JP5286114B2 - Cellulose acylate film and method for producing the same, polarizing plate and liquid crystal display device - Google Patents

Description

  The present invention relates to a cellulose acylate film, a method for producing the same, a polarizing plate, and a liquid crystal display device.

A liquid crystal display (LCD) includes a liquid crystal cell and a polarizing plate. The polarizing plate has a protective film (protective film) and a polarizing film. For example, the polarizing film is formed by dyeing and stretching a polarizing film made of polyvinyl alcohol with iodine, and attaching protective films on both sides thereof. In the transmissive liquid crystal display device, the polarizing plates are disposed on both sides of the liquid crystal cell, and one or more optical compensation films may be disposed. In a reflective liquid crystal display device, a reflector, a liquid crystal cell, one or more optical compensation films, and a polarizing plate are arranged in this order.
The liquid crystal cell includes a liquid crystal molecule, two substrates for encapsulating the liquid crystal molecule, and an electrode layer for applying a voltage to the liquid crystal molecule. The liquid crystal cell performs ON and OFF display depending on the alignment state of liquid crystal molecules, and can be applied to both transmissive and reflective liquid crystal display devices. TN (Twisted Nematic), IPS (In-Plane Switching) Display modes such as OCB (Optically Compensatory Bend), VA (Vertically Aligned), and ECB (Electrically Controlled Birefringence) have been proposed.

  The polarizing plate generally comprises a polarizing film and two transparent protective films provided on both sides thereof. The polarizing film is generally obtained by impregnating polyvinyl alcohol with an aqueous solution of iodine or a dichroic dye and further uniaxially stretching the film. A polarizing plate using a cellulose acylate film as a protective film has excellent optical properties, high transmittance and polarization degree in a wide wavelength range, and excellent brightness and contrast. It is also frequently used as a polarizing plate.

  Such a sheet-like material having optical functionality such as a polarizing plate and an optical compensation sheet is called an optical film, but as a transparent support of the optical film, it has excellent light transmittance and optical non-orientation. Thus, a cellulose acylate film represented by a cellulose acetate film having excellent physical and mechanical properties and having characteristics such as little dimensional change with respect to temperature and humidity changes is used.

  In the polarizing plate and the optical compensation sheet, a polarizing film and an optical compensation layer are provided on a cellulose acylate film of a transparent support via an adhesive layer and an alignment film (usually polyvinyl alcohol). As one means for providing adhesiveness to the surface, there is known a method (for example, Patent Documents 1 and 2) in which a cellulose acylate film is immersed in an alkaline aqueous solution to saponify and hydrophilize the surface.

  Conventionally, the cellulose acylate used in such a cellulose acylate film for an optical film has a high acyl group substitution degree of a hydroxyl group of a glucose unit in cellulose (hereinafter referred to as acyl group substitution degree). Triacetyl cellulose (TAC) having a substitution degree exceeding 2.70 and about 3 was used. However, in recent years, development of a film having further improved optical characteristics has been demanded. In response to such a demand, it is possible to develop a film having a new function by using diacetyl cellulose (DAC) having an acyl group substitution degree of about 2.7 or less as a cellulose acylate film for an optical film. This has become possible due to progress in method development.

However, although the saponification condition of the TAC cellulose acylate film described in Patent Document 1 is suggested to be suitable for a TAC cellulose acylate film having a high degree of acyl group substitution, it has a low degree of acyl group substitution. The application to the saponification treatment of the DAC-based cellulose acylate film, the TAC-based and DAC-based laminated films, and the problems at the time of application are not disclosed.
Patent Document 2 discloses a cellulose acetate propionate (CAP) film and a cellulose acetate butyrate (CAB) film having a certain low acyl group substitution degree of about 2.66 to 2.7. Although some examples of saponification treatment are disclosed, a detailed comparison with the case where the acyl group substitution degree is high is not made. That is, Patent Document 2 does not particularly examine the problem in saponifying a film containing cellulose acylate having a low acyl group substitution degree.

  For this reason, the saponification conditions for films containing cellulose acylate having a low acyl group substitution degree have not been sufficiently studied, and the development of efficient and effective saponification conditions has been demanded.

JP-A-7-151914 JP 2006-215535 A

  When the present inventor applied the saponification treatment method described in Patent Documents 1 and 2 to a film containing cellulose acylate having a low acyl group substitution degree, improvement in the surface condition of the film surface was demanded, and the polarizing film It was found that improvement was also required for the adhesion with the like. In particular, it was found that the surface condition of the film surface has problems of whitening (haze-up), shrinkage, crease and wrinkle. Moreover, when the film thus obtained was incorporated into a polarizing plate or a liquid crystal display device, there was also a problem that the phase difference variation was great under humid heat environment.

  That is, an object of the present invention is to provide a cellulose acylate film containing cellulose acylate having a low acyl group substitution degree, having a good surface shape after saponification treatment, and excellent adhesion to a polarizing film and the like, and a method for producing the same. There is to do.

  As a result of intensive studies, the present inventor has found that the above problems can be achieved by the following configuration.

[1] A cellulose acylate film characterized by containing a cellulose acylate which is saponified under the conditions represented by the following formulas (A-1) to (A-3) and satisfies the following formula (B) .
Formula (A-1): 25 ≦ T ≦ 45
(In the formula (A-1), T represents a saponification temperature (unit: ° C.).)
Formula (A-2): 0.5 ≦ S ≦ 5
(In the formula (A-2), S represents the saponification time (unit: minutes).)
Formula (A-3): 0.5 ≦ D ≦ 4.5
(In formula (A-3), D represents the alkali normality (unit: N) of the saponification solution.)
Formula (B): 2.0 ≦ DS ≦ 2.7
(In the formula (B), DS represents the acyl group substitution degree of the hydroxyl group of the glucose unit in cellulose.)
[2] The cellulose acylate film according to [1], having a laminate structure of 2 or more.
[3] At least one layer contains cellulose acylate satisfying the following formula (B),
The cellulose acylate according to [2], wherein at least one layer different from the layer containing the cellulose acylate satisfying the following formula (B) contains the cellulose acylate satisfying the following formula (C). Rate film.
Formula (B): 2.0 ≦ DS ≦ 2.7
Formula (C): 2.7 ≦ DS ≦ 3.0
(In formulas (B) and (C), DS represents the acyl group substitution degree of the hydroxyl group of the glucose unit in cellulose.)
[4] Cellulose acylate having a laminate structure of 3 or more, wherein at least one inner layer contains cellulose acylate satisfying the following formula (B), and both surface layers satisfy the following formula (C) The cellulose acylate film according to [2] or [3], which is contained.
Formula (B): 2.0 ≦ DS ≦ 2.7
Formula (C): 2.7 ≦ DS ≦ 3.0
(In formulas (B) and (C), DS represents the acyl group substitution degree of the hydroxyl group of the glucose unit in cellulose.)
[5] The cellulose acylate film according to any one of [2] to [4], wherein the film thickness of at least one surface layer is 0.5 to 5 μm.
[6] The cellulose acylate film according to any one of [1] to [5], which is formed by co-casting.
[7] Any one of [1] to [6], wherein the saponification treatment includes a saponification step using an alkaline saponification solution for promoting a saponification reaction, and a step of slowing or stopping the saponification reaction. The cellulose acylate film described.
[8] The cellulose acylate film according to [7], wherein the step of slowing or stopping the saponification reaction is a dilution step or a neutralization step.
[9] The ratio of the peak of 290 eV to the maximum peak in the vicinity of 288 eV is 0.50 or less in the carbon (C1s) spectrum when measuring at least one surface by X-ray photoelectron spectroscopy [1] ] The cellulose acylate film as described in any one of [8].
[10] The cellulose acylate film according to any one of [1] to [9], wherein the contact angle of water on the surface of at least one side is less than 50 °.
[11] The cellulose acylate film according to any one of [1] to [10], wherein the haze is 1.0% or less.
[12] The front retardation value Re (590) at a wavelength of 590 nm and the retardation value Rth (590) in the film thickness direction at a wavelength of 590 nm satisfy the following formulas (I) and (II): [1] The cellulose acylate film according to any one of to [11].
Formula (I): 30 nm ≦ Re (590) ≦ 70 nm
Formula (II): 80 nm ≦ Rth (590) ≦ 250 nm
[13] A cellulose acylate film containing a cellulose acylate satisfying the following formula (B) is saponified under conditions satisfying the following formulas (A-1) to (A-3): A method for producing a cellulose acylate film.
Formula (A-1): 25 ≦ T ≦ 45
(In the formula (A-1), T represents a saponification temperature (unit: ° C.).)
Formula (A-2): 0.5 ≦ S ≦ 5
(In the formula (A-2), S represents the saponification time (unit: minutes).)
Formula (A-3): 0.5 ≦ D ≦ 4.5
(In formula (A-3), D represents the alkali normality (unit: N) of the saponification solution.)
Formula (B): 2.0 ≦ DS ≦ 2.7
(In the formula (B), DS represents the acyl group substitution degree of the hydroxyl group of the glucose unit in cellulose.)
[14] The method for producing a cellulose acylate film according to [13], wherein the cellulose acylate film before the saponification treatment has two or more laminated structures.
[15] At least one layer of the cellulose acylate film before the saponification treatment contains a cellulose acylate satisfying the following formula (B), and is different from the layer containing the cellulose acylate satisfying the following formula (B). The method for producing a cellulose acylate film according to [14], wherein at least one of the layers contains cellulose acylate satisfying the following formula (C).
Formula (B): 2.0 ≦ DS ≦ 2.7
Formula (C): 2.7 ≦ DS ≦ 3.0
(In formulas (B) and (C), DS represents the acyl group substitution degree of the hydroxyl group of the glucose unit in cellulose.)
[16] The cellulose acylate film before saponification treatment has a laminated structure of 3 or more, at least one inner layer contains cellulose acylate satisfying the following formula (B), and both surface layers are: Cellulose acylate satisfying formula (C) is contained, [14] or [15], The method for producing a cellulose acylate film according to [15].
Formula (B): 2.0 ≦ DS ≦ 2.7
Formula (C): 2.7 ≦ DS ≦ 3.0
(In formulas (B) and (C), DS represents the acyl group substitution degree of the hydroxyl group of the glucose unit in cellulose.)
[17] The cellulose according to any one of [14] to [16], wherein a film thickness of at least one surface layer of the cellulose acylate film before the saponification treatment is 0.5 to 5 μm. A method for producing an acylate film.
[18] The method for producing a cellulose acylate film according to any one of [13] to [17], wherein the cellulose acylate film before the saponification treatment is formed by co-casting.
[19] Any one of [13] to [18], wherein the saponification treatment includes a saponification step using an alkaline saponification solution that causes the saponification reaction to proceed and a step of slowing or stopping the saponification reaction. The manufacturing method of the cellulose acylate film of description.
[20] The method for producing a cellulose acylate film according to [19], wherein the step of slowing or stopping the saponification reaction is a dilution step or a neutralization step.
[21] A cellulose acylate film produced by the method for producing a cellulose acylate film according to any one of [13] to [20].
[22] In the polarizing plate in which a protective film is bonded to both sides of the polarizer, at least one of the protective films is the cellulose acylate film according to any one of [1] to [12] and [21]. A polarizing plate characterized by the above.
[23] A liquid crystal display device having the polarizing plate according to [22].
[24] The liquid crystal display device according to [23], which is in a VA mode.

  Although the cellulose acylate film of the present invention contains cellulose acylate having a low acyl group substitution degree, it does not cause whitening, shrinkage, crease or wrinkle after saponification treatment, and has a good surface shape. Moreover, it is excellent also in adhesiveness with a polarizing film etc. Furthermore, according to the method for producing a cellulose acylate film of the present invention, such a cellulose acylate film can be provided. In addition, the polarizing plate of the present invention using the cellulose acylate film of the present invention has a small change in the degree of polarization with respect to heat and humidity and is excellent in durability. Therefore, the liquid crystal display device of the present invention exhibits excellent display performance.

Hereinafter, the cellulose acylate film of the present invention and the production method thereof will be described in detail.
The description of the constituent elements described below may be made based on typical embodiments of the present invention, but the present invention is not limited to such embodiments. In the present specification, a numerical range represented by using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.

[Cellulose acylate film]
The cellulose acylate film of the present invention (hereinafter also referred to as the film of the present invention) is saponified under the conditions represented by the following formulas (A-1) to (A-3) and satisfies the following formula (B). It contains cellulose acylate.
Formula (A-1): 25 ≦ T ≦ 45
(In the formula (A-1), T represents a saponification temperature (unit: ° C.).)
Formula (A-2): 0.5 ≦ S ≦ 5
(In the formula (A-2), S represents the saponification time (unit: minutes).)
Formula (A-3): 0.5 ≦ D ≦ 4.5
(In formula (A-3), D represents the alkali normality (unit: N) of the saponification solution.)
Formula (B): 2.0 ≦ DS ≦ 2.7
(In the formula (B), DS represents the acyl group substitution degree of the hydroxyl group of the glucose unit in cellulose.)
Hereinafter, the present invention will be specifically described with reference to preferred embodiments of the present invention.

(Cellulose acylate)
The cellulose acylate used in the present invention is not particularly defined except that it contains at least cellulose acylate in which the substitution degree of all acyl groups satisfies the formula (B). Examples of the acylate raw material cellulose include cotton linter and wood pulp (hardwood pulp, conifer pulp). Cellulose acylate obtained from any raw material cellulose can be used, and in some cases, it may be mixed and used. Detailed descriptions of these raw material celluloses can be found in, for example, Marusawa and Uda, “Plastic Materials Course (17) Fibrous Resin”, published by Nikkan Kogyo Shimbun (published in 1970), and the Japan Society of Invention and Innovation Technical Bulletin No. 2001. The cellulose described in No.-1745 (pages 7 to 8) can be used.

First, the cellulose acylate preferably used in the present invention will be described in detail. 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 an acyl group having 2 or more carbon atoms. The degree of acyl substitution means the ratio of the cellulose hydroxyl groups located at the 2nd, 3rd and 6th positions being esterified (100% esterification has a degree of substitution of 1).
DS6 / (DS2 + DS3 + DS6) is preferably 0.08 to 0.66, more preferably 0.15 to 0.60, and still more preferably 0.20 to 0.45. Here, DS2 is the degree of substitution of the hydroxyl group at the 2-position of the glucose unit with an acyl group (hereinafter also referred to as “degree of acyl substitution at the 2-position”), and DS3 is the degree of substitution of the hydroxyl group at the 3-position with an acyl group (hereinafter, referred to as “acyl group”). DS6 is the substitution degree of the hydroxyl group at the 6-position with an acyl group (hereinafter also referred to as “acyl substitution degree at the 6-position”). DS6 / (DS2 + DS3 + DS6) is the ratio of the acyl substitution degree at the 6-position to the total acyl substitution degree, and is hereinafter also referred to as “acyl substitution ratio at the 6-position”.

Only one type of acyl group may be used in the inner layer of the film of the present invention, or two or more types of acyl groups may be used. The film of the present invention preferably has an acyl group having 2 to 4 carbon atoms as a substituent. When two or more types of acyl groups are used, one of them is preferably an acetyl group, and the acyl group having 2 to 4 carbon atoms is preferably a propionyl group or a butyryl group. When two or more types of acyl groups are used, the sum of the substitution degrees of the hydroxyl groups at the 2-position, 3-position and 6-position by the acetyl group is DSA, and the hydroxyl groups at the 2-position, 3-position and 6-position are based on the propionyl group or butyryl group. When the total degree of substitution is DSB, the DSA + DSB value of at least one cellulose acylate used in the film of the present invention is preferably 2.0 to 2.7. The DSA + DSB value is preferably 2.1 to 2.65, and the DSB value is more preferably 0.10 to 1.70, and still more preferably the DSA + DSB value is 2.2 to 2.60, and the DSB value. Is 0.6 to 1.7. It is preferable that the DSA and DSB values be within the above ranges because a film having a small change in Re value and Rth value due to environmental humidity can be obtained.
Furthermore, it is preferable that 28% or more of the DSB is a substituent at the 6-position hydroxyl group, more preferably 30% or more is a substituent at the 6-position hydroxyl group, and 31% or more is a substituent at the 6-position hydroxyl group. Is more preferable, and in particular, it is also preferable that 32% or more is a substituent of the 6-position hydroxyl group. With these films, a solution having a preferable solubility can be prepared, and in particular, in a non-chlorine organic solvent, a good solution can be prepared. Furthermore, it becomes possible to produce a solution having a low viscosity and good filterability.

  The acyl group having 2 or more carbon atoms of the cellulose ester in the present invention may be an aliphatic group or an allyl group, and is not particularly limited. These are, for example, cellulose alkylcarbonyl esters, alkenylcarbonyl esters, aromatic carbonyl esters, aromatic alkylcarbonyl esters, and the like, each of which may further have a substituted group. Preferred examples thereof include propionyl, butanoyl, heptanoyl, hexanoyl, octanoyl, decanoyl, dodecanoyl, tridecanoyl, tetradecanoyl, hexadecanoyl, octadecanoyl, isobutanoyl, tert -A butanoyl group, a cyclohexanecarbonyl group, an oleoyl group, a benzoyl group, a naphthylcarbonyl group, a cinnamoyl group, etc. can be mentioned. Among these, a propionyl group, a butanoyl group, a dodecanoyl group, an octadecanoyl group, a tert-butanoyl group, an oleoyl group, a benzoyl group, a naphthylcarbonyl group, a cinnamoyl group, and the like are more preferable, and a propionyl group and a butanoyl group are particularly preferable. is there.

  In the acylation of cellulose, when an acid anhydride or acid chloride is used as an acylating agent, an organic acid such as acetic acid or methylene chloride is used as an organic solvent as a reaction solvent.

As the catalyst, when the acylating agent is an acid anhydride, a protic catalyst such as sulfuric acid is preferably used, and when the acylating agent is an acid chloride (for example, CH ₃ CH ₂ COCl), Basic compounds are used.

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

  The cellulose ester used in the present invention can be synthesized, for example, by the method described in JP-A-10-45804.

(Layer structure of cellulose acylate film)
The film of the present invention may have a single layer structure or a laminate structure of two or more as long as at least one layer contains cellulose acylate satisfying the formula (B). In the case of a laminated structure, the acyl substitution degree of cellulose acylate in each layer may be uniform, or a plurality of cellulose acylates may be mixed in one layer, but cellulose acylate in each layer It is preferable from the viewpoint of adjustment of optical properties that the degree of acyl group substitution is constant. When the cellulose acylate satisfying the above formula (B) is used, the film of the present invention has a single layer structure or a laminated structure of two or more, the physical properties of the film after saponification treatment, One of the characteristics is that the surface of the film is particularly excellent. Conventionally, conditions for saponifying a film containing cellulose acylate (so-called DAC) having such a low acyl group substitution degree are disclosed in Table 1 of Examples of Japanese Patent Application Laid-Open No. 2006-215535. Under the conditions described in the literature, there were problems such as whitening and wrinkles. Furthermore, in this invention, when the acyl group substitution degree of DAC is further reduced from 2.66-2.7 described in the examples of JP-A-2006-215535, that is, when the moisture content of the film is further increased. Even so, it is possible to provide a film that is suitably saponified.

  It is preferable that the film of the present invention has two or more laminated structures from the viewpoint of improving the film surface and productivity, and improving the film transparency accompanying the reduction of the matting agent.

