JP2009204848A - Optical film, method for producing the same, polarizing plate using optical film, and display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical film used as a protective film for a polarizing plate in a liquid crystal display, which prevents winding property (winding crease) from deteriorating by reducing the friction coefficient of both ends of the film in the width direction, suppresses haze increase, has high transparency and stable optical characteristics, while being free of degradation of winding quality and stable even with the lapse of time in the original wound state, achieving the reduction of thickness and increase in quality of the film, thereby providing a thin, light-weight, high-definition and high-image-quality liquid crystal display. <P>SOLUTION: A film friction coefficient reducing agent is present on the surface of the optical film, the central part of the film in the width direction has a friction coefficient of 0.40-1.00, both ends of the film in the width direction have a friction coefficient of 0.20-0.99, and the film friction coefficient of the central part in the width direction is larger than the film friction coefficient of both ends in the width direction. The following expression is established: film friction coefficient ratio: (end part friction coefficient)/(central part friction coefficient)=0.50-0.99. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention can also be used for various functional films such as a protective film for polarizing plates used for liquid crystal display devices (LCDs, liquid crystal displays), retardation films, viewing angle widening films, and antireflection films used for plasma displays. It is related with the optical film which can be manufactured, its manufacturing method, the polarizing plate using an optical film, and a display apparatus.

  In recent years, liquid crystal display devices have come to be used in televisions and large monitors due to improvements in image quality and high definition technology. In particular, there is a demand for large screens of liquid crystal displays of these liquid crystal display devices. However, it is also strong against materials for liquid crystal display devices, and there is a demand for increasing the size of optical films as members and increasing the width of optical films.

  On the other hand, the thinning of the liquid crystal display and the thinning of the optical film as a member have progressed. With such a wide film and thin film, the load on the film increases when the film is wound. Quality becomes even more disadvantageous. In particular, the wrinkle deterioration is caused by the resistance (friction, blocking) between the wound films at both ends of the film, such as when the film is wound, or when the film is wrinkled over time after winding. Therefore, more stable winding quality is required.

  In the production of such an optical film, as described in the following Patent Document 1 to Patent Document 5, the friction coefficient of the film surface, the surface roughness, etc. are defined, and an attempt to improve the winding quality is as follows. This has been done in the past.

  Patent Document 1 discloses that a coefficient of friction between film contact surfaces at a temperature of 23 ° C. and a humidity of 55% is a, a coefficient of b at a temperature of 23 ° C. and a humidity of 80% is b, and a coefficient of coefficient at a temperature of 23 ° C. and a humidity of 85%. Describes a cellulose ester film having a thickness of 60 μm or less, where 1.0 ≦ b / a ≦ 1.5 and 1.0 ≦ c / a ≦ 5.0. According to Patent Document 1, it is possible to obtain a cellulose ester film that does not cause wrinkles or breakage even when the film thickness is thin.

Patent Document 2 discloses a cellulose ester film having a thickness of 10 to 50 μm, which is measured on one side of the film after being conditioned for 24 hours in an environment of 23 ° C. and a relative humidity of 55% RH, When the coefficient of dynamic friction between the other surfaces is M (55), M (55) ≦ 0.90, and the film was conditioned for 24 hours in an environment of 23 ° C. and a relative humidity of 65% RH. When the coefficient of dynamic friction between one surface and the other surface of the film measured later is M (65),
1.0 ≦ M (65) / M (55) ≦ 1.2
A cellulose ester film is described.

  According to Patent Document 2, the surface physical properties are improved even when the polarizing plate protective film is thinned with the thinning of the liquid crystal display element, and the convex pressing when rolled up in a roll shape is improved. It is possible to obtain a cellulose ester film used for a protective film for a polarizing plate that has few failures, good slipperiness between films, low frequency of sticking between films, and excellent productivity.

  In Patent Document 3, the produced cellulose ester film is allowed to stand for 48 hours in an environmental condition of a temperature of 80 ° C. and a relative humidity of 90% RH, and is subjected to temperature and humidity control treatment. The difference between the refractive index of at least one side of the film and the refractive index of the same side of the film after the cellulose ester film after production was allowed to stand for 48 hours under an environmental condition of a temperature of 23 ° C. and a relative humidity of 55% RH. However, the cellulose ester film which is 0.0080 or less is described.

