JP5500042B2 - Method for producing cellulose ester - Google Patents

Description

The present invention relates to the production how very little cellulose ester content of the gel-like foreign matter.

  Cellulose acetate films are used as films in various photographic materials and optical materials because of their toughness and flame retardancy. For example, a cellulose acetate film is a typical support for photographic light-sensitive materials. Cellulose acetate films are also used in liquid crystal display devices because of their optical isotropy.

  Since such an optical film of cellulose acetate is optically used, it is required that there are few optical defects that affect light transmission. And if it is the use of the conventional optical film, even if it is a fine surface unevenness | corrugation, foreign material, or an optical defect which does not have a quality problem, it will become a problem in an optical film. In particular, when an optical film is used as a component of a liquid crystal display device, a so-called bright spot foreign substance or gel-like foreign substance that abnormally refracts transmitted light even if it is transparent becomes an optical defect and the quality. It becomes the problem above.

  In recent years, these liquid crystal display devices are used not only as display devices for personal computers but also as display devices for television receivers, DVDs, etc., or display devices for mobile phones and PDAs (mobile terminals). There are demands for fewer defects. That is, in recent years, display devices for personal computers, television receivers, and computer games have become larger and larger, and the number of image forming elements (so-called dot numbers) has increased as symbolized by full high-definition LCD televisions. The area of the area per image forming element has become very small.

  With such technological trends, performance and properties required for polarizer protective films, antireflection film optical films, and stretched optical films used in liquid crystal display devices are diversifying. For one thing, there is a need to provide films with fewer optical defects per unit area.

  These foreign substances include black foreign substances, bright spot foreign substances, and gel-like foreign substances. Black foreign matters are caused by impurities, deteriorated materials, and the like, and bright spot foreign matters are mainly caused by cellulose ester or the like that is close to non-acetylated, and are produced by abnormal refraction of transmitted light with different refractive indexes. On the other hand, unlike the above two foreign substances, the gel-like foreign substance is a foreign substance in which the detailed chemical structure and generation mechanism are not clarified and the amount present in the film is large.

  In Patent Document 1, as a method for reducing the bright spot foreign matter, a method is proposed in which the cellulose ester solution is filtered and then diffused and dried. Moreover, in patent document 2, in the process of acylating cellulose, after acylating with an excess acid anhydride, it mixes the stop agent containing water within the temperature range of -30-30 degreeC, and it is a fine foreign material. A method for reducing the above has been proposed. However, most of the bright spot foreign matter can be reduced by the above method, and the reduction effect of the gel-like foreign matter is not satisfactory.

  On the other hand, Patent Document 3 proposes a method of reducing bright spot foreign matter by controlling the temperature of the manufacturing process and performing microfiltration. Patent Document 4 proposes a method in which Celite is mixed in a cellulose ester solution and fine foreign substances are reduced by filtration. Although this method can reduce bright spot foreign matter and gel-like foreign matter, the effect of reducing gel-like foreign matter is not sufficient, and improvement has been demanded.

JP 2008-56819 A JP 2007-138141 A JP 2008-127535 A JP 2008-31396 A

The present invention has been made in view of the above problems or situation, the problem to be solved is to provide a manufacturing how very little cellulose ester content of the gel-like foreign matter.

  The above-mentioned problem according to the present invention is solved by the following means.

1. A cellulose ester production method comprising a step of precipitating cellulose ester by mixing a cellulose ester solution and a poor solvent, wherein the SP value of the whole poor solvent is 30.0 to 40.0 (MPa) ^1/2 The SP value of the poor solvent is 45.0 (MPa) ^1/2 or less, and the mass of the poor solvent is 0.5 to 10.0 times the mass of the cellulose ester solution. range der of is, contains further the cellulose ester solution or alcohols at least one of the poor solvent, the mass of the alcohol is 0.5 to 10 times the weight of the cellulose ester The manufacturing method of the cellulose ester characterized by being in the inside .

2. The SP value of the solvent in the cellulose ester solution is in the range of 18.5 to 29.0 (MPa) ^1/2 , and the SP value of the solvent after mixing the cellulose ester solution and the poor solvent is 28. It is in the range of 0-40.0 (MPa) < ^1/2 >, The manufacturing method of the cellulose ester of said 1st term | claim characterized by the above-mentioned.

  3. The method for producing a cellulose ester according to item 1 or 2, wherein the mass of the poor solvent is in a range of 1.0 to 5.0 times the mass of the cellulose ester solution.

By the means of the present invention, it is possible to provide a manufacturing how very little cellulose ester content of the gel-like foreign matter.

  As a result of intensive studies on the above problems, the present inventors have found that the main component of the gel-like foreign material is a cellulose ester having a very low degree of substitution. These components having a very low degree of substitution are considered to be generated in the production process, but it was difficult to remove them only by the filtration and precipitation steps performed in the conventional optical film production process.

In the present invention, as a method for removing or dispersing the cellulose ester component having a very low degree of substitution, the SP value of the entire poor solvent is 30.0 to 3 in the step of mixing the cellulose ester solution and the poor solvent to precipitate the cellulose ester. The maximum value of the SP value of the poor solvent to be mixed is 45.0 (MPa) ^1/2 or less within the range of 40.0 (MPa) ^1/2 , and the mass of the whole poor solvent used is cellulose. It has been found that it is effective to make the mass within the range of 0.5 to 10.0 times the mass of the ester solution, and by using this production method, it has been found that a cellulose ester in which gel-like foreign matters are remarkably reduced can be obtained.

This is because the cellulose ester solution and the poor solvent so that precipitation of the cellulose ester occurs when the total mass of the poor solvent used is within the range of 0.5 to 10.0 times the mass of the cellulose ester solution. By adjusting the composition, the precipitation step can be performed in a state where the gel-like foreign matter is sufficiently dissolved, and the SP value of the entire poor solvent is in the range of 30.0 to 40.0 (MPa) ^1/2 . In addition, by setting the maximum SP value of the poor solvent to be mixed to 45.0 (MPa) ^1/2 or less, precipitation of gel-like foreign matters is suppressed when mixed with the poor solvent, and the cellulose ester is precipitated. It is considered that there is an effect of suppressing the incorporation of gel-like foreign matters when

  Further, by containing an alcohol in at least one of the cellulose ester solution or the poor solvent, dissolution or dispersion of the gel-like foreign matter is promoted, aggregation of the cellulose ester is suppressed, and dispersion stability of the cellulose ester solution is increased. Therefore, the cellulose ester in which the content of the gel-like foreign material is significantly reduced can be obtained as a powder. Moreover, the optical film excellent in the optical characteristic is obtained by using the cellulose ester which the gel-like foreign material reduced remarkably.

  The term “gel-like foreign material” as used herein means that two polarizing plates are placed in a crossed Nicols state, an optical film or the like is placed between them, light is applied from the side of one polarizing plate, and the other polarizing light is applied. Although light from the opposite side does not leak when observed from the side of the plate, it is a foreign material that is observed as irregularities on the film surface and is indefinite when viewed with a transmission microscope.

  On the other hand, “bright spot foreign matter” as used herein means that two polarizing plates are placed in a crossed Nicols state, an optical film or the like is placed between them, light is applied from the side of one polarizing plate, and the other polarizing light is applied. It is the point (foreign matter) that light from the opposite side appears to leak when observed from the side of the plate.

The method for producing a cellulose ester of the present invention is a method for producing a cellulose ester having a step of precipitating a cellulose ester by mixing a cellulose ester solution and a poor solvent, and the SP value of the whole poor solvent is 30.0 to 40.0 (MPa) ^1/2 , and the maximum SP value of the poor solvent is 45.0 (MPa) ^1/2 or less, and the mass of the poor solvent is that of the cellulose ester solution. Ri range der of 0.5 to 10.0 times the mass, further includes alcohols to at least one of the cellulose ester solution or the poor solvent, the mass of the alcohol is, the weight of the cellulose ester On the other hand, it is in the range of 0.5 to 10 times . This feature is a technical feature common to the inventions according to claims 1 to 3 .

As an embodiment of the present invention, from the viewpoint of expression of the effect of the present invention, the SP value of the solvent in the cellulose ester solution is in the range of 18.5 to 29.0 (MPa) ^1/2 and the cellulose ester The SP value of the solvent after mixing the solution and the poor solvent is preferably in the range of 28.0 to 40.0 (MPa) ^1/2 . Furthermore, the mass of the poor solvent is preferably in the range of 1.0 to 5.0 times the mass of the cellulose ester solution.

  The cellulose ester produced by the method for producing a cellulose ester of the present invention preferably simultaneously satisfies the substitution degree within the range represented by the formulas (1) and (2).

  The cellulose ester can be suitably used for an optical film. Furthermore, the optical film can be suitably used for polarizing plates and liquid crystal display devices.

  Hereinafter, the present invention, its components, and modes and modes for carrying out the present invention will be described in detail. In addition, in this application, "-" is used in the meaning which includes the numerical value described before and behind that as a lower limit and an upper limit.

<Cellulose ester>
The cellulose ester according to the present invention is preferably used for optical film applications, preferably the total acyl substitution degree of the cellulose ester is in the range of 2.0 to 2.95 and the total acyl group carbon number is 4. It is a cellulose ester within the range of 0.0 to 9.5. However, the acyl group total carbon number is the sum total of the products of the substitution degree and the carbon number of each acyl group substituted in the glucose unit of the cellulose ester.

  Furthermore, the number of carbon atoms of the aliphatic acyl group is preferably 2 or more and 6 or less, and more preferably 2 or more and 4 or less, from the viewpoint of productivity and cost of cellulose synthesis. The portion not substituted with an acyl group usually exists as a hydroxyl group (hydroxyl group).

  Glucose units constituting cellulose with β-1,4-glycosidic bonds have free hydroxyl groups (hydroxyl groups) at the 2nd, 3rd and 6th positions. The cellulose ester in the present invention is a polymer obtained by esterifying some or all of these hydroxyl groups (hydroxyl groups) with an acyl group. The acyl group substitution degree represents the total of the proportions of cellulose esterified at the 2nd, 3rd and 6th positions of the repeating unit. Specifically, the degree of substitution is 1 when each of the hydroxyl groups (hydroxyl groups) at the 2nd, 3rd and 6th positions of cellulose is 100% esterified. Therefore, when all of the 2nd, 3rd and 6th positions of cellulose are 100% esterified, the degree of substitution is 3 at the maximum.

  Examples of the acyl group include an acetyl group, a propionyl group, a butyryl group, a pentanate group, and a hexanate group. Examples of the cellulose ester include cellulose acetate, cellulose propionate, cellulose butyrate, and cellulose pentanate. . Further, mixed fatty acid esters such as cellulose acetate, cellulose acetate propionate, cellulose propionate, cellulose acetate butyrate, and cellulose acetate pentanate may be used as long as the above-mentioned side chain carbon number is satisfied. Among these, cellulose acetate, cellulose acetate propionate, and cellulose propionate are particularly preferable cellulose esters for optical film applications.

  Preferred cellulose esters other than cellulose triacetate have an acyl group having 2 to 4 carbon atoms as a substituent, and when the substitution degree of acetyl group is X and the substitution degree of propionyl group or butyryl group is Y, the following formula ( It is a cellulose ester containing the cellulose ester which satisfy | fills I) and (II) simultaneously.

Formula (I) 2.0 ≦ X + Y ≦ 2.95
Formula (II) 0 ≦ X ≦ 2.5
Among these, cellulose acetate propionate is particularly preferably used, and it is particularly preferable that 2.0 ≦ X + Y ≦ 2.9 and 0.5 ≦ Y ≦ 2.7. The portion not substituted with an acyl group usually exists as a hydroxyl group (hydroxyl group). The measuring method of acyl group substitution degree can be measured according to ASTM-D817-96.

  The cellulose ester according to the present invention preferably has a weight average molecular weight Mw of 50,000 to 500,000, more preferably 100,000 to 300,000, still more preferably 150,000 to 250,000. .

  Since the average molecular weight and molecular weight distribution of a cellulose ester can be measured using high performance liquid chromatography, the weight average molecular weight (Mw) and molecular weight distribution are calculated using this.

  The measurement conditions are as follows.

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

  The cellulose ester raw material cellulose used in the present invention may be wood pulp or cotton linter, and the wood pulp may be softwood or hardwood. The cellulose ester made from these can be mixed suitably or can be used independently.

  For example, the ratio of cellulose ester derived from cellulose linter: cellulose ester derived from wood pulp (coniferous): cellulose ester derived from wood pulp (hardwood) is 100: 0: 0, 90: 10: 0, 85: 15: 0, 50:50: 0, 20: 80: 0, 10: 90: 0, 0: 100: 0, 0: 0: 100, 80:10:10, 85: 0: 15, 40:30:30.

  In the present invention, cellulose having a high degree of polymerization is preferable, for example, linter pulp is preferable, and it is preferable to use cellulose composed of at least linter pulp. The α-cellulose content that is an index of the crystallinity of cellulose is 90% or more (for example, about 92 to 100%, preferably 95 to 100%, and more preferably about 99.5 to 100%).

<Cellulose ester solution>
The manufacturing method of the cellulose ester of this invention has a process which mixes a cellulose-ester solution and a poor solvent, and precipitates a cellulose ester. Moreover, the SP value of the whole poor solvent is in the range of 30.0 to 40.0 (MPa) ^1/2 and the maximum value of the SP value of the poor solvent is 45.0 (MPa) ^1/2 or less. , and the Ri range der of 0.5 to 10.0 times the mass of the mass of the poor solvent of the cellulose ester solution, contains further the cellulose ester solution or alcohols at least one of the poor solvent And the mass of the alcohol is in the range of 0.5 to 10 times the mass of the cellulose ester .

  Here, the “SP value of the entire poor solvent” is a value obtained by multiplying the mass% of the used poor solvent with respect to the entire poor solvent by the SP value of the poor solvent and totaling the total amount of the used poor solvent. It is called the total SP value. The whole poor solvent is a solvent in which all the poor solvents used for precipitating the cellulose ester from the cellulose ester solution are combined. In order to precipitate the cellulose ester from the cellulose ester solution, the poor solvent solvent When mixing with the cellulose ester solution step by step while changing the seed and composition ratio, it means a solvent in which all the poor solvents used are combined.

In the present invention, the cellulose ester solution may be a solution containing a cellulose ester. The solvent used for obtaining the cellulose ester solution may be any solvent as long as it dissolves the cellulose ester, but preferably has an SP value of 18.5 to 29.0 (MPa) ^1/2. . Solvents having an SP value outside the above range are difficult to dissolve the cellulose ester.

The solubility parameter (SP value) of the solvent referred to in the present invention is a value represented by the square root of the molecular aggregation energy, and is described in Polymer Hand Book (Second Edition) Chapter IV Solubility Parameter Values. . The unit is (MPa) ^1/2 and indicates a value at 25 ° C. In addition, R.D. F. It can be calculated by the method described in Fedors, Polymer Engineering Science, 14, p147 (1967).

