95 to 100%, and most preferably in the range of 99 to 100% in light having a wavelength of 550 nm.

  Furthermore, the polarizing plate obtained in this way can produce a circularly polarized light by laminating λ / 4 plates. In this case, the lamination is performed so that the crossing angle between the slow axis of the λ / 4 plate and the absorption axis of the polarizing plate is 45 °. At this time, the λ / 4 plate is not particularly limited, but preferably has a wavelength dependency such that the lower the wavelength, the smaller the retardation. Further, it is preferable to use a λ / 4 plate comprising a polarizing film having an absorption axis inclined by 20 to 70 ° with respect to the longitudinal direction and an optically anisotropic layer made of a liquid crystalline compound.

(2) Application of optical compensation layer (creation of optical compensation sheet)
The optically anisotropic layer is for compensating the liquid crystal compound in the liquid crystal cell in the black display of the liquid crystal display device, and forms an alignment film on the cellulose acylate film, and further provides an optically anisotropic layer. It is formed by doing.

[Alignment film]
An alignment film is provided on the surface-treated cellulose acylate film. This film has a function of defining the alignment direction of liquid crystalline molecules. However, if the alignment state is fixed after the alignment of the liquid crystalline compound, the alignment film plays the role, and thus is not necessarily an essential component of the present invention. That is, it is possible to produce the polarizing plate of the present invention by transferring only the optically anisotropic layer on the alignment film in which the alignment state is fixed onto the polarizer.

  The alignment film is an organic compound (eg, ω-tricosanoic acid) formed by rubbing treatment of an organic compound (preferably polymer), oblique deposition of an inorganic compound, formation of a layer having a microgroove, or Langmuir-Blodgett method (LB film). , Dioctadecylmethylammonium chloride, methyl stearylate). Furthermore, an alignment film in which an alignment function is generated by application of an electric field, application of a magnetic field or light irradiation is also known.

  The alignment film is preferably formed by polymer rubbing treatment. In principle, the polymer used for the alignment film has a molecular structure having a function of aligning liquid crystal molecules.

  In the present invention, in addition to the function of aligning liquid crystal molecules, the crosslinkability of bonding side chains having a crosslinkable functional group (eg, double bond) to the main chain or aligning liquid crystal molecules. It is preferable to introduce a functional group into the side chain.

  As the polymer used in the alignment film, either a polymer that can be crosslinked by itself or a polymer that is crosslinked by a crosslinking agent can be used, and a plurality of combinations thereof can be used. Examples of such polymers include, for example, methacrylate copolymers, styrene copolymers, polyolefins, polyvinyl alcohols and modified polyvinyl alcohols described in JP-A-8-338913, column [0022], poly (N -Methylol acrylamide), polyester, polyimide, vinyl acetate copolymer, carboxymethyl cellulose, polycarbonate and the like. Silane coupling agents can also be used as the polymer. The polymer used for the alignment film is preferably a polymer selected from water-soluble polymers (eg, poly (N-methylolacrylamide), carboxymethylcellulose, gelatin, polyvinyl alcohol, and modified polyvinyl alcohol), more preferably gelatin and polyvinyl alcohol. And a polymer selected from modified polyvinyl alcohol, most preferably polyvinyl alcohol or modified polyvinyl alcohol. It is also preferable to use two types of polyvinyl alcohol or modified polyvinyl alcohol having different degrees of polymerization. The saponification degree of polyvinyl alcohol is preferably 70 to 100%, and more preferably 80 to 100%. It is preferable that the polymerization degree of polyvinyl alcohol is 100-5000.

  A side chain having a function of aligning liquid crystal molecules generally has a hydrophobic group as a functional group. The specific type of functional group is determined according to the type of liquid crystal molecule and the required alignment state. For example, the modifying group of the modified polyvinyl alcohol can be introduced by copolymerization modification, chain transfer modification or block polymerization modification. Examples of modifying groups include hydrophilic groups (carboxylic acid groups, sulfonic acid groups, phosphonic acid groups, amino groups, ammonium groups, amide groups, thiol groups, etc.), hydrocarbon groups having 10 to 100 carbon atoms, fluorine atoms Substituted hydrocarbon groups, thioether groups, polymerizable groups (unsaturated polymerizable groups, epoxy groups, azirinidyl groups, etc.), alkoxysilyl groups (trialkoxy, dialkoxy, monoalkoxy) and the like can be mentioned. Specific examples of these modified polyvinyl alcohol compounds include those described in, for example, columns [0022] to [0145] of JP-A No. 2000-155216 and columns [0018] to [0022] of JP-A No. 2002-62426. Can be mentioned.

  When a side chain having a crosslinkable functional group is bonded to the main chain of the alignment film polymer, or a crosslinkable functional group is introduced into a side chain having a function of aligning liquid crystalline molecules, the alignment film polymer and the optically anisotropic film The polyfunctional monomer contained in the conductive layer can be copolymerized. As a result, not only between the polyfunctional monomer and the polyfunctional monomer, but also between the alignment film polymer and the alignment film polymer and between the polyfunctional monomer and the alignment film polymer is firmly bonded by a covalent bond. Therefore, the strength of the optical compensation sheet can be remarkably improved by introducing the crosslinkable functional group into the alignment film polymer.

  The crosslinkable functional group of the alignment film polymer preferably contains a polymerizable group in the same manner as the polyfunctional monomer. Specific examples include those described in JP-A-2000-155216, columns [0080] to [0100]. Apart from the crosslinkable functional group, the alignment film polymer can also be crosslinked using a crosslinking agent.

  Examples of the crosslinking agent include aldehydes, N-methylol compounds, dioxane derivatives, compounds that act by activating carboxyl groups, active vinyl compounds, active halogen compounds, isoxazole, and dialdehyde starch. Two or more kinds of crosslinking agents may be used in combination. Specifically, for example, compounds described in columns [0023] to [024] of JP-A No. 2002-62426 may be mentioned. Aldehydes having high reaction activity, particularly glutaraldehyde are preferred.

  The addition amount of the crosslinking agent is preferably 0.1 to 20% by mass, and more preferably 0.5 to 15% by mass with respect to the mass of the polymer. The amount of the unreacted crosslinking agent remaining in the alignment film is preferably 1.0% by mass or less, and more preferably 0.5% by mass or less. By adjusting in this way, even if the alignment film is used for a long time in a liquid crystal display device or left in a high temperature and high humidity atmosphere for a long time, sufficient durability without reticulation can be obtained.

  The alignment film can be basically formed by coating the polymer as an alignment film forming material and a transparent support containing a cross-linking agent, followed by drying by heating (crosslinking) and rubbing treatment. As described above, the crosslinking reaction may be performed at any time after coating on the transparent support. When a water-soluble polymer such as polyvinyl alcohol is used as the alignment film forming material, the coating solution is preferably a mixed solvent of an organic solvent (eg, methanol) having a defoaming action and water. The ratio of water: methanol is preferably 0: 100 to 99: 1, and more preferably 0: 100 to 91: 9. Thereby, generation | occurrence | production of a bubble is suppressed and the defect of the layer surface of an orientation film and also an optically anisotropic layer reduces remarkably.