  According to Patent Document 3, a so-called winding of a cellulose ester film used for a protective film for a polarizing plate accompanying an increase in productivity (increase in production) of a liquid crystal display element used in a liquid crystal display device (LCD), that is, a polarizing plate. Improve quality. In particular, it improves the prevention of sticking failure at the time of winding the film and makes it possible to increase the productivity of the protective film for polarizing plates.

Patent Document 4 is a cellulose ester film containing a matting agent, where the dynamic friction coefficient at a point contact load A is μA, and the dynamic friction coefficient at a surface contact (apparent area 63 × 63 mm ² ) load B is μB.
0.5 ≦ μA ≦ 1.5 and 1.0 ≦ μA / μB ≦ 1.3
A cellulose ester film is described.

  According to Patent Document 4, for a cellulose ester film that is useful as a protective film for a polarizing plate of a liquid crystal display device (LCD) and can improve the winding quality particularly with a wound product of 5000 m or more, for example, a 5000 m roll. A cellulose ester film capable of suppressing deterioration in winding quality can be obtained even with a wound product with a large load such as the above-described increase in winding diameter.

  Patent Document 5 includes a step of forming a cellulose ester film containing a matting agent and a step of detecting a friction coefficient of the cellulose ester film immediately after winding, and in the film forming step, film friction from the detection step. A method for producing a cellulose ester film is described in which the addition amount of the matting agent is adjusted based on the detected value of the coefficient.

According to Patent Document 5, for a cellulose ester film that is useful as a protective film for a polarizing plate of a liquid crystal display device (LCD), and can improve the winding quality particularly with a wound product of 5000 m or more, for example, a 5000 m roll. Even with a wound product with a large load such as the above-described increase in winding diameter, deterioration of winding quality can be suppressed.
JP 2003-96208 A JP 2004-168981 A Japanese Patent Laid-Open No. 2004-175879 JP 2005-298559 A Japanese Patent Laying-Open No. 2005-313467

  However, even with the conventional techniques described in Patent Documents 1 to 5, the effect of improving the winding quality of the film is insufficient. In particular, in the wide film, the failure is more likely to occur with respect to the winding quality. However, there is a problem that improvement cannot be achieved by the conventional technique and similar techniques.

  The object of the present invention is to solve the above-mentioned problems of the prior art, and to reduce the rollability deterioration (winding wrinkles) that deteriorates due to the widening of the film for an optical film used as a protective film for a liquid crystal display element, that is, a polarizing plate. It is improved by lowering the friction coefficient at both ends in the width direction, and furthermore, since the smoothness is improved, there is no need to use a solid fine particle matting agent, which can contribute to a significant reduction in haze. In particular, even when the stretch ratio is increased for widening, the increase in haze is suppressed, and a film with high transparency and stable optical properties can be obtained. Even after the original winding, the winding quality is stable without deterioration, and it can sufficiently meet the demands for optical film thinning, high quality, and optical film quality. Thin lightweight liquid crystal displays, high definition, and further, may play a quality of a liquid crystal display, an optical film, a method of manufacturing the same, is to provide a polarizing plate and a display device using the optical film.

  As a result of intensive studies in view of the above points, the present inventor has improved the winding property deterioration (winding wrinkles) caused by the widening of the optical film by reducing the friction coefficient at both ends in the width direction of the film. I found out that I can do it.

  That is, the deterioration of the winding wrinkles caused by the widening of the optical film is caused by the resistance (friction, blocking) between the wound films at both ends of the film. In other words, when the resistance between the films escapes from the central part toward the end part when the film is wound, the escape at the end part is eliminated and wrinkles occur. Therefore, it has been found that by reducing the coefficient of friction at both ends of the film, the escape tends to occur and the occurrence of a winding wrinkle failure can be suppressed.

  And by improving the smoothness of the film surface, there is no need to use a conventional solid fine particle matting agent, which can contribute to a significant reduction in haze, and further, the stretch ratio is increased to widen the film. In this case, the present inventors have found that a haze increase can be suppressed, a highly transparent film can be obtained, and the above-described conventional problems can be solved, and the present invention has been completed.

In order to achieve the above object, the invention of claim 1 is characterized in that a film friction coefficient reducing agent is present on the film surface, the coefficient of friction at the center in the film width direction is 0.40 to 1.00, and the film width. The friction coefficient at the end in the hand direction is 0.20 to 0.99, the film friction coefficient at the center in the film width direction is larger than the film friction coefficient at the end in the film width direction,
Film friction coefficient ratio: edge friction coefficient / center friction coefficient = 0.50-0.99
It is characterized by being.

