JP5212043B2 - Optical film manufacturing method, optical film, polarizing plate, and display device - Google Patents

Description

  The present invention relates to an optical film manufacturing method, an optical film manufactured by the manufacturing method, and a polarizing plate and a display device using the optical film.

  A liquid crystal display device widely used as a display element includes a liquid crystal cell composed of a pair of substrates sandwiching a liquid crystal layer, a pair of polarizing plates arranged in an orthogonal state on both sides of the liquid crystal cell, and the like. Various display modes such as In-Plane Switching), TN (Twisted Nematic), and VA (Vertically Aligned) have been proposed.

  In the IPS mode, since the liquid crystal molecules rotate mainly in a plane parallel to the substrate, the difference in the degree of birefringence between when an electric field is applied and when it is not applied is small, and the viewing angle is small. It is known to spread.

  The IPS mode uses liquid crystal molecules that are homogeneously aligned in the horizontal direction and two polarizing plates that are arranged so that the transmission axis is perpendicular to the front and the left and right directions with respect to the front of the screen. When the screen is viewed obliquely from the direction, sufficient contrast can be obtained.

  On the other hand, when the screen is viewed obliquely from the direction of the azimuth angle of 45 degrees, the transmitted light is birefringent because the angle formed by the transmission axes of the two polarizing plates appears to deviate from 90 degrees. As a result of light leakage, sufficient black cannot be obtained and the contrast is lowered.

  That is, in a polarizing plate using a commonly used cellulose ester film as a protective film, there is a problem that the viewing angle becomes narrow due to the birefringence of the film, and in order to improve this, in-plane and thickness direction An optical film having a retardation value close to zero has been demanded.

  In solution casting film formation, a cellulose triacetate film with a small retardation or a specific polymer that offsets the retardation of the film is added to the cellulose ester, so that the in-plane and thickness direction retardation values are zero. A technique for obtaining a close optical film is disclosed.

  However, when this technology is applied to the melt casting method of an environmentally useful cellulose ester film in the future, since the viscosity at the time of film formation is high, the flatness of the resulting film is lower than that of the solution casting film, If the film is stored for a long time in the state of the film wound on the core, the horse's spine failure or the core portion of the film will cause a failure called core transfer and wrinkles on the film when starting to roll. It turns out that there is an easy problem.

  The horse's back failure is a failure in which the original film is deformed into a U shape like the horse's back, and a belt-like convex part is formed at a pitch of about 2 to 3 cm near the center, and the film remains deformed. This is a problem because the surface becomes distorted when processed into a polarizing plate. Until now, horse back failure has been reduced by reducing the coefficient of dynamic friction between the bases and adjusting the height of the knurling (embossing) on both sides.

  Further, the core transfer is a failure due to film deformation caused by the irregularities of the core or film. Such deformation is a problem because the surface is distorted when processed into a polarizing plate.

  An example in which a specific polymer is applied to the melt casting method is also disclosed (for example, see Patent Document 1). However, in this technique, when the draw ratio is increased, retardation is generated, so that it is difficult to perform a high-stretch process. Therefore, when processed at an unstretched or low stretch ratio, the flatness of the film is inferior, and there are cases where the horse has a back failure or a failure called core transfer, and further improvement is required for practical use. It was done.

In particular, in recent years, with the increase in size of the screen, it is desired that the width of the original film is wide and the winding length is long. For this reason, the original film becomes wide and the original film load tends to increase, and these faults are more likely to occur, and therefore improvement is desired.
JP 2007-231157 A

  Accordingly, an object of the present invention is to melt-cast and have a small retardation, a horse back failure, a failure called a core transfer in the core portion of the film, and wrinkles on the film when starting to roll. It is an object of the present invention to provide a cellulose ester-based optical film manufacturing method, an optical film, and a polarizing plate and a display device using the same, which are free from problems and are capable of producing a clear moving image without blurring or blurring.

  The above object of the present invention is achieved by the following configurations.

1. A composition comprising cellulose ester and the following polymer (I) is melt cast to form a web, and the web is stretched at least 1.1 times to 5.0 times in at least one direction. A method for producing an optical film.
Polymer (I): At least one ethylenically unsaturated monomer having a partial structure represented by the general formula (1), an aromatic group which may have a substituent, or a substituent A polymer obtained by copolymerizing at least one kind of an ethylenically unsaturated monomer containing a good heterocyclic group or an optionally substituted cycloalkyl group.

(In the formula, R ₁ , R ₂ and R ₃ each independently have an aliphatic group which may have a substituent, an aromatic group which may have a substituent, or a substituent. And any two of R ₁ , R ₂ , and R ₃ are bonded to each other, and together with the N atom to which they are bonded, or the N and C atoms An annular structure may be formed.)
2. The polymer (I) is obtained by copolymerizing an ethylenically unsaturated monomer having a partial structure represented by the general formula (1) and at least one monomer represented by the following general formula (2). 2. The method for producing an optical film as described in 1 above, which is a polymer obtained.

(Wherein R _{21 to} R ₂₈ represent a hydrogen atom or a substituent. R ₂₁ and R ₂₂ , R ₂₂ and R ₂₃ , R ₂₃ and R ₂₄ , and R ₂₄ and R ₂₅ are bonded to each other to form a ring. May be formed.)
3. The polymer (I) is obtained by copolymerizing an ethylenically unsaturated monomer having a partial structure represented by the general formula (1) and at least one monomer represented by the following general formula (3). 2. The method for producing an optical film as described in 1 above, which is a polymer obtained.

_{(Wherein, R 31} and _{R 32, .n 31} that represents a substituent, and _{n 32,} when the sum of the _{.n 31} and _{n 32} is 2 or more represents an integer of 0 to 3, more for _{R 31,} a A plurality of R ₃₂ , or R ₃₁ and R ₃₂ may be bonded to each other to form a ring.)
4). The polymer (I) is obtained by copolymerizing an ethylenically unsaturated monomer having a partial structure represented by the general formula (1) and at least one monomer represented by the following general formula (4). 2. The method for producing an optical film as described in 1 above, which is a polymer obtained.

(Wherein R _{43 to} R ₄₅ represent a hydrogen atom or a substituent. R ₄₁ represents an alkylene group. N ₄₁ represents an integer of 0 or 1. R ₄₂ has a substituent. An aromatic ring that may be substituted, a heterocyclic ring that may have a substituent, or a cycloalkyl group that may have a substituent.
5. The polymer (I) is obtained by copolymerizing an ethylenically unsaturated monomer having a partial structure represented by the general formula (1) and at least one monomer represented by the following general formula (5). 2. The method for producing an optical film as described in 1 above, which is a polymer obtained.

(In the formula, R ₅₁ and R ₅₂ represent a hydrogen atom or a substituent. X represents —NR ₅₃ — or —O—. R ₅₃ represents a hydrogen atom or a substituent.)
6). The ethylenically unsaturated monomer having a partial structure represented by the general formula (1) is N-vinylpyrrolidone, N-acryloylmorpholine, N-vinylpiperidone, N-vinylcaprolactam or a mixture thereof. The manufacturing method of the optical film of any one of said 1-5 to do.

  7). 6. The method for producing an optical film as described in any one of 1 to 5, wherein the ethylenically unsaturated monomer having a partial structure represented by the general formula (1) is N-acryloylmorpholine.

  8). 8. The method for producing an optical film as described in any one of 1 to 7, wherein the cellulose ester is a cellulose ester that simultaneously satisfies the substitution degrees of the following formulas (1) to (3).

2.40 ≦ X + Y ≦ 3.00 Formula (1)
0 ≦ X ≦ 2.40 (2)
0.10 <= Y <= 3.00 ... Formula (3)
(In the formula, X represents the substitution degree of the acetyl group. Y represents the total substitution degree of the acyl group having 3 to 5 carbon atoms.)
9. 9. An optical film produced by the method for producing an optical film according to any one of 1 to 8 above.

  10. 9. An optical film produced by the method for producing an optical film according to any one of 1 to 8, wherein an in-plane retardation (Ro) is 0 ≦ Ro ≦ 10 nm, and a thickness direction retardation (Rth). Satisfies the range of −20 ≦ Rth ≦ 20 nm at the same time.

  11. A polarizing plate characterized by using the optical film described in 9 or 10 on at least one surface.

  12 11. A display device using the optical film according to 9 or 10 or the polarizing plate according to 11 on at least one surface of a liquid crystal cell.

  13. 13. The display device as described in 12 above, wherein the liquid crystal cell is an IPS mode type.

  According to the present invention, melt casting is possible, and the retardation of the horse is low, and the core portion of the film has a failure called core transfer, and the film tends to wrinkle when starting to roll. It is possible to provide a method for producing a cellulose ester-based optical film that can produce a clear moving image free from blurring and blurring, an optical film, and a polarizing plate and a display device using the same.

  In particular, it is possible to provide an optical film that is suitably used for an IPS mode liquid crystal display device.

  The best mode for carrying out the present invention will be described in detail below, but the present invention is not limited thereto.

  The present invention provides an ethylenically unsaturated monomer having a partial structure represented by the general formula (1) and an aromatic group which may have a substituent, a heterocyclic group which may have a substituent, or By using a polymer copolymerized with an ethylenically unsaturated monomer containing an optionally substituted cycloalkyl group, melt casting is possible, and retardation is small, horse back failure and film The present inventors have found that a failure called core transfer that occurs in the core portion of the original fabric and the occurrence of wrinkles on the film at the start of winding can be improved.

  Hereinafter, the present invention will be described in detail.

(Optical film)
First, the details of the optical film of the present invention will be described.

  In the present invention, the optical film refers to a functional film used for various display devices such as a liquid crystal display, a plasma display, and an organic EL display. Specifically, a polarizing plate protective film, a retardation film, and a reflection film for a liquid crystal display device are used. An anti-reflection film, a brightness enhancement film, a hard coat film, an anti-glare film, an anti-static film, an optical compensation film for expanding the viewing angle, and the like are included.

  The optical film according to the present invention is particularly preferably used for a polarizing plate protective film, a retardation film, and an optical compensation film.

(Retardation)
The retardation of the optical film of the present invention is not particularly limited, but when used in an IPS mode type liquid crystal display device, the in-plane retardation (Ro) is 0 ≦ Ro ≦ 10 nm, and the retardation in the thickness direction. It is preferable that (Rth) satisfies the range of −20 ≦ Rth ≦ 20 nm at the same time. More preferably, (Ro) is in the range of 0 ≦ Ro ≦ 5 nm, and (Rth) is in the range of −10 ≦ Rth ≦ 10 nm, particularly preferably (Ro) is in the range of 0 ≦ Ro ≦ 5 nm, and (Rth) is in the range of −5 ≦ Rth ≦. The range is 5 nm. When an optical film having a retardation in these ranges is used, an IPS mode liquid crystal display device with less blurring and blurring and high viewing angle stability can be provided.

Retardation is a refractive index nx in the slow axis direction in the film plane, a refractive index ny in the fast axis direction, a refractive index nz in the thickness direction, and a film thickness d (nm).
Ro = (nx−ny) × d
Rth = {(nx + ny) / 2−nz} × d
Represented as:

  Retardation Ro and Rth were measured in a film sample that was allowed to stand for 24 hours in an environment of 23 ° C. and 55% RH using an automatic birefringence meter KOBRA-21ADH (manufactured by Oji Scientific Instruments). The retardation of the film at a wavelength of 590 nm was measured. It can be obtained by inputting the above-mentioned average refractive index and film thickness measured using a commercially available micrometer.

  The variation in retardation in the film plane is preferably as small as possible, usually within ± 5 nm, preferably ± 2 nm or less.

  Uniformity in the slow axis direction is also important, and the angle is preferably −5 to + 5 °, more preferably in the range of −1 to + 1 °, particularly −0. It is preferably in the range of 5 to + 0.5 °, particularly preferably in the range of −0.1 to + 0.1 °. These variations can be achieved by optimizing the stretching conditions.

(Cellulose ester)
Cellulose has a total of three hydroxyl groups, one at each of the 2nd, 3rd and 6th positions of a 1-glucose unit. The degree of substitution refers to the average number of acyl groups per 1-glucose unit. It is a numerical value that indicates how many positions are combined. Therefore, the maximum degree of substitution is 3.00, and the portion not substituted with the acyl group usually exists as a hydroxyl group. A cellulose ester in which part or all of the hydroxyl group of cellulose is substituted with an acyl group is called a cellulose ester. In addition, the substitution degree of an acyl group can be calculated | required by the method prescribed | regulated to ASTM-D817.

  In the cellulose ester used in the melt casting method of the present invention, X is the sum of the average degree of substitution by acetyl groups at the 2nd, 3rd, and 6th positions, and the number of carbon atoms at the 2nd, 3rd, and 6th positions is 3-5. A cellulose ester that simultaneously satisfies the following formulas (1) to (3) is preferred when the total average degree of substitution of the acyl groups is Y (hereinafter, the average degree of substitution is simply referred to as the degree of substitution).

2.40 ≦ X + Y ≦ 3.00 Formula (1)
0 ≦ X ≦ 2.40 (2)
0.10 ≦ Y <3.00 Formula (3)
(In the formula, X represents the substitution degree of the acetyl group. Y represents the total substitution degree of the acyl group having 3 to 5 carbon atoms.)
Of these, cellulose acetate propionate is particularly preferably used, and among them, 1.00 ≦ A ≦ 2.20 and 0.50 ≦ B ≦ 2.00 are preferable. More preferably, 1.20 ≦ A ≦ 2.00 and 0.70 ≦ B ≦ 1.70.

  Next, a method for synthesizing the cellulose ester used in the present invention will be described.

  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, but softwood is more preferred. A cotton linter is preferably used from the viewpoint of peelability during film formation. 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.

  The cellulose ester of the present invention can be synthesized with reference to known methods. For example, it can be obtained by substituting the acetyl group, the propionyl group, or the butyryl group within the above-mentioned range by a conventional method using acetic anhydride and propionic anhydride and / or butyric anhydride for the hydroxyl group of the raw material cellulose. The cellulose ester of this invention which satisfy | fills said Formula (1)-(3) simultaneously can be synthesize | combined using the above methods. The method for synthesizing such a cellulose ester is not particularly limited, and for example, it can be synthesized with reference to the method described in JP-A-10-45804 or JP-A-6-501040.

  The cellulose ester of the present invention is not particularly limited, but preferably has a weight average molecular weight (Mw) of 150,000 to 250,000, more preferably has a weight average molecular weight of 180,000 to 230,000, and 190,000 to Most preferably, it has a weight average molecular weight of 220,000.

  When the weight average molecular weight is within the above-mentioned preferable range, it is preferable because the melt viscosity is not too high and the strength of the resulting film is not lowered. Further, the cellulose ester used in the present invention preferably has a weight average molecular weight (Mw) / number average molecular weight (Mn) ratio of 1.3 to 5.5, particularly preferably 1.5 to 5.0. More preferably, it is 1.7-4.0, More preferably, the cellulose ester of 2.0-3.5 is used preferably. When Mw / Mn exceeds 5.5, the viscosity increases, and melt filterability tends to decrease, such being undesirable. On the other hand, from the viewpoint of industrial production characteristics, it is preferably 1.3 or more.

  Mw and Mw / Mn can be calculated by gel permeation chromatography (GPC) in the following manner.

  The measurement conditions are as follows.

Solvent: Tetrahydrofuran Device: HLC-8220 (manufactured by Tosoh Corporation)
Column: TSKgel SuperHM-M (manufactured by Tosoh Corporation)
Column temperature: 40 ° C
Sample concentration: 0.1% by mass
Injection volume: 10 μl
Flow rate: 0.6ml / min
Calibration curve: Standard polystyrene: PS-1 (manufactured by Polymer Laboratories) Mw = 2, 560,000 to 580, a calibration curve with 9 samples was used.

  The alkaline earth metal content of the cellulose ester of the present invention is preferably in the range of 1 to 50 ppm.

  When the range of the alkaline earth metal content of the cellulose ester is 1 to 50 ppm, there is no increase in lip adhesion stains, and there is no breakage in the slitting part at the time of hot drawing or after hot drawing, and the effect of the present invention is further improved. It is preferable in terms of performance. Furthermore, in this invention, the range whose alkaline-earth metal content of a rosester is 1-30 ppm is preferable. The alkaline earth metal as used herein refers to the total content of Ca and Mg, and can be measured using an X-ray photoelectron spectrometer (XPS).

  The residual sulfuric acid content in the cellulose ester of the present invention is preferably in the range of 0.1 to 45 ppm in terms of elemental sulfur. These are considered to be contained in the form of salts. When the residual sulfuric acid content exceeds 45 ppm, there is a tendency that deposits on the die lip portion during heat melting increase. In addition, there is a tendency to break easily during slitting at the time of hot drawing or after hot drawing. Therefore, the range of 1-30 ppm is more preferable. The residual sulfuric acid content can be measured by the method prescribed in ASTM D817-96.

  The free acid content in the cellulose ester of the present invention is preferably 1 to 500 ppm. Within the above range, the deposit on the die lip does not increase and is difficult to break. Furthermore, about this invention, it is preferable that it is the range of 1-100 ppm, and also it becomes difficult to fracture | rupture. A range of 1 to 70 ppm is particularly preferable. The free acid content can be measured by the method prescribed in ASTM D817-96.

  By washing the synthesized cellulose ester more sufficiently than when used in the solution casting method, the residual alkaline earth metal content, residual sulfuric acid content, and residual acid content are within the above ranges. This is preferable.

  In addition to washing with water, cellulose ester can be washed with a poor solvent such as methanol or ethanol, or as a result, a mixed solvent of a poor solvent and a good solvent can be used as a poor solvent. Low molecular organic impurities can be removed.

  Further, the washing of the cellulose ester is also preferably performed in the presence of a deterioration inhibitor, and the heat resistance and film forming stability of the cellulose ester are improved.

  The deterioration preventing agent used is not limited as long as it is a compound that inactivates radicals generated in the cellulose ester or suppresses deterioration of the cellulose ester caused by addition of oxygen to the radical generated in the cellulose ester. However, hindered phenol compounds, hindered amine compounds, and phosphorus compounds are preferred.

  In order to improve the heat resistance, mechanical properties, optical properties, etc. of cellulose ester, dissolve it in a good solvent of cellulose ester, reprecipitate it in a poor solvent, filter it, or stir and suspend it in the poor solvent. The low molecular weight component of cellulose ester and other impurities can be removed by filtration. At this time, it is preferable to carry out in the presence of a deterioration preventing agent, similarly to the above-described washing of the cellulose ester. The deterioration inhibitor used for washing the cellulose ester may remain in the cellulose ester after washing. The remaining amount is preferably 0.01 to 2000 ppm, more preferably 0.05 to 1000 ppm. More preferably, it is 0.1-100 ppm. Furthermore, another polymer or a low molecular weight compound may be added after the cellulose ester reprecipitation treatment. In the optical film of the present invention, the cellulose ester contained in the cellulose ester film is preferably 60 to 99% by mass.