  The alignment film is preferably applied by spin coating, dip coating, curtain coating, extrusion coating, rod coating, or roll coating. A rod coating method is particularly preferable. Moreover, it is preferable that the film thickness after drying is 0.1-10 micrometers. Heat drying can be performed at 20-110 degreeC. In order to form sufficient crosslinking, the temperature is preferably 60 to 100 ° C, more preferably 80 to 100 ° C. The drying time can be 1 minute to 36 hours, preferably 1 to 30 minutes. The pH is also preferably set to an optimum value for the cross-linking agent to be used, and when glutaraldehyde is used, the pH is 4.5 to 5.5, and pH 5 is particularly preferable.

  The alignment film is provided on the transparent support or the undercoat layer. The alignment film can be obtained by rubbing the surface after crosslinking the polymer layer as described above.

  For the rubbing treatment, a treatment method widely adopted as a liquid crystal alignment treatment process of LCD can be applied. That is, a method of obtaining the orientation by rubbing the surface of the orientation film in a certain direction using paper, gauze, felt, rubber, nylon, polyester fiber or the like can be used. In general, it is carried out by rubbing several times using a cloth in which fibers having a uniform length and thickness are flocked on average.

  When industrially implemented, this is achieved by bringing a rotating rubbing roll into contact with the film with the polarizing layer being transported. However, the roundness, cylindricity, and deflection (eccentricity) of the rubbing roll can be any. Is preferably 30 μm or less. The wrap angle of the film on the rubbing roll is preferably 0.1 to 90 °. However, as described in JP-A-8-160430, a stable rubbing treatment can be obtained by winding 360 ° or more. As for the conveyance speed of a film, 1-100 m / min is preferable. It is preferable to select an appropriate rubbing angle in the range of 0 to 60 °. When used in a liquid crystal display device, the angle is preferably 40 to 50 °, and particularly preferably 45 °.

  The thickness of the alignment film thus obtained is preferably 0.1 to 10 μm, preferably 0.1 to 5 μm, more preferably 0.2 to 3 μm.

  Next, the liquid crystalline molecules of the optically anisotropic layer are aligned on the alignment film. Thereafter, as necessary, the alignment film polymer and the polyfunctional monomer contained in the optically anisotropic layer are reacted, or the alignment film polymer is crosslinked using a crosslinking agent.

  The liquid crystalline molecules used for the optically anisotropic layer include rod-like liquid crystalline molecules and discotic liquid crystalline molecules. The rod-like liquid crystal molecules and the disc-like liquid crystal molecules may be high-molecular liquid crystals or low-molecular liquid crystals, and further include those in which the low-molecular liquid crystals are crosslinked and no longer exhibit liquid crystallinity.

[Rod-like liquid crystalline molecules]
Examples of rod-like liquid crystalline molecules include azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, alkoxy-substituted phenylpyrimidines. , Phenyldioxanes, tolanes and alkenylcyclohexylbenzonitriles are preferably used.

  The rod-like liquid crystalline molecule includes a metal complex. In addition, a liquid crystal polymer containing a rod-like liquid crystalline molecule in a repeating unit can also be used as the rod-like liquid crystalline molecule. In other words, the rod-like liquid crystal molecule may be bonded to a (liquid crystal) polymer.

  For details on rod-like liquid crystalline molecules, see Chapter 4, Chapter 7 and Chapter 11 of the Chemical Chemistry of the Quarterly Chemical Review Vol. 22, Liquid Crystal Chemistry (1994), and the 142nd Committee of the Japan Society for the Promotion of Science. The description in Chapter 3 of the volume can be referred to.

  The birefringence of the rod-like liquid crystalline molecule is preferably in the range of 0.001 to 0.7, preferably 0.01 to 0.5, and more preferably 0.03 to 0.4.

  The rod-like liquid crystalline molecule preferably has a polymerizable group in order to fix its alignment state. The polymerizable group is preferably a radical polymerizable unsaturated group or a cationic polymerizable group. Specifically, for example, the polymerizable group described in columns [0064] to [0086] of JP-A No. 2002-62427 can be used. And polymerizable liquid crystal compounds.

[Disc liquid crystalline molecules]
Discotic liquid crystal molecules include C. Destrade et al., Benzene derivatives described in Mol. Cryst. Vol. 71, p. 111 (1981), C. Destrade et al., Mol. Cryst. 122, 141 (1985), Physics lett, A, 78, 82 (1990), a research report of B. Kohne et al., Angew. Chem. 96, 70 (1984), JM Lehn et al., J. Chem. Commun., 1794 (1985), J. Zhang et al., J. Am. Chem. Soc. 116 Volume 2, page 2655 (1994) includes azacrown and phenylacetylene macrocycles.

  As a discotic liquid crystalline molecule, a compound having liquid crystallinity having a structure in which a linear alkyl group, an alkoxy group, and a substituted benzoyloxy group are radially substituted as a side chain of the mother nucleus with respect to the mother nucleus at the center of the molecule Is also included. The molecule or the assembly of molecules is preferably a compound having rotational symmetry and imparting a certain orientation. In the optically anisotropic layer formed from the discotic liquid crystalline molecules, the compound finally contained in the optically anisotropic layer does not need to be a discotic liquid crystalline molecule. Also included are compounds having a group that reacts with heat or light and, as a result, polymerized or crosslinked by reaction with heat or light, resulting in a high molecular weight and loss of liquid crystallinity. Preferred examples of the discotic liquid crystalline molecules are described in JP-A-8-50206. The polymerization of discotic liquid crystalline molecules is described in JP-A-8-27284.

  In order to fix the discotic liquid crystalline molecules by polymerization, it is necessary to bond a polymerizable group as a substituent to the discotic core of the discotic liquid crystalline molecules. A compound in which the discotic core and the polymerizable group are bonded via a linking group is preferable, whereby the orientation state can be maintained even in the polymerization reaction. Examples thereof include compounds described in JP-A 2000-155216, columns [0151] to “0168”.

  In hybrid alignment, the angle between the major axis (disk surface) of the discotic liquid crystalline molecule and the surface of the polarizing film increases or decreases in the depth direction of the optically anisotropic layer and with increasing distance from the surface of the polarizing film. is doing. The angle preferably decreases with increasing distance. Further, the change in angle can be a continuous increase, a continuous decrease, an intermittent increase, an intermittent decrease, a change including a continuous increase and a continuous decrease, or an intermittent change including an increase and a decrease. The intermittent change includes a region where the inclination angle does not change in the middle of the thickness direction. Even if the angle includes a region where the angle does not change, the angle only needs to increase or decrease as a whole. Furthermore, it is preferable that the angle changes continuously.

  The average direction of the major axis of the discotic liquid crystalline molecules on the polarizing film side can be generally adjusted by selecting a discotic liquid crystalline molecule or an alignment film material, or by selecting a rubbing treatment method. In addition, the major axis (disk surface) direction of the surface-side (air-side) discotic liquid crystalline molecules is generally adjusted by selecting the type of additive used together with the discotic liquid crystalline molecules or discotic liquid crystalline molecules. be able to. Examples of the additive used together with the discotic liquid crystalline molecule include a plasticizer, a surfactant, a polymerizable monomer and a polymer. The degree of change in the orientation direction of the major axis can also be adjusted by selecting liquid crystalline molecules and additives as described above.