  A second aspect of the present invention is the optical film according to the first aspect, wherein the friction coefficient reducing agent is an organopolysiloxane.

  The invention according to claim 3 is the optical film according to claim 1 or 2, wherein the organopolysiloxane has the following general formula (1) or general formula (2). .

General formula (1)
R R ¹
｜ ｜
R-Si- (O-Si-) n-R
｜ ｜
R R
In the formula, R and R ¹ are a methyl group, an ethyl group, an alkyl group having 3 to 14 carbon atoms, a phenyl group, or hydrogen, or at least one hydrogen is fluorine, a polyether group, an amino group, an epoxy group, or a hydroxyl group. A modified methyl group substituted with a carboxyl group, a methacrylate group, an alkoxy group, a modified ethyl group, a modified alkyl group having 3 to 14 carbon atoms, and a modified phenyl group, and R and R ¹ are the same or different. N may be a natural number of 2 to 1000.

General formula (2)
R R ¹ R ²
｜ ｜ ｜
R-Si- (O-Si-) m- (O-Si-) n-R
｜ ｜ ｜
R R R
In the formula, R, R ¹ and R ² are a methyl group, an ethyl group, an alkyl group having 3 to 14 carbon atoms, a phenyl group, or hydrogen, or alternatively at least one hydrogen is fluorine, a polyether group, an amino group, An epoxy group, a hydroxyl group, a carboxyl group, a methacrylate group, a modified methyl group substituted with an alkoxy group, the modified ethyl group, a modified alkyl group having 3 to 14 carbon atoms, and the modified phenyl group, and R ¹ and R ² R and R ¹ , R and R ² may be the same or different, and the sum of the repeating siloxane unit m with R ¹ group and the repeating siloxane unit n with R ² group: m + n = 2 to 1000 is a natural number.

The invention according to claim 4, an optical film according to claim 3, wherein in the general formula (1) or general formula (2), R is a methyl group, R ^1, R ² is a methyl group , Ethyl group, alkyl group having 3 to 14 carbon atoms, phenyl group, or hydrogen, or at least one hydrogen is replaced by fluorine, polyether group, amino group, epoxy group, hydroxyl group, carboxy group, methacrylate group, alkoxy group A modified methyl group, a modified ethyl group, a modified alkyl group having 3 to 14 carbon atoms, and a modified phenyl group, wherein R ¹ and R ² are different substituents.

  The invention of claim 5 is the optical film according to claim 3 or 4, wherein n in the formula of the general formula (1) or m + n in the formula of the general formula (2) is 2 to 500, respectively. It is characterized by being.

  Invention of Claim 6 is an optical film as described in any one of Claims 3-5, Comprising: n in the formula of General formula (1), or m + n in the formula of General formula (2) Is characterized by being 2 to 100 respectively.

  The invention according to claim 7 is the method for producing an optical film according to claim 1 or 2, wherein a resin solution (dope) containing an additive such as a thermoplastic resin and an ultraviolet absorber is used as a metal rotating drum or metal. A method for producing an optical film in which a web is formed by casting on a rotating endless belt (support) made of a film, peeling the web from the support, then stretching the peeled web with a tenter, and winding the film after drying. Applying 0.0001 to 0.03 parts by weight of an organopolysiloxane or a solution thereof as a film friction coefficient reducing agent to 100 parts by weight of a thermoplastic resin on the surface of the transport film before winding, or It is characterized by spraying.

  The invention according to claim 8 is the method for producing an optical film according to claim 1 or 2, wherein a resin solution (dope) containing an additive such as a thermoplastic resin and an ultraviolet absorber is used as a metal rotating drum or metal. A method for producing an optical film in which a web is formed by casting on a rotating endless belt (support) made of a film, peeling the web from the support, then stretching the peeled web with a tenter, and winding the film after drying. The amount of the organopolysiloxane used as the film friction coefficient reducing agent is 0.001 to 0.3 parts by weight as a whole with respect to 100 parts by weight of the thermoplastic resin, and a part of the organopolysiloxane is It is included in the resin solution (dope), and the remainder of the organopolysiloxane or the solution thereof is sprayed on the surface of the transport film before winding by coating or spraying. Since, the ratio of coating or spray amount for doping content of organopolysiloxanes, are characterized by 5-15%.