In the film of the present invention, at least one layer contains cellulose acylate satisfying the formula (B), and at least one layer different from the layer containing cellulose acylate satisfying the formula (B) is It is preferable to contain cellulose acylate satisfying the formula (C) from the viewpoint of improving productivity.
Formula (C): 2.7 ≦ DS ≦ 3.0
(In formula (C), DS represents the acyl group substitution degree of the hydroxyl group of the glucose unit in cellulose.)

The film of the present invention preferably has a laminate structure of 3 or more from the viewpoint of curling amount reduction due to environmental moist heat change.
The film of the present invention has a laminate structure of 3 or more, at least one inner layer contains cellulose acylate satisfying the formula (B), and both surface layers have the formula (C). It is preferable that the cellulose acylate to be filled is contained from the viewpoint of improving the degree of freedom of the process for realizing desired optical characteristics as an optical compensation film. Furthermore, the film of the present invention has a laminate structure of 3 or more, and the cellulose acylate contained in at least one inner layer is a cellulose acylate satisfying the formula (B), and the surface layers on both sides The cellulose acylate contained is more preferably a cellulose acylate satisfying the formula (C). In the present specification, a layer in which all the cellulose acylates contained in one layer are cellulose acylates satisfying the formula (B) may be referred to as a DAC layer, and the cellulose acylate contained in one layer may be referred to as a DAC layer. A layer in which the rate is cellulose acylate satisfying the formula (C) may be referred to as a TAC layer.
In particular, when the film of the present invention has a laminated structure in which both surfaces of a cellulose acylate layer having a low acyl group substitution degree are covered with a surface layer of a cellulose acylate having a high acyl group substitution degree, the conventional TAC is used. It is assumed optimal to use optimized stringent saponification conditions. However, it has been found that under the strict saponification conditions for conventional TAC, the saponification progresses quickly and the surface condition deteriorates. Thus, it was found that by setting weaker saponification conditions, particularly milder temperature conditions, a film having such a laminated structure can be suitably saponified.

  Moreover, it is more preferable that the film of the present invention has a three-layer structure. When the film of the present invention has a three-layer structure, the structure may be a TAC layer / DAC layer / TAC layer or a DAC layer / TAC layer / DAC layer. The structure of the / TAC layer is preferable from the viewpoint of curling amount reduction due to changes in environmental moisture and heat, and improvement in the degree of freedom of process for realizing desired optical characteristics as an optical compensation film.

In the film of the present invention, the film thickness of at least one surface layer is preferably 0.5 to 5 μm. When the film thickness of the surface layer is 0.5 μm or more, it is preferable that variations in the film thickness distribution in the width direction of the surface layer hardly occur and variations in optical characteristics become small. Further, it is preferable that the thickness of the surface layer is 5 μm or less because the ratio of the thickness of the surface layer to the thickness of the entire laminated structure is sufficiently small and the optical characteristics of the inner layer can be sufficiently expressed. The film thickness of at least one surface layer is more preferably 0.8 to 4 μm, and further preferably 1.0 to 3 μm.
When the film of the present invention has a laminate structure of 3 or more, it is more preferable that the film thicknesses of the surface layers on both sides of the film are both 0.5 to 5 μm, more preferably 0.8 to 4 μm. More preferably, it is 0.0-3 micrometers.
When the film thickness of the surface layer is thin as described above, a saponification solution (for example, an alkali solution) is likely to penetrate into the inner layer by saponification treatment. Since the film of the present invention is subjected to a preferred saponification treatment in the method for producing a cellulose acylate film of the present invention, which will be described later, even if the saponification solution penetrates into the inner layer, haze-up (whitening) hardly occurs.

The film of the present invention has a film thickness of preferably 30 to 80 μm, more preferably 35 to 70 μm, regardless of whether the film has a laminated structure or a single layer structure. It is particularly preferable that the thickness is ˜60 μm.
Moreover, when the film of this invention has a laminated structure of 3 or more, it is preferable that the film thickness of an internal layer (preferably DAC layer) is 28-78 micrometers, It is more preferable that it is 33-68 micrometers, 38-58 micrometers It is particularly preferred that

As one of the preferred embodiments of the present invention, it has a laminated structure of 3 or more, has a DAC layer as an internal layer, and is thinner than the internal layer (preferably both 0.5 to 5 μm, more preferably (Conditions are as described above) A laminated structure having a TAC layer as an external layer can be mentioned. The film of the present invention is characterized in that even if it is an embodiment having such a thin TAC layer as an outer layer, the TAC layer of the outer layer is appropriately saponified and has an excellent surface shape. In the above preferred embodiment of the present invention, the film of the present invention has the characteristics of excellent surface condition after saponification and low haze as compared with the case where the film of the present invention has a single-layer structure consisting of only a DAC layer. However, according to the method for producing the film of the present invention described later, the saponification treatment can be suitably carried out even with the laminated structure film of the preferred embodiment of the present invention, and the film of the present invention can be obtained. Specifically, the conventional saponification conditions for DAC and the strict saponification conditions for conventional TAC have a problem that the saponification progresses quickly and the surface condition deteriorates. Weaker saponification conditions, especially milder temperature conditions are set. As a result, it was found that the film having a laminated structure according to the preferred embodiment of the present invention can be saponified.
The film of the present invention has a laminate structure of 3 or more, has a DAC layer as an internal layer, and has a film thickness thinner than the internal layer (preferably both 0.5 to 5 μm, and more preferable conditions are the above In the case of a laminated structure having a TAC layer as an external layer, the type and amount of addition of the retardation adjusting agent to be described later can be controlled independently in the DAC layer and the TAC layer. The range of preferable retardation values to be described can be easily achieved.

(XPS ratio)
The film of the present invention after saponification is characterized by the following surface characteristics.
In the carbon (C1s) spectrum when the surface of at least one side after the saponification treatment of the optical film is measured by X-ray photoelectric spectroscopy (ESCA), the peak ratio between the maximum peak of 288 eV and the peak of 290 eV (hereinafter also referred to as XPS ratio) However, it is preferable that it is 0.50 or less from a viewpoint of adhesive improvement. The peak ratio is more preferably 0.15 to 0.45. The carbon (C1s) spectrum of the hydrophilized surface can be known by using, for example, a photoelectron spectrometer {“ESCA3400” type, manufactured by Shimadzu Corporation].

When the XPS ratio is 0.50 or less, the surface is sufficiently hydrophilic, and adhesion and the like are improved in the polarizing plate and the optical compensation film using the optical film of the present invention. On the other hand, when the ratio is larger than 0.15, the saponification reaction does not proceed excessively, and the original optical performance and / or physical performance of the cellulose acylate film produced according to the present invention can be sufficiently exhibited.
The XPS ratio is based on knowledge as a chemical shift of the carbon spectrum of X-ray photoelectric spectroscopy (ESCA), and the maximum peak near 288 eV is derived from a C = O signal (derived from an acyl group of a cellulose ester). ) And a peak at 290 eV can be calculated as a C—O signal (derived from a hydroxyl group of cellulose).

(Water contact angle)
The film of the present invention after the saponification treatment preferably has a water contact angle of at least one surface of less than 50 ° from the viewpoint of bonding with a very hydrophilic polarizer. The contact angle of water is more preferably less than 40 °, and particularly preferably less than 30 °. The water contact angle is determined from the angle formed by the film surface and water droplets after the film is conditioned at 25 ° C. and a relative humidity of 60% for 2 hours or more, and then a drop of pure water having a diameter of 3 mm is dropped on the surface.
The cellulose acylate film of the present invention preferably has a water contact angle of at least one surface of less than 50 °, and more preferably a cellulose acylate film having a water contact angle of both surfaces of less than 50 °.

(Haze)
The film of the present invention after the saponification treatment preferably has a haze of 1.0% or less from the viewpoint of being used as a polarizing plate as an optical film. The haze is more preferably 0.8% or less, and particularly preferably 0.6% or less.

(Retardation)
The film of the present invention after the saponification treatment has a front retardation value Re (590) at a wavelength of 590 nm and a retardation value Rth (590) in the film thickness direction at a wavelength of 590 nm satisfying the following formulas (I) and (II): Is preferred.
Formula (I): 30 nm ≦ Re (590) ≦ 70 nm
Formula (II): 80 nm ≦ Rth (590) ≦ 250 nm

Re (590) is more preferably 35 nm ≦ Re (590) ≦ 65 nm, and particularly preferably 40 nm ≦ Re (590) ≦ 60 nm.
Rth (590) more preferably satisfies 60 nm ≦ Rth (590) ≦ 250 nm, and particularly preferably satisfies 80 nm ≦ Rth (590) ≦ 150 nm. By setting such Rth (590), a VA retardation film with less color shift can be produced.

  Here, Re (λ) and Rth (λ) represent in-plane retardation and retardation in the thickness direction at the wavelength λ, respectively. In the present specification, the wavelength λ is 590 nm unless otherwise specified. Re (λ) is measured by making light having a wavelength of λ nm incident in the normal direction of the film in KOBRA 21ADH (manufactured by Oji Scientific Instruments). Rth (λ) is Re (λ), with the in-plane slow axis (determined by KOBRA 21ADH) as the tilt axis (rotary axis) (in the absence of the slow axis, any direction in the film plane) Is measured in 6 points from the inclined direction in 10 degree steps from the normal direction to 50 degrees on one side with respect to the normal direction of the film. KOBRA 21ADH calculates based on the retardation value, the assumed average refractive index, and the input film thickness value. The retardation value is measured from any two directions with the slow axis as the tilt axis (rotation axis) (in the absence of the slow axis, the arbitrary direction in the film plane is the rotation axis), and the value Rth can also be calculated from the following formula (a) and formula (b) based on the assumed average refractive index and the input film thickness value. Here, as the assumed value of the average refractive index, values in the polymer handbook (John Wiley & Sons, Inc.) and catalogs of various optical films can be used. Those whose average refractive index is not known can be measured with an Abbe refractometer. The average refractive index values of main optical films are exemplified below: cellulose acylate (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49), Polystyrene (1.59). The KOBRA 21ADH calculates nx, ny, and nz by inputting the assumed value of the average refractive index and the film thickness. Nz = (nx−nz) / (nx−ny) is further calculated from the calculated nx, ny, and nz.

Here, Re (θ) represents a retardation value in a direction inclined by an angle θ from the normal direction. d represents the film thickness.
Rth = ((nx + ny) / 2−nz) × d Formula (b)
At this time, an average refractive index n is required as a parameter, and a value measured by an Abbe refractometer (“Abbe refractometer 2-T” manufactured by Atago Co., Ltd.) was used.

In the protective film for polarizing plate of the present invention, the cellulose-based resin bears 40% or more of what contributes to the optical expression of Re. Here, to contribute to the expression of Re means to cause the expression of Re. That is, as a method for expressing Re, stretching of a film, addition of a Re developing agent, and the like are common. However, in the present invention, Re expression does not depend only on these, and 40% of Re expression occurs. Is caused by cellulosic resin. Preferably, the protective film for polarizing plates of the present invention satisfies the following formula.
(Formula) Re ₂ / d ₂ ≧ Re ₁ / d ₁ × 0.4
(In the above formula, Re ₁ and d ₁ represent Re and film thickness when a protective film for polarizing plate produced with a film thickness of 80 μm is stretched 20% at 180 ° C., respectively, Re ₂ and d ₂ These show the Re value and film thickness when 20% of the protective film for polarizing plate produced with a film thickness of 80 μm without adding an additive that contributes to optical expression is stretched at 180 ° C., respectively. Further, 20 μm ≦ d ₁ ≦ 120 μm and 20 μm ≦ d ₂ ≦ 120 μm.)

The additive that contributes to the optical expression mentioned here corresponds to an Re developing agent, an Rth control agent, a plasticizer, a peeling accelerator, and the like.
That is, the protective film for a polarizing plate of the present invention may contain various additives that contribute to optical expression such as an Re developing agent and an Rth control agent, but the Re value (Re ₁ ) when these are included. And the Re value (Re ₂ ) assuming that these are not included preferably satisfy the above formula.
The ratio contributing to the optical expression of Re is more preferably 40% or more.

<Additives>
In the present invention, known high molecular weight additives and low molecular weight additives can be widely employed as additives for cellulose acylate films. The content of the additive is 1 to 35% by mass, preferably 4 to 30% by mass, and more preferably 10 to 25% by mass with respect to the cellulose resin. If the addition amount is 1% by mass or less, it cannot cope with the temperature and humidity change, and if the addition amount is 30% by mass or more, the film is whitened. In addition, the physical characteristics will be inferior.
Here, the additive in the present invention is a component added for the purpose of improving various functions of the optical film of the present invention, and a component contained in a range of 1% by mass or more with respect to the cellulose resin. Say. That is, impurities and residual solvents are not additives in the present invention.
In the present invention, in particular, the content of the high molecular weight additive is preferably 4 to 30% by mass and more preferably 10 to 25% by mass with respect to the cellulose resin.
In the present invention, two or more kinds of additives can be used as long as the value of ΔSP is within a predetermined range. By using two or more types, each additive has the merit that both optical properties, film elastic modulus, film brittleness, and web handling suitability can be achieved.

(High molecular weight additive)
The high molecular weight additive used in the film of the present invention has a repeating unit in the compound, and preferably has a number average molecular weight of 700 or more and 10,000 or less. The high molecular weight additive is used in the solution casting method to increase the volatilization rate of the solvent or reduce the residual solvent amount. Also in a film formed by the melt film forming method, the high molecular weight additive is a useful material for preventing coloring and film strength deterioration. Furthermore, the addition of the high molecular weight additive to the film of the present invention has a useful effect from the viewpoint of film modification such as improvement of mechanical properties, imparting flexibility, imparting water absorption resistance, and reducing moisture permeability. .

Here, the number average molecular weight of the high molecular weight additive in the present invention is more preferably a number average molecular weight of 700 or more and less than 10,000, still more preferably a number average molecular weight of 800 to 8000, still more preferably a number average molecular weight of 800 to 8000. 5000, particularly preferably a number average molecular weight of 1000 to 5000. By setting it as such a range, it is more excellent in compatibility.
Hereinafter, although the high molecular weight additive used for this invention is demonstrated in detail, giving the specific example, it cannot be overemphasized that the high molecular weight additive used by this invention is not necessarily limited to these.

  The polymer additive is selected from polyester polymers, styrene polymers, acrylic polymers, and copolymers thereof, and aliphatic polyesters, aromatic polyesters, acrylic polymers, and styrene polymers are preferred. Moreover, it is preferable that at least one polymer having negative intrinsic birefringence, such as a styrene polymer and an acrylic polymer, is included.

Polyester polymer The polyester polymer used in the present invention is a mixture of an aliphatic dicarboxylic acid having 2 to 20 carbon atoms and an aromatic dicarboxylic acid having 8 to 20 carbon atoms, an aliphatic diol having 2 to 12 carbon atoms, and a carbon number. It is obtained by a reaction with at least one kind of diol selected from 4-20 alkyl ether diols and C6-C20 aromatic diols, and both ends of the reactants may remain as reactants. Further, the so-called terminal sealing may be carried out by further reacting monocarboxylic acids, monoalcohols or phenols. It is effective in terms of storage stability that the end capping is performed in particular so as not to contain free carboxylic acids. The dicarboxylic acid used in the polyester polymer of the present invention is preferably an aliphatic dicarboxylic acid residue having 4 to 20 carbon atoms or an aromatic dicarboxylic acid residue having 8 to 20 carbon atoms.

Examples of the aliphatic dicarboxylic acid having 2 to 20 carbon atoms preferably used in the present invention include oxalic acid, malonic acid, succinic acid, maleic acid, fumaric acid, glutaric acid, adipic acid, pimelic acid, suberic acid, and azelaic acid. , Sebacic acid, dodecanedicarboxylic acid and 1,4-cyclohexanedicarboxylic acid.
Examples of the aromatic dicarboxylic acid having 8 to 20 carbon atoms include phthalic acid, terephthalic acid, isophthalic acid, 1,5-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 2,8 -Naphthalenedicarboxylic acid and 2,6-naphthalenedicarboxylic acid.

  Among these, preferable aliphatic dicarboxylic acids are malonic acid, succinic acid, maleic acid, fumaric acid, glutaric acid, adipic acid, azelaic acid, and 1,4-cyclohexanedicarboxylic acid, and aromatic dicarboxylic acid is phthalic acid. Acid, terephthalic acid, isophthalic acid, 1,5-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid. Particularly preferably, the aliphatic dicarboxylic acid component is succinic acid, glutaric acid, and adipic acid, and the aromatic dicarboxylic acid is phthalic acid, terephthalic acid, and isophthalic acid.

  In the present invention, at least one of each of the above-mentioned aliphatic dicarboxylic acids and aromatic dicarboxylic acids is used in combination, but the combination is not particularly limited, and there is no problem even if several types of each component are combined.

  Diols or aromatic ring-containing diols used for high molecular weight additives include, for example, aliphatic diols having 2 to 20 carbon atoms, alkyl ether diols having 4 to 20 carbon atoms, and aromatic diols having 6 to 20 carbon atoms. It is chosen from.

  Examples of the aliphatic diol having 2 to 20 carbon atoms include alkyl diols and alicyclic diols, such as ethane diol, 1,2-propanediol, 1,3-propanediol, and 1,2-butane. Diol, 1,3-butanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethyl-1,3-propanediol (neopentyl glycol) ), 2,2-diethyl-1,3-propanediol (3,3-dimethylolpentane), 2-n-butyl-2-ethyl-1,3-propanediol (3,3-dimethylolheptane), 3 -Methyl-1,5-pentanediol, 1,6-hexanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-ethyl 1,3-hexanediol, 2-methyl-1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-octadecanediol, and the like. Used as a mixture of two or more.

  Preferred aliphatic diols include ethanediol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 2-methyl-1,3-propanediol, 1 , 4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, particularly preferred Is ethanediol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6- Hexanediol, 1,4-cyclohexanediol, and 1,4-cyclohexanedimethanol.

  Preferred examples of the alkyl ether diol having 4 to 20 carbon atoms include polytetramethylene ether glycol, polyethylene ether glycol and polypropylene ether glycol, and combinations thereof. The average degree of polymerization is not particularly limited, but is preferably 2 to 20, more preferably 2 to 10, further 2 to 5, and particularly preferably 2 to 4. As examples of these, commercially useful polyether glycols typically include Carbowax resin, Pluronics resin and Niax resin.

  Examples of the aromatic diol having 6 to 20 carbon atoms include, but are not limited to, bisphenol A, 1,2-hydroxybenzene, 1,3-hydroxybenzene, 1,4-hydroxybenzene, and 1,4-benzenedimethanol. Bisphenol A, 1,4-hydroxybenzene and 1,4-benzenedimethanol are preferred.

In the present invention, a high molecular weight additive whose end is sealed with an alkyl group or an aromatic group is particularly preferable. This is because the terminal is protected with a hydrophobic functional group, which is effective against deterioration with time at high temperature and high humidity, and is due to the role of delaying hydrolysis of the ester group.
It is preferable to protect with a monoalcohol residue or a monocarboxylic acid residue so that both ends of the polyester additive of the present invention are not carboxylic acid or OH group.
In this case, the monoalcohol is preferably a substituted or unsubstituted monoalcohol having 1 to 30 carbon atoms, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, pentanol, isopentanol, hexanol, isohexanol, cyclohexyl alcohol. , Octanol, isooctanol, 2-ethylhexyl alcohol, nonyl alcohol, isononyl alcohol, tert-nonyl alcohol, decanol, dodecanol, dodecahexanol, aliphatic alcohol such as dodecaoctanol, allyl alcohol, oleyl alcohol, benzyl alcohol, 3-phenyl Examples thereof include substituted alcohols such as propanol.

