JP2013061563A - Retardation film and manufacturing method of the same, and polarizing plate, liquid crystal display device and organic electroluminescent (el) display device using the film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a retardation film and a manufacturing method of the film, which has high transmitting property, can maintain retardation developing property required for a display device even when the film is made thin, and can maintain stable qualities.SOLUTION: In the retardation film containing cellulose acylate, the cellulose acylate used has such characteristics that: an acyl group substitution degree ranges from 1.9 to 2.5; a half value width of a peak in a composition distribution of the acyl group substitution degree measured by HPLC (high performance liquid chromatography) is 0.15 or less in a substitution degree unit; and a percentage of cellulose acylate included in the half value width in the composition distribution is 65% or more. The cellulose acylate is obtained by reacting cellulose with an acylation agent in the presence of an ionic liquid.

Description

  The present invention relates to a retardation film and a method for producing the same, and a polarizing plate, a liquid crystal display device and an organic EL display device using the same.

  Among cellulose esters, it is known that cellulose acylate can be applied to optical films having a wide range of retardation by changing the acyl group substitution degree. Generally, triacetyl cellulose (TAC) having a high degree of acetyl group substitution is suitably used for a protective film for polarizing plates because of its low retardation. On the other hand, in order to use triacetyl cellulose as an optical compensation film in various liquid crystal modes such as VA type and TN type, since the expression of retardation is insufficient, it is necessary to add a retardation adjusting agent.

  On the other hand, diacetyl cellulose (DAC) having a low degree of acetyl group substitution has high retardation, so that it can function as an optical compensation film (viewing angle expanding film) without adding a retardation adjusting agent. It is expected to be able to demonstrate. Here, in order to manufacture a display device with higher display quality, an optical film excellent in properties such as transparency, thin film, and retardation development is required.

  As described above, the retardation film using DAC has high birefringence (retardation) compared to TAC, but it is necessary to further increase the draw ratio in order to further reduce the film thickness, which makes manufacturing difficult. There were problems in the production of highly stable films.

  Diacetyl cellulose is usually adjusted in substitution degree by carrying out hydrolysis after acyl substitution of all OH groups. In this method, the substitution degree distribution tends to widen by hydrolysis. In addition, when manufacturing a retardation film, this minute variation in the degree of substitution adversely affects the retardation development. Therefore, in order to stably manufacture a thin film and a highly transmissive optical film, a cellulose acyl having a high purity is used. The rate was sought.

  By the way, Patent Document 1 discloses a method for producing a cellulose mixed ester characterized by adding two or more esterifying agents to a mixture composed of cellulose and an ionic liquid. Moreover, although there exists disclosure about film fields, such as a polarizing plate protective film and an optical film, as a use of the cellulose mixed ester obtained by this manufacturing method, the use as a retardation film is not disclosed.

JP 2011-74113 A

  The present invention has been made in view of the above-described conventional technology, has high transparency, can maintain the phase difference required for a display device even when thinned, and can maintain stable quality. An object of the present invention is to provide a retardation film and a method for producing the same.

  The present inventor has conducted extensive research in view of the above-described object. As a result, when a cellulose acylate film is formed using cellulose acylate having a small acyl group substitution degree (such as DAC), the above problem is solved by using a film having a sharp peak in the composition distribution of the acyl group substitution degree. Found that could be resolved. In addition, by acylating cellulose in the presence of an ionic liquid, cellulose acylate having a sharp peak in the degree of acyl group substitution as described above can be obtained without using the conventional method of hydrolysis after total acyl substitution. It has also been found that it can be manufactured. And based on these knowledge, it came to complete this invention.

  That is, the above object of the present invention is achieved by the following configuration.

(1) A retardation film comprising a cellulose ester,
The acyl substitution degree of the cellulose acylate is 1.9 to 2.5, the half width of the peak in the composition distribution measured by HPLC of the acyl substitution degree is 0.15 or less in substitution degree units, A retardation film in which the ratio of cellulose acylate contained in the half-value width in the composition distribution is 65% or more;
(2) The following general formula (I):

In the formula, Q represents a monosaccharide or disaccharide residue, R represents an aliphatic group or an aromatic group, and m represents the number of hydroxyl groups directly bonded to the monosaccharide or disaccharide residue. L is the sum of the number of — (O—C (═O) —R) groups directly attached to the monosaccharide or disaccharide residue, and 3 ≦ m + l ≦ 8, l ≠ 0,
Retardation film as described in said (1) containing the sugar ester compound represented by these;
(3) The following formula (1) and the following formula (2):

In the formula, nx represents the refractive index in the slow axis direction in the film plane, ny represents the refractive index in the fast axis direction in the film plane, nz represents the refractive index in the film thickness direction, and d represents the film thickness. Represents thickness (nm); refractive index measured at a wavelength of 590 nm in an environment of 25 ° C. and 55% RH)
And Ro and Rth respectively represented by

The retardation film according to (1) or (2), which satisfies
(4) Formula (1) below:

(In the formula, nx represents the refractive index in the slow axis direction in the film plane, ny represents the refractive index in the fast axis direction in the film plane, nz represents the refractive index in the film thickness direction, and d represents the film. The refractive index is measured at a wavelength of 590 nm in an environment of 25 ° C. and 55% RH)
Ro represented by

The retardation film according to (1) or (2), which satisfies
(5) reacting cellulose with an acylating agent in the presence of an ionic liquid to obtain a cellulose acylate having an acyl group substitution degree of 1.9 to 2.5;
The film obtained by pouring the dope containing the cellulose acylate onto a support is dried and peeled, and then stretched at least in the width direction at a stretch ratio of 1.1 times or more to obtain a film width of 1.8 to 2. Obtaining a 5 m retardation film;
A method for producing a retardation film, comprising:
(6) reacting cellulose with an acylating agent in the presence of an ionic liquid to obtain a cellulose acylate having an acyl group substitution degree of 1.9 to 2.5;
Drying the film obtained by pouring the dope containing the cellulose acylate on a support, peeling, and then performing oblique stretching to obtain a retardation film; and
A method for producing a retardation film, comprising:
(7) The retardation film according to any one of (1) to (4) above or the retardation film produced by the production method according to (5) or (6) above, and at least one of the polarizers A polarizing plate, which is bonded to the surface of
(8) The retardation film according to any one of (1) to (3) or the retardation film produced by the production method according to (5), and at least one surface of a polarizer. A liquid crystal display device provided with a polarizing plate bonded;
(9) The retardation film described in (1), (2) or (4) above or the retardation film manufactured by the manufacturing method described in (6) above and at least one surface of the polarizer are attached. An organic EL display device provided with a polarizing plate formed by combining.

  According to the present invention, there are provided a retardation film having high transparency, capable of maintaining the retardation development necessary for a display device even when it is thinned, and capable of maintaining stable quality, and a method for producing the same. sell.

In an Example, it is explanatory drawing of the extending | stretching apparatus used in manufacturing a phase difference film by the diagonal stretch process.

  Hereinafter, embodiments of the present invention will be described in detail.

≪Phase difference film≫
One form of the present invention provides a retardation film containing cellulose acylate. And the acyl group substitution degree of the cellulose acylate which comprises this retardation film is 1.9-2.5, and the half value width of the peak in the composition distribution measured by HPLC of the said acyl group substitution degree is a substitution degree unit. It is 0.15 or less, and the ratio of the cellulose acylate contained in the half width in the composition distribution is characterized by being 65% or more.

<Cellulose acylate>
The cellulose acylate film according to one embodiment of the present invention includes a cellulose acylate having an acyl group substitution degree of 1.9 to 2.5. By adopting cellulose acylate with a low degree of acyl group substitution in this way, high retardation development is exhibited, and even when it is a retardation film with high retardation, it is possible to reduce the thickness. Even when the phase difference is developed, advantages such as the fact that the draw ratio can be kept low and failures such as fracture can be avoided.

  Here, the cellulose molecule consists of many glucose units connected, and the glucose unit has three hydroxyl groups. The number of acyl groups derived from these three hydroxyl groups is called the degree of substitution. For example, diacetylcellulose (DAC) has an acetyl group bonded to an average of 1.9 to 2.5 of the three hydroxyl groups of the glucose unit.

  Examples of the cellulose acylate used in the present invention include carboxylic acid esters having about 2 to 22 carbon atoms, which may be esters of aromatic carboxylic acids, but are particularly preferably lower fatty acid esters of cellulose. The lower fatty acid in the lower fatty acid ester of cellulose means a fatty acid having 6 or less carbon atoms. The acyl group bonded to the hydroxyl group may be linear or branched or may form a ring. Furthermore, another substituent may be substituted. When the degree of substitution is the same, birefringence decreases when the number of carbon atoms in the acyl group is large. Therefore, the number of carbon atoms is preferably selected from acyl groups having 2 to 6 carbon atoms. The acyl group preferably has 2 to 4 carbon atoms, more preferably 2 to 3 carbon atoms.

  For example, cellulose acetate, cellulose propionate, cellulose butyrate and the like, cellulose acetate propio as described in JP-A Nos. 10-45804, 8-231761, US Pat. No. 2,319,052, etc. It is preferable to use mixed fatty acid esters such as nate, cellulose acetate butyrate, and cellulose acetate phthalate.

  In addition, the measurement of the acyl group substitution degree of a cellulose acylate can be implemented according to ASTM-D817-96, and a preferable acyl group substitution degree is 2.18-2.45.

  When the acyl group substitution degree of cellulose acylate is less than 1.9, deterioration of film surface quality due to increase in dope viscosity, haze-up due to increase in stretching tension, and the like may occur. Further, when the acyl group substitution degree is larger than 2.5, it is difficult to obtain a necessary phase difference.

  The number average molecular weight (Mn) of the cellulose acylate is preferable because the mechanical strength of the film from which a range of 30000 to 300000 is obtained is strong. Furthermore, the thing of 50000-200000 is used preferably.

  The ratio (Mw / Mn) of the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the cellulose acylate is preferably 1.4 to 3.0.

  In addition, the value measured using a gel permeation chromatography (GPC) shall be employ | adopted as a value of the number average molecular weight (Mn) and weight average molecular weight (Mw) of a cellulose acylate. At this time, the measurement conditions are as follows.

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

  The present invention is characterized in that the cellulose acylate constituting the retardation film has a sharp peak in the composition distribution of the acyl substitution degree described above. Specifically, the half width of the peak in the composition distribution measured by HPLC of the acyl group substitution degree of the cellulose acylate constituting the retardation film is 0.15 or less, preferably 0.14 or less in substitution degree units. Yes, more preferably 0.13 or less, and most preferably 0.12 or less. Moreover, the ratio of the cellulose acylate contained in the half width in the composition distribution is 65% or more, preferably 70% or more, more preferably 75% or more, and most preferably 80% or more. The fact that the above parameters in the cellulose acylate constituting the retardation film are out of these ranges means that the substitution degree distribution is broad. When a retardation film is produced using such cellulose acylate, variations in the substitution degree distribution adversely affect the retardation development, and a thinner and highly transparent optical film can be produced stably. It becomes difficult. In addition, as the values of these parameters, values measured by the measurement method described in the column of Examples described later are adopted.

  The method for synthesizing the cellulose acylate used in the present invention is not particularly limited, but according to the study by the present inventors, the conventional method of adjusting the degree of substitution by carrying out hydrolysis after acyl substitution of all OH groups of cellulose. However, it was found that by performing the acylation reaction of cellulose in a homogeneous system using an ionic liquid as a solvent, a peak having a sharp peak in the composition distribution of the degree of acyl group substitution can be obtained. That is, the cellulose acylate having an acyl group substitution degree of 1.9 to 2.5 used in the present invention reacts with an acylating agent (hereinafter also simply referred to as “acylation”) in the presence of an ionic liquid. It is preferable that it is obtained.

  There is no restriction | limiting in particular about the specific form of acylation, Those skilled in the art can set suitably, referring a conventionally well-known knowledge. Hereinafter, although the preferable form of acylation is demonstrated, it is not necessarily limited only to these forms.

  Cellulose used as a raw material originates from plants such as wood, cotton, hemp, flax, ramie, jute, kenaf, animal origin such as sea squirts, algae such as seaweed, microorganisms such as acetic acid bacteria, etc. It may be. Among these, refined pulp, regenerated cellulose, cotton-derived cotton linter and cotton lint, and bacterial cellulose derived from acetic acid bacteria can be suitably employed because of their high cellulose purity. The α cellulose content, which is an indicator of cellulose purity, is preferably 90% by weight or more. If the α cellulose content is 90% by weight or more, side reactions in the esterification of cellulose can be suppressed, and the color tone of the resulting cellulose mixed ester is preferable. The α cellulose content is more preferably 92% by weight or more, and still more preferably 95% by weight or more.

  Cellulose is not particularly limited with respect to form, and may be any of powder, granule, cotton, thread, cloth, paper, sheet, film and the like. Moreover, you may use the cellulose which gave processes, such as a grinding | pulverization process. Examples of the pulverization method include a dry pulverizer such as a ball mill. It is preferable that the surface area of cellulose is increased by pulverization because it is easily dissolved in an ionic liquid.

  Acylation is carried out in the presence of an ionic liquid. Cellulose does not dissolve in ordinary organic solvents, but can dissolve in ionic liquids. Therefore, acylation can be performed in a homogeneous system by performing acylation in the presence of an ionic liquid.

  An ionic liquid will not be specifically limited if it is a compound which consists of a cation and an anion and can dissolve a cellulose uniformly. Moreover, an ionic liquid may be used independently and multiple may be used together.

  Examples of the cation constituting the ionic liquid include imidazole, pyridine, ammonia, pyrroline, pyrazole, carbazole, indole, lutidine, pyrrole, pyrazole, piperidine, pyrrolidine, 1,8-diazabicyclo [5.4.0] undec-7-ene. , 1,5-diazabicyclo [4.3.0] -5-nonene, and the like, but are not limited to compounds in which a proton or an alkyl group is bonded to the nitrogen atom. Among them, an imidazolium cation or a pyridinium cation having imidazole or pyridine in the skeleton can be preferably employed because of excellent solubility of cellulose.

  Specific examples of the cation include 1,3-dimethylimidazolium, 1-ethyl-3-methylimidazolium, 1-butyl-3-methylimidazolium, 1-hexyl-3-methylimidazolium, and 1-octyl-3. -Methylimidazolium, 1-decyl-3-methylimidazolium, 1-tetradecyl-3-methylimidazolium, 1-hexadecyl-3-methylimidazolium, 1-octadecyl-3-methylimidazolium, 1-ethyl-2 , 3-dimethylimidazolium, 1-butyl-2,3-dimethylimidazolium, 1-hexyl-2,3-dimethylimidazolium, 1-ethylpyridinium, 1-butylpyridinium, 1-hexylpyridinium, 1-butyl- 4-methylpyridinium, 1-butyl-3-methylpyridinium, 1 Hexyl-4-methylpyridinium, 1-hexyl-3-methylpyridinium, 4-methyl-octylpyridinium, 3-methyl-octylpyridinium, 3,4-dimethyl-butylpyridinium, 3,5-dimethyl-butylpyridinium, trimethylpropyl Examples include, but are not limited to, ammonium, methylpropylpiperidinium, and the like.