  Invention of Claim 9 is a manufacturing method of the optical film of Claim 8, Comprising: The ratio of the application | coating or spraying quantity with respect to dope content of organopolysiloxane is 7 to 13%, It is characterized by the above-mentioned. .

  Invention of Claim 10 is a manufacturing method of the optical film of Claim 8 or 9, Comprising: The ratio of application | coating or spraying quantity with respect to dope content of organopolysiloxane is 9 to 11%, It is characterized by the above-mentioned. It is said.

  Invention of Claim 11 is a manufacturing method of the optical film as described in any one of Claims 7-10, Comprising: Organopolysiloxane is following General formula (1) or General formula (2) It is characterized by having.

General formula (1)
R R ¹
｜ ｜
R-Si- (O-Si-) n-R
｜ ｜
R R
In the formula, R and R ¹ are a methyl group, an ethyl group, an alkyl group having 3 to 14 carbon atoms, a phenyl group, or hydrogen, or at least one hydrogen is fluorine, a polyether group, an amino group, an epoxy group, or a hydroxyl group. A modified methyl group substituted with a carboxyl group, a methacrylate group, an alkoxy group, a modified ethyl group, a modified alkyl group having 3 to 14 carbon atoms, and a modified phenyl group, and R and R ¹ are the same or different. N may be a natural number of 2 to 1000.

General formula (2)
R R ¹ R ²
｜ ｜ ｜
R-Si- (O-Si-) m- (O-Si-) n-R
｜ ｜ ｜
R R R
In the formula, R, R ¹ and R ² are a methyl group, an ethyl group, an alkyl group having 3 to 14 carbon atoms, a phenyl group, or hydrogen, or alternatively at least one hydrogen is fluorine, a polyether group, an amino group, An epoxy group, a hydroxyl group, a carboxyl group, a methacrylate group, a modified methyl group substituted with an alkoxy group, the modified ethyl group, a modified alkyl group having 3 to 14 carbon atoms, and the modified phenyl group, and R ¹ and R ² R and R ¹ , R and R ² may be the same or different, and the sum of the repeating siloxane unit m with R ¹ group and the repeating siloxane unit n with R ² group: m + n = 2 to 1000 is a natural number.

The invention of claim 12 is a method of manufacturing an optical film according to claim 11, wherein in the general formula (1) or general formula (2), R is a methyl group, R ^1, R ² is , Methyl group, ethyl group, alkyl group having 3 to 14 carbon atoms, phenyl group, or hydrogen, or at least one hydrogen is fluorine, polyether group, amino group, epoxy group, hydroxyl group, carboxyl group, methacrylate group, alkoxy group A modified methyl group, a modified ethyl group, a modified alkyl group having 3 to 14 carbon atoms, and a modified phenyl group substituted with a group, wherein R ¹ and R ² are different substituents. .

  Invention of Claim 13 is a manufacturing method of the optical film of Claim 11 or 12, Comprising: n in the formula of General formula (1), or m + n in the formula of General formula (2) is 2 respectively. It is characterized by being -500.

  Invention of Claim 14 is a manufacturing method of the optical film as described in any one of Claims 11-13, Comprising: n in the formula of General formula (1), or Formula of General formula (2) The inside m + n is 2-100, respectively.

  The invention of a polarizing plate according to a fifteenth aspect is characterized in that the optical film according to any one of the first to sixth aspects is used on at least one surface.

  The invention of a display device according to claim 16 is characterized in that the polarizing plate according to claim 15 is used.

The invention of the optical film according to claim 1 includes a film friction coefficient reducing agent on the film surface, a friction coefficient of 0.40 to 1.00 at the center of the film width direction, and an end of the film width direction. The friction coefficient is 0.20 to 0.99, and the film friction coefficient at the center in the film width direction is larger than the film friction coefficient at the end in the film width direction.
Film friction coefficient ratio: edge friction coefficient / center friction coefficient = 0.50-0.99
Therefore, according to the invention of the optical film of claim 1, the winding property deterioration (winding wrinkles) that deteriorates due to the widening of the film is improved by reducing the friction coefficient at both ends in the width direction of the film. Furthermore, since the smoothness is improved, it is not necessary to use a solid fine particle matting agent, which can contribute to a significant reduction in haze, and in particular, the stretch ratio is increased for widening. Even in this case, it is possible to obtain a film with high haze suppression, high transparency and stable optical properties, and further stable and stable without deterioration in winding quality even after the original winding of the film. It can fully meet the demands for film thinning, high quality, and optical film quality. As a result, liquid crystal displays are thinner and lighter, higher definition, and higher liquid crystal display quality. An effect that could play a structure forming.