  End-capping alcohols that can be preferably used are methanol, ethanol, propanol, isopropanol, butanol, isobutanol, isopentanol, hexanol, isohexanol, cyclohexyl alcohol, isooctanol, 2-ethylhexyl alcohol, isononyl alcohol, oleyl alcohol Benzyl alcohol, in particular methanol, ethanol, propanol, isobutanol, cyclohexyl alcohol, 2-ethylhexyl alcohol, isononyl alcohol, benzyl alcohol.

  Moreover, when sealing with a monocarboxylic acid residue, the monocarboxylic acid used as a monocarboxylic acid residue is preferably a substituted or unsubstituted monocarboxylic acid having 1 to 30 carbon atoms. These may be aliphatic monocarboxylic acids or aromatic ring-containing carboxylic acids. Preferred aliphatic monocarboxylic acids are described, for example, acetic acid, propionic acid, butanoic acid, caprylic acid, caproic acid, decanoic acid, dodecanoic acid, stearic acid, oleic acid, and examples of the aromatic ring-containing monocarboxylic acid include Benzoic acid, p-tert-butylbenzoic acid, p-tert-amylbenzoic acid, orthotoluic acid, metatoluic acid, p-toluic acid, dimethylbenzoic acid, ethylbenzoic acid, normal propylbenzoic acid, aminobenzoic acid, acetoxybenzoic acid, etc. Yes, these can be used alone or in combination of two or more.

The synthesis of the high molecular weight additive of the present invention may be carried out by a conventional method, a hot melt condensation method using a polyesterification reaction or a transesterification reaction between the dicarboxylic acid and a diol and / or a monocarboxylic acid or monoalcohol for end-capping. Alternatively, it can be easily synthesized by any of the interfacial condensation methods of acid chlorides of these acids and glycols. These polyester-based additives are described in detail in Koichi Murai, “Additives, Theory and Application” (Kokaibo Co., Ltd., first edition published on March 1, 1973). In addition, Japanese Patent Laid-Open Nos. 05-155809, 05-155810, Japanese Patent Laid-Open Nos. 05-97073, 2006-259494, 07-330670, 2006-342227, 2007-003679. The materials described in each publication can also be used.
Although the specific example of the polyester-type polymer which can be used by this invention is described below, the polyester-type polymer which can be used by this invention is not limited to these.

  In Tables 1 and 2, PA is phthalic acid, TPA is terephthalic acid, IPA is isophthalic acid, AA is adipic acid, SA is succinic acid, 2,6-NPA is 2,6-naphthalenedicarboxylic acid 2,8-NPA is 2,8-naphthalenedicarboxylic acid, 1,5-NPA is 1,5-naphthalenedicarboxylic acid, 1,4-NPA is 1,4-naphthalenedicarboxylic acid, 1,8 -NPA represents 1,8-naphthalenedicarboxylic acid, respectively.

(Low molecular weight additive)
Examples of the low molecular weight additive include an Rth control agent / regulator, a deterioration preventing agent, an ultraviolet ray preventing agent, a peeling accelerator, another plasticizer, and an infrared absorber. These may be solid or oily. That is, the melting point and boiling point are not particularly limited. For example, mixing of an ultraviolet absorbing material at 20 ° C. or lower and 20 ° C. or higher, and a mixture of deterioration preventing agents are also possible. Furthermore, infrared absorbing dyes are described, for example, in JP-A No. 2001-194522. Moreover, the addition time may be added at any time in the cellulose acylate solution (dope) preparation step, but it may be added by adding a preparation step to the final preparation step of the dope preparation step. Furthermore, the amount of each material added is not particularly limited as long as the function is manifested.

(Rth control agent)
The optical film of the present invention may contain an Rth control agent.
Although it does not specifically limit as a Rth control agent, The details are described in [0066]-[0074] of Unexamined-Japanese-Patent No. 2007-272177.

The compound represented by the general formula (1) or the general formula (2) in JP-A-2007-272177 can be prepared by the following method.
The compound of the general formula (1) in this publication can be obtained by a condensation reaction between a sulfonyl chloride derivative and an amine derivative. The compound of the general formula (2) can be obtained by oxidation reaction of sulfide or Friedel-Crafts reaction of aromatic compound and sulfonic acid chloride. Details are described in JP-A-2007-272177, [0075] to [0085].

(Aliphatic polyhydric alcohol ester)
The film of the present invention contains an aliphatic polyhydric alcohol ester formed from an aliphatic polyhydric alcohol and one or more monocarboxylic acids as a plasticizer, and has high stability such as optical characteristics and dimensions. It is preferable at the point which can obtain a film.
Hereinafter, the aliphatic polyhydric alcohol ester will be described in detail.

  The aliphatic polyhydric alcohol ester according to the present invention is formed from an ester of a dihydric or higher aliphatic polyhydric alcohol and one or more monocarboxylic acids.

  The aliphatic polyhydric alcohol according to the present invention is a dihydric or higher alcohol, but is preferably represented by the following general formula (3).

General formula (3)
R ^91- (OH) m
In the formula, R ⁹¹ represents an n-valent aliphatic organic group, n represents a positive integer of 2 or more, an OH group represents an alcoholic or phenolic hydroxyl group, and m is preferably 2 to 20.

  In the general formula (3), among the n-valent aliphatic organic groups, the divalent group includes an alkylene group (for example, a methylene group, an ethylene group, a trimethylene group, a tetramethylene group, a propylene group, an ethylethylene group, Pentamethylene group, hexamethylene group, etc.), alkenylene group (eg, vinylene group, propenylene group, ethenylene group, etc.), alkynylene group (eg, ethynylene group, 3-pentynylene group, etc.), cycloalkylene group (eg, 1,4 -Cyclohexanediyl group etc.) etc. are mentioned.

  In the general formula (3), among the n-valent aliphatic organic groups, examples of the trivalent group include ethanetriyl group, propanetriyl group, butanetriyl group, pentanetriyl group, hexanetriyl group, heptanetriyl group. Yl group, octanetriyl group, nonanetriyl group, decanetriyl group, undecanetriyl group, dodecanetriyl group, cyclohexanetriyl group, cyclopentanetriyl group, benzenetriyl group, naphthalenetriyl group, 1,2,3- Examples thereof include a propanetriyl group.

  In the general formula (3), among the n-valent aliphatic organic groups, examples of the tetravalent group include a propanediylidene group, a 1,3-propanediyl-2-ylidene group, a butanediylidene group, and a pentanediylidene group. Group, hexanediylidene group, heptanediylidene group, octanediylidene group, nonanediylidene group, decandiylidene group, undecandiylidene group, dodecandiylidene group, cyclohexanediylidene group, cyclopentanediylidene group, benzenetetrayl group, naphthalene A tetrayl group etc. are mentioned.

  The n-valent aliphatic organic group may further have a substituent. Examples of the substituent include an alkyl group (for example, a methyl group, an ethyl group, a butyl group, a pentyl group, 2- Methoxyethyl group, trifluoromethyl group, 2-ethylhexyl group, etc.), aryl group (for example, phenyl group, naphthyl group, etc.), alkoxyl group (for example, methoxy group, ethoxy group, butoxy group, etc.), alkoxycarbonyl group ( For example, methoxycarbonyl group, i-propoxycarbonyl group, etc.), acyloxy group (eg, acetyloxy group, ethylcarbonyloxy group, etc.), carbamoyl group (eg, methylcarbamoyl group, ethylcarbamoyl group, butylcarbamoyl group, phenylcarbamoyl group) ), Sulfamoyl group (for example, sulfamoyl group) Methylsulfamoyl group, dimethylsulfamoyl group, phenylsulfamoyl group, etc.), alkylthio group (eg, methylthio group, ethylthio group, octylthio group, etc.), arylthio group (eg, phenylthio group, p-tolylthio group, etc.) An amino group (for example, amino group, methylamino group, diethylamino group, methoxyethylamino group), acylamino group (for example, acetylamino group, chloroacetylamino group, propionylamino group, benzoylamino group, trifluoroacetylamino group) Etc.), alkylureido groups (eg, methylureido group, ethylureido group, methoxyethylureido group, dimethylureido group, etc.), arylureido groups (eg, phenylureido group, etc.), alkylsulfonamide groups (eg, methanesulfonamido) Group, ethanesulfonamide group, butanesulfonamide group, trifluoromethylsulfonamide group, 2,2,2-trifluoroethylsulfonamide group, etc.), arylsulfonamide group (for example, phenylsulfonamide group, tolylsulfonamide group) Etc.), alkylaminosulfonylamino group (eg, methylaminosulfonylamino group, ethylaminosulfonylamino group, etc.), arylaminosulfonylamino group (eg, phenylaminosulfonylamino group, etc.), hydroxyl group, cyano group, nitro group, Heterocyclic groups (for example, pyridyl group, pyrimidyl group, pyrazyl group, pyrrolyl group, indolyl group, pyrazolyl group, imidazolyl group, furyl group, oxazolyl group, thiazolyl group, quinolyl group, thienyl group, etc.) can be mentioned.

  Examples of preferred aliphatic polyhydric alcohols include, for example, adonitol, arabitol, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propanediol, dipropylene glycol, tripropylene Glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, dibutylene glycol, 1,2,4-butanetriol, 1,5-pentanediol, 1,6-hexanediol, Examples include hexanetriol, galactitol, mannitol, 3-methylpentane-1,3,5-triol, pinacol, sorbitol, trimethylolpropane, trimethylolethane, and xylitol.

  Among these, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, sorbitol, trimethylolpropane, and xylitol are particularly preferably used.

  There is no restriction | limiting in particular as monocarboxylic acid used for aliphatic polyhydric-alcohol ester formation based on this invention, Well-known aliphatic monocarboxylic acid, alicyclic monocarboxylic acid, aromatic monocarboxylic acid, etc. can be used. However, it is preferable to use an alicyclic monocarboxylic acid or an aromatic monocarboxylic acid from the viewpoint of improving the moisture permeability and retention of the cellulose ester film.

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

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

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

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

  Examples of preferred aromatic monocarboxylic acids include those in which an alkyl group is introduced into the benzene ring of benzoic acid such as benzoic acid and toluic acid, and two or more benzene rings such as biphenylcarboxylic acid, naphthalenecarboxylic acid, and tetralincarboxylic acid. The aromatic monocarboxylic acid which has, or those derivatives can be mentioned. Benzoic acid is particularly preferable. In addition, the aromatic ring of the aromatic monocarboxylic acid may have a substituent.

Molecular weight of aliphatic polyhydric alcohol ester The molecular weight of the polyhydric alcohol ester according to the present invention is not particularly limited, but is preferably 300 to 1500, and more preferably 350 to 750. The larger one is preferable in terms of retention, and the smaller one is preferable in terms of moisture permeability and compatibility with the cellulose ester.

  Here, the molecular weight of the aliphatic polyhydric alcohol ester can be measured using a commercially available GPC (gel permeation chromatography) apparatus.

  The carboxylic acid in the aliphatic polyhydric alcohol ester according to the present invention may be one kind or a mixture of two or more kinds. Moreover, all the OH groups in the aliphatic polyhydric alcohol may be esterified, or a part of the OH groups may be left as they are. Preferably, it has 3 or more aromatic rings or cycloalkyl rings in the molecule.

  The aromatic ring used in the present invention includes an aromatic carbocyclic ring (for example, a benzene ring, a naphthalene ring, a biphenyl ring, a p-terphenyl ring, a diphenylmethane ring, a triphenylmethane ring, a bibenzyl ring, a stilbene ring, an indene ring, Tetralin ring, anthracene ring, phenanthrene ring, etc.) and aromatic heterocycles such as furan ring, pyrrole ring, pyrazole ring, imidazole ring, oxazole ring, thiazole ring, 1,2,3-oxadiazole ring, 1,2 , 3-triazole ring, 1,2,4-triazole ring, 1,3,4-thiadiazole ring, pyridine ring, pyridazine ring, pyrimidine ring, pyrazine ring, s-triazine ring, benzofuran ring, indole ring, benzothiophene ring , Benzimidazole ring, benzothiazole ring, purine ring, quinoline ring and iso Norin ring and the like.

  Examples of the cycloalkyl ring used in the present invention include a cyclopentane ring, a cyclohexane ring, and a cyclooctane ring.

  Hereinafter, although the specific example of the aliphatic polyhydric alcohol ester which concerns on this invention is shown, this invention is not limited to these.

  The amount of the aliphatic polyhydric alcohol ester according to the present invention (may be the content) is preferably in the range of 3% by mass to 30% by mass, more preferably in the range of 5% by mass to 25% by mass with respect to the film. Especially preferably, it is the range of 5 mass%-20 mass%.

(Re expression agent)
In the present invention, a retardation developer may be included. The retardation developing agent can be included, for example, in a proportion of 0.5 to 10% by weight, and further can be included in a proportion of 2 to 6% by weight. By adopting a retardation developer, high Re developability can be obtained at a low draw ratio. The type of retardation enhancer is not particularly defined, but examples thereof include those composed of rod-like or discotic compounds. As the rod-like or discotic compound, a compound having at least two aromatic rings can be preferably used as a retardation developer. The addition amount of the retardation developer composed of the rod-like compound is preferably 0.5 to 10 parts by mass, more preferably 2 to 6 parts by mass with respect to 100 parts by mass of the polymer component containing cellulose acylate. .
The discotic retardation enhancer is preferably used in the range of 0.5 to 10 parts by mass and in the range of 1 to 8 parts by mass with respect to 100 parts by mass of the polymer component containing the cellulose acylate. It is more preferable to use in the range of 2 to 6 parts by mass.
Two or more retardation developing agents may be used in combination.
The retardation developer preferably has a maximum absorption in the wavelength region of 250 to 400 nm, and preferably has substantially no absorption in the visible region.

The discotic compound will be described. As the discotic compound, a compound having at least two aromatic rings can be used.
In the present specification, the “aromatic ring” includes an aromatic hetero ring in addition to an aromatic hydrocarbon ring.
The aromatic hydrocarbon ring is particularly preferably a 6-membered ring (that is, a benzene ring).
The aromatic heterocycle is generally an unsaturated heterocycle. The aromatic heterocycle is preferably a 5-membered ring, 6-membered ring or 7-membered ring, more preferably a 5-membered ring or 6-membered ring. Aromatic heterocycles generally have the most double bonds. As the hetero atom, a nitrogen atom, an oxygen atom and a sulfur atom are preferable, and a nitrogen atom is particularly preferable. Examples of aromatic heterocycles include furan ring, thiophene ring, pyrrole ring, oxazole ring, isoxazole ring, thiazole ring, isothiazole ring, imidazole ring, pyrazole ring, furazane ring, triazole ring, pyran ring, pyridine ring , Pyridazine ring, pyrimidine ring, pyrazine ring and 1,3,5-triazine ring.
As the aromatic ring, a benzene ring, a condensed benzene ring, and biphenyls are preferable. In particular, a 1,3,5-triazine ring is preferably used. Specifically, for example, compounds disclosed in JP-A No. 2001-166144 are preferably used.

The number of carbon atoms of the aromatic ring in the retardation enhancer is preferably 2-20, more preferably 2-12, still more preferably 2-8, and 2-6. Most preferred.
The bonding relationship between two aromatic rings can be classified into (a) when a condensed ring is formed, (b) when directly linked by a single bond, and (c) when linked via a linking group (for aromatic rings). , Spiro bonds cannot be formed). The connection relationship may be any of (a) to (c).

  Examples of the condensed ring (a condensed ring of two or more aromatic rings) include an indene ring, a naphthalene ring, an azulene ring, a fluorene ring, a phenanthrene ring, an anthracene ring, an acenaphthylene ring, a biphenylene ring, a naphthacene ring, Pyrene ring, indole ring, isoindole ring, benzofuran ring, benzothiophene ring, indolizine ring, benzoxazole ring, benzothiazole ring, benzimidazole ring, benzotriazole ring, purine ring, indazole ring, chromene ring, quinoline ring, isoquinoline Ring, quinolidine ring, quinazoline ring, cinnoline ring, quinoxaline ring, phthalazine ring, pteridine ring, carbazole ring, acridine ring, phenanthridine ring, xanthene ring, phenazine ring, phenothiazine ring, phenoxathiin ring, phenoxazine ring and thiant It includes emissions ring. Naphthalene ring, azulene ring, indole ring, benzoxazole ring, benzothiazole ring, benzimidazole ring, benzotriazole ring and quinoline ring are preferred.

  The single bond (b) is preferably a bond between carbon atoms of two aromatic rings. Two aromatic rings may be bonded with two or more single bonds to form an aliphatic ring or a non-aromatic heterocyclic ring between the two aromatic rings.

The linking group in (c) is also preferably bonded to carbon atoms of two aromatic rings. The linking group is preferably an alkylene group, an alkenylene group, an alkynylene group, —CO—, —O—, —NH—, —S—, or a combination thereof. Examples of linking groups composed of combinations are shown below. In addition, the relationship between the left and right in the following examples of the linking group may be reversed.
c1: -CO-O-
c2: —CO—NH—
c3: -alkylene-O-
c4: —NH—CO—NH—
c5: —NH—CO—O—
c6: —O—CO—O—
c7: -O-alkylene-O-
c8: -CO-alkenylene-
c9: -CO-alkenylene-NH-
c10: -CO-alkenylene-O-
c11: -alkylene-CO-O-alkylene-O-CO-alkylene-
c12: -O-alkylene-CO-O-alkylene-O-CO-alkylene-O-
c13: -O-CO-alkylene-CO-O-
c14: -NH-CO-alkenylene-
c15: -O-CO-alkenylene-

The aromatic ring and the linking group may have a substituent.
Examples of substituents include halogen atoms (F, Cl, Br, I), hydroxyl groups, carboxyl groups, cyano groups, amino groups, nitro groups, sulfo groups, carbamoyl groups, sulfamoyl groups, ureido groups, alkyl groups, alkenyls. Group, alkynyl group, aliphatic acyl group, aliphatic acyloxy group, alkoxy group, alkoxycarbonyl group, alkoxycarbonylamino group, alkylthio group, alkylsulfonyl group, aliphatic amide group, aliphatic sulfonamido group, aliphatic substituted amino group An aliphatic substituted carbamoyl group, an aliphatic substituted sulfamoyl group, an aliphatic substituted ureido group, and a non-aromatic heterocyclic group.

It is preferable that the alkyl group has 1 to 8 carbon atoms. A chain alkyl group is preferable to a cyclic alkyl group, and a linear alkyl group is particularly preferable. The alkyl group may further have a substituent (for example, a hydroxy group, a carboxy group, an alkoxy group, an alkyl-substituted amino group). Examples of alkyl groups (including substituted alkyl groups) include methyl, ethyl, n-butyl, n-hexyl, 2-hydroxyethyl, 4-carboxybutyl, 2-methoxyethyl, and 2- Each group of a diethylaminoethyl group is included.
The alkenyl group preferably has 2 to 8 carbon atoms. A chain alkenyl group is preferable to a cyclic alkenyl group, and a linear alkenyl group is particularly preferable. The alkenyl group may further have a substituent. Examples of the alkenyl group include a vinyl group, an allyl group, and a 1-hexenyl group.
The alkynyl group preferably has 2 to 8 carbon atoms. A chain alkynyl group is preferable to a cyclic alkynyl group, and a linear alkynyl group is particularly preferable. The alkynyl group may further have a substituent. Examples of the alkynyl group include ethynyl group, 1-butynyl group and 1-hexynyl group.