Hereinafter, as an organic solvent whose SP value according to the present invention is 18.5 to 25.0 (MPa) ^1/2 (hereinafter, description of units of SP value is omitted), for example, ethyl acetate (18. 6), tetrahydrofuran (18.6), benzene (18.8), trichloroethyl (18.8), methyl ethyl ketone (19.0), chloroform (19.0), methylene chloride (19.8), acetone (20 .2), acetic acid (20.7), pyridine (21.9), n-butanol (23.3), isopropyl alcohol (23.5), dimethylformamide (24.8) and the like. The numerical value in the parenthesis represents the SP value. The SP value is preferably 18.5 to 23.5, and more preferably the SP value is 18.5 to 22.0. Preferred solvents include ethyl acetate, tetrahydrofuran, methyl ethyl ketone, methylene chloride, acetone and acetic acid. Furthermore, these solvents may be combined with any solvent as long as the SP value is in the range of 18.5 to 29.0. Preferred combinations include, for example, a mixed solvent of acetic acid and water (a mass ratio of acetic acid / water of 100/0 to 65/35), a mixed solvent of acetic acid and methanol (a mass ratio of acetic acid / methanol of 100/0 to 6). / 94 range), mixed solvent of acetone and methanol (mass ratio of acetone / methanol is in the range of 100/0 to 8/92), mixed solvent of acetic acid, methanol and water, mixed solvent of acetone, methanol and water, etc. In addition, additives and the like may be contained.

  In the present invention, when preparing the cellulose ester solution using a mixed solvent, there is no limitation in the order of addition of the solvent, and the solvent adjusted so that the SP value falls within the range of 18.5 to 29.0 is used as the cellulose ester. You may add and you may add a cellulose ester to the solvent which adjusted SP value. Moreover, when preparing the said cellulose-ester solution using several types of solvent, it adjusts so that SP value may enter in the range of 18.5-29.0 in a system, adding a solvent to a cellulose ester sequentially. May be.

  Although there is no restriction | limiting in particular in the amount of solvent used by this invention, It is preferable that the solid content concentration of the cellulose ester in the said cellulose-ester solution before mixing with the said poor solvent is 5-30 mass%. If it exceeds 30% by mass, gelled foreign substances are easily taken into the solid when the cellulose ester is precipitated, and if it is 5% by mass or less, the amount of the poor solvent used is remarkably increased, so that productivity is lowered.

  In the present invention, the temperature of the step of dissolving the cellulose ester is not particularly limited as long as it is not higher than the boiling point of the solvent and the temperature at which the cellulose ester is dissolved, but is preferably -20 to 70 ° C, more preferably. 0-50 ° C.

<Poor solvent>
The “poor solvent” as used herein refers to a solvent in which the cellulose ester does not dissolve at 10% by mass or more at 20 ° C., and refers to a solvent added to precipitate the cellulose ester from the cellulose ester solution. Moreover, in the manufacturing process of a cellulose ester, the solvent added in order to precipitate a cellulose ester after the neutralization reaction performed after the aging process for performing partial hydrolysis is called a poor solvent, and the aging process is not performed. The solvent added to precipitate the cellulose ester after the neutralization reaction performed after the acylation reaction step is called a poor solvent.

  The poor solvent according to the present invention is characterized in that the SP value of the whole poor solvent is 30.0 or more and 40.0 or less, and the maximum SP value of the poor solvent to be mixed is 45.0 or less. To do.

  The whole poor solvent is a solvent in which all the poor solvents used for precipitating the cellulose ester from the cellulose ester solution are combined. Also, in order to precipitate cellulose ester from the cellulose ester solution, when mixing with the cellulose ester solution step by step while changing the solvent type and composition ratio of the poor solvent, it is a solvent that combines all the poor solvents used. The whole poor solvent.

  The maximum SP value of the poor solvent to be mixed is when the cellulose ester solution is stepwise mixed while changing the solvent type and composition ratio of the poor solvent in order to precipitate the cellulose ester from the cellulose ester solution. The SP value of the poor solvent is the largest value in each stage of mixing the cellulose ester solution and the poor solvent.

  When the SP value of the whole poor solvent is less than 30.0, the cellulose ester is not sufficiently precipitated, causing problems such as a significant decrease in yield and a significant deterioration in filterability. When the SP value of the whole poor solvent exceeds 40.0, gel foreign substances are easily taken into the precipitated solid when the cellulose ester solution and the poor solvent are mixed, and the effect of removing the gel foreign substances decreases. .

  In the present invention, as the poor solvent having an SP value of 30.0 or more and 40.0 or less, two or more solvents having different SP values may be used in combination, but a mixed solvent of water and an organic solvent is preferable. As a preferable mixed solvent of water and organic solvent, for example, a mixed solvent of water and alcohols (methanol, ethanol, isopropyl alcohol, butanol, etc.), a mixed solvent of water and acetic acid, a mixed solvent of acetone and water, water and acetic acid and Examples include a mixed solvent of alcohols (methanol, ethanol, isopropyl alcohol, butanol, etc.), a mixed solvent of water, acetone, and alcohols (methanol, ethanol, isopropyl alcohol, butanol, etc.). The alcohol is preferably methanol or ethanol, more preferably methanol.

  In the present invention, the entire poor solvent may be added with a solvent having an SP value adjusted to a range of 30.0 to 40.0, and the SP value of the entire poor solvent is a range of 30.0 to 40.0. It may be added stepwise while changing the composition ratio and solvent type. When adding stepwise while changing the composition ratio and solvent type of the poor solvent, the SP value of the poor solvent added stepwise needs to be 45.0 or less. When a poor solvent having an SP value exceeding 45.0 is added, a part of the gel-like foreign matter is deposited, so that even if the SP value of the whole poor solvent is adjusted within the range of 30.0 or more and 40.0 or less. The effect of reducing gel-like foreign matter is reduced.

  The amount of the poor solvent used in the present invention is preferably 0.5 times to 10.0 times, more preferably 1.0 times to 5.0 times, based on the mass of the cellulose ester solution. The composition of the cellulose ester solution and the entire poor solvent is adjusted so that the cellulose ester is precipitated within this range, and the maximum SP value of the poor solvent to be mixed is adjusted to 45.0 or less. Thus, a remarkable reduction effect can be obtained for the gel-like foreign matter.

<Alcohols>
In the present invention, the cellulose ester solution or that contain alcohols to at least one of the poor solvent. By precipitating the cellulose ester in a state containing the alcohols, aggregation of the cellulose ester is suppressed, and a precipitate can be obtained in a more uniform state. In addition, since the alcohols are contained, the dissolution or dispersion of the gel-like foreign matter is promoted, so that the content of the gel-like foreign matter in the cellulose ester obtained by precipitation can be greatly reduced.

  The alcohol according to the present invention is not particularly limited as long as it is an alcohol having a hydroxyl group (hydroxyl group), but is preferably an aliphatic alcohol. Examples of aliphatic alcohols include methanol, ethanol, propanol, isopropanol, n-butanol, ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, ethylene glycol monomethyl ether, propylene glycol monomethyl ether, and the like. Methanol, ethanol, ethylene glycol, and propylene glycol are preferable, methanol and ethanol are more preferable, and methanol is most preferable.

The amount of alcohol used in the present invention, relative to the weight of cellulose ester, is less than 10 times 0.5 times or more.

In the present invention, alcohols may be contained in one or both of the cellulose ester solution and the poor solvent. As a method of adding alcohols to the cellulose ester solution, a method of mixing the cellulose ester solution and alcohols, a method of preparing a cellulose ester solution by mixing a mixed solvent containing alcohols and a cellulose ester, cellulose Examples thereof include a method of preparing the cellulose ester solution by adding another solvent after mixing an ester and an alcohol. In addition, in the cellulose ester production process, the alcohol added in the reaction stopping process or the aging process is excessive, and the residual amount of alcohol is in the range of 0.5 to 10 times the mass of the cellulose ester. You may adjust so that it becomes. Moreover, when performing a filtration process, since a gel-like foreign material melt | dissolves or disperses by adding alcohol before a filtration process, the reduction effect of the gel-like foreign material by filtration cannot fully be acquired. From this, when performing a filtration process, the method of adding alcohol after a filtration process is preferable.

<Precipitation process>
In the present invention, the method of mixing the cellulose ester solvent and the poor solvent in the case of precipitating the cellulose ester by mixing the cellulose ester solution and the poor solvent may add the cellulose ester solution to the poor solvent, The poor solvent may be added to the cellulose ester solution, but a method of adding the poor solvent to the cellulose ester solution is preferable.

  The SP value of the solvent after mixing the cellulose ester solution and the poor solvent is preferably in the range of 28.0 to 40.0. By adjusting the SP value within the above range, precipitation of gel-like foreign matters and incorporation into cellulose esters can be suppressed, and the effect of reducing gel-like foreign matters can be sufficiently obtained. However, in order to precipitate the cellulose ester, the SP value after mixing the cellulose ester solution and the poor solvent needs to be larger than the SP value of the cellulose ester solution.

  Although there is no restriction | limiting in the temperature at the time of mixing the said cellulose-ester solution and the said poor solvent, below the boiling point of a solvent is preferable, More preferably, it is -10 degreeC-60 degreeC, More preferably, it is 0-50 degreeC. However, it has been found that when an acidic solvent such as acetic acid is contained in the cellulose ester solution, the hydrolysis of the cellulose ester proceeds and the gelled foreign matter increases remarkably by heating. For this reason, when an acidic solvent such as acetic acid is contained in the cellulose ester solution, the temperature when mixing with the poor solvent is preferably −10 ° C. to 40 ° C., more preferably −10 ° C. to 30 ° C. . The temperature lowering may be performed by water cooling or the like, or may be performed continuously or stepwise. In such temperature decrease, the temperature decrease rate may be, for example, about 1 to 20 ° C., preferably 3 to 18 ° C., and more preferably about 5 to 15 ° C. per hour.

  The cellulose ester solution and the poor solvent are preferably mixed with stirring. In the case of performing the stirring, the stirring speed depends on the scale (manufacturing scale), but may be, for example, 10 to 10000 rpm, preferably 20 to 5000 rpm, more preferably 30 to 3000 rpm, particularly about 50 to 2000 rpm. Good. In particular, the stirring speed is 10 to 2000 rpm (for example, 20 to 1500 rpm), preferably 30 to 1000 rpm (for example, 40 to 800 rpm), more preferably 50 to 500 rpm (for example, 60 to 300 rpm), particularly about 70 to 200 rpm. There may be. The stirring speed is desirably large enough for granulation. When the stirring speed is too low, localization of the poor solvent to be added and uneven temperature distribution may occur, and the effect of reducing gelled foreign substances may be reduced.

  In the present invention, “the poor solvent having a total SP value of the cellulose ester solution and the poor solvent in the range of 30.0 to 40.0 and the maximum SP value of the poor solvent to be mixed is 45.0 or less. The “mixing and precipitating the cellulose ester” may be performed in the cellulose ester production process.

  Below, the manufacturing process of a cellulose ester is demonstrated.

[Activation process]
In the activation step, cellulose is treated with an activator to activate the cellulose. In the present invention, raw material cellulose is supplied in a slurry wet state.

  As the activator for activating cellulose, a solvent for acylation reaction (acylation solvent) is usually used. As the acylation solvent, organic carboxylic acids such as formic acid, acetic acid, propionic acid, butyric acid, isobutyric acid are used. Or an aliphatic carboxylic acid (linear or branched C1-6 alkanoic acid) such as valeric acid. These activators can be used alone or in combination of two or more.

  In the activation treatment, an aqueous medium containing water is used as the activator. This aqueous medium may be an aqueous medium containing an organic carboxylic acid. In consideration of substituting the aqueous medium from the cellulose raw material with the carboxylic acid used in the reaction prior to the reaction following the activation treatment, it is economical. It is preferable to use many organic carboxylic acids.

  The activation step is not limited to a single activation step, and may be constituted by a plurality of activation steps, and can be performed using activators having different acylation catalyst concentrations. For example, the acylating catalyst may be composed of a first activating step for activating cellulose with an activating agent and a second activating step for activating cellulose with an activating agent containing an acylating catalyst. You may comprise in the 1st process of processing cellulose with the activator with a low density | concentration, and the 2nd process of processing cellulose with the activator with the high density | concentration of an acylation catalyst.

  The amount of the activator used is, for example, about 25 to 150 parts by mass, preferably 30 to 125 parts by mass, and more preferably about 50 to 100 parts by mass (for example, 70 to 100 parts by mass) with respect to 100 parts by mass of cellulose. It may be.

  The activation treatment may be performed by treating cellulose with an activator, spraying the activator on cellulose, or immersing cellulose in the activator. Usually, raw material cellulose is often added to the activator to form a slurry. The activation treatment temperature can be selected from the range of 0 ° C to 100 ° C. In order to perform the activation treatment without applying an industrial load, it is usually 10 ° C to 40 ° C, preferably about 15 ° C to 35 ° C. It is. The activation treatment time can be selected in the range of 0.1 to 72 hours, and is usually about 0.1 to 3 hours, preferably about 0.2 to 2 hours.

  When the solvent used for pulverizing the raw material cellulose is a carboxylic acid, the activation process proceeds at the fine pulverization stage, so that the standing time is short, and it can be immediately put into the esterification reaction vessel.

  When a solution other than carboxylic acid such as water is used for pulverizing the raw material cellulose, the activation treatment is completed by washing with carboxylic acid several times, replacing with carboxylic acid, and allowing to stand.

[Esterification process]
The cellulose activated by the activation treatment is esterified with a carboxylic acid (containing at least one or more) having an acyl group having at least 2 carbon atoms and a carboxylic anhydride (containing at least one or more) in the presence of an acid catalyst. . As the acid catalyst, Lewis acid or strong acid can be used, but sulfuric acid is generally used.

  Usually, an acid anhydride [for example, an acid anhydride of a carboxylic acid having 2 or more carbon atoms (carboxylic anhydride)], for example, C2-6 alkanoic anhydride such as acetic anhydride, propionic anhydride, butyric anhydride, valeric anhydride, etc. Things can be used. A carboxylic acid having an acyl group having at least 2 carbon atoms (for example, at least a C2-6 carboxylic anhydride) is used. You may use these individually or in combination of 2 or more types. As long as it has an acyl group and is easily acylated, it is not limited to carboxylic acids, and organic acid halides can also be used.

  The amount of the acid catalyst (especially sulfuric acid) used in the esterification step is, for example, from 3 to 20 parts by mass, preferably from 5 to 18 parts by mass, more preferably from about 7 to 15 parts by mass with respect to 100 parts by mass of cellulose. It can be selected and is usually about 7 to 15 parts by mass.

  As the esterification solvent, an esterification solvent corresponding to at least an acyl group having 2 or more carbon atoms, for example, a carboxylic acid (acid anhydride) may be used, and for example, selected from acid anhydrides corresponding to C2-6 carboxylic acid A plurality of acid anhydrides having different carbon numbers may be used. For example, propionic anhydride and / or butyric anhydride and acetic anhydride may be used in combination.