  Invention of Claim 2 is an optical film of Claim 1, Comprising: A friction coefficient reducing agent is organopolysiloxane, According to invention of Claim 2, the width direction both ends of an optical film In order to reduce the friction coefficient of the film, the use of organopolysiloxane improves the smoothness of the film surface. Conventionally, there is no need to use a solid fine particle matting agent, which contributes to a significant reduction in film haze. . In particular, even when the stretch ratio is increased to widen the film, the haze increase is suppressed and a highly transparent film can be obtained.

  Invention of Claim 3 is an optical film of Claim 1 or 2, Comprising: Organopolysiloxane has following General formula (1) or General formula (2).

General formula (1)
R R ¹
｜ ｜
R-Si- (O-Si-) n-R
｜ ｜
R R
In the formula, R and R ¹ are a methyl group, an ethyl group, an alkyl group having 3 to 14 carbon atoms, a phenyl group, or hydrogen, or at least one hydrogen is fluorine, a polyether group, an amino group, an epoxy group, or a hydroxyl group. A modified methyl group substituted with a carboxyl group, a methacrylate group, an alkoxy group, a modified ethyl group, a modified alkyl group having 3 to 14 carbon atoms, and a modified phenyl group, and R and R ¹ are the same or different. N may be a natural number of 2 to 1000.

General formula (2)
R R ¹ R ²
｜ ｜ ｜
R-Si- (O-Si-) m- (O-Si-) n-R
｜ ｜ ｜
R R R
In the formula, R, R ¹ and R ² are a methyl group, an ethyl group, an alkyl group having 3 to 14 carbon atoms, a phenyl group, or hydrogen, or alternatively at least one hydrogen is fluorine, a polyether group, an amino group, An epoxy group, a hydroxyl group, a carboxyl group, a methacrylate group, a modified methyl group substituted with an alkoxy group, the modified ethyl group, a modified alkyl group having 3 to 14 carbon atoms, and the modified phenyl group, and R ¹ and R ² R and R ¹ , R and R ² may be the same or different, and the sum of the repeating siloxane unit m with R ¹ group and the repeating siloxane unit n with R ² group: m + n = 2 to 1000 is a natural number.

  According to invention of Claim 3, in order to reduce the friction coefficient of the both ends of the width direction of an optical film, by using organopolysiloxane which has said General formula (1) or General formula (2), The surface smoothness of the film is improved, and it is not necessary to use a solid fine particle matting agent, which contributes to a significant reduction in the haze of the film. In particular, even when the stretch ratio is increased to widen the film, the haze increase is suppressed and a highly transparent film can be obtained.

The invention according to claim 4, an optical film according to claim 3, wherein in the general formula (1) or general formula (2), R is a methyl group, R ^1, R ² is a methyl group , Ethyl group, alkyl group having 3 to 14 carbon atoms, phenyl group, or hydrogen, or at least one hydrogen is replaced by fluorine, polyether group, amino group, epoxy group, hydroxyl group, carboxy group, methacrylate group, alkoxy group The modified methyl group, the modified ethyl group, the modified alkyl group having 3 to 14 carbon atoms, and the modified phenyl group, wherein R ¹ and R ² are different substituents. According to the present invention, even if the amount of these substituents is small, there is an effect that does not cause winding deterioration such as winding wrinkles or blocking of the film, and when the amount of these substituents increases, larger winding property deterioration occurs. The effect of the stop can be obtained.

  Invention of Claim 5 is an optical film as described in any one of Claim 3 or 4, Comprising: n in the formula of General formula (1), or m + n in the formula of General formula (2) However, according to the invention of claim 5, the rollability deterioration such as film winding wrinkles and blocking is not caused, and the rollability deterioration such as film misalignment failure is caused. There is an effect that there is no.

  5. The optical film according to claim 3, wherein the repeating unit in the general formula (1) of the organopolysiloxane, n, or the repeating unit in the general formula (2), m + n is 2 to 2, respectively. 100 is preferred.