[Other compositions of optically anisotropic layer]
Along with the liquid crystal molecules, a plasticizer, a surfactant, a polymerizable monomer, and the like can be used in combination to improve the uniformity of the coating film, the strength of the film, the orientation of the liquid crystal molecules, and the like. It is preferable that the compound has compatibility with the liquid crystal molecules and can change the tilt angle of the liquid crystal molecules or does not inhibit the alignment.

  Examples of the polymerizable monomer include radically polymerizable or cationically polymerizable compounds. Preferably, it is a polyfunctional radically polymerizable monomer and is preferably copolymerizable with the above-described polymerizable group-containing liquid crystal compound. Examples thereof include those described in columns [0018] to [0020] of JP-A No. 2002-296423. The amount of the compound added is generally in the range of 1 to 50% by mass and preferably in the range of 5 to 30% by mass with respect to the discotic liquid crystalline molecules.

  Examples of the surfactant include conventionally known compounds, and fluorine compounds are particularly preferable. Specifically, for example, compounds described in columns [0028] to [0056] of JP-A No. 2001-330725 are exemplified.

The polymer used together with the discotic liquid crystalline molecule is preferably capable of changing the tilt angle of the discotic liquid crystalline molecule. Examples of such polymers include cellulose esters. Preferable examples of the cellulose ester include those described in the [0178] column of JP-A No. 2000-155216. The addition amount of the polymer is preferably 0.1 to 10% by mass, and preferably 0.1 to 8% by mass with respect to the mass of the liquid crystal molecule so as not to disturb the alignment of the liquid crystal molecules. Further preferred.
The discotic nematic liquid crystal phase-solid phase transition temperature of the discotic liquid crystalline molecules is preferably 70 to 300 ° C, and more preferably 70 to 170 ° C.

[Formation of optically anisotropic layer]
The optically anisotropic layer can be formed by applying a coating liquid containing liquid crystalline molecules and, if necessary, a polymerization initiator described later and optional components on the alignment film.
As a solvent used for preparing the coating solution, an organic solvent is preferably used. Examples of organic solvents include amides (eg, N, N-dimethylformamide), sulfoxides (eg, dimethyl sulfoxide), heterocyclic compounds (eg, pyridine), hydrocarbons (eg, benzene, hexane), alkyl halides (eg, , Chloroform, dichloromethane, tetrachloroethane), esters (eg, methyl acetate, butyl acetate), ketones (eg, acetone, methyl ethyl ketone), ethers (eg, tetrahydrofuran, 1,2-dimethoxyethane). Alkyl halides and ketones are preferred. Two or more organic solvents may be used in combination.

  The coating liquid can be applied by a known method (eg, wire bar coating method, extrusion coating method, direct gravure coating method, reverse gravure coating method, die coating method).

  The thickness of the optically anisotropic layer is preferably 0.1 to 20 μm, more preferably 0.5 to 15 μm, and most preferably 1 to 10 μm.

[Fixing the alignment state of liquid crystalline molecules]
The aligned liquid crystal molecules can be fixed while maintaining the alignment state. The immobilization is preferably performed by a polymerization reaction. The polymerization reaction includes a thermal polymerization reaction using a thermal polymerization initiator and a photopolymerization reaction using a photopolymerization initiator, and a photopolymerization reaction is preferred.

  Examples of the photopolymerization initiator include α-carbonyl compounds (described in US Pat. Nos. 2,367,661 and 2,367,670), acyloin ether (described in US Pat. No. 2,448,828), α-hydrocarbon substituted aromatic acyloin. Compound (described in US Pat. No. 2,722,512), polynuclear quinone compound (described in US Pat. Nos. 3,046,127 and 2,951,758), a combination of triarylimidazole dimer and p-aminophenyl ketone (US Pat. No. 3,549,367) Description), acridine and phenazine compounds (JP-A-60-105667, U.S. Pat. No. 4,239,850) and oxadiazole compounds (U.S. Pat. No. 4,212,970).

  The amount of the photopolymerization initiator used is preferably in the range of 0.01 to 20% by mass, more preferably in the range of 0.5 to 5% by mass, based on the solid content of the coating solution.

It is preferable to use ultraviolet rays for light irradiation for polymerization of liquid crystalline molecules. The irradiation energy is preferably in the range of 20~50J / cm ^2, more preferably in the range of 20~5000mJ / cm ^2, and still more preferably in the range of 100 to 800 mJ / cm ^2. In order to accelerate the photopolymerization reaction, light irradiation may be performed under heating conditions.

  A protective layer may be provided on the optically anisotropic layer. The protective layer is not particularly limited as long as it is a transparent resin, and examples thereof include thermoplastic resins such as cellulose derivatives, polyesters, polycarbonates, and polyacrylates, and thermosetting resins such as cross-linkable acrylic resins and epoxy resins. The thickness of the protective layer is preferably 0.1 to 10 μm, more preferably 0.2 to 5 μm, and further preferably 0.2 to 3 μm.

  It is also preferable to combine the optical compensation film and the polarizing layer. Specifically, the optically anisotropic layer is formed by applying the coating liquid for the optically anisotropic layer as described above to the surface of the polarizing film. As a result, a thin polarizing plate having a small stress (strain × cross-sectional area × elastic modulus) associated with the dimensional change of the polarizing film is produced without using a polymer film between the polarizing film and the optically anisotropic layer. . When the polarizing plate according to the present invention is attached to a large liquid crystal display device, an image with high display quality can be displayed without causing problems such as light leakage.

  The inclination angle of the polarizing layer and the optical compensation layer may be stretched so as to match the angle formed between the transmission axis of the two polarizing plates bonded to both sides of the liquid crystal cell constituting the LCD and the vertical or horizontal direction of the liquid crystal cell. preferable. A normal inclination angle is 45 °. Recently, however, devices that are not necessarily 45 ° have been developed in transmissive, reflective, and transflective LCDs, and it is preferable that the stretching direction can be arbitrarily adjusted in accordance with the design of the LCD.

[Liquid Crystal Display]
Each liquid crystal mode in which such an optical compensation film is used will be described.
(TN mode liquid crystal display)
It is most frequently used as a color TFT liquid crystal display device and is described in many documents. The alignment state in the liquid crystal cell in the TN mode black display is an alignment state in which the rod-like liquid crystalline molecules rise at the center of the cell and the rod-like liquid crystalline molecules lie in the vicinity of the cell substrate.
(OCB mode liquid crystal display)

  This is a bend alignment mode liquid crystal cell in which rod-like liquid crystal molecules are aligned in a substantially opposite direction (symmetrically) between the upper part and the lower part of the liquid crystal cell. Liquid crystal display devices using a bend alignment mode liquid crystal cell are disclosed in US Pat. Nos. 4,583,825 and 5,410,422. Since the rod-like liquid crystal molecules are symmetrically aligned at the upper and lower portions of the liquid crystal cell, the bend alignment mode liquid crystal cell has a self-optical compensation function. Therefore, this liquid crystal mode is also called an OCB (Optically Compensatory Bend) liquid crystal mode.

  Similarly to the TN mode, the liquid crystal cell in the OCB mode is in a black display, and the alignment state in the liquid crystal cell is such that the rod-like liquid crystalline molecules rise at the center of the cell and the rod-like liquid crystalline molecules lie near the cell substrate. .