  Preferred esterification solvents are a combination of acetic anhydride and propionic anhydride, a combination of acetic anhydride and butyric anhydride, and a combination of acetic anhydride, propionic anhydride and butyric anhydride. In particular, a combination of acetic anhydride and propionic anhydride, and a combination of acetic anhydride and butyric anhydride are preferable. Acetic anhydride is more reactive than propionic anhydride and the like, and in the case of obtaining a cellulose mixed fatty acid ester having a low degree of acetyl group substitution, acetic anhydride is not used or the object of the present invention is not impaired. The esterification solvent having at least 3 carbon atoms and corresponding to the acyl group may be combined with a small amount of acetic anhydride.

  In the case of obtaining a cellulose ester having an acyl group having 3 or more carbon atoms, the esterification solvent may correspond to an acyl group having 3 or more carbon atoms, for example, propionic anhydride, if acylation or aging can be performed in the presence of acetic acid. What is necessary is just to comprise by butyric anhydride etc., and it does not necessarily need to contain the esterification solvent (acetic anhydride) corresponding to an acetyl group. In order to introduce an acetyl group, acetic anhydride is not necessarily used, and the reaction may be carried out in the presence of acetic acid.

  Such acetic acid may be present in the reaction system in the esterification step and the ripening step (particularly at least the ripening step), and may be composed only of acetic acid derived from the activation treatment. May be newly added, and may be used as an esterification solvent in an ordinary esterification step.

  In addition, when producing a cellulose ester using a plurality of esterification solvents, in the esterification step, a plurality of esterification solvents may coexist in the reaction system, and after esterifying cellulose with a specific esterification solvent The cellulose may be esterified with another esterification solvent. The usage-amount of the esterification solvent in an esterification process is 1.1-4 equivalent with respect to the hydroxyl group (hydroxyl group) of a cellulose, for example, Preferably it is 1.1-2 equivalent, More preferably, it is 1.3-1. About 8 equivalents.

  In the esterification step, an esterification solvent (organic carboxylic acid such as acetic acid, propionic acid, butyric acid) is usually used as a solvent or diluent. The amount of the esterification solvent (carboxylic acid) used is about 50 to 700 parts by weight, preferably 150 to 600 parts by weight, and more preferably about 200 to 550 parts by weight with respect to 100 parts by weight of cellulose.

  In addition, esterification reaction can be performed at the temperature of about 0-50 degreeC, Preferably it is 5-45 degreeC, More preferably, it is about 10-40 degreeC. The esterification reaction may be performed at a relatively low temperature of 10 ° C. or less (0 to 10 ° C.) in the initial stage. The reaction time at such a low temperature may be, for example, 30 minutes or more, 40 minutes to 2 hours, preferably about 45 to 100 minutes) from the start of the esterification reaction. The esterification time at 10 to 50 ° C. is 10 minutes or longer and 20 to 90 minutes, preferably 30 to 80 minutes, 40 minutes to 75 minutes.

  When a uniform reaction system is formed, it can be determined that the esterification reaction has been completed.

  After completion of the esterification reaction, the hydrolysis reaction may be started, or the esterification solvent, the esterification solvent, and the acid catalyst may be left in the aging step as they are.

[Esterification reaction stopping step]
When the hydrolysis reaction is performed in order to deactivate the esterification solvent after the esterification reaction, it is sufficient if the esterification solvent can be deactivated, and usually at least water is often included. The quenching agent that promotes hydrolysis may be composed of water and at least one selected from esterification solvents, alcohols, and neutralizing agents. More specifically, as the quencher, for example, water alone, a mixture of water and carboxylic acid, a mixture of water and alcohols, a mixture of water and neutralizer, water, organic carboxylic acid and alcohols And a mixture of a neutralizing agent and the like.

  Examples of the neutralizing agent include bases that can neutralize part of the acid catalyst or esterification solvent, such as alkali metal compounds (hydroxides such as sodium hydroxide and potassium hydroxide, carbonates such as sodium carbonate and potassium carbonate, etc. , Organic acid salts such as sodium acetate and potassium acetate), alkaline earth metal compounds (eg, hydroxides such as calcium hydroxide, carbonates such as calcium carbonate, organic acid salts such as calcium acetate and magnesium acetate) And may be used alone or in combination of two or more. Examples of alcohols include linear alcohols (ethanol, methanol, propanol, etc.). These alcohols can also be used alone or in combination of two or more.

  The ratio of water and esterification solvent or water and alcohol can be selected from a range of about 20 to 140 parts by mass of esterification solvent or alcohol with respect to 100 parts by mass of water, and usually 25 to 120 parts by mass, preferably Is 50 to 100 parts by mass.

  The hydrolysis after the esterification step and before the ripening step may contain a neutralizing agent in a ratio of partially neutralizing the acid catalyst or may not contain a neutralizing agent. The preferred deactivator may be water alone, but since water is a poor solvent for cellulose esters, there is a high possibility that cellulose esters other than the desired degree of substitution will precipitate. And a mixed solution is preferable.

  Since the reaction component contained in the raw material cellulose is not 100%, an unreacted component is included at this stage. Therefore, a process of filtering the reaction solution once may be introduced.

  This reaction stopping step can be omitted if necessary.

[Filtering process]
It is preferable to provide a filtration step between the esterification step and an aging step described later.

  The solution after completion of the esterification reaction contains unacetylated, low-acetylated components and impurities that did not react with the raw material cellulose. Time is further shortened, and specific cleavage of molecular chains and substituents occurring in the reaction solution is difficult to occur. The film surface quality of the film formed using the obtained cellulose ester is cellulose without filtration. Even better than the ester.

  Filter media used for filtration preferably have low absolute filtration accuracy, but if the absolute filtration accuracy is too low, the filter media is likely to be clogged, and the filter media must be replaced frequently, reducing productivity. There is a problem of making it.

  The material of the filter medium is not particularly limited, and a normal filter medium can be used. However, a filter medium made of plastic such as polypropylene, polyester, and PTFE, a filter medium made of glass fiber, and a metal filter medium such as stainless steel fiber can be used. This is preferable because there is no dropout.

  Since the cellulose ester slurry contains an acid, a metal filter is easily corroded, and therefore, a filter made of glass fiber or plastic fiber is more preferable.

  When performing filtration using a metal filter between the esterification process and the aging process, it is possible to neutralize and deactivate sulfuric acid and carboxylic anhydride and then move to the filtration process without worrying about corrosion. Can be used.

  In the present invention, it is preferable to use a pressure filter equipped with the filter medium.

[Aging process]
In the ripening step, after the esterification reaction is almost completed, the acylation is performed to obtain a desired degree of substitution, and after the completion of the deacylation, a neutralizing agent is added to complete the series of reactions. .

  When the acid catalyst used for esterification is neutralized, the required amount of acid catalyst may be added again, or used in the aging process without neutralizing the acid catalyst (especially sulfuric acid) used in the esterification process. May be. An acid catalyst other than the acid catalyst used in the esterification may be added.

  If sulfuric acid is too much, the molecular weight may be reduced. Therefore, it is preferable to use the acid catalyst used in the esterification step as it is without adding an acid catalyst in the aging step.

  In addition, in the stage where the acid catalyst is neutralized later, the alkali metal or alkaline earth metal contained in the neutralizing agent is added in the neutralizing agent, and remains in the purified cellulose ester. It is preferable not to add sulfuric acid in the aging process because it can be an obstacle.

  In addition, a deacylation solvent (such as a mixed solution of water and carboxylic acid) may be newly added as necessary when aging.

  The reaction temperature during the aging step is preferably 20 ° C. to 90 ° C., preferably 25 ° C. to 80 ° C., more preferably 30 ° C. to 70 ° C. The aging reaction may be performed in a nitrogen atmosphere, and in an air atmosphere You may go on.

  The aging reaction time can be selected from the range of 20 minutes or more and 25 minutes to 6 hours, preferably 30 minutes to 5 hours, and more preferably 1 to 3 hours.

[Neutralization process]
After the desired cellulose ester is obtained in the aging step, it is necessary to neutralize the acid catalyst used for deacylation. As the neutralizing agent, it is preferable to add a neutralizing agent composed of a base described in the esterification reaction stopping step.

  The reaction product (dope containing cellulose mixed fatty acid ester) is put into a precipitation solvent (water, aqueous acetic acid solution, etc.) to separate the cellulose mixed fatty acid ester, and free metal components and sulfuric acid components are removed by washing with water. May be. In addition, a neutralizing agent can also be used in the case of washing with water.

[Post-treatment process (precipitation, filtration, washing, drying)]
After neutralizing the acid catalyst in the neutralization step, the product is precipitated by precipitation.

  As a poor solvent for precipitation, a mixed solution of water and carboxylic acid is preferably used, but is not limited to these poor solvents, and ketones, alcohols, ethers, esters and the like alone or in a water mixed solvent There may be.

  The process of filtering and washing the precipitated product is repeated until the free acid concentration is 500 ppm or less, preferably 300 ppm or less, and more preferably 150 ppm or less.

  Thereafter, the desired cellulose ester is obtained by drying with dry air.

  In the present invention, a poor solution in which the cellulose ester solution and the entire poor solvent SP value are in the range of 30.0 to 40.0 and the maximum SP value of the poor solvent to be mixed is 45.0 or less is mixed. Thus, the production method for precipitating the cellulose ester is most effective when used in the product precipitation step in the post-treatment step for the purpose of reducing gelled foreign matter. Moreover, you may reduce a gel-like foreign material by the manufacturing method of this invention once using the taken-out cellulose ester.

<Filtration>
According to the present invention, a cellulose ester solution and a poor solvent having a total SP value in the range of 30.0 to 40.0 and a poor solvent having a maximum SP value of 45.0 or less are mixed. Then, the step of precipitating the cellulose ester is more preferably combined with the filtration step.

  The filtration step to be combined is preferably a method in which a solution obtained by adding carboxylic acid to cellulose acylate is filtered either before the start of the acylation step or before the reprecipitation step.

  Various known filtration devices can be used for filtering the cellulose ester solution. That is, when roughly classified as a filter, it can be divided into a continuous filter and a batch pressure filter, and as a continuous filter, it can be divided into a belt type, a multiple disk type, a screw press type, a filter press type, etc. Examples of the batch pressure filter include a leaf type and a candle type.

  A filter press device, a paper filter device, a leaf filter device, a drum filter device, a precoat filter device, or the like can be used. The industrially most advantageous product is a filter press apparatus, and the filter press apparatus may be pre-coated and used. As an example of the filter press apparatus, 40 to 50 plates of about 60 cm square are used, and a net is attached to each plate, and a filter paper or cotton cloth is installed between the nets. A plurality of these filter press apparatuses may be used for filtration in multiple stages.

  Moreover, it is a leaf filter apparatus and can be used suitably.

  As the filter medium, a sintered metal filter, a non-woven metal filter, a cotton cloth filter, a paper filter, or the like may be used.

  If it is a filter press type, the filter medium to be used can be a natural fiber or a synthetic fiber. In general, polypropylene, polyester (tetron), and nylon can be used as the material of the synthetic fiber used for the filter cloth. Vinylon, acrylic, saran, etc. can also be used depending on the solvent. Each of these materials has characteristics on the material and can be used according to the characteristics. If it is a natural fiber, cotton can be mentioned as a typical material. Monofilaments, multifilaments, spun yarns and the like can be used as the type of raw yarn used for the filter cloth. When a monofilament is used, the cake peelability is excellent and clogging is small, but there is a disadvantage that the fine particles are poorly captured. When multifilaments are used, the strongest filter cloth is obtained and the cake peelability is good. In the case of spun yarn, cake peeling is poor and clogging is slightly faster. The filter cloth weave includes plain weave, twill weave, and satin weave. In the case of plain weave, particles are easily collected but clogging is accelerated. In the case of twill weave, a filter cloth having a good balance between collection and clogging can be obtained. In the case of satin weaving, particles are less clogged, but the ability to collect particles is poor. In the present invention, plain or twill filter cloth is suitable.

For cotton cloth filters, cotton flannel (No. 10 B, plain weave diameter No. 20 single yarn 63, weft No. 10 single yarn 46), gold width (No. 11, plain weave diameter No. 40 single yarn 100, weft No. 40 single yarn 98 pieces ), Thick twill (26, twill, 12-3, 64, 12-4, 32) may be used. In the paper filter, filter paper (300 g / m ² ) or the like may be used. These filter media may be used in combination (for example, the first filter media is one cotton flannel filter paper, the second filter media is two cotton flannels, one gold width, and the third filter media is one cotton flannel one filter paper, one gold width).

  The retention particle size of the filter medium is preferably 1 to 50 μm. 2-20 micrometers is further more preferable, and 3-15 micrometers is the most preferable. By using such a filter medium, filterability is improved and productivity is improved.

  The pressure in the filtration step can be appropriately set in consideration of the filtration efficiency. Specifically, the filter medium may be pressurized to 5 to 18 atmospheres (for example, 8 to 18 atmospheres, for example, 10 to 18 atmospheres). The shape of the cellulose mixed fatty acid ester composition obtained by dissolving cellulose ester in an organic solvent, filtering and drying may be a filament. In the step of dissolving the cellulose mixed fatty acid ester according to the present invention in an organic solvent and filtering, kaolin, titanium oxide, clay or the like may be used as a filter aid. The filtrate may be kept warm at about 40-50 ° C. The filter medium may be pressurized to 5 to 18 atmospheres (for example, 8 to 18 atmospheres, for example, 10 to 18 atmospheres). Filtration multiple times instead of one time (for example, the first filter medium is one cotton flannel paper, the second filter medium is two cotton flanks, one gold width, the third filter medium is one cotton flannel one filter paper and one gold width one) In the same configuration, the first filtration may be performed at 12 to 18 atmospheres, the second filtration may be performed at 8 to 14 atmospheres, and the third filtration may be performed at 5 to 9 atmospheres). When the same filter medium configuration is used, the filtration pressure may be changed between the first time and the second time (for example, the second filtration is performed at a lower pressure).

  The retained particle size of the filter used for filtration is preferably -30 μm, more preferably 1-20 μm, and even more preferably 2-20 μm. By setting the retained particle size of the filter to 0.1 μm or more, it tends to be able to suppress a significant increase in the filtration pressure and facilitate industrial production. Moreover, since fine foreign substances can be removed by setting the retained particle size to 40 μm or less, it is effective when combined with the precipitation step according to the present invention. Further, filtration may be performed by combining filters having different retention particle sizes.

  The temperature at the time of filtration can be any temperature as long as filtration is possible, but it is preferably 30-100 ° C, more preferably 35-80 ° C, and even more preferably 40-70 ° C. This is preferable because the viscosity of the solution can be lowered.

  The filtration pressure is preferably in the range of 0.001 MPa to 10 MPa, more preferably in the range of 0.001 MPa to 5 MPa, and more preferably in the range of 0.01 MPa to 1 MPa.