  The invention according to claim 7 is the method for producing an optical film according to claim 1 or 2, wherein a resin solution (dope) containing an additive such as a thermoplastic resin and an ultraviolet absorber is used as a metal rotating drum or metal. A method for producing an optical film in which a web is formed by casting on a rotating endless belt (support) made of a film, peeling the web from the support, then stretching the peeled web with a tenter, and winding the film after drying. Applying 0.0001 to 0.03 parts by weight of an organopolysiloxane or a solution thereof as a film friction coefficient reducing agent to 100 parts by weight of a thermoplastic resin on the surface of the transport film before winding, or According to the invention of claim 7, the winding property deterioration (winding wrinkles) that deteriorates due to the widening of the film is caused by friction at both ends in the width direction of the film. In addition, since the smoothness is improved, there is no need to use a solid fine particle matting agent, which can contribute to a significant reduction in haze, especially for widening. Even when the stretch ratio is high, an increase in haze is suppressed, and an optical film with high transparency and stable optical properties can be produced. In addition, the required level of quality of the optical film can be satisfactorily met, and as a result, the liquid crystal display can be reduced in thickness and weight, increased in definition, and further improved in image quality of the liquid crystal display.

  The invention according to claim 8 is the method for producing an optical film according to claim 1 or 2, wherein a resin solution (dope) containing an additive such as a thermoplastic resin and an ultraviolet absorber is used as a metal rotating drum or metal. A method for producing an optical film in which a web is formed by casting on a rotating endless belt (support) made of a film, peeling the web from the support, then stretching the peeled web with a tenter, and winding the film after drying. The amount of the organopolysiloxane used as the film friction coefficient reducing agent is 0.001 to 0.3 parts by weight as a whole with respect to 100 parts by weight of the thermoplastic resin, and a part of the organopolysiloxane is It is included in the resin solution (dope), and the remainder of the organopolysiloxane or the solution is sprayed on the surface of the transport film before winding by coating or spraying. Therefore, the ratio of the coating or spraying amount to the dope content of the organopolysiloxane is 5 to 15%. According to the invention of claim 8, the winding property deterioration (wrinkle wrinkle) that deteriorates due to the widening of the film. ) By reducing the friction coefficient at both ends in the width direction of the film. Furthermore, since the smoothness is improved, there is no need to use a solid fine particle matting agent, which greatly reduces haze. In particular, even when the stretch ratio is increased for widening, an increase in haze is suppressed, and an optical film having high transparency and stable optical properties can be produced. It is possible to fully meet the demands for optical film thinning, high quality, and optical film quality. As a result, liquid crystal displays are thinner, lighter, higher definition, and more An effect that may play a high quality of the display.

  In the manufacturing method of the optical film of Claim 8, It is preferable that the ratio of the application | coating or spraying quantity with respect to dope content of organopolysiloxane is 7 to 13%, and it is further 9 to 11%. preferable.

  Invention of Claim 11 is a manufacturing method of the optical film as described in any one of Claims 7-10, Comprising: Organopolysiloxane is following General formula (1) or General formula (2) It is what has.

General formula (1)
R R ¹
｜ ｜
R-Si- (O-Si-) n-R
｜ ｜
R R
In the formula, R and R ¹ are a methyl group, an ethyl group, an alkyl group having 3 to 14 carbon atoms, a phenyl group, or hydrogen, or at least one hydrogen is fluorine, a polyether group, an amino group, an epoxy group, or a hydroxyl group. A modified methyl group substituted with a carboxyl group, a methacrylate group, an alkoxy group, a modified ethyl group, a modified alkyl group having 3 to 14 carbon atoms, and a modified phenyl group, and R and R ¹ are the same or different. N may be a natural number of 2 to 1000.

General formula (2)
R R ¹ R ²
｜ ｜ ｜
R-Si- (O-Si-) m- (O-Si-) n-R
｜ ｜ ｜
R R R
In the formula, R, R ¹ and R ² are a methyl group, an ethyl group, an alkyl group having 3 to 14 carbon atoms, a phenyl group, or hydrogen, or alternatively at least one hydrogen is fluorine, a polyether group, an amino group, An epoxy group, a hydroxyl group, a carboxyl group, a methacrylate group, a modified methyl group substituted with an alkoxy group, the modified ethyl group, a modified alkyl group having 3 to 14 carbon atoms, and the modified phenyl group, and R ¹ and R ² R and R ¹ , R and R ² may be the same or different, and the sum of the repeating siloxane unit m with R ¹ group and the repeating siloxane unit n with R ² group: m + n = 2 to 1000 is a natural number.