  Examples of the anion constituting the ionic liquid include, but are not limited to, a halogen anion, a pseudohalogen anion, a carboxylate anion, a superacid anion, a sulfonate anion, and a phosphate anion. Among these, a halogen anion, a carboxylic acid anion, and a phosphate anion can be preferably used because they are excellent in solubility of cellulose.

  Examples of the halogen anion include a fluorine anion, a chlorine anion, a bromine anion, and an iodine anion.

  Examples of the pseudohalogen anion include cyan anion, thiocyanate anion, cyanate anion, fullinate anion, azide anion and the like.

  Examples of the carboxylic acid anion include a monocarboxylic acid anion having 1 to 18 carbon atoms or a dicarboxylic acid anion. Specific examples include formate anion, acetate anion, fumarate anion, oxalate anion, lactate anion, pyruvate anion and the like.

  Examples of the super strong acid anion include a borofluoric acid anion, a tetrafluoroboric acid anion, a perchloric acid anion, a hexafluorophosphoric acid anion, a hexafluoroantimonic acid anion, and a hexafluoroarsenic acid anion.

  Examples of the sulfonate anion include sulfonic acids having 1 to 26 carbon atoms. Specific examples include methanesulfonate anion, p-toluenesulfonate anion, octylbenzenesulfonate anion, dodecylbenzenesulfonate anion, laurylbenzenesulfonate anion, octadecylbenzenesulfonate anion, eicosylbenzenesulfonate anion, octanesulfone. An acid anion, a dodecane sulfonic acid anion, an eicosane sulfonic acid anion, etc. are mentioned.

  Examples of the phosphate anion include a phosphate anion and a phosphate ester anion having 1 to 40 carbon atoms. Specific examples include phosphate anion, methyl phosphate monoester anion, octyl phosphate monoester anion, octyl phosphate diester anion, lauryl phosphate monoester anion, lauryl phosphate diester anion, stearyl phosphate monoester anion, stearyl phosphate An acid diester anion, an eicosyl phosphate monoester anion, an eicosyl phosphate diester anion, and the like.

  Various ionic liquids can be produced by combining these cations and anions. Specific examples of ionic liquids include 1,3-dimethylimidazolium methyl sulfate, 1-ethyl-3-methyl-imidazolium chloride, 1-ethyl-3-methyl-imidazolium bromide, 1-ethyl-3-methylimidazolium. Methanesulfonate, 1-butyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium acetate, 1-hexyl-3-methylimidazolium hexafluorophosphate, 1-octyl-3-methylimidazolium tetrafluoroborate 1-decyl-3-methylimidazolium chloride, 1-tetradecyl-3-methylimidazolium chloride, 1-ethyl-2,3-dimethylimidazolium chloride, 1-butyl-2,3-dimethylimidazolium trifluoro Tan sulfonate, 1-hexyl-2,3-dimethylimidazolium chloride, 1-ethylpyridinium bromide, 1-butylpyridinium bromide, 1-butylpyridinium hexafluorophosphate, 1-hexylpyridinium hexafluorophosphate, 1-butyl-4 -Methylpyridinium tetrafluoroborate, 3,5-dimethylbutylpyridinium chloride, 1-butyl-3-methylimidazolium tetrachloroaluminate, 1-butyl-3-methylimidazolium hexafluorophosphate, 1-ethyl-3-methyl Imidazolium trifluoromethanesulfonate, 1-butylpyridinium nitrate, dimethylmethyl-2-methoxyethylammonium tetrafluoroborate, dimethylmethyl 2-methoxyethyl ammonium bistrifluoromethanesulfonylimide, trimethylpropylammonium bistrifluoromethanesulfonylimide, but like methylpropyl piperidinium bistrifluoromethanesulfonylimide, without limitation.

  Although there is no restriction | limiting in particular regarding melting | fusing point of an ionic liquid, It is preferable that it is 100 degrees C or less. If the melting point of the ionic liquid is 100 ° C. or lower, it is preferable because the molecular weight reduction of the cellulose can be suppressed when the cellulose is dissolved in the ionic liquid. The melting point of the ionic liquid is more preferably 80 ° C. or less, and further preferably 70 ° C. or less.

  The acylation is performed by reacting cellulose with an acylating agent using the above-described ionic liquid as a solvent.

  Examples of the acylating agent include acid halides, acid anhydrides, carboxylic acids and the like. Only one acylating agent may be used alone, or two or more acylating agents may be used in combination.

  Examples of the acid halide include acid fluoride, acid chloride, acid bromide, and acid iodide. Specific examples include acetyl fluoride, acetyl chloride, acetyl bromide, acetyl iodide, propionyl fluoride, propionyl chloride, propionyl bromide, propionyl iodide, butyryl fluoride, butyryl chloride, butyryl bromide, butyryl iodide, Examples include benzoyl fluoride, benzoyl chloride, benzoyl bromide, and benzoyl iodide. Among these, acid chlorides can be suitably employed from the viewpoints of reactivity and handleability.

  Acid anhydrides include acetic anhydride, propionic anhydride, butyric anhydride, valeric anhydride, caproic anhydride, enanthic anhydride, caprylic anhydride, pelargonic anhydride, capric anhydride, lauric anhydride, myristic anhydride, palmitic anhydride Examples thereof include acid, stearic anhydride, benzoic anhydride, phthalic anhydride, maleic anhydride, and succinic anhydride. Of these, propionic anhydride and butyric anhydride can be suitably employed because of their high reactivity.

  Carboxylic acids include acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, benzoic acid, phthalic acid, maleic acid And succinic acid.

  More specifically, when the acylating agent is an acetylating agent, specific examples of the acetylating agent include acetyl chloride, acetic anhydride, acetic acid and the like. Specific examples of the acylating agent having 3 carbon atoms include propionyl chloride, propionic anhydride, and propionic acid. In the case of using an acylating agent having 4 or less carbon atoms, it is preferable to use an acid anhydride, and in the case of using an acylating agent having 5 or more carbon atoms, it is preferable to use an acid halide.

  A catalyst may be used to promote the acylation of cellulose. Examples of the catalyst include, but are not limited to, sulfuric acid, hydrochloric acid, hydrobromic acid, perchloric acid, hypochlorous acid, nitric acid, and zinc chloride. Among these, sulfuric acid can be preferably used from the viewpoint of reactivity. These catalysts may be used alone or in combination.

  In the mixture of cellulose and ionic liquid of the present invention, the ionic liquid may be added to cellulose, or cellulose may be added to the ionic liquid. Further, when the ionic liquid is solid at room temperature, it may be mixed with cellulose as it is, or may be mixed with cellulose after being once heated and melted.

  The cellulose and ionic liquid used for acylation are preferably set in advance to a low moisture content by vacuum drying or heat drying, and each moisture content is preferably 3% by weight or less. A moisture content of 3% by weight or less is preferable because it can suppress molecular weight reduction due to hydrolysis of cellulose and consumption of the acylating agent due to hydrolysis of the acylating agent. The moisture content is more preferably 2% by weight or less, and further preferably 1% by weight or less.

  The cellulose weight relative to the weight of the ionic liquid can be selected as appropriate because the solubility of cellulose varies depending on the type of ionic liquid, but is preferably 1 to 40% by weight. If the weight of the cellulose with respect to the weight of the ionic liquid is 1% by weight or more, it is preferable because the cellulose can be dissolved uniformly. The weight of cellulose relative to the weight of the ionic liquid is more preferably 3% by weight or more, and further preferably 5% by weight or more. On the other hand, if the weight of the cellulose with respect to the weight of the ionic liquid is 40% by weight or less, it is preferable because the viscosity does not become too high after dissolving the cellulose in the ionic liquid. The weight of cellulose relative to the weight of the ionic liquid is more preferably 30% by weight or less, and further preferably 20% by weight or less.

  The heating temperature of the mixture composed of the ionic liquid and cellulose can be appropriately selected according to the melting point of the ionic liquid, the amount of cellulose added to the ionic liquid, etc., but is preferably 50 to 100 ° C. A heating temperature of 50 ° C. or higher is preferable because dissolution of cellulose can be promoted. The heating temperature is more preferably 60 ° C. or higher, and further preferably 70 ° C. or higher. On the other hand, a heating temperature of 100 ° C. or lower is preferable because it can suppress a decrease in the molecular weight of cellulose. The heating temperature is more preferably 90 ° C. or less, and further preferably 80 ° C. or less.

  The heating time of the mixture composed of the ionic liquid and cellulose can be appropriately selected depending on the heating temperature, the type of the ionic liquid, the amount of cellulose added to the ionic liquid, and the like, but it is 0.5 to 10 hours. preferable. A heating time of 0.5 hour or longer is preferable because cellulose can be dissolved uniformly. The heating time is more preferably 1 hour or longer, and further preferably 2 hours or longer. On the other hand, a heating time of 10 hours or less is preferable because a decrease in molecular weight of cellulose can be suppressed. The heating time is more preferably 8 hours or less, and further preferably 5 hours or less.

  Examples of the heating means for the mixture composed of the ionic liquid and cellulose include, but are not limited to, general heating means such as water bath or oil bath, oven heating, microwave heating, and the like according to known methods.

  In heating the mixture composed of the ionic liquid and cellulose, it is preferable to stir in order to promote dissolution of cellulose. Stirring means include, but are not limited to, mechanical stirring by a stirring bar or stirring blade, stirring by shaking a container, stirring by ultrasonic irradiation, and the like according to a known method.

  If undissolved or insoluble matter remains in the solution obtained by dissolving cellulose in the ionic liquid, remove the undissolved or insoluble matter by filtration and then add the esterifying agent. May be.

  The total number of acylating agents for the glucose unit of cellulose and the total equivalent amount thereof can be appropriately selected according to the acyl group substitution degree of the target cellulose acylate.

  When adding a catalyst in order to accelerate | stimulate esterification reaction, it is preferable that the weight of the catalyst with respect to the weight of a cellulose is 1 to 15 weight%. If the weight of the catalyst with respect to the weight of cellulose is 1% by weight or more, it is preferable because the esterification reaction of cellulose can be promoted. The weight of the catalyst relative to the weight of cellulose is more preferably 3% by weight or more, and further preferably 5% by weight or more. On the other hand, if the weight of the catalyst with respect to the weight of cellulose is 15% by weight or less, a decrease in the molecular weight of cellulose can be suppressed, which is preferable. The weight of the catalyst with respect to the weight of cellulose is more preferably 10% by weight or less, and further preferably 7% by weight or less.

  The reaction temperature for the acylation can be appropriately selected according to the reaction conditions such as the type and addition amount of the acylating agent, the type and addition amount of the catalyst, and is preferably 50 to 100 ° C. A reaction temperature of 50 ° C. or higher is preferable because the esterification reaction of cellulose can be promoted. The reaction temperature is more preferably 60 ° C. or higher, and further preferably 70 ° C. or higher. On the other hand, a reaction temperature of 100 ° C. or lower is preferable because it can suppress a decrease in the molecular weight of cellulose. The reaction temperature is more preferably 90 ° C. or lower, and further preferably 80 ° C. or lower.

  The reaction time between the cellulose and the esterifying agent can be appropriately selected according to the reaction conditions such as the reaction temperature, the type and addition amount of the esterifying agent, the type and addition amount of the catalyst, and 0.5 to 10 hours. It is preferable that A reaction time of 0.5 hour or longer is preferred because the esterification reaction of cellulose proceeds. The reaction time is more preferably 1 hour or longer, and further preferably 2 hours or longer. On the other hand, a reaction time of 10 hours or less is preferable because it can suppress a decrease in the molecular weight of cellulose. The reaction time is more preferably 8 hours or less, and further preferably 5 hours or less.

  Examples of the heating means in the reaction between cellulose and the acylating agent include, but are not limited to, general heating means such as heating with a water bath or oil bath, heating with an oven, and heating with microwaves according to a known method.

  In the reaction between cellulose and an acylating agent, it is preferable to stir to promote the acylation reaction. Stirring means include, but are not limited to, mechanical stirring by a stirring bar or stirring blade, stirring by shaking a container, stirring by ultrasonic irradiation, and the like according to a known method.

The reaction between cellulose and the acylating agent can be stopped by a reaction terminator such as alcohol such as methanol or ethanol, or water. The reaction terminator hydrolyzes an excess amount of the esterifying agent that did not participate in the esterification reaction with cellulose, and insolubilizes and precipitates the cellulose mixed ester. A reaction terminator may be added to the reaction solution, or a reaction solution may be added to the reaction terminator. The precipitated cellulose acylate can be separated by filtration or centrifugation according to a known method. The separated cellulose acylate may be washed once or a plurality of times with an alcohol such as methanol or ethanol, water or the like, and then vacuum-dried or heat-dried as necessary.

<Additives>
The retardation film according to one embodiment of the present invention may contain various additives in addition to the above-described cellulose acylate. Hereinafter, additives that can be used in the present invention will be described.

(Sugar ester compound)
The retardation film according to one embodiment of the present invention preferably contains a sugar ester compound. Thus, since the retardation film contains a sugar ester compound, hydrolysis of the cellulose acylate is prevented, so that the water resistance of the film can be improved. In addition, the film surface is saponified at the time of bonding with a polarizer when constituting a polarizing plate, but hydrolysis of cellulose acylate during the saponification treatment and accompanying elution into an alkaline saponification solution are also possible. Can be prevented.

  As an example of the sugar ester compound, the following general formula (I):

The compound represented by these is mentioned.

  In general formula (I), Q represents a monosaccharide or disaccharide residue, R represents an aliphatic group or an aromatic group, and m is directly bonded to the monosaccharide or disaccharide residue. 1 is the total number of — (O—C (═O) —R) groups directly bonded to the monosaccharide or disaccharide residue, and 3 ≦ m + 1 ≦ 8 and l ≠ 0.

  The compound having the structure represented by the general formula (I) is a single type of compound in which the number of hydroxyl groups (m) and the number of-(O—C (═O) —R) groups (1) are fixed. It is difficult to separate, and it is known that a compound in which several components different in m and l in the formula are mixed is obtained. Therefore, the performance as a mixture in which the number of hydroxyl groups (m) and the number of-(O—C (═O) —R) groups (1) are important is important, and the cellulose acylate film of this embodiment In this case, a compound having a structure represented by the general formula (I) with respect to haze characteristics and a mixing ratio of a component of m = 0 and a component of m> 0 is 45:55 to 0: 100. More preferably, in terms of performance and cost, the mixing ratio of the component m = 0 and the component m> 0 is in the range of 10:90 to 0.1: 99.9. In addition, the component of said m = 0 and the component of m> 0 can be measured by a high performance liquid chromatography by a conventional method.

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

  Although the structural example of the compound which has a monosaccharide residue represented with general formula (I) below is shown, this invention is not limited to these specific examples.

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

  Although the structural example of the compound which has a disaccharide residue represented with general formula (I) below is shown, this invention is not limited to these specific examples.