  Moreover, it is preferable that the cellulose ester of this invention has few bright spot foreign materials when it is made into a film. A bright spot foreign material is an arrangement in which two polarizing plates are arranged orthogonally (crossed Nicols), a cellulose ester film is arranged between them, light from the light source is applied from one side, and the cellulose ester film is applied from the other side. This is the point where the light from the light source appears to leak when observed. At this time, the polarizing plate used for the evaluation is desirably composed of a protective film having no bright spot foreign matter, and a polarizing plate using a glass plate for protecting the polarizer is preferably used. The bright spot foreign matter is considered to be one of the causes of unacylated or low acyl cellulose contained in the cellulose ester, and use a cellulose ester with a little bright spot foreign matter (use a cellulose ester with a small dispersion of substitution degree). In addition, at least one of the process of filtering the melted cellulose ester and the process of obtaining the cellulose ester later and the step of obtaining the precipitate, the bright spot foreign matter may be removed through the filtration process in the same manner once in the solution state. it can.

As the film thickness decreases, the number of bright spot foreign matter per unit area decreases, and as the cellulose ester content in the film decreases, the bright spot foreign matter tends to decrease. 0.01 mm or more is preferably 200 pieces / cm ² or less, more preferably 100 pieces / cm ² or less, further preferably 50 pieces / cm ² or less, and 30 pieces / cm ² or less. The number is preferably 10 pieces / cm ² or less, but most preferably none. Moreover, it is preferable that it is 200 pieces / cm < ² > or less also about the bright spot of 0.005-0.01 mm or less, Furthermore, it is preferable that it is 100 pieces / cm < ² > or less, It is 50 pieces / cm < ² > or less. The number is preferably 30 pieces / cm ² or less, more preferably 10 pieces / cm ² or less, and most preferably none.

  When removing bright spot foreign matter by melt filtration, it is more effective to remove the bright spot foreign matter by filtering a composition in which a plasticizer, an anti-degradation agent, etc. are added and mixed than by filtering a melted cellulose ester alone. Highly preferred. Of course, the cellulose ester may be dissolved in a solvent during the synthesis and reduced by filtration. What mixed the ultraviolet absorber and other additives suitably can be filtered. In the melt filtration, the melt containing cellulose ester is preferably filtered with a viscosity of 10,000 Pa · s or less, more preferably 5000 Pa · s or less, further preferably 1000 Pa · s or less, and more preferably 500 Pa · s or less. More preferably it is. As the filter medium, conventionally known materials such as glass fibers, cellulose fibers, filter paper, and fluorine resins such as tetrafluoroethylene resin are preferably used, and ceramics and metals are particularly preferably used. The absolute filtration accuracy is preferably 50 μm or less, more preferably 30 μm or less, still more preferably 10 μm or less, and even more preferably 5 μm or less. These can be used in combination as appropriate. The filter medium can be either a surface type or a depth type, but the depth type is preferably used because it is relatively less clogged.

  In another embodiment, the cellulose ester as a raw material may be dissolved at least once in a solvent, or a cellulose ester obtained by suspending and washing in a solvent and then drying the solvent may be used. In that case, you may make it melt | dissolve in a solvent with at least 1 or more of a plasticizer, a ultraviolet absorber, a deterioration inhibitor, antioxidant, and a mat agent. As the solvent, a good solvent used in a solution casting method such as methylene chloride, methyl acetate or dioxolane may be used, or a poor solvent such as methanol, ethanol or butanol may be used, or a mixed solvent thereof may be used. . In the process of dissolution, it may be cooled to -20 ° C or lower, or heated to 80 ° C or higher. When such a cellulose ester is used, each additive in a molten state can be easily made uniform, and optical characteristics can be made uniform.

(Polymer (I))
First, the ethylenically unsaturated monomer having the partial structure represented by the general formula (1) will be described.

In the general formula (1), R ₁ , R ₂ , and R ₃ are each independently an aliphatic group that may have a substituent, an aromatic group that may have a substituent, Or it represents the heterocyclic group which may have a substituent. Further, any two of R ₁ , R ₂ , and R ₃ may be bonded to each other to form a cyclic structure together with the N atom to which they are bonded, or the N atom and the C atom.

An aliphatic group which may have a substituent represented by R ₁ , R ₂ and R ₃ , an aromatic group which may have a substituent, and a heterocycle which may have a substituent The ring group is not particularly limited. For example, an alkyl group (for example, methyl group, ethyl group, propyl group, isopropyl group, t-butyl group, pentyl group, hexyl group, octyl group, dodecyl group, trifluoromethyl group) Group), cycloalkyl group (eg, cyclopentyl group, cyclohexyl group, etc.), aryl group (eg, phenyl group, naphthyl group, etc.), acylamino group (eg, acetylamino group, benzoylamino group, etc.), alkylthio group (eg, , Methylthio group, ethylthio group, etc.), arylthio group (for example, phenylthio group, naphthylthio group, etc.), alkenyl group (for example, vinyl group, 2-propyl group, etc.) Nyl group, 3-butenyl group, 1-methyl-3-propenyl group, 3-pentenyl group, 1-methyl-3-butenyl group, 4-hexenyl group, cyclohexenyl group, etc.), halogen atom (for example, fluorine atom, Chlorine atom, bromine atom, iodine atom, etc.), alkynyl group (eg, propargyl group, etc.), heterocyclic group (eg, pyridyl group, thiazolyl group, oxazolyl group, imidazolyl group, etc.), alkylsulfonyl group (eg, methylsulfonyl group) , Ethylsulfonyl group etc.), arylsulfonyl group (eg phenylsulfonyl group, naphthylsulfonyl group etc.), alkylsulfinyl group (eg methylsulfinyl group etc.), arylsulfinyl group (eg phenylsulfinyl group etc.), phosphono group, Acyl groups (eg acetyl, pivaloyl, benzoy Carbamoyl group (for example, aminocarbonyl group, methylaminocarbonyl group, dimethylaminocarbonyl group, butylaminocarbonyl group, cyclohexylaminocarbonyl group, phenylaminocarbonyl group, 2-pyridylaminocarbonyl group, etc.), sulfamoyl group ( For example, aminosulfonyl group, methylaminosulfonyl group, dimethylaminosulfonyl group, butylaminosulfonyl group, hexylaminosulfonyl group, cyclohexylaminosulfonyl group, octylaminosulfonyl group, dodecylaminosulfonyl group, phenylaminosulfonyl group, naphthylaminosulfonyl group , 2-pyridylaminosulfonyl group, etc.), sulfonamide group (eg, methanesulfonamide group, benzenesulfonamide group, etc.), cyano group, alkoxy Group (for example, methoxy group, ethoxy group, propoxy group, etc.), aryloxy group (for example, phenoxy group, naphthyloxy group, etc.), heterocyclic oxy group, siloxy group, acyloxy group (for example, acetyloxy group, benzoyloxy group) Etc.), sulfonic acid group, sulfonic acid salt, aminocarbonyloxy group, amino group (for example, amino group, ethylamino group, dimethylamino group, butylamino group, cyclopentylamino group, 2-ethylhexylamino group, dodecylamino group) Etc.), anilino group (for example, phenylamino group, chlorophenylamino group, toluidino group, anisidino group, naphthylamino group, 2-pyridylamino group, etc.), imide group, ureido group (for example, methylureido group, ethylureido group, pentyl) Ureido group, cyclohexylureido group, Cutylureido group, dodecylureido group, phenylureido group, naphthylureido group, 2-pyridylaminoureido group, etc.), alkoxycarbonylamino group (eg methoxycarbonylamino group, phenoxycarbonylamino group etc.), alkoxycarbonyl group (eg methoxycarbonyl) Group, ethoxycarbonyl group, phenoxycarbonyl, etc.), aryloxycarbonyl group (eg, phenoxycarbonyl group, etc.), heterocyclic thio group, thioureido group, carboxyl group, carboxylic acid salt, hydroxyl group, mercapto group, nitro group, etc. Each group is mentioned. These substituents may be further substituted with the same substituent.

  Examples of the aliphatic group which may have a substituent include an alkyl group (for example, methyl group, ethyl group, propyl group, isopropyl group, t-butyl group, pentyl group, hexyl group, octyl group, dodecyl group, trimethyl group). Fluoromethyl group, etc.).

  As an aromatic group which may have a substituent, an aryl group (for example, a phenyl group, a naphthyl group, etc.) is mentioned.

Examples of the heterocyclic group which may have a substituent include a cycloalkyl group (for example, a cyclopentyl group, a cyclohexyl group, etc.),
Heterocyclic groups (for example, pyridyl group, thiazolyl group, oxazolyl group, imidazolyl group, etc.) can be mentioned.

  Preferably, they are a methyl group, an ethyl group, a phenyl group, and a cyclohexyl group.

As a ring in the case where any two of R ₁ , R ₂ , and R ₃ are bonded to each other and they are bonded to each other, or together with the N and C atoms, form a cyclic structure Includes a saturated or unsaturated monocyclic, polycyclic or condensed ring which may further have a nitrogen atom, a sulfur atom or an oxygen atom in the ring. Specific examples thereof include, for example, pyridine. Examples thereof include heterocyclic rings such as a ring, thiazole ring, piperidine ring, piperazine ring, pyrrole ring, morpholine ring, imidazole ring, indole ring, quinoline ring, pyrimidine ring, and isoindoline ring.

  Moreover, although it has an ethylenically unsaturated bond in the molecule, specific examples include, for example, vinyl group, allyl group, acryloyl group, methacryloyl group, styryl group, acrylamide group, methacrylamide group, vinyl cyanide group, 2- A cyanoacryloxy group, a 1,2-epoxy group, a vinylbenzyl group, a vinyl ether group, and the like can be mentioned, and a vinyl group, an acryloyl group, a methacryloyl group, an acrylamide group, and a methacrylamide group are preferable.

The substituent that the aliphatic group, aromatic group, or heterocyclic group represented by R ₁ , R ₂ , and R ₃ may have is not particularly limited, and examples thereof include an alkyl group (for example, a methyl group, Ethyl group, propyl group, isopropyl group, t-butyl group, pentyl group, hexyl group, octyl group, dodecyl group, trifluoromethyl group, etc.), cycloalkyl group (eg, cyclopentyl group, cyclohexyl group etc.), aryl group ( For example, phenyl group, naphthyl group, etc.), acylamino group (eg, acetylamino group, benzoylamino group, etc.), alkylthio group (eg, methylthio group, ethylthio group, etc.), arylthio group (eg, phenylthio group, naphthylthio group, etc.) Alkenyl group (for example, vinyl group, 2-propenyl group, 3-butenyl group, 1-methyl-3-propenyl group) 3-pentenyl group, 1-methyl-3-butenyl group, 4-hexenyl group, cyclohexenyl group, etc.), halogen atom (eg, fluorine atom, chlorine atom, bromine atom, iodine atom etc.), alkynyl group (eg, propargyl) Group), heterocyclic group (for example, pyridyl group, thiazolyl group, oxazolyl group, imidazolyl group, etc.), alkylsulfonyl group (for example, methylsulfonyl group, ethylsulfonyl group, etc.), arylsulfonyl group (for example, phenylsulfonyl group, Naphthylsulfonyl group etc.), alkylsulfinyl group (eg methylsulfinyl group etc.), arylsulfinyl group (eg phenylsulfinyl group etc.), phosphono group, acyl group (eg acetyl group, pivaloyl group, benzoyl group etc.), carbamoyl A group (for example, an aminocarbonyl group, Methylaminocarbonyl group, dimethylaminocarbonyl group, butylaminocarbonyl group, cyclohexylaminocarbonyl group, phenylaminocarbonyl group, 2-pyridylaminocarbonyl group, etc.), sulfamoyl group (for example, aminosulfonyl group, methylaminosulfonyl group, dimethylaminosulfonyl) Group, butylaminosulfonyl group, hexylaminosulfonyl group, cyclohexylaminosulfonyl group, octylaminosulfonyl group, dodecylaminosulfonyl group, phenylaminosulfonyl group, naphthylaminosulfonyl group, 2-pyridylaminosulfonyl group, etc.), sulfonamide group (for example, Methanesulfonamide group, benzenesulfonamide group, etc.), cyano group, alkoxy group (for example, methoxy group, ethoxy group, propoxy group, etc.) Aryloxy groups (eg, phenoxy group, naphthyloxy group, etc.), heterocyclic oxy groups, siloxy groups, acyloxy groups (eg, acetyloxy group, benzoyloxy group, etc.), sulfonic acid groups, sulfonic acid salts, aminocarbonyloxy Group, amino group (for example, amino group, ethylamino group, dimethylamino group, butylamino group, cyclopentylamino group, 2-ethylhexylamino group, dodecylamino group), anilino group (for example, phenylamino group, chlorophenylamino group) , Toluidino group, anisidino group, naphthylamino group, 2-pyridylamino group, etc., imide group, ureido group (for example, methylureido group, ethylureido group, pentylureido group, cyclohexylureido group, octylureido group, dodecylureido group, Phenylurei Group, naphthylureido group, 2-pyridylaminoureido group, etc.), alkoxycarbonylamino group (eg, methoxycarbonylamino group, phenoxycarbonylamino group, etc.), alkoxycarbonyl group (eg, methoxycarbonyl group, ethoxycarbonyl group, phenoxycarbonyl, etc.) ), Aryloxycarbonyl groups (for example, phenoxycarbonyl group, etc.), heterocyclic thio groups, thioureido groups, carboxyl groups, carboxylic acid salts, hydroxyl groups, mercapto groups, nitro groups, and the like. These substituents may be further substituted with the same substituent.

  Although the preferable specific example of the ethylenically unsaturated monomer which has the partial structure represented by the said General formula (1) in the said molecule | numerator used by this invention below is illustrated, it is not limited to these.

  The ethylenically unsaturated monomer having a partial structure represented by the general formula (1) in the molecule can be used alone or in combination of two or more, and particularly preferably N-vinylpyrrolidone, N-acryloylmorpholine, N-vinyl piperidone, N-vinyl caprolactam or a mixture thereof.

  The ethylenically unsaturated monomer having a partial structure represented by the general formula (1) in the molecule used in the present invention can be obtained as a commercial product or synthesized with reference to known literature.

  Next, the aromatic group which may have a substituent copolymerized with the ethylenically unsaturated monomer which has the partial structure represented by the said General formula (1), and the heterocyclic ring which may have a substituent An ethylenically unsaturated monomer containing a cycloalkyl group which may have a group or a substituent will be described.

  First, the monomer represented by the general formula (2) will be described.

_Wherein, R 21 _{to R 28} each independently represent a hydrogen atom or a substituent.

  Examples of the substituent include an alkyl group (for example, methyl group, ethyl group, propyl group, isopropyl group, t-butyl group, pentyl group, hexyl group, octyl group, dodecyl group, trifluoromethyl group, etc.), cycloalkyl group ( For example, cyclopentyl group, cyclohexyl group, etc.), aryl group (eg, phenyl group, naphthyl group, etc.), acylamino group (eg, acetylamino group, benzoylamino group, etc.), alkylthio group (eg, methylthio group, ethylthio group, etc.) , Arylthio groups (for example, phenylthio group, naphthylthio group, etc.), alkenyl groups (for example, vinyl group, 2-propenyl group, 3-butenyl group, 1-methyl-3-propenyl group, 3-pentenyl group, 1-methyl- 3-butenyl group, 4-hexenyl group, cyclohexenyl group, etc.), halogen atom ( For example, fluorine atom, chlorine atom, bromine atom, iodine atom etc.), alkynyl group (eg propargyl group etc.), heterocyclic group (eg pyridyl group, thiazolyl group, oxazolyl group, imidazolyl group etc.), alkylsulfonyl group (eg For example, methylsulfonyl group, ethylsulfonyl group, etc.), arylsulfonyl group (eg, phenylsulfonyl group, naphthylsulfonyl group, etc.), alkylsulfinyl group (eg, methylsulfinyl group, etc.), arylsulfinyl group (eg, phenylsulfinyl group, etc.) ), Phosphono group, acyl group (for example, acetyl group, pivaloyl group, benzoyl group, etc.), carbamoyl group (for example, aminocarbonyl group, methylaminocarbonyl group, dimethylaminocarbonyl group, butylaminocarbonyl group, cyclohexylamino group). Bonyl group, phenylaminocarbonyl group, 2-pyridylaminocarbonyl group, etc.), sulfamoyl group (for example, aminosulfonyl group, methylaminosulfonyl group, dimethylaminosulfonyl group, butylaminosulfonyl group, hexylaminosulfonyl group, cyclohexylaminosulfonyl group, Octylaminosulfonyl group, dodecylaminosulfonyl group, phenylaminosulfonyl group, naphthylaminosulfonyl group, 2-pyridylaminosulfonyl group, etc.), sulfonamide group (for example, methanesulfonamide group, benzenesulfonamide group, etc.), cyano group, alkoxy Group (for example, methoxy group, ethoxy group, propoxy group, etc.), aryloxy group (for example, phenoxy group, naphthyloxy group, etc.), heterocyclic oxy group, siloxy group, acyloxy Group (for example, acetyloxy group, benzoyloxy group, etc.), sulfonic acid group, salt of sulfonic acid, aminocarbonyloxy group, amino group (for example, amino group, ethylamino group, dimethylamino group, butylamino group, cyclopentylamino) Group, 2-ethylhexylamino group, dodecylamino group, etc.), anilino group (for example, phenylamino group, chlorophenylamino group, toluidino group, anisidino group, naphthylamino group, 2-pyridylamino group, etc.), imide group, ureido group ( For example, methylureido group, ethylureido group, pentylureido group, cyclohexylureido group, octylureido group, dodecylureido group, phenylureido group, naphthylureido group, 2-pyridylaminoureido group, etc.), alkoxycarbonylamino group (for example, methoxy group) Carbonylamino group, phenoxycarbonylamino group, etc.), alkoxycarbonyl group (eg, methoxycarbonyl group, ethoxycarbonyl group, phenoxycarbonyl, etc.), aryloxycarbonyl group (eg, phenoxycarbonyl group, etc.), heterocyclic thio group, thioureido group , Carboxyl groups, carboxylic acid salts, hydroxyl groups, mercapto groups, nitro groups and the like. These substituents may be further substituted with the same substituent.

R ₂₁ and R ₂₂ , R ₂₂ and R ₂₃ , R ₂₃ and R ₂₄ , and R ₂₄ and R ₂₅ may be bonded to each other to form a ring.

R _{21 to} R ₂₈ are preferably a hydrogen atom, an alkyl group (for example, methyl group, ethyl group, propyl group, isopropyl group, t-butyl group, pentyl group, hexyl group, octyl group, dodecyl group, trifluoromethyl group). Etc.), acyloxy group (eg acetyloxy group, benzoyloxy group etc.), alkoxy group (eg methoxy group, ethoxy group, propoxy group etc.), aryloxy group (eg phenoxy group, naphthyloxy group etc.), hydroxyl Groups are preferred.

  In particular, a hydrogen atom and an alkyl group are preferable.

  Although the preferable specific example of the monomer represented by the said General formula (2) used by this invention below is illustrated, it is not limited to these.

  The monomer represented by the general formula (3) will be described.

In the formula, R ₃₁ and R ₃₂ represent a substituent.