  In addition, as a filter aid, celite (for example, Celite [Filter-Cel, Celite 505, Standard Super-Cel, Celite 512, Hyflo Super-Cel, manufactured by Johns-Manville Sales Corp.), Celite 501, Celite 503, Celite 535, Celite 545, Celite 560, etc.], Dicalite (Superref, Specified Spipe, Special Spec, manufactured by Grefco, Inco, USA) , Speedex etc.), radio lights (RADIOLITE # 100, RA manufactured by Showa Chemical Industry Co., Ltd.) IOLITE # 200, RADIOLITE # 500, RADIOLITE # 600, RADIOLITE # 700, RADIOLITE # 900, RADIOLITE # 1100, RADIOLITE # 100), layered clay mineral (preferably talc, mica, kaolinite), silicon dioxide fine particles (for example, Silicon dioxide fine particles (for example, silica gel MB-300, MB-500 manufactured by Fuji Silysia Co., Ltd., Fuji Silica Gel AB Type, Fuji Silica Gel A Type, Fuji Silica Gel RD Type, BW-25K, Merca Silica Gel 40, Silica Gel 60, Silica Gel 100, etc.) These filter aids may be mixed with a cellulose ester solution and subjected to cake filtration, or precoated on a filter medium. Then, the solution in which the cellulose ester is dissolved may be filtered.

<Additives>
(Sugar ester compound)
Examples of the polyester resin added to the cellulose ester include sugar ester compounds.

  Examples of the sugar ester compound include an ester compound in which at least one pyranose structure or at least one furanose structure is 1 to 12 and all or part of the OH groups in the structure are esterified.

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

  Examples of the sugar as a raw material for synthesizing the sugar ester compound include the following, but the present invention is not limited thereto.

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

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

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

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

  The monocarboxylic acid used for esterifying all or part of the OH groups in the pyranose structure or furanose structure is not particularly limited, and known aliphatic monocarboxylic acid, alicyclic monocarboxylic acid, aromatic A group monocarboxylic acid or the like can be used. The carboxylic acid used may be one kind or a mixture of two or more kinds.

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

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

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

  As a compound having 1 to 12 at least one of pyranose structural units or furanose structural units, an oligosaccharide ester compound can be applied.

  An oligosaccharide is produced by allowing an enzyme such as amylase to act on starch, sucrose, etc., and examples of the oligosaccharide include maltooligosaccharide, isomaltooligosaccharide, fructooligosaccharide, galactooligosaccharide, and xylo-oligosaccharide. .

  Examples of sugar ester compounds are listed below, but the present invention is not limited thereto.

  Monopet SB: manufactured by Daiichi Kogyo Seiyaku Co., Ltd., Monopet SOA: manufactured by Daiichi Kogyo Seiyaku Co., Ltd.

  As addition amount of these sugar ester compounds, it is preferable to contain 0.5-30 mass% with respect to the total mass of the said polymer (A) and a cellulose ester, and it is contained especially 5-20 mass%. preferable.

(Plasticizer)
The optical film according to the present invention can contain a plasticizer. The plasticizer is not particularly limited, but is preferably a polycarboxylic acid ester plasticizer, a glycolate plasticizer, a phthalate ester plasticizer, a fatty acid ester plasticizer, a polyhydric alcohol ester plasticizer, or a polyester. It is selected from plasticizers, acrylic plasticizers and the like. Of these, when two or more plasticizers are used, at least one plasticizer is preferably a polyhydric alcohol ester plasticizer.

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

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

General formula (a): Ra- (OH) _n
(However, Ra represents an n-valent organic group, n represents a positive integer of 2 or more, and an OH group represents an alcoholic and / or phenolic hydroxyl group (hydroxyl group).)
Examples of preferred polyhydric alcohols include the following, but the present invention is not limited to these. Adonitol, arabitol, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propanediol, dipropylene glycol, tripropylene glycol, 1,2-butanediol, 1,3- Butanediol, 1,4-butanediol, dibutylene glycol, 1,2,4-butanetriol, 1,5-pentanediol, 1,6-hexanediol, hexanetriol, galactitol, mannitol, 3-methylpentane- Examples include 1,3,5-triol, pinacol, sorbitol, trimethylolpropane, trimethylolethane, xylitol and the like. In particular, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, sorbitol, trimethylolpropane, and xylitol are preferable.

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

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

  As the aliphatic monocarboxylic acid, a fatty acid having a straight chain or 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 1-10. When acetic acid is contained, the compatibility with the cellulose ester is increased, and it is also preferable to use a mixture of acetic acid and another monocarboxylic acid.

  Preferred aliphatic monocarboxylic acids include acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, 2-ethyl-hexanoic acid, undecylic acid, lauric acid, tridecylic acid, Saturated fatty acids such as myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, heptacosanoic acid, montanic acid, melicic acid, 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 alkyl group, methoxy group or ethoxy group are introduced into the benzene ring of benzoic acid such as benzoic acid and toluic acid, biphenylcarboxylic acid, Examples thereof include aromatic monocarboxylic acids having two or more benzene rings such as naphthalenecarboxylic acid and tetralincarboxylic acid, or derivatives thereof. Benzoic acid is particularly preferable.

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

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

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

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

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

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

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

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

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

General formula (b): Rb (COOH) _m (OH) _n
(Where Rb is an (m + n) -valent organic group, m is a positive integer of 2 or more and 6 or less, n is an integer of 0 or more and 4 or less, a COOH group is a carboxyl group, and an OH group is an alcoholic or phenolic hydroxyl group. Represents a group (hydroxyl group).
Examples of preferred polyvalent carboxylic acids include the following, but the present invention is not limited to these. Trivalent or higher aromatic polyvalent carboxylic acids such as trimellitic acid, trimesic acid, pyromellitic acid or derivatives thereof, succinic acid, adipic acid, azelaic acid, sebacic acid, oxalic acid, fumaric acid, maleic acid, tetrahydrophthal An aliphatic polyvalent carboxylic acid such as an acid, an oxypolyvalent carboxylic acid such as tartaric acid, tartronic acid, malic acid and citric acid can be preferably used. In particular, it is preferable to use an oxypolycarboxylic acid from the viewpoint of improving retention.

  There is no restriction | limiting in particular as alcohol used for the said polyhydric carboxylic acid ester compound, Well-known alcohol and phenols can be used. For example, an aliphatic saturated alcohol or aliphatic unsaturated alcohol having a straight chain or side chain having 1 to 32 carbon atoms can be preferably used. It is more preferable that it is C1-C20, and it is especially preferable that it is C1-C10. In addition, alicyclic alcohols such as cyclopentanol and cyclohexanol or derivatives thereof, aromatic alcohols such as benzyl alcohol and cinnamyl alcohol, or derivatives thereof can also be preferably used.

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

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

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

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

  Examples of preferred aromatic monocarboxylic acids include those in which an alkyl group is introduced into the benzene ring of benzoic acid such as benzoic acid and toluic acid, and two or more rings such as biphenylcarboxylic acid, naphthalenecarboxylic acid, and tetralincarboxylic acid. Aromatic monocarboxylic acids possessed by them, or derivatives thereof.

  Of these monocarboxylic acids, acetic acid, propionic acid, and benzoic acid are particularly preferable.

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

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

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

(Acid value)
The acid value in the present invention refers to the number of milligrams of potassium hydroxide necessary for neutralizing the acid (carboxyl group present in the sample) contained in 1 g of the sample. The acid value is measured according to JIS K0070.

  Examples of particularly preferred polyvalent carboxylic acid ester compounds are shown below, but the present invention is not limited thereto. For example, triethyl citrate, tributyl citrate, acetyl triethyl citrate (ATEC), acetyl tributyl citrate (ATBC), benzoyl tributyl citrate, acetyl triphenyl citrate, acetyl tribenzyl citrate, dibutyl tartrate, diacetyl dibutyl tartrate, Examples include tributyl trimellitic acid and tetrabutyl pyromellitic acid.

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

General formula (c): B-COO-((G-O-) _m- CO-A-COO-) _n G-O-CO-B
(In the formula, B represents a benzene ring and may have another substituent. G represents an alkylene group having 2 to 12 carbon atoms, an arylene group having 6 to 12 carbon atoms, or an oxyalkylene having 4 to 12 carbon atoms. Group A represents an alkylene group having 2 to 10 carbon atoms or an arylene group having 4 to 10 carbon atoms, and m and n represent a repeating unit.)
The compound of the general formula (c) includes a benzene monocarboxylic acid group represented by BCOOH, an alkylene glycol group, an oxyalkylene glycol group or an aryl glycol group represented by HO— (GO—) ₁ H, HOCO-A It is synthesized from an alkylenedicarboxylic acid group or aryldicarboxylic acid group represented by —COO—H, and can be obtained by the same reaction as that of a normal polyester plasticizer.

  Examples of the benzene monocarboxylic acid component of the raw material of the polyester plasticizer include, for example, benzoic acid, para-tert-butylbenzoic acid, orthotoluic acid, metatoluic acid, p-toluic acid, dimethylbenzoic acid, ethylbenzoic acid, normal propylbenzoic acid, There are aminobenzoic acid, acetoxybenzoic acid and the like, and these can be used as one kind or a mixture of two or more kinds, respectively.

  Examples of the alkylene glycol component of the polyester plasticizer include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1,3-butanediol, 1,2-propane. Diol, 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-pentane Diol 1,6-hexanediol, 2,2,4-trimethyl 1,3-pentanediol, 2-ethyl 1,3-he There are sundiol, 2-methyl 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-octadecanediol, etc., and these glycols are used as one kind or a mixture of two or more kinds. used. In particular, an alkylene glycol having 2 to 12 carbon atoms is particularly preferable because of excellent compatibility with a cellulose ester.

  Examples of the oxyalkylene glycol component having 4 to 12 carbon atoms as the raw material for the aromatic terminal ester include diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, and tripropylene glycol. , One or a mixture of two or more.

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

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

(Acrylic polymer)
The optical film according to the present invention can also contain a (meth) acrylic polymer as a plasticizer.

  The (meth) acrylic polymer is preferably a polymer Y having a weight average molecular weight of 500 or more and 3000 or less obtained by polymerizing an ethylenically unsaturated monomer Ya having no aromatic ring.

  The (meth) acrylic polymer includes at least an ethylenically unsaturated monomer Xa having no aromatic ring and a hydroxyl group (hydroxyl group) in the molecule, and ethylene having a hydroxyl group (hydroxyl group) without an aromatic ring in the molecule. The weight average molecular weight 500 obtained by polymerizing the polymer X having a weight average molecular weight of 3000 to 30,000 obtained by copolymerization with the unsaturated unsaturated monomer Xb and the ethylenically unsaturated monomer Ya having no aromatic ring More preferably, it is a mixture of the polymer Y of 3000 or less.

  More preferably, the polymer X is represented by the following general formula (X), and the polymer Y is represented by the following general formula (Y).

Formula _{(X): - [CH 2} -C (Rc) (CO 2 Rd) -] m - [CH 2 -C (Re) (CO 2 Rf-OH) -] n - [Xc] p -
Formula _{(Y): Ry- [CH 2} -C (Rg) (CO 2 Rh-OH) -] k - [Yb] q -
(In the formula, Rc, Re and Rg represent H or CH _3. Rd represents an alkyl group having 1 to 12 carbon atoms and a cycloalkyl group. Rf and Rh represent —CH ₂ — and —C ₂ H ₄ —. Or represents C ₃ H ₆ —, Ry represents OH, H or an alkyl group having 3 or less carbon atoms, Xc represents a monomer unit polymerizable with Xa and Xb, and Yb represents a monomer copolymerizable with Ya. M, n, k, p and q represent molar composition ratios, where m ≠ 0, n ≠ 0, and k ≠ 0.
As addition amount of these plasticizers, it is preferable to contain 0.5-30 mass% with respect to the total mass of the said polymer (A) and a cellulose ester, It is preferable to contain especially 5-20 mass%. .

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

  The ultraviolet absorber is not particularly limited, and examples thereof include oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, triazine compounds, nickel complex compounds, inorganic powders, and the like. It is done.

  For example, 5-chloro-2- (3,5-di-sec-butyl-2-hydroxyphenyl) -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, There are tinuvins such as tinuvin 928, and these are all commercially available products from BASF Japan 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.

  The cellulose ester solution in the present invention preferably contains two or more ultraviolet absorbers. As the UV absorber, a polymer UV absorber can also be preferably used, and in particular, a polymer type UV absorber described in JP-A-6-148430 is preferably used.

  The method 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.

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

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

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

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

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

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

  The addition amount of these compounds is preferably 1 ppm to 1.0%, more preferably 10 to 1000 ppm in terms of mass ratio with respect to the total mass of the polymer (A) and the cellulose ester.

(Fine particles)
In the optical film according to the present invention, fine particles can be added after the cellulose acylate solution treatment step.

  Examples of the fine particles include inorganic compounds such as silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, and aluminum silicate. And magnesium silicate and calcium phosphate. Further, fine particles of an organic compound can also be preferably used. Examples of organic compounds include polytetrafluoroethylene, cellulose acetate, polystyrene, polymethyl methacrylate, polypropyl methacrylate, polymethyl acrylate, polyethylene carbonate, acrylic styrene resin, silicone resin, polycarbonate resin, benzoguanamine resin, melamine resin Also, pulverized and classified products of organic polymer compounds such as polyolefin-based powders, polyester-based resins, polyamide-based resins, polyimide-based resins, polyfluorinated ethylene-based resins, and starches. Alternatively, a polymer compound synthesized by a suspension polymerization method, a polymer compound made spherical by a spray drying method or a dispersion method, or an inorganic compound can be used.

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

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

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

  The content of these fine particles in the cellulose ester is preferably 0.01 to 1% by mass, particularly preferably 0.05 to 0.5% by mass.

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

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

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

  Among these, Aerosil 200V and Aerosil R972V are particularly preferably used because they have a large effect of reducing the friction coefficient while keeping the turbidity of the optical film low. In the said optical film, it is preferable that the dynamic friction coefficient of at least one surface is 0.2-1.0.

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

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

  In order to perform in-line addition and mixing in the present invention, for example, an in-line mixer such as a static mixer (manufactured by Toray Engineering), SWJ (Toray static type in-tube mixer Hi-Mixer) or the like is preferably used.

<Method for producing optical film>
The cellulose ester in the present invention can be formed as an optical film.

  A method for producing the optical film will be described.

  The optical film can be preferably used regardless of whether it is a film produced by a solution casting method or a film produced by a melt casting method.

[Melt casting method]
<Melted pellet manufacturing process>
The mixture of polymer, particulate matter, plasticizer and other additives that form a film used for melt extrusion is usually preferably kneaded and pelletized in advance.

  Pelletization may be performed by a known method. For example, a polymer, a plasticizer, and other additives that form a film are supplied to an extruder with a feeder, and are kneaded using a single-screw or twin-screw extruder. Extruded into a shape, water-cooled or air-cooled and cut.