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

  In general formula (I), m is the total number of hydroxyl groups directly bonded to the monosaccharide or disaccharide residue, and l is directly bonded to the monosaccharide or disaccharide residue. The total number of — (O—C (═O) —R) groups. And it is necessary that 3 ≦ m + 1 ≦ 8, and it is preferable that 4 ≦ m + 1 ≦ 8. Also, l ≠ 0. When l is 2 or more, the — (O—C (═O) —R) groups may be the same as or different from each other.

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

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

  Next, although the preferable example of a compound represented by general formula (I) is shown below, this invention is not limited to these specific examples.

  (Synthesis Example: Synthesis Example of Compound Represented by General Formula (I))

Four-headed Kolben equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen gas inlet tube was charged with 34.2 g (0.1 mol) of sucrose, 180.8 g (0.8 mol) of benzoic anhydride, 379. 7 g (4.8 mol) was charged, the temperature was raised while bubbling nitrogen gas from a nitrogen gas introduction tube with stirring, and an esterification reaction was carried out at 70 ° C. for 5 hours. Next, the inside of the Kolben was depressurized to 4 × 10 ² Pa or less, and after excess pyridine was distilled off at 60 ° C., the inside of the Kolben was depressurized to 1.3 × 10 Pa or less and the temperature was raised to 120 ° C. Most of the acid and benzoic acid formed were distilled off. Then, 1 L of toluene and 300 g of a 0.5% by mass aqueous sodium carbonate solution were added, and the mixture was stirred at 50 ° C. for 30 minutes and then allowed to stand to separate a toluene layer. Finally, 100 g of water is added to the collected toluene layer, and after washing with water at room temperature for 30 minutes, the toluene layer is collected, and toluene is distilled off at 60 ° C. under reduced pressure (4 × 10 2 Pa or less) to thereby give Exemplified Compound 1 A mixture of (a1), exemplary compound 2 (a2), exemplary compound 3 (a3), exemplary compound 4 (a4), and exemplary compound 5 was obtained. When the obtained mixture was analyzed by HPLC and LC-MASS, Exemplified Compound 1 (a1) was 7% by mass, Exemplified Compound 2 (a2) was 58% by mass, Exemplified Compound 3 (a3) was 23% by mass, Exemplified Compound 4 (a4) was 9% by mass, and Exemplified Compound 5 was 3% by mass. In addition, by purifying a part of the obtained mixture by silica gel column chromatography, exemplary compound 1 (a1), exemplary compound 2 (a2), exemplary compound 3 (a3), exemplary compound 4 (100% purity), respectively a4) and Exemplified Compound 5 were obtained.

(Retardation adjuster)
The retardation film according to the present invention may contain a retardation adjusting agent. The retardation adjusting agent is an additive capable of adjusting the retardation development property of the retardation film by its addition. There is no restriction | limiting in particular about the specific structure, A conventionally well-known knowledge can be referred suitably. Moreover, although there exists the retardation adjusting agent which has the effect of adjusting wavelength dispersion simultaneously, you may use this.

  Examples of the retardation adjusting agent that can be used in the present invention include aromatic compounds having two or more aromatic rings as described in EP 911,656A2. Two or more aromatic compounds may be used in combination. The aromatic ring of the aromatic compound includes an aromatic heterocyclic ring in addition to the aromatic hydrocarbon ring. An aromatic heterocyclic ring is particularly preferred, and the aromatic heterocyclic ring is generally an unsaturated heterocyclic ring. Of these, compounds having a 1,3,5-triazine ring are particularly preferred.

  Another example of the retardation adjusting agent is a compound disclosed in Japanese Patent Application Laid-Open No. 2010-163482 as the general formula (I). Specific examples of the general formula (I) are disclosed in paragraphs “0052” to “0058” of the publication. Moreover, the compound currently disclosed by Unexamined-Japanese-Patent No. 2010-163483 as general formula (I) can also be used as a retardation regulator similarly. Specific examples of the general formula (I) are disclosed in paragraphs “0054” to “0068” of the publication.

  It is preferable that a retardation regulator is contained in the quantity of 0.01-20 mass% with respect to 100 mass% of cellulose acylates, More preferably, it is 0.1-10 mass%.

(Plasticizer)
The retardation film of the present invention may contain a plasticizer. Although there is no restriction | limiting in particular about the specific form of a plasticizer, For example, a polyester plasticizer is mentioned. There is no restriction | limiting in particular about the specific structure of a polyester plasticizer, The polyester plasticizer which has an aromatic ring or a cycloalkyl ring in a molecule | numerator can be used. As a polyester plasticizer, the polyester plasticizer represented by the following general formula (a) is mentioned, for example.

(In the formula, B represents a benzene monocarboxylic acid residue or an aliphatic monocarboxylic acid residue, and G represents an alkylene glycol residue having 2 to 12 carbon atoms, an aryl glycol residue having 6 to 12 carbon atoms, or 4 carbon atoms. -12 represents an oxyalkylene glycol residue having -12, A represents an alkylene dicarboxylic acid residue having 4 to 12 carbon atoms or an aryl dicarboxylic acid residue having 6 to 12 carbon atoms, and n represents an integer of 1 or more.)
The polyester plasticizer represented by the general formula (a) is obtained by the same reaction as a normal polyester plasticizer.

  Examples of the benzene monocarboxylic acid component of the polyester plasticizer include benzoic acid, paratertiary butylbenzoic acid, orthotoluic acid, metatoluic acid, p-toluic acid, dimethylbenzoic acid, ethylbenzoic acid, normal propylbenzoic acid, and aminobenzoic acid. , Acetoxybenzoic acid, and the like, each of which can be used alone or as a mixture of two or more.

  The aliphatic monocarboxylic acid component of the polyester plasticizer is preferably an aliphatic monocarboxylic acid having 3 or less carbon atoms, more preferably acetic acid, propionic acid, or butanoic acid, and most preferably acetic acid. When the number of carbon atoms of the monocarboxylic acids used at both ends of the polycondensed ester is 3 or less, the heat loss of the compound does not increase, and no surface failure occurs.

  Further, a monocarboxylic acid having a cycloaliphatic having 3 to 8 carbon atoms is preferred, a monocarboxylic acid having a cycloaliphatic having 6 carbons is more preferred, and cyclohexanecarboxylic acid and 4-methyl-cyclohexanecarboxylic acid are most preferred. . When the number of carbon atoms of the cycloaliphatic monocarboxylic acid used at both ends of the polycondensed ester is 3 or more and 8 or less, the loss on heating of the compound is not increased, and a surface failure does not occur.

  Examples of the alkylene glycol component having 2 to 12 carbon atoms of the polyester plasticizer include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1,3-butanediol, 1,2-propanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethyl-1,3-propanediol (neopentyl glycol), 2,2-diethyl-1,3-propanediol (3,3-dimethylolpentane), 2-n-butyl-2-ethyl-1,3-propanediol (3,3-dimethylolheptane), 3- Methyl-1,5-pentanediol-1,6-hexanediol, 2,2,4-trimethyl-1,3-pentanediol Examples include 2-ethyl-1,3-hexanediol, 2-methyl-1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-octadecanediol, and the like. Can be used singly or as a mixture of two or more. Especially, since C2-C12 alkylene glycol is excellent in compatibility with a cellulose acylate, it is preferable, More preferably, it is C2-C6 alkylene glycol, More preferably, it is C2-C4. Alkylene glycol.

  Examples of the oxyalkylene glycol component having 4 to 12 carbon atoms of the polyester plasticizer include diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, and the like. Or as a mixture of two or more.

  Examples of the alkylene dicarboxylic acid component having 4 to 12 carbon atoms of the polyester plasticizer include succinic acid, maleic acid, fumaric acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, and the like. Can be used singly or as a mixture of two or more. Furthermore, examples of the arylene dicarboxylic acid component having 6 to 12 carbon atoms include phthalic acid, terephthalic acid, isophthalic acid, 1,5-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, and the like.

  The polyester plasticizer preferably has a number average molecular weight of 1,000 to 10,000. By adding a polyester plasticizer having a relatively large number average molecular weight in this way, cellulose acylate oriented at high stretch even when subjected to a stretching treatment under high temperature conditions when producing a film There is an advantageous effect that the elongation at break can be improved by being arranged so as to be interposed between molecules. The number average molecular weight of the polyester plasticizer is preferably 5000 to 9000, more preferably 6000 to 8000.

  The acid value of the polyester plasticizer is preferably 0.5 mgKOH / g or less, more preferably 0.3 mgKOH / g or less. Further, the hydroxyl value of the polyester plasticizer is preferably 25 mgKOH / g or less, more preferably 15 mgKOH / g or less. In addition, an acid value means the milligram number of potassium hydroxide required in order to neutralize the acid (carboxyl group which exists in a sample) contained in 1g of samples. The acid value is measured according to JIS K0070.

  Although the specific structure of a polyester plasticizer is shown below, this invention is not limited only to such a form.

  In formula, n represents the average repeating number of a repeating unit, and is a number of 3.5-47.2. n is preferably 22.9 to 42.4, and more preferably 27.8 to 37.5.

  The retardation film of the present invention may contain a plasticizer other than the polyester plasticizer described above.

  As such a plasticizer, first, among the polyester plasticizers described above, those having a number average molecular weight (Mn) of less than 1000 and those having Mn of more than 10,000 can be mentioned. Specific examples thereof are obvious to those skilled in the art in view of the above description and the common general knowledge as of the filing of the present application, and it is also easy for those skilled in the art to produce such plasticizers. It is.

  In addition to the polyester plasticizer described above, various plasticizers may be added to the retardation film according to an embodiment of the present invention. Examples of such plasticizers include polyhydric alcohol ester plasticizers, glycolate plasticizers, phthalate ester plasticizers, citrate ester plasticizers, fatty acid ester plasticizers, and phosphate ester plasticizers. , Polycarboxylic acid ester plasticizers, acrylic plasticizers, and the like.

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

  The polyhydric alcohol preferably used is represented by the following general formula (b).

(Wherein R1 represents an n-valent organic group, n represents an integer of 2 or more, and OH represents an alcoholic and / or phenolic hydroxyl group.)
Examples of preferred polyhydric alcohols include the following, but the present invention is not limited thereto.

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

  There is no restriction | limiting in particular as monocarboxylic acid used for polyhydric alcohol ester, Well-known aliphatic monocarboxylic acid, alicyclic monocarboxylic acid, aromatic monocarboxylic acid, etc. can be used. It is preferable to use an alicyclic monocarboxylic acid or an aromatic monocarboxylic acid because the moisture permeability and retention of the film can be improved.

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

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

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

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

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

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

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

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

  The glycolate plasticizer is not particularly limited, but for example, alkylphthalylalkyl glycolates can be preferably used. Examples of alkyl phthalyl alkyl glycolates include methyl phthalyl methyl glycolate, ethyl phthalyl ethyl glycolate, propyl phthalyl propyl glycolate, butyl phthalyl butyl glycolate, octyl phthalyl octyl glycolate, methyl phthalyl Ethyl glycolate, ethyl phthalyl methyl glycolate, ethyl phthalyl propyl glycolate, methyl phthalyl butyl glycolate, ethyl phthalyl butyl glycolate, butyl phthalyl methyl glycolate, butyl phthalyl ethyl glycolate, propyl phthalyl butyl Glycolate, butyl phthalyl propyl glycolate, methyl phthalyl octyl glycolate, ethyl phthalyl octyl glycolate, octyl phthalyl methyl glycolate, octyl phthalate Ethyl glycolate, and the like.

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

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

  Examples of the fatty acid ester plasticizer include butyl oleate, methylacetyl ricinoleate, dibutyl sebacate and the like.

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

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

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

(In the formula, R2 represents an (m + n) -valent organic group, m represents an integer of 2 or more, n represents an integer of 0 or more, COOH represents a carboxyl group, OH represents alcoholic and / or phenolic. Represents a hydroxyl group)
Examples of preferred polyvalent carboxylic acids include the following, but the present invention is not limited to these.

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

  On the other hand, the alcohol constituting the polycarboxylic acid ester plasticizer is not particularly limited, and known alcohols and phenols can be used.

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

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

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

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

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

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

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

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

  The alcohols used for the polyvalent carboxylic acid ester plasticizer may be one kind alone or a mixture of two or more kinds.

  The acid value of the polyvalent carboxylic acid ester plasticizer is preferably 1 mgKOH / g or less, and more preferably 0.2 mgKOH / g or less. It is preferable to make the acid value within the above range because the environmental fluctuation of retardation is suppressed.

  Examples of particularly preferred polycarboxylic acid ester plasticizers are shown below, but the present invention is not limited thereto.

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

(polyester)
The retardation film according to the present invention preferably contains the following polyester.

(Polyester represented by general formula (d) or (e))
The retardation film according to the present invention preferably contains a polyester represented by the following general formula (d) or (e).

(In the formula, B1 represents a monocarboxylic acid, G represents a divalent alcohol, A represents a dibasic acid, and B1, G, and A do not contain an aromatic ring. M represents the number of repetitions. )

(In the formula, B2 represents a monoalcohol, G represents a divalent alcohol, A represents a dibasic acid, and B2, G, and A do not contain an aromatic ring. N represents the number of repetitions.)
In the general formulas (d) and (e), B1 represents a monocarboxylic acid component, B2 represents a monoalcohol component, G represents a divalent alcohol component, A represents a dibasic acid component, and these are synthesized. It represents what has been done. B1, B2, G, and A are all characterized by containing no aromatic ring. m and n represent the number of repetitions.

  There is no restriction | limiting in particular as monocarboxylic acid represented by B1, Well-known aliphatic monocarboxylic acid, alicyclic monocarboxylic acid, etc. can be used.

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

  As the aliphatic monocarboxylic acid, a straight-chain or side-chain fatty acid having 1 to 32 carbon atoms can be preferably used. The number of carbon atoms is more preferably 1-20, and particularly preferably 1-12. When acetic acid is contained, the compatibility with cellulose acylate is increased, and it is also preferable to use a mixture of acetic acid and another monocarboxylic acid.

  Preferred aliphatic monocarboxylic acids include formic acid, 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, Saturated fatty acids such as tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, heptacosanoic acid, montanic acid, mellicic acid, and laxelic acid; Examples thereof include unsaturated fatty acids such as acid, oleic acid, sorbic acid, linoleic acid, linolenic acid, and arachidonic acid.

  The monoalcohol component represented by B2 is not particularly limited, and known alcohols can be used. For example, an aliphatic saturated alcohol or aliphatic unsaturated alcohol having a straight chain or a side chain having 1 to 32 carbon atoms can be preferably used. The number of carbon atoms is more preferably 1-20, and particularly preferably 1-12.

  Examples of the divalent alcohol component represented by G include the following, but the present invention is not limited thereto. For example, ethylene glycol, diethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, 1,4-butylene glycol, 1,5-pentanediol, , 6-hexanediol, 1,5-pentylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, etc., among which ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1 , 2-butylene glycol, 1,3-butylene glycol, 1,4-butylene glycol, 1,6-hexanediol, diethylene glycol and triethylene glycol are preferred, and 1,3-propylene glycol, 1,4 Butylene glycol 1,6-hexanediol, diethylene glycol is preferably used.