  Examples of the substituent include the substituents exemplified in the general formula (2).

R ₃₁ and R ₃₂ are preferably a hydrogen atom, an alkyl group (for example, methyl group, ethyl group, propyl group, isopropyl group, t-butyl group, pentyl group, hexyl group, octyl group, dodecyl group, trifluoromethyl group). Etc.), acyloxy groups (for example, acetyloxy group, benzoyloxy group, etc.), and alkoxy groups (for example, methoxy group, ethoxy group, propoxy group, etc.) are preferable.

  Particularly preferred is a hydrogen atom.

n ₃₁ and _{n 32} represents an integer of 0 to 3. When the total of n ₃₁ and n ₃₂ is 2 or more, a plurality of R ₃₁ , a plurality of R ₃₂ , or R ₃₁ and R ₃₂ may be bonded to each other to form a ring.

n ₃₁ and n ₃₂ are preferably 0.

  Although the preferable specific example of the monomer represented by the said General formula (3) used by this invention below is illustrated, it is not limited to these.

  The monomer represented by the general formula (4) will be described.

_Wherein, R 43 _{to R 45} represents a hydrogen atom or a substituent.

  Examples of the substituent include the substituents exemplified in the general formula (2).

R _{43 to} R ₄₅ are preferably a hydrogen atom, an alkyl group (for example, methyl group, ethyl group, propyl group, isopropyl group, t-butyl group, pentyl group, hexyl group, octyl group, dodecyl group, trifluoromethyl group). Etc.).

R ₄₁ represents an alkylene group (for example, a methylene group, an ethylene group, a propylene group, etc.). n ₄₁ represents an integer of 0 or 1.

R ₄₂ represents an aromatic ring (eg, phenyl group, naphthyl group, etc.) which may have a substituent, or a heterocyclic ring (eg, tetrahydrofuran group, pyridyl group, thiazolyl group, oxazolyl) which may have a substituent. Group, an imidazolyl group, or the like), or an optionally substituted cycloalkyl group (for example, a cyclopentyl group, a cyclohexyl group, or the like).

Preferably n ₄₁ is 0.

  Although the preferable specific example of a monomer represented by General formula (4) used by this invention below is illustrated, it is not limited to these.

  The monomer represented by the general formula (5) will be described.

In the formula, R ₅₁ and R ₅₂ represent a hydrogen atom or a substituent.

  Examples of the substituent include the substituents exemplified in the general formula (2).

R ₅₁ and R ₅₂ are preferably a hydrogen atom or an alkyl group (for example, methyl group, ethyl group, propyl group, isopropyl group, t-butyl group, pentyl group, hexyl group, octyl group, dodecyl group, trifluoromethyl group). Etc.).

X represents —NR ₅₃ — or —O—. R ₅₃ represents a hydrogen atom or a substituent.

  Examples of the substituent include the substituents exemplified in the general formula (2).

R ₅₃ is preferably an aryl group which may have a substituent (for example, phenyl group, naphthyl group, etc.).

  Although the preferable specific example of the monomer represented by General formula (5) used by this invention below is illustrated, it is not limited to these.

  The monomers having the partial structures represented by the general formulas (2) to (5) can be used alone or in combination of two or more.

  The polymer represented by (I) of the present invention may be a copolymer with another polymerizable monomer. Examples of the other polymerizable monomer that can be copolymerized include an acrylate derivative (for example, acrylic acid). Methyl, ethyl acrylate, propyl acrylate, butyl acrylate, i-butyl acrylate, t-butyl acrylate, octyl acrylate, etc.), methacrylate derivatives (eg, methyl methacrylate, ethyl methacrylate, propyl methacrylate) , Butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, octyl methacrylate, etc.), alkyl vinyl ethers (eg, methyl vinyl ether, ethyl vinyl ether, butyl vinyl ether), alkyl vinyl esters (eg, vinyl formate, vinyl acetate) , Vinyl butyrate , Vinyl caproate, vinyl stearate, etc.), crotonic acid, maleic acid, fumaric acid, itaconic acid, acrylonitrile, methacrylonitrile, vinyl chloride, vinylidene chloride, acrylamide, methacrylamide, hydroxyl group or carboxyl group in the molecule ( Examples thereof include unsaturated compounds such as (meth) acrylate (for example, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, and the like). Preferred are methyl acrylate, methyl methacrylate, and vinyl acetate.

  The weight average molecular weight of the polymer represented by (I) of the present invention is preferably 1000 or more and 30000 or less, more preferably 2000 or more and 20000 or less. Furthermore, 5000 or more and 10,000 or less are more preferable.

  When the weight average molecular weight is less than 1000, exudation to the film surface tends to occur, and when it is more than 30000, compatibility with the resin tends to deteriorate.

  Furthermore, it is preferable that the amount of the low molecular weight component in the polymer represented by (I) of the present invention is small, the ratio of the low molecular weight component having a molecular weight of less than 1000 is preferably 5% by mass or less, and more preferably 1% by mass or less. It is. The polymer represented by the general formula (I) of the present invention preferably has a weight average molecular weight Mw / number average molecular weight Mn ratio of 1.5 to 4.0, particularly preferably 1.5 to 3.0. It is.

  The measuring method of a weight average molecular weight can be calculated | required by the following method.

(Average molecular weight measurement method)
The weight average molecular weight Mw and the number average molecular weight Mn were measured using gel permeation chromatography (GPC).

  The measurement conditions are as follows.

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

  The method for polymerizing the polymer represented by (I) of the present invention is not particularly limited, but conventionally known methods can be widely employed, and examples thereof include radical polymerization, anionic polymerization, and cationic polymerization. Examples of the initiator for the radical polymerization method include azo compounds and peroxides, and examples thereof include azobisisobutyronitrile (AIBN), azobisisobutyric acid diester derivatives, and benzoyl peroxide. The polymerization solvent is not particularly limited. For example, aromatic hydrocarbon solvents such as toluene and chlorobenzene, halogenated hydrocarbon solvents such as dichloroethane and chloroform, ether solvents such as tetrahydrofuran and dioxane, and amide solvents such as dimethylformamide. And alcohol solvents such as methanol, ester solvents such as methyl acetate and ethyl acetate, ketone solvents such as acetone, cyclohexanone and methyl ethyl ketone, and water solvents. Depending on the selection of the solvent, solution polymerization for polymerization in a homogeneous system, precipitation polymerization for precipitation of the produced polymer, and emulsion polymerization for polymerization in a micellar state can also be performed.

  In the present invention, the weight average molecular weight of the polymer represented by (I) can be adjusted by a known molecular weight adjusting method. Examples of such a molecular weight adjusting method include a method of adding a chain transfer agent such as carbon tetrachloride, lauryl mercaptan, octyl thioglycolate, and the like. The polymerization temperature is usually from room temperature to 130 ° C, preferably from 50 ° C to 110 ° C.

  The proportion of each monomer used is appropriately selected in consideration of the compatibility between the obtained polymer represented by the general formula (I) and other transparent polymers and the effects on the transparency and mechanical strength of the optical film.

  The content ratio of the ethylenically unsaturated monomer having the partial structure represented by the general formula (1) in the polymer molecule represented by (I) of the present invention is preferably 10 to 90% by mass. More preferably, it is 30-70 mass%. The content ratio of the monomers represented by the general formulas (2) to (5) in the polymer represented by (I) of the present invention is preferably 1 to 90% by mass, more preferably 10%. -70 mass%.

  The addition amount of the polymer represented by the general formula (I) is 0.1 to 50 parts by mass, preferably 1 to 30 parts by mass, more preferably 3 to 15 parts by mass with respect to 100 parts by mass of the cellulose ester. .

  Although the preferable specific example of the polymer represented by general formula (I) used by this invention below is illustrated, it is not limited to these.

(Other additives)
The optical film of the present invention preferably contains, in addition to the cellulose ester and the polymer (I), other additives such as a plasticizer, an antioxidant, an ultraviolet absorber, and particles (matting agent).

(Plasticizer)
It is preferable to add a plasticizer to the optical film of the present invention. In general, it is preferable to add a compound known as a plasticizer from the viewpoint of film modification such as improvement of mechanical properties, imparting flexibility, imparting water absorption resistance, and reducing moisture permeability. In addition, in the melt casting method, the film contains a plasticizer rather than the cellulose ester at the same heating temperature for the purpose of lowering the melting temperature of the film constituent material by adding a plasticizer rather than the glass transition temperature of the cellulose ester used alone. It includes the purpose of reducing the viscosity of the constituent materials. Here, in the present invention, the melting temperature of the film constituent material means a temperature at which the material is heated in a state where the material is heated and fluidity is developed.

  If the cellulose ester alone is lower than the glass transition temperature, the fluidity for forming a film is not exhibited. However, the cellulose ester exhibits a fluidity due to a decrease in elastic modulus or viscosity due to heat absorption above the glass transition temperature. In order to melt the film constituent material, the plasticizer to be added preferably has a melting point or glass transition temperature lower than the glass transition temperature of the cellulose ester in order to satisfy the above-mentioned purpose. Furthermore, an ester plasticizer composed of a polyhydric alcohol and a monovalent carboxylic acid, and an ester plasticizer composed of a polyvalent carboxylic acid and a monovalent alcohol have a high affinity with the cellulose ester, and are more preferable. Examples of the polyhydric alcohol that is a raw material of the ester plasticizer preferably used in the present invention include the following, but the present invention is not limited thereto. Adonitol, arabitol, ethylene glycol, glycerin, diglycerin, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propanediol, dipropylene glycol, tripropylene glycol, 1,2-butanediol 1,3-butanediol, 1,4-butanediol, dibutylene glycol, 1,2,4-butanetriol, 1,5-pentanediol, 1,6-hexanediol, hexanetriol, galactitol, mannitol, 3-methylpentane-1,3,5-triol, pinacol, sorbitol, trimethylolpropane, ditrimethylolpropane, trimethylolethane, pentaethysitol, dipentaerythritol, xylene Mention may be made of the toll and the like. In particular, ethylene glycol, glycerin, and trimethylolpropane are preferable.

  Specific examples of ethylene glycol ester plasticizers that are one of the polyhydric alcohol esters include ethylene glycol alkyl ester plasticizers such as ethylene glycol diacetate and ethylene glycol dibutyrate, and ethylene glycol dicyclopropyl. Examples thereof include ethylene glycol cycloalkyl ester plasticizers such as carboxylate and ethylene glycol dicyclohexylcarboxylate, and ethylene glycol aryl ester plasticizers such as ethylene glycol dibenzoate and ethylene glycol di4-methylbenzoate. These alkylate groups, cycloalkylate groups, and arylate groups may be the same or different, and may be further substituted. Moreover, the mix of an alkylate group, a cycloalkylate group, and an arylate group may be sufficient, and these substituents may couple | bond together by the covalent bond. Further, the ethylene glycol part may be substituted, and the ethylene glycol ester partial structure may be part of the polymer or regularly pendant, and may be an antioxidant, an acid scavenger, an ultraviolet absorber, etc. It may be introduced into a part of the molecular structure of the additive.

  Specific examples of the glycerin ester plasticizer that is one of the polyhydric alcohol esters include glycerol alkyl esters such as triacetin, tributyrin, glycerol diacetate caprylate, glycerol oleate propionate, and glycerol tricyclopropylcarboxylate. Glycerol glycerol esters such as glycerol tricyclohexyl carboxylate, glycerol aryl esters such as glycerol tribenzoate and glycerol 4-methylbenzoate, diglycerol tetraacetylate, diglycerol tetrapropionate, diglycerol acetate tricaprylate, diglycerol Tetralaurate, diglycerin alkyl ester, diglycerin tetracyclobutylcarboxylate, diglycerin tet Diglycerol cycloalkyl esters such as cyclopentyl carboxylate diglycerin tetrabenzoate, diglycerin aryl ester such as diglycerin 3-methylbenzoate or the like. These alkylate groups, cycloalkylcarboxylate groups, and arylate groups may be the same or different, and may be further substituted. Moreover, the mix of alkylate group, a cycloalkyl carboxylate group, and an arylate group may be sufficient, and these substituents may couple | bond together by the covalent bond. Furthermore, the glycerin and diglycerin part may be substituted, the partial structure of the glycerin ester and the diglycerin ester may be part of the polymer or regularly pendant, and the antioxidant, acid scavenger, You may introduce | transduce into a part of molecular structure of additives, such as a ultraviolet absorber.

  Specific examples of other polyhydric alcohol ester plasticizers include polyhydric alcohol ester plasticizers described in paragraphs 30 to 33 of JP-A No. 2003-12823.

  These alkylate groups, cycloalkylcarboxylate groups, and arylate groups may be the same or different, and may be further substituted. Moreover, the mix of alkylate group, a cycloalkyl carboxylate group, and an arylate group may be sufficient, and these substituents may couple | bond together by the covalent bond. Furthermore, the polyhydric alcohol part may be substituted, and the partial structure of the polyhydric alcohol may be part of the polymer or regularly pendant, and may be an antioxidant, an acid scavenger, an ultraviolet absorber. May be introduced into a part of the molecular structure of the additive.

  Among the ester plasticizers composed of the polyhydric alcohol and the monovalent carboxylic acid, alkyl polyhydric alcohol aryl esters are preferred. Specifically, the above-mentioned ethylene glycol dibenzoate, glycerin tribenzoate, diglycerin tetrabenzoate, Illustrative compound 16 described in paragraph 31 of Kaikai 2003-12823 and Illustrative compound 48 described in paragraph 64 of JP-A-2006-188663 may be mentioned.

  Specific examples of the dicarboxylic acid ester plasticizer that is one of the polyvalent carboxylic acid esters include alkyl dicarboxylic acid alkyl ester plasticizers such as didodecyl malonate, dioctyl adipate, and dibutyl sebacate. Alkyl dicarboxylic acid cycloalkyl ester type plasticizers such as cyclopentyl succinate and dicyclohexyl adipate, alkyl dicarboxylic acid aryl ester type plasticizers such as diphenyl succinate and di4-methylphenyl glutarate, dihexyl-1,4-cyclohexane Cycloalkyl dicarboxylic acid alkyl ester plasticizers such as dicarboxylate and didecylbicyclo [2.2.1] heptane-2,3-dicarboxylate, dicyclohexyl-1,2-cyclobutanedicarboxylate, dicis Cycloalkyldicarboxylic acid cycloalkyl ester plasticizers such as ropropyl-1,2-cyclohexyldicarboxylate, diphenyl-1,1-cyclopropyldicarboxylate, di2-naphthyl-1,4-cyclohexanedicarboxylate, etc. Cycloalkyldicarboxylic acid aryl ester plasticizer, diethyl phthalate, dimethyl phthalate, dioctyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate, and other aryl dicarboxylic acid alkyl ester plasticizers, dicyclopropyl phthalate, dicyclohexyl phthalate, etc. Aryl dicarboxylic acid cycloalkyl ester plasticizers such as diphenyl phthalate and di-4-methylphenyl phthalate And the like.

  These alkoxy groups and cycloalkoxy groups may be the same or different, may be mono-substituted, and these substituents may be further substituted. The alkyl group and cycloalkyl group may be mixed, or these substituents may be bonded together by a covalent bond. Furthermore, the aromatic ring of phthalic acid may be substituted, and a multimer such as a dimer, trimer or tetramer may be used. Also, the partial structure of phthalate ester may be part of the polymer or regularly pendant to the polymer, and it may be part of the molecular structure of additives such as antioxidants, acid scavengers, and UV absorbers. It may be introduced.

  The addition amount of the ester plasticizer comprising a polyhydric alcohol and a monovalent carboxylic acid, and the ester plasticizer comprising a polyhydric carboxylic acid and a monohydric alcohol is usually 0.1 to 100 parts by mass of the cellulose ester. 50 parts by mass, preferably 1-30 parts by mass, more preferably 3-15 parts by mass.

  Examples of other polycarboxylic acid ester plasticizers include alkyl polycarboxylic acid alkyl esters such as tridodecyl tricarbarate and tributyl-meso-butane-1,2,3,4-tetracarboxylate. Plasticizers, alkylpolycarboxylic acid cycloalkyl ester plasticizers such as tricyclohexyltricarbarate, tricyclopropyl-2-hydroxy-1,2,3-propanetricarboxylate, triphenyl 2-hydroxy- Alkyl polyvalent carboxylic acid aryl ester plasticizers such as 1,2,3-propanetricarboxylate, tetra-3-methylphenyltetrahydrofuran-2,3,4,5-tetracarboxylate, tetrahexyl-1,2, 3,4-cyclobutanetetracarboxylate, tetrabu Cycloalkyl polycarboxylic acid alkyl ester plasticizers such as ru-1,2,3,4-cyclopentanetetracarboxylate, tetracyclopropyl-1,2,3,4-cyclobutanetetracarboxylate, tricyclohexyl- Cycloalkyl polycarboxylic acid cycloalkyl ester plasticizers such as 1,3,5-cyclohexyl tricarboxylate, triphenyl-1,3,5-cyclohexyl tricarboxylate, hexa-4-methylphenyl-1,2, Cycloalkyl polycarboxylic acid aryl ester plasticizers such as 3,4,5,6-cyclohexylhexacarboxylate, tridodecylbenzene-1,2,4-tricarboxylate, tetraoctylbenzene-1,2,4 , 5-tetracarboxylate and other aryl polyvalent Rubinoic acid alkyl ester plasticizers, tricyclopentylbenzene-1,3,5-tricarboxylate, tetracyclohexylbenzene-1,2,3,5-tetracarboxylate and other aryl polyvalent carboxylic acid cycloalkyl esters Plasticizers of aryl polyvalent carboxylic acid aryl esters such as plasticizers triphenylbenzene-1,3,5-tetracarboxylate, hexa-4-methylphenylbenzene-1,2,3,4,5,6-hexacarboxylate Agents. These alkoxy groups and cycloalkoxy groups may be the same or different, and may be mono-substituted, and these substituents may be further substituted. The alkyl group and cycloalkyl group may be mixed, or these substituents may be bonded together by a covalent bond. Furthermore, the aromatic ring of phthalic acid may be substituted, and a multimer such as a dimer, trimer or tetramer may be used. Also, the partial structure of phthalate ester may be part of the polymer or regularly pendant into the polymer, and introduced into part of the molecular structure of additives such as antioxidants, acid scavengers, UV absorbers, etc. May be.

  Among the ester plasticizers composed of the polyvalent carboxylic acid and the monohydric alcohol, alkyl dicarboxylic acid alkyl esters are preferable, and specific examples include the dioctyl adipate.

  Examples of other plasticizers used in the present invention include phosphate ester plasticizers, carbohydrate ester plasticizers, and polymer plasticizers.

  Specific examples of the phosphoric acid ester plasticizer include phosphoric acid alkyl esters such as triacetyl phosphate and tributyl phosphate, phosphoric acid cycloalkyl esters such as tricyclobenthyl phosphate and cyclohexyl phosphate, triphenyl phosphate, tricresyl phosphate, Examples thereof include phosphoric acid aryl esters such as cresyl phenyl phosphate, octyl diphenyl phosphate, diphenyl biphenyl phosphate, trioctyl phosphate, tributyl phosphate, trinaphthyl phosphate, trixylyl phosphate, tris ortho-biphenyl phosphate. These substituents may be the same or different, and may be further substituted. Moreover, the mix of an alkyl group, a cycloalkyl group, and an aryl group may be sufficient, and substituents may couple | bond together by the covalent bond.