The number of carbon atoms in the aliphatic acyl group is preferably 1-10. Examples of the aliphatic acyl group include an acetyl group, a propanoyl group, and a butanoyl group.
The number of carbon atoms in the aliphatic acyloxy group is preferably 1-10. Examples of the aliphatic acyloxy group include an acetoxy group.
The number of carbon atoms of the alkoxy group is preferably 1-8. The alkoxy group may further have a substituent (for example, an alkoxy group). Examples of the alkoxy group (including a substituted alkoxy group) include a methoxy group, an ethoxy group, a butoxy group, and a methoxyethoxy group.
The number of carbon atoms of the alkoxycarbonyl group is preferably 2-10. Examples of the alkoxycarbonyl group include a methoxycarbonyl group and an ethoxycarbonyl group.
The number of carbon atoms of the alkoxycarbonylamino group is preferably 2-10. Examples of the alkoxycarbonylamino group include a methoxycarbonylamino group and an ethoxycarbonylamino group.

The alkylthio group preferably has 1 to 12 carbon atoms. Examples of the alkylthio group include a methylthio group, an ethylthio group, and an octylthio group.
The alkylsulfonyl group preferably has 1 to 8 carbon atoms. Examples of the alkylsulfonyl group include a methanesulfonyl group and an ethanesulfonyl group.
The number of carbon atoms in the aliphatic amide group is preferably 1-10. Examples of the aliphatic amide group include acetamide.
The number of carbon atoms of the aliphatic sulfonamide group is preferably 1-8. Examples of the aliphatic sulfonamido group include a methanesulfonamido group, a butanesulfonamido group, and an n-octanesulfonamido group.
The number of carbon atoms of the aliphatic substituted amino group is preferably 1-10. Examples of the aliphatic substituted amino group include a dimethylamino group, a diethylamino group, and a 2-carboxyethylamino group.
The number of carbon atoms in the aliphatic substituted carbamoyl group is preferably 2-10. Examples of the aliphatic substituted carbamoyl group include a methylcarbamoyl group and a diethylcarbamoyl group.
The number of carbon atoms in the aliphatic substituted sulfamoyl group is preferably 1-8. Examples of the aliphatic substituted sulfamoyl group include a methylsulfamoyl group and a diethylsulfamoyl group.
The number of carbon atoms in the aliphatic substituted ureido group is preferably 2-10. Examples of the aliphatic substituted ureido group include a methylureido group.
Examples of the non-aromatic heterocyclic group include a piperidino group and a morpholino group.
The molecular weight of the retardation developer is preferably 300 to 800.

  As the discotic compound, a triazine compound represented by the following general formula (I) is preferably used.

In the above general formula (I):
R ⁵¹ each independently represents an aromatic ring or a heterocyclic ring having a substituent in at least one of the ortho, meta and para positions.
X ¹¹ each independently represents a single bond or —NR ⁵² —. Here, each R ⁵² independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, an alkenyl group, an aryl group, or a heterocyclic group.

The aromatic ring represented by R ⁵¹ is preferably phenyl or naphthyl, and particularly preferably phenyl. The aromatic ring represented by R ⁵¹ may have at least one substituent at any substitution position. Examples of the substituent include halogen atom, hydroxyl group, cyano group, nitro group, carboxyl group, alkyl group, alkenyl group, aryl group, alkoxy group, alkenyloxy group, aryloxy group, acyloxy group, alkoxycarbonyl group, Alkenyloxycarbonyl group, aryloxycarbonyl group, sulfamoyl group, alkyl-substituted sulfamoyl group, alkenyl-substituted sulfamoyl group, aryl-substituted sulfamoyl group, sulfonamide group, carbamoyl, alkyl-substituted carbamoyl group, alkenyl-substituted carbamoyl group, aryl-substituted carbamoyl group, amide Groups, alkylthio groups, alkenylthio groups, arylthio groups and acyl groups.

The heterocyclic group represented by R ⁵¹ preferably has aromaticity. The heterocycle having aromaticity is generally an unsaturated heterocycle, preferably a heterocycle having the largest number of double bonds. The heterocyclic ring is preferably a 5-membered ring, 6-membered ring or 7-membered ring, more preferably a 5-membered ring or 6-membered ring, and most preferably a 6-membered ring. The hetero atom of the heterocyclic ring is preferably a nitrogen atom, a sulfur atom or an oxygen atom, and particularly preferably a nitrogen atom. As the heterocyclic ring having aromaticity, a pyridine ring (2-pyridyl or 4-pyridyl as the heterocyclic group) is particularly preferable. The heterocyclic group may have a substituent. Examples of the substituent of the heterocyclic group are the same as the examples of the substituent of the aryl moiety.
When X ¹¹ is a single bond, the heterocyclic group is preferably a heterocyclic group having a free valence on the nitrogen atom. The heterocyclic group having a free valence on the nitrogen atom is preferably a 5-membered ring, 6-membered ring or 7-membered ring, more preferably a 5-membered ring or 6-membered ring, and a 5-membered ring. Is most preferred. The heterocyclic group may have a plurality of nitrogen atoms. Further, the heterocyclic group may have a hetero atom other than the nitrogen atom (for example, O, S). Examples of heterocyclic groups having free valences on nitrogen atoms are shown below.

The alkyl group represented by R ⁵² may be a cyclic alkyl group or a chain alkyl group, but a chain alkyl group is preferable, and a linear alkyl group is more preferable than a branched chain alkyl group. preferable. The number of carbon atoms of the alkyl group is preferably 1-30, more preferably 1-20, still more preferably 1-10, still more preferably 1-8, and 1-6. Most preferred. The alkyl group may have a substituent. Examples of the substituent include a halogen atom, an alkoxy group (for example, methoxy group, ethoxy group) and an acyloxy group (for example, acryloyloxy group, methacryloyloxy group).

The alkenyl group represented by R ⁵² may be a cyclic alkenyl group or a chain alkenyl group, but is preferably a chain alkenyl group, and is more preferably a linear alkenyl group than a branched chain alkenyl group. More preferably it represents a group. The number of carbon atoms in the alkenyl group is preferably 2 to 30, more preferably 2 to 20, still more preferably 2 to 10, still more preferably 2 to 8, 6 is most preferred. The alkenyl group may have a substituent. Examples of the substituent are the same as those of the alkyl group described above.
The aromatic ring group and heterocyclic group represented by R ⁵² are the same as the aromatic ring and heterocyclic ring represented by R ⁵¹ , and the preferred ranges are also the same. The aromatic ring group and the heterocyclic group may further have a substituent, and examples of the substituent are the same as those of the aromatic ring and heterocyclic ring of R ⁵¹ .

  As the discotic compound, a triphenylene compound represented by the following general formula (II) can also be preferably used.

In the general formula (II), R ⁵³ , R ⁵⁴ , R ⁵⁵ , R ⁵⁶ , R ⁵⁷ and R ⁵⁸ each independently represent a hydrogen atom or a substituent.
As the substituents represented by R ⁵³ , R ⁵⁴ , R ⁵⁵ , R ⁵⁶ , R ⁵⁷ and R ⁵⁸ , an alkyl group (preferably having 1 to 40 carbon atoms, more preferably 1 to 30 carbon atoms, particularly preferably carbon number). 1-20 alkyl groups, such as methyl, ethyl, isopropyl, tert-butyl, n-octyl, n-decyl, n-hexadecyl, cyclopropyl, cyclopentyl, cyclohexyl, etc. ), An alkenyl group (preferably an alkenyl group having 2 to 40 carbon atoms, more preferably 2 to 30 carbon atoms, particularly preferably 2 to 20 carbon atoms, such as a vinyl group, an allyl group, 2- Butenyl group, 3-pentenyl group and the like), alkynyl group (preferably having 2 to 40 carbon atoms, more preferably 2 to 30 carbon atoms, particularly preferably 2 to 2 carbon atoms). 20 alkynyl groups such as propargyl group and 3-pentynyl group) and aryl groups (preferably having 6 to 30 carbon atoms, more preferably 6 to 20 carbon atoms, and particularly preferably 6 to 12 carbon atoms). For example, a phenyl group, a p-methylphenyl group, a naphthyl group, and the like, a substituted or unsubstituted amino group (preferably having 0 to 40 carbon atoms, more preferably 0 to 30 carbon atoms, Particularly preferred is an amino group having 0 to 20 carbon atoms, and examples thereof include an unsubstituted amino group, a methylamino group, a dimethylamino group, a diethylamino group, and an anilino group).

An alkoxy group (preferably an alkoxy group having 1 to 40 carbon atoms, more preferably 1 to 30 carbon atoms, particularly preferably 1 to 20 carbon atoms, and examples thereof include a methoxy group, an ethoxy group, and a butoxy group). Aryloxy group (preferably an aryloxy group having 6 to 40 carbon atoms, more preferably 6 to 30 carbon atoms, particularly preferably 6 to 20 carbon atoms, and examples thereof include a phenyloxy group and a 2-naphthyloxy group. An acyl group (preferably an acyl group having 1 to 40 carbon atoms, more preferably 1 to 30 carbon atoms, and particularly preferably 1 to 20 carbon atoms, such as an acetyl group, a benzoyl group, a formyl group, and a pivaloyl group. Etc.), an alkoxycarbonyl group (preferably having 2 to 40 carbon atoms, more preferably 2 to 30 carbon atoms, and particularly preferably carbon number) To 20 alkoxy groups such as methoxycarbonyl group and ethoxycarbonyl group), aryloxycarbonyl groups (preferably having 7 to 40 carbon atoms, more preferably having 7 to 30 carbon atoms, and particularly preferably carbon atoms). An aryloxycarbonyl group having 7 to 20 carbon atoms, such as a phenyloxycarbonyl group, and an acyloxy group (preferably having 2 to 40 carbon atoms, more preferably 2 to 30 carbon atoms, and particularly preferably 2 carbon atoms). ˜20 acyloxy groups such as an acetoxy group and a benzoyloxy group)

An acylamino group (preferably an acylamino group having 2 to 40 carbon atoms, more preferably 2 to 30 carbon atoms, particularly preferably 2 to 20 carbon atoms, such as an acetylamino group and a benzoylamino group), alkoxycarbonyl An amino group (preferably an alkoxycarbonylamino group having 2 to 40 carbon atoms, more preferably 2 to 30 carbon atoms, particularly preferably 2 to 20 carbon atoms, such as a methoxycarbonylamino group), aryloxy Carbonylamino group (preferably an aryloxycarbonylamino group having 7 to 40 carbon atoms, more preferably 7 to 30 carbon atoms, particularly preferably 7 to 20 carbon atoms, such as a phenyloxycarbonylamino group) Sulfonylamino group (preferably having 1 to 40 carbon atoms, more preferred Or a sulfonylamino group having 1 to 30 carbon atoms, particularly preferably 1 to 20 carbon atoms, such as a methanesulfonylamino group and a benzenesulfonylamino group, and a sulfamoyl group (preferably having a carbon number of 0 to 40). More preferably, it is a sulfamoyl group having 0 to 30 carbon atoms, particularly preferably 0 to 20 carbon atoms, and examples thereof include a sulfamoyl group, a methylsulfamoyl group, a dimethylsulfamoyl group, and a phenylsulfamoyl group. ), A carbamoyl group (preferably a carbamoyl group having 1 to 40 carbon atoms, more preferably 1 to 30 carbon atoms, particularly preferably 1 to 20 carbon atoms, for example, an unsubstituted carbamoyl group, a methylcarbamoyl group, diethylcarbamoyl group Group, phenylcarbamoyl group, etc.),

Alkylthio group (preferably having 1 to 40 carbon atoms, more preferably 1 to 30 carbon atoms, particularly preferably 1 to 20 carbon atoms, for example, methylthio group, ethylthio group, propylthio group, butylthio group, pentylthio group, hexylthio group , Heptylthio group, octylthio group and the like), arylthio group (preferably having 6 to 40 carbon atoms, more preferably 6 to 30 carbon atoms, particularly preferably 1 to 20 carbon atoms, for example, phenylthio group). ), A sulfonyl group (preferably a sulfonyl group having 1 to 40 carbon atoms, more preferably 1 to 30 carbon atoms, particularly preferably 1 to 20 carbon atoms, and examples thereof include a mesyl group and a tosyl group), sulfinyl Group (preferably having 1 to 40 carbon atoms, more preferably 1 to 30 carbon atoms, particularly preferably 1 to 2 carbon atoms) Sulfinyl group, for example, methanesulfinyl group, benzenesulfinyl group, etc.), ureido group (preferably having 1 to 40 carbon atoms, more preferably 1 to 30 carbon atoms, particularly preferably 1 to 20 carbon atoms). A ureido group, for example, an unsubstituted ureido group, a methylureido group, a phenylureido group, and the like, a phosphoric acid amide group (preferably having 1 to 40 carbon atoms, more preferably 1 to 30 carbon atoms, and particularly preferably Is a phosphoric acid amide group having 1 to 20 carbon atoms, and examples thereof include a diethylphosphoric acid amide group and a phenylphosphoric acid amide group, a hydroxy group, a mercapto group, a halogen atom (for example, a fluorine atom, a chlorine atom, bromine). Atom, iodine atom), cyano group, sulfo group, carboxyl group, nitro group, hydroxamic acid group, sulfino group A hydrazino group, an imino group, a heterocyclic group (preferably a heterocyclic group having 1 to 30 carbon atoms, more preferably 1 to 12 carbon atoms, for example, a heterocyclic group having a heteroatom such as a nitrogen atom, oxygen atom, sulfur atom, etc. And examples thereof include imidazolyl group, pyridyl group, quinolyl group, furyl group, piperidyl group, morpholino group, benzoxazolyl group, benzimidazolyl group, benzthiazolyl group, and 1,3,5-triazyl group). Silyl group (preferably a silyl group having 3 to 40 carbon atoms, more preferably 3 to 30 carbon atoms, particularly preferably 3 to 24 carbon atoms, and examples thereof include a trimethylsilyl group and a triphenylsilyl group) Is included. These substituents may be further substituted with these substituents. Moreover, when it has two or more substituents, they may be the same or different. If possible, they may be bonded to each other to form a ring.

The substituent represented by each of R ⁵³ , R ⁵⁴ , R ⁵⁵ , R ⁵⁶ , R ⁵⁷ and R ⁵⁸ is preferably an alkyl group, an aryl group, a substituted or unsubstituted amino group, an alkoxy group, an alkylthio group or a halogen atom. is there.
Details are described on page 49 of the published technical bulletin 2001-1745.

  The compound represented by general formula (I) is, for example, the method described in JP-A No. 2003-344655, and the compound represented by general formula (II) is, for example, the method described in JP-A-2005-134484. Can be synthesized by a known method.

  In the present invention, rod-like compounds having a linear molecular structure can be preferably used in addition to the above-mentioned discotic compounds. The linear molecular structure means that the molecular structure of the rod-like compound is linear in the most thermodynamically stable structure. The most thermodynamically stable structure can be obtained by crystal structure analysis or molecular orbital calculation. For example, molecular orbital calculation can be performed using molecular orbital calculation software (for example, WinMOPAC2000, manufactured by Fujitsu Limited) to obtain a molecular structure that minimizes the heat of formation of a compound. The molecular structure being linear means that in the thermodynamically most stable structure obtained by calculation as described above, the angle of the main chain constituting the molecular structure is 140 degrees or more.

  As the rod-shaped compound having at least two aromatic rings, a compound represented by the following general formula (III) is preferable.

Formula (III): Ar ¹ -L ¹ -Ar ²

In the general formula (III), Ar ¹ and Ar ² are each independently an aromatic group.
In the present specification, the aromatic group includes an aryl group (aromatic hydrocarbon group), a substituted aryl group, an aromatic heterocyclic group, and a substituted aromatic heterocyclic group.
An aryl group and a substituted aryl group are more preferable than an aromatic heterocyclic group and a substituted aromatic heterocyclic group. The heterocycle of the aromatic heterocyclic group is generally unsaturated. The aromatic heterocycle is preferably a 5-membered ring, 6-membered ring or 7-membered ring, more preferably a 5-membered ring or 6-membered ring. Aromatic heterocycles generally have the most double bonds. As a hetero atom, a nitrogen atom, an oxygen atom or a sulfur atom is preferable, and a nitrogen atom or a sulfur atom is more preferable.
As the aromatic ring of the aromatic group, a benzene ring, a furan ring, a thiophene ring, a pyrrole ring, an oxazole ring, a thiazole ring, an imidazole ring, a triazole ring, a pyridine ring, a pyrimidine ring and a pyrazine ring are preferable, and a benzene ring is particularly preferable. .

  Examples of the substituent of the substituted aryl group and the substituted aromatic heterocyclic group include a halogen atom (F, Cl, Br, I), a hydroxyl group, a carboxyl group, a cyano group, an amino group, an alkylamino group (for example, methyl Amino group, ethylamino group, butylamino group, dimethylamino group), nitro group, sulfo group, carbamoyl group, alkylcarbamoyl group (for example, N-methylcarbamoyl group, N-ethylcarbamoyl group, N, N-) Dimethylcarbamoyl group), sulfamoyl group, alkylsulfamoyl group (eg, N-methylsulfamoyl group, N-ethylsulfamoyl group, N, N-dimethylsulfamoyl group), ureido Group, alkylureido group (for example, N-methylureido group, N, N-dimethylureido group, N, N, N′-trimethyl group) Each group of tilureido group), alkyl group (for example, methyl group, ethyl group, propyl group, butyl group, pentyl group, heptyl group, octyl group, isopropyl group, s-butyl group, tert-amyl group, cyclohexyl group, cyclopentyl) Group), alkenyl group (for example, vinyl group, allyl group, hexenyl group), alkynyl group (for example, ethynyl group, butynyl group), acyl group (for example, formyl group, acetyl group, butyryl group, Hexanoyl group, lauryl group), acyloxy group (for example, acetoxy group, butyryloxy group, hexanoyloxy group, lauryloxy group), alkoxy group (for example, methoxy group, ethoxy group, propoxy group, butoxy group) Pentyloxy group, heptyloxy group, octyloxy group), arylo Si group (for example, phenoxy group), alkoxycarbonyl group (for example, methoxycarbonyl group, ethoxycarbonyl group, propoxycarbonyl group, butoxycarbonyl group, pentyloxycarbonyl group, heptyloxycarbonyl group), aryloxycarbonyl group ( For example, phenoxycarbonyl group), alkoxycarbonylamino group (for example, butoxycarbonylamino group, hexyloxycarbonylamino group), alkylthio group (for example, methylthio group, ethylthio group, propylthio group, butylthio group, pentylthio group, heptylthio group, octylthio group) Each group), arylthio group (for example, phenylthio group), alkylsulfonyl group (for example, methylsulfonyl group, ethylsulfonyl group, propylsulfonyl group, butylsulfo group) Group, pentylsulfonyl group, heptylsulfonyl group, octylsulfonyl group), amide group (for example, acetamido group, butyramide group, hexylamide group, laurylamide group) and non-aromatic heterocyclic group ( For example, a morpholyl group and a pyrazinyl group) are included.