  The dibasic acid (dicarboxylic acid) component represented by A is preferably an aliphatic dibasic acid or an alicyclic dibasic acid. Examples of the aliphatic dibasic acid include malonic acid, succinic acid, glutaric acid, Adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedicarboxylic acid, dodecanedicarboxylic acid, etc., in particular, aliphatic dicarboxylic acid having 4 to 12 carbon atoms, at least one selected from these is used Can be done. That is, two or more dibasic acids may be used in combination.

  m and n represent the number of repetitions and are preferably 1 or more and 170 or less.

(Polyester represented by general formula (f) or (g))
The retardation film according to the present invention preferably contains a polyester represented by the following general formula (f) or (g).

(In the formula, B1 represents a monocarboxylic acid having 1 to 12 carbon atoms, G represents a divalent alcohol having 2 to 12 carbon atoms, and A represents a dibasic acid having 2 to 12 carbon atoms. B1, G , A does not contain an aromatic ring, and m represents the number of repetitions.)

(In the formula, B2 represents a monoalcohol having 1 to 12 carbon atoms, G represents a divalent alcohol having 2 to 12 carbon atoms, and A represents a dibasic acid having 2 to 12 carbon atoms. B2, G, (A does not contain an aromatic ring. N represents the number of repetitions.)
In the general formulas (f) and (g), B1 represents a monocarboxylic acid component, B2 represents a monoalcohol component, G represents a divalent alcohol component having 2 to 12 carbon atoms, and A represents 2 to 2 carbon atoms. Twelve dibasic acid components are represented and synthesized by them. B1, G, and A do not contain an aromatic ring. m and n represent the number of repetitions. B1 and B2 have the same meanings as B1 and B2 in the general formula (d) or (e) described above. G and A correspond to an alcohol component or a dibasic acid component having 2 to 12 carbon atoms in G and A in the general formula (d) or (e).

  The number average molecular weight of the polyester is 1000 or more and 10,000 or less. If the number average molecular weight is less than 1000, breakage tends to occur at high temperature and high magnification stretching, and if it exceeds 10,000, whitening due to phase separation tends to increase.

  Polycondensation of polyester is performed by a conventional method. For example, a direct reaction of the dibasic acid with a glycol, a hot melt condensation method using the dibasic acid or an alkyl ester thereof, for example, a polyesterification reaction or a transesterification reaction between a methyl ester of a dibasic acid and a glycol. Alternatively, it can be easily synthesized by any method of dehydrohalogenation reaction between acid chloride of these acids and glycol, but it is preferable to synthesize a polyester having a weight average molecular weight not so large by direct reaction.

  Polyester having a high distribution on the low molecular weight side has very good compatibility with cellulose acylate, and after film formation, a cellulose acylate film having low moisture permeability and high transparency can be obtained. A conventional method can be used as a method for adjusting the molecular weight without particular limitation. For example, although depending on the polymerization conditions, when a method of blocking the molecular ends with a monovalent acid or monovalent alcohol is used, the molecular weight is adjusted by adjusting the addition amount of these monovalent raw material compounds. be able to. In this case, it is preferable from the viewpoint of the stability of the polymer to adjust the addition amount of the monovalent acid. For example, acetic acid, propionic acid, butyric acid and the like can be mentioned, but it is preferable to select those which are not distilled out of the system during the polycondensation reaction but are easily distilled off when stopped and removed from the reaction system. For this purpose, a plurality of compounds may be used in combination. In the case of a direct reaction, the weight average molecular weight can also be adjusted by measuring the timing for stopping the reaction based on the amount of water produced during the reaction. In addition, the molecular weight can be adjusted by biasing the number of moles of glycol or dibasic acid to be charged, or the molecular weight can be adjusted by controlling the reaction temperature.

  The polyester is preferably contained in an amount of 1 to 40% by mass with respect to 100% by mass of cellulose acylate, and the polyester represented by the general formula (f) or (g) is in an amount of 2 to 30% by mass. It is preferably included. In particular, it is preferably contained in an amount of 5 to 15% by mass.

(UV absorber)
The retardation film according to the present invention can contain an ultraviolet absorber depending on its application. The ultraviolet absorber is intended to improve durability by absorbing ultraviolet light having a wavelength of 400 nm or less. In particular, the transmittance at a wavelength of 370 nm is preferably 10% or less, more preferably 5% or less, Preferably it is 2% or less. In addition, when the retardation film which concerns on this invention contains a ultraviolet absorber, it is preferable that the said ultraviolet absorber is contained 2 or more types.

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

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

  The UV absorbers preferably used in the present invention are benzotriazole UV absorbers, benzophenone UV absorbers, and triazine UV absorbers, particularly preferably benzotriazole UV absorbers and benzophenone UV absorbers. . In addition, a discotic compound such as a compound having a 1,3,5 triazine ring is also preferably used as the ultraviolet absorber. As the UV absorber, a polymer UV absorber can also be preferably used, and in particular, a polymer type UV absorber described in JP-A-6-148430 is preferably used.

  The method of adding the UV absorber can be added to the dope after dissolving the UV absorber in an alcohol such as methanol, ethanol or butanol, an organic solvent such as methylene chloride, methyl acetate, acetone or dioxolane or a mixed solvent thereof. Or you may add directly in dope composition. Moreover, what does not melt | dissolve in an organic solvent like an inorganic powder should just add to a dope, after using a dissolver and a sand mill in an organic solvent and a cellulose acetate, disperse | distributing.

  Although there is no restriction | limiting in particular about content of the ultraviolet absorber in the retardation film which concerns on this invention, Preferably it is 0.01-10 mass% with respect to 100 mass% of cellulose acylates, More preferably, it is 0.1-0.1 mass%. 5% by mass.

(Infrared absorber)
The retardation film according to the present invention may contain an infrared absorber. Also by adopting such a configuration, the reverse wavelength dispersion of the film can be adjusted.

  The infrared absorber preferably has a maximum absorption in a wavelength region of 750 to 1100 nm, and more preferably has a maximum absorption in a wavelength region of 800 to 1000 nm. Moreover, it is preferable that the infrared absorber has substantially no absorption in the visible region.

  As the infrared absorbing agent, it is preferable to use an infrared absorbing dye or an infrared absorbing pigment, and it is particularly preferable to use an infrared absorbing dye.

  The infrared absorbing dye includes an organic compound and an inorganic compound. It is preferable to use an infrared absorbing dye that is an organic compound. Organic infrared absorbing dyes include cyanine compounds, metal chelate compounds, aminium compounds, diimonium compounds, quinone compounds, squarylium compounds, and methine compounds. The infrared absorbing dye is described in Coloring Materials, 61 [4] 215-226 (1988), and Chemical Industry, 43-53 (1986, May).

  Examining the types of dyes from the viewpoint of infrared absorption function or absorption spectrum, infrared absorbing dyes developed in the technical field of silver halide photographic light-sensitive materials are excellent. Examples of infrared absorbing dyes developed in the technical field of silver halide photographic light-sensitive materials include dihydroperimidine squarylium dyes (described in US Pat. No. 5,380,635 and Japanese Patent Application No. 8-189817), cyanine dyes Nos. 62-123454, 3-138640, 3-221542, 3-226636, 5-313305, 6-43583, Japanese Patent Application No. 7-269097 and European Patent No. 0430244), pyrylium dyes (described in JP-A-3-138640 and JP-A-3-21542), diimonium dyes (described in JP-A-3-138640 and JP-A-3-21542), pyrazolopyridone Dyes (described in JP-A-2-282244), indoaniline dyes (JP-A-5-323500) No. 5-323501), polymethine dyes (Japanese Unexamined Patent Publication Nos. 3-26765 and 4-190343 and European Patent No. 377961), and oxonol dyes (Japanese Unexamined Patent Publication No. 3-9346). Description), anthraquinone dyes (described in JP-A-4-13654), naphthalocyanine dyes (described in US Pat. No. 5,099,899) and naphtholactam dyes (described in European Patent 568267). As for these infrared absorbers, only 1 type may be used independently and 2 or more types may be used together.

  Although there is no restriction | limiting in particular about content of the infrared absorber in the retardation film which concerns on this invention, Preferably it is 0.01-10 mass% with respect to 100 mass% of cellulose acylates, More preferably, it is 0.1-0.1 mass%. 5% by mass.

(Fine particles)
In order to improve the handleability, the retardation film according to the present invention includes, for example, silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, kaolin, talc, calcined calcium silicate, hydrated calcium silicate, and silicic acid. It is preferable to contain inorganic fine particles such as aluminum, magnesium silicate, and calcium phosphate, and fine particles (mat agent) such as a crosslinked polymer. Of these, silicon dioxide is preferable because it can reduce the haze of the film.

  The primary average particle diameter of the fine particles is preferably 20 nm or less, more preferably 5 to 16 nm, and particularly preferably 5 to 12 nm.

  These fine particles preferably form secondary particles having a particle size of 0.1 to 5 μm and are contained in the film, and a preferable average particle size is 0.1 to 2 μm, more preferably 0.2 to 0. .6 μm. Thereby, the unevenness | corrugation about 0.1-1.0 micrometer high can be formed in the film surface, and this can give appropriate slipperiness to the film surface.

  The primary average particle diameter of the fine particles used in the present invention is measured by observing the particles with a transmission electron microscope (magnification 500,000 to 2,000,000 times), observing 100 particles, measuring the particle diameter, and measuring the average. Let the value be the primary average particle size.

  The apparent specific gravity of the fine particles is preferably 70 g / liter or more, more preferably 90 to 200 g / liter, and particularly preferably 100 to 200 g / liter. A higher apparent specific gravity is preferable because a high-concentration dispersion can be produced and haze and aggregates are improved, and it is particularly preferably used when preparing a dope having a high solid content concentration.

  Silicon dioxide fine particles having an average primary particle diameter of 20 nm or less and an apparent specific gravity of 70 g / liter or more are, for example, a mixture of vaporized silicon tetrachloride and hydrogen burned in air at 1000 to 1200 ° C. Can be obtained. For example, Aerosil R812, Aerosil 200V, Aerosil R972V (above, manufactured by Nippon Aerosil Co., Ltd.) are commercially available and can be used.

  The apparent specific gravity described above is calculated by the following equation by taking a certain amount of silicon dioxide fine particles in a graduated cylinder, measuring the weight at this time.

  Examples of the method for preparing the fine particle dispersion used in the present invention include the following three types.

<< Preparation Method A >>
After stirring and mixing the solvent and fine particles, dispersion is performed with a disperser. This is a fine particle dispersion. The fine particle dispersion is added to the dope solution and stirred.

<< Preparation Method B >>
After stirring and mixing the solvent and fine particles, dispersion is performed with a disperser. This is a fine particle dispersion. Separately, a small amount of cellulose acylate is added to the solvent and dissolved by stirring. The fine particle dispersion is added to this and stirred. This is a fine particle addition solution. The fine particle additive solution is sufficiently mixed with the dope solution using an in-line mixer.

<< Preparation Method C >>
Add a small amount of cellulose acylate to the solvent and stir to dissolve. Fine particles are added to this and dispersed by a disperser. This is a fine particle addition solution. The fine particle additive solution is sufficiently mixed with the dope solution using an in-line mixer.

  Preparation method A is excellent in dispersibility of silicon dioxide fine particles, and preparation method C is excellent in that silicon dioxide fine particles are difficult to re-aggregate. Among them, the preparation method B described above is a preferable preparation method that is excellent in both dispersibility of the silicon dioxide fine particles and difficulty in reaggregation of the silicon dioxide fine particles.

《Distribution method》
The concentration of silicon dioxide when the silicon dioxide fine particles are mixed and dispersed with a solvent is preferably 5 to 30% by mass, more preferably 10 to 25% by mass, and most preferably 15 to 20% by mass. A higher dispersion concentration is preferable because liquid turbidity with respect to the added amount tends to be low, and haze and aggregates are improved.

  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 formation of a cellulose acylate.

  The addition amount of fine particles (matting agent) with respect to cellulose acylate is preferably 0.01 to 5.0% by mass, and 0.05 to 1.0% by mass with respect to 100% by mass of cellulose acylate. More preferred is 0.1 to 0.5% by mass. The larger the amount added, the better the dynamic friction coefficient, and the smaller the amount added, the less aggregate.

  As the disperser, a normal disperser can be used. Dispersers can be broadly divided into media dispersers and medialess dispersers. For dispersing the silicon dioxide fine particles, a medialess disperser is preferable from the viewpoint of reducing haze. Examples of the media disperser include a ball mill, a sand mill, and a dyno mill.

  Examples of the medialess disperser include an ultrasonic type, a centrifugal type, and a high pressure type. In the present invention, a high pressure disperser is preferable. The high pressure dispersion device is a device that creates special conditions such as high shear and high pressure by passing a composition in which fine particles and a solvent are mixed at high speed through a narrow tube.

  When processing with a high-pressure dispersion apparatus, for example, the maximum pressure condition inside the apparatus is preferably 9.807 MPa or more in a thin tube having a tube diameter of 1 to 2000 μm. More preferably, it is 19.613 MPa or more. Further, at that time, those having a maximum reaching speed of 100 m / second or more and those having a heat transfer speed of 420 kJ / hour or more are preferable. Examples of the high-pressure dispersion apparatus include an ultra-high pressure homogenizer (trade name: Microfluidizer) manufactured by Microfluidics Corporation and a nanomizer manufactured by Nanomizer, and other manton gorin type high-pressure dispersion apparatuses such as Izumi Food Machinery Co., Ltd. Examples thereof include a homogenizer and UHN-01 manufactured by Sanwa Machinery Co., Ltd.

  In addition, casting a dope containing fine particles so as to be in direct contact with the casting support is preferable because a film having high slip properties and low haze can be obtained.

(Coloring agent)
The retardation film according to the present invention may contain a colorant. The “colorant” means a dye or a pigment. In the present invention, those having an effect of making the color tone of the liquid crystal screen blue, adjusting the yellow index, and reducing haze are particularly preferable. Various dyes and pigments can be used as the colorant, and anthraquinone dyes, azo dyes, phthalocyanine pigments and the like are particularly effective.

≪Method for producing retardation film≫
Although there is no restriction | limiting in particular about the manufacturing method of the phase difference film which concerns on this invention, The manufacturing method using the cellulose acylate obtained by acylation of the cellulose using the ionic liquid mentioned above as a solvent is illustrated preferably. That is, according to another aspect of the present invention, the method includes a step of reacting cellulose with an acylating agent in the presence of an ionic liquid to obtain a cellulose acylate having an acyl group substitution degree of 1.9 to 2.5. A method for producing a retardation film is provided. Hereinafter, the preferable form for manufacturing a phase difference film using the cellulose acylate obtained in this way is demonstrated.

  The retardation film is obtained by stretching a film obtained by casting a cellulose composition containing cellulose acylate and an additive on a support in the longitudinal direction and / or the transverse direction simultaneously or sequentially. Is obtained. Examples of such a production method include a solution casting method and a melt casting method, both of which can be employed, and a solution casting method is particularly preferably used.

  The production of the retardation film by the solution casting method includes, for example, a step of preparing a dope by dissolving cellulose acylate and an additive in a solvent, a step of casting on an endless metal support that moves the dope indefinitely , A process of drying the cast dope as a web, a process of stretching, a process of drying, a process of winding up the finished film, and the like.