  Also, alkylene bis (dialkyl phosphate) such as ethylene bis (dimethyl phosphate), butylene bis (diethyl phosphate), alkylene bis (diaryl phosphate) such as ethylene bis (diphenyl phosphate), propylene bis (dinaphthyl phosphate), phenylene bis (dibutyl) And phosphate esters such as arylene bis (diaryl phosphate) such as arylene bis (dialkyl phosphate), phenylene bis (diphenyl phosphate), naphthylene bis (ditoluyl phosphate) such as biphenylene bis (dioctyl phosphate). These substituents may be the same or different, and may be further substituted. Moreover, the mix of an alkyl group, a cycloalkyl group, and an aryl group may be sufficient, and substituents may couple | bond together by the covalent bond.

  Furthermore, the partial structure of the phosphate ester may be part of the polymer or may be regularly pendant, and may be introduced into part of the molecular structure of additives such as antioxidants, acid scavengers, and UV absorbers. It may be. Among the above-mentioned compounds, phosphoric acid aryl ester and arylene bis (diaryl phosphate) are preferable, and specifically, triphenyl phosphate and phenylene bis (diphenyl phosphate) are preferable.

  Next, the carbohydrate ester plasticizer will be described. The carbohydrate means a monosaccharide, disaccharide or trisaccharide in which the saccharide is present in the form of pyranose or furanose (6-membered ring or 5-membered ring). Non-limiting examples of carbohydrates include glucose, saccharose, lactose, cellobiose, mannose, xylose, ribose, galactose, arabinose, fructose, sorbose, cellotriose and raffinose. The carbohydrate ester refers to an ester compound formed by dehydration condensation of a carbohydrate hydroxyl group and a carboxylic acid, and specifically means an aliphatic carboxylic acid ester or an aromatic carboxylic acid ester of a carbohydrate. Examples of the aliphatic carboxylic acid include acetic acid and propionic acid, and examples of the aromatic carboxylic acid include benzoic acid, toluic acid, and anisic acid. Carbohydrates have a number of hydroxyl groups depending on the type, but even if a part of the hydroxyl group reacts with the carboxylic acid to form an ester compound, the whole hydroxyl group reacts with the carboxylic acid to form an ester compound. Also good. In the present invention, it is preferable that all of the hydroxyl groups react with the carboxylic acid to form an ester compound.

  Specific examples of the carbohydrate ester plasticizer include glucose pentaacetate, glucose pentapropionate, glucose pentabtylate, saccharose octaacetate, saccharose octabenzoate, and of these, saccharose octaacetate is more preferable. preferable.

  Specific examples of the polymer plasticizer include aliphatic hydrocarbon polymers, polyethyl acrylate, polymethyl methacrylate, a copolymer of methyl methacrylate and 2-hydroxyethyl methacrylate, and methyl methacrylate and acrylic. Acrylic polymers such as copolymers of methyl acid and 2-hydroxyethyl methacrylate, vinyl polymers such as polyvinyl isobutyl ether, polybutylene succinate, polyesters such as polyethylene terephthalate, polyethylene naphthalate, polyethylene oxide, polypropylene Examples include polyethers such as oxides, polyamides, polyurethanes, and polyureas. The number average molecular weight is preferably about 1,000 to 500,000, particularly preferably 5,000 to 200,000. If it is 1000 or less, a problem arises in volatility, and if it exceeds 500000, the plasticizing ability is lowered, and the mechanical properties of the cellulose ester film are adversely affected.

  These polymer plasticizers may be a homopolymer composed of one type of repeating unit or a copolymer having a plurality of repeating structures. Two or more of the above polymers may be used in combination.

  The amount of the other plasticizer added is usually 0.1 to 50 parts by mass, preferably 1 to 30 parts by mass, and more preferably 3 to 15 parts by mass with respect to 100 parts by mass of the cellulose ester.

(Antioxidant)
In the optical film of the present invention, the decomposition of the optical film molding material by heat and oxygen is promoted under a high temperature environment at the time of melt film formation.

  Moreover, in this invention, it is also preferable to wash | clean in antioxidant presence at the time of suspension washing by the poor solvent of a cellulose ester. The antioxidant to be used is not limited as long as it is a compound that inactivates radicals generated in the cellulose ester or suppresses deterioration of the cellulose ester caused by addition of oxygen to the radical generated in the cellulose ester. be able to.

  The antioxidant used for suspension washing of the cellulose ester may remain in the cellulose ester after washing. The remaining amount is preferably 0.01 to 2000 ppm, more preferably 0.05 to 1000 ppm. More preferably, it is 0.1-100 ppm.

  The antioxidant useful in the present invention can be used without limitation as long as it is a compound that suppresses the deterioration of the optical film molding material due to oxygen. Among them, the useful antioxidants include phenolic compounds and hindered amine compounds. , Phosphorus compounds, sulfur compounds, heat-resistant processing stabilizers, oxygen scavengers and the like. Among these, phenol compounds, hindered amine compounds, and phosphorus compounds are particularly preferable.

  By blending these compounds, it is possible to prevent coloring and strength reduction of the molded product due to heat, thermal oxidation degradation, and the like without reducing transparency, heat resistance, and the like. These antioxidants can be used alone or in combination of two or more.

(Phenolic compounds)
Phenol compounds are known compounds and are described, for example, in columns 12 to 14 of US Pat. No. 4,839,405, and include 2,6-dialkylphenol derivative compounds. Among such compounds, preferred compounds are those represented by the following general formula (a).

In formula, R _{< a11 >} -R _<a16> represents a substituent. Examples of the substituent include a hydrogen atom, a halogen atom (eg, fluorine atom, chlorine atom, etc.), an alkyl group (eg, methyl group, ethyl group, isopropyl group, hydroxyethyl group, methoxymethyl group, trifluoromethyl group, t-butyl group). Etc.), cycloalkyl groups (eg cyclopentyl group, cyclohexyl group etc.), aralkyl groups (eg benzyl group, 2-phenethyl group etc.), aryl groups (eg phenyl group, naphthyl group, p-tolyl group, p-chlorophenyl group etc.) ), Alkoxy group (eg methoxy group, ethoxy group, isopropoxy group, butoxy group etc.), aryloxy group (eg phenoxy group etc.), cyano group, acylamino group (eg acetylamino group, propionylamino group etc.), alkylthio group (For example, methylthio group, ethylthio group, butylthio group, etc.) Arylthio group (for example, phenylthio group), sulfonylamino group (for example, methanesulfonylamino group, benzenesulfonylamino group, etc.), ureido group (for example, 3-methylureido group, 3,3-dimethylureido group, 1,3-dimethylureido) Group), sulfamoylamino group (dimethylsulfamoylamino group etc.), carbamoyl group (eg methylcarbamoyl group, ethylcarbamoyl group, dimethylcarbamoyl group etc.), sulfamoyl group (eg ethylsulfamoyl group, dimethylsulfamoyl group) Moyl group etc.), alkoxycarbonyl group (eg methoxycarbonyl group, ethoxycarbonyl group etc.), aryloxycarbonyl group (eg phenoxycarbonyl group etc.), sulfonyl group (eg methanesulfonyl group, butanesulfonyl group, phenyl) Sulfonyl group etc.), acyl group (eg acetyl group, propanoyl group, butyroyl group etc.), amino group (methylamino group, ethylamino group, dimethylamino group etc.), cyano group, hydroxy group, nitro group, nitroso group, amine Oxide group (for example, pyridine-oxide group), imide group (for example, phthalimide group, etc.), disulfide group (for example, benzene disulfide group, benzothiazolyl-2-disulfide group, etc.), carboxyl group, sulfo group, heterocyclic group (for example, pyrrole group) Pyrrolidyl group, pyrazolyl group, imidazolyl group, pyridyl group, benzimidazolyl group, benzthiazolyl group, benzoxazolyl group, etc.). These substituents may be further substituted.

In addition, a phenol compound in which R _a11 is a hydrogen atom, and R _a12 and R _a16 are t-butyl groups is preferable. Specific examples of the phenol compound include n-octadecyl 3- (3,5-di-t-butyl-4-hydroxyphenyl) -propionate, n-octadecyl 3- (3,5-di-t-butyl-4 -Hydroxyphenyl) -acetate, n-octadecyl 3,5-di-t-butyl-4-hydroxybenzoate, n-hexyl 3,5-di-t-butyl-4-hydroxyphenylbenzoate, n-dodecyl 3,5 -Di-t-butyl-4-hydroxyphenylbenzoate, neo-dodecyl 3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, dodecyl beta (3,5-di-t-butyl-4 -Hydroxyphenyl) propionate, ethyl α- (4-hydroxy-3,5-di-t-butylphenyl) isobutyrate, octadecyl α- (4-hydroxy-3,5-di-t-butylphenyl) isobutyrate, octadecyl α- (4-hydroxy-3,5-di-t-butyl-4-hydroxyphenyl) propionate, 2- (n- Octylthio) ethyl 3,5-di-t-butyl-4-hydroxy-benzoate, 2- (n-octylthio) ethyl 3,5-di-t-butyl-4-hydroxy-phenylacetate, 2- (n-octadecyl) Thio) ethyl 3,5-di-t-butyl-4-hydroxyphenyl acetate, 2- (n-octadecylthio) ethyl 3,5-di-t-butyl-4-hydroxy-benzoate, 2- (2-hydroxy Ethylthio) ethyl 3,5-di-t-butyl-4-hydroxybenzoate, diethyl glycol bis- (3,5-di-t-butyl-4- Droxy-phenyl) propionate, 2- (n-octadecylthio) ethyl 3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, stearamide N, N-bis- [ethylene 3- (3,5 -Di-t-butyl-4-hydroxyphenyl) propionate], n-butylimino N, N-bis- [ethylene 3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], 2- ( 2-stearoyloxyethylthio) ethyl 3,5-di-tert-butyl-4-hydroxybenzoate, 2- (2-stearoyloxyethylthio) ethyl 7- (3-methyl-5-tert-butyl-4-hydroxy) Phenyl) heptanoate, 1,2-propylene glycol bis- [3- (3,5-di-t-butyl-4-hydroxypheny ) Propionate], ethylene glycol bis- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], neopentyl glycol bis- [3- (3,5-di-t-butyl-4) -Hydroxyphenyl) propionate], ethylene glycol bis- (3,5-di-t-butyl-4-hydroxyphenylacetate), glycerin-ln-octadecanoate-2,3-bis- (3,5 -Di-t-butyl-4-hydroxyphenyl acetate), pentaerythritol-tetrakis- [3- (3 ', 5'-di-t-butyl-4'-hydroxyphenyl) propionate], 1,1,1- Trimethylolethane-tris- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], sorbitol Oxa- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 2-hydroxyethyl 7- (3-methyl-5-tert-butyl-4-hydroxyphenyl) propionate, 2- Stearoyloxyethyl 7- (3-methyl-5-t-butyl-4-hydroxyphenyl) heptanoate, 1,6-n-hexanediol-bis [(3 ', 5'-di-t-butyl-4-hydroxy Phenyl) propionate], pentaerythritol-tetrakis (3,5-di-t-butyl-4-hydroxyhydrocinnamate). Phenol compounds of the above type are commercially available, for example, from Ciba Specialty Chemicals under the trade names “IRGANOX 1076” and “IRGANOX 1010”.

(Hindered amine compounds)
As one of the antioxidants useful in the present invention, a hindered amine compound represented by the following general formula (b) is preferable.

In formula, R _{< b11 >} -R _<b17> represents a substituent. As a substituent, it is synonymous with the substituent represented by R _{< a11 >} -R _<a16> of the said general formula (a). R _b13 is a hydrogen atom, methyl _{group, R b16} is a hydrogen _{atom, R b11, R b12, R} b14, R b15 is preferably a methyl group.

  Specific examples of hindered amine compounds include bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (2,2,6,6-tetramethyl-4-piperidyl) succinate, bis (1 , 2,2,6,6-pentamethyl-4-piperidyl) sebacate, bis (N-octoxy-2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (N-benzyloxy-2,2) , 6,6-tetramethyl-4-piperidyl) sebacate, bis (N-cyclohexyloxy-2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (1,2,2,6,6- Pentamethyl-4-piperidyl) 2- (3,5-di-t-butyl-4-hydroxybenzyl) -2-butylmalonate, bis (1-acryloyl-2,2,6,6- Tramethyl-4-piperidyl) 2,2-bis (3,5-di-tert-butyl-4-hydroxybenzyl) -2-butylmalonate, bis (1,2,2,6,6-pentamethyl-4- Piperidyl) decanedioate, 2,2,6,6-tetramethyl-4-piperidyl methacrylate, 4- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxy] -1- [ 2- (3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxy) ethyl] -2,2,6,6-tetramethylpiperidine, 2-methyl-2- (2,2, 6,6-tetramethyl-4-piperidyl) amino-N- (2,2,6,6-tetramethyl-4-piperidyl) propionamide, tetrakis (2,2,6,6-tetramethyl-4-piperidyl) 1,2,3,4-butane tetracarboxylate, tetrakis (1,2,2,6,6-pentamethyl-4-piperidyl) 1,2,3,4-butane tetracarboxylate, and the like.

  Further, it may be a polymer type compound. As specific examples, N, N ′, N ″, N ″ ′-tetrakis- [4,6-bis- [butyl- (N-methyl-2,2,6, 6-tetramethylpiperidin-4-yl) amino] -triazin-2-yl] -4,7-diazadecane-1,10-diamine, dibutylamine and 1,3,5-triazine-N, N′-bis ( 2,2,6,6-tetramethyl-4-piperidyl) -1,6-hexamethylenediamine and N- (2,2,6,6-tetramethyl-4-piperidyl) butylamine polycondensate, di Polycondensate of butylamine, 1,3,5-triazine and N, N′-bis (2,2,6,6-tetramethyl-4-piperidyl) butylamine, poly [{(1,1,3,3 -Tetramethylbutyl) amino-1,3,5-tri Gin-2,4-diyl} {(2,2,6,6-tetramethyl-4-piperidyl) imino} hexamethylene {(2,2,6,6-tetramethyl-4-piperidyl) imino}], Between 1,6-hexanediamine-N, N'-bis (2,2,6,6-tetramethyl-4-piperidyl) and morpholine-2,4,6-trichloro-1,3,5-triazine Polycondensate, poly [(6-morpholino-s-triazine-2,4-diyl) [(2,2,6,6-tetramethyl-4-piperidyl) imino] -hexamethylene [(2,2,6 , 6-tetramethyl-4-piperidyl) imino]], etc., high molecular weight HALS in which a plurality of piperidine rings are bonded via a triazine skeleton; dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl- 1-piperidine ester Polymer with diol, 1,2,3,4-butanetetracarboxylic acid, 1,2,2,6,6-pentamethyl-4-piperidinol and 3,9-bis (2-hydroxy-1,1-dimethyl) (Ethyl) -2,4,8,10-tetraoxaspiro [5,5] undecane and the like, and the like are exemplified by compounds in which a piperidine ring is bonded through an ester bond, but the present invention is not limited thereto. It is not a thing.

  Among these, polycondensates of dibutylamine, 1,3,5-triazine and N, N′-bis (2,2,6,6-tetramethyl-4-piperidyl) butylamine, poly [{(1, 1,3,3-tetramethylbutyl) amino-1,3,5-triazine-2,4-diyl} {(2,2,6,6-tetramethyl-4-piperidyl) imino} hexamethylene {(2 , 2,6,6-tetramethyl-4-piperidyl) imino}], a polymer of dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol, etc. Those having a molecular weight (Mn) of 2,000 to 5,000 are preferred.

  Hindered phenol compounds of the above type are commercially available, for example, from Ciba Specialty Chemicals under the trade names “TINUVIN 144” and “TINUVIN 770” and “ADK STAB LA-52” from Asahi Denka Kogyo Co., Ltd.

(Phosphorus compounds)
As one of the antioxidants useful in the present invention, a moiety represented by the following general formulas (c-1), (c-2), (c-3), (c-4), (c-5) A compound having a structure in the molecule is preferred.

In the formula, Ph ₁ and Ph ′ ₁ represent a divalent substituent. More preferably, Ph ₁ and Ph ′ ₁ represent a phenylene group, and the hydrogen atom of the phenylene group is a phenyl group, an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group having 5 to 8 carbon atoms, or 6 to 12 carbon atoms. Or an alkyl cycloalkyl group or an aralkyl group having 7 to 12 carbon atoms.

Ph ₁ and Ph ′ ₁ may be the same as or different from each other. X represents a single bond, a sulfur atom or a —CHR ₆ — group. R ₆ represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or a cycloalkyl group having 5 to 8 carbon atoms. These may be substituted with a substituent having the same meaning as the substituent represented by R _{11 to} R ₁₆ in the general formula (a).

Wherein, Ph ₂ and Ph _'2 each represent a substituent. As a substituent, it is synonymous with the substituent represented by R _{< a11 >} -R _<a16> of the said general formula (a). More preferably, Ph ₂ and Ph ′ ₂ represent a phenyl group or a biphenyl group, and the hydrogen atom of the phenyl group or biphenyl group is an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group having 5 to 8 carbon atoms, or a carbon number. It may be substituted with a 6-12 alkylcycloalkyl group or an aralkyl group having 7-12 carbon atoms.

Ph ₂ and Ph ′ ₂ may be the same as or different from each other. These may be substituted with a substituent having the same _meaning as the substituent represented by R _{a11 to} R _a16 in the general formula (a).

In the formula, Ph ₃ represents a substituent. As a substituent, it is synonymous with the substituent represented by R _{< a11 >} -R _<a16> of the said general formula (a). More preferably, Ph ₃ represents a phenyl group or a biphenyl group, and the hydrogen atom of the phenyl group or biphenyl group is an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group having 5 to 8 carbon atoms, or a 6 to 12 carbon atom. It may be substituted with an alkylcycloalkyl group or an aralkyl group having 7 to 12 carbon atoms.

These may be substituted with a substituent having the same _meaning as the substituent represented by R _{a11 to} R _a16 in the general formula (a).

In the formula, Ph ₄ represents a substituent. As a substituent, it is synonymous with the substituent represented by R _{< a11 >} -R _<a16> of the said general formula (a). More preferably, Ph ₄ represents an alkyl group having 1 to 20 carbon atoms or a phenyl group, and the alkyl group or phenyl group is a substituent having the same _meaning as the substituent represented by R _{a11 to} R _a16 in the general formula (a). It may be substituted by a group.