  According to invention of Claim 11, in order to reduce the friction coefficient of the both ends of the width direction of an optical film, by using organopolysiloxane which has said General formula (1) or General formula (2), The surface smoothness of the film is improved, and it is not necessary to use a solid fine particle matting agent, which contributes to a significant reduction in the haze of the film. In particular, even when the stretch ratio is increased to widen the film, the haze increase is suppressed and a highly transparent film can be obtained.

  In addition, the use of organopolysiloxane produces an effect that the deviation in the width direction of the optical value (in-plane retardation, thickness direction retardation) can be reduced.

The invention of claim 12 is a method of manufacturing an optical film according to claim 11, wherein in the general formula (1) or general formula (2), R is a methyl group, R ^1, R ² is , Methyl group, ethyl group, alkyl group having 3 to 14 carbon atoms, phenyl group, or hydrogen, or at least one hydrogen is fluorine, polyether group, amino group, epoxy group, hydroxyl group, carboxyl group, methacrylate group, alkoxy group A modified methyl group substituted with a group, a modified ethyl group, a modified alkyl group having 3 to 14 carbon atoms, and a modified phenyl group, wherein R ¹ and R ² are different substituents, According to the invention of No. 12, even if the amount of these substituents is small, there is an effect that does not cause winding deterioration such as winding wrinkles and blocking of the film, and when the amount of these substituents increases, Effect of anti Kina winding deterioration is obtained.

  Invention of Claim 13 is a manufacturing method of the optical film of Claim 11 or 12, Comprising: The repeating unit in the formula of General formula (1) of organopolysiloxane, n, or the formula of General formula (2) In the repeating unit, m + n is 2 to 500, respectively. According to the invention of claim 13, without causing deterioration of winding properties such as winding wrinkles and blocking of the film, and failure of winding misalignment of the film, etc. There is an effect that the winding property is not deteriorated.

  In the method for producing an optical film according to any one of claims 11 to 13, the repeating unit in the formula of the general formula (1) of the organopolysiloxane, n, or the repeating unit in the formula of the general formula (2), m + n, It is preferable that it is 2-100 respectively.

  Since the invention of the polarizing plate of claim 15 uses the thin film according to any one of claims 1 to 6 and the optical film with stabilized optical property values on one surface, the invention of claim 15 According to the invention of the polarizing plate, it is possible to sufficiently meet the demands for thinning and high quality polarizing plates using optical films, and the required level of quality of optical films, and consequently thin and light liquid crystal displays. In addition, there is an effect that high definition and further high image quality of the liquid crystal display can be achieved.

  Since the invention of the display device of claim 16 uses the polarizing plate of claim 15, according to the invention of the display device of claim 16, it is excellent in visibility and stable over a long period of time. The display performance can be maintained, and as a result, the liquid crystal display can be reduced in thickness and weight, increased in definition, and further improved in image quality of the liquid crystal display.

  Next, embodiments of the present invention will be described, but the present invention is not limited thereto.

  The optical film according to the present invention can be used for various functional films such as a protective film for a polarizing plate used for a liquid crystal display (LCD), a retardation film, a viewing angle widening film, and an antireflection film used for a plasma display. It can be done.

In the optical film according to the present invention, a film friction coefficient reducing agent is present on the film surface, the friction coefficient at the center in the film width direction is 0.40 to 1.00, and the friction coefficient at the end in the film width direction is 0. .20 to 0.99, and the film friction coefficient at the film width direction center is larger than the film friction coefficient at the film width direction end.
Film friction coefficient ratio: edge friction coefficient / center friction coefficient = 0.50-0.99
It is.

  Here, the friction coefficient of the film surface can be measured according to JIS K 7125.

  In the optical film according to the present invention, in order to reduce the coefficient of friction at both ends in the width direction of the film, if the coefficient of friction at the center of the film is less than 0.40, winding misalignment tends to occur. If the coefficient of friction at the center of the film exceeds 1.00, winding wrinkles and blocking failures are likely to occur. Further, if the friction coefficient at the end in the width direction of the film is less than 0.20, the film is likely to be unwound. If the friction coefficient at the end in the width direction of the film exceeds 0.99, the film tends to wrinkle.

  Further, when the friction coefficient ratio: end friction coefficient / central friction coefficient is less than 0.50, the film is liable to be wound. Moreover, when it exceeds friction coefficient ratio: edge part friction coefficient / center part friction coefficient = 0.99, a winding wrinkle failure will occur easily on a film.

  In the present invention, the film width of the optical film is not limited, but the film width is preferably 1000 mm or more, more preferably 1500 mm or more, and further preferably 1800 mm or more. The film width is preferably 2500 mm or less.