(VA mode liquid crystal display device)
The feature is that the rod-like liquid crystalline molecules are oriented substantially vertically when no voltage is applied. In the VA mode liquid crystal cell, (1) the rod-like liquid crystalline molecules are oriented substantially vertically when no voltage is applied. In addition to a narrowly defined VA mode liquid crystal cell (described in JP-A-2-176625) that is aligned substantially horizontally when a voltage is applied, (2) the VA mode is multi-domained to expand the viewing angle ( Liquid crystal cell (in MVA mode) (SID97, Digest of tech. Papers (preliminary report) 28 (1997) 845 described), (3) Rod-like liquid crystal molecules are aligned substantially vertically when no voltage is applied, and twisted This includes a liquid crystal cell in the domain alignment mode (n-ASM mode) (described in the proceedings of 58-59 (1998) of the Japanese Liquid Crystal Society) and (4) a SURVAVAL mode liquid crystal cell (presented at LCD International 98).

(Other liquid crystal display devices)
The ECB mode and STN mode liquid crystal display devices can be optically compensated in the same way as described above.

(3) Application of antireflection layer (antireflection film)
The antireflection film generally includes a low refractive index layer which is also an antifouling layer, and a layer having a refractive index higher than at least one low refractive index layer (ie, a high refractive index layer and a medium refractive index layer) as a transparent substrate. It is provided above.

  Colloidal metal by multilayer deposition of transparent thin films of inorganic compounds (metal oxides, etc.) with different refractive indexes by chemical vapor deposition (CVD) method, physical vapor deposition (PVD) method, sol-gel method of metal compounds such as metal alkoxides Examples include a method of forming a thin film by post-processing (ultraviolet irradiation: JP-A-9-157855, plasma processing: JP-A-2002-327310) after forming an oxide particle film.

  On the other hand, various antireflection films formed by laminating and applying a thin film in which inorganic particles are dispersed in a matrix have been proposed as an antireflection film having high productivity. The antireflection film which consists of the antireflection layer which provided the anti-glare property which the antireflection film by application | coating as mentioned above provided the surface of the uppermost layer with the shape of a fine unevenness | corrugation is also mentioned.

  The antireflection layer in the cellulose acylate film of the present invention may be produced by any of the above methods, but an antireflection layer obtained by a coating method (coating type) is particularly preferred.

[Layer structure of coated antireflection film]
An antireflection film comprising a layer structure of at least a middle refractive index layer, a high refractive index layer, and a low refractive index layer (outermost layer) on the substrate is designed to have a refractive index satisfying the following relationship.
Refractive index of high refractive index layer> refractive index of medium refractive index layer> refractive index of transparent support> refractive index of low refractive index layer

  A hard coat layer may be provided between the transparent support and the medium refractive index layer. Furthermore, it may consist of a medium refractive index hard coat layer, a high refractive index layer and a low refractive index layer. Examples thereof include JP-A-8-122504, JP-A-8-110401, JP-A-10-300902, JP-A-2002-243906, JP-A-2000-11706, and the like. Other functions may be imparted to each layer, for example, an antifouling low refractive index layer or an antistatic high refractive index layer (eg, JP-A-10-206603, JP-A-2002). -243906 gazette etc.) etc. can also be formed.

  The haze of the antireflection film is preferably 5% or less, more preferably 3% or less. Further, the strength of the film is preferably H or more, more preferably 2H or more, and most preferably 3H or more in a pencil hardness test according to JIS K5400.

[High refractive index layer and medium refractive index layer]
The layer having a high refractive index of the antireflection film is composed of a curable film containing at least an ultrafine particle of an inorganic compound having a high refractive index having an average particle diameter of 100 nm or less and a matrix binder.
Examples of the high refractive index inorganic compound fine particles include inorganic compounds having a refractive index of 1.65 or more, preferably those having a refractive index of 1.9 or more. Examples thereof include oxides such as Ti, Zn, Sb, Sn, Zr, Ce, Ta, La, and In, and composite oxides containing these metal atoms.

  In order to obtain such ultrafine particles, the surface of the particles is treated with a surface treatment agent (for example, silane coupling agents, etc .: JP-A-11-295503, JP-A-11-153703, JP-A-2000-9908). No. 1, anionic compound or organometallic coupling agent: Japanese Patent Laid-Open No. 2001-310432, a core-shell structure with high refractive index particles as a core (Japanese Patent Laid-Open No. 2001-166104, etc.), a specific Use of a dispersant (for example, JP-A No. 11-153703, U.S. Pat. No. 6,210,858 B1, JP-A No. 2002-276069, etc.) and the like.

  Examples of the material forming the matrix include conventionally known thermoplastic resins and curable resin films.

  Furthermore, it is selected from a polyfunctional compound-containing composition containing at least two radically polymerizable and / or cationically polymerizable groups, an organometallic compound containing a hydrolyzable group, and a partial condensate composition thereof. At least one composition is preferred. Examples thereof include compounds described in JP-A Nos. 2000-47004, 2001-315242, 2001-31871, and 2001-296401.

  A curable film prepared from a colloidal metal oxide obtained from a hydrolyzed condensate of a metal alkoxide and a metal alkoxide composition is also preferable (see, for example, compounds described in JP-A No. 2001-293818). .

  The refractive index of the high refractive index layer is generally 1.70 to 2.20, preferably 1.80 to 2.10. The thickness of the high refractive index layer is preferably 5 nm to 10 μm, more preferably 10 nm to 1 μm. The refractive index of the middle refractive index layer is adjusted to be a value between the refractive index of the low refractive index layer and the refractive index of the high refractive index layer. The refractive index of the middle refractive index layer is preferably 1.50 to 1.70.

[Low refractive index layer]
The low refractive index layer is sequentially laminated on the high refractive index layer. The refractive index of the low refractive index layer is 1.20 to 1.55, preferably 1.30 to 1.50. The low refractive index layer is preferably constructed as an outermost layer having scratch resistance and antifouling properties. As a means for greatly improving the scratch resistance, imparting slipperiness to the surface is effective, and conventionally known thin film layer means such as introduction of silicone or introduction of fluorine can be applied.

  The refractive index of the fluorine-containing compound is preferably 1.35 to 1.50, more preferably 1.36 to 1.47. Moreover, it is preferable that a fluorine-containing compound is a compound containing the crosslinkable or polymeric functional group which contains a fluorine atom in 35-80 mass%. For example, columns [0018] to [0026] in JP-A-9-222503, columns [0019] to [0030] in JP-A-11-38202, and [0027] to [0028] in JP-A-2001-40284. Column, compounds described in JP-A No. 2000-284102, and the like.

  The silicone compound is a compound having a polysiloxane structure, and preferably contains a curable functional group or a polymerizable functional group in the polymer chain and has a crosslinked structure in the film. For example, reactive silicone (eg, Silaplane (manufactured by Chisso Corporation), silanol group-containing polysiloxane (Japanese Patent Laid-Open No. 11-258403, etc.) and the like can be mentioned.

  The crosslinking or polymerization reaction of the fluorine-containing and / or siloxane polymer having a crosslinking or polymerizable group is performed simultaneously with or after the application of the coating composition for forming the outermost layer containing a polymerization initiator, a sensitizer and the like. It is preferable to carry out by light irradiation or heating.