In the formula, Ph ₅ , Ph ′ ₅ and Ph ″ ₅ represent substituents. The substituents have the same _meaning as the substituents represented by R _{a11 to} R _a16 in the general formula (a). More preferably, Ph ₅ , Ph ′ ₅ and Ph ″ ₅ represent an alkyl group or phenyl group having 1 to 20 carbon atoms, and the alkyl group or phenyl group is a substituent represented by R _{a11 to} R _a16 in the general formula (a). It may be substituted with a substituent having the same meaning as

  Specific examples of phosphorus compounds include triphenyl phosphite, diphenylisodecyl phosphite, phenyl diisodecyl phosphite, tris (nonylphenyl) phosphite, tris (dinonylphenyl) phosphite, tris (2,4-di-). t-butylphenyl) phosphite, 10- (3,5-di-t-butyl-4-hydroxybenzyl) -9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 6- [ 3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propoxy] -2,4,8,10-tetra-tert-butyldibenz [d, f] [1.3.2] dioxaphosphine Monophosphite compounds such as pin and tridecyl phosphite; 4,4'-butylidene-bis (3-methyl-6-t-butyl) Diphosphite compounds such as phenyl-di-tridecyl phosphite), 4,4'-isopropylidene-bis (phenyl-di-alkyl (C12-C15) phosphite); triphenylphosphonite, tetrakis (2,4- Di-tert-butylphenyl) [1,1-biphenyl] -4,4'-diylbisphosphonite, tetrakis (2,4-di-tert-butyl-5-methylphenyl) [1,1-biphenyl]- Phosphonite compounds such as 4,4'-diylbisphosphonite; phosphinite compounds such as triphenylphosphinite and 2,6-dimethylphenyldiphenylphosphinite; triphenylphosphine and tris (2,6-dimethoxyphenyl) Phosphine compounds such as phosphine; and the like. In particular, phosphonite compounds are preferred.

  Phosphorus compounds of the above type are, for example, from Sumitomo Chemical Co., Ltd., “Sumilizer GP”, from ADEKA Co., Ltd., “ADK STAB PEP-24G”, “ADK STAB PEP-36” and “ADK STAB 3010”, Ciba Japan It is commercially available under the trade name “IRGAFOS P-EPQ” from the company and “GSY-P101” from Sakai Chemical Industry.

  Moreover, the following compound is mentioned.

(Sulfur compounds)
As one of the antioxidants useful in the present invention, a sulfur compound represented by the following general formula (d) is preferable.

In formula, _Rd11 and _Rd12 represent a substituent. As a substituent, it is synonymous with the substituent represented by R _{< a11 >} -R _<a16> of the said general formula (a).

  Specific examples of the sulfur compound include dilauryl 3,3-thiodipropionate, dimyristyl 3,3'-thiodipropionate, distearyl 3,3-thiodipropionate, lauryl stearyl 3,3-thiodipropioate. And pentaerythritol-tetrakis (β-lauryl-thio-propionate), 3,9-bis (2-dodecylthioethyl) -2,4,8,10-tetraoxaspiro [5,5] undecane and the like. .

  The above-mentioned type of sulfur-based compound is commercially available from Sumitomo Chemical Co., Ltd. under the trade names “Sumilizer TPL-R” and “Sumilizer TP-D”, for example.

  Examples of heat-resistant processing stabilizers include 2-t-butyl-6- (3-t-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate, 2- [1- (2-hydroxy- 3,5-di-t-pentylphenyl) ethyl] -4,6-di-t-pentylphenyl acrylate and the like. The above types of heat-resistant processing stabilizers are commercially available from Sumitomo Chemical Co., Ltd. under the trade names “Sumilizer GM” and “Sumilizer GS”.

  The antioxidant is preferably removed from impurities such as residual acids, inorganic salts, organic low molecules, etc. that are carried over from production or generated during storage, and more preferably has a purity of 99% or more, like the cellulose ester described above. It is. The residual acid and water are preferably 0.01 to 100 ppm. When melt-forming cellulose ester, thermal degradation can be suppressed, and film-forming stability, optical properties of the film, and mechanical properties are improved.

  The antioxidant is preferably added in an amount of 0.1 to 10% by mass, more preferably 0.2 to 5% by mass, and further preferably 0.5 to 2% by mass. Two or more of these may be used in combination.

  If the addition amount of the antioxidant is too small, the stabilizing effect is low at the time of melting, so the effect cannot be obtained, and if the addition amount is too large, the transparency as a film is lowered from the viewpoint of compatibility with the cellulose ester. Cause the film to become brittle.

  In the optical film of the present invention, the decomposition of the optical film-forming material due to heat at the time of melt film formation is suppressed, the decrease in contrast is prevented, and the surface processability is improved. Therefore, the compound represented by the following general formula (e) Is preferably added.

In the general formula (e), R _{e12 to} R _e15 each independently represent a hydrogen atom or a substituent. The substituent represented by R _{e12 to} R _e15 is not particularly limited, and examples thereof include alkyl groups (for example, methyl group, ethyl group, propyl group, isopropyl group, t-butyl group, pentyl group, hexyl group, octyl group). Group, dodecyl group, trifluoromethyl group, etc.), cycloalkyl group (eg, cyclopentyl group, cyclohexyl group, etc.), aryl group (eg, phenyl group, naphthyl group, etc.), acylamino group (eg, acetylamino group, benzoylamino) Group), alkylthio group (for example, methylthio group, ethylthio group, etc.), arylthio group (for example, phenylthio group, naphthylthio group, etc.), alkenyl group (for example, vinyl group, 2-propenyl group, 3-butenyl group, 1- Methyl-3-propenyl group, 3-pentenyl group, 1-methyl-3-butenyl group, 4-hexyl Senyl group, cyclohexenyl group, etc.), halogen atom (eg, fluorine atom, chlorine atom, bromine atom, iodine atom, etc.), alkynyl group (eg, propargyl group, etc.), heterocyclic group (eg, pyridyl group, thiazolyl group, etc.) Oxazolyl group, imidazolyl group, etc.), alkylsulfonyl group (eg, methylsulfonyl group, ethylsulfonyl group, etc.), arylsulfonyl group (eg, phenylsulfonyl group, naphthylsulfonyl group, etc.), alkylsulfinyl group (eg, methylsulfinyl group, etc.) ), Arylsulfinyl group (for example, phenylsulfinyl group), phosphono group, acyl group (for example, acetyl group, pivaloyl group, benzoyl group, etc.), carbamoyl group (for example, aminocarbonyl group, methylaminocarbonyl group, dimethylaminocarbonyl) Base Butylaminocarbonyl group, cyclohexylaminocarbonyl group, phenylaminocarbonyl group, 2-pyridylaminocarbonyl group, etc.), sulfamoyl group (for example, aminosulfonyl group, methylaminosulfonyl group, dimethylaminosulfonyl group, butylaminosulfonyl group, hexylaminosulfonyl group) Group, cyclohexylaminosulfonyl group, octylaminosulfonyl group, dodecylaminosulfonyl group, phenylaminosulfonyl group, naphthylaminosulfonyl group, 2-pyridylaminosulfonyl group, etc., sulfonamide group (for example, methanesulfonamide group, benzenesulfonamide group) ), Cyano group, alkoxy group (for example, methoxy group, ethoxy group, propoxy group, etc.), aryloxy group (for example, phenoxy group, naphthyloxy) Si group etc.), heterocyclic oxy group, siloxy group, acyloxy group (eg acetyloxy group, benzoyloxy group etc.), sulfonic acid group, salt of sulfonic acid, aminocarbonyloxy group, amino group (eg amino group, Ethylamino group, dimethylamino group, butylamino group, cyclopentylamino group, 2-ethylhexylamino group, dodecylamino group, etc.), anilino group (for example, phenylamino group, chlorophenylamino group, toluidino group, anisidino group, naphthylamino group) 2-pyridylamino group, etc.), imide group, ureido group (for example, methylureido group, ethylureido group, pentylureido group, cyclohexylureido group, octylureido group, dodecylureido group, phenylureido group, naphthylureido group, 2- Pyridylaminoureido group ), Alkoxycarbonylamino group (eg, methoxycarbonylamino group, phenoxycarbonylamino group, etc.), alkoxycarbonyl group (eg, methoxycarbonyl group, ethoxycarbonyl group, phenoxycarbonyl, etc.), aryloxycarbonyl group (eg, phenoxycarbonyl group) Etc.), heterocyclic thio groups, thioureido groups, carboxyl groups, carboxylic acid salts, hydroxyl groups, mercapto groups, nitro groups and the like. These substituents may be further substituted with the same substituent.

In the general formula (e), R _{e12 to} R _e15 are preferably a hydrogen atom or an alkyl group.

In the general formula (e), R _e16 represents a hydrogen atom or a substituent, and _examples of the substituent represented by R _e16 include the same groups as the substituents represented by R _{e12 to} R _e15 .

In the general formula (e), R _e16 is preferably a hydrogen atom.

  In the general formula (e), ne represents 1 or 2.

In the general formula (e), when ne is 1, R _e11 represents a substituent, and when ne is 2, R _e11 represents a divalent linking group.

When R _e11 represents a substituent, _examples of the substituent include the same groups as the substituents represented by R _{e12 to} R _e15 . When _Re11 represents a divalent linking group, examples of the divalent linking group include an alkylene group that may have a substituent, an arylene group that may have a substituent, an oxygen atom, a nitrogen atom, and a sulfur atom. Or a combination of these linking groups.

In the general formula (e), ne is preferably 1, and R _e11 at that time is preferably a substituted or unsubstituted phenyl group, and more preferably a phenyl group substituted with an alkyl group or an acyloxy group.

  Next, although the specific example of a compound represented by the said general formula (e) in this invention is shown, this invention is not limited by the following specific examples.

  These compounds can be used singly or in combination of two or more, and the blending amount thereof is appropriately selected within a range not impairing the object of the present invention. It is 001-10.0 mass parts, Preferably it is 0.01-5.0 mass parts, More preferably, it is 0.1-3.0 mass parts.

(UV absorber)
The ultraviolet absorber is excellent in the ability to absorb ultraviolet rays having a wavelength of 370 nm or less from the viewpoint of preventing deterioration of the polarizer and the display device with respect to ultraviolet rays, and has little absorption of visible light having a wavelength of 400 nm or more from the viewpoint of liquid crystal display properties. Those are preferred.

  Examples of the ultraviolet absorber used in the present invention include oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, nickel complex compounds, triazine compounds, and the like. However, benzophenone compounds, less colored benzotriazole compounds, and triazine compounds are preferable.

  Further, ultraviolet absorbers described in JP-A Nos. 10-182621 and 8-337574, and polymer ultraviolet absorbers described in JP-A Nos. 6-148430 and 2003-113317 may be used.

  Specific examples of the benzotriazole ultraviolet absorber include 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-tert-butylphenyl) benzo Triazole, 2- (2'-hydroxy-3'-tert-butyl-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5'-di-tert-butylphenyl) -5 Chlorobenzotriazole, 2- (2′-hydroxy-3 ′-(3 ″, 4 ″, 5 ″, 6 ″ -tetrahydrophthalimidomethyl) -5′-methylphenyl) benzotriazole, 2,2-methylenebis (4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol), 2- (2'-hydroxy- '-Tert-butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-3'-tert-butyl-5'-(2-octyloxycarbonylethyl) -phenyl) -5 -Chlorobenzotriazole, 2- (2'-hydroxy-3 '-(1-methyl-1-phenylethyl) -5'-(1,1,3,3, -tetramethylbutyl) -phenyl) benzotriazole, 2- (2H-benzotriazol-2-yl) -6- (linear and side chain dodecyl) -4-methylphenol, octyl-3- [3-tert-butyl-4-hydroxy-5- (chloro-2H) -Benzotriazol-2-yl) phenyl] propionate and 2-ethylhexyl-3- [3-tert-butyl-4-hydroxy-5- (5-chloro- H- benzotriazol-2-yl) can be mentioned mixtures of phenyl] propionate, and the like.

  Further, as commercially available products, TINUVIN 171, TINUVIN 900, TINUVIN 928, TINUVIN 360 (all manufactured by Ciba Japan Co., Ltd.), LA31 (manufactured by ADEKA Corporation), RUVA-100 (made by Otsuka Chemical) is mentioned.

  Specific examples of benzophenone compounds include 2,4-dihydroxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone, bis (2-methoxy-4-hydroxy- 5-benzoylphenylmethane) and the like, but are not limited thereto.

  In this invention, it is preferable to add 0.1-5 mass% of ultraviolet absorbers with respect to resin, Furthermore, it is preferable to add 0.2-3 mass%, Furthermore, 0.5-2 mass% is added. It is preferable. Two or more of these may be used in combination.

  The benzotriazole structure or triazine structure may be part of the polymer, or may be regularly pendant to the polymer, and part of the molecular structure of other additives such as plasticizers, antioxidants, and acid scavengers. May be introduced.

  Although it does not specifically limit as a conventionally well-known ultraviolet absorptive polymer, For example, the polymer which homopolymerized RUVA-93 (made by Otsuka Chemical), the polymer which copolymerized RUVA-93, and another monomer, etc. are mentioned. .

  Specific examples include PUVA-30M obtained by copolymerization of RUVA-93 and methyl methacrylate at a ratio (mass ratio) of 3: 7, and PUVA-50M obtained by copolymerization at a ratio of 5: 5 (mass ratio). It is done. Furthermore, the polymer etc. which are described in Unexamined-Japanese-Patent No. 2003-113317 are mentioned.

(Matting agent)
Further, it is preferable to add fine particles as a matting agent to the optical film of the present invention. As fine particles used in the present invention, for example, silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, Mention may be made of aluminum silicate, magnesium silicate and calcium phosphate.

  The average primary particle diameter of the silicon dioxide fine particles is preferably 5 to 16 nm, and more preferably 5 to 12 nm. A smaller primary particle average diameter is preferred because haze is low. The apparent specific gravity is preferably 90 to 200 g / L, more preferably 100 to 200 g / L. A larger apparent specific gravity is preferable because a high-concentration dispersion can be produced, and haze and aggregates are improved.

The amount of the matting agent added is preferably 0.01 to 1.0 g, more preferably 0.03 to 0.3 g, and particularly preferably 0.10 to 0.18 g per 1 m ² .

  Examples of the silicon dioxide fine particles include AEROSIL R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, TT600, and NAX50 manufactured by Nippon Aerosil Co., Ltd., KE-P10 manufactured by Nippon Shokubai Co., Ltd. KE-P30, KE-P100, KE-P150, etc. Among them, AEROSIL200V, R972V is a fine particle of silicon dioxide having a primary average particle diameter of 20 nm or less and an apparent specific gravity of 70 g / L or more, This is particularly preferable because the effect of lowering the coefficient of friction is large while keeping the turbidity of the optical film low. Further, NAX50, KE-P30, and KE-P100 are particularly preferable because they have a large effect of reducing the friction coefficient in a small amount.

  The fine particles of zirconium oxide are commercially available under the trade names of Aerosil R976 and R811 (manufactured by Nippon Aerosil Co., Ltd.) and can be used. Examples of the polymer include silicone resin, fluorine resin, 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.

  These fine particles usually preferably form secondary particles having an average particle diameter of 0.01 to 1.0 μm, more preferably 0.1 to 0.8 μm, and most preferably 0.2 to 0.5 μm. These fine particles exist as aggregates of primary particles in the film, and form irregularities of 0.01 to 1.0 μm on the film surface. The content of these fine particles is preferably 0.005 to 0.3% by mass, more preferably 0.05 to 0.2% by mass, and most preferably 0.1 to 0.2% by mass with respect to the cellulose ester film. . Two or more kinds of these fine particles may be used in combination.

(Retardation control agent)
In order to improve the liquid crystal display quality, the optical film of the present invention is provided with a retardation control agent in the film, or an alignment film is formed to provide a liquid crystal layer, and the polarizing plate protective film and the retardation derived from the liquid crystal layer are provided. The optical compensation ability can be imparted by combining the above. As the compound to be added for adjusting the retardation, an aromatic compound having two or more aromatic rings as described in EP 911,656A2 may be used as a retardation control agent. it can. Or the rod-shaped compound of Unexamined-Japanese-Patent No. 2006-2025 is mentioned. Two or more aromatic compounds may be used in combination. The aromatic ring of the aromatic compound is particularly preferably an aromatic heterocyclic ring including an aromatic heterocyclic ring in addition to an aromatic hydrocarbon ring, and the aromatic heterocyclic ring is generally an unsaturated hetero ring. It is a ring. Of these, the 1,3,5-triazine ring described in JP-A-2006-2026 is particularly preferable.

(Acid scavenger)
The acid scavenger is an agent that plays a role of trapping an acid (protonic acid) remaining in the cellulose ester brought in from the production. Further, when the cellulose ester is melted, side chain hydrolysis is accelerated by moisture and heat in the polymer, and if it is cellulose acetate propionate, acetic acid and propionic acid are produced. A compound having an epoxy structure, a tertiary amine, an ether structure, or the like may be used as long as it can be chemically bonded to an acid, but is not limited thereto.

  Specifically, it is preferable to comprise an epoxy compound as an acid scavenger described in US Pat. No. 4,137,201. Epoxy compounds as such acid scavengers are known in the art and are derived by condensation of diglycidyl ethers of various polyglycols, particularly about 8-40 moles of ethylene oxide per mole of polyglycol. Metal glycol compounds such as polyglycols, diglycidyl ethers of glycerol (eg, those conventionally used in and together with vinyl chloride polymer compositions), epoxidized ether condensation products, bisphenol A Diglycidyl ether (ie, 4,4'-dihydroxydiphenyldimethylmethane), epoxidized unsaturated fatty acid ester (especially an ester of an alkyl of about 2 to 2 carbon atoms of a fatty acid of 2 to 22 carbon atoms (e.g. Butyl epoxy stearate ), And various epoxidized long chain fatty acid triglycerides and the like (e.g., epoxidized vegetable oils and other unsaturated natural oils, which may be represented and exemplified by compositions such as epoxidized soybean oil, sometimes epoxidized natural) These are referred to as glycerides or unsaturated fatty acids, which generally contain 12 to 22 carbon atoms)). Particularly preferred are commercially available epoxy group-containing epoxide resin compounds EPON 815c and other epoxidized ether oligomer condensation products of general formula (f).

  In the above formula, nf is equal to 0-12. Further possible acid scavengers that can be used include those described in paragraphs 87 to 105 of JP-A-5-194788.

  It is preferable that the acid scavenger removes impurities such as residual acid, inorganic salt, and low molecular weight organic substances that are carried over from production or generated during storage, and more preferably has a purity of 99%. That's it. The residual acid and water are preferably 0.01 to 100 ppm, and when melt-forming the cellulose resin, thermal degradation can be suppressed, and film-forming stability, optical properties of the film, and mechanical properties are improved. .

  The acid scavenger may be referred to as an acid scavenger, an acid scavenger, an acid catcher, etc., but can be used in the present invention without any difference due to their names.

(Melt casting method)
The optical film of the present invention is produced by a melt casting method.

  Since the melt casting method can significantly reduce the amount of organic solvent used during film production, the film is much more environmentally friendly than conventional solution casting methods that use large amounts of organic solvents. Therefore, it is preferable to produce an optical film by a melt casting method.

  The melt casting in the present invention is a method in which cellulose ester is heated and melted to a temperature at which the cellulose ester exhibits fluidity substantially without using a solvent, and a film is formed using this. For example, fluid cellulose ester is removed from a die. This is a method of forming a film by extrusion.