Among these, preferred substituents include halogen atoms, cyano groups, carboxyl groups, hydroxyl groups, amino groups, alkylamino groups, acyl groups, acyloxy groups, amide groups, alkoxycarbonyl groups, alkoxy groups, alkylthio groups, and alkyl groups. Can be mentioned.
The alkyl part and the alkyl group of the alkylamino group, alkoxycarbonyl group, alkoxy group and alkylthio group may further have a substituent. Examples of the alkyl moiety and the substituent of the alkyl group include halogen atom, hydroxyl group, carboxyl group, cyano group, amino group, alkylamino group, nitro group, sulfo group, carbamoyl group, alkylcarbamoyl group, sulfamoyl group, alkylsulfur group. Famoyl group, ureido group, alkylureido group, alkenyl group, alkynyl group, acyl group, acyloxy group, alkoxy group, aryloxy group, alkoxycarbonyl group, aryloxycarbonyl group, alkoxycarbonylamino group, alkylthio group, arylthio group, An alkylsulfonyl group, an amide group and a non-aromatic heterocyclic group are included. As the substituent for the alkyl moiety and the alkyl group, a halogen atom, a hydroxyl group, an amino group, an alkylamino group, an acyl group, an acyloxy group, an acylamino group, an alkoxycarbonyl group, and an alkoxy group are preferable.

In the general formula (III), L ¹ is a divalent linking group selected from an alkylene group, an alkenylene group, an alkynylene group, —O—, —CO—, and a combination thereof.
The alkylene group may have a cyclic structure. As the cyclic alkylene group, cyclohexylene is preferable, and 1,4-cyclohexylene is particularly preferable. As the chain alkylene group, a linear alkylene group is more preferable than a branched alkylene group.
The number of carbon atoms of the alkylene group is preferably 1-20, more preferably 1-15, still more preferably 1-10, still more preferably 1-8, and most preferably 1-6. It is.

The alkenylene group and the alkynylene group preferably have a chain structure rather than a cyclic structure, and more preferably have a linear structure rather than a branched chain structure.
The alkenylene group and the alkynylene group preferably have 2 to 10 carbon atoms, more preferably 2 to 8, more preferably 2 to 6, still more preferably 2 to 4, and most preferably 2. (Vinylene group or ethynylene group).
The arylene group preferably has 6 to 20 carbon atoms, more preferably 6 to 16, and still more preferably 6 to 12.

In the molecular structure of the general formula (III), the angle formed by Ar ¹ and Ar ² across L ¹ is preferably 140 degrees or more.

As the rod-like compound, a compound represented by the following formula (IV) is more preferable.
Formula ^{(IV): Ar 1 -L 2} -X-L 3 -Ar 2

In the general formula (IV), Ar ¹ and Ar ² are each independently an aromatic group. The definition and examples of the aromatic group are the same as those of Ar ¹ and Ar ^{2 in} the general formula (III).

In the general formula (IV), L ² and L ³ are each independently a divalent linking group selected from an alkylene group, —O—, —CO— and a group consisting of a combination thereof.
The alkylene group preferably has a chain structure rather than a cyclic structure, and more preferably has a linear structure rather than a branched chain structure.
The alkylene group preferably has 1 to 10 carbon atoms, more preferably 1 to 8, more preferably 1 to 6, still more preferably 1 to 4, and 1 or 2 (methylene group). Or ethylene group).
L ² and L ³ are particularly preferably —O—CO— or —CO—O—.

  In the general formula (IV), X is a 1,4-cyclohexylene group, a vinylene group or an ethynylene group.

  Specific examples of the compound represented by the general formula (III) or (IV) include compounds described in [Chemical Formula 1] to [Chemical Formula 11] of JP-A No. 2004-109657.

Two or more rod-shaped compounds having a maximum absorption wavelength (λmax) longer than 250 nm in the ultraviolet absorption spectrum of the solution may be used in combination.
The rod-like compound can be synthesized with reference to methods described in literature. References include Mol. Cryst. Liq. Cryst., 53, 229 (1979), 89, 93 (1982), 145, 111 (1987), 170, 43 Page (1989), J. Am. Chem. Soc., 113, 1349 (1991), 118, 5346 (1996), 92, 1582 (1970), J. Org Chem., 40, 420 (1975), Tetrahedron, 48, 16, 3437 (1992).

Moreover, you may use the rod-shaped aromatic compound of pages 11-14 of Unexamined-Japanese-Patent No. 2004-50516 as said Re expression agent.
Further, as the Re enhancer, one kind of compound can be used alone, or two or more kinds of compounds can be mixed and used. It is preferable to use two or more compounds different from each other as the Re enhancer because the retardation adjustment range is widened and can be easily adjusted to a desired range.
The addition amount of the Re enhancer is preferably 0.1 to 20% by mass, and more preferably 0.5 to 10% by mass with respect to 100 parts by mass of cellulose acylate. When the cellulose acylate film is produced by a solvent cast method, the Re enhancer may be added to the dope. The addition may be performed at any timing. For example, the Re developing agent may be dissolved in an organic solvent such as alcohol, methylene chloride, dioxolane, etc., and then added to the cellulose acylate solution (dope) or directly. You may add during dope composition.

  In particular, the ratio of the discotic compound is preferably 10% to 90%, more preferably 20% to 80%, based on the total mass of the discotic compound and the rod-shaped compound.

(Peeling accelerator)
It is preferable to add a peeling accelerator to the film of the present invention. The peeling accelerator can be included at a ratio of 0.001 to 1% by weight, for example. As the peeling accelerator, the compounds described in JP-A 2006-45497, paragraphs 0048 to 0069 can be preferably used.

(Matting agent)
It is preferable to add fine particles as a matting agent to the film of the present invention. The fine particles used in the present invention include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, silica Mention may be made of magnesium and calcium phosphates. Fine particles containing silicon are preferable in terms of low turbidity, and silicon dioxide is particularly preferable. The silicon dioxide fine particles preferably have a primary average particle size of 20 nm or less and an apparent specific gravity of 70 g / liter or more. Those having an average primary particle size as small as 5 to 16 nm are more preferred because they can reduce the haze of the film. The apparent specific gravity is preferably 90 to 200 g / liter or more, and more preferably 100 to 200 g / liter or more. A larger apparent specific gravity is preferable because a high-concentration dispersion can be produced, and haze and aggregates are improved.

  These fine particles usually form secondary particles having an average particle diameter of 0.1 to 3.0 μm, and these fine particles are present as aggregates of primary particles in the film, and 0.1 to 0.1 μm on the film surface. An unevenness of 3.0 μm is formed. The secondary average particle diameter is preferably 0.2 μm to 1.5 μm, more preferably 0.4 μm to 1.2 μm, and most preferably 0.6 μm to 1.1 μm. The primary and secondary particle diameters were determined by observing the particles in the film with a scanning electron microscope and determining the diameter of a circle circumscribing the particles as the particle size. In addition, 200 particles were observed at different locations, and the average value was taken as the average particle size.

As fine particles of silicon dioxide, for example, commercially available products such as Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, TT600 (manufactured by Nippon Aerosil Co., Ltd.) can be used. Zirconium oxide fine particles are commercially available, for example, under the trade names Aerosil R976 and R811 (manufactured by Nippon Aerosil Co., Ltd.), and can be used.
Among these, Aerosil 200V and Aerosil R972V are fine particles of silicon dioxide having a primary average particle diameter of 20 nm or less and an apparent specific gravity of 70 g / liter or more, and the coefficient of friction is maintained while keeping the turbidity of the optical film low. It is particularly preferable because it has a great effect of reducing the effect.

In order to obtain a film having particles having a small secondary average particle size in the present invention, several methods are conceivable when preparing a dispersion of fine particles. For example, a method of preparing a fine particle dispersion in which a solvent and fine particles are mixed with stirring in advance, adding this fine particle dispersion to a small amount of cellulose acylate solution separately prepared, stirring and dissolving, and further mixing with the main cellulose acylate dope solution There is. This method is a preferable preparation method in that the dispersibility of the silicon dioxide fine particles is good and the silicon dioxide fine particles are more difficult to reaggregate. In addition, after adding a small amount of cellulose ester to the solvent and dissolving with stirring, add the fine particles to this and disperse with a disperser to make this fine particle additive solution, and mix this fine particle additive solution with the dope solution using an in-line mixer. There is also a way to do it. Although this invention is not limited to these methods, 5-30 mass% is preferable, as for the density | concentration of silicon dioxide when silicon dioxide microparticles | fine-particles are mixed and disperse | distributed with a solvent etc., 10-25 mass% is more preferable, 15-20 Mass% is most preferred. A higher dispersion concentration is preferable because the liquid turbidity with respect to the added amount is lowered, and haze and aggregates are improved. The addition amount of the matting agent in the final cellulose acylate dope solution is preferably 0.01 to 1.0 g, more preferably 0.03 to 0.3 g, and 0.08 to 0.16 g per 1 m ^2. Most preferred.

  The solvent used is preferably lower alcohols such as methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol and the like. Although it does not specifically limit as solvents other than a lower alcohol, It is preferable to use the solvent used at the time of film forming of a cellulose ester.

(UV absorber)
The film of the present invention preferably contains an ultraviolet absorber, and the ultraviolet absorber is excellent in the ability to absorb ultraviolet rays having a wavelength of 370 nm or less from the viewpoint of preventing deterioration of the liquid crystal and from the viewpoint of good liquid crystal display properties. Those having as little absorption of visible light as possible with a wavelength of 400 nm or more are preferably used. In particular, the transmittance at a wavelength of 370 nm is desirably 10% by mass or less, preferably 5% by mass or less, and more preferably 2% by mass or less. Examples of the compounds used include oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, triazine compounds, benzophenone compounds, cyanoacrylate compounds, nickel complex compounds, and the like. It is not limited. Two or more kinds of ultraviolet absorbers may be used. The addition method to the UV absorber dope (in the present invention, the cellulose ester solution used for solution casting may be referred to as a dope) is obtained by dissolving it in an organic solvent such as alcohol, methylene chloride or dioxolane. Or may be added directly during the dope composition. For an inorganic powder that does not dissolve in an organic solvent, a dissolver or a sand mill is used in the organic solvent and cellulose ester to disperse and then added to the dope. In this invention, the usage-amount of a ultraviolet absorber is 0.1-5.0 mass% with respect to a cellulose ester, Preferably, it is 0.5-2.0 mass%, More preferably, it is 0.8-2.0. % By mass.

[Method for Producing Cellulose Acylate Film of the Present Invention]
The cellulose acylate film of the present invention can be efficiently produced by using the method for producing the cellulose acylate film of the present invention described below in detail (hereinafter also referred to as the film production method of the present invention).
The manufacturing method of the film of this invention contains the cellulose acylate satisfy | filling following formula (B), The condition which satisfy | fills following formula (A-1)-(A-3) the cellulose acylate film characterized by the above-mentioned. It is characterized by saponification treatment.
Formula (A-1): 25 ≦ T ≦ 45
(In the formula (A-1), T represents a saponification temperature (unit: ° C.).)
Formula (A-2): 0.5 ≦ S ≦ 5
(In the formula (A-2), S represents the saponification time (unit: minutes).)
Formula (A-3): 0.5 ≦ D ≦ 4.5
(In formula (A-3), D represents the alkali normality (unit: N) of the saponification solution.)
Formula (B): 2.0 ≦ DS ≦ 2.7
(In the formula (B), DS represents the acyl group substitution degree of the hydroxyl group of the glucose unit in cellulose.)
Furthermore, the method for producing a film of the present invention comprises a film-forming step of casting a dope on a support and evaporating the solvent to form a cellulose ester film, a stretching step of stretching the film, and a film obtained thereafter It is preferable to have a drying step for drying the substrate, and a step of heat-treating at a temperature of 150 to 200 ° C. for 1 minute or longer after the drying step.

(Film forming process)
As a method for producing the film of the present invention, a method for producing a known cellulose ester film can be widely adopted, and it is preferably produced by a solvent cast method. In the solvent cast method, a film can be produced using a solution (dope) in which cellulose acylate is dissolved in an organic solvent.
The organic solvent is a solvent selected from ethers having 3 to 12 carbon atoms, ketones having 3 to 12 carbon atoms, esters having 3 to 12 carbon atoms, and halogenated hydrocarbons having 1 to 6 carbon atoms. It is preferable to contain. The ether, ketone and ester may have a cyclic structure. A compound having two or more functional groups of ether, ketone and ester (that is, —O—, —CO— and —COO—) can also be used as the organic solvent. The organic solvent may have another functional group such as an alcoholic hydroxyl group. In the case of an organic 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.

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 ketones having 3 to 12 carbon atoms include acetone, methyl ethyl ketone, diethyl ketone, diisobutyl ketone, cyclohexanone and methylcyclohexanone.
Examples of the esters having 3 to 12 carbon atoms include ethyl formate, propyl formate, pentyl formate, methyl acetate, ethyl acetate and pentyl acetate.
Examples of the organic solvent having two or more kinds of functional groups include 2-ethoxyethyl acetate, 2-methoxyethanol and 2-butoxyethanol.
The number of carbon atoms of the halogenated hydrocarbon is preferably 1 or 2, and most preferably 1. The halogen of the halogenated hydrocarbon is preferably chlorine. The proportion of halogen atoms substituted by halogen in the halogenated hydrocarbon is preferably 25 to 75 mol%, more preferably 30 to 70 mol%, and more preferably 35 to 65 mol%. More preferably, it is most preferable that it is 40-60 mol%. Methylene chloride is a representative halogenated hydrocarbon.
Two or more organic solvents may be mixed and used.

A cellulose acylate solution can be prepared by a general method. The general method means that the treatment is performed at a temperature of 0 ° C. or higher (room temperature or high temperature). The solution can be prepared using a dope preparation method and apparatus in a normal solvent cast method. In the case of a general method, it is preferable to use a halogenated hydrocarbon (particularly, methylene chloride) as the organic solvent.
The amount of cellulose acylate is adjusted so as to be contained in the obtained solution in an amount of 10 to 40% by mass. The amount of cellulose acylate is more preferably 10 to 30% by mass. Arbitrary additives described later may be added to the organic solvent (main solvent).
The solution can be prepared by stirring the cellulose acylate and the organic solvent at room temperature (0 to 40 ° C.). High concentration solutions may be stirred under pressure and heating conditions. Specifically, the cellulose acylate and the organic solvent are placed in a pressure vessel and sealed, and stirred while being heated to a temperature equal to or higher than the boiling point of the solvent at normal temperature and in a range where the solvent does not boil. The heating temperature is usually 40 ° C. or higher, preferably 60 to 200 ° C., and more preferably 80 to 110 ° C.

Each component may be coarsely mixed in advance and then placed in a container. Moreover, you may put into a container sequentially. The container needs to be configured so that it can be stirred. The container can be pressurized by injecting an inert gas such as nitrogen gas. Moreover, you may utilize the raise of the vapor pressure of the solvent by heating. Or after sealing a container, you may add each component under pressure.
When heating, it is preferable to heat from the outside of the container. For example, a jacket type heating device can be used. The entire container can also be heated by providing a plate heater outside the container and piping to circulate the liquid.
It is preferable to provide a stirring blade inside the container and stir using this. The stirring blade preferably has a length that reaches the vicinity of the wall of the container. A scraping blade is preferably provided at the end of the stirring blade in order to renew the liquid film on the vessel wall.
Instruments such as a pressure gauge and a thermometer may be installed in the container. Each component is dissolved in a solvent in a container. The prepared dope is taken out of the container after cooling, or taken out and then cooled using a heat exchanger or the like.

From the prepared cellulose acylate solution (dope), a cellulose acylate film can be produced by a solvent cast method.
The dope is cast on a drum or band and the solvent is evaporated to form a film. The concentration of the dope before casting is preferably adjusted so that the solid content is 18 to 35% by mass. The surface of the drum or band is preferably finished in a mirror state. For casting and drying methods in the solvent casting method, U.S. Pat. Nos. 2,336,310, 2,367,603, 2,429,078, 2,429,297, 2,429,978, 2,607,704, 2,739,69, British Patent 6,407,331, No. 736892, JP-B Nos. 45-4554, 49-5614, JP-A-60-176834, No. 60-203430, and No. 62-1115035.

The dope is preferably cast on a drum or band having a surface temperature of 10 ° C. or less. After casting, it is preferable to dry it by applying air for 2 seconds or more. The obtained film can be peeled off from the drum or band, and further dried by high-temperature air whose temperature is successively changed from 100 ° C. to 160 ° C. to evaporate the residual solvent. The above method is described in Japanese Patent Publication No. 5-17844. According to this method, it is possible to shorten the time from casting to stripping. In order to carry out this method, it is necessary for the dope to gel at the surface temperature of the drum or band during casting.
In order to improve mechanical properties or increase the drying speed, cellulose ester film can be added. As the plasticizer, phosphoric acid ester or carboxylic acid ester is used. Examples of phosphate esters include triphenyl phosphate (TPP) and tricresyl phosphate (TCP). Representative examples of the carboxylic acid ester include phthalic acid esters and citric acid esters. Examples of phthalic acid esters include dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), dioctyl phthalate (DOP), diphenyl phthalate (DPP) and diethyl hexyl phthalate (DEHP). Examples of citrate esters include triethyl O-acetylcitrate (OACTE) and tributyl O-acetylcitrate (OACTB). Examples of other carboxylic acid esters include butyl oleate, methylacetyl ricinoleate, dibutyl sebacate, and various trimellitic acid esters. Phthalate plasticizers (DMP, DEP, DBP, DOP, DPP, DEHP) are preferably used. DEP and DPP are particularly preferred. The addition amount of the plasticizer is preferably 0.1 to 25% by mass of the amount of cellulose acylate, more preferably 1 to 20% by mass, and most preferably 3 to 15% by mass.

  Degradation inhibitors (for example, antioxidants, peroxide decomposers, radical inhibitors, metal deactivators, acid scavengers, amines) may be added to the cellulose ester film. The deterioration inhibitors are described in JP-A-3-199201, JP-A-597073, JP-A-5-194789, JP-A-5-271471, and JP-A-6-107854. The amount of the deterioration inhibitor added is 0.01 to 1 of the solution (dope) to be prepared from the viewpoint that the effect of addition of the deterioration inhibitor is manifested and that the deterioration inhibitor is prevented from bleeding out on the film surface. It is preferable that it is mass%, and it is further more preferable that it is 0.01-0.2 mass%. Examples of particularly preferred deterioration inhibitors include butylated hydroxytoluene (BHT) and tribenzylamine (TBA).

(Co-casting)
In the present invention, the obtained cellulose ester solution may be cast as a single layer liquid on a smooth band or drum as a metal support, or a plurality of cellulose ester liquids of two or more layers may be cast. Also good. When casting a plurality of cellulose ester solutions, even if a film is produced while casting and laminating a solution containing a cellulose ester from a plurality of casting openings provided at intervals in the traveling direction of the metal support, For example, the methods described in, for example, JP-A-61-158414, JP-A-1-122419, and JP-A-11-198285 can be applied. Further, it may be formed into a film by casting a cellulose ester solution from two casting ports. For example, JP-B-60-27562, JP-A-61-94724, JP-A-61-947245, This can be carried out by the methods described in JP-A Nos. 61-104813, 61-158413, and 6-134933. Also, a cellulose ester film casting method in which a flow of a high-viscosity cellulose ester solution described in JP-A-56-162617 is wrapped with a low-viscosity cellulose ester solution, and the high- and low-viscosity cellulose ester solution is simultaneously extruded. Good. Furthermore, it is also a preferred embodiment that the outer solution described in JP-A-61-94724 and JP-A-61-94725 contains a larger amount of an alcohol component which is a poor solvent than the inner solution.