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

  The solvent used for the preparation of the dope may be used alone or in combination of two or more, but it is preferable in terms of production efficiency to use a mixture of a good solvent and a poor solvent of cellulose acylate, A larger amount of good solvent is preferred from the viewpoint of the solubility of cellulose acylate.

  The preferable range of the mixing ratio of the good solvent and the poor solvent is 70 to 98% by mass for the good solvent and 2 to 30% by mass for the poor solvent. Here, regarding the good solvent and the poor solvent, those that dissolve the cellulose acylate used alone are defined as good solvents, and those that swell or do not dissolve alone are defined as poor solvents. Therefore, depending on the substitution degree of cellulose acylate, even the same solvent may be a good solvent or a poor solvent.

  The good solvent candidate is not particularly limited, and examples thereof include organic halogen compounds such as methylene chloride, dioxolanes, acetone, methyl acetate, and methyl acetoacetate. Particularly preferred is methylene chloride or methyl acetate.

  Moreover, although it does not specifically limit as a candidate of a poor solvent, For example, methanol, ethanol, n-butanol, cyclohexane, cyclohexanone etc. are used preferably. Moreover, it is preferable that 0.01-2 mass% of water is contained in dope. In addition, the solvent used for melt | dissolving a cellulose acylate at the time of preparation of dope is collect | recovered after removing from a film by drying at the film-forming process, and is normally recycled.

  The recovered solvent may contain trace amounts of additives added to cellulose acylate, such as plasticizers, UV absorbers, polymers, and monomer components. Can be purified and reused if necessary.

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

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

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

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

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

  A preferable heating temperature is 45 to 120 ° C, more preferably 60 to 110 ° C, and still more preferably 70 ° C to 105 ° C. The pressure is adjusted so that the solvent does not boil at the set temperature. Alternatively, a cooling dissolution method is also preferably used, whereby cellulose acylate can be dissolved in a solvent such as methyl acetate.

  Next, this cellulose acylate solution is filtered using a suitable filter medium such as filter paper. As the filter medium, it is preferable that the absolute filtration accuracy is small in order to remove insoluble matters and the like, but there is a problem that the filter medium is likely to be clogged if the absolute filtration accuracy is too small. For this reason, a filter medium with an absolute filtration accuracy of 0.008 mm or less is preferable, a filter medium with 0.001 to 0.008 mm is more preferable, and a filter medium with 0.003 to 0.006 mm is more preferable. There are no particular restrictions on the material of the filter medium, and ordinary filter media can be used. However, plastic filter media such as polypropylene and Teflon (registered trademark), and metal filter media such as stainless steel do not drop off fibers. preferable. It is preferable to remove and reduce impurities, particularly bright spot foreign matter, contained in the raw material cellulose acetate by filtration. The dope can be filtered by a normal method, but the method of filtering while heating at a temperature not lower than the boiling point of the solvent at normal pressure and in a range where the solvent does not boil under pressure is the filtration pressure before and after filtration. The increase in the difference (referred to as differential pressure) is small and preferable. The preferable temperature at the time of filtration is 45-120 degreeC, 45-70 degreeC is more preferable, and it is further more preferable that it is 45-55 degreeC. A smaller filtration pressure is preferred. The filtration pressure is preferably 1.6 MPa or less, more preferably 1.2 MPa or less, and further preferably 1.0 MPa or less.

  Subsequently, the dope prepared above is cast on an endless metal support that moves infinitely (casting process; casting process).

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

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

  A preferable support temperature is 0 to 55 ° C, and more preferably 25 to 50 ° C. Alternatively, it is also a preferable method that the web is gelled by cooling and peeled from the drum in a state containing a large amount of residual solvent.

  The method for controlling the temperature of the metal support is not particularly limited, and there are a method of blowing hot air or cold air, and a method of contacting hot water with the back side of the metal support. It is preferable to use warm water because heat transfer is performed efficiently, so that the time until the temperature of the metal support becomes constant is short. When warm air is used, wind at a temperature higher than the target temperature may be used.

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

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

(In the formula, M represents the mass of a sample collected during or after the production of the web or film, and N is the mass after heating the sample at 115 ° C. for 1 hour.)
Furthermore, the film obtained by casting the dope is dried as a web. In this drying step, it is preferable that the web is peeled off from the metal support and further dried to make the residual solvent amount 1% by mass or less. More preferably, it is 0.1 mass% or less, Most preferably, it is 0-0.01 mass%. In the drying process, a roll drying method (a method in which webs are alternately passed through a plurality of rolls arranged above and below) and a method of drying while transporting the web by a tenter method are adopted. The means for drying the web is not particularly limited, and can be generally performed with hot air, infrared rays, a heating roll, microwave, or the like, but from the viewpoint of simplicity, it is preferably performed with hot air. The drying temperature in the web drying process is preferably increased stepwise from 40 to 200 ° C.

  The method for obtaining the cellulose acylate web by the solution casting method has been described above, but the retardation film of the present invention is also preferably produced by the melt casting method from the viewpoint of production cost. The molding method by melt casting that heats and melts without using the solvent (for example, methylene chloride, etc.) used in the solution casting method, more specifically, melt extrusion molding method, press molding method, inflation method, injection molding method And can be classified into blow molding, stretch molding and the like. Among these, the melt extrusion method is excellent for obtaining a film having excellent mechanical strength and surface accuracy. There is no particular limitation on the specific method for obtaining the cellulose acylate web by the melt casting method, and conventionally known knowledge can be appropriately referred to.

  Subsequently, the web obtained by the solution casting method or the melt casting method as described above is stretched. This stretching treatment can be carried out simultaneously or successively at an angle θ from the width direction (0 ° <θ <90 °) or as biaxial stretching or uniaxial stretching.

  Although there is no restriction | limiting in particular about the extending | stretching conditions at the time of performing an extending | stretching process, It is especially preferable to extend | stretch in the width direction (lateral direction) with the tenter system which hold | grips the both ends of the peeled film (web) with a clip etc. Moreover, it is preferable that the peeling tension from a support body shall be 300 N / m or less.

  By adjusting the conditions during the stretching treatment, the film thickness and retardation value of the resulting film can be controlled.

  For example, the retardation can be changed by lowering or increasing the tension in the longitudinal direction. In addition, the retardation can be changed by successively or simultaneously biaxially or uniaxially stretching the film in the longitudinal direction (film forming direction; MD direction) and in the direction perpendicular to the film plane (width direction). Can do.

  The stretching ratio in the biaxial direction perpendicular to each other is not particularly limited, but when producing a retardation film that uses the retardation film as a polarizing plate protective film, the stretching ratio is at least 1.1 times in the width direction. It is preferable to perform stretching. As a more preferable form of the draw ratio, it is preferable to finally make the range 0.8 to 1.5 times in the casting direction and 1.1 to 2.0 times in the width direction, respectively, and 0 in the casting direction. It is more preferable to carry out in the range of 0.8 to 1.1 times and 1.3 to 1.7 times in the width direction, and particularly preferably in the range of 1.3 to 1.5 times in the width direction.

  The stretching temperature is preferably 120 ° C. to 200 ° C., more preferably 130 ° C. to 170 ° C., and more preferably 140 ° C. to 160 ° C. or less. The amount of residual solvent in the film during the stretching treatment is preferably 20 to 0%, more preferably 15 to 0%. More specifically, for example, it is preferable that the residual solvent is stretched by 11% at 155 ° C., or the residual solvent is stretched by 2% at 155 ° C. Alternatively, the residual solvent is preferably stretched at 11% at 160 ° C., or the residual solvent is preferably stretched at less than 1% at 160 ° C.

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

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

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

  In addition, after the above-described stretching, a further drying step is performed so that the residual solvent amount is preferably 1% by mass or less, more preferably 0.1% by mass or less, and particularly preferably 0 to 0.01% by mass. % Or less. The drying temperature after stretching is preferably 125 ° C. or higher, and more preferably 140 ° C. or higher. If the temperature exceeds 150 ° C., the film tends to approach the Tg of the film, which may cause a decrease in retardation or misalignment of the orientation angle, which is not preferable.

  Finally, a film winding process can be performed. A winding process winds up a film on a winding roll, keeping the shortest distance between the outer peripheral surface of a cylindrical winding film and the outer peripheral surface of the mobile conveyance roll immediately before this constant. In addition, a means such as a static elimination blower for removing or reducing the surface potential of the film is provided in front of the winding roll.

  The winding machine relating to the production of the retardation film according to the present invention may be a commonly used winding machine such as a constant tension method, a constant torque method, a taper tension method, a program tension control method with a constant internal stress. It can be wound up by the method. In addition, it is preferable that the initial winding tension at the time of winding of a polarizing plate protective film is 90.2-300.8 N / m.

  In the film winding process, the film is preferably wound under environmental conditions of a temperature of 20 to 30 ° C. and a humidity of 20 to 60% RH. Thus, the tolerance of the humidity change of thickness direction retardation (Rt) improves by prescribing | regulating the temperature and humidity in the winding-up process of a film.

  If the temperature in the winding process is less than 20 ° C., wrinkles are generated and the film winding quality is deteriorated, which is unpractical. If the temperature in the film winding process exceeds 30 ° C., wrinkles are also generated, and the film winding quality is deteriorated, so that it cannot be put into practical use.

  Moreover, if the humidity in the film winding process is less than 20% RH, it is not preferable because it is easily charged and cannot be put into practical use due to deterioration in film winding quality. If the humidity in the film winding process exceeds 60% RH, the winding quality, sticking failure, and transportability deteriorate, which is not preferable.

  When winding the film into a roll, the winding core may be of any material as long as it is a cylindrical core, but is preferably a hollow plastic core, and the plastic material is heat treated. Any heat-resistant plastic that can withstand the temperature may be used, and examples thereof include phenol resins, xylene resins, melamine resins, polyester resins, and epoxy resins. A thermosetting resin reinforced with a filler such as glass fiber is preferred. For example, a hollow plastic core: a wound core made of FRP and having an outer diameter of 6 inches (1 inch = 2.54 cm) and an inner diameter of 5 inches is used.

  The number of windings to these winding cores is preferably 100 windings or more, more preferably 500 windings or more, the winding thickness is preferably 5 cm or more, and the width of the film substrate is 80 cm or more. It is preferably 1 m or more.

  Although the film thickness of the retardation film according to the present invention varies depending on the purpose of use, the finished film is preferably 10 to 500 μm. In particular, the lower limit is 20 μm or more, preferably 25 μm or more. The upper limit is 150 μm or less, preferably 120 μm or less. A particularly preferable range is 35 to 90 μm. When the retardation film also serves as a polarizing plate protective film, if the film is thick, the polarizing plate after polarizing plate processing becomes too thick. Especially in liquid crystal display devices used for notebook computers and mobile electronic devices, it is thin and lightweight. Not suitable for. On the other hand, if the film is thin, it is difficult to develop retardation as a retardation film. In addition, the moisture permeability of the film increases, and the ability to protect the polarizer from humidity decreases, which is not preferable.

  The stretching process is not limited to the stretching process performed in the state of the web, but may be performed after the web is dried and wound. At that time, the web may be stretched before or during drying.

  The slow axis or the fast axis of the retardation film exists in the film plane, and θ1 is −1 to + 1 °, preferably −0.5 to + 0.5 °, where θ1 is an angle with the stretching direction. To be. This θ1 can be defined as an orientation angle, and θ1 can be measured using an automatic birefringence meter (KOBRA-21ADH, manufactured by Oji Scientific Instruments). That each θ1 satisfies the above relationship contributes to obtaining a high brightness enhancement effect and an antireflection effect in a liquid crystal display device, and contributing to obtaining a crosstalk improvement effect in a stereoscopic display device, The organic EL display device contributes to obtaining an antireflection effect.

  Further, when the cellulose ester film according to the present invention is used in a multi-domain VA mode as a retardation film, the retardation film is arranged in the above region with the fast axis of the retardation film being θ1. This can contribute to improvement of display image quality.

  In the retardation film according to the present invention, it is particularly preferable that the retardation value distribution fluctuation is smaller from the viewpoint of preventing color unevenness and the like. Specifically, the distribution of retardation Ro in the in-plane direction of the retardation film is preferably adjusted to 5% or less, more preferably 2% or less, and particularly preferably 1.5% or less. The distribution of retardation Rt in the thickness direction of the film is preferably adjusted to 10% or less, more preferably 2% or less, and particularly preferably 1.5% or less. In addition, the value of retardation (Ro, Rt) is calculated | required by a following formula.

(In the formula, nx represents the refractive index in the slow axis direction in the film plane, ny represents the refractive index in the fast axis direction in the film plane, nz represents the refractive index in the film thickness direction, and d represents the film. The refractive index is measured at a wavelength of 546 nm under an environment of 25 ° C. and 55% RH)
The refractive index is an Abbe refractometer (4T), the film thickness is a commercially available micrometer, and the retardation value is an automatic birefringence meter (KOBRA-21ADH, manufactured by Oji Scientific Instruments). Each can be measured.

  In the production of the retardation film, the roll length is 10 to 5000 m, preferably 50 to 4500 m in consideration of productivity and transportability. The width of the film at this time is the width of the polarizer or the production line. A suitable width can be selected. A film with a predetermined width may be manufactured and wound into a roll shape, and may be used for polarizing plate processing. Also, after a film having a desired double width or more is manufactured and wound on a roll, the target width is cut. Such a roll may be used for polarizing plate processing. In addition, when manufacturing a film with a predetermined width and winding up in roll shape and using for polarizing plate processing, a film width becomes like this. Preferably it is 1.8-2.5m, More preferably, it is 1.9-2.4m. It is.

  In the production of the retardation film, functional layers such as an antistatic layer, a hard coat layer, a slippery layer, an adhesive layer, an antiglare layer, and a barrier layer may be applied before and / or after stretching. Good. At this time, various surface treatments such as corona discharge treatment, plasma treatment, and chemical treatment can be performed as necessary. Specific examples include the method described in paragraphs 225 to 349 of JP-A-2008-209595.

  In the film forming process, the clip gripping portions at both ends of the cut film are crushed, or after granulating as necessary, and then used as film raw materials of the same type or different types of film raw materials. Can be reused as

  Moreover, the film of a laminated structure can also be produced by coextruding compositions having different additive concentrations such as the sugar ester compound, the retardation adjusting agent, the plasticizer, the ultraviolet absorber, and the matting agent. For example, a film having a structure of skin layer / core layer / skin layer can be produced. For example, fine particles are highly effective when added to the skin layer. In particular, if fine particles are added to the skin layer on the side in contact with the belt or drum, effects such as imparting slipperiness by the addition of fine particles can be effectively expressed. The plasticizer and the ultraviolet absorber can be contained in the core layer more than the skin layer, and may be contained only in the core layer. The sugar ester compound is preferably uniformly contained in all of the skin layer and the core layer. In addition, the type of plasticizer and UV absorber can be changed between the core layer and the skin layer. For example, the skin layer contains a low-volatile plasticizer and / or UV absorber, and the core layer has excellent plasticity. It is also possible to add a plasticizer or an ultraviolet absorber excellent in ultraviolet absorption. The glass transition temperature of the skin layer and the core layer may be different, and the glass transition temperature of the core layer is preferably lower than the glass transition temperature of the skin layer. At this time, the glass transition temperatures of both the skin and the core can be measured, and an average value calculated from these volume fractions can be defined as the glass transition temperature Tg and similarly handled. Moreover, the viscosity of the melt at the time of melt casting may be different between the skin layer and the core layer, and the viscosity of the skin layer> the viscosity of the core layer or the viscosity of the core layer ≧ the viscosity of the skin layer may be used.