  In this specification, when the film width is 1800 mm or less, the respective one-third portions from both ends of the film width are referred to as film end portions, and the remaining central portions are referred to as film central portions.

  And when a film width exceeds 1800 mm, the part to 600 mm from both ends is called a film edge part among the whole film width, and let the other remaining part be a film center part.

  The friction coefficient reducing agent used in the present invention is preferably an organopolysiloxane.

  Here, the organopolysiloxane has the following general formula (1) or general formula (2).

General formula (1)
R R ¹
｜ ｜
R-Si- (O-Si-) n-R
｜ ｜
R R
In the formula, R and R ¹ are a methyl group, an ethyl group, an alkyl group having 3 to 14 carbon atoms, a phenyl group, or hydrogen, or at least one hydrogen is fluorine, a polyether group, an amino group, an epoxy group, or a hydroxyl group. A modified methyl group substituted with a carboxyl group, a methacrylate group, an alkoxy group, a modified ethyl group, a modified alkyl group having 3 to 14 carbon atoms, and a modified phenyl group, and R and R ¹ are the same or different. N may be a natural number of 2 to 1000.

General formula (2)
R R ¹ R ²
｜ ｜ ｜
R-Si- (O-Si-) m- (O-Si-) n-R
｜ ｜ ｜
R R R
In the formula, R, R ¹ and R ² are a methyl group, an ethyl group, an alkyl group having 3 to 14 carbon atoms, a phenyl group, or hydrogen, or alternatively at least one hydrogen is fluorine, a polyether group, an amino group, An epoxy group, a hydroxyl group, a carboxyl group, a methacrylate group, a modified methyl group substituted with an alkoxy group, the modified ethyl group, a modified alkyl group having 3 to 14 carbon atoms, and the modified phenyl group, and R ¹ and R ² R and R ¹ , R and R ² may be the same or different, and the sum of the repeating siloxane unit m with R ¹ group and the repeating siloxane unit n with R ² group: m + n = 2 to 1000 is a natural number.

In the general formula (1) or the general formula (2), R is a methyl group, and R ¹ and R ² are a methyl group, an ethyl group, an alkyl group having 3 to 14 carbon atoms, a phenyl group, or hydrogen. Or, alternatively, at least one hydrogen is substituted with fluorine, polyether group, amino group, epoxy group, hydroxyl group, carboxyl group, methacrylate group, alkoxy group, modified methyl group, modified ethyl group, or the same number of carbon atoms of 3-14 A modified alkyl group and a modified phenyl group, and R ¹ and R ² are preferably different substituents.

  And n in the formula of the above general formula (1) or m + n in the formula of the general formula (2) is preferably 2 to 500, more preferably 2 to 100, respectively.

  When the repeating unit: n in the formula of the organopolysiloxane of the general formula (1) or the repeating unit: m + n in the formula of the organopolysiloxane of the general formula (2) is less than 2, the film is wrinkled and blocked. This is not preferable because it causes deterioration of winding properties. On the other hand, if the repeating unit: n in the formula of the organopolysiloxane of the general formula (1) or the repeating unit: m + n in the formula of the organopolysiloxane of the general formula (2) exceeds 1000, the film is wound. This is not preferable because it causes winding deterioration such as a shift failure.

  In addition, in the organopolysiloxane compound of the said General formula (2), although the case where the repeating unit of organosiloxane is 2 types is illustrated, the repeating unit of organosiloxane may be 3 or more types.

  For example, when the polymer chain of the organopolysiloxane compound of the general formula (2) further includes a repeating unit of an organosiloxane of the following general formula (3), and the number of repeating units is four, the following results. .

General formula (3)
R ³ R ³
｜ ｜
...-(O-Si-) p- (O-Si-) q -...
｜ ｜
R R
Wherein R, R ¹ , R ² , R ³ , and R ⁴ are a methyl group, an ethyl group, an alkyl group having 3 to 14 carbon atoms, a phenyl group, or hydrogen, or alternatively at least one hydrogen is fluorine, poly An ether group, an amino group, an epoxy group, a hydroxyl group, a carboxyl group, a methacrylate group, a modified methyl group substituted with an alkoxy group, the modified ethyl group, the modified alkyl group having 3 to 14 carbon atoms, and the modified phenyl group. , R ¹ , R ² , R ³ , and R ⁴ are different from each other