  Also preferred is a sol-gel cured film in which an organometallic compound such as a silane coupling agent and a specific fluorine-containing hydrocarbon group-containing silane coupling agent are cured by a condensation reaction in the presence of a catalyst. For example, a polyfluoroalkyl group-containing silane compound or a partially hydrolyzed condensate thereof (Japanese Patent Laid-Open Nos. 58-142958, 58-147483, 58-147484, Japanese Patent Laid-Open Nos. 9-157582, 11) -106704), silyl compounds containing a poly "perfluoroalkyl ether" group which is a fluorine-containing long chain group (Japanese Patent Application Laid-Open Nos. 2000-117902, 2001-48590, 2002) 53804), and the like.

  The low refractive index layer has an average primary particle diameter of 1 to 150 nm such as a filler (for example, silicon dioxide (silica), fluorine-containing particles (magnesium fluoride, calcium fluoride, barium fluoride)) as an additive other than the above. Low refractive index inorganic compounds, organic fine particles described in [0020] to [0038] in JP-A-11-3820, etc.), silane coupling agents, slip agents, surfactants, and the like can be contained.

  When the low refractive index layer is formed in the lower layer of the outermost layer, the low refractive index layer may be formed by a vapor phase method (vacuum deposition method, sputtering method, ion plating method, plasma CVD method, etc.). The coating method is preferable because it can be manufactured at a low cost.

  The film thickness of the low refractive index layer is preferably 30 to 200 nm, more preferably 50 to 150 nm, and most preferably 60 to 120 nm.

[Hard coat layer]
The hard coat layer is provided on the surface of the transparent support in order to impart physical strength to the antireflection film. In particular, it is preferably provided between the transparent support and the high refractive index layer. The hard coat layer is preferably formed by a crosslinking reaction or a polymerization reaction of a light and / or heat curable compound. The curable functional group is preferably a photopolymerizable functional group, and the hydrolyzable functional group-containing organometallic compound is preferably an organic alkoxysilyl compound. Specific examples of these compounds are the same as those exemplified for the high refractive index layer. Specific examples of the constituent composition of the hard coat layer include the compositions described in JP-A Nos. 2002-144913, 2000-9908, WO 0/46617, and the like.

  The high refractive index layer can also serve as a hard coat layer. In such a case, it is preferable to form fine particles dispersed in the hard coat layer using the method described for the high refractive index layer.

  The hard coat layer can also serve as an antiglare layer (described later) provided with particles having an average particle size of 0.2 to 10 μm to provide an antiglare function (antiglare function).

  The film thickness of the hard coat layer can be appropriately designed depending on the application. The film thickness of the hard coat layer is preferably 0.2 to 10 μm, more preferably 0.5 to 7 μm.

  The strength of the hard coat layer is preferably H or higher, more preferably 2H or higher, and most preferably 3H or higher in a pencil hardness test according to JIS K5400. Further, in the Taber test according to JIS K5400, the smaller the wear amount of the test piece before and after the test, the better.

[Forward scattering layer]
When applied to a liquid crystal display device, the forward scattering layer is provided in order to give an effect of improving the viewing angle when the viewing angle is inclined in the vertical and horizontal directions. By dispersing fine particles having different refractive indexes in the hard coat layer, it can also serve as a hard coat function. For example, Japanese Patent Application Laid-Open No. 11-38208 specifying a forward scattering coefficient, Japanese Patent Application Laid-Open No. 2000-199809 having a relative refractive index of a transparent resin and fine particles in a specific range, and Japanese Patent Application Laid-Open No. 2002 specifying a haze value of 40% or more. A forward scattering layer described in JP-A-107512 can be used.

[Other layers]
In addition to the above layers, a primer layer, an antistatic layer, an undercoat layer, a protective layer, and the like may be provided.

[Coating method]
Each layer of the antireflection film is formed by a dip coating method, an air knife coating method, a curtain coating method, a roller coating method, a wire bar coating method, a gravure coating, a micro gravure method or an extrusion coating method (US Pat. No. 2,681,294). It can be formed by coating.

[Anti-glare function]
The antireflection film may have an antiglare function that scatters external light. The antiglare function is obtained by forming irregularities on the surface of the antireflection film. When the antireflection film has an antiglare function, the haze of the antireflection film is preferably 3 to 30%, more preferably 5 to 20%, and most preferably 7 to 20%.

  As a method for forming irregularities on the surface of the antireflection film, any method can be applied as long as these surface shapes can be sufficiently maintained. For example, a method of forming irregularities on the film surface using fine particles in the low refractive index layer (for example, JP 2000-271878 A), a lower layer of the low refractive index layer (high refractive index layer, medium refractive index layer) Alternatively, a relatively large particle (particle size 0.05 to 2 μm) is added to a hard coat layer in a small amount (0.1 to 50% by mass) to form a surface uneven film, and these shapes are maintained on it. A method of providing a low refractive index layer (for example, JP 2000-281410 A, JP 2000-95893 A, JP 2001-100004 A, 2001-281407, etc.), an uppermost layer (antifouling layer) After coating, a method of physically transferring the uneven shape onto the surface (for example, as an embossing method, described in JP-A-63-278839, JP-A-11-183710, JP-A-2000-275401, etc.) And the like.

  Specific embodiments of the cellulose acylate film-forming method and cellulose acylate film of the present invention are described below, but the present invention is not limited to these examples.

The measurement methods used in the examples of the present invention are described below.
(1) Residual solvent concentration A glass bottle capable of being sealed was prepared and weighed, and this mass was defined as W ₀ . After casting, about 15 cm ² of the cellulose acylate film was sampled at a predetermined time, immediately put into this glass bottle, stoppered, and weighed. The mass was W _1. Next, the stopper of the glass bottle was opened, and it was dried in a 140 ° C. air constant temperature bath for 2 hours. After drying and taking out, it was immediately plugged, allowed to cool in a desiccator for 30 minutes, and weighed. This mass was designated as W ₃ .
The residual solvent concentration (mass%) was calculated from the following formula.
Residual solvent concentration (% by mass) = (W ₁ −W ₃ ) / (W ₃ −W ₀ ) × 100

(2) Elastic Modulus After casting the dope, it was dried for a predetermined time, peeled off from the casting support, and immediately subjected to tensile measurement under the following conditions to obtain the elastic modulus.
Between chucks: 180mm
Sample width: 35mm
Tensile speed: 83 mm / sec The modulus of elasticity is obtained by dividing the force by the cross-sectional area, and the thickness and width of the film were obtained by measurement immediately after peeling.