  Alternatively, by using two casting ports, the film cast on the metal support is peeled off by the first casting port, and the second casting is performed on the side in contact with the metal support surface. Further, a film may be prepared, for example, a method described in Japanese Patent Publication No. 44-20235. The cellulose ester solution to be cast may be the same solution or different cellulose ester solutions and is not particularly limited. In order to give a function to a plurality of cellulose ester layers, a cellulose ester solution corresponding to the function may be extruded from each casting port. Further, the cellulose ester solution of the present invention may be cast simultaneously with other functional layers (for example, an adhesive layer, a dye layer, an antistatic layer, an antihalation layer, a UV absorbing layer, and a polarizing layer).

  In conventional single-layer liquids, it is necessary to extrude a high-concentration and high-viscosity cellulose ester solution to obtain the required film thickness. In this case, the stability of the cellulose ester solution is poor and solids are generated. In many cases, however, it becomes a problem due to a failure or poor flatness. As a solution to this, by casting multiple cellulose ester solutions from the casting port, a highly viscous solution can be extruded onto a metal support at the same time. In addition to being able to reduce the drying load by using a concentrated cellulose ester solution, the production speed of the film could be increased.

  In the case of co-casting, the inner and outer thicknesses are not particularly limited, but preferably the outer side is preferably 1 to 50% of the total film thickness, and more preferably 2 to 30%. Here, in the case of co-casting with three or more layers, the total thickness of the layer in contact with the metal support and the layer in contact with the air side is defined as the outer thickness.

  In the case of co-casting, a cellulose acylate solution having a different substitution degree can be co-cast to produce a cellulose ester film having a laminated structure. For example, a cellulose ester film having a structure of TAC layer / DAC layer / TAC layer can be formed, or a cellulose ester film having a structure of DAC layer / TAC layer / DAC layer can be formed. In addition, a cellulose ester film having a laminated structure can be produced by co-casting cellulose ester acylate solutions having different additive concentrations such as the plasticizer, the ultraviolet absorber, and the matting agent. For example, the matting agent can be contained in the surface layer in a large amount or only in the surface layer. The plasticizer and the ultraviolet absorber can be contained in the inner layer more than the surface layer, and may be contained only in the inner layer. Also, the type of plasticizer and UV absorber can be changed between the inner layer and the surface layer. For example, the surface layer contains a low-volatile plasticizer and / or UV absorber, and the inner layer has excellent plasticity. It is also possible to add a plasticizer or an ultraviolet absorber excellent in ultraviolet absorption. Moreover, it is also a preferable aspect that a release agent is included only in the surface layer on the metal support side. Moreover, in order to cool a metal support body by a cooling drum method and to gelatinize a solution, it is also preferable to add more alcohol which is a poor solvent to a surface layer than an internal layer. The Tg of the surface layer and the inner layer may be different, and the Tg of the inner layer is preferably lower than the Tg of the surface layer. Further, the viscosity of the solution containing the cellulose ester during casting may be different between the surface layer and the inner layer, and the viscosity of the surface layer is preferably smaller than the viscosity of the inner layer. It may be smaller than the viscosity.

(Drying process, stretching process)
A method for drying a web that has been dried on a drum or belt and peeled off will be described. The web peeled at the peeling position just before the drum or belt makes one round is conveyed by alternately passing through a group of rolls arranged in a staggered manner, or the both ends of the peeled web are gripped by clips or the like and are not contacted. It is conveyed by the method of conveying it automatically. Drying is performed by a method of applying wind at a predetermined temperature to both sides of the web (film) being conveyed or a method using a heating means such as a microwave. Since rapid drying may impair the flatness of the film to be formed, it is preferable to dry at a temperature at which the solvent does not foam in the initial stage of drying, and to dry at a high temperature after the drying proceeds. In the drying process after peeling from the support, the film tends to shrink in the longitudinal direction or the width direction by evaporation of the solvent. Shrinkage increases with drying at higher temperatures. Drying while suppressing this shrinkage as much as possible is preferable for improving the flatness of the finished film. From this point, for example, as shown in Japanese Patent Laid-Open No. 62-46625, a method in which all or part of the drying process is performed while holding the width at both ends of the web with clips or pins in the width direction. (Tenter method) is preferable. It is preferable that the drying temperature in the said drying process is 100-145 degreeC. Although the drying temperature, the amount of drying air, and the drying time differ depending on the solvent used, it may be appropriately selected according to the type and combination of the solvents used. In the production of the film of the present invention, the web (film) peeled from the support is preferably stretched when the amount of residual solvent in the web is less than 120% by mass.

The residual solvent amount can be expressed by the following formula.
Residual solvent amount (% by mass) = {(MN) / N} × 100
Here, M is the mass of the web at an arbitrary point in time, and N is the mass when the web of which M is measured is dried at 110 ° C. for 3 hours. If the amount of residual solvent in the web is too large, the effect of stretching cannot be obtained, and if it is too small, stretching becomes extremely difficult and the web may break. The more preferable range of the residual solvent amount in the web is 70% by mass or less, more preferably 10% by mass to 50% by mass, and particularly preferably 12% by mass to 35% by mass. Further, if the stretching ratio is too small, a sufficient phase difference cannot be obtained, and if it is too large, stretching may become difficult and breakage may occur.
The draw ratio is preferably 1.1 to 1.5, and more preferably 1.15 to 1.4. The stretching may be performed in the longitudinal direction, in the transverse direction, or in both directions, preferably at least in the longitudinal direction. By setting the draw ratio to 10% or more, Re can be expressed more appropriately, and the bowing can be improved. Moreover, haze can be reduced by making a draw ratio into 50% or less.
In the present invention, the solution cast film can be stretched without being heated to a high temperature as long as the residual solvent amount is in a specific range, but it is preferable because drying and stretching can shorten the process. . However, since the plasticizer volatilizes when the temperature of the web is too high, a range of room temperature (15 ° C) to 145 ° C or less is preferable. Further, stretching in the biaxial directions perpendicular to each other is an effective method for bringing the refractive indexes Nx, Ny, and Nz of the film within the scope of the present invention. For example, when stretching in the casting direction, if the shrinkage in the width direction is too large, the value of Nz becomes too large. In this case, it can be improved by suppressing the width shrinkage of the film or stretching in the width direction. When stretching in the width direction, the refractive index may be distributed with a width. This is sometimes seen when using, for example, the tenter method, but it is a phenomenon that occurs when the film is stretched in the width direction and contraction force is generated at the center of the film and the end is fixed. It is thought to be called the Boeing phenomenon. Even in this case, by stretching in the casting direction, the bowing phenomenon can be suppressed, and the distribution of the width retardation can be improved. Furthermore, the film thickness fluctuation | variation of the film obtained by extending | stretching to the biaxial direction orthogonal to each other can be reduced. If the film thickness variation of the optical film is too large, the retardation will be uneven. The film thickness variation of the optical film is preferably in the range of ± 3%, and more preferably ± 1%. For the purposes as described above, a method of stretching in the biaxial directions orthogonal to each other is effective, and the stretching ratios in the biaxial directions orthogonal to each other are 1.2 to 2.0 times and 0.7 to 1.0, respectively. It is preferable that the range be doubled. Here, stretching to 1.2 to 2.0 times with respect to one direction and making the other perpendicular to 0.7 to 1.0 times means that the distance between the clip or pin supporting the film is This means that the distance is 0.7 to 1.0 times the interval before stretching.

In general, when a biaxial stretching tenter is used to stretch in the width direction so as to have an interval of 1.2 to 2.0 times, a contracting force acts in the longitudinal direction, which is the perpendicular direction.
Therefore, if the force is applied in only one direction and the stretching is continued, the width in the perpendicular direction is reduced, but this means that the amount of shrinkage is suppressed with respect to the amount that shrinks without restricting the width. This means that the interval between the clip or pin whose width is restricted is restricted to a range of 0.7 to 1.0 times that before stretching. At this time, in the longitudinal direction, a force is exerted to shrink the film by stretching in the width direction. By taking the interval between the clips or pins in the longitudinal direction, an excessive tension is not applied in the longitudinal direction. There is no particular limitation on the method of stretching the web. For example, a method in which a difference in peripheral speed is applied to a plurality of rolls, and the roll peripheral speed difference is used to stretch in the longitudinal direction, the both ends of the web are fixed with clips and pins, and the interval between the clips and pins is increased in the traveling direction. And a method of stretching in the vertical direction, a method of stretching in the horizontal direction and stretching in the horizontal direction, a method of stretching in the vertical and horizontal directions and stretching in both the vertical and horizontal directions, and the like. Of course, these methods may be used in combination. In the case of the so-called tenter method, driving the clip portion by a linear drive method is preferable because smooth stretching can be performed and the risk of breakage and the like can be reduced.

(Heat treatment process)
The film production method of the present invention is preferably provided with a heat treatment step after the drying step. The heat treatment in the heat treatment step may be performed after completion of the drying step, and may be performed immediately after the stretching / drying step. Alternatively, after the completion of the drying step, the material may be wound once by a method described later, and only the heat treatment step may be separately provided. . In the present invention, it is preferable to provide the heat treatment step again after the drying step is once cooled to room temperature to 100 ° C. or less. This is because a film having better thermal dimensional stability can be obtained. For the same reason, it is preferable that the amount of residual solvent is dried to less than 2% by mass, preferably less than 0.4% by mass immediately before the heat treatment step.
Although the reason why the shrinkage rate of the film can be reduced by such treatment is not clear, in the film that has undergone the treatment to be stretched in the stretching process, the residual stress in the stretching direction is large, so the residual stress is eliminated by heat treatment. Thus, it is presumed that the shrinkage force in the region below the heat treatment temperature is reduced.

The heat treatment is performed by a method of applying a wind at a predetermined temperature to the film being conveyed or a method using a heating means such as a microwave.
The heat treatment is preferably performed at a temperature of 150 to 200 ° C., more preferably 160 to 180 ° C. The heat treatment is preferably performed for 1 to 20 minutes, more preferably 5 to 10 minutes.
When the heat treatment temperature exceeds 200 ° C. for a long time, it may cause a problem because the amount of the plasticizer scattered in the film increases.

  In the heat treatment step, the film tends to shrink in the longitudinal direction or the width direction. It is preferable to heat-treat while suppressing the shrinkage as much as possible in order to improve the flatness of the finished film, and a method in which the width ends of the web are held with clips or pins in the width direction (tenter method). Is preferred. Furthermore, it is preferable to extend | stretch 0.9 to 1.5 times in the width direction and conveyance direction of a film, respectively.

  As the winder for winding the obtained film, a commonly used winder can be used, such as a constant tension method, a constant torque method, a taper tension method, and a program tension control method with a constant internal stress. It can be wound up by a take-up method. In the optical film roll obtained as described above, the slow axis direction of the film is preferably ± 2 ° with respect to the winding direction (longitudinal direction of the film), and further within the range of ± 1 °. Preferably there is. Alternatively, it is preferably ± 2 degrees with respect to the direction perpendicular to the winding direction (film width direction), and more preferably within a range of ± 1 degree. In particular, the slow axis direction of the film is preferably within ± 0.1 degrees with respect to the winding direction (longitudinal direction of the film). Alternatively, it is preferably within ± 0.1 degrees with respect to the width direction of the film.

(Alkaline saponification treatment)
In the method for producing a film of the present invention, a cellulose acylate film containing a cellulose acylate satisfying the following formula (B) is saponified under conditions satisfying the following formulas (A-1) to (A-3). Features.
Formula (A-1): 25 ≦ T ≦ 45
(In the formula (A-1), T represents a saponification temperature (unit: ° C.).)
Formula (A-2): 0.5 ≦ S ≦ 5
(In the formula (A-2), S represents the saponification time (unit: minutes).)
Formula (A-3): 0.5 ≦ D ≦ 4.5
(In formula (A-3), D represents the alkali normality (unit: N) of the saponification solution.)
Formula (B): 2.0 ≦ DS ≦ 2.7
(In the formula (B), DS represents the acyl group substitution degree of the hydroxyl group of the glucose unit in cellulose.)
Moreover, it is preferable that the cellulose acylate film before the saponification treatment has a laminated structure of two or more. Further, at least one layer of the cellulose acylate film before the saponification treatment contains a cellulose acylate satisfying the formula (B), and is different from the layer containing the cellulose acylate satisfying the formula (B). It is preferable that at least one layer contains cellulose acylate satisfying the formula (C). Further, the cellulose acylate film before the saponification treatment has a laminated structure of 3 or more, at least one inner layer contains cellulose acylate satisfying the formula (B), and both surface layers have the formula It is preferable to contain a cellulose acylate that satisfies (C). Furthermore, it is preferable that the film thickness of at least one surface layer of the cellulose acylate film before the saponification treatment is 0.5 to 5 μm. Also for the cellulose acylate film having such a laminated structure, the saponification treatment in the production method of the present invention can be preferably used.

It is one of the features of the present invention that the saponification treatment temperature is milder than the conventional saponification conditions for TAC. By making the saponification treatment temperature 45 ° C. or less, the surface condition of the film is remarkably improved. be able to. Moreover, the contact angle of water can be made into the preferable range of this invention by making saponification process temperature into 25 degreeC or more.
The saponification temperature is preferably 25 to 45 ° C, particularly preferably 30 to 45 ° C.

By setting the saponification treatment time to 0.5 minutes or more, the contact angle of water can be within the preferred range of the present invention. By making the saponification treatment time 5 minutes or less, the surface condition of the film can be remarkably improved, and the haze can be further reduced. Will be improved.
The saponification treatment time is preferably 1 to 5 minutes, more preferably 1.5 to 5 minutes, particularly preferably 2 to 5 minutes, and further preferably 2 to 4 minutes.

The difference between the temperature of the saponification solution at the start of saponification for the cellulose acylate film and the temperature of the saponification solution at the end of saponification is preferably 0.1 ° C. or more, more preferably 0.5 to 20 ° C., More preferably, it is 3-10 degreeC. In order to realize such a temperature difference, the difference between the saponification solution temperature near the entrance where the film is immersed in the saponification solution bath and the saponification solution temperature near the exit where the film is removed from the saponification solution is preferably 0. .1 ° C. or higher, more preferably 0.5 to 20 ° C., and even more preferably 3 to 10 ° C. Specifically, it can be set using a method such as providing a partition plate in the alkaline solution tank to prevent the flow of the solution and adding a heater for raising the temperature. At this time, the temperature at the end of saponification (temperature near the outlet) is preferably higher. Thereby, precipitation of the additive in a film can be suppressed and the contact angle of a film can be reduced efficiently.
The additive of the cellulose acylate film dissolved in the liquid may adhere to the cellulose acylate film and cause a bright spot failure (foreign substance defect). For this reason, the method of adsorb | sucking and removing an elution component using activated carbon can be utilized preferably. Activated carbon only needs to have a function of removing colored components in the saponification solution, and there is no limitation on the form, material, and the like. Specifically, a method of directly putting activated carbon into an alkaline saponification solution tank may be adopted, or a method of circulating a saponification solution between a saponification solution tank and a purifier filled with activated carbon may be adopted.

In the film production method of the present invention, it is preferable that the saponification treatment includes a saponification step using an alkaline saponification solution for allowing the saponification reaction to proceed, and a step of slowing or stopping the saponification reaction. Further, it is preferable that the step of slowing or stopping the saponification reaction is a dilution step or a neutralization step. That is, it is preferable to include a step of washing off the alkaline solution from the film. The method for producing a film of the present invention may include a step of washing off an alkali solution with an alkali diluent, a step of neutralizing an alkali solution with an alkali neutralization solution, and a step of washing off the alkali neutralization solution from the film. They can be implemented in combination or all of them at the same time. In addition, there is no restriction | limiting in particular about the order which implements these, unless it is contrary to the meaning of this invention.
In the method for producing a film of the present invention, the saponification treatment step, the dilution step with an alkali diluent (preferably water), and the neutralization step with an alkali neutralization solution (preferably an acidic solution) are performed in this order. From the viewpoint of performance stability, it is more preferable. Furthermore, it is more preferable to implement the water washing process by water after that. Moreover, it is more preferable to perform a drying process after that.

  Moreover, it is preferable to implement these processes, conveying a film. The conveyance speed of the cellulose acylate film is determined by the combination of the composition of the alkali saponification solution and the saponification method.

For the step of treating the cellulose acylate film with the alkali saponification solution, any conventionally known method may be used, and examples thereof include a dipping method, a spraying method, and a coating method. For example, a method of immersing in an alkaline solution as described in JP-A-2001-188130 may be used, or a method of applying an alkaline solution as described in JP-A-2004-203965 may be used. Good. In particular, when only one surface of the film is uniformly saponified without unevenness, a coating method is preferable. As a coating method, a conventionally known coating method can be used as described later.
In the case of the saponification step immersed in an alkaline solution, the saponification solution is preferably convected in a saponification solution tank. The convection speed can be measured from the amount of the string drawn out per unit time by putting a float having the same specific gravity as the solution in which the string is attached to the solution, and the linear velocity is preferably 1 m / min or more. 10 to 1000 m / min, more preferably 30 to 500 m / min, and most preferably 50 to 300 m / min. Convection of the saponification solution can be carried out with stirring blades in the solution tank.

In the film production method of the present invention, the saponification treatment is performed using an alkaline solution as a saponification solution. The saponification solution is composed of an alkaline agent and water, and may optionally contain a surfactant and a compatibilizing agent.
The concentration of the alkaline solution (content of the alkaline agent in the alkaline solution) needs to be determined according to the acyl substitution degree of the cellulose acylate. That is, in cellulose acylate, the saponification efficiency is significantly reduced as the carbon number of the acyl group increases, so the alkali concentration needs to be increased as the carbon number of the acyl group increases, but if the alkali concentration is too high, Since the stability of the alkaline solution is impaired and sometimes precipitated during long-time application, it is important to select an alkaline solution appropriately according to the primary structure of cellulose acylate. Therefore, the alkali solution used in the present invention has a normality of 0.5 to 4.5N, more preferably 1 to 4.5N, and particularly preferably 1.5 to 4N. Moreover, the density | concentration of an alkaline solution can also be adjusted according to the kind of alkaline agent to be used, reaction temperature, and reaction time within this range.

Alkaline agents include tribasic sodium phosphate, tribasic potassium phosphate, tertiary ammonium phosphate, dibasic sodium phosphate, dibasic potassium phosphate, dibasic ammonium phosphate, ammonium carbonate, ammonium bicarbonate, sodium borate And inorganic alkali agents such as potassium borate, ammonium borate, sodium hydroxide, potassium hydroxide, lithium hydroxide, and ammonium hydroxide. In addition, monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoisopropylamine, diisopropylamine, triisopropylamine, n-butylamine, monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, Ethyleneimine, ethylenediamine, pyridine, DBU (1,8-diazabicyclo [5,4,0] -7-undecene), DBN (1,5-diazabicyclo [4,3,0] -5-nonene), tetramethylammonium Hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, triethylbutylammonium Organic alkali agents such as Dorokishido be used. These alkali agents can be used alone or in combination of two or more thereof, and a part of them may be added in the form of a salt such as a halogenated salt.
Among these alkali agents, sodium hydroxide and potassium hydroxide are preferable. The reason is that the pH can be adjusted in a wide pH range by adjusting these amounts.

  The solvent of the alkaline solution is a single solvent of water or a mixed solvent of water and an organic solvent. Preferred organic solvents include alcohols, alkanols, monoethers of glycol compounds, ketones, amides, sulfoxides, ethers, more preferably alcohols having a molecular weight of 61 or more, more preferably molecular weights. 61 or more glycols, specifically, ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, glycerol monomethyl ether, glycerol monoethyl ether, cyclohexanediol, cyclohexanedimethanol, diethylene glycol, dipropylene glycol, etc. Is mentioned. You may use the organic solvent used together with water individually or in mixture of 2 or more types.