  In addition, although a solvent may be used in a part of the process of preparing the molten cellulose ester, in the melt film forming process in which the film is formed into a film, the forming process is substantially performed without using the solvent.

  More specifically, the molding method by melt casting can be classified into a melt extrusion molding method, a press molding method, an inflation method, an injection molding method, a blow molding method, a stretch molding method, and the like. Among these, the melt extrusion method is excellent for obtaining an optical film having excellent mechanical strength, surface accuracy, and the like. Hereinafter, the manufacturing method of the optical film of the present invention will be described by taking the melt extrusion method as an example.

  FIG. 1 is a schematic flow sheet diagram showing an example of one embodiment of an apparatus for carrying out the method for producing an optical film of the present invention.

  FIG. 2 is a flow sheet showing an example of an enlarged main part of the manufacturing apparatus of FIG.

  The optical film is produced by mixing an optical film material such as a cellulose resin, and then using the extruder 1 to melt and extrude from the casting die 4 onto the first cooling roll 5 so as to circumscribe the first cooling roll 5. In addition, the optical film 10 is obtained by sequentially circumscribing a total of three cooling rolls, that is, the second cooling roll 7 and the third cooling roll 8, and cooling and solidifying.

  Next, the optical film 10 peeled off by the peeling roll 9 is then stretched in the width direction by holding both ends of the optical film by the stretching device 12, and then wound by the winding device 16.

  Moreover, 6 which clamps a molten film on the surface of the 1st cooling roll 5 in order to correct flatness is provided. The touch roll 6 has an elastic surface and forms a nip with the first cooling roll 5. Details of the touch roll 6 will be described later.

  In the method for producing an optical film, the conditions for melt extrusion can be performed in the same manner as the conditions used for other thermoplastic resins such as polyester. The material is preferably dried beforehand. It is desirable to dry the moisture to 1000 ppm or less, preferably 200 ppm or less by using a vacuum or reduced pressure drier or a dehumidifying hot air drier.

  For example, the cellulose ester resin dried under hot air, vacuum or reduced pressure is melted at an extrusion temperature of about 200 to 300 ° C. using the extruder 1, filtered through a leaf disk type filter 2, etc. to remove foreign matters.

  When introducing into the extruder 1 from a supply hopper (not shown), it is preferable to prevent oxidative decomposition or the like under vacuum, reduced pressure, or inert gas atmosphere.

  When additives such as a plasticizer are not mixed in advance, they may be kneaded in the middle of the extruder. In order to add uniformly, it is preferable to use a mixing apparatus such as a static mixer.

  In the present invention, the cellulose resin and other additives such as a stabilizer added as necessary are preferably mixed before melting, and more preferably mixed before heating and the cellulose resin. . Mixing may be performed by a mixer or the like, or may be mixed in the cellulose resin preparation process as described above. When a mixer is used, a general mixer such as a V-type mixer, a conical screw type mixer, a horizontal cylindrical type mixer, a Henschel mixer, a ribbon mixer, or the like can be used.

  After mixing the optical film constituting material as described above, the mixture may be directly melted and formed into a film using the extruder 1, but once the optical film constituting material is pelletized, the pellet May be melted by the extruder 1 to form a film.

  Further, when the optical film constituting material includes a plurality of materials having different melting points, a so-called braided semi-melt is once produced at a temperature at which only a material having a low melting point is melted, and the semi-melt is extruded into the extruder 1. It is also possible to form a film by putting it into the film.

  If the optical film material contains materials that are easily pyrolyzed, in order to reduce the number of melting times, a method of directly forming a film without producing pellets, or making a braided semi-melt as described above A method of forming a film from is preferred.

  As the extruder 1, various commercially available extruders can be used, but a melt-kneading extruder is preferable, and a single-screw extruder or a twin-screw extruder may be used.

  When forming a film directly without producing pellets from the optical film constituent material, it is preferable to use a twin screw extruder because an appropriate degree of kneading is required. However, even with a single screw extruder, the screw shape can be changed to Maddock. By changing to a kneading type screw such as a mold, unimelt, dalmage, etc., moderate kneading can be obtained, which can be used. When a pellet or braided semi-melt is used as the optical film constituent material, it can be used with either a single screw extruder or a twin screw extruder.

  In the extruder 1 and the cooling step after extrusion, it is preferable to reduce the oxygen concentration by replacing with an inert gas such as nitrogen gas or reducing the pressure.

  The melting temperature of the optical film constituting material in the extruder 1 varies depending on the viscosity and discharge amount of the optical film constituting material, the thickness of the sheet to be produced, etc., but is preferably 150 to 300 ° C, more preferably 180 to 270 ° C. Preferably, 200-250 degreeC is more preferable. The melt viscosity at the time of extrusion is 10 to 100,000 poise, preferably 100 to 10,000 poise. Further, the residence time of the optical film constituting material in the extruder 1 is preferably shorter, and is within 5 minutes, preferably within 3 minutes, and more preferably within 2 minutes.

  Although the residence time depends on the type of the extruder 1 and the extrusion conditions, it can be shortened by adjusting the material supply amount, L / D, screw rotation speed, screw groove depth, etc. It is.

  The shape, rotation speed, etc. of the screw of the extruder 1 are appropriately selected depending on the viscosity, discharge amount, etc. of the optical film constituting material. In the present invention, the shear rate in the extruder 1 is 1 / second to 10000 / second, preferably 5 / second to 1000 / second, more preferably 10 / second to 100 / second.

  The extruder 1 that can be used in the present invention is generally available as a plastic molding machine.

  The optical film constituting material extruded from the extruder 1 is sent to the casting die 4 and extruded from the slit of the casting die 4 into an optical film shape. The casting die 4 is not particularly limited as long as it is used for producing a sheet or an optical film.

  The material of the casting die 4 is sprayed or plated with hard chromium, chromium carbide, chromium nitride, titanium carbide, titanium carbonitride, titanium nitride, super steel, ceramic (tungsten carbide, aluminum oxide, chromium oxide), etc. Processing such as buffing, lapping using a # 1000 or higher grinding wheel, plane cutting using a # 1000 or higher diamond grinding wheel (the cutting direction is perpendicular to the resin flow direction), electrolytic polishing, electrolytic composite polishing, etc. And the like. A preferred material for the lip portion of the casting die 4 is the same as that of the casting die 4. The surface accuracy of the lip is preferably 0.5S or less, and more preferably 0.2S or less.

  The slit of the casting die 4 is configured so that the gap can be adjusted.

  FIG. 3A is an external view showing an example of the main part of the casting die, and FIG. 3B is a cross-sectional view showing an example of the main part of the casting die.

  Of the pair of lips forming the slit 32 of the casting die 4, one is a flexible lip 33 having low rigidity and easily deformed, and the other is a fixed lip 34.

  A large number of heat bolts 35 are arranged at a constant pitch in the width direction of the casting die 4, that is, in the length direction of the slits 32. Each heat bolt 5 is provided with a block 36 having an embedded electric heater 37 and a cooling medium passage, and each heat bolt 35 penetrates each block 36 vertically.

  The base of the heat bolt 35 is fixed to the die body 31, and the tip is in contact with the outer surface of the flexible lip 33. While the block 36 is always air-cooled, the input of the embedded electric heater 37 is increased or decreased to raise or lower the temperature of the block 36, thereby causing the heat bolt 35 to thermally expand and contract, thereby displacing the flexible lip 33 to change the thickness of the optical film. Adjust.

  Thickness gauges are installed at the required locations in the wake of the die, and the web thickness information detected thereby is fed back to the control device. The thickness information is compared with the set thickness information by the control device, and correction control comes from the same device. It is also possible to control the power or the ON rate of the heat bolt heating element by the amount signal.

  The heat bolt preferably has a length of 20 to 40 cm and a diameter of 7 to 14 mm, and a plurality of, for example, several tens of heat bolts are preferably arranged at a pitch of 20 to 40 mm.

  Instead of the heat bolt, a gap adjusting member mainly composed of a bolt for adjusting the slit gap by manually moving back and forth in the axial direction may be provided.

  The slit gap adjusted by the gap adjusting member is usually 200 to 1000 μm, preferably 300 to 800 μm, more preferably 400 to 600 μm.

  The first to third cooling rolls are made of seamless steel pipe having a wall thickness of about 20 to 30 mm, and the surface is finished to a mirror surface. A pipe for flowing a cooling liquid is arranged inside the pipe, and the cooling liquid flowing through the pipe can absorb heat from the optical film on the roll.

  On the other hand, the touch roll 6 in contact with the first cooling roll 5 has an elastic surface and is deformed along the surface of the first cooling roll 5 by the pressing force to the first cooling roll 5. A nip is formed between the two. The touch roll 6 is also called a pinching rotary body. As the touch roll 6, a touch roll disclosed in registered patent 3194904, registered patent 3422798, Japanese Patent Application Laid-Open No. 2002-36332, Japanese Patent Application Laid-Open No. 2002-36333, or the like can be preferably used. These can also use what is marketed. These will be described in more detail below.

  FIG. 4 is a cross-sectional view showing an example of the pinching rotator. (The 1st example of touch roll 6 (henceforth, outline section of touch roll A)) is shown. As shown in the drawing, the touch roll A has an elastic roller 42 disposed inside a flexible metal sleeve 41.

  The metal sleeve 41 is made of stainless steel having a thickness of 0.3 mm and has flexibility. If the metal sleeve 41 is too thin, the strength is insufficient, whereas if it is too thick, the elasticity is insufficient.

  For these reasons, the thickness of the metal sleeve 41 is preferably 0.1 to 1.5 mm.

  The elastic roller 42 is formed in a roll shape by providing a rubber 44 on the surface of a metal inner cylinder 43 that is rotatable via a bearing.

  When the touch roll A is pressed toward the first cooling roll 5, the elastic roller 42 presses the metal sleeve 41 against the first cooling roll 5, and the metal sleep 41 and the elastic roller 42 have the shape of the first cooling roll 5. It deforms corresponding to the familiar shape, and forms a nip with the first cooling roll. Cooling water 45 flows in a space formed between the metal sleeve 41 and the elastic roller 42.

  FIG. 5 is a cross-sectional view taken along a plane perpendicular to the rotation axis, showing a second example (hereinafter referred to as touch roll B) of the pinching rotator.

  FIG. 6 is a cross-sectional view showing an example of a plane including the rotation axis of the second example (touch roll B) of the pinching rotator.

  5 and 6, the touch roll B is a flexible and seamless outer tube 51 made of a stainless steel pipe (thickness 4 mm), and a high rigidity arranged in the same axial center inside the outer tube 51. The metal inner cylinder 52 is generally configured.

  A coolant 54 flows in the space 53 between the outer cylinder 51 and the inner cylinder 52. Specifically, in the touch roll B, outer cylinder support flanges 56a and 56b are attached to the rotation shafts 55a and 55b at both ends, and a thin metal outer cylinder 51 is attached between the outer peripheral portions of the both outer cylinder support flanges 56a and 56b. Yes.

  A fluid supply pipe 59 is disposed in the same axial center in a fluid discharge hole 58 formed in the axial center portion of one rotary shaft 55a and forming a fluid return passage 57. The fluid supply pipe 59 is thin-walled. It is connected and fixed to a fluid shaft cylinder 60 arranged at the axial center in the metal outer cylinder 51.

  Inner cylinder support flanges 61a and 61b are attached to both ends of the fluid shaft cylinder 60, respectively, and a thickness of about 15 to 20 mm between the outer periphery of the inner cylinder support flanges 61a and 61b and the other outer cylinder support flange 56b. A metal inner cylinder 52 having a thickness is attached.

  A cooling liquid flow space 53 of, for example, about 10 mm is formed between the metal inner cylinder 52 and the thin metal outer cylinder 51, and the metal inner cylinder 52 has a flow space 53 and an inner space near both ends. An outlet 52a and an inlet 52b are formed to communicate with the intermediate passages 62a and 62b outside the cylinder support flanges 61a and 61b, respectively.

  Further, the outer cylinder 51 is thinned within a range in which the thin cylinder theory of elastic mechanics can be applied in order to have flexibility, flexibility, and resilience close to rubber elasticity.

  The flexibility evaluated by the thin-walled cylinder theory is expressed by the thickness t / roll radius r, and the flexibility increases as t / r decreases.

  In this touch roll B, the flexibility is the optimum condition when t / r ≦ 0.03.

  Usually, the touch roll generally used has a roll diameter R = 200 to 500 mm (roll radius r = R / 2), a roll effective width L = 500 to 1600 mm, and a horizontally long shape with r / L <1. is there.

  As shown in FIG. 6, for example, when the roll diameter R = 300 mm and the roll effective width L = 1200 mm, the appropriate range of the wall thickness t is 150 × 0.03 = 4.5 mm or less, but the molten sheet width is 1300 mm. On the other hand, when the average linear pressure is clamped at 98 N / cm, the equivalent spring constant is equal by setting the wall thickness of the outer cylinder 51 to 3 mm compared to the rubber roll of the same shape. The nip width k in the roll rotation direction of the nip is also about 9 mm, which is almost the same as the nip width of this rubber roll of about 12 mm.

  The deflection amount at the nip width k is about 0.05 to 0.1 mm.

  Here, t / r ≦ 0.03. However, in the case of a general roll diameter R = 200 to 500 mm, flexibility is sufficiently obtained especially in the range of 2 mm ≦ t ≦ 5 mm. Thinning by processing can be easily performed, and it is an extremely practical range. If the wall thickness is 2 mm or less, high-precision processing cannot be performed due to elastic deformation during processing.

  The converted value of 2 mm ≦ t ≦ 5 mm is 0.008 ≦ t / r ≦ 0.05 with respect to a general roll diameter, but in practical use, the roll diameter under the condition of t / r ≦ 0.03. The wall thickness should be increased in proportion to

  For example, when roll diameter: R = 200, t = 2 to 3 mm, and when roll diameter: R = 500, t = 4 to 5 mm.

  The touch rolls A and B are urged toward the first cooling roll by the urging means. The urging force of the urging means is F, and the value F / W (linear pressure) obtained by dividing the width W of the optical film in the nip along the rotation axis of the first cooling roll 5 is 9.8 to 147 N / Set to cm.

  In the present invention, it is preferable that a nip is formed between the touch rolls A and B and the first cooling roll 5 and the flatness is corrected while the optical film passes through the nip. Accordingly, the optical film is sandwiched over a long time with a small linear pressure, compared to the case where the touch roll is formed of a rigid body and no nip is formed between the first cooling roll and the flatness is more reliably corrected. be able to.

  That is, when the linear pressure is smaller than 9.8 N / cm, the die line cannot be sufficiently eliminated. On the other hand, if the linear pressure is greater than 147 N / cm, the optical film is difficult to pass through the nip, resulting in unevenness in place of the thickness of the optical film.

  In addition, since the surfaces of the touch rolls A and B are made of metal, the surfaces of the touch rolls A and B can be made smoother than when the surface of the touch roll is rubber. Can be obtained. In addition, as a material of the elastic body 44 of the elastic roller 42, ethylene propylene rubber, neoprene rubber, silicon rubber, or the like can be used.

  Now, in order to eliminate the die line satisfactorily by the touch roll 6, it is important that the viscosity of the optical film when the touch roll 6 sandwiches the optical film is in an appropriate range.

  Cellulose esters are known to have a relatively large change in viscosity with temperature.

  Therefore, in order to set the viscosity when the touch roll 6 clamps the optical film to an appropriate range, it is important to set the temperature of the optical film when the touch roll 6 clamps the cellulose film to an appropriate range. It becomes.

  When the glass transition temperature of the optical film is Tg, it is preferable to set the temperature T of the optical film immediately before the optical film is sandwiched between the touch rolls 6 so as to satisfy Tg <T <Tg + 110 ° C.

  That is, when the temperature T of the optical film immediately before being sandwiched between the touch rolls 6 is within the above range, the viscosity of the optical film when sandwiching the optical film can be set to an appropriate range, and the die line can be corrected. Further, the surface of the optical film and the roll are uniformly bonded, and the die line can be corrected.

  Tg + 10 ° C. <T <Tg + 90 ° C., more preferably Tg + 20 ° C. <T <Tg + 70 ° C.

  In order to set the temperature of the optical film when the touch roll 6 clamps the optical film to an appropriate range, the first cooling roll is moved from the position where the melt extruded from the casting die 4 contacts the first cooling roll 5. What is necessary is just to adjust the length L along the rotation direction of the 1st cooling roll 5 of the nip of 5 and the touch roll 6. FIG.

  In the present invention, preferred materials for the first roll 5 and the second roll 6 include carbon steel, stainless steel, resin, and the like. The surface accuracy is preferably increased, and the surface roughness is set to 0.3 S or less, more preferably 0.01 S or less.

  In the present invention, by reducing the pressure from the opening (lip) of the casting die 4 to the first roll 5 to 70 kPa or less, the above-described die line correction effect is more greatly manifested. The reduced pressure is preferably 50 to 70 kPa. Although there is no restriction | limiting in particular as a method of keeping the pressure of the part from the opening part (lip | rip) of the casting die 4 to the 1st roll 5 below 70 kPa, Cover the roll periphery from the casting die 4 with a pressure | voltage resistant member, and reduce pressure. There are methods.

  At this time, the suction device is preferably subjected to a treatment such as heating with a heater so that the device itself does not become a place where the sublimate is attached. In the present invention, if the suction pressure is too small, the sublimate cannot be sucked effectively, so it is necessary to set the suction pressure to an appropriate value.

  In the present invention, a film-like cellulose ester in a molten state is transferred from the T die 4 to the first roll (first cooling roll) 5, the second cooling roll 7, and the third cooling roll 8 in order and cooled while being conveyed. Solidify to obtain an unstretched optical film 10.

  In the example of the embodiment of the present invention shown in FIG. 1, the cooled and solidified unstretched optical film 10 peeled from the third cooling roll 8 by the peeling roll 9 is stretched through a dancer roll (optical film tension adjusting roll) 11. The optical film 10 is stretched in the transverse direction (width direction). By this stretching, the molecules in the optical film are oriented.

  As a method for stretching the optical film in the width direction, a known tenter or the like can be preferably used.

  In particular, it is preferable to set the stretching direction to the width direction because lamination with a polarizing film can be performed in a roll form. By stretching in the width direction, the slow axis of the optical film made of cellulose ester is in the width direction.

  On the other hand, the transmission axis of the polarizing film is also usually in the width direction. By incorporating a polarizing plate in which the transmission axis of the polarizing film and the slow axis of the optical film are parallel to each other into the liquid crystal display device, the display contrast of the liquid crystal display device can be increased and a good viewing angle can be obtained. Is obtained.

  The glass transition temperature Tg of the optical film constituting material can be controlled by making the material type constituting the optical film and the ratio of the constituting material different.

  When a retardation film is produced as an optical film, Tg is preferably 120 ° C. or higher, preferably 135 ° C. or higher. In the liquid crystal display device, in the image display state, the temperature environment of the optical film changes due to the temperature rise of the device itself, for example, the temperature rise derived from the light source.