  The retardation film according to the present invention has a dimensional stability of ± 2.0 when measured at 80 ° C. and 90% RH, based on the dimensions of the film left at 25 ° C. and 55% RH for 24 hours. %, Preferably less than 1.0%, more preferably less than 0.5%. When using the retardation film according to the present invention as a polarizing plate protective film, if the retardation film itself is within the above range, the retardation retardation value and the orientation angle deviate from the initial settings. Therefore, display quality is not deteriorated, which is preferable.

≪Usage≫
(Liquid crystal display device)
The retardation film according to the present invention is used in, for example, a liquid crystal display device. In this case, the retardation film preferably has a function as a polarizing plate protective film for a liquid crystal display device. In this case, Ro and Rth of the retardation film are respectively

Is preferably satisfied. It can be said that such a form has a retardation value suitable for improving the display quality of a VA mode or TN mode liquid crystal cell.

  The in-plane retardation Ro is a configuration in which two polarizing plates are arranged in crossed Nicols and a liquid crystal cell is arranged between the polarizing plates when the polarizing plate is observed obliquely from the normal line of the display surface. Compensates mainly for light leakage caused by deviation from the crossed Nicols state. The retardation Rt in the thickness direction mainly compensates for the birefringence of the liquid crystal cell similarly observed when viewed from an oblique direction when the liquid crystal cell is in the black display state in the TN mode or VA mode, particularly in the MVA mode. To contribute.

  Then, the detail of the polarizing plate which used the retardation film which concerns on this invention as a protective film of one side of a retardation film and a polarizer is demonstrated.

  The polarizing plate can be produced by a general method. The back surface side of the cellulose ester film according to the present invention is subjected to alkali saponification treatment, and the treated film is bonded to at least one surface of a polarizer to produce a polarizing plate.

  Here, the polarizer, which is the main component of the polarizing plate, is an element that passes only light having a plane of polarization in a certain direction, and a typical polarizer currently known is a polyvinyl alcohol polarizing film. There are one in which iodine is dyed on a polyvinyl alcohol film and one in which a dichroic dye is dyed. For the polarizer, a polyvinyl alcohol aqueous solution is formed into a film and dyed by uniaxial stretching or dyed or uniaxially stretched and then preferably subjected to a durability treatment with a boron compound. . On the surface of the polarizer, one side of the cellulose ester film according to the present invention is bonded to form a polarizing plate. It is preferably bonded with a water-based adhesive mainly composed of completely saponified polyvinyl alcohol or the like.

  On the other surface of the polarizer, the retardation film according to the present invention may be used (see Examples described later), or another polarizing plate protective film may be used. With respect to the retardation film according to the present invention, a commercially available cellulose ester film can be used as the polarizing plate protective film used on the other surface. As a commercially available cellulose ester film, for example, Konica Minoltack KC8UX, KC5UX, KC8UCR3, KC8UCR4, KC8UCR5, KC8UY, KC4UA, KC4UY, KC4UE, KC8UE-KC8UY-HA, KC8UX-H8, -NC, KC4UXW-RHA-NC (above, manufactured by Konica Minolta Opto Co., Ltd.) and the like are preferably used. Alternatively, it is also preferable to use a polarizing plate protective film that also serves as an optical compensation film having an optical anisotropic layer formed by aligning liquid crystal compounds such as discotic liquid crystal, rod-shaped liquid crystal, and cholesteric liquid crystal. For example, the optically anisotropic layer can be formed by the method described in JP-A-2003-98348. By using it in combination with the retardation film according to the present invention, it is possible to obtain a polarizing plate having excellent planarity and a stable viewing angle expansion effect. In addition, as a polarizing plate protective film located in the side far from a liquid crystal cell, or on the said film, it is also possible to arrange | position the film which has other functionality, when improving the quality of a display apparatus. For example, anti-reflection (anti-reflection (AR)), anti-glare (anti-glare (AG)), scratch resistance (hard coat (HC)), low reflection (low reflection (LR)), dust adhesion prevention, brightness improvement, anti-static A film containing a known functional layer as a display for antifouling and back coating can be used as a polarizing plate protective film. Or you may affix separately the film containing these functional layers on the surface of polarizing plate protective films, such as a general purpose TAC film.

  The polarizing plate produced as described above can be constituted by further bonding a protective film on one surface and a separate film on the other surface. The protective film and the separate film are used for the purpose of protecting the polarizing plate at the time of shipping the polarizing plate and at the time of product inspection. In this case, the protect film is bonded for the purpose of protecting the surface of the polarizing plate, and is used on the side opposite to the surface where the polarizing plate is bonded to the display panel. Moreover, a separate film is used in order to cover the contact bonding layer bonded to a panel, and is used for the surface side which bonds a polarizing plate to a liquid crystal cell.

  This polarizing plate is used for MVA (Multi-domain Vertical Alignment) mode, PVA (Patterned Vertical Alignment) mode, CPA (Continuous Pinweal Alignment-P) mode, OCB (Optical Compensated InP) Can be.

  By incorporating the polarizing plate with the retardation film according to the present invention into a liquid crystal display device, a liquid crystal display device with improved backlight transmission can be produced. It is preferably used for a liquid crystal display device for outdoor use such as a liquid crystal display device and digital signage.

  In addition, the use in the liquid crystal display device of the retardation film which concerns on this invention is not restricted to what was mentioned above. Depending on the case, in the polarizing plate of a liquid crystal display device, it may be used as an optical film which is located in the opposite side to the liquid crystal cell of the said polarizing plate, and has only a function as a protective film. In this case, since retardation development is not required, strict control of the retardation value as described above is unnecessary. However, since the above-described operational effects that the film develops are obtained in the same manner, such a form is also a preferred embodiment of the present invention.

  Further, when considering application to a polarizing plate used in, for example, a three-dimensional (3D) liquid crystal display device, in the polarizing plate of the above-described form, for example, the retardation film (polarizing plate) according to the present invention with respect to a polarizer. A retardation film (λ / 4 film) can be disposed in place of the protective film located on the surface (viewing side) opposite to the surface (also having a function as a protective film).

  According to such a form, it is possible to reduce crosstalk, luminance reduction, color change, etc. when tilting the head when viewing a stereoscopic (3D) image, and it is possible to maintain excellent visibility in the usage environment. Thus, a three-dimensional (3D) liquid crystal display device having higher durability against the use environment can be obtained.

  At this time, the retardation film that can be disposed in place of the protective film is not particularly limited, and for example, a conventionally known retardation film can be used. Examples of such conventionally known retardation films include those made of cycloolefin resin, those made by tilting a liquid crystal polymer made of discotic liquid crystal or rod-like nematic liquid crystal, and those made of polycarbonate. Of course, the retardation film according to the present invention may be disposed in place of the protective film described above. Here, for the retardation film formed by tilting the liquid crystal polymer, a layer (support layer) that functions as a support and an alignment film formed thereon are formed to form the retardation film. A phase difference film is required by separately preparing a body and further applying a liquid crystal polymer thereon. For this reason, in a form in which a retardation film made of a liquid crystal polymer is disposed on one side of a polarizer, a layer derived from a laminate of the support layer and the alignment film is also provided on at least one surface of the retardation film. It will also exist. Therefore, it can be said that this form is not necessarily preferable from the viewpoint of thinning the liquid crystal display device. However, such a form may be employed as long as the liquid crystal polymer can be directly processed.

  In any of these forms, similarly to the above, antireflection (antireflection (AR)), antiglare (antiglare (AG)), scratch resistance (hard coat (HC)), low reflection (low reflection (LR) (LR) )) Retardation film placed in place of a protective film on the viewing side instead of a film containing a known functional layer as a display for preventing dust adhesion, improving brightness, preventing antistatic, antifouling, and back coating You may laminate | stack further on. However, it is not advisable to directly arrange these functional layers on a retardation film made of the above-mentioned cycloolefin resin or a retardation film formed by tilting and aligning a liquid crystal polymer made of a discotic liquid crystal or a rod-like nematic liquid crystal. It is difficult from the viewpoint. Therefore, when providing a functional layer on these retardation films, it is preferable to laminate | stack the said functional layer, for example after apply | coating the hard-coat layer containing a cellulose ester on a retardation film as an adhesive layer. On the other hand, when the retardation film according to the present invention is arranged in place of the protective film on the viewing side, the arrangement of such an intermediate layer (adhesive layer) is derived from its excellent adhesion to the polarizer. This is preferable because it can be omitted. However, in some cases, a hard coat layer containing cellulose acylate may be provided as an adhesive layer.

  As mentioned above, although the usage form of the retardation film which concerns on this invention was demonstrated in detail, it can be used also for another use. For example, the retardation film according to the present invention can be used as a brightness enhancement film. As a layer structure in which the retardation film according to the present invention is used as a brightness enhancement film, the retardation film according to the present invention is arranged on one surface of a polarizer and the other surface is conventionally known as a protective film for a polarizing plate. A cellulose ester film (for example, cellulose acetate having no or small retardation), and further comprising a cholesteric liquid crystal on the surface opposite to the polarizer of the retardation film according to the present invention. The form of arranging the layers is exemplified.

(Organic EL display device)
The retardation film according to the present invention can also be used for an antireflection film disposed in an organic EL display device. In this case, the retardation film Ro is

Is preferably satisfied. The retardation film having such a high in-plane retardation (Ro) can function as a circularly polarizing plate (λ / 4 plate). Here, the circularly polarizing plate (λ / 4 plate) refers to a retardation plate having a function of converting linearly polarized light having a specific wavelength into circularly polarized light (or circularly polarized light into linearly polarized light). The circularly polarizing plate (λ / 4 plate) is designed so that the in-plane retardation (Ro) of the layer is about 1/4 with respect to a predetermined wavelength of light (usually in the visible light region).

  When the retardation film according to the present invention has the function of a circularly polarizing plate (λ / 4 plate), when the angle (θ2) of the slow axis with respect to the longitudinal direction of the film is “substantially 45 °”, circularly polarized light The retardation film according to the present invention having a function as a plate (λ / 4 plate) can be produced with high productivity.

  In other words, the above-described θ2 is preferably “substantially 45 °”, and “substantially 45 °” means 40 to 50 °. More specifically, the angle (θ2) of the slow axis with respect to the longitudinal direction of the film is preferably 41 to 49 °, more preferably 42 to 48 °, and further preferably 43 to 47 °. Preferably, it is 44 to 46 degrees.

  Thus, a retardation film having a slow axis angle (θ2) of substantially 45 ° with respect to the longitudinal direction of the film can be produced, for example, by adopting an oblique stretching process (Examples and figures described later). 1). Specifically, for example, a method of giving an inclination angle to the orientation axis by stretching with a feed force at different speeds in the horizontal and vertical directions using a tenter can be used. (For example, JP-A-3-182701, JP-A-2000-9912, JP-A-1-237601, JP-A-2003-342384, JP-A-2008-110573, JP-A-2002-86554 JP, 2011-11434, etc.). Moreover, you may use the method of giving the inclination-angle to an orientation axis | shaft by the path | route difference as described in the patent 4270429 gazette. )

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

≪Method for evaluating properties of cellulose acylate≫
(Acyl group substitution degree)
The acyl group substitution degree of cellulose acylate was measured according to ASTM-D817-96.

(Half width of peak in composition distribution of acyl group substitution degree)
The half width of the peak in the composition distribution of the degree of acyl group substitution was determined as a value in units of elution time from the peak of the elution curve by performing high performance liquid chromatography (HPLC) analysis under the following conditions. The sample solution was subjected to HPLC analysis after being filtered through a 0.2 μm membrane filter. On the other hand, the relationship between the elution time and the acyl group substitution degree was determined, and the half-value width of the elution time unit was converted into the half-value width of the acyl group substitution degree unit by linear function approximation.
Apparatus: Agilent LC1100 (manufactured by Agilent Technologies)
Column used: Novapak phenyl (Waters) 3.9mmφ × 150mm
Eluent: CHCl ₃ / methanol (MeOH) (9/1, v / v): MeOH / H ₂ O (8/1, v / v) = 20/80 → 28 min → CHCl ₃ / MeOH (9/1, v / v) = 100
Flow rate: 0.7 ml / min
Column open: 30 ° C
Detector: ELSD (Evaporative Light Scattering Detector) ELS • 1000 (PL)
Evaporation temperature: 75 ° C Neprizer temperature: 60 ° C Gas flow rate: N ₂ , 0.7 SLM (Standard liter / min., Latm, 0 ° C)
Sample: CHCl ₃ / MeOH (9/1, v / v) solution, 0.1 w / v%
Repeated analysis: n = 2
Injection volume: 20 μl
(Percentage of cellulose acylate included in half width in composition distribution)
From the elution curve by the HPLC analysis performed above, the ratio of the cellulose acylate contained in the half width was obtained as the peak area ratio contained in the half width specified above.

≪Method for evaluating physical properties of retardation film≫
(Ro (546) and Rth (546))
A 35 mm × 35 mm sample was cut out from the obtained retardation film, conditioned at 25 ° C. and 55% RH for 2 hours, and measured from the vertical direction at 546 nm with an automatic birefringence meter (KOBRA-21ADH, manufactured by Oji Scientific Instruments). It calculated from the following formula | equation from the extrapolated value of the measured value and the retardation value measured similarly, tilting the film surface.

(Where nx is the refractive index in the slow axis direction in the film plane, ny is the refractive index in the fast axis direction in the film plane, nz is the refractive index in the thickness direction of the film, and d is (The thickness of the film (nm).)
(Internal haze)
The internal haze of the obtained retardation film was measured by the method described in JP-A-2009-286931. With one film sample, the measuring instrument was NDH2000 manufactured by Nippon Denshoku Industries Co., Ltd., and the measurement was performed in accordance with JIS-K7136.

≪Example of cellulose acylate production≫
(Production Example 1: Production of CE-1)
Cellulose (dissolved pulp manufactured by Nippon Paper Industries Co., Ltd., degree of polymerization) vacuum-dried at 90 ° C. for 12 hours to 100 parts by weight of ionic liquid (1-butyl-3-methylimidazolium chloride, manufactured by Aldrich) vacuum-dried at 90 ° C. for 12 hours (About 750, about 3 mm square sheet form) 5 parts by weight was added and stirred at 80 ° C. for 2 hours in a nitrogen atmosphere to dissolve the cellulose in the ionic liquid. 3.0 equivalents of acetic anhydride was added as an acylating agent, and the mixture was stirred at 60 ° C. for 0.50 hours under a nitrogen atmosphere. Then, the reaction liquid was thrown into 1500 weight part of water, and cellulose acetate (CE-1) was deposited. The precipitated CE-1 was separated by filtration, washed with water using 100 parts by weight of water and separated by filtration three times, and then vacuum-dried at 80 ° C. for 4 hours.