(3) XD
Since it cannot be measured with an actual casting machine, it is measured by casting on a glass plate using a doctor blade. However, the casting dope, the drying conditions, etc. were carried out so as to be the same as the actual casting machine.
What was dried for a predetermined time was subjected to XD measurement under the following conditions.
Measurement range: 2θ = 5-30 °
Scanning speed: 5 ° / min Light source: CuKα ray (30 kV, 100 mA)
The strength and peak top were determined by the following method.
Intensity: The height from the base line of the maximum peak appearing at 2θ = 5 to 14 ° (a line connecting 5 ° and 14 ° with a straight line) was determined.
Peak top: position of the maximum peak appearing at 2θ = 5-14 ° (2θ)
(4) HV Scattering Intensity, VV Scattering Intensity Measured by using “Polymer film dynamic analyzer DYNA-3000” manufactured by Otsuka Electronics.
The HV scattering intensity was measured by making the absorption axes of the polarizers installed on the incident light side and the detector side orthogonal to each other, and the VV scattering intensity was measured by making these parallel. These measurements are performed as a two-dimensional image using a CCD camera as a detector. In the present invention, the incident light is used as an axis over a scattering angle of 2 to 20 °, and one round (360 °) is integrated on the projection surface. Refers to the averaged value.
Since this measurement cannot be performed in an actual casting machine, the measurement was performed after casting using a doctor blade on a glass plate as a model and drying for a predetermined time. However, the casting dope, the drying conditions, etc. were carried out so as to be the same as the actual casting machine.

(5) Shaking method The pendulum type viscoelasticity measuring device (Rheovibron DDV-OPA type manufactured by Orientec Co., Ltd.) was used to measure using a pendulum having a diameter of 1 mmφ.
Since this measurement cannot be performed in an actual casting machine, the measurement was performed after casting using a doctor blade on a glass plate as a model and drying for a predetermined time. However, the casting dope, the drying conditions, etc. were carried out so as to be the same as the actual casting machine.

(6) Measurement of infrared absorption spectrum (IR) Since this measurement cannot be performed in an actual casting machine, it is cast using a doctor blade on a measuring device (ATR-IR) as shown below. Measured after drying for a predetermined time. However, the casting dope, the drying conditions, etc. were carried out so as to be the same as the actual casting machine.
A dope was cast on the Ge crystal plate of a single reflection type ATR-IR measuring apparatus (Spectratech Thunder Dome) so as to be the same as the conditions of a predetermined casting machine. Thereafter, the measurement was integrated 30 times at 1 minute intervals and displayed as absorbance. The background was measured with an ATR-IR apparatus before casting the dope.
The peak tops of 1030 to 1070 cm ⁻¹ and 1740 to 1760 cm ⁻¹ were obtained by detecting the peak at the maximum absorbance in these ranges.
Half-width, when the peak of 1030~1070cm ^-1, 1200 ± 10cm ^-1, from connecting it baseline straight respective lowest absorbance in the 970 ± 10 cm ^-1, make a vertical line, the peak of its midpoint The width was determined. On the other hand, if the peak of 1740～1760Cm ^-1, a line that runs on 1900 cm ^-1 and 1550 cm ^-1 and a baseline, was measured in the same manner.
In addition, the dope to be used was different from that used in a casting machine, and the one in which the solvent was changed to dichloromethane was used. This is because the IR signal of solvents such as methyl acetate and alcohol overlap with the signal of cellulose acylate. Even if the solvent is changed in this way, information reflecting the structure formation of the amorphous part can be obtained if the drying conditions are adjusted as described above.

(7) Viscosity Viscoelasticity was measured under the following conditions using a viscoelasticity measuring device (CVO-10 type: manufactured by Borin).
(A) Cone: 40 mmφ, parallel plate, gap = 500 μm
(B) Put a glass cover on the cone and seal it. In addition, the rotating shaft of the cone is sealed with a dope solvent (to prevent the solvent in the dope from evaporating during measurement and the viscosity from fluctuating).
(C) In cooling, a constant refrigerant is passed from the constant temperature circulation tank to the measurement unit (jacket under the cone) to keep the measurement temperature constant.
(D) Measurement is carried out by measuring the viscosity 20 times at 25 ° C., strain = 1%, frequency = 1 Hz (unit = Pa · s), and obtaining the average value.

(8) Degree of substitution of cellulose acylate The degree of acyl substitution at the 2-position, 3-position and 6-position of cellulose acylate was determined by 13C-NMR according to the method described in Carbohydr. Res. 273 (1995) 83-91 (Tezuka et al.). Determined by

(9) Degree of polymerization of cellulose acylate (DP)
About 0.2 g of completely dried cellulose acylate was precisely weighed and dissolved in 100 ml of a mixed solvent of methylene chloride: ethanol = 9: 1 (mass ratio). This was measured with an Ostwald viscometer for the number of seconds dropped at 25 ° C., and the degree of polymerization was determined by the following equation.
ηrel = T / T ₀
[Η] = (1nηrel) / C
DP = [η] / Km

Here, T is the falling seconds of the measurement sample, T ₀ is the falling seconds of the solvent alone, C is the dope concentration (g / l), and Km is 6 × 10 ⁻⁴ .

(Example 1 and Comparative Example 1)
1. Formation of Cellulose Acylate Film (1) Preparation of Cellulose Acylate Cellulose acylates with different types of acyl groups and different degrees of substitution described in Table 1 were prepared. In this, sulfuric acid (7.8 parts by mass with respect to 100 parts by mass of cellulose) was added as a catalyst, a carboxylic acid serving as a raw material for the acyl substituent was added, and an acylation reaction was performed at 40 ° C. At this time, the type of acyl group and the degree of substitution were adjusted by adjusting the type and amount of carboxylic acid. Moreover, it age | cure | ripened at 40 degreeC after acylation. The degree of polymerization of the cellulose acylate thus obtained was 290 to 320.

(2) Preparation of dope (a) Solvent Selected from the following solvents and listed in Table 1.
(I) Non-chlorine type: methyl acetate / acetone / methanol / ethanol / butanol (81/8/7/6 parts by mass)
(B) Chlorine: dichloromethane / methanol / ethanol / butanol (75/10/5/5/5 parts by mass)
(B) Cellose acylate After drying to a water content of 0.5% by mass or less, the cellulose acylate shown in Table 1 was adjusted to 15% by mass with respect to the solvent.
(C) Additive (I) Plasticizer A: Triphenyl phosphate (8% by mass)
(B) Plasticizer B: Biphenyl diphenyl phosphate (4% by mass)
(C) UV agent a: 2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-tert-butylanilino) -1,3,5-triazine (1% by mass)
(D) UV agent b: 2 (2′-hydroxy-3 ′, 5′-di-tert-butylphenyl) -5-chlorobenzotriazole (1% by mass)
(E) UV agent c: 2 (2′-hydroxy-3 ′, 5′-di-tert-amylphenyl) -5-chlorobenzotriazole (1% by mass)
(F) Fine particles: silicon dioxide (particle diameter 20 nm), Mohs hardness of about 7 (0.25 mass%)
(G) Citric acid ethyl ester (1: 1 mixture of monoester and diester, 0.2% by mass)
In addition, all the said addition amount (mass%) is a ratio with respect to a cellulose acylate.
(D) Swelling The cellulose acylate and the additive were added to the solvent while stirring. When the addition was completed, stirring was stopped and the slurry was swelled at 25 ° C. for 3 hours to prepare a slurry.
(E) Dissolution Using the apparatus shown in FIG. 1 of JP-A-10-324774, this slurry was introduced into a kneader equipped with a cooling jacket and dissolved. The temperature at this time was −70 ° C., and the residence time was 30 minutes. The dope taken out from the kneader was heated to room temperature while passing through a kneader similarly provided with a temperature control jacket.
(F) Filtration / concentration Thereafter, the mixture is filtered with a filter paper having an absolute filtration accuracy of 0.01 mm (manufactured by Toyo Filter Paper Co., Ltd., # 63), and further filtered with a filter paper having an absolute filtration accuracy of 2.5 μm (FH025, manufactured by Paul) Filtered. The obtained dope was heated under pressure at 110 ° C. and 1 MPa, and then released to normal pressure (about 0.1 Mpa) to volatilize the organic solvent to obtain a dope having a cellulose triacetate concentration of 24 mass%. Furthermore, while stirring this solution well, 2% by weight of butanol was gradually added to the solid content of cellulose triacetate to obtain a uniform solution.
(G) Decrease in viscosity Thereafter, the alcohol described in Table 1 was added to the dope (mass% with respect to the total amount of the dope). The viscosity of the dope before and after the addition was measured by the above method, and the decrease in viscosity was determined according to the following formula.