  At this time, if the Tg of the optical film is 120 ° C. or higher than the environmental temperature of the optical film, the retardation value derived from the orientation state of the molecules fixed inside the optical film by stretching and the dimensional shape as the optical film are adjusted. Easy to do.

  When the Tg of the optical film is 250 ° C. or less, the temperature when the optical film constituting material is made into an optical film can be optimized, energy consumption for heating is drastically reduced, and the material itself is decomposed when it is made into an optical film. There is no coloration. Therefore, Tg is preferably 120 ° C to 250 ° C.

  In the stretching step, known heat setting conditions, cooling, and relaxation treatment may be performed, and adjustment may be made as appropriate so as to have characteristics required for the target optical film.

  In order to give the optical film the physical properties of the polarizing plate protective film and the retardation film function for expanding the viewing angle of the liquid crystal display device, the stretching step and the heat setting treatment are appropriately selected and performed. When such a stretching step and heat setting treatment are included, the heating and pressurizing step is performed before the stretching step and heat setting treatment.

  When combining the function of a retardation film and the function of a polarizing plate protective film as an optical film, it is necessary to perform refractive index control. However, the refractive index control can be performed by a stretching operation, and a stretching operation is preferable. Is the method. Hereinafter, the stretching method will be described. Stretching is performed by longitudinal stretching (stretching in the longitudinal direction), lateral stretching (stretching in the width direction), and combinations thereof. Longitudinal stretching includes roll stretching (stretching in the longitudinal direction using two or more pairs of nip rolls with increased peripheral speed on the outlet side) and fixed-end stretching (gripping both ends of the film and transporting it gradually in the longitudinal direction. Stretching in the direction) or the like. In addition, the transverse stretching can be performed by tenter stretching (holding both ends of the film with a chuck and stretching the film in the width direction (perpendicular to the longitudinal direction)) or the like.

  These longitudinal stretching and lateral stretching may be performed independently (uniaxial stretching) or may be performed in combination (biaxial stretching). In the case of biaxial stretching, it may be carried out in the longitudinal and transverse sequential manners (sequential stretching) or simultaneously (simultaneous stretching). The stretching speed of longitudinal stretching and lateral stretching is preferably 10% / min to 10000% / min, more preferably 20% / min to 1000% / min, and further preferably 30% / min to 800% / min. In the case of multistage stretching, the stretching speed refers to the average value of the stretching speed of each stage. Following such stretching, it is also preferable to relax by 0% to 10% in the longitudinal or transverse direction. Furthermore, it is also preferable to heat-fix at 150-250 degreeC for 1 second-3 minutes following extending | stretching.

  The optical film of the present invention can control the required retardation Ro and Rth by stretching 1.1 to 5.0 times in at least one direction. 1.1 to 5.0 times in at least one direction means a ratio after stretching with respect to before stretching obtained by longitudinal stretching, lateral stretching, and a combination thereof.

  By stretching to the above range, widening is facilitated, retardation is adjusted and the flatness of the optical film is improved to a high degree, a horse back failure and a failure called core transfer, and wrinkles when starting to roll the film Occurrence can be remarkably prevented. Further, if the draw ratio exceeds 5.0 times, drawing becomes difficult and film breakage occurs or film thickness unevenness is likely to occur.

  Further, when the film is stretched in the melt casting direction, if the contraction in the width direction is too large, the value of the refractive index in the thickness direction becomes too large. In this case, it can be improved by suppressing the width shrinkage of the film or stretching in the width direction. When stretching in the width direction, the refractive index may be distributed in the width direction. This distribution may appear when the tenter method is used. By stretching the film in the width direction, a shrinkage force is generated at the center of the film, and the phenomenon is caused by the end being fixed. It is thought to be called the Boeing phenomenon. Even in this case, by stretching in the casting direction, the bowing phenomenon can be suppressed and the distribution of the phase difference in the width direction can be reduced.

  By stretching in the biaxial directions perpendicular to each other, the film thickness variation of the obtained film can be reduced. When the film thickness variation of the retardation film is too large, the retardation becomes uneven, and unevenness such as coloring may be a problem when used in a liquid crystal display.

  For the purposes as described above, the method of stretching in the biaxial directions orthogonal to each other is effective, and the stretching ratio in the biaxial directions orthogonal to each other is such that the stretching ratio in one direction is 1.1 to 3.0 times. The other stretch ratio is stretched to 1.0 to 3.0 times, and more preferably the unidirectional stretch ratio is stretched to 1.1 to 2.5 times. A stretched ratio of 1.0 to 2.5 times is preferable, and a stretch ratio in one direction is preferably stretched to 1.1 to 2.0 times, and the other stretch ratio is 1.0 to 2 It has been stretched by a factor of 0. Thereby, while being able to obtain the optical film which has the retardation value of this invention preferably, an optical film with favorable flatness can be obtained.

  When the absorption axis of the polarizer exists in the longitudinal direction, the transmission axis of the polarizer coincides with the width direction. In order to obtain a long polarizing plate, the retardation film is preferably stretched so as to obtain a slow axis in the width direction.

  When a cellulose resin that obtains positive birefringence with respect to stress is used, the slow axis of the retardation film can be imparted in the width direction by stretching in the width direction from the above-described configuration. In this case, in order to improve display quality, it is preferable that the slow axis of the retardation film is in the width direction. In order to obtain a target retardation value, (stretch ratio in the width direction)> (longitudinal) It is preferable to satisfy the condition of the direction stretching ratio). After stretching, after slitting the edge of the film to a product width by the slitter 13, the film is subjected to knurling (embossing) on both ends of the film by a knurling device comprising an embossing ring 14 and a back roll 15. By winding with the winder 16, sticking in the cellulose ester film (original winding) and generation of scratches are prevented. The knurling method can process a metal ring having an uneven pattern on its side surface by heating or pressing. In addition, since the grip part of the clip of the both ends of a film is deform | transforming normally and cannot be used as a film product, it is cut out and reused as a raw material.

  After stretching, the end of the optical film is slit to a product width by the slitter 13 and cut off, and then knurled (embossing) is applied to both ends of the optical film by a knurling device comprising the embossing ring 14 and the back roll 15. Application and winding by the winder 16 prevents sticking in the optical film (original winding) F and generation of scratches. The knurling method can process a metal ring having an uneven pattern on its side surface by heating or pressing. In addition, since the grip part of the clip of the optical film both ends is deform | transforming normally and cannot be used as an optical film product, it is cut out and reused as a raw material.

  Next, the winding process of the optical film is performed by keeping the shortest distance between the outer peripheral surface of the cylindrically wound optical film and the outer peripheral surface of the mobile transport roll immediately before the optical film as a winding roll. It is to be wound up. In addition, a means such as a static elimination blower for removing or reducing the surface potential of the optical film is provided in front of the winding roll.

  The winder related to the production of the optical film of the present invention may be generally used, and it may be a winding method such as a constant tension method, a constant torque method, a taper tension method, or a program tension control method with a constant internal stress. Can be wound up. In addition, it is preferable that the initial winding tension at the time of winding of the optical film is 90.2 to 300.8 N / m.

  In the winding process of the optical film in the method of the present invention, the optical film is preferably wound under environmental conditions of a temperature of 20 to 30 ° C. and a humidity of 20 to 60% RH.

  If the temperature in the winding process is in the range of 20 to 30 ° C., there will be no wrinkles and there will be no deterioration of the optical film winding quality.

  Moreover, if the humidity in the winding process of the optical film is 20 to 60% RH, it is difficult to be charged, the optical film winding quality deterioration is reduced, the winding quality is excellent, there is no sticking failure, and the transportability is not deteriorated. .

  When winding the optical film into a roll, the wound core may be any material as long as it is a cylindrical core, but is preferably a hollow plastic core, and the plastic material is heated. Any heat-resistant plastic that can withstand the processing temperature may be used, and examples thereof include phenol resins, xylene resins, melamine resins, polyester resins, and epoxy resins.

  A thermosetting resin reinforced with a filler such as glass fiber is preferred. For example, a hollow plastic core: a wound core made of FRP having an outer diameter of 6 inches (hereinafter, 1 inch is 2.54 cm) and an inner diameter of 5 inches is used.

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

  The production effect obtained by the present invention is particularly remarkable in a long roll of an optical film having a length of 100 m or more and a width of a film having a width of 1.35 m or more, and the length is 1500 m, 2500 m, and 5000 m. The longer the length, the better the width becomes 2 m and 4 m.

  In the production of the optical film of the present invention, the length of the roll is preferably 10 to 5000 m, more preferably 50 to 4500 m in consideration of productivity and transportability. The width of the optical film at this time can be selected from the width of the polarizing film and the width suitable for the production line, but the optical film has a width of 0.5 to 4.0 m, preferably 0.6 to 3.0 m. From the viewpoint of productivity, it is preferable to manufacture the film in a roll shape.

  In the production of the optical film of the present invention, functional layers such as an antistatic layer, a hard coat layer, a slippery layer, an adhesive layer, an antiglare layer, and a barrier layer may be coated before and / or after stretching. . At this time, various surface treatments such as corona discharge treatment, plasma treatment, and chemical treatment can be performed as necessary.

  In the film forming process, the clip gripping portions at both ends of the cut film are pulverized or granulated as necessary, and then used as a film material of the same product type or as a film material of a different product type. It may be reused.

  An optical film having a laminated structure can be produced by co-extrusion of a composition containing a cellulose resin having different additive concentrations such as the plasticizer, the ultraviolet absorber, and the matting agent. For example, an optical film having a structure of skin layer / core layer / skin layer can be produced. For example, the matting agent can be contained in the skin layer in a large amount or only in the skin layer. The plasticizer and the ultraviolet absorber can be contained in the core layer more than the skin layer, and may be contained only in the core layer. In addition, the type of plasticizer and ultraviolet absorber can be changed between the core layer and the skin layer. For example, the skin layer contains a low-volatile plasticizer and / or an ultraviolet absorber, and the core layer has excellent plasticity. It is also possible to add a plasticizer or an ultraviolet absorber excellent in ultraviolet absorption. The glass transition temperature of the skin layer and the core layer may be different, and the glass transition temperature of the core layer is preferably lower than the glass transition temperature of the skin layer. At this time, the glass transition temperatures of both the skin and the core can be measured, and an average value calculated from these volume fractions can be defined as the glass transition temperature Tg and similarly handled. Also, the viscosity of the melt containing the cellulose ester during melt casting may be different between the skin layer and the core layer, and the viscosity of the skin layer> the viscosity of the core layer or the viscosity of the core layer ≧ the viscosity of the skin layer may be used.

  In general, it is known that the melt-extrusion tends to increase the residence time on the end side due to the shape of the casting die, and this is thought to promote the coloring of the film end. In the present invention, the yellow index Ye at the end in the width direction of the film immediately after melt extrusion and the yellow index Yc at the center of the film preferably satisfy the following formula (4), more preferably Ye / Yc is 3.0 or less. It is. If Ye / Yc is greater than 5.0, the color of the produced film increases when the film edge is cut off and reused as a raw material. In the present invention, the yellow index at the end is defined as the maximum value within 30 mm from both ends in the width direction of the film.

Formula 1.0 ≦ Ye / Yc ≦ 5.0
The dimensional change rate of the optical film of the present invention is preferably within ± 1.0%, more preferably within ± 0.5% in the treatment for 50 hours under high temperature and high humidity of 80 ° C. and 90% RH, More preferably, it is within ± 0.4%, particularly preferably within ± 0.3%.

  When the retardation film is a polarizing plate protective film, the thickness of the protective film is preferably 10 to 500 μm. In particular, the lower limit is 20 μm or more, preferably 30 μm or more. The upper limit is 150 μm or less, preferably 120 μm or less. A particularly preferred range is 25 to 90 μm. If the retardation film is thick, the polarizing plate after polarizing plate processing becomes too thick, so that it is not suitable for the purpose of thin and light in liquid crystal displays used for notebook personal computers and mobile electronic devices. On the other hand, when the retardation film is thin, it is difficult to develop retardation as a retardation film, and in addition, the moisture permeability of the film is increased, and the ability to protect the polarizer from humidity tends to be reduced. The film thickness variation of the optical film of the present invention is preferably ± 3%, more preferably ± 1%.

  When the optical film according to the present invention is used as a retardation film, for example, the configuration shown in FIG. 7 can be taken.

  In FIG. 7, 21a and 21b are protective films, 22a and 22b are retardation films, 25a and 25b are polarizers, 23a and 23b are slow axis directions of the film, 24a and 24b are transmission axis directions of the polarizer, 26a, Reference numeral 26b denotes a polarizing plate, 27 denotes a liquid crystal cell, and 29 denotes a liquid crystal display device.

  The in-plane retardation Ro is observed from the normal direction of the display surface when the two polarizing plates are arranged in crossed Nicols and the liquid crystal cell is arranged between the polarizing plates, for example, in the configuration shown in FIG. When the light is in the crossed Nicol state with respect to the time when the display is taken, the polarizing plate is displaced from the crossed Nicol state when observed obliquely from the normal of the display surface, and light leakage caused by this is mainly compensated. As shown in FIG. 7, the retardation in the thickness direction is a configuration in which two polarizing plates are arranged above and below the liquid crystal cell in the liquid crystal display device. The distribution of Rth can be selected.

(Polarizer)
The polarizing plate of the present invention will be described.

  The polarizing plate can be produced by a general method. The back side of the optical film of the present invention is subjected to alkali saponification treatment, and the treated optical film is bonded 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. The optical film of the present invention may be used on the other surface, or another polarizing plate protective film may be used. With respect to the optical film of the present invention, a commercially available cellulose ester film can be used as the polarizing plate protective film used on the other surface. For example, as a commercially available cellulose ester film, Konica Minoltac KC8UX, KC4UX, KC5UX, KC8UCR3, KC8UCR4, KC8UCR5, KC8UY, KC4UY, KC12UR, KC4FR-1, KC4FR-3, KC4FR-3, KC4FR-3, CC4FR-3, KC4FR-3 KC4UE, KC8UE, KC8UY-HA, KC8UX-RHA, KC8UXW-RHA-C, KC8UXW-RHA-NC, KC4UXW-RHA-NC (manufactured by Konica Minolta Opto Co., Ltd.) and the like are preferably used. Alternatively, it is also preferable to use a polarizing plate protective film that also serves as an optical compensation film having an optical anisotropic layer formed by aligning liquid crystal compounds such as discotic liquid crystal, rod-shaped liquid crystal, and cholesteric liquid crystal. For example, the optically anisotropic layer can be formed by the method described in JP-A-2003-98348. By using in combination with the antireflection film of the present invention, a polarizing plate having excellent flatness and a stable viewing angle expansion effect can be obtained.

  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 one in which iodine is dyed on a system film and one in which dichroic dye is dyed. 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. On the surface of the polarizing film, one side of the optical film of the present invention is bonded to form a polarizing plate. It is preferably bonded with an aqueous adhesive mainly composed of completely saponified polyvinyl alcohol or the like.

  Since the polarizing film is stretched in a uniaxial direction (usually the longitudinal direction), when the polarizing plate is placed in a high-temperature and high-humidity environment, the stretching direction (usually the longitudinal direction) shrinks, and the direction perpendicular to the stretching (usually the width direction) ) Will grow. As the thickness of the polarizing plate protective film becomes thinner, the expansion / contraction ratio of the polarizing plate increases, and in particular, the amount of contraction in the stretching direction of the polarizing film increases. Normally, the stretching direction of the polarizing film is bonded to the casting direction (MD direction) of the polarizing plate protective film. Therefore, when making the polarizing plate protective film thin, it is particularly important to suppress the stretching rate in the casting direction. It is. Since the optical film of the present invention is extremely excellent in dimensional stability, it is suitably used as such a polarizing plate protective film.

  That is, even when the durability test is performed at 60 ° C. and 90% RH, the wavy unevenness does not increase, and even if the polarizing plate has an optical compensation film on the back side, the viewing angle characteristics fluctuate after the durability test. Good visibility can be provided without doing so.

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

  In the polarizing plate of the present invention, a polarizing plate protective film of a cellulose derivative is used on the surface opposite to the retardation film as viewed from the polarizer, and a general-purpose TAC film or the like can be used. The polarizing plate protective film located on the side far from the liquid crystal cell can be provided with another functional layer in order to improve the quality of the display device.

  For example, it may be affixed to a film containing a known functional layer as a constituent for display in order to prevent reflection, anti-glare, scratch resistance, dust adhesion prevention, brightness improvement, or the polarizing plate surface of the present invention. It is not limited to.

  In general, a retardation film is required to obtain stable optical characteristics that the fluctuation of Ro or Rth is small as the retardation value. In particular, in a liquid crystal display device in a birefringence mode, these fluctuations may cause image unevenness.

  Since the retardation film produced by the melt casting film forming method according to the present invention is mainly composed of a cellulose resin, the alkali treatment step can be utilized by utilizing saponification inherent to the cellulose resin. When the resin which comprises a polarizer is polyvinyl alcohol, it can be bonded with the said retardation film using complete saponified polyvinyl alcohol aqueous solution similarly to the conventional polarizing plate protective film. For this reason, this invention is excellent in the point which can apply the conventional polarizing plate processing method, and is excellent especially in the point from which the roll polarizing plate which is elongate is obtained.

  The production effect obtained by the present invention becomes more remarkable particularly in a long roll of 100 m or more, and the longer the length is 1500 m, 2500 m, or 5000 m, the more the production effect of polarizing plate production is obtained.

  For example, in the retardation film production, the roll length is 10 m or more and 5000 m or less, preferably 50 m or more and 4500 m or less in consideration of productivity and transportability. The width of the film at this time is the width of the polarizer or the production. A width suitable for the line can be selected. A film is produced with a width of 0.5 m or more and 4.0 m or less, preferably 0.6 m or more and 3.0 m or less, wound into a roll, and may be used for polarizing plate processing. After a film is manufactured and wound on a roll, the film may be cut to obtain a roll having a desired width, and such a roll may be used for polarizing plate processing.

  The optical film of the present invention can be used for a polarizing plate protective film. When using as a polarizing plate protective film, the manufacturing method of a polarizing plate is not specifically limited, It can manufacture by a general method. The obtained optical film is alkali-treated, and a polarizer protective film is bonded to both sides of the polarizer using a completely saponified polyvinyl alcohol aqueous solution on both sides of the polarizer prepared by immersing and stretching the polyvinyl alcohol film in an iodine solution. There is a method, and an optical film which is a polarizing plate protective film of the present invention is directly bonded to a polarizer on at least one side.

  Instead of the alkali treatment, polarizing plate processing may be performed by performing easy adhesion processing as described in JP-A-6-94915 and JP-A-6-118232.

(Liquid crystal display device)
Of the display devices in which the optical film of the present invention is used, a liquid crystal display device suitably used will be described.

  The polarizing plate including the optical film of the present invention can exhibit high display quality as compared with a normal polarizing plate.

  The polarizing plate of the present invention includes an MVA (Multi-domain Vertical Alignment) mode, a PVA (Patterned Vertical Alignment) mode, an OCB (Optical Compensated InP) mode, an OCB (Optical Compensated InP mode) In particular, the use in the IPS mode is effective.