  It is important for the raw materials to be pre-dried before extrusion in order to prevent decomposition of the raw materials. In particular, since the polymer forming the optical film is likely to absorb moisture, it is preferable that the polymer is dried at 70 to 140 ° C. for 3 hours or more with a dehumidifying hot air drier or a vacuum drier so that the moisture content is 300 ppm or less, and further 100 ppm or less.

  The additives may be mixed before being supplied to the extruder, or may be supplied by individual feeders. A small amount of an additive such as an antioxidant is preferably mixed in advance in order to mix uniformly.

  Mixing of the antioxidants may be performed by mixing solids, and if necessary, the antioxidant may be dissolved in a solvent and impregnated with a polymer forming an optical film, or may be mixed or sprayed. May be mixed.

A vacuum nauter mixer or the like is preferable because drying and mixing can be performed simultaneously. Further, if the contact with air, such as the exit from the feeder unit or die, it is preferable that the atmosphere such as dehumidified air and dehumidified N ₂ gas.

  The extruder is preferably processed at as low a temperature as possible so that the shearing force is suppressed and the resin can be pelletized so as not to deteriorate (molecular weight reduction, coloring, gel formation, etc.). For example, in the case of a twin screw extruder, it is preferable to rotate in the same direction using a deep groove type screw. From the uniformity of kneading, the meshing type is preferable.

  A film is formed using the pellets obtained as described above. It is also possible to feed the raw material powder directly to the extruder with a feeder and form a film as it is without pelletization.

<Process for extruding molten mixture from die to cooling roll>
The produced pellets are extruded using a single-screw or twin-screw type extruder, the melting temperature Tm at the time of extrusion is about 200 to 350 ° C., filtered by the filtration device according to the present invention to remove foreign matters, and then the film is formed from the T die. Cast on the cooling roll, solidify on the cooling roll, and cast while pressing with the elastic touch roll.

  When introducing into the extruder from the supply hopper, it is preferable to prevent oxidative decomposition and the like under vacuum, reduced pressure, or inert gas atmosphere. Tm is the temperature of the die exit portion of the extruder.

  When foreign matter such as scratches or plasticizer aggregates adheres to the die, streak-like defects may occur. Such defects are also referred to as die lines, but in order to reduce surface defects such as die lines, it is preferable to have a structure in which the resin retention portion is minimized in the piping from the extruder to the die. . It is preferable to use a die that has as few scratches as possible inside the lip.

  The inner surface that contacts the molten resin such as an extruder or a die is preferably subjected to surface treatment that makes it difficult for the molten resin to adhere to the surface by reducing the surface roughness or using a material having a low surface energy. Specifically, a hard chrome plated or ceramic sprayed material is polished so that the surface roughness is 0.2 S or less.

  There is no particular limitation on the cooling roll, but it is a roll having a structure in which a heat medium or a coolant body in which the temperature can be controlled flows with a high-rigidity metal roll, the size of which is not limited, but a melt-extruded film The diameter of the cooling roll is usually about 100 mm to 1 m.

  Examples of the surface material of the cooling roll include carbon steel, stainless steel, aluminum, and titanium. Further, in order to increase the hardness of the surface or improve the releasability from the resin, it is preferable to perform a surface treatment such as hard chrome plating, nickel plating, amorphous chrome plating, or ceramic spraying.

  The surface roughness of the chill roll surface is preferably 0.1 μm or less in terms of Ra, and more preferably 0.05 μm or less. The smoother the roll surface, the smoother the surface of the resulting film. Of course, it is preferable that the surface processed is further polished to have the above-described surface roughness.

  Examples of the elastic touch roll according to the present invention include JP-A-03-124425, JP-A-08-224772, JP-A-07-1000096, JP-A-10-272676, WO97 / 028950, JP-A-11-235747, A silicon rubber roll coated with a thin-film metal sleeve can be used as described in JP-A-2002-36332, JP-A-2005-172940, and JP-A-2005-280217.

  When peeling the film from the cooling roll, it is preferable to control the tension to prevent deformation of the film.

  The film obtained as described above is preferably stretched by a stretching operation after passing through the step of contacting the cooling roll.

  As a method of stretching, a known roll stretching machine or tenter can be preferably used. The stretching temperature is usually preferably performed in the temperature range of Tg to Tg + 60 ° C. of the resin constituting the film.

  Prior to winding, the ends may be slit and cut to the width of the product, and knurling (embossing) may be applied to both ends to prevent sticking or scratching during winding. The knurling method can process a metal ring having an uneven pattern on its side surface by heating or pressing. In addition, since the film has deform | transformed and cannot use as a product normally, the holding | grip part of the clip of both ends of a film is cut out and reused.

[Solution casting film forming method]
<Organic solvent>
An organic solvent useful for forming a dope when an optical film is produced by a solution casting method can be used without limitation as long as it dissolves cellulose ester and other additives simultaneously.

  For example, as the chlorinated organic solvent, methylene chloride, as the non-chlorinated organic solvent, methyl acetate, ethyl acetate, amyl acetate, acetone, tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, cyclohexanone, ethyl formate, 2,2,2-trifluoroethanol, 2,2,3,3-hexafluoro-1-propanol, 1,3-difluoro-2-propanol, 1,1,1,3,3,3-hexafluoro- Examples include 2-methyl-2-propanol, 1,1,1,3,3,3-hexafluoro-2-propanol, 2,2,3,3,3-pentafluoro-1-propanol, and nitroethane. Methylene chloride, methyl acetate, ethyl acetate and acetone can be preferably used.

  In addition to the organic solvent, the dope preferably contains 1 to 40% by mass of a linear or branched aliphatic alcohol having 1 to 4 carbon atoms. When the proportion of alcohol in the dope increases, the web gels and peeling from the metal support becomes easy. When the proportion of alcohol is small, thermoplastic acrylic resins and cellulose ester resins in non-chlorine organic solvent systems There is also a role of promoting dissolution of the.

  In particular, in a solvent containing methylene chloride and a linear or branched aliphatic alcohol having 1 to 4 carbon atoms, at least 15 types of thermoplastic acrylic resin, cellulose ester resin, and acrylic particles are used. A dope composition in which 45% by mass is dissolved is preferable.

  Examples of the linear or branched aliphatic alcohol having 1 to 4 carbon atoms include methanol, ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol, and tert-butanol. Ethanol is preferred because of the stability of these dopes, the relatively low boiling point, and good drying properties.

<Solution casting method>
In the production of an optical film by the solution casting method, a step of preparing a dope by dissolving a cellulose ester and an additive in a solvent, a step of casting the dope on a belt-shaped or drum-shaped metal support, a cast dope It is performed by the process of drying as a web, the process of peeling from a metal support, the process of extending | stretching or maintaining width, the process of drying further, and the process of winding up the finished film.

  The concentration of the cellulose ester and the additive in the dope is preferably higher because the drying load after casting on the metal support can be reduced. However, if the concentration of the cellulose ester is too high, the load during filtration increases. Thus, the filtration accuracy is deteriorated. As a density | concentration which makes these compatible, 10-35 mass% is preferable, More preferably, it is 15-25 mass%.

  The metal support in the casting (casting) step 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 set to −50 ° C. to a temperature at which the solvent boils and does not foam. A higher temperature is preferred because the web can be dried faster, but if it is too high, the web may foam or the flatness may deteriorate.

  The preferable support temperature is appropriately determined at 0 to 100 ° C, and more preferably 5 to 30 ° 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 warm 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 using warm air, considering the temperature drop of the web due to the latent heat of vaporization of the solvent, while using warm air above the boiling point of the solvent, there may be cases where wind at a temperature higher than the target temperature is used while preventing foaming. .

  In particular, it is preferable to perform drying efficiently by changing the temperature of the support and the temperature of the drying air during the period from casting to peeling.

  In order for the optical film to exhibit good flatness, the residual solvent amount when peeling the web from the metal support is preferably 10 to 150% by mass, more preferably 20 to 40% by mass or 60 to 130% by mass. Yes, and particularly preferably 20 to 30% by mass or 70 to 120% by mass.

  The amount of residual solvent is defined by the following formula.

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

  Further, in the optical film drying step, the web is peeled off from the metal support and further dried, and the residual solvent amount is preferably 1% by mass or less, more preferably 0.1% by mass or less, particularly Preferably it is 0-0.01 mass% or less.

  In the film drying process, generally, a roll drying method (a method in which a plurality of rolls arranged on the upper and lower sides are alternately passed through and dried) or a method of drying while transporting the web by a tenter method is adopted.

<Physical properties of optical film>
The optical film according to the present invention is preferably a “film that does not cause ductile fracture”. Here, the ductile fracture is a fracture caused by applying a stress larger than the strength of a certain material, and is defined as a fracture accompanied by significant elongation or drawing of the material until the final fracture. The fracture surface is characterized by numerous indentations called dimples.

  Whether or not the film is “a film in which ductile fracture does not occur” is evaluated based on the fact that breakage such as breakage is not observed even when a large stress is applied to bend the film in two.

  In addition to the increasing size of liquid crystal display devices and the increasing brightness of backlight light sources, the use of digital signage and other outdoor applications demands higher brightness. If the tension softening point of the optical film according to the present invention is 105 ° C. to 145 ° C., it can be determined that the film has sufficient heat resistance, and is particularly preferable. It is preferable to control to 110 to 130 ° C.

  As a specific method of measuring the tension softening point, for example, using a Tensilon tester (ORIENTEC, RTC-1225A), the optical film is cut out at 120 mm (length) × 10 mm (width) and pulled with a tension of 10 N. However, the temperature can be continuously increased at a temperature increase rate of 30 ° C./min, and the temperature at 9 N can be measured three times, and the average value can be obtained.

  From the viewpoint of heat resistance, the optical film preferably has a glass transition temperature (Tg) of 110 ° C. or higher. More preferably, it is 120 ° C. or higher. Especially preferably, it is 150 degreeC or more.

  In addition, the glass transition temperature here is the intermediate | middle calculated | required according to JISK7121 (1987), using the differential scanning calorimeter (DSC-7 type | mold by Perkin Elmer), measured with the temperature increase rate of 20 degree-C / min. Point glass transition temperature (Tmg).

  In addition, when an optical film is used as a protective film for a polarizing plate of a liquid crystal display device, unevenness or a change in retardation value occurs due to a dimensional change due to moisture absorption, causing problems such as a decrease in contrast and uneven color. In particular, the above problem becomes significant when the polarizing plate protective film is used in a liquid crystal display device used outdoors. For this reason, the dimensional change rate (%) is preferably less than 0.5%, and more preferably less than 0.3%.

  Further, the optical film preferably has a defect with a diameter of 5 μm or more in the film plane of 1 piece / 10 cm square or less. More preferably, it is 0.5 piece / 10 cm square or less, more preferably 0.1 piece / 10 cm square or less.

  Here, the diameter of the defect indicates the diameter when the defect is circular, and when the defect is not circular, the range of the defect is determined by observing with a microscope by the following method, and the maximum diameter (diameter of circumscribed circle) is determined.

  The range of the defect is the size of the shadow when the defect is observed with the transmitted light of the differential interference microscope when the defect is a bubble or a foreign object. When the defect is a change in the surface shape, such as transfer of a roll flaw or an abrasion, the size is confirmed by observing the defect with the reflected light of a differential interference microscope.

  In addition, when observing with reflected light, if the size of the defect is unclear, aluminum or platinum is deposited on the surface for observation.

  In order to obtain a film having excellent quality expressed by such a defect frequency with high productivity, it is necessary to filter the polymer solution with high precision immediately before casting, to increase the cleanliness around the casting machine, It is effective to set drying conditions after rolling stepwise and to dry efficiently while suppressing foaming.

  When the number of defects is greater than 1/10 cm square, for example, when the film is tensioned during processing in a later process, the film may break with the defects as a starting point, and productivity may decrease. Moreover, when the diameter of a defect becomes 5 micrometers or more, it can confirm visually by polarizing plate observation etc., and when used as an optical member, a bright spot may arise.

  Moreover, even when it cannot be visually confirmed, when a hard coat layer or the like is formed on the film, the coating agent may not be formed uniformly, resulting in a defect (missing coating). Here, the defect is a void in the film (foaming defect) generated due to the rapid evaporation of the solvent in the drying process of the solution casting, a foreign matter in the film forming stock solution, or a foreign matter mixed in the film forming. This refers to the foreign matter (foreign matter defect) in the film.

  Further, the optical film preferably has a breaking elongation in at least one direction of 10% or more, more preferably 20% or more, in the measurement based on JIS-K7127-1999.

  The upper limit of the elongation at break is not particularly limited, but is practically about 250%.

  The thickness of the optical film is preferably 20 μm or more. More preferably, it is 30 μm or more.

  The upper limit of the thickness is not particularly limited, but in the case of forming a film by a solution casting method, the upper limit is about 250 μm from the viewpoint of applicability, foaming, solvent drying, and the like. In addition, the thickness of a film can be suitably selected according to a use.

  The optical film preferably has a total light transmittance of 90% or more, more preferably 93% or more. Moreover, as a realistic upper limit, it is about 99%. In order to achieve excellent transparency expressed by such total light transmittance, it is necessary not to introduce additives and copolymerization components that absorb visible light, or to remove foreign substances in the polymer by high-precision filtration. It is effective to reduce the diffusion and absorption of light inside the film.

  Also, reduce the surface roughness of the film surface by reducing the surface roughness of the film contact part (cooling roll, calender roll, drum, belt, coating substrate in solution casting, transport roll, etc.) during film formation. It is also effective to reduce the diffusion and reflection of light on the film surface by reducing the refractive index of the thermoplastic acrylic resin.

<Reply material suitability>
In the process of making an optical film from a conventional cellulose ester, a process of appropriately slitting both end portions of the film is provided, and unnecessary end films appearing at that time are reused. This is generally called return material.

  In solution casting film formation, a slit film is dissolved again in a solvent at a relatively low temperature, so that the properties equivalent to those of a new raw material can be maintained.

  Even if the optical film using the cellulose ester according to the present invention was used as a return material in solution casting film formation, there was no problem as in the prior art.

  On the other hand, with a melt cast film, it is difficult to make full use of recycled materials like a solution cast film. That is, in the melt casting film forming process, since high-temperature heat is applied to the cellulose ester at the time of melting, the cellulose ester molecules have been deteriorated and decomposed, and when reused, the decomposition and deterioration further proceed. Components that adversely affect the film for optical use such as a deteriorated product, a gel foreign material, and a bright spot foreign material are likely to be generated, and the recycled material has not been actually used.

  However, since the cellulose ester according to the present invention is extremely uniform and has few impurities, even if the film obtained by melt casting is used again as a recycled material, there is little generation and coloring of deteriorated products, It was found that the quality of the optical application film was sufficiently achieved.

  The use ratio of the recycled material is preferably 0 to 70% by mass, more preferably 10 to 50% by mass, and further preferably 20 to 40% by mass with respect to the solid content of the main unused raw material.

  When using recycled materials, the amount of additives contained in the optical film, such as plasticizers, UV absorbers, and fine particles, is reduced according to the amount used, so that the final optical film composition becomes the design value. Adjustment is preferably performed.