    Viscosity reduction (%) = 100 × {(dope viscosity before addition) − (dope viscosity after addition)} / (dope viscosity before addition)

(3) Formation of Cellulose Triacetate Film The above-mentioned dope was heated to 50 ° C. and cast on a mirror surface stainless steel support having a band length of 60 m through a casting Giesser. The Gieseer used was similar to that described in Japanese Patent Application Laid-Open No. 11-314233. The casting speed was 60 m / min and the casting width was 250 cm. Table 1 shows the blowing air temperature and wind speed on the surface side (dope side) on the stainless steel support, the temperature difference between the support side and the surface, and the temperature difference support between the casting part and the stripping part on the support side. Further, a spot heater was used in the drying zone on the support to give the temperature fluctuations shown in Table 1. All of these times were 10 seconds.
After peeling off, the residual solvent was dried at a speed of 200% to 30% by mass shown in Table 1, and then dried at 110 ° C. for 5 minutes and further at 145 ° C. for 10 minutes to obtain a cellulose triacylate film (film). A thickness of 80 μm) was obtained. The obtained sample was trimmed at both ends by 3 cm, and then a knurling having a height of 100 μm was applied to a portion 2 to 10 mm from both ends, and wound into a 3000 m roll.
Comparative Example 18 was prepared by a method similar to that described in Example 1 of JP-A-2003-55476.

Table 2 shows XD, HV and VV scattering intensities in the drying process of the film obtained by the above measurement method, attenuation rate Δ by shaking method, peak top by IR measurement, full width at half maximum and increase / decrease in their shift. And elastic modulus, respectively.

Further, Re unevenness, Rth unevenness, and optical axis deviation of the obtained film were measured by the following methods.
(A) The sample film was conditioned at 25 ° C. and 60% RH for 3 hours or more.
(B) Using an automatic birefringence meter (KOBRA-21ADH / PR: manufactured by Oji Scientific Instruments Co., Ltd.), the wavelength from the direction perpendicular to the sample film surface, + 40 ° direction, and −40 ° direction at 25 ° C. and 60% RH The retardation value at 550 nm was measured. Rth was calculated from these three points. Further, the measured value in the vertical direction was defined as Re. At the same time, the slow axis was detected, and the angle formed by this angle and the casting axis was defined as the deviation of the optical axis.
(C) A point equally divided into 10 in the width direction was measured 10 times every 10 m in the longitudinal direction, and the difference between the maximum value and the minimum value among these 100 points was defined as Re unevenness, Rth unevenness, and optical axis deviation. .

  Table 3 shows the measurement results. In addition, the number of occurrences in 3000 m is shown in Table 3 through visual evaluation through a polarizing plate having orthogonally arranged creases caused by flapping during conveyance.

From Tables 1 to 3, the cellulose acylate film obtained by the production method of the present invention had an Re unevenness and an Rth unevenness of 2 nm or less, an optical axis deviation of 1 ° or less, and a crease of 2 or less. On the other hand, the cellulose acylate film of the comparative example had Re unevenness and Rth unevenness of 5 nm or more, an optical axis deviation of 4 ° or more, and a crack of 4 or more.
From this, it can be seen that the cellulose acylate film of the present invention is a good cellulose acylate film with little optical unevenness even when cast at high speed and high width.

(Example 2)
According to Example 1 of the Japan Society for Invention and Innovation Technical Report (Public Technical Number 201-1745), three-layer co-casting was performed using the dope. As in Example 1, good results were obtained.

(Example 3)
Cellulose acylate films having a film thickness of 40 μm, 100 μm and 120 μm were prepared in the same manner as in Example 1, and the physical properties of each were measured. Similar to Example 1, good performance was obtained.

Example 4
1. In preparing a saponified polarizing plate of a cellulose acylate film, the cellulose acylate film obtained in Example 1 was subjected to a surface treatment by saponification. The saponification method was performed by one of the following methods. Table 2 shows the saponification method.
(1) Coating saponification
20 parts by mass of water is added to 80 parts by mass of iso-propanol, and KOH is dissolved in this to a concentration of 1.5 mol / liter (1.5 N), and the temperature is adjusted to 60 ° C. as a saponification solution. It was. This was coated on a cellulose acylate film at 60 ° C. at 10 g / m ² and saponified for 1 minute. After that, using a spray with warm water of 50 ° C., washing was performed by spraying at 10 liter / m ² · min for 1 minute.
(2) Immersion saponification A 1.5 mol / liter (1.5N) aqueous solution of NaOH was used as a saponification solution. The temperature was adjusted to 60 ° C., and the cellulose acylate film was immersed for 2 minutes. Thereafter, the film was immersed in a 0.05 mol / liter (0.1N) sulfuric acid aqueous solution for 30 seconds and then passed through a water washing bath.

2. Production of Polarizing Plate (1) Production of Polarizing Layer A polarizing layer having a thickness of 20 μm was prepared by one of the following methods (described in Table 3).
(A) Diagonal Stretching Method According to Example 1 of JP-A-2002-86554, stretching was performed using a tenter so that the stretching axis became 45 ° obliquely.
(B) Parallel Stretching Method According to Example 1 of Japanese Patent Laid-Open No. 2001-141926, a circumferential speed difference was given between two pairs of nip rolls and stretched in the longitudinal direction.
(2) Bonding The polarizing layer thus obtained and the saponified cellulose acylate film were bonded to a polarizing axis and cellulose acylate using PVA (PVA-117H, Kuraray Co., Ltd.) 3% aqueous solution as an adhesive. The films were laminated so that the longitudinal direction of the film was 45 °.
All the polarizing plates using the cellulose acylate film satisfying the conditions of the present invention showed good performance.

(Example 5)
Production of Optical Compensation Film When the cellulose acylate film obtained in the present invention was used for the first transparent support of Example 1 of JP-A-11-316378, a good optical compensation film could be produced.
Also, an optical compensation filter film was produced by changing the cellulose triacetate manufactured by Fuji Photo Film Co., Ltd. used in Example 1 of JP-A-7-333433 to the cellulose acylate film of the present invention. The obtained filter film had an excellent viewing angle in the left, right, up and down directions.

(Example 6)
Production of Low Reflective Film When the cellulose acylate film of the present invention was produced using the cellulose acylate film of the present invention in accordance with Example 47 of the Japan Institute of Invention and Technology (Publication No. 2001-1745), a good result was obtained. Optical performance was obtained.