  For the obtained CE-1, the acyl group substitution degree, the half width of the peak in the composition distribution of the acyl group substitution degree, and the ratio of cellulose acylate contained in the half width in the composition distribution were measured. The results are shown in Table 1 below.

(Production Example 2: Production of CE-2)
Cellulose (dissolved pulp manufactured by Nippon Paper Industries Co., Ltd., degree of polymerization) vacuum-dried at 90 ° C. for 12 hours to 100 parts by weight of ionic liquid (1-butyl-3-methylimidazolium chloride, manufactured by Aldrich) vacuum-dried at 90 ° C. for 12 hours (About 750, about 3 mm square sheet form) 5 parts by weight was added and stirred at 80 ° C. for 2 hours in a nitrogen atmosphere to dissolve the cellulose in the ionic liquid. 3.0 equivalents of acetic anhydride was added as an acylating agent, and the mixture was stirred at 80 ° C. for 0.50 hours under a nitrogen atmosphere. Thereafter, the reaction solution was added to 1500 parts by weight of water to precipitate cellulose acetate (CE-2). The precipitated CE-2 was separated by filtration, washed with 100 parts by weight of water and filtered three times, and then vacuum-dried at 80 ° C. for 4 hours.

  For the obtained CE-2, the acyl group substitution degree, the half width of the peak in the composition distribution of the acyl group substitution degree, and the ratio of cellulose acylate contained in the half width in the composition distribution were measured. The results are shown in Table 1 below.

(Production Example 3: Production of CE-3)
Cellulose vacuum-dried at 90 ° C for 12 hours to 100 parts by weight of ionic liquid (1-butyl-3-methylimidazolium acetate, manufactured by Aldrich) vacuum-dried at 90 ° C for 12 hours (dissolved pulp manufactured by Nippon Paper Industries Co., Ltd., degree of polymerization) (About 750, about 3 mm square sheet form) 5 parts by weight was added and stirred at 80 ° C. for 2 hours in a nitrogen atmosphere to dissolve the cellulose in the ionic liquid. As an acylating agent, 3.6 equivalents of acetic anhydride was added and stirred at 40 ° C. for 2 hours under a nitrogen atmosphere. Then, the reaction liquid was thrown into 1500 weight part of water, and the cellulose acetate (CE-3) was deposited. The precipitated CE-3 was separated by filtration, washed with 100 parts by weight of water and filtered three times, and then vacuum-dried at 80 ° C. for 4 hours.

  For the obtained CE-3, the acyl group substitution degree, the half width of the peak in the composition distribution of the acyl group substitution degree, and the ratio of cellulose acylate contained in the half width in the composition distribution were measured. The results are shown in Table 1 below.

(Production Example 4: Production of CE-4)
Cellulose (dissolved pulp manufactured by Nippon Paper Industries Co., Ltd., degree of polymerization) vacuum-dried at 90 ° C. for 12 hours to 100 parts by weight of ionic liquid (1-butyl-3-methylimidazolium chloride, manufactured by Aldrich) vacuum-dried at 90 ° C. for 12 hours (About 750, about 3 mm square sheet form) 5 parts by weight was added and stirred at 80 ° C. for 2 hours in a nitrogen atmosphere to dissolve the cellulose in the ionic liquid. As an acylating agent, 3.6 equivalents of acetic anhydride was added, and the mixture was stirred at 80 ° C. for 1.5 hours under a nitrogen atmosphere. Thereafter, the reaction solution was added to 1500 parts by weight of water to precipitate cellulose acetate (CE-4). The precipitated CE-4 was separated by filtration, washed with 100 parts by weight of water and filtered three times, and then vacuum-dried at 80 ° C. for 4 hours.

  For the obtained CE-4, the acyl group substitution degree, the half width of the peak in the composition distribution of the acyl group substitution degree, and the ratio of cellulose acylate contained in the half width in the composition distribution were measured. The results are shown in Table 1 below.

(Production Example 5: Production of CE-5)
Cellulose (dissolved pulp manufactured by Nippon Paper Industries Co., Ltd., degree of polymerization) vacuum-dried at 90 ° C. for 12 hours to 100 parts by weight of ionic liquid (1-butyl-3-methylimidazolium chloride, manufactured by Aldrich) vacuum-dried at 90 ° C. for 12 hours (About 750, about 3 mm square sheet form) 5 parts by weight was added and stirred at 80 ° C. for 2 hours in a nitrogen atmosphere to dissolve the cellulose in the ionic liquid. As an acylating agent, 3.6 equivalents of acetic anhydride was added and stirred at 60 ° C. for 2 hours under a nitrogen atmosphere. Then, the reaction liquid was thrown into 1500 weight part of water, and the cellulose acetate (CE-5) was deposited. The precipitated CE-5 was separated by filtration, washed with water using 100 parts by weight of water and separated by filtration three times, and then vacuum-dried at 80 ° C. for 4 hours.

  For the obtained CE-5, the acyl group substitution degree, the half width of the peak in the composition distribution of the acyl group substitution degree, and the ratio of cellulose acylate contained in the half width in the composition distribution were measured. The results are shown in Table 1 below.

(Production Example 6: Production of CE-6)
Cellulose vacuum-dried at 90 ° C. for 12 hours to 100 parts by weight of ionic liquid (1-butyl-3-methylimidazolium chloride, manufactured by Aldrich) vacuum-dried at 90 ° C. for 12 hours (dissolved pulp manufactured by Nippon Paper Industries Co. Ltd. (About 750, about 3 mm square sheet form) 5 parts by weight was added and stirred at 80 ° C. for 2 hours in a nitrogen atmosphere to dissolve the cellulose in the ionic liquid. As an acylating agent, 3.6 equivalents of acetic anhydride was added and stirred at 80 ° C. for 2 hours under a nitrogen atmosphere. Then, the reaction liquid was thrown into 1500 weight part of water, and the cellulose acetate (CE-6) was deposited. The precipitated CE-6 was separated by filtration, washed with 100 parts by weight of water and filtered three times, and then vacuum-dried at 80 ° C. for 4 hours.

  For the obtained CE-6, the acyl group substitution degree, the half width of the peak in the composition distribution of the acyl group substitution degree, and the ratio of cellulose acylate contained in the half width in the composition distribution were measured. The results are shown in Table 1 below.

(Production Example 7: Production of CE-7)
Cellulose (dissolved pulp manufactured by Nippon Paper Industries Co., Ltd., degree of polymerization) vacuum-dried at 90 ° C. for 12 hours to 100 parts by weight of ionic liquid (1-butyl-3-methylimidazolium chloride, manufactured by Aldrich) vacuum-dried at 90 ° C. for 12 hours (About 750, about 3 mm square sheet form) 5 parts by weight was added, and the mixture was stirred at 80 ° C. for 0.5 hours in a nitrogen atmosphere to dissolve the cellulose in the ionic liquid. After adding 1.8 equivalents of propionic anhydride as the acylating agent 1 and stirring at 80 ° C. for 0.25 hours under a nitrogen atmosphere, 1.8 equivalents of acetic anhydride as the acylating agent 2 was added, and 80 ° C. under a nitrogen atmosphere. For 0.25 hours. Thereafter, the reaction solution was added to 1500 parts by weight of water to precipitate cellulose acetate propionate (CE-7). The precipitated CE-7 was filtered off, washed with 100 parts by weight of water and filtered three times, and then vacuum dried at 80 ° C. for 4 hours.

  For the obtained CE-7, the acyl group substitution degree, the half width of the peak in the composition distribution of the acyl group substitution degree, and the ratio of cellulose acylate contained in the half width in the composition distribution were measured. The results are shown in Table 1 below.

(Production Example 8: Production of CE-8)
Cellulose vacuum-dried at 90 ° C for 12 hours to 100 parts by weight of ionic liquid (1-butyl-3-methylimidazolium acetate, manufactured by Aldrich) vacuum-dried at 90 ° C for 12 hours (dissolved pulp manufactured by Nippon Paper Industries Co., Ltd., degree of polymerization) 5 parts by weight (about 750, about 3 mm square sheet form) were added, and the mixture was stirred at 40 ° C. for 2 hours under a nitrogen atmosphere to dissolve the cellulose in the ionic liquid. After adding 1.8 equivalents of propionic anhydride as acylating agent 1 and stirring at 40 ° C. for 1 hour under nitrogen atmosphere, 1.8 equivalents of acetic anhydride as acylating agent 2 and adding 1 equivalent at 40 ° C. under nitrogen atmosphere. Stir for hours. Thereafter, the reaction solution was added to 1500 parts by weight of water to precipitate cellulose acetate propionate (CE-8). The precipitated (CE-8) was separated by filtration, washed with 100 parts by weight of water and separated by filtration three times, and then vacuum-dried at 80 ° C. for 4 hours.

  For the obtained CE-8, the acyl group substitution degree, the half width of the peak in the composition distribution of the acyl group substitution degree, and the ratio of cellulose acylate contained in the half width in the composition distribution were measured. The results are shown in Table 1 below.

(Production Example 9: Production of CE-9)
Cellulose (dissolved pulp manufactured by Nippon Paper Industries Co., Ltd., degree of polymerization) vacuum-dried at 90 ° C. for 12 hours to 100 parts by weight of ionic liquid (1-butyl-3-methylimidazolium chloride, manufactured by Aldrich) vacuum-dried at 90 ° C. for 12 hours (About 750, about 3 mm square sheet form) 5 parts by weight was added and stirred at 80 ° C. for 2 hours in a nitrogen atmosphere to dissolve the cellulose in the ionic liquid. After adding 1.5 equivalents of propionic anhydride as acylating agent 1 and stirring at 80 ° C. for 1 hour in a nitrogen atmosphere, 1.1 equivalents of acetic anhydride is added as acylating agent 2 and 1 at 80 ° C. in a nitrogen atmosphere. Stir for hours. Then, the reaction liquid was thrown into 1500 weight part of water, and the cellulose acetate propionate (CE-9) was deposited. The precipitated CE-9 was separated by filtration, washed with 100 parts by weight of water and filtered three times, and then vacuum-dried at 80 ° C. for 4 hours.

  For the obtained CE-9, the acyl group substitution degree, the half width of the peak in the composition distribution of the acyl group substitution degree, and the ratio of cellulose acylate contained in the half width in the composition distribution were measured. The results are shown in Table 1 below.

(Production Example 10: Production of CE-10)
Cellulose (dissolved pulp manufactured by Nippon Paper Industries Co., Ltd., degree of polymerization) vacuum-dried at 90 ° C. for 12 hours to 100 parts by weight of ionic liquid (1-butyl-3-methylimidazolium chloride, manufactured by Aldrich) vacuum-dried at 90 ° C. for 12 hours (About 750, about 3 mm square sheet form) 5 parts by weight was added and stirred at 80 ° C. for 2 hours in a nitrogen atmosphere to dissolve the cellulose in the ionic liquid. Add 1.6 equivalents of butyric anhydride as acylating agent 1 and stir at 80 ° C. for 1 hour in a nitrogen atmosphere, then add 1.9 equivalents of acetic anhydride as acylating agent 2 and 1 hour at 80 ° C. in a nitrogen atmosphere. Stir. Thereafter, the reaction solution was added to 1500 parts by weight of water to precipitate cellulose acetate butyrate (CE-10). The precipitated CE-10 was separated by filtration, washed with 100 parts by weight of water and filtered three times, and then vacuum-dried at 80 ° C. for 4 hours.

  For the obtained CE-10, the acyl group substitution degree, the half width of the peak in the composition distribution of the acyl group substitution degree, and the ratio of cellulose acylate contained in the half width in the composition distribution were measured. The results are shown in Table 1 below.

(Production Example 11: Production of CE-11)
Cellulose (dissolved pulp manufactured by Nippon Paper Industries Co., Ltd., degree of polymerization) vacuum-dried at 90 ° C. for 12 hours to 100 parts by weight of ionic liquid (1-ethyl-3-methylimidazolium acetate, manufactured by Aldrich) vacuum-dried at 90 ° C. for 12 hours (About 750, about 3 mm square sheet form) 5 parts by weight was added and stirred at 80 ° C. for 2 hours in a nitrogen atmosphere to dissolve the cellulose in the ionic liquid. After adding 1.8 equivalents of propionic anhydride as acylating agent 1 and stirring at 80 ° C. for 1 hour under nitrogen atmosphere, 1.8 equivalents of acetic anhydride as acylating agent 2 and adding 1 equivalent at 40 ° C. under nitrogen atmosphere. Stir for hours. Then, the reaction liquid was thrown into 1500 weight part of water, and the cellulose acetate propionate (CE-11) was deposited. Precipitated (CE-11) was separated by filtration, washed with water using 100 parts by weight of water and separated by filtration three times, and then vacuum-dried at 80 ° C. for 4 hours.

  For the obtained CE-11, the acyl group substitution degree, the half width of the peak in the composition distribution of the acyl group substitution degree, and the ratio of cellulose acylate contained in the half width in the composition distribution were measured. The results are shown in Table 1 below.

  (Preparation of CE-12) What purchased the commercially available cellulose acetate propionate was used as CE-12. For this CE-12, the acyl group substitution degree, the half width of the peak in the composition distribution of the acyl group substitution degree, and the ratio of cellulose acylate contained in the half width in the composition distribution were measured. The results are shown in Table 1 below.

≪Example of retardation film production≫
(Structure of retardation adjusting agent)
In the following retardation film production examples, the compounds used as the retardation adjusting agent are as follows.

(Preparation of retardation film 101)
<Fine particle dispersion 1>
Fine particles (Aerosil R812 manufactured by Nippon Aerosil Co., Ltd.) 11 parts by weight Ethanol 89 parts by weight The above was stirred and mixed with a dissolver for 50 minutes, and then dispersed with Manton Gorin.

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

Methylene chloride 99 parts by mass Fine particle dispersion 1 5 parts by mass A main dope solution having the following composition was prepared. First, methylene chloride and ethanol were added as solvents to the pressure dissolution tank. The CE-1 produced above was added to a pressurized dissolution tank containing a solvent while stirring. This is completely dissolved with heating and stirring. This was designated as Azumi Filter Paper No. The main dope solution was prepared by filtration using 244.

<Composition of main dope solution>
Methylene chloride 340 parts by mass Ethanol 64 parts by mass Cellulose acylate (CE-1) 100 parts by mass Sugar ester compound (FA-6) 10 parts by mass Retardation adjuster (compound a) 4 parts by mass Fine particle additive solution 1 1 part by mass or more Was put into a sealed main dissolution vessel and dissolved with stirring to prepare a dope solution.

  On the stainless steel belt support, the solvent was evaporated until the residual solvent amount in the cast (cast) film was 75%, and then peeled off from the stainless steel belt support with a peeling tension of 130 N / m. The peeled film was stretched 46% in the width direction using a tenter while applying heat at 170 ° C. to make the film width 2.45 m. The residual solvent at the start of stretching was 15%.

  Next, drying was terminated while the drying zone was conveyed by a number of rolls. The drying temperature was 130 ° C. and the transport tension was 100 N / m.