When at least one organic solvent is used alone or in combination of two or more organic solvents, those having high solubility in water are preferable. The solubility of water in the organic solvent is preferably 50% by mass or more, and more preferably freely mixed with water. An alkaline solution having sufficient solubility in an alkali agent, a salt of a fatty acid by-produced by a saponification treatment, a carbonate salt generated by absorbing carbon dioxide in the air, and the like can be prepared.
The use ratio of the organic solvent in the solvent is determined according to the type of solvent, miscibility with water (solubility), reaction temperature and reaction time. In order to complete the saponification reaction in a short time, it is preferable to prepare a solution at a high concentration. However, if the solvent concentration is too high, components (such as a plasticizer) in the acylate film may be extracted, or excessive swelling of the film may occur, and it is necessary to select appropriately.
The mixing ratio of water and organic solvent is preferably 3/97 to 85/15 mass ratio. More preferably, it is 5 / 95-60 / 40 mass ratio, More preferably, it is 15 / 85-40 / 60 mass ratio. In this range, the entire film surface can be easily saponified uniformly without impairing the optical properties of the acylate film.

Like the alkaline solution preferably used in the present invention, the high-concentration alkaline solution absorbs CO ₂ in the environmental atmosphere and becomes carbonic acid in the solution, lowering the pH and easily generating carbonate precipitates. The CO ₂ concentration is preferably 5000 ppm or less. In order to suppress the absorption of CO _{2 in} the environmental atmosphere, it is more preferable that the coating solution coater of the alkaline solution has a semi-hermetic structure or is covered with dry air, an inert gas, or an organic solvent saturated vapor of the alkaline solution.

  The alkaline solution used in the present invention may contain a surfactant. By adding the surfactant, even if the organic solvent extracts the film-containing material, it is stably present in the alkaline solution, and the extracted material does not precipitate and solidify in the subsequent water washing step. The surfactant preferably used is described in, for example, JP-A No. 2003-313326.

  The alkaline solution used in the present invention may contain an antifoaming agent, and the antifoaming agent preferably used is described in, for example, JP-A-2003-313326.

  The alkaline solution used in the present invention may contain an antifungal agent and / or an antibacterial agent. Examples of the antifungal agent / antibacterial agent preferably used are described in, for example, JP-A No. 2003-313326. Have been described.

In addition, as water used for the alkaline solution, the Japanese Waterworks Law (Act No. 177 of 1957) and the ministerial ordinance on the water quality standards based on it (August 31, 1978 Ministry of Health and Welfare Ordinance No. 56), Based on Law No. 125 of July 10, 2011 and its separate table) and the influence on each element, mineral, etc. in the state of mixing in water prescribed by the WHO regulated tap water standard is preferable.
In order to more reliably achieve the effect of the present invention, it is preferable to use the water described above, and the calcium concentration of the alkaline solution is preferably 0.001 to 400 mg / L, and 0.001 to 150 mg / L. Is more preferable, and 0.001 to 10 mg / L is particularly preferable. The magnesium concentration is preferably 0.001 to 400 mg / L, more preferably 0.001 to 150 mg / L, and particularly preferably 0.001 to 10 mg / L. It is preferable that other polyvalent metal ions other than calcium and magnesium are not included. The concentration of the polyvalent metal ion is preferably 0.002 to 1000 mg / L. On the other hand, it is preferable that the alkali solution does not contain anions such as chloride ions and carbonate ions. The chloride ion concentration is preferably 0.001 to 500 mg / L, more preferably 0.001 to 300 mg / L, and particularly preferably 0.001 to 100 mg / L. Moreover, it is preferable that carbonate ions are not included. The carbonate ion concentration is preferably 0.001 to 3500 mg / L, more preferably 0.001 to 1000 mg / L, and particularly preferably 0.001 to 200 mg / L. In these concentration ranges, generation of insoluble matter in the solution is suppressed.

  The method for saponifying a cellulose acylate film preferably includes a step of heating the cellulose acylate film to room temperature or higher in advance, and for the treatment of saponifying the cellulose acylate film with an alkaline saponification solution at a surface temperature of room temperature or higher. Examples include a step of heating to a room temperature or higher before immersing in an alkali saponification solution, a step of preheating an alkaline solution, or a combination of these. It is preferable to combine with the step of heating to room temperature or higher before dipping in the alkaline saponification solution.

  In the step of previously heating the cellulose acylate film to room temperature or higher, direct heating by hot air collision (blowing), contact heat transfer by a heating roll, induction heating by microwaves, radiant heat heating by an infrared heater, or the like can be preferably used. In particular, contact heat transfer using a heating roll is preferable in terms of high heat transfer efficiency and a small installation area, and fast rise in film temperature at the start of conveyance. A general double jacket roll or electromagnetic induction roll (manufactured by Tokuden) can be used.

  Also, before the step of heating the cellulose acylate film above room temperature or the step of applying the alkali saponification solution to the cellulose acylate film, dust is removed and the wettability of the membrane surface is made more uniform. For this purpose, a generally known method can be used as the method for removing the charge, removing the dust, or performing the wet treatment. As the charge removal method, the method described in JP-A-62-1131500 can be used. As a method for removing dust, the method described in JP-A-2-43157 can be exemplified.

  In the saponification step, when a polymer film containing an additive is saponified, the additive is eluted into the saponification solution, resulting in an increase in the haze of the film after saponification. Therefore, when saponifying a polymer film containing an additive having a high elution property to the saponification solution, various saponification conditions such as treatment temperature, treatment time, alkalinity of the saponification solution are appropriately adjusted, and the additive It is necessary to suppress elution into the saponification solution as much as possible.

  The saponification treatment method of the present invention is also effective when saponifying a polymer film containing an additive having a large saponification solution elution amount.

  By setting the carbonate ion concentration of the alkali dilution liquid and the alkali neutralization liquid to 3500 mg / L or less, it is possible to effectively prevent the deposit from adhering to the film surface. More preferably, it is 1000 mg / L or less, Most preferably, it is 100 mg / L or less. By setting the carbonate ion concentration to 3500 mg / L or less, an orientation film is applied to a saponified cellulose acylate film, and after rubbing, foreign matter defects are caused when an optical anisotropic layer is formed by liquid crystalline molecules. And orientation defects can be reduced.

There are two main methods for slowing or stopping the saponification reaction between the alkali saponification solution and the cellulose acylate film after the saponification reaction has proceeded. The first method is to dilute the applied alkali saponification solution to lower the alkali concentration and reduce the reaction rate, and the second method is to adjust the temperature of the cellulose acylate film to which the alkali saponification solution is applied. This is a method of lowering the reaction rate.
The method using an alkali diluting solution and the method using an alkali neutralizing solution are also part of the step of washing off the alkali saponification solution from the film as already described.

(1) Method using a diluting solution In order to dilute the applied alkali saponification solution, a method of applying a diluting solution (also referred to as an alkali diluting solution), a method of spraying the diluting solution, a cellulose acid container in a container containing the diluting solution. A method of immersing the whole rate film can be adopted. In the manufacturing method of this invention, the method of immersing the whole cellulose acylate film in the container containing a diluent is preferable.

The purpose of the alkaline diluting solution is to reduce the alkali concentration and prevent the extraction material such as the film-added substance from adhering to the film, so it must be a solvent that dissolves the alkaline agent in the alkaline saponification solution. Therefore, it is preferable to use water or a mixed solution of water and an organic solvent, and two or more organic solvents may be mixed and used. The organic solvent used in the alkali saponification solution described later can be used advantageously. In the production method of the present invention, the preferred solvent is water, and the temperature during washing is preferably about room temperature.
In addition, it is also preferable to include a surfactant in the alkaline diluent so that an extraction material such as a film additive substance does not adhere to the film. Although there is no limitation in particular as surfactant, the surfactant used for the alkali saponification solution mentioned later can be utilized advantageously. Further, it is preferable to add an antifoaming agent to the alkali diluted solution because fine bubbles are not attached to the surface of the film, and the alkali saponification solution and the alkali diluted solution can be washed uniformly without unevenness.

(2) Method using neutralization solution An acid can also be used to quickly stop the saponification reaction with alkali. In order to neutralize with a small amount, it is preferable to use a strong acid. Furthermore, considering the ease of washing with water, it is preferable to select an acid having a high solubility in water for the salt produced after the neutralization reaction with the alkali. In the production method of the present invention, hydrochloric acid, nitric acid, phosphoric acid, chromic acid, sulfonic acid, methanesulfonic acid, and sulfuric acid are more preferable, and sulfuric acid is particularly preferable.
If the carbonate ion concentration or chloride ion concentration in the alkali saponification solution is high, precipitation may occur due to a rapid neutralization reaction. In this case, a buffering weak acid is added to the alkali neutralization solution. It is preferable. Examples of such weak acids include sugars such as sorbitol, saccharose, glucose, galactose, arabinose, xylose, fructose, ribose, mannose, and L-ascorbic acid described in IONATION CONSTANTS OF ORGANICS AS ORGANS A ORDERS SOLUTION published by Pergamon Press. , Aldehydes, compounds having phenolic hydroxyl groups, oximes, nucleic acid-related substances, and the like. In the production method of the present invention, it is preferable to use about 0.1 N sulfuric acid.
Moreover, in the manufacturing method of this invention, it is preferable that the temperature of the neutralization liquid to be used is about 30 degreeC.

  In order to neutralize the applied alkali saponification solution with an acid, a method of applying an acid solution (an alkali neutralization solution), a method of spraying an acid solution, or immersing the cellulose acylate film together in a container containing the acid solution The method can be adopted. The method of applying an acid solution and the method of spraying are preferable when the cellulose acylate film is continuously conveyed. The method of applying the acid solution is most preferable because it can be carried out using the minimum necessary acid solution. Among these, in the production method of the present invention, a method of immersing the cellulose acylate film together in a container containing an acid solution is preferable in the neutralization step.

  The application of the alkali neutralization solution is desirably a continuous application method in which the acid solution can be applied again onto the cellulose acylate film to which the alkali saponification solution has already been applied. For coating, a die coater (extrusion coater, slide coater), roll coater (forward roll coater, reverse roll coater, gravure coater), and rod coater (rod wound with a thin metal wire) can be preferably used. The coating method is described in various documents (for example, Modern Coating and Drying Technology, Edward Cohen and Edgar B. Gutoff, Edits., VCH Publishers, Inc, 1992). In order to reduce the alkalinity by quickly mixing the alkali saponification solution and the neutralizing solution, the die coater in which the flow is laminar in the micro area (sometimes called coating bead) where the neutralizing solution is applied A roll coater or a rod coater in which the flow is not uniform is more preferable.

  The coating amount of the alkali neutralizing solution is determined according to the type of alkali and the concentration of the alkali saponification solution. In the case of a die coater in which the flow in the coating bead is a laminar flow, the coating amount of the neutralizing solution is preferably 0.1 to 5 times the original alkali coating amount, and is 0.5 to 2 times. Further preferred. In the case of a roll coater or a rod coater, since the flow in the coating bead is not uniform, the alkali saponification solution and the neutralizing solution are mixed, and the mixed solution is re-coated. Therefore, in this case, since the neutralization rate cannot be specified by the application amount of the neutralization liquid, it is necessary to measure the alkali concentration after application of the neutralization liquid. In a roll coater or a rod coater, the coating amount of the acid solution is preferably determined such that the pH after application of the acid solution is 4 to 9, and more preferably 6 to 8.

The purpose of the alkali neutralization solution is to reduce the alkalinity and prevent the extraction materials such as film additive substances from adhering to the film. I must. Therefore, it is preferable to use water or a mixed solution of water and an organic solvent, and two or more organic solvents may be mixed and used. The organic solvent used for the alkali saponification solution mentioned later can be used significantly. A preferred solvent is water.
Moreover, it is preferable to include a surfactant in the alkali neutralization solution so that an extraction material such as a film additive substance does not adhere to the film. Although there is no limitation in particular as surfactant, the surfactant used for the alkali saponification solution mentioned later can be utilized advantageously. Furthermore, it is preferable that the alkali neutralizing solution contains a buffering agent described later in order to increase the cleaning efficiency.

Further, the alkali agent or film additive substance concentrated by adjusting the chloride ions and the polyvalent metal ions such as calcium ions and magnesium ions in the alkali dilution solution and the alkali neutralization solution to 300 mg / L or less and 500 mg / L or less, respectively. Optical anisotropy when an optically anisotropic layer of liquid crystalline molecules is installed after applying an alignment film to a saponified cellulose acylate film without rubbing the extraction material on the film surface and performing rubbing treatment It is possible to reduce poor adhesion of layers.
As described later, it is preferable to use water or a liquid composed of water and an organic solvent as the alkali dilution liquid or alkali neutralization liquid. However, the water used is preferably pure water, and the concentration of calcium in the liquid is: It is preferably 0.001 to 100 mg / L, more preferably 0.001 to 50 mg / L, and particularly preferably 0.001 to 10 mg / L. The magnesium concentration is preferably 0.001 to 50 mg / L, more preferably 0.001 to 30 mg / L, and particularly preferably 0.001 to 10 mg / L. No polyvalent metal ions other than calcium and magnesium, such as Be, Sr, Ba, Al, Sn, Pb, Ti, Cr, Mn, Fe, Co, Ni, Cu (II), Co, Zn Is preferred. The concentration of the polyvalent metal ion is preferably 0.002 to 150 mg / L.

The washing step is performed in order to remove the alkali saponification solution and the alkali dilution solution or alkali neutralization solution. If extraction materials such as alkali agents, acids, salts, and film additives remain in these materials, the saponification reaction proceeds, the formation of a coating film for the alignment film and the liquid crystalline molecular layer to be applied later, and the alignment of the liquid crystal molecules It may affect.
The washing can be performed by a method of applying washing water, a method of spraying washing water, or a method of immersing the cellulose acylate film together in a container containing washing water. In the production method of the present invention, a method of immersing the cellulose acylate film together in a container containing cleaning water is preferable.

  It is preferable to use pure water as the washing water. The pure water used in the present invention has a specific electric resistance of at least 0.1 MΩ · cm or more, particularly metal ions such as sodium, potassium, magnesium and calcium are less than 1 mg / L, and anions such as chloro ion and nitrate ion. Is preferably less than 0.1 mg / L. Pure water can be obtained by a simple substance such as a reverse osmosis membrane, an ion exchange resin, distillation, or a combination thereof.

  The higher the washing water temperature, the higher the washing ability. However, in the method of spraying water on the cellulose acylate film to be transported, the area of the water in contact with the air is large, and the higher the temperature is, the more the evaporation becomes. As a result, the surrounding humidity increases and the risk of dew condensation increases. For this reason, in the manufacturing method of this invention, it is preferable to set the temperature of washing water to about room temperature.

  If the components of the alkaline saponification solution or the product of the saponification reaction are not easily dissolved in water, a solvent washing step for removing water-insoluble components may be added before or after the water washing step. The solvent washing step can utilize the water washing method and draining means described above. As the organic solvent to be used, in addition to the solvent that can be used in the alkali saponification solution described later, the solvents described in the new edition solvent pocket book (Ohm, published in 1994) can be used.

  A drying step can also be performed after the washing step. Usually, the water film can be sufficiently removed by means of draining water such as an air knife, and a drying step may not be necessary. However, before the cellulose acylate film is wound into a roll, it is heated to adjust to a preferred water content. It may be dried. Conversely, the humidity can be adjusted with a wind having a set humidity. The temperature of the drying air is preferably 30 to 200 ° C, more preferably 40 to 150 ° C, and particularly preferably 50 to 120 ° C.

[Polarizer]
The polarizing plate of the present invention is characterized in that at least one of the protective films is the film of the present invention, in which a protective film is bonded to both sides of the polarizer. That is, the film of this invention is used for the protective film for polarizing plates. As described above, the polarizing plate is formed by laminating and laminating a protective film on at least one surface of the polarizer. A conventionally known polarizer can be used. For example, a hydrophilic polymer film such as a polyvinyl alcohol film is treated with a dichroic dye such as iodine and stretched. The bonding of the cellulose ester film and the polarizer is not particularly limited, but can be performed with an adhesive made of an aqueous solution of a water-soluble polymer. The water-soluble polymer adhesive is preferably a completely saponified polyvinyl alcohol aqueous solution.
In particular, a polarizing plate using the film of the present invention has little deterioration under high temperature and high humidity conditions and can maintain stable performance for a long time.

[Liquid Crystal Display]
The polarizing plate of the present invention has the polarizing plate of the present invention. When the film of the present invention is used as a protective film for polarizing plate, the protective film for polarizing plate / polarizer / protective film for polarizing plate / liquid crystal cell / protective film for polarizing plate of the present invention / polarizer / protective film for polarizing plate. It can preferably be used in the configuration, or a protective film for polarizing plate / polarizer / protective film for polarizing plate of the present invention / liquid crystal cell / protective film for polarizing plate of the present invention / polarizer / protective film for polarizing plate. In particular, by bonding to a liquid crystal cell such as a TN type, a VA type, or an OCB type, it is possible to provide a display device that is further excellent in viewing angle and visibility with little coloring.
The liquid crystal display device of the present invention is particularly preferably in the VA mode from the viewpoint that the film of the present invention expresses Re and Rth within the above preferred ranges.
The cellulose ester film of the present invention and the polarizing plate using the film can be used for liquid crystal cells and liquid crystal display devices in various display modes. TN (Twisted Nematic), IPS (In-Plane Switching), FLC (Ferroelectric Liquid Crystal), AFLC (Anti-Ferroly Liquid Liquid Crystal), OCB (Optically Charged Tunds). Various display modes such as HAN (Hybrid Aligned Nematic) have been proposed.

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

  The VA mode liquid crystal display device includes a liquid crystal cell and two polarizing plates disposed on both sides thereof. The liquid crystal cell carries a liquid crystal between two electrode substrates. In one aspect of the transmission type liquid crystal display device of the present invention, the film of the present invention is disposed between the liquid crystal cell and one polarizing plate, or between the liquid crystal cell and both polarizing plates. Arrange two.

  In another aspect of the transmissive liquid crystal display device of the present invention, an optical compensation sheet made of the film of the present invention is used as a transparent protective film for a polarizing plate disposed between a liquid crystal cell and a polarizer. The above optical compensation sheet may be used only for the protective film (between the liquid crystal cell and the polarizer) of one polarizing plate, or two (between the liquid crystal cell and the polarizer) of both polarizing plates. You may use said optical compensation sheet for a sheet of protective film. When the optical compensation sheet is used for only one polarizing plate, it is particularly preferable to use it as a protective film for the liquid crystal cell side of the backlight side polarizing plate of the liquid crystal cell. For the lamination to the liquid crystal cell, the film of the present invention is preferably on the VA cell side. The protective film may be a normal cellulose ester film, and is preferably thinner than the film of the present invention. For example, it is preferably 40 to 80 μm, and examples thereof include, but are not limited to, commercially available KC4UX2M (40 μm manufactured by Konica Capto), KC5UX (60 μm manufactured by Konica Caputo), TD80 (80 μm manufactured by Fuji Film), and the like.

  The features of the present invention will be described more specifically with reference to examples and comparative examples. The materials, amounts used, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the specific examples shown below.