(Example 7)
Production of Liquid Crystal Display Element The above polarizing plate produced using the cellulose acylate film of the present invention was used as the liquid crystal display device described in Example 1 of JP-A-10-48420, and in Example of JP-A-9-26572. 1, an optically anisotropic layer containing discotic liquid crystal molecules, an alignment film coated with polyvinyl alcohol, a 20-inch VA liquid crystal display device described in FIGS. 2 to 9 of JP-A-2000-154261, A liquid crystal display element was produced using a 20-inch OCB type liquid crystal display device described in FIGS. Furthermore, the said low reflection film produced using the cellulose acylate film of this invention was affixed on the outermost layer of these liquid crystal display elements, and the following evaluation was performed. The results are shown in Table 3.

<Evaluation method>
A set of 100 liquid crystal display elements arbitrarily sampled from the longitudinal direction and width direction of the original cellulose acylate film was taken out immediately after 60 hours at 60 ° C., and the image display unevenness was evaluated with the naked eye. The display nonuniformity generation region of the liquid crystal display element in which the largest nonuniformity occurred was shown as a percentage. That is, the unevenness of the cellulose acylate film was evaluated over a wide range in the longitudinal direction and the width direction. The results are shown in Table 3.

As shown in Table 3, the liquid crystal display element using the cellulose acylate film of the present invention has a display unevenness of 1% or less in any type of liquid crystal display device of OCB type and VA type. In the liquid crystal display element using the film of the comparative example, display unevenness was 8 to 12%.
From this, it can be seen that a liquid crystal display device having excellent characteristics can be obtained by using the cellulose acylate film of the present invention.

  A liquid crystal display element was similarly prepared and evaluated using the above-described three-layer co-cast cellulose acylate film and cellulose acylate films having film thicknesses of 40 μm, 100 μm, and 120 μm. Similarly, good performance was obtained.

(Example 8)
Application to a silver halide photosensitive material support The cellulose acylate film of the present invention having a film thickness of 120 μm was used in Examples 63, 64 and 65 of the Association of the Invention of Invention (Publication No. 2001-1745). Even after (50 ° C., 500 hours), good performance was obtained.

  INDUSTRIAL APPLICABILITY The present invention can provide a method for producing a cellulose acylate film that hardly exhibits optical unevenness even when cast at high speed and wide width, and can be used as a substrate for liquid crystal display elements, silver halide photographic light-sensitive materials and the like. .

It is a figure which shows the measuring method of a shaking method.

Explanation of symbols

1 glass 2 dope 3 pendulum

Claims (10)

A method for producing a cellulose acylate film comprising the steps of casting a dope prepared by dissolving cellulose acylate with an organic solvent on a casting support from a casting die and drying to form a cellulose acylate film. ,
A dope having a viscosity reduced by 1 to 40% by adding 0.5 to 10% by weight of a poor solvent to 100 parts by weight of cellulose acylate is cast on a casting support,
The surface temperature of the cellulose acylate film is within the range of 20 to 70 ° C. by blowing air at 30 to 80 ° C. on the cellulose acylate film side of the casting support at a wind speed of 4 to 20 m / sec. Drying while adjusting the surface temperature on the casting support side to be 3 to 30 ° C. higher than the surface temperature on the opposite side, the elastic modulus of the cellulose acylate film is 6 to 6 when the residual solvent concentration is 100% by mass. When the residual solvent concentration is 50% by mass, the pressure is adjusted to be 10 to 20 MPa,
The cellulose acylate film is peeled off at the peeling portion where the temperature of the casting support is 1 to 30 ° C higher than the casting portion
A method for producing a cellulose acylate film, comprising drying the peeled cellulose acylate film within a range of 7.5 to 45C .   Adjusting the intensity of the X-ray diffraction spectrum (hereinafter referred to as “XD”) of CuKα rays of the cellulose acylate film having a residual solvent concentration of 300 mass% in the drying step to 200 to 1500 cps and 2θ of the XD peak top to 7 to 8 °. The method for producing a cellulose acylate film according to claim 1.   The XD strength of the cellulose acylate film having a residual solvent concentration of 20% by weight in the drying step is 100 to 3000 cps greater than the XD strength of the cellulose acylate film having a residual solvent concentration of 300% by weight, and the cellulose acylate having a residual solvent concentration of 20% by weight. The cellulose acylate according to claim 2, wherein the 2D at the peak top of the XD of the rate film is adjusted to be 0.1 to 2 ° larger than the 2θ at the peak top of the XD of the cellulose acylate film having a residual solvent concentration of 300% by mass. Film forming method. The VV scattering intensity of a cellulose acylate film having a residual solvent concentration of 300 to 45% by mass in the drying step is adjusted to 5 × 10 ^{−3 to} 5 × 10 ⁻¹ . The method for producing a cellulose acylate film according to one item. The production of the cellulose acylate film according to claim 4, wherein the HV scattering intensity of the cellulose acylate film having a residual solvent concentration of 300 to 45 mass% in the drying step is adjusted to 4 × 10 ⁻⁵ to 4 × 10 ⁻³ . Membrane method.   6. The maximum value of the attenuation rate [Delta] determined by the shaking method of a cellulose acylate film having a residual solvent concentration of 350 to 70% by mass in the drying step is adjusted to 0.05 to 0.5. The method for producing a cellulose acylate film according to any one of the above. Peak appearing in 1030～1070Cm ^-1 by infrared absorption spectroscopy in the drying step, at 1045～1050Cm ^-1 when dry start a peak top half width 46～54Cm ^-1, and the residue from the drying start solvent concentration of 20 wt% The peak top is shifted to 0.5 to 5 cm ^{-1 on the} low wavenumber side, and the half-value width is adjusted to increase by 0.5 to 10 cm ^-1. The method for producing a cellulose acylate film according to any one of the above. The drying peak appearing in 1740～1760Cm ^-1 by infrared absorption spectroscopy in step, in 1743～1749Cm ^-1 when dry start a peak top half width 28～38Cm ^-1, and the residual solvent concentration of 20 mass from the drying start The cellulose acylate according to claim 7, wherein the peak top is shifted to 0.5-5 cm ^{−1 on the} low wavenumber side and the half width is increased by 0.1-5 cm ⁻¹ during a period of up to 5%. A method for forming a film. The cellulose acylate film according to any one of claims 1 to 8 , wherein a cellulose acylate having a substitution degree with respect to a hydroxyl group of cellulose satisfying the following formulas (I) to (III) is used as the cellulose acylate. Membrane method.
(I) 2.6 ≦ SA + SB ≦ 3.0
(II) 1.5 ≦ SA ≦ 3.0
(III) 0 ≦ SB ≦ 0.8
[In the formulas (I) to (III), SA and SB represent the total degree of substitution with respect to the hydroxyl group of cellulose, SA represents the degree of substitution of the acetyl group, and SB represents substitution of the acyl group with 3 to 22 carbon atoms. Represents degrees. ] A claim using at least one solvent selected from non-chlorine organic solvents ethers having 3 to 12 carbon atoms, ketones having 3 to 12 carbon atoms and esters having 3 to 12 carbon atoms as the organic solvent. Item 10. A method for producing a cellulose acylate film according to any one of Items 1 to 9 .

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