<Functional layer>
The optical film according to the present invention can be provided with functional layers such as an antistatic layer, a backcoat layer, an antireflection layer, a slippery layer, an adhesive layer, an antiglare layer, and a barrier layer.

<Hard coat layer>
The hard coat layer used in the present invention contains an actinic radiation curable resin, and is a layer mainly composed of a resin that cures through a crosslinking reaction by irradiation with an actinic ray (also referred to as an active energy ray) such as an ultraviolet ray or an electron beam. Preferably there is.

  As the actinic radiation curable resin, a component containing a monomer having an ethylenically unsaturated double bond is preferably used, and an actinic radiation curable resin layer is formed by curing by irradiation with actinic radiation such as ultraviolet rays or electron beams. The

  Typical examples of the actinic radiation curable resin include an ultraviolet curable resin and an electron beam curable resin, but the resin that is cured by ultraviolet irradiation is excellent in mechanical film strength (abrasion resistance, pencil hardness). preferable.

  As the ultraviolet curable resin, for example, an ultraviolet curable urethane acrylate resin, an ultraviolet curable polyester acrylate resin, an ultraviolet curable epoxy acrylate resin, an ultraviolet curable polyol acrylate resin, or an ultraviolet curable epoxy resin is preferable. Used. Of these, ultraviolet curable acrylate resins are preferred.

  Or it is preferable to contain a photoinitiator in a docoat layer in order to accelerate | stimulate hardening of actinic radiation curable resin. The amount of the photopolymerization initiator is preferably contained in a mass ratio of photopolymerization initiator: active ray curable resin = 20: 100 to 0.01: 100.

  Specific examples of the photopolymerization initiator include acetophenone, benzophenone, hydroxybenzophenone, Michler's ketone, α-amyloxime ester, thioxanthone, and derivatives thereof, but are not particularly limited thereto.

  Alternatively, the docoat layer preferably contains fine particles of an inorganic compound or an organic compound.

  As inorganic fine particles, silicon oxide, titanium oxide, aluminum oxide, tin oxide, indium oxide, ITO, zinc oxide, zirconium oxide, magnesium oxide, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated silicic acid Mention may be made of calcium, aluminum silicate, magnesium silicate and calcium phosphate. In particular, silicon oxide, titanium oxide, aluminum oxide, zirconium oxide, magnesium oxide and the like are preferably used.

  As organic particles, polymethacrylic acid methyl acrylate resin powder, acrylic styrene resin powder, polymethyl methacrylate resin powder, silicon resin powder, polystyrene resin powder, polycarbonate resin powder, benzoguanamine resin powder, melamine resin powder, A polyolefin resin powder, a polyester resin powder, a polyamide resin powder, a polyimide resin powder, a polyfluoroethylene resin powder, or the like can be added.

  The average particle size of these fine particle powders is not particularly limited, but is preferably 0.01 to 5 μm, and more preferably 0.01 to 1.0 μm. Moreover, you may contain 2 or more types of microparticles | fine-particles from which a particle size differs. The average particle diameter of the fine particles can be measured by, for example, a laser diffraction particle size distribution measuring device.

  The ratio of the ultraviolet curable resin composition and the fine particles is desirably 10 to 400 parts by mass, more preferably 50 to 200 parts by mass with respect to 100 parts by mass of the resin composition.

  These hard coat layers are coated using a known method such as a gravure coater, dip coater, reverse coater, wire bar coater, die coater, ink jet method, and the like. And can be formed by UV curing.

  The dry thickness of the hard coat layer is an average film thickness of 0.1 to 30 μm, preferably 1 to 20 μm, particularly preferably 6 to 15 μm.

  As a light source for UV curing treatment, any light source that generates ultraviolet rays can be used without limitation. For example, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a carbon arc lamp, a metal halide lamp, a xenon lamp, or the like can be used.

Irradiation conditions vary depending on each lamp, but the irradiation amount of active rays is usually 5 to 500 mJ / cm ² , preferably 5 to 200 mJ / cm ² .

<Back coat layer>
In the optical film according to the present invention, a back coat layer may be provided on the surface opposite to the side on which the hard coat layer is provided to prevent curling and sticking.

  As particles added to the back coat layer, examples of inorganic compounds include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, tin oxide, and oxidation. Mention may be made of indium, zinc oxide, ITO, hydrated calcium silicate, aluminum silicate, magnesium silicate and calcium phosphate.

  The particles contained in the backcoat layer are preferably 0.1 to 50% by mass with respect to the binder. When the back coat layer is provided, the increase in haze is preferably 1.5% or less, more preferably 0.5% or less, and particularly preferably 0.1% or less.

  As the binder, a cellulose ester resin such as diacetylcellulose is preferable.

<Antireflection layer>
The optical film according to the present invention can be used as an antireflection film having an antireflection function for external light by coating an antireflection layer on the hard coat layer.

  The antireflection layer is preferably laminated in consideration of the refractive index, the film thickness, the number of layers, the layer order, and the like so that the reflectance is reduced by optical interference. The antireflection layer is preferably composed of a low refractive index layer having a refractive index lower than that of the support, or a combination of a high refractive index layer having a refractive index higher than that of the support and a low refractive index layer. Particularly preferably, it is an antireflection layer composed of three or more refractive index layers. Three layers having different refractive indexes from the support side are divided into medium refractive index layers (high refractive index layers having a higher refractive index than the support). Are preferably laminated in the order of a layer having a lower refractive index) / a high refractive index layer / a low refractive index layer. Alternatively, an antireflection layer having a layer structure of four or more layers in which two or more high refractive index layers and two or more low refractive index layers are alternately laminated is also preferably used.

  As the layer structure of the antireflection film, the following structure is conceivable, but is not limited thereto.

Optical film / hard coat layer / low refractive index layer Optical film / hard coat layer / medium refractive index layer / low refractive index layer Optical film / hard coat layer / medium refractive index layer / high refractive index layer / low refractive index layer Optical film / Hard coat layer / High refractive index layer (conductive layer) / Low refractive index layer Optical film / Hard coat layer / Anti-glare layer / Low refractive index layer The low refractive index layer essential for the antireflection film is silica. The fine particles are preferably contained, and the refractive index thereof is lower than the refractive index of the cellulose film as the support, and is preferably in the range of 1.30 to 1.45 at 23 ° C. and a wavelength of 550 nm.

  The film thickness of the low refractive index layer is preferably 5 nm to 0.5 μm, more preferably 10 nm to 0.3 μm, and most preferably 30 nm to 0.2 μm.

  The composition for forming a low refractive index layer preferably contains at least one kind of particles having an outer shell layer and porous or hollow inside as silica-based fine particles. In particular, the particles having the outer shell layer and porous or hollow inside are preferably hollow silica-based fine particles.

  The composition for forming a low refractive index layer may contain an organosilicon compound represented by the following general formula (OSi-1) or a hydrolyzate thereof, or a polycondensate thereof.

General formula (OSi-1): Si (OR) ₄
In the organic silicon compound represented by the general formula, R represents an alkyl group having 1 to 4 carbon atoms. Specifically, tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane and the like are preferably used.

  In addition, a silane coupling agent, a curing agent, a surfactant and the like may be added as necessary.

<Polarizing plate>
A polarizing plate using the optical film according to the present invention will be described. The polarizing plate can be produced by a general method. The back side of the optical film according to the present invention is subjected to alkali saponification treatment, and the treated optical film is attached to at least one surface of a polarizing film produced by immersing and stretching in an iodine solution using a completely saponified polyvinyl alcohol aqueous solution. It is preferable to match.

  The optical film may be used on the other surface, or another polarizing plate protective film may be used. For example, a non-oriented film having retardation Ro described in JP-A-2003-12859 of 0 to 5 nm at 590 nm and Rt of -20 to +20 nm can be mentioned as an example.

  In addition, an optical compensation film (retardation film) having a retardation of in-plane retardation Ro of 590 nm, 20 to 70 nm, and Rt of 70 to 400 nm may be used as a polarizing plate capable of widening the viewing angle. it can. These can be produced, for example, by the method of JP-A-2002-71957. Alternatively, it is preferable to use an optical compensation film having an optical anisotropic layer formed by aligning a liquid crystal compound such as a discotic liquid crystal. For example, the optically anisotropic layer can be formed by the method described in JP-A-2003-98348.

  Moreover, as a commercially available polarizing plate protective film preferably used, KC8UX2MW, KC4UX, KC5UX, KC4UY, KC8UY, KC12UR, KC4UEW, KC8UCR-3, KC8UCR-4, KC8UCR-5, KC4FR-1, KC4FR-2, KC4FR-2, KC8FR-2 KC4UE (Konica Minolta Opto Co., Ltd.) etc. are mentioned.

  The polarizing film, which is the main component of the polarizing plate, is an element that transmits only light having a polarization plane in a certain direction. A typical polarizing film known at present is a polyvinyl alcohol polarizing film, which is a polyvinyl alcohol film. There are ones in which iodine is dyed on a system film and ones in which a dichroic dye is dyed, but it is not limited to this.

  As the polarizing film, a polyvinyl alcohol aqueous solution is formed and dyed by uniaxially stretching or dyed, or uniaxially stretched after dyeing, and then preferably subjected to a durability treatment with a boron compound. A polarizing film having a thickness of 5 to 30 μm, preferably 8 to 15 μm, is preferably used.

  On the surface of the polarizing film, one side of the optical film according to the present invention is bonded to form a polarizing plate. Preferably, it is pasted with an aqueous adhesive mainly composed of completely saponified polyvinyl alcohol or the like.

<Liquid crystal display device>
By incorporating a polarizing plate produced using the optical film according to the present invention into a display device, various image display devices with excellent visibility can be produced.

  The optical film according to the present invention is incorporated in a polarizing plate, and is a reflection type, transmission type, transflective liquid crystal display device or TN type, STN type, OCB type, HAN type, VA type (PVA type, MVA type), IPS type. It is preferably used in liquid crystal display devices of various driving systems such as OCB type.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. “Part” described below represents “part by mass”.

  Hereinafter, the used cellulose ester is shown below.

Cellulose ester A: cellulose acetate propionate having an acetyl substitution degree of 0.2, a propionyl substitution degree of 2.55, and a total acyl group substitution degree of 2.75 (Mw = 246,000, Mw / Mn = 3.6)
Cellulose ester B: cellulose acetate propionate having an acetyl substitution degree of 1.63, a propionyl substitution degree of 1.19 and a total acyl group substitution degree of 2.82 (Mw = 229,000, Mw / Mn = 2.9)
Cellulose ester C: cellulose diacetate having an acetyl substitution degree of 2.42 (Mw = 170,000, Mw / Mn = 3.2)
<Comparative Synthesis Example 1>
45 g of cellulose ester A was added to 225 ml of acetic acid, and dissolved by stirring at 25 ° C. At 25 ° C., a mixed solution of 45 ml of acetic acid and 180 ml of water was added dropwise over 2 hours. After completion of dropping, the mixture was stirred at 25 ° C. for 1 hour, and the precipitated granular solid was filtered. After washing with pure water until the pH of the filtrate reached 7, it was dried at 60 ° C. to obtain 44.0 g of comparative cellulose ester (D-1).

<Comparative Synthesis Example 2>
45 g of cellulose ester A was added to 225 ml of acetic acid and dissolved by heating at 50 ° C. While maintaining the internal temperature in the range of 48 to 50 ° C., a mixed solution of 45 ml of acetic acid and 180 ml of water was added dropwise over 2 hours. After completion of the dropping, the temperature was lowered to 25 ° C. over 1 hour, and the precipitated granular solid was filtered. After washing with pure water until the pH of the filtrate reached 7, it was dried at 60 ° C. to obtain 41.0 g of a comparative cellulose ester (D-2).

<Comparative Synthesis Example 3>
50 ml of methanol was added to 10 g of cellulose ester A, and further 50 ml of acetone was added and dissolved while stirring at 25 ° C. After dropping 150 ml of methanol over 30 minutes at 25 ° C., the mixture was stirred at 25 ° C. for 1 hour. The solution after stirring was white turbid with a small amount of powder, the filterability was very poor, and the desired cellulose ester could not be obtained.

<Comparative Synthesis Example 4>
To a mixed solution of 50 ml of acetone, 50 ml of methanol and 20 ml of water, 10 g of cellulose ester B was added and dissolved by heating at 50 ° C. While maintaining the internal temperature in the range of 48 to 50 ° C., a mixture of 30 ml of acetone and 30 ml of water was added dropwise over 30 minutes. After completion of dropping, the temperature was lowered to 25 ° C. over 30 minutes, and the precipitated solid was filtered. The obtained solid was dried at 60 ° C., thereby obtaining 8.7 g of a comparative cellulose ester (D-3).

<Comparative Synthesis Example 5>
200 ml of acetic acid was added to 10 g of cellulose ester B, and the mixture was stirred and dissolved at 25 ° C. to prepare a cellulose ester solution. While maintaining the temperature at 25 ° C., the prepared cellulose ester solution was dropped into a mixed solution of 300 ml of acetic acid and 2000 ml of water over 10 minutes, and stirred at 25 ° C. for 1 hour after the completion of the dropping. The obtained solid was collected by filtration, washed with water until the pH of the filtrate reached 7, and then dried at 60 ° C. to obtain 9.9 g of comparative cellulose ester (D-4).

<Comparative Synthesis Example 6>
10 g of cellulose ester A was added to 100.0 ml of ethyl acetate and dissolved by stirring at room temperature. The cellulose ester solution was cooled to 5 ° C., and 1000 ml of methanol was added dropwise over 1 hour, but almost no solid precipitation was observed.

<Comparative Synthesis Example 7>
(Activation process)
The activation process was performed in two stages.

  First-stage activation step: Raw material: 296.4 g of acetic acid as a pretreatment agent is sprayed on 423.6 g of cotton linter pulverized product (water content 33.6 g), and left at 25 ° C. for 16 hours. First stage pretreatment was performed.

  Second stage activation step: A mixture of 123.4 g of acetic acid and 3.82 g of sulfuric acid is sprayed on the processed product after the activation process of the first stage and allowed to stand at 25 ° C. for 45 minutes. The activation treatment was performed.

(Acylation step)
An acylation reaction was carried out by adding an acylation solvent, an acylating agent and an acylation catalyst having the following composition to the treated product after the activation step.
Acylation solvent: 6.7 g of acetic acid, 3543.5 g of propionic acid
Acylating agent: 288.1 g of acetic anhydride, 2692.7 g of propionic anhydride
Acylation catalyst: 32.0 g of sulfuric acid
The reaction solvent, reaction reagent, and reaction catalyst were mixed and cooled in advance, and the pretreated raw material was added to start the reaction. After maintaining at 10 ° C. or lower for 60 minutes, the temperature was raised to 35 ° C. over 60 minutes, and acylation was performed by holding at 35 ° C. for 150 minutes.

(Step of stopping acylation reaction)
Three hours after the start of the reaction, 1637.8 g of acetic acid and 756.1 g of water were added to the reaction solution to neutralize the reaction reagent (anhydride), and the aging process was started.