  The transverse electric field switching mode of the present invention includes a fringe-field switching (FFS) mode in the present invention, and the polarizing plate of the present invention can be incorporated in the same manner as the IPS mode, and has the same effect. The liquid crystal display device of the invention can be manufactured.

  Liquid crystal display devices are being applied as devices for colorization and moving image display, and the display quality is improved by the present invention, and the improvement of contrast and the resistance of polarizing plates improve the display of moving images that are less fatigued and faithful. It becomes possible.

  In a liquid crystal display device including at least a polarizing plate including the retardation film, one polarizing plate including the retardation film is disposed with respect to the liquid crystal cell, or two are disposed on both sides of the liquid crystal cell. At this time, it can contribute to improvement in display quality by using the retardation side of the present invention contained in the polarizing plate so as to face the liquid crystal cell of the liquid crystal display device. In FIG. 7, the films 22a and 22b face the liquid crystal cell of the liquid crystal display device.

  In such a configuration, the retardation film can optically compensate the liquid crystal cell. When the polarizing plate of the present invention is used in a liquid crystal display device, at least one polarizing plate in the liquid crystal display device may be the polarizing plate of the present invention. By using the polarizing plate of the present invention, a liquid crystal display device with improved display quality and excellent viewing angle characteristics can be provided.

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

Example 1
(Preparation of optical film F-1)
Optical film F-1 was produced by the melt casting method using the following additive and cellulose ester.

Cellulose ester C-1: cellulose acetate propionate (acetyl group substitution degree 1.64, propionyl group substitution degree 1.21, weight average molecular weight = 220,000 (polystyrene conversion), dispersity (Mw / Mn) = 3.2 ) 100 parts by mass Polymer of the present invention AMP-1 10 parts by mass IRGANOX-1010 (manufactured by Ciba Japan) 0.5 parts by mass GSY-P101 (manufactured by Sakai Chemical Industry Co., Ltd.) 0.3 parts by mass Sumizer-GS (Sumitomo) 0.3 mass part Tinuvin-928 (manufactured by Ciba Japan) 2.0 mass part Aerosil NAX50 (manufactured by Nippon Aerosil Co., Ltd.) 0.2 mass part KE-P100 (manufactured by Nippon Shokubai Co., Ltd.) 0.02 mass Part The above additives and cellulose ester were mixed and dried under reduced pressure at 60 ° C. for 5 hours. This cellulose ester composition was melt-mixed at 235 ° C. using a twin-screw extruder and pelletized.

  Next, a schematic flow sheet showing one embodiment of an apparatus for carrying out the optical film manufacturing method of the present invention is shown in FIG. 2, and the manufacturing method will be described with reference to FIG.

  The pellets obtained above were dried at 100 ° C. for 4 hours, then heated and melted at 250 ° C. in a nitrogen atmosphere, and then extruded from the T-type casting die 4 onto the first cooling roll 5 for the first cooling A film was sandwiched between the roll 5 and the elastic touch roll 6 to form.

  Thereafter, after passing through the second cooling roll 7 and the third cooling roll 8, it is heated at 165 ° C. and stretched by 1.4 times in the longitudinal direction (MD direction) by roll stretching, followed by a preheating zone, a stretching zone, and holding. After being introduced into a tenter having a zone and a cooling zone (there is also a neutral zone for ensuring heat insulation between the zones), and stretching in the width direction (TD direction) at 165 ° C. by 1.50 times The film was cooled to 70 ° C while relaxing 2% in the width direction, then released from the clip, the clip gripping part was cut off, and both ends of the film were knurled with a width of 10 mm and a height of 5 µm, and a winding tension of 220 N / m And wound around the core with a taper of 40%. At this time, the preheating temperature and the holding temperature were adjusted to prevent the bowing phenomenon due to stretching. An optical film F-1 having a finished film width of 1960 mm, a winding length of 3200 m, and a film thickness of 40 μm was produced.

  The first cooling roll and the second cooling roll were made of stainless steel having a diameter of 40 cm, and the surface was hard chrome plated. Further, oil for temperature adjustment was circulated inside to control the roll surface temperature.

  The elastic touch roll had a diameter of 20 cm, the inner cylinder and the outer cylinder were made of stainless steel, and the surface of the outer cylinder was hard chrome plated. The wall thickness of the outer cylinder was 2 mm, and the surface temperature of the elastic touch roll was controlled by circulating oil for temperature adjustment in the space between the inner cylinder and the outer cylinder.

  The surface temperature of the elastic touch roll was 130 ° C., the surface temperature of the first cooling roll was 130 ° C., and the surface temperature of the second cooling roll was 100 ° C. The surface temperature of each roll of the elastic touch roll, the first cooling roll, and the second cooling roll is determined by measuring the temperature of the roll surface at a position 90 ° before the rotation direction from the position where the film first contacts the roll. The average value obtained by measuring 10 points in the width direction using was used as the surface temperature of each roll.

  As the size of the winding core, an inner diameter of 152 mm, an outer diameter of 180 mm, and a length of 2.1 m were used. As the core material for the core, a prepreg resin in which an epoxy resin was impregnated with glass fiber or carbon resin was used. The surface of the core was coated with an epoxy conductive resin, the surface was polished, and the surface roughness Ra was finished to 0.3 microns.

The glass transition temperature Tg of this film was 136 ° C. (The glass transition temperature of the film extruded from the die was measured by DSC method (in nitrogen, temperature rising temperature 10 ° C./min) using DSC6200 manufactured by Seiko Co., Ltd.)
Similarly, the present invention is the same except that the polymer AMP-1, cellulose ester C-1, and the draw ratio are changed to the compounds and conditions described in Table 2, Table 3, Table 4, and Table 5 below. Optical films F-2 to F-39 and comparative optical films F-40 to F-47 were prepared. In addition, the addition amount of the compound was replaced with the same amount as the compound of F-1.

  When changing the draw ratio, the lip clearance of the T die was changed so that the film thickness of the finished film after drawing was 40 μm.

  A comparative compound having the following composition was used.

  The weight average molecular weight (Mw) and dispersity (Mw / Mn) of the cellulose ester were calculated by gel permeation chromatography (GPC) in the following manner.

  The measurement conditions are as follows.

Solvent: Tetrahydrofuran Device: HLC-8220 (manufactured by Tosoh Corporation)
Column: TSKgel SuperHM-M (manufactured by Tosoh Corporation)
Column temperature: 40 ° C
Sample concentration: 0.1% by mass
Injection volume: 10 μl
Flow rate: 0.6ml / min
Calibration curve: Standard polystyrene: PS-1 (manufactured by Polymer Laboratories) Mw = 2, 560,000 to 580, a calibration curve with 9 samples was used.

<< Evaluation of optical film >>
The samples described above were evaluated as described below. The results are shown in Tables 4 and 5.

(Evaluation of retardation)
Using the automatic birefringence meter KOBRA-21-ADH (manufactured by Oji Scientific Instruments), the obtained optical film was subjected to a refractive index nx, ny, nz at a wavelength of 590 nm in an environment of a temperature of 23 ° C. and a humidity of 55% RH. The retardation (Ro) in the in-plane direction of the film and the retardation (Rth) in the thickness direction were calculated according to the following formula.

Ro = (nx−ny) × d
Rth = {(nx + ny) / 2−nz} × d
(In the formula, the refractive index nx in the slow axis direction in the film plane, the refractive index ny in the fast axis direction, the refractive index nz in the thickness direction, and the film thickness of the film is d (nm)).
(Haze)
It measured using the haze meter (1001DP type | mold, Nippon Denshoku Industries Co., Ltd.) from the obtained optical film according to JISK-6714.

(Starting wrinkles)
An operation of winding the original film on the core was performed, and when wrinkles occurred at the beginning of the winding and it became defective, the original film was removed from the core and the operation of rewinding was performed. The number of defects at this time was counted. This operation was repeated 10 times, the average value was obtained, and the ranking was performed to the following levels.

A: 0 times or more and less than 1 time B: 1 time or more and less than 3 times C: 3 times or more and less than 5 times D: 5 times or more (horse spine failure, core transfer)
The wound optical film original sample was wrapped twice with a polyethylene sheet, and stored for 30 days under the conditions of 28 ° C. and 55% by the storage method shown in FIG. Then, it was taken out of the box, the polyethylene sheet was opened, the fluorescent lamp tube lit on the surface of the original film sample was reflected, and the distortion or fine disturbance was observed, and the horse back failure was ranked to the following level.

A: Fluorescent lamps appear straight B: Fluorescent lamps appear to be bent partially C: Fluorescent lamps appear to appear mottled In addition, the original film sample after storage is rewound, up to how many meters from the core part, The length at which the core transfer in which the dot-shaped deformation of 50 μm or more or the band-shaped deformation in the width direction was clearly visible was measured, and was ranked according to the following levels.

A: Less than 15 m from the core part B: 15-30 m from the core part
C: 30-50m from the core part
D: 50 m or more from the core part

  From the above table, the optical films F-1 to F-39 obtained by the production method of the present invention have low haze and low retardation even when subjected to stretching treatment, horse back failure, core transfer, winding In the beginning, it was confirmed that there were few wrinkles and productivity was excellent.

Example 2
(Preparation of polarizing plate)
A 120 μm-thick long roll polyvinyl alcohol film was immersed in 100 parts by mass of an aqueous solution containing 1 part by mass of iodine and 4 parts by mass of boric acid, and stretched in the transport direction 5 times at 50 ° C. to form a polarizing film. Next, the optical film F-1 that has been subjected to alkali saponification treatment under the following conditions is attached to one surface of the polarizing film as a polarizing plate protective film, and a 5% aqueous solution of a completely saponified polyvinyl alcohol is used as an adhesive. Similarly, KC4UX manufactured by Konica Minolta Opto Co., Ltd., which had been subjected to alkali saponification treatment, was bonded to one surface and dried to prepare polarizing plate P-1. Similarly, polarizing plates P-2 to P-45 were prepared using the optical films F-2 to F-45.

(Alkaline saponification treatment)
Saponification step 2M-NaOH 50 ° C. 90 seconds Water washing step Water 30 ° C. 45 seconds Neutralization step 10% HCl 30 ° C. 45 seconds Water washing step Water 30 ° C. 45 seconds After saponification treatment, water washing, neutralization, water washing are performed in this order. Subsequently, it dried at 80 degreeC.

(Characteristic evaluation as a liquid crystal display device)
A liquid crystal panel was taken out from a liquid crystal display device [Panasonic liquid crystal television VIERA TH-26LX60 manufactured by Matsushita Electric Industrial Co., Ltd.] including an IPS mode liquid crystal cell, and the polarizing plates arranged above and below the liquid crystal cell were removed to produce the above. Each polarizing plate was attached to both surfaces of the liquid crystal cell using an acrylic pressure-sensitive adhesive (thickness 20 μm) so that the slow axis of the polarizer was parallel to the long side of the liquid crystal cell (0 ± 0.2 degrees). In that case, it bonded so that the said optical films F-1 to F-47 might become a liquid crystal cell side, and evaluated the characteristic as a polarizing plate of an optical film. The results are shown in Table 6.

  Since comparative F-44 had a high haze and F-46 was a brittle film, performance evaluation as a polarizing plate preparation and a liquid crystal display device was not performed.

(Visibility evaluation)
Still images and moving images were displayed on a liquid crystal display panel (liquid crystal display device), and they were visually observed, and the visibility was evaluated as follows.

◎: Black appears dark and clear, and no blurring of moving images is observed. ○: Black appears to be crisp and clear, but slight blurring of moving images is observed. △: There is no blackening. Sharpness is slightly low and blurring of moving images is recognized. ×: There are no black spots, low sharpness, and blurring of moving images is worrisome (evaluation of viewing angle)
The viewing angle of the liquid crystal display device was measured using EZ-Contrast 160D manufactured by ELDIM in an environment of 23 ° C. and 55% RH. As the viewing angle, an effective viewing angle was set in an area where the contrast (ratio of white display to black display) was 20 or more.

  All of the liquid crystal display devices P-1 to P-39 of the present invention were confirmed to have a viewing angle of 160 ° or more when measured from an oblique 45 ° direction.

  Subsequently, the polarizing plate was treated at 60 ° and 90% RH for 500 hours, and the measurement was performed in the same manner. Further, the polarizing plate treated at 60 ° and 90% RH for 1000 hours was measured in the same manner, and evaluated according to the following criteria in four stages.

◎: Effective viewing angle does not vary ○: Effective viewing angle varies slightly △: Effective viewing angle becomes narrow ×: Effective viewing angle becomes extremely narrow

  From Table 6, it can be seen that the polarizing plates and the liquid crystal display devices P-1 to P-39 using the optical film of the present invention are IPS mode liquid crystal display devices with less blurring and blurring and high viewing angle stability. .

It is a general | schematic flow sheet which shows one embodiment of the apparatus which enforces the manufacturing method of the optical film (cellulose ester film) which concerns on this invention. It is a principal part expansion flow sheet of the manufacturing apparatus of FIG. 3A is an external view of the main part of the casting die, and FIG. 3B is a cross-sectional view of the main part of the casting die. It is sectional drawing of 1st Embodiment of a pinching rotary body. It is sectional drawing in the plane perpendicular | vertical to the rotating shaft of 2nd Embodiment of a pinching rotary body. It is sectional drawing in the plane containing the rotating shaft of 2nd Embodiment of a pinching rotary body. It is a disassembled perspective view which shows the outline of the block diagram of a liquid crystal display device. It is a figure which shows the state of storage of an optical film (cellulose ester film) original fabric.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Extruder 2 Filter 3 Static mixer 4 Casting die 5 Rotating support body (1st cooling roll)
6 Nipping pressure rotating body (touch roll)
7 Rotating support (second cooling roll)
8 Rotating support (3rd cooling roll)
9 peeling roll 10 film 11 dancer roll 12 stretching device 13 slitter 14 embossing ring 15 back roll 16 winding device 21a, 21b protective film 22a, 22b phase difference film 23a, 23b slow axis direction of film 24a, 24b transmission of polarizer Axial direction 25a, 25b Polarizers 26a, 26b Polarizer 27 Liquid crystal cell 29 Liquid crystal display device 31 Die body 32 Slit 41 Metal sleeve 42 Elastic roller 43 Metal inner cylinder 44 Rubber 45 Cooling water 51 Outer cylinder 52 Inner cylinder 53 Space 54 Coolant 55a, 55b Rotating shaft 56a, 56b Outer cylinder support flange 60 Fluid shaft cylinder 61a, 61b Inner cylinder support flange 62a, 62b Intermediate passage 110 Winding core body 117 Support plate 118 Base 120 Cellulose ester film original fabric

Claims (13)

A composition comprising cellulose ester and the following polymer (I) is melt cast to form a web, and the web is stretched at least 1.1 times to 5.0 times in at least one direction. A method for producing an optical film.
Polymer (I): At least one ethylenically unsaturated monomer having a partial structure represented by the general formula (1), an aromatic group which may have a substituent, or a substituent A polymer obtained by copolymerizing at least one kind of an ethylenically unsaturated monomer containing a good heterocyclic group or an optionally substituted cycloalkyl group.

(In the formula, R ₁ , R ₂ and R ₃ each independently have an aliphatic group which may have a substituent, an aromatic group which may have a substituent, or a substituent. And any two of R ₁ , R ₂ , and R ₃ are bonded to each other, and together with the N atom to which they are bonded, or the N and C atoms An annular structure may be formed.) The polymer (I) is obtained by copolymerizing an ethylenically unsaturated monomer having a partial structure represented by the general formula (1) and at least one monomer represented by the following general formula (2). The method for producing an optical film according to claim 1, wherein the polymer is a polymer obtained.

(Wherein R _{21 to} R ₂₈ represent a hydrogen atom or a substituent. R ₂₁ and R ₂₂ , R ₂₂ and R ₂₃ , R ₂₃ and R ₂₄ , and R ₂₄ and R ₂₅ are bonded to each other to form a ring. May be formed.) The polymer (I) is obtained by copolymerizing an ethylenically unsaturated monomer having a partial structure represented by the general formula (1) and at least one monomer represented by the following general formula (3). The method for producing an optical film according to claim 1, wherein the polymer is a polymer obtained.

_{(Wherein, R 31} and _{R 32, .n 31} that represents a substituent, and _{n 32,} when the sum of the _{.n 31} and _{n 32} is 2 or more represents an integer of 0 to 3, more for _{R 31,} a A plurality of R ₃₂ , or R ₃₁ and R ₃₂ may be bonded to each other to form a ring.) The polymer (I) is obtained by copolymerizing an ethylenically unsaturated monomer having a partial structure represented by the general formula (1) and at least one monomer represented by the following general formula (4). The method for producing an optical film according to claim 1, wherein the polymer is a polymer obtained.

(Wherein R _{43 to} R ₄₅ represent a hydrogen atom or a substituent. R ₄₁ represents an alkylene group. N ₄₁ represents an integer of 0 or 1. R ₄₂ has a substituent. An aromatic ring that may be substituted, a heterocyclic ring that may have a substituent, or a cycloalkyl group that may have a substituent. The polymer (I) is obtained by copolymerizing an ethylenically unsaturated monomer having a partial structure represented by the general formula (1) and at least one monomer represented by the following general formula (5). The method for producing an optical film according to claim 1, wherein the polymer is a polymer obtained.

(In the formula, R ₅₁ and R ₅₂ represent a hydrogen atom or a substituent. X represents —NR ₅₃ — or —O—. R ₅₃ represents a hydrogen atom or a substituent.) The ethylenically unsaturated monomer having a partial structure represented by the general formula (1) is N-vinylpyrrolidone, N-acryloylmorpholine, N-vinylpiperidone, N-vinylcaprolactam or a mixture thereof. The manufacturing method of the optical film of any one of Claims 1-5 to do. The method for producing an optical film according to any one of claims 1 to 5, wherein the ethylenically unsaturated monomer having a partial structure represented by the general formula (1) is N-acryloylmorpholine. The said cellulose ester is a cellulose ester which satisfy | fills the substitution degree of following formula (1)-(3) simultaneously, The manufacturing method of the optical film of any one of Claims 1-7 characterized by the above-mentioned.
2.40 ≦ X + Y ≦ 3.00 Formula (1)
0 ≦ X ≦ 2.40 (2)
0.10 <= Y <= 3.00 ... Formula (3)
(In the formula, X represents the substitution degree of the acetyl group. Y represents the total substitution degree of the acyl group having 3 to 5 carbon atoms.) The optical film manufactured by the manufacturing method of the optical film of any one of Claims 1-8. It is an optical film manufactured with the manufacturing method of the optical film of any one of Claims 1-8, Comprising: In-plane retardation (Ro) 0 <= Ro <= 10nm, Retardation (Rth) of thickness direction ) Satisfies the range of −20 ≦ Rth ≦ 20 nm at the same time. A polarizing plate, wherein the optical film according to claim 9 or 10 is used on at least one surface. A display device comprising the optical film according to claim 9 or 10 or the polarizing plate according to claim 11 on at least one surface of a liquid crystal cell. The display device according to claim 12, wherein the liquid crystal cell is an IPS mode type.

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