(Preparation of cellulose acylate)
Cellulose acylates having different types of acyl groups and different degrees of substitution described in Table 3 were prepared. This was carried out by adding sulfuric acid (7.8 parts by mass with respect to 100 parts by mass of cellulose) as a catalyst, adding carboxylic acid as a raw material for the acyl substituent, and carrying out an acylation reaction at 40 ° C. At this time, the kind and substitution degree of the acyl group were adjusted by adjusting the kind and amount of the carboxylic acid. In addition, aging was performed at 40 ° C. after acylation. Further, the low molecular weight component of the cellulose acylate was removed by washing with acetone. In the types of cellulose acylates in the table, CAB is an abbreviation for cellulose acetate butyrate (a cellulose ester derivative in which an acyl group is composed of an acetyl group and a butyryl group), and CAP is a cellulose acetate propionate ( An abbreviation for cellulose ester derivatives in which the acyl group is composed of an acetyl group and a propionyl group), and CA means cellulose acetate (a cellulose ester derivative in which the acyl group is composed only of an acetyl group). Further, the degree of substitution DSA in the table indicates the degree of substitution derived from the acetyl group, and the degree of substitution DSB indicates the degree of substitution of the substituent described in the column of “Substituent types” in the table. Here, Pr represents a propionyl group, and Bu represents a butyryl group. Moreover, in Table 3, the additive described in the column of the type of additive represents the additive described in Table 4 below, BDP represents biphenyl diphenyl phosphate, and TPP represents triphenyl phosphate. The retardation adjusting agent will be described later.

[Film formation of cellulose acylate film]
(Dissolution)
Cellulose acylate described in Table 3 and additives, Table 3 and Table 4, additives, retardation modifier 1 (RP1), and retardation modifier 2 (RP2) in dichloromethane / methanol (87/13 mass) Part) was stirred and dissolved by stirring to prepare dopes D-1 to D-7. The dopes were prepared so that the viscosity was in the range of 50 to 70 Pa · s. At this time, the dope D-7 has 0.13 parts by mass of a matting agent (AEROSIL R972, manufactured by Nippon Aerosil Co., Ltd., secondary average particle size of 1.0 μm or less) which is fine particles with respect to 100 parts by mass of cellulose acylate. The matting agent dispersion was mixed and stirred as described above. The addition amount of the additive of Table 3 is a mass part of the additive with respect to 100 mass parts of cellulose acylate. Moreover, P-1, P-3, and P-6 described in Table 4 represent the compounds described in Table 1, respectively.

(Casting and stretching)
The above-mentioned dope was co-cast using the band casting machine in the combinations shown in Table 5. The film peeled off from the band in the range of the residual solvent amount of 25 to 40% by mass was stretched in the width direction using a tenter at a stretching temperature of 150 ° C. and a stretching ratio shown in Table 5, and then relaxed. Cellulose acylate films F-1 to F-7 were formed. Here, the draw ratio indicates the maximum draw ratio in the tenter. The maximum draw ratio was based on the casting width. The width and film thickness of the obtained film are shown in Table 5.

  The prepared cellulose acylate film was conditioned for 2 hours or more at 25 ° C. and 60% relative humidity, and was measured at 25 ° C. and 60% relative humidity using a birefringence measuring device (KOBRA 21ADH, manufactured by Oji Scientific Instruments). The Re value and the Rth value at a wavelength of 590 nm were measured, and the results are shown in Table 5.

  The prepared cellulose acylate film is conditioned at 25 ° C. and 60% relative humidity for 2 hours or more, and using a haze meter (HGM-2DP, Suga Test Machine), the haze is measured according to JIS K-6714. Table 5 shows.

  From Table 5, it was found that Re and Rth were suitably expressed in the films F-1 to F-7 having a three-layer structure before the saponification treatment.

[Example 1]: Saponification of cellulose acylate film (Preparation of alkali saponification solution)
Alkalis of the types and amounts shown in Table 6 were gradually dissolved in water to prepare an alkali saponification solution. Table 6 shows the alkali normality of the adjusted alkali saponification solution.

  The cellulose acylate films F-1 to F-7 prepared earlier were immersed in an alkaline saponification solution under the conditions shown in Table 7, and then washed in a room temperature water bath. Then, it neutralized by immersing the cellulose acylate film after washing using 0.1N sulfuric acid at 30 ° C. After washing again in a water bath at room temperature, drying was performed with hot air at 100 ° C. to obtain saponified films S-1 to S-32.

The surface state of the obtained saponified cellulose acylate film was judged according to the following criteria.
◎ Excellent flatness and transparency with no wrinkles or slippage.
○ Slight deflection remains at the edge of the film after saponification, but the film is excellent in transparency.
Δ: Deflection occurred from the edge of the film after saponification, but there is no problem in the polarizing plate processing process, and the film is excellent in transparency.
X Although the film is excellent in transparency, crease remains in the film and is unsuitable for bonding in a polarizing plate processing process.
Xx Not only residual wrinkles but irregularities are formed on the film, and the film is whitened.
The results obtained are listed in Table 7.

  The contact angle with respect to water of the surface that was in contact with the casting support during the production of the saponified cellulose acylate film was measured. The contact angle was measured using an automatic contact angle meter (DM500, Kyowa Interface Chemical Co., Ltd.), and the obtained results are shown in Table 7.

  The obtained saponified cellulose acylate film was conditioned at 25 ° C. and a relative humidity of 60% for 2 hours or more, and the haze was measured according to JIS K-6714 using a haze meter (HGM-2DP, Suga Tester). The results are shown in Table 7.

  The XPS of the surface that was in contact with the casting support during the production of the saponified cellulose acylate film was measured. The XPS was measured by X-ray photoelectric spectroscopy (ESCA) using a photoelectron spectrometer (ESCA3400, manufactured by Shimadzu Corporation) on the surface. In the carbon (C1s) spectrum at that time, the ratio of the maximum peak near 288 eV to the peak of 290 eV was defined as the XPS ratio. The results obtained are listed in Table 7.

[Example 2]: Production of polarizing plate (Production of polarizing plate)
A polyvinyl alcohol (PVA) film having a thickness of 75 μm and a polymerization degree of 2400 was swollen with warm water at 30 ° C. for 40 seconds, and then immersed in an aqueous solution having an iodine concentration of 0.06% by mass and potassium iodide of 6% by mass at 30 ° C. for 60 seconds. Then, while immersed in an aqueous solution having a boric acid concentration of 4% by mass and potassium iodide of 3% by mass at 40 ° C. for 60 seconds, the longitudinal direction becomes 5.0 times the original length. Stretched. Then, it was made to dry at 50 degreeC for 4 minute (s), and the polarizer was obtained.

TD80U manufactured by FUJIFILM Corporation was immersed in an aqueous sodium hydroxide solution at 55 ° C. at 1.5 mol / liter, and then the sodium hydroxide was sufficiently washed away with water. Then, after dipping for 15 seconds in a 35 mol C dilute sulfuric acid aqueous solution at 0.05 mol / liter, the dilute sulfuric acid aqueous solution was sufficiently washed away by dipping in water. Finally, the sample was thoroughly dried at 120 ° C.
The saponified cellulose acylate film S-2 saponified in Example 1 and TD80U manufactured by FUJIFILM Corporation were bonded using a polyvinyl alcohol adhesive so as to sandwich the polarizer, and further heated at 70 ° C. for 30 minutes. did. Then, the edge was cut with a cutter 3 cm from the width direction, and a roll-shaped polarizing plate P-1 having an effective width of 1200 mm and a length of 50 m was produced. At this time, since the polarizer and the protective films on both sides of the polarizer are produced in a roll form, the longitudinal directions of the roll films are parallel to each other and are continuously bonded. Moreover, in the protective film arrange | positioned at the cell side, the transmission axis of a polarizer and the slow axis of each cellulose acylate film are parallel.

  Polarizing plates P-2 to P-5 were similarly produced except that S-10, S-11, S-23, and S-27 were used instead of the saponified cellulose acylate film S-2.

[Coating of adhesive layer]
(Preparation of acrylic polymer solution)
n-butyl acrylate (n-BA) 75 parts by mass, methyl acrylate (MA) 20 parts by mass, 2-hydroxy acrylate (2-HEA) 5 parts by mass, ethyl acetate 100 parts by mass and azobisisobutyronitrile (AIBN) After 0.2 part by mass was put into a reaction vessel and the air in the reaction vessel was replaced with nitrogen gas, the reaction vessel was heated to 60 ° C. in a nitrogen atmosphere with stirring and reacted for 4 hours. After 4 hours, 100 parts by mass of toluene, 5 parts by mass of α-methylstyrene dimer and 2 parts by mass of AIBN were added, the temperature was raised to 90 ° C., and the mixture was further reacted for 4 hours. After the reaction, it was diluted with ethyl acetate to obtain an acrylic polymer solution having a solid content of 20% by mass. To 100 parts by mass of the solid content of the polymer solution, 1.0 part by mass of an isocyanate-based crosslinking agent (trade name: Coronate L, manufactured by Nippon Polyurethane Co., Ltd.) was added and stirred well to obtain an adhesive composition.

(Preparation of pressure-sensitive adhesive polarizing plates 1 to 5)
The pressure-sensitive adhesive was applied to the polarizing plates P-1 to P-5 prepared above.
A 25 μm pressure-sensitive adhesive layer is formed on a film obtained by removing the pressure-sensitive adhesive composition containing the acrylic polymer solution, and transferred to a polarizing plate (on the cell-side protective film). The temperature is 23 ° C. and the humidity is 65%. It was made to age | cure | ripen on conditions for 7 days, and the polarizing plates 1-5 with an adhesive were produced. Further, a separate film was pasted on the adhesive layer. A protective film was affixed on the protective film opposite to the cell.

[Polarizing plate durability]
Before and after aging 1000 hours at 60 ° C. and 90% RH, two sets of the above-prepared polarizing plates 1 to 5 with pressure-sensitive adhesive attached to a glass plate were prepared. The orthogonal transmittance was measured and the degree of polarization was calculated. Durability was evaluated according to the following criteria.

◎ Polarization degree change amount 0% or less, greater than -0.3%.
○ Polarization degree change amount −0.3% or less, greater than −0.5%.
Δ Polarization degree change amount: −0.5% or less, greater than −1.0%.
X Polarization degree change -1.0% or less.
The obtained results are shown in Table 8.

  From Table 8, it is clear that in the polarizing plate using the film of the present invention, the change in the degree of polarization with respect to heat and humidity is small and the durability is excellent. In addition, it was found that the polarizing plates 1 to 5 were unable to peel off the saponified film by hand even after 2 hours at 60 ° C. and 90% relative humidity, and no shrinkage occurred. .

[Example 3]: Mounting on a liquid crystal display device (mounting on a VA panel)
VA mode liquid crystal TV (LC-20C5, manufactured by Sharp Corporation) The front and back polarizing plates and the phase difference plate were peeled off, and the polarizing plates 1 to 5 and the viewing angles prepared and adjusted in Example 2 on the front and back sides. A commercially available polarizing plate without a compensation plate (HLC2-5618, manufactured by Sanlitz Co., Ltd.) was attached in a combination shown in Table 9 using a laminator roll.
In this case, the absorption axis of the polarizing plate on the viewing side is in the horizontal direction of the panel, the absorption axis of the polarizing plate on the backlight side is in the vertical direction of the panel, and the pressure-sensitive adhesive surface is on the liquid crystal cell side.

(Viewing angle durability)
Using a measuring instrument (EZ-Contrast 160D, manufactured by ELDIM), the viewing angle (range with a contrast ratio of 10 or more and no black-side gradation inversion) in 8 stages from black display (L1) to white display (L8) ) Was measured. The liquid crystal display device using the polarizing plate of the present invention showed a good viewing angle of 80 degrees or more on both the left and right sides at 25 ° C. and a relative humidity of 60%. Thereafter, the liquid crystal display device is allowed to stand for 24 hours under conditions of 60 ° C. and 90% relative humidity, and then conditioned for 2 hours or more at 25 ° C. and 60% relative humidity, and again at 25 ° C. and 60% relative humidity. When the angle was measured, the right viewing angle of 80 degrees or more on both the left and right sides was rated as “◯”, and the other cases were marked as “X”.

  From the results of Table 8 and Table 9, it was found that the polarizing plate using the film of the present invention is a polarizing plate having a small change in the degree of polarization with respect to heat and humidity, excellent durability, and excellent display performance. .

Claims (25)

It is saponified under the conditions represented by the following formulas (A-1) to (A-3), contains cellulose acylate satisfying the following formula (B), and has a water contact angle of 30 on at least one surface. A cellulose acylate film having a temperature of less than 0 ° and a film thickness of 60 μm or less .
Formula (A-1): 25 ≦ T ≦ 45
(In the formula (A-1), T represents a saponification temperature (unit: ° C.).)
Formula (A-2): 0.5 ≦ S ≦ 5
(In the formula (A-2), S represents the saponification time (unit: minutes).)
Formula (A-3): 0.5 ≦ D ≦ 4.5
(In formula (A-3), D represents the alkali normality (unit: N) of the saponification solution.)
Formula (B): 2.0 ≦ DS ≦ 2.7
(In the formula (B), DS represents the acyl group substitution degree of the hydroxyl group of the glucose unit in cellulose.)   The cellulose acylate film according to claim 1, which has a laminate structure of two or more. At least one layer contains cellulose acylate satisfying the following formula (B),
The cellulose acylate according to claim 2, wherein at least one layer different from the layer containing the cellulose acylate satisfying the following formula (B) contains the cellulose acylate satisfying the following formula (C). Rate film.
Formula (B): 2.0 ≦ DS ≦ 2.7
Formula (C): 2.7 ≦ DS ≦ 3.0
(In formulas (B) and (C), DS represents the acyl group substitution degree of the hydroxyl group of the glucose unit in cellulose.) It has a laminated structure of 3 or more,
At least one inner layer contains cellulose acylate satisfying the following formula (B),
The cellulose acylate film according to claim 2 or 3, wherein the surface layers on both sides contain cellulose acylate satisfying the following formula (C).
Formula (B): 2.0 ≦ DS ≦ 2.7
Formula (C): 2.7 ≦ DS ≦ 3.0
(In formulas (B) and (C), DS represents the acyl group substitution degree of the hydroxyl group of the glucose unit in cellulose.)   The film thickness of at least 1 surface layer is 0.5-5 micrometers, The cellulose acylate film as described in any one of Claims 2-4 characterized by the above-mentioned.   The cellulose acylate film according to any one of claims 1 to 5, wherein the cellulose acylate film is formed by co-casting.   The cellulose acylate according to any one of claims 1 to 6, wherein the saponification treatment includes a saponification step using an alkaline saponification solution that causes a saponification reaction to proceed, and a step of slowing or stopping the saponification reaction. the film.   The cellulose acylate film according to claim 7, wherein the step of slowing or stopping the saponification reaction is a dilution step or a neutralization step.   The ratio of a peak at 290 eV to a maximum peak near 288 eV in a carbon (C1s) spectrum when measuring at least one surface by X-ray photoelectron spectroscopy is 0.50 or less. The optical cellulose acylate film according to any one of the above. The cellulose acylate film according to any one of claims 1 to 9 , wherein a haze is 1.0% or less. The thickness-direction retardation Rth (590) in-plane retardation value Re (590) and wavelength 590nm at a wavelength of 590nm, according to claim 1-10, characterized by satisfying the following formulas (I) and (II) The cellulose acylate film according to any one of the above.
Formula (I): 30 nm ≦ Re (590) ≦ 70 nm
Formula (II): 80 nm ≦ Rth (590) ≦ 250 nm A cellulose acylate satisfying the following formula (B) is contained, and a cellulose acylate film having a film thickness of 60 μm or less is saponified under conditions satisfying the following formulas (A-1) to (A-3). A method for saponifying a cellulose acylate film.
Formula (A-1): 25 ≦ T ≦ 45
(In the formula (A-1), T represents a saponification temperature (unit: ° C.).)
Formula (A-2): 0.5 ≦ S ≦ 5
(In the formula (A-2), S represents the saponification time (unit: minutes).)
Formula (A-3): 0.5 ≦ D ≦ 4.5
(In formula (A-3), D represents the alkali normality (unit: N) of the saponification solution.)
Formula (B): 2.0 ≦ DS ≦ 2.7
(In the formula (B), DS represents the acyl group substitution degree of the hydroxyl group of the glucose unit in cellulose.) A cellulose acylate satisfying the following formula (B) is contained, and a cellulose acylate film having a film thickness of 60 μm or less is saponified under conditions satisfying the following formulas (A-1) to (A-3). A method for producing a cellulose acylate film.
Formula (A-1): 25 ≦ T ≦ 45
(In the formula (A-1), T represents a saponification temperature (unit: ° C.).)
Formula (A-2): 0.5 ≦ S ≦ 5
(In the formula (A-2), S represents the saponification time (unit: minutes).)
Formula (A-3): 0.5 ≦ D ≦ 4.5
(In formula (A-3), D represents the alkali normality (unit: N) of the saponification solution.)
Formula (B): 2.0 ≦ DS ≦ 2.7
(In the formula (B), DS represents the acyl group substitution degree of the hydroxyl group of the glucose unit in cellulose.)   The method for producing a cellulose acylate film according to claim 13, wherein the cellulose acylate film before the saponification treatment has a laminated structure of two or more. At least one layer of the cellulose acylate film before the saponification treatment contains cellulose acylate satisfying the following formula (B),
The cellulose acylate according to claim 14, wherein at least one layer different from the layer containing the cellulose acylate satisfying the following formula (B) contains the cellulose acylate satisfying the following formula (C). A method for producing a rate film.
Formula (B): 2.0 ≦ DS ≦ 2.7
Formula (C): 2.7 ≦ DS ≦ 3.0
(In formulas (B) and (C), DS represents the acyl group substitution degree of the hydroxyl group of the glucose unit in cellulose.) The cellulose acylate film before the saponification treatment has a laminate structure of 3 or more,
At least one inner layer contains cellulose acylate satisfying the following formula (B),
The method for producing a cellulose acylate film according to claim 14 or 15, wherein the surface layers on both sides contain cellulose acylate satisfying the following formula (C).
Formula (B): 2.0 ≦ DS ≦ 2.7
Formula (C): 2.7 ≦ DS ≦ 3.0
(In formulas (B) and (C), DS represents the acyl group substitution degree of the hydroxyl group of the glucose unit in cellulose.)   The cellulose acylate film according to any one of claims 14 to 16, wherein a film thickness of at least one surface layer of the cellulose acylate film before the saponification treatment is 0.5 to 5 µm. Method.   The method for producing a cellulose acylate film according to any one of claims 13 to 17, wherein the cellulose acylate film before the saponification treatment is formed by co-casting.   The cellulose acylate according to any one of claims 13 to 18, wherein the saponification treatment includes a saponification step using an alkaline saponification solution that causes the saponification reaction to proceed, and a step of slowing or stopping the saponification reaction. A method for producing a film.   The method for producing a cellulose acylate film according to claim 19, wherein the step of slowing or stopping the saponification reaction is a dilution step or a neutralization step. The conditions are selected within a range satisfying the formulas (A-1) to (A-3) so that the contact angle of water on at least one surface is less than 30 °. The manufacturing method of the cellulose acylate film as described in any one of Claims. A cellulose acylate film produced by the method for producing a cellulose acylate film according to any one of claims 13 to 21 . In the polarizing plate in which a protective film is bonded to both sides of a polarizer, at least one of the protective films is the cellulose acylate film according to any one of claims 1 to 12 and 22. Polarizer. A liquid crystal display device comprising the polarizing plate according to claim 23 . The liquid crystal display device according to claim 24 , wherein the liquid crystal display device is in a VA mode.