(Aging process)
After neutralization of the acylating agent, the aging reaction was started. The reaction vessel was heated to 60 ° C. and held for 275 minutes.

(Aging reaction stop process)
The neutralization of the reaction catalyst was performed in multiple stages (two stages). In the first stage, 2785.5 g of acetic acid, 28.4 g of water, and 118.0 g of 24% magnesium acetate aqueous solution were added. After 30 minutes, the second stage (306.7 g of acetic acid and 306.7 g of 24% magnesium acetate aqueous solution) was added. Finished the reaction. A viscous liquid was obtained as a reaction product.

(Filtration process)
It filtered with the pressure of 0.20 Mpa using the metal pressure filter which put 200 g of viscous liquid obtained as a reaction product. As the filter, a sintered metal filter (Nippon Seisen Co., Ltd., Finepore product number NF-06N, display pore size: 5 μm) was used.

(Precipitation / washing / drying process)
Precipitation: After kneading 300 parts by mass of 70% aqueous acetic acid with respect to 100 parts by mass of the dope, 100 parts by mass of 30% aqueous acetic acid is added to precipitate reactive organisms. Thereafter, 200 parts by mass of water was added, and the product was solidified by maintaining at room temperature or higher for 30 minutes.
Washing: Water is added to the drained precipitation cake, the temperature is raised to 80 ° C., and batch processing is performed for 60 minutes. Thereafter, washing with a large amount of water was performed for 2 hours with stirring.
Stabilization: It was immersed in an aqueous calcium hydroxide solution having a concentration of 30 ppm at room temperature for 30 minutes, and spin-dehydrated.
Drying: A comparative cellulose acetate propionate (D-5) having an acetyl substitution degree of 1.12, a propionyl substitution degree of 1.59 and a polymerization degree of 181 was obtained by air drying at 80 ° C.

<Comparative Synthesis Example 8>
10 parts by mass of cellulose (hardwood pulp) and 5 parts by mass of acetic acid were placed in a reaction vessel and kept at 25 ° C. for 1 hour (pretreatment). The reaction vessel was cooled to 0 ° C., and separately prepared a mixture of 103 parts by weight of propionic anhydride and 1.0 part by weight of sulfuric acid, cooled to −10 ° C., and then added to the pretreated cellulose at once. It was. After 30 minutes, the external temperature was raised to 30 ° C. and reacted for 4 hours. The reaction vessel was cooled in an ice water bath at 5 ° C., and 120 parts by mass of 25% aqueous acetic acid was added over 30 minutes. The internal temperature was raised to 60 ° C. and stirred for 2 hours. 10 parts by mass of a 50% aqueous solution of magnesium acetate tetrahydrate was added and stirred for 30 minutes.

  75 parts by mass of 25% aqueous acetic acid and 250 parts by mass of water were gradually added to precipitate cellulose acetate propionate. After washing with warm water at 70 ° C. until the pH of the washing solution reached 6-7, the mixture was stirred for 0.5 hour in a 0.001% aqueous calcium hydroxide solution and filtered. A cellulose acetate propionate having an acetyl substitution degree of 0.16, a propionyl substitution degree of 2.55 and a weight average molecular weight of 135,000 was obtained.

  100 parts by mass of the obtained cellulose acetate propionate and 2000 parts by mass of acetic acid were mixed and stirred at 40 ° C. to prepare a uniform solution. Celite 545 (manufactured by Celite) was added to this solution by 10% by mass with respect to the mass of the solution and stirred for 1 hour, and then a cellulose fiber filter paper (retained particle size 40 μm), a sintered metal filter (retained particle size 10 μm), metal Foreign matter was removed by pressure filtration in order with a sintered filter (retained particle size 10 μm). Furthermore, 75 parts by mass of 25% aqueous acetic acid and 250 parts by mass of water were gradually added to precipitate cellulose acetate propionate. After washing with hot water at 70 ° C. until the pH of the washing solution reached 6-7, the mixture was stirred in 0.001% calcium hydroxide aqueous solution for 0.5 hour. After filtration, it was dried at 70 ° C. to obtain a comparative cellulose acetate propionate (D-6) having an acetyl substitution degree of 0.16, a propionyl substitution degree of 2.55, and a weight average molecular weight of 134,000.

<Comparative Synthesis Example 9>
(Activation process)
The activation process was performed in two stages.
First-stage activation step: Raw material: 296.4 g of acetic acid is sprayed as a pretreatment agent on 424.1 g (of which moisture is 34.1 g) of raw material of cotton linter. The first stage pretreatment was carried out by standing at 25 ° C. for 16 hours.
Second stage activation step: A mixture of 123.4 g of acetic acid and 3.82 g of sulfuric acid is sprayed on the processed product after the activation process of the first stage and allowed to stand at 25 ° C. for 45 minutes. The activation treatment was performed.

(Acylation step)
An acylation reaction was carried out by adding an acylation solvent, an acylating agent and an acylation catalyst having the following composition to the treated product after the activation step.
Acylation solvent: Acetic acid 943.5 g, Butyric acid 1851.9 g
Acylating agent: 3724.5 g of butyric anhydride
Acylation catalyst: 42.35 g of sulfuric acid
The above amounts of acylating solvent, acylating agent, and acylating catalyst were mixed and cooled in advance, and a pretreated material cellulose pretreated was added to initiate the reaction. After maintaining at 10 ° C. or lower for 50 minutes, the temperature was raised to 30 ° C. over 20 minutes and held at 30 ° C. for 130 minutes to carry out an acylation reaction.

(Step of stopping acylation reaction)
At 200 minutes from the start of the reaction, 112.4 g of acetic acid and 458.3 g of water were added to the reaction solution to neutralize the acylating agent (anhydride).

(Aging process)
After neutralization of the acylating agent, the aging reaction was started. The reaction vessel was heated to 60 ° C. and held for 240 minutes.

(Aging reaction stop process)
The neutralization of the reaction catalyst was performed in multiple stages (two stages). In the first stage, 2565.2 g of acetic acid, 118.9 g of water and 179.3 g of 24% magnesium acetate aqueous solution were added, and 30 minutes later, the second stage (126.9 g of acetic acid, 126.9 g of 24% magnesium acetate aqueous solution) was added. To complete the reaction. A viscous liquid was obtained as a reaction product.

(Filtration process)
The reaction product was filtered at a pressure of 0.20 MPa using a metal pressure filter containing 200 g of the reaction product. As the filter, a sintered metal filter (Nippon Seisen Co., Ltd., Finepore product number NF-06N, display pore size: 5 μm) was used.

(Precipitation / washing / drying process)
Precipitation: After kneading 300 parts by mass of 70% aqueous acetic acid with respect to 100 parts by mass of the dope, 100 parts by mass of 30% aqueous acetic acid is added to precipitate reactive organisms. Thereafter, 200 parts by mass of water was added, and the product was solidified by maintaining at room temperature or higher for 30 minutes.
Washing: Water is added to the drained precipitation cake, the temperature is raised to 80 ° C., and batch processing is performed for 60 minutes. Thereafter, washing with a large amount of water was performed for 2 hours with stirring.
Stabilization: It was immersed in an aqueous calcium hydroxide solution having a concentration of 30 ppm at room temperature for 30 minutes, and spin-dehydrated.
Drying: A comparative cellulose acetate butyrate (D-7) having an acetyl substitution degree of 0.66, a butyryl substitution degree of 2.12, and a polymerization degree of 151 was obtained by air drying at 80 ° C.

<Synthesis Example 1>
After adding 200 ml of methanol to 10.0 g of cellulose ester B, 100 ml of THF was added and dissolved by stirring at 25 ° C. for 30 minutes. A mixed solution of 100 ml of methanol and 100 ml of pure water was added dropwise at 25 ° C. over 30 minutes, followed by stirring at 25 ° C. for 1 hour. The precipitated granular solid was filtered and then dried at 60 ° C. to obtain 8.0 g of cellulose ester (P-1).

<Synthesis Example 2>
To 25 g of cellulose ester A were added 45 ml of acetone, 67.5 ml of methanol, and 12.5 ml of pure water, and the mixture was stirred at 50 ° C. and dissolved by heating. A mixed solution of 70 ml of acetone, 105 ml of methanol, and 75 ml of pure water was dropped while maintaining the internal temperature in the range of 47 to 50 ° C. After completion of dropping, the mixture is stirred at 50 ° C. for 1 hour and then cooled to 25 ° C. over 1 hour. The precipitated granular solid was filtered, and the obtained solid was washed with 60 ml of methanol and then blown and dried at 60 ° C. to obtain 23.2 g of cellulose ester (P-2).

<Synthesis Example 3>
Methanol 125 ml and acetone 125 ml were sequentially added to 25 g of cellulose ester B, and dissolved by stirring at 25 ° C. A mixed solution of 130 ml of acetone, 130 ml of methanol and 219 ml of pure water was added dropwise at 25 ° C. over 30 minutes. After completion of dropping, the mixture was stirred at 25 ° C. for 1 hour, and then the precipitated granular solid was filtered. The obtained solid was washed with 60 ml of methanol and then blown and dried at 60 ° C. to obtain 23.0 g of cellulose ester (P-3).

<Synthesis Example 4>
To 10 g of cellulose ester A, 100 ml of acetic acid was added and stirred at 25 ° C. to dissolve. A mixture of 80 ml of acetic acid and 120 ml of water was added dropwise at 25 ° C. over 40 minutes. After completion of dropping, the mixture was stirred at 25 ° C. for 1 hour, and then the precipitated granular solid was filtered. After washing with water until the pH of the filtrate reached 7, it was dried at 60 ° C. to obtain 9.8 g of cellulose ester (P-4).

<Synthesis Example 5>
To 10 g of cellulose ester A, 100 ml of acetic acid was added and stirred at 25 ° C. to dissolve. A mixture of 100 ml of acetic acid and 100 ml of water was added dropwise at 25 ° C. over 30 minutes, followed by stirring at 25 ° C. for 1 hour. Further, a mixed solution of 100 ml of acetic acid and 100 ml of water was added dropwise at 25 ° C. over 30 minutes, and then stirred at 25 ° C. for 1 hour. The precipitated granular solid was filtered, washed with water until the pH of the filtrate reached 7, and then dried at 60 ° C. to obtain 9.5 g of cellulose ester (P-5).

<Synthesis Example 6>
10 g of cellulose ester C was added to a mixed solution of 70 ml of methanol and 70 ml of acetone and dissolved by heating at 50 ° C. While maintaining the internal temperature in the range of 47 to 50 ° C., 30 ml of water was slowly added so that the cellulose ester did not precipitate. Next, a mixture of 80 ml of methanol and 80 ml of water was added dropwise over 1 hour while maintaining the internal temperature in the range of 47 to 50 ° C. After completion of the dropwise addition, the temperature was lowered to 25 ° C. over 1 hour, followed by further stirring at 25 ° C. for 1 hour. The precipitated solid was filtered and dried at 60 ° C. to obtain 8.9 g of cellulose ester (P-6).

<Synthesis Example 7>
After adding 100 ml of methanol to 10 g of cellulose ester A, 50 ml of acetic acid was added and stirred at 25 ° C. for 1 hour. A mixture of 50 ml of acetic acid and 120 ml of water was added dropwise at 25 ° C. over 30 minutes, followed by stirring at 25 ° C. for 1 hour. The precipitated granular solid was filtered, washed with water until the pH of the filtrate reached 7, and then dried at 60 ° C. to obtain 9.2 g of cellulose ester (P-7).

<Synthesis Example 8>
After adding 50 ml of ethanol to 10 g of cellulose ester A, 50 ml of acetic acid was added and stirred at 25 ° C. for 1 hour. A mixture of 50 ml of acetic acid and 120 ml of water was added dropwise at 25 ° C. over 30 minutes, followed by stirring at 25 ° C. for 1 hour. The precipitated granular solid was filtered, washed with water until the pH of the filtrate reached 7, and then dried at 60 ° C. to obtain 9.0 g of cellulose ester (P-8).

<Synthesis Example 9>
(Activation process)
The activation process was performed in two stages.
First-stage activation step: Raw material: 296.4 g of acetic acid as a pretreatment agent is sprayed on 423.6 g of cotton linter pulverized product (water content 33.6 g), and left at 25 ° C. for 16 hours. First stage pretreatment was performed.
Second stage activation step: A mixture of 123.4 g of acetic acid and 3.82 g of sulfuric acid is sprayed on the processed product after the activation process of the first stage and allowed to stand at 25 ° C. for 45 minutes. The activation treatment was performed.

(Acylation step)
An acylation reaction was carried out by adding an acylation solvent, an acylating agent and an acylation catalyst having the following composition to the treated product after the activation step.
Acylation solvent: 6.7 g of acetic acid, 3543.5 g of propionic acid
Acylating agent: 288.1 g of acetic anhydride, 2692.7 g of propionic anhydride
Acylation catalyst: 32.0 g of sulfuric acid
The reaction solvent, reaction reagent, and reaction catalyst were mixed and cooled in advance, and the pretreated raw material was added to start the reaction. After maintaining at 10 ° C. or lower for 60 minutes, the temperature was raised to 35 ° C. over 60 minutes, and acylation was performed by holding at 35 ° C. for 150 minutes.

(Step of stopping acylation reaction)
Three hours after the start of the reaction, 1637.8 g of acetic acid and 756.1 g of water were added to the reaction solution to neutralize the reaction reagent (anhydride), and the aging process was started.

(Aging process)
After neutralization of the acylating agent, the aging reaction was started. The reaction vessel was heated to 60 ° C. and held for 275 minutes.

(Aging reaction stop process)
The neutralization of the reaction catalyst was performed in multiple stages (two stages). In the first stage, 2785.5 g of acetic acid, 28.4 g of water, and 118.0 g of 24% magnesium acetate aqueous solution were added. After 30 minutes, the second stage (306.7 g of acetic acid and 306.7 g of 24% magnesium acetate aqueous solution) was added. Finished the reaction. A viscous liquid was obtained as a reaction product.

(Filtration process)
It filtered with the pressure of 0.20 Mpa using the metal pressure filter which put 200 g of viscous liquid obtained as a reaction product. As the filter, a sintered metal filter (Nippon Seisen Co., Ltd., Finepore product number NF-06N, display pore size: 5 μm) was used.

(Precipitation / washing / drying process)
Precipitation: A solution prepared by mixing 240 parts by mass of acetic acid and 360 parts by mass of water was added dropwise at 25 ° C. over 40 minutes with respect to 100 parts by mass of the dope, and stirred for 1 hour while maintaining 25 ° C. after completion of the addition. .
Washing: Water is added to the drained precipitation cake, the temperature is raised to 80 ° C., and batch processing is performed for 60 minutes. Thereafter, washing with a large amount of water was performed for 2 hours with stirring.
Stabilization: It was immersed in an aqueous calcium hydroxide solution having a concentration of 30 ppm at room temperature for 30 minutes, and spin-dehydrated.
Drying: A comparative cellulose acetate propionate (P-9) having an acetyl substitution degree of 1.12, a propionyl substitution degree of 1.59, and a weight average molecular weight of 150,000 was obtained by air drying at 80 ° C.