  As described above, a retardation film 101 having a film thickness of 35 μm after drying was obtained. About the obtained retardation film, Ro and Rth and the internal haze were measured, respectively. The results are shown in Table 2 below.

(Production of retardation films 102 to 115)
Table 2 below shows the types of cellulose acylate, the types and addition amounts of sugar ester compounds, the types and addition amounts of retardation modifiers, the draw ratio, the film width after stretching, and the film thickness after drying. Except for this, the retardation films 102 to 115 were produced by the same method as the production of the retardation film 101 described above.

  About each obtained retardation film, Ro and Rth and the internal haze were measured, respectively. The results are shown in Table 2 below.

  As shown in Table 2, it can be seen that according to the present invention, a retardation film having small internal haze and high transparency can be provided.

(Preparation of retardation film 201)
<Fine particle dispersion 1>
Fine particles (Aerosil R812 manufactured by Nippon Aerosil Co., Ltd.) 11 parts by weight Ethanol 89 parts by weight The above was stirred and mixed with a dissolver for 50 minutes, and then dispersed with Manton Gorin.

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

Methylene chloride 99 parts by mass Fine particle dispersion 1 5 parts by mass A main dope solution having the following composition was prepared. First, methylene chloride and ethanol were added as solvents to the pressure dissolution tank. The CE-1 produced above was added to a pressurized dissolution tank containing a solvent while stirring. This is completely dissolved with heating and stirring. This was designated as Azumi Filter Paper No. The main dope solution was prepared by filtration using 244.

<Composition of main dope solution>
Methylene chloride 340 parts by mass Ethanol 64 parts by mass Cellulose acylate (CE-1) 100 parts by mass Sugar ester compound (FA-2) 10 parts by mass Retardation adjuster (compound c) 8 parts by mass Fine particle additive solution 1 1 part by mass or more Was put into a sealed main dissolution vessel and dissolved with stirring to prepare a dope solution.

  Next, using an endless belt casting apparatus, the dope solution was cast on a stainless steel belt support at a temperature of 33 ° C. and a width of 1500 mm. The temperature of the stainless steel belt was controlled at 30 ° C.

  On the stainless steel belt support, the solvent was evaporated until the residual solvent amount in the cast (cast) film became 75%, and then peeled off from the stainless steel belt support with a peeling tension of 110 N / m. The peeled cellulose ester film was stretched 5% in the width direction using a tenter while applying heat at 160 ° C. The residual solvent at the start of stretching was 15%.

  Next, drying was terminated while transporting the drying zone with a number of rolls, and the ends sandwiched between tenter clips were slit with a laser cutter, and then wound. The drying temperature was 130 ° C. and the transport tension was 100 N / m.

  The roll-shaped long film original 1 was set in a slidable feeding device shown in FIG. 1 and supplied to an obliquely stretched tenter in which a rail pattern was set so that the angle θi = 47 °. In addition, as a zone combination of the oblique stretching tenter at this time, a combination including a preheating zone, a lateral stretching zone, an oblique stretching zone, a holding zone, and a cooling zone was used. At that time, the distance between the main axis of the guide roll closest to the inlet portion of the obliquely stretched tenter and the gripping tool (clip gripping portion) of the obliquely stretched tenter was 80 cm. A clip with a length of 2 inches in the conveying direction was used, and a guide roll with a diameter of 10 cm was used. In the oblique stretching tenter, the temperature of the preheating zone was 180 ° C., the temperature of the transverse stretching zone was 177 ° C., the temperature of the oblique stretching zone was 177 ° C., the temperature of the holding zone was 177 ° C., and the temperature of the cooling zone was 110 ° C. . The take-up tension at the tenter outlet was 200 N / m.

  Drawing was performed so that the draw ratio at this time was 1.95. As a breakdown of the draw ratio R at this time, the film was stretched to 1.3 times in the transverse stretching zone and 1.5 times in the oblique stretching zone.

  At this time, the film was stretched in an oblique direction so that the orientation angle θ was 45 °. The stretched film was controlled so that the fluctuation in the take-up tension was less than 3% by performing feedback control in which the change in the tension measured with the first roll on the outlet side of the obliquely stretched tenter was reflected in the take-up motor rotation speed. Then, both ends of the film are trimmed, the conveyance direction is changed by a conveyance direction changing device composed of an airflow roll, the film is wound by a slidable winding device, the film width is 2000 mm, and the film thickness after drying is a 40 μm film thickness 201 was obtained. About the obtained retardation film, Ro and Rth and the internal haze were measured, respectively. The results are shown in Table 3 below.

(Production of retardation films 202 and 204 to 214)
The above except that the type of cellulose acylate, the type and addition amount of the sugar ester compound, the type and addition amount of the retardation modifier, the draw ratio, and the film thickness after drying were changed as shown in Table 3 below. The retardation films 202 and 204 to 214 were manufactured by the same method as that for manufacturing the retardation film 201.

  About each obtained retardation film, Ro and Rth and the internal haze were measured, respectively. The results are shown in Table 3 below.

(Preparation of retardation film 203)
The type of cellulose acylate, the type and addition amount of the sugar ester compound, the type and addition amount of the retardation adjusting agent, and the film thickness after drying are changed as shown in Table 3 below, and MD is not diagonally stretched. A retardation film 203 was produced by the same method as the production of the retardation film 201 described above except that the film was stretched in the direction at a stretching ratio of 45%.

  About the obtained retardation film 203, Ro and Rth and the internal haze were measured, respectively. The results are shown in Table 3 below.

  As shown in Table 3, it can be seen that according to the present invention, a retardation film having low internal haze and high transparency can be provided.

≪Example of polarizing plate production≫
(Preparation of polarizing plates 101-115)
A 120 μm-thick polyvinyl alcohol film was uniaxially stretched (temperature: 110 ° C., stretch ratio: 5 times).

  This was immersed in an aqueous solution composed of 0.075 g of iodine, 5 g of potassium iodide and 100 g of water for 60 seconds, and then immersed in an aqueous solution of 68 ° C. composed of 6 g of potassium iodide, 7.5 g of boric acid and 100 g of water. This was washed with water and dried to obtain a polarizer.

  Next, the polarizer, the retardation films 101 to 115 produced above according to the following steps 1 to 5, and Konica Minolta Tack KC4UA (Konica Minolta Opto's cellulose ester film, thickness 40 μm) are bonded to the back side. Thus, polarizing plates 101 to 115 were produced.

  Process 1: Retardation films 101-115 and Konica Minoltack KC4UA which were immersed in a 2 mol / L sodium hydroxide solution at 60 ° C. for 90 seconds, then washed with water and dried to saponify the side to be bonded to the polarizer Got.

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

  Step 3: Excess adhesive adhered to the polarizer in Step 2 was gently wiped off, and this was placed on the retardation films 101 to 115 processed in Step 1.

Step 4: The retardation films 101 to 115 laminated in Step 3 and the polarizer and the back side Konica Minolta Tack KC4UA were bonded at a pressure of 20 to 30 N / cm ² and a conveyance speed of about 2 m / min.

  Process 5: The sample which bonded the polarizer produced in process 4, the phase difference films 101-115, and Konica Minoltack KC4UA in the dryer of 80 degreeC for 2 minutes is dried, and each is made into phase difference films 101-115, respectively. Corresponding polarizing plates 101 to 115 were produced.

(Preparation of polarizing plates 201-214)
Instead of the configuration in which the polarizer is sandwiched between the retardation film manufactured above and Konica Minolta KC4UA, each of the two retardation films 201 to 214 manufactured above is used to sandwich the polarizer. Except for this, polarizing plates 201 to 214 corresponding to the retardation films 201 to 214 were produced by the same method as described above.

≪Evaluation as a liquid crystal display device≫
(Production of liquid crystal display device)
A liquid crystal panel for viewing angle measurement was produced as follows, and the characteristics as a liquid crystal display device were evaluated. The configuration of the display device and the evaluation results are shown in Table 4 below.

  The polarizing plates on both sides of the SONY 40-type display BRAVIA X1 that had been bonded in advance were peeled off, and any of the retardation films 101 to 115 manufactured above was bonded to both surfaces of the glass surface of the liquid crystal cell.

  At that time, the direction of bonding of the polarizing plate is such that the surfaces of the retardation films 101 to 115 are on the liquid crystal cell side, and the absorption axis is in the same direction as the polarizing plate bonded in advance. Thus, liquid crystal display devices 301 to 315 corresponding to the polarizing plates 101 to 115 were produced, respectively.

(Evaluation of front contrast unevenness)
The front contrast was measured for the liquid crystal display device produced above. Specifically, the backlight of each liquid crystal display device was lit continuously for 1 week in an environment of 60 ° C. and 80% RH, and then left in a room at 25 ° C. and 60% RH for 2 hours for measurement. For measurement, EZ-Contrast 160D manufactured by ELDIM was used, the luminance from the normal direction of the display screen of white display and black display was measured with a liquid crystal display device, and the ratio (calculated by the following formula) was defined as the front contrast.

  The front contrast at any five points of the liquid crystal display device was measured and evaluated according to the following criteria.

◎: Front contrast is 0 to less than 5% variation and unevenness is small ○: Front contrast is less than 5 to 10% variation and slightly uneven Δ: Front contrast is less than 10 to 20% variation Yes, slightly uneven ×: Front contrast is more than 20%, and unevenness is very large (Evaluation of viewing angle characteristics)
About each liquid crystal display device produced above, viewing angle characteristics were evaluated. Specifically, each liquid crystal display device was stored for 48 hours in an environment of 23 ° C. and 95% RH. For the liquid crystal display device after storage, the backlight was lit continuously for 1 hour in an environment of 23 ° C. and 55% RH, and then the contrast at 60 ° oblique direction with respect to the normal direction of the display screen was measured. At this time, the 60 ° diagonal contrast was measured according to the following procedure, and the 60 ° diagonal contrast was calculated according to the following formula.

  i) Luminance in a 60 ° oblique direction (luminance measured at an angle of 60 ° with respect to the normal direction of the display screen) when the liquid crystal display device displays white is measured by EZ-Contrast 160D manufactured by ELDIM It was measured. Similarly, the luminance in a 60 ° oblique direction of the display screen when the liquid crystal display device was displayed in black was measured.

  ii) The ratio of the 60 ° oblique luminance of the display screen when white is displayed to the 60 ° oblique luminance of the display screen when black is indicated as “60 ° diagonal contrast”.

  Viewing angle characteristics based on contrast in a 60 ° oblique direction were evaluated according to the following criteria.

◎: 60 ° oblique contrast is 100 or more ○: 60 ° oblique contrast is 90 or more and less than 100 △: 60 ° oblique contrast is 80 or more and less than 90 ×: 60 ° oblique contrast is less than 80

  As shown in Table 4, when the retardation film provided by the present invention is used in a liquid crystal display device as a viewing angle widening (optical compensation) film having a function of a polarizing plate protective film, front contrast unevenness, visual field It can be seen that a liquid crystal display device having excellent angular characteristics can be realized.

<Production of organic EL display device>
Samsung's galaxy-s touch panel and polarizing plate were removed, and any one of the polarizing plates 201 to 214 produced above was bonded to produce corresponding organic EL display devices 401 to 414.

  With respect to the obtained organic EL display devices 401 to 414, front contrast unevenness and viewing angle characteristics were evaluated by the same method as described above. The results are shown in Table 5 below.

  As shown in Table 5, even when the retardation film provided by the present invention is used as an antireflection film for an organic EL display device, the organic EL display is excellent in both front contrast unevenness and viewing angle characteristics. It can be seen that the device is feasible.

4 Long film stock,
5 long stretched film,
6 Obliquely stretched tenter,
7-1 Trajectory of the outer film gripping means,
7-2 Trajectory of inner film gripping means,
8-1 Outer film grip start point,
8-2 Inner film grip start point,
9-1 Outer film grip end point,
9-2 Inner film grip end point,
10-1 Outer oblique stretching start point,
10-2 Starting point of inner diagonal stretching,
11-1 End point of outer diagonal stretching,
11-2 End point of inner diagonal stretching,
12-1 Guide roll on the tenter entrance side,
12-2 Guide roll on the tenter exit side,
13 Stretch direction of the film,
14-1 Transport direction of the film before oblique stretching,
14-2 Film transport direction after oblique stretching,
W ₀ film width before oblique stretching,
W The width of the film after oblique stretching.

Claims (9)

A retardation film containing cellulose acylate,
The acyl substitution degree of the cellulose acylate is 1.9 to 2.5, the half width of the peak in the composition distribution measured by HPLC of the acyl substitution degree is 0.15 or less in substitution degree units, A retardation film in which a ratio of cellulose acylate included in the half width in the composition distribution is 65% or more. The following general formula (I):
In the formula, Q represents a monosaccharide or disaccharide residue, R represents an aliphatic group or an aromatic group, and m represents the number of hydroxyl groups directly bonded to the monosaccharide or disaccharide residue. L is the sum of the number of — (O—C (═O) —R) groups directly attached to the monosaccharide or disaccharide residue, and 3 ≦ m + l ≦ 8, l ≠ 0,
The retardation film of Claim 1 containing the sugar ester compound represented by these. The following formula (1) and the following formula (2):
(In the formula, nx represents the refractive index in the slow axis direction in the film plane, ny represents the refractive index in the fast axis direction in the film plane, nz represents the refractive index in the film thickness direction, and d represents the film. The refractive index is measured at a wavelength of 590 nm in an environment of 25 ° C. and 55% RH)
And Ro and Rth respectively represented by
The retardation film according to claim 1, wherein the retardation film satisfies the following. The following mathematical formula (1):
In the formula, nx represents the refractive index in the slow axis direction in the film plane, ny represents the refractive index in the fast axis direction in the film plane, d represents the thickness (nm) of the film; (Measured at a wavelength of 590 nm in an environment of ℃ 55% RH)
Ro represented by
The retardation film according to claim 1, wherein the retardation film satisfies the following. Reacting cellulose with an acylating agent in the presence of an ionic liquid to obtain a cellulose acylate having an acyl group substitution degree of 1.9 to 2.5;
The film obtained by pouring the dope containing the cellulose acylate onto a support is dried and peeled, and then stretched at least in the width direction at a stretch ratio of 1.1 times or more to obtain a film width of 1.8 to 2. Obtaining a 5 m retardation film;
A method for producing a retardation film. Reacting cellulose with an acylating agent in the presence of an ionic liquid to obtain a cellulose acylate having an acyl group substitution degree of 1.9 to 2.5;
Drying the film obtained by pouring the dope containing the cellulose acylate on a support, peeling, and then performing oblique stretching to obtain a retardation film; and
A method for producing a retardation film.   The retardation film of any one of Claims 1-4 or the retardation film manufactured by the manufacturing method of Claim 5 or 6, and at least one surface of a polarizer are bonded. ,Polarizer.   A polarizing plate comprising the retardation film according to any one of claims 1 to 3 or the retardation film produced by the production method according to claim 5 and at least one surface of a polarizer. A liquid crystal display device.   A retardation film produced by the retardation film according to claim 1, 2 or 4 or the retardation film produced by the production method according to claim 6, and a polarizing plate comprising at least one surface of a polarizer are provided. Organic EL display device.