<Synthesis Example 10>
10 parts by mass of cellulose (hardwood pulp) and 5 parts by mass of acetic acid were placed in a reaction vessel and kept at 25 ° C. for 1 hour (pretreatment). The reaction vessel was cooled to 0 ° C., and separately prepared a mixture of 103 parts by weight of propionic anhydride and 1.0 part by weight of sulfuric acid, cooled to −10 ° C., and then added to the pretreated cellulose at once. It was. After 30 minutes, the external temperature was raised to 30 ° C. and reacted for 4 hours. The reaction vessel was cooled in an ice water bath at 5 ° C., and 120 parts by mass of 25% aqueous acetic acid was added over 30 minutes. The internal temperature was raised to 60 ° C. and stirred for 2 hours. 10 parts by mass of a 50% aqueous solution of magnesium acetate tetrahydrate was added and stirred for 30 minutes.

  75 parts by mass of 25% aqueous acetic acid and 250 parts by mass of water were gradually added to precipitate cellulose acetate propionate. After washing with warm water at 70 ° C. until the pH of the washing solution reached 6-7, the mixture was stirred for 0.5 hour in a 0.001% aqueous calcium hydroxide solution and filtered. A cellulose acetate propionate having an acetyl substitution degree of 0.16, a propionyl substitution degree of 2.55 and a weight average molecular weight of 135,000 was obtained.

  100 parts by mass of the obtained cellulose acetate propionate and 1000 parts by mass of acetic acid were mixed and stirred at 40 ° C. to prepare a uniform solution. Celite 545 (manufactured by Celite) was added to this solution by 10% by mass with respect to the mass of the solution and stirred for 1 hour, and then a cellulose fiber filter paper (retained particle size 40 μm), a sintered metal filter (retained particle size 10 μm), metal Foreign matter was removed by pressure filtration in order with a sintered filter (retained particle size 10 μm). 50 parts by mass of methanol was added to the filtered solution and mixed, and a mixed solution of 500 parts by mass of acetic acid and 1200 parts by mass of water was gradually added to precipitate cellulose acetate propionate. After filtration, washing was performed with warm water at 70 ° C. until the pH of the washing solution became 6 to 7, and the mixture was stirred in a 0.001% aqueous calcium hydroxide solution for 0.5 hour. After filtration, it was dried at 70 ° C. to obtain a comparative cellulose acetate propionate (P-10) having an acetyl substitution degree of 0.16, a propionyl substitution degree of 2.55, and a weight average molecular weight of 134,000.

<Synthesis Example 11>
(Activation process)
The activation process was performed in two stages.
First-stage activation step: Raw material: 296.4 g of acetic acid is sprayed as a pretreatment agent on 424.1 g (of which moisture is 34.1 g) of raw material of cotton linter. The first stage pretreatment was carried out by standing at 25 ° C. for 16 hours.
Second stage activation step: A mixture of 123.4 g of acetic acid and 3.82 g of sulfuric acid is sprayed on the processed product after the activation process of the first stage and allowed to stand at 25 ° C. for 45 minutes. The activation treatment was performed.

(Acylation step)
An acylation reaction was carried out by adding an acylation solvent, an acylating agent and an acylation catalyst having the following composition to the treated product after the activation step.
Acylation solvent: Acetic acid 943.5 g, Butyric acid 1851.9 g
Acylating agent: 3724.5 g of butyric anhydride
Acylation catalyst: 42.35 g of sulfuric acid
The above amounts of acylating solvent, acylating agent, and acylating catalyst were mixed and cooled in advance, and a pretreated material cellulose pretreated was added to initiate the reaction. After maintaining at 10 ° C. or lower for 50 minutes, the temperature was raised to 30 ° C. over 20 minutes and held at 30 ° C. for 130 minutes to carry out an acylation reaction.

(Step of stopping acylation reaction)
At 200 minutes from the start of the reaction, 112.4 g of acetic acid and 458.3 g of water were added to the reaction solution to neutralize the acylating agent (anhydride).

(Aging process)
After neutralization of the acylating agent, the aging reaction was started. The reaction vessel was heated to 60 ° C. and held for 240 minutes.

(Aging reaction stop process)
The neutralization of the reaction catalyst was performed in multiple stages (two stages). In the first stage, 2565.2 g of acetic acid, 118.9 g of water and 179.3 g of 24% magnesium acetate aqueous solution were added, and 30 minutes later, the second stage (126.9 g of acetic acid, 126.9 g of 24% magnesium acetate aqueous solution) was added. To complete the reaction. A viscous liquid was obtained as a reaction product.

(Filtration process)
The reaction product was filtered at a pressure of 0.20 MPa using a metal pressure filter containing 200 g of the reaction product. As the filter, a sintered metal filter (Nippon Seisen Co., Ltd., Finepore product number NF-06N, display pore size: 5 μm) was used.

(Precipitation / washing / drying process)
Precipitation: A solution obtained by mixing 70 parts by mass of methanol, 240 parts by mass of acetic acid and 360 parts by mass of water is added dropwise at 25 ° C. over 40 minutes with respect to 100 parts by mass of the dope. Stir for 1 hour.
Washing: Water is added to the drained precipitation cake, the temperature is raised to 80 ° C., and batch processing is performed for 60 minutes. Thereafter, washing with a large amount of water was performed for 2 hours with stirring.
Stabilization: It was immersed in an aqueous calcium hydroxide solution having a concentration of 30 ppm at room temperature for 30 minutes, and spin-dehydrated.
Drying: A comparative cellulose acetate butyrate (P-11) having an acetyl substitution degree of 0.66, a butyryl substitution degree of 2.12, and a polymerization degree of 151 was obtained by air drying at 80 ° C.

<Example 1>
<Preparation of film 1>
To 10 parts by mass of cellulose ester A, 43.9 parts by mass of dichloromethane and 3.8 parts by mass of ethanol were added and dissolved to obtain a uniform solution. Film 1 was obtained by forming this solution into a film thickness of 40 μm.

  Regarding the cellulose acylate and cellulose acylate B obtained in Comparative Synthesis Examples 1 to 9 and Synthesis Examples 1 to 11, films 2 to 20 were obtained by using the same solvent.

<Evaluation method>
-Measurement of the amount of bright spot foreign matter Two polarizing plates are placed in an orthogonal state (crossed Nicols) to block transmitted light, and the prepared sample is placed between the two polarizing plates. The polarizing plate used was a glass protective plate. Light was irradiated from one side, and the number of bright spots having a diameter of 0.01 mm or more per 100 cm ² was counted with an optical microscope (50 times) from the opposite side.
-Measurement of amount of gel-like foreign matters Gel-like foreign matters having a diameter of 0.02 mm or more per 100 cm ² were counted with an optical microscope (50 times). The gel-like foreign matters were counted after confirming that they were not bright spot foreign matters in the crossed Nicols state.

  The evaluation results are shown in Tables 1 and 2.

  From Table 1 and Table 2, it can be seen that gel foreign substances can be greatly reduced by using the method for producing a cellulose ester of the present invention.

<Example 2>
(Manufacture of acrylic resin)
[A-1 to A-3]
Acrylic resins A-1 to A-3 shown in Table 3 were produced by a known method. In Table 3, ACMO is acryloylmorpholine, VP is vinylpyrrolidone, HEMA is hydroxymethacrylate, and MMA is methylmethacrylate. In addition, the acrylic resin used is an example and is not limited to this.

(Film production)
<Optical film production>
<Melt casting method>
An optical film having the following composition was produced by a melt casting method.

  The cellulose ester A was dried under reduced pressure at 70 ° C. for 3 hours and cooled to room temperature, and then each additive was mixed. The above mixture was formed into a film by a manufacturing apparatus using an elastic touch roll. In a nitrogen atmosphere, it was melted at 240 ° C., extruded from the casting die onto the first cooling roll, and molded by pressing the film between the first cooling roll and the touch roll. Further, silica particles (manufactured by Nippon Aerosil Co., Ltd.) were added as a slip agent from the hopper opening in the middle of the extruder so as to be 0.1 part by mass.

  The heat bolt was adjusted so that the gap width of the casting die was 0.5 mm within 30 mm from the end in the width direction of the film and 1 mm at other locations. As a touch roll, 80 degreeC water was poured as cooling water in the inside.

  The circumference of the first cooling roller from the position P1 where the resin extruded from the casting die contacts the first cooling roll to the position P2 at the upstream end in the first cooling roll rotation direction of the nip between the first cooling roll and the touch roll. The length L along the surface was set to 20 mm. Thereafter, the touch roll was separated from the first cooling roll, and the temperature T of the melted part immediately before being sandwiched in the nip between the first cooling roll and the touch roll was measured. The temperature T of the melted part immediately before being squeezed by the nip between the first cooling roll and the touch roll is a thermometer (HA-200E manufactured by Anritsu Keiki Co., Ltd.) at a position 1 mm upstream from the nip upstream end P2. It was measured by. As a result of the measurement, the temperature T was 141 ° C.

  The linear pressure of the touch roll against the first cooling roll was 14.7 N / cm. Furthermore, after being introduced into a tenter and stretched 1.3 times at 160 ° C in the width direction, it was cooled to 30 ° C while relaxing 3% in the width direction, then released from the clip, the clip gripping part was cut off, and both ends of the film Was subjected to a knurling process having a width of 20 mm and a height of 25 μm, and wound on a winding core with a winding tension of 220 N / m and a taper of 40%. The film thickness was 40 μm, the winding length was 4000 m, and an optical film 1 having a refractive index of 1.49 was produced.

Cellulose ester (described in the table) 90 parts by mass Glycerin tribenzoate 10 parts by mass Tinuvin 928 (manufactured by BASF Japan) 1.1 parts by mass GSY-P101 (manufactured by Sakai Chemical Industry Co., Ltd.) 0.25 parts by mass Irganox 1010 ( BASF Japan Co., Ltd.) 0.5 parts by mass Sumilizer GS (manufactured by Sumitomo Chemical Co., Ltd.) 0.24 parts by mass R972V (manufactured by Aerosil) 0.15 parts by mass <Preparation of optical films 2-19>
All were produced by the same method as the optical film 1 except that the cellulose ester and cellulose acylate B obtained in Comparative Synthesis Examples 1 to 9 and Synthesis Examples 1 to 11 were used.

<Optical films 20 to 26>
It was produced by the same method as the optical film 1 except that a cellulose ester resin and an acrylic resin were mixed.

Acrylic resin A (described in the table) 70 parts by mass Cellulose ester (described in the table) 30 parts by mass Tinuvin 928 (manufactured by BASF Japan) 1.1 parts by mass GSY-P101 (manufactured by Sakai Chemical Industry Co., Ltd.) 0 .25 parts by mass Irganox 1010 (manufactured by BASF Japan) 0.5 parts by mass Sumilizer GS (manufactured by Sumitomo Chemical Co., Ltd.) 0.24 parts by mass R972V (manufactured by Aerosil) 0.15 parts by mass (polarizing plate)
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 at 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 polarizing film.

Subsequently, according to the following processes 1-5, the polarizing film and the cellulose-ester film were bonded together and the polarizing plate was produced.
Step 1: Optical films 1 to 26 were each immersed in a 2 mol / L sodium hydroxide solution at 50 ° C. for 90 seconds, then washed with water and dried. A protective film (made of polyethylene terephthalate) that can be removed again was attached to the surface provided with the antireflection film in advance for protection.

Similarly, a commercially available cellulose ester film was immersed in a 2 mol / L sodium hydroxide solution at 50 ° C. for 90 seconds, then washed with water and dried.
Process 2: The above-mentioned polarizing film was immersed for 1 to 2 seconds in the polyvinyl alcohol adhesive tank of 2 mass% of solid content.
Step 3: Excess adhesive adhered to the polarizing film in Step 2 was lightly removed and sandwiched between the optical film treated with alkali in Step 1 and a commercially available cellulose ester film, and laminated.
Process 4: It bonded together at the speed | rate of about 2 m / min with the pressure of 20-30 N / cm < ² > with the two rotating rollers. At this time, care was taken to prevent bubbles from entering.
Step 5: The sample prepared in Step 4 in a dryer at 80 ° C. was dried for 2 minutes to prepare a polarizing plate.

  The size of the sample at the time of evaluation of the polarizing plate is 10 cm × 10 cm for the polarizer, and 12 cm × 12 cm of the commercially available cellulose ester film used for the optical film according to the present invention sandwiching the polarizer.

(An endurance test)
Using a device called cycle thermo EC-25EXHH (Hitachi Appliance), the polarizing plate is raised from −50 ° C. to 90 ° C. every 20 ° C. every 1 hour per cycle. Humidity is changed to 20%, 50%, and 90% between 50 ° C. and 90 ° C. for each cycle. Continue to add these three cycles until 500 hours.

(Evaluation method)
(Measurement of contrast when the display panel is mounted)
For the polarizing plate obtained by the durability test, the contrast at the time of mounting the display panel was measured by evaluating the viewing angle of the display panel. Here, for viewing angle evaluation, the viewing angle of the liquid crystal display panel was measured using EZ-contrast manufactured by ELDIM. As for the measurement method, the contrast at the inclination angle of 80 ° from the normal direction to the panel surface was ranked within the range of the following values for the white display and black display contrast of the liquid crystal display panel.
◎: Contrast is omnidirectional 30 or more ◎: Contrast is omnidirectional 20 or more ○: Contrast is omnidirectional 15 or more △: Contrast is 5 or more, less than 15 area ×: Contrast is less than 5 omnidirectional Table 4 shows the above evaluation results in which regions existed.

  From the results shown in Table 4, it can be seen that excellent contrast can be obtained even after forced deterioration by using the cellulose ester produced by the production method of the present invention.

Claims (3)

A cellulose ester production method comprising a step of precipitating cellulose ester by mixing a cellulose ester solution and a poor solvent, wherein the SP value of the whole poor solvent is 30.0 to 40.0 (MPa) ^1/2 The SP value of the poor solvent is 45.0 (MPa) ^1/2 or less, and the mass of the poor solvent is 0.5 to 10.0 times the mass of the cellulose ester solution. range der of is, contains further the cellulose ester solution or alcohols at least one of the poor solvent, the mass of the alcohol is 0.5 to 10 times the weight of the cellulose ester The manufacturing method of the cellulose ester characterized by being in the inside . The SP value of the solvent in the cellulose ester solution is in the range of 18.5 to 29.0 (MPa) ^1/2 , and the SP value of the solvent after mixing the cellulose ester solution and the poor solvent is 28. It is in the range of 0-40.0 (MPa) ^1/2 , The manufacturing method of the cellulose ester of Claim 1 characterized by the above-mentioned.   The method for producing a cellulose ester according to claim 1 or 2, wherein the mass of the poor solvent is in a range of 1.0 to 5.0 times the mass of the cellulose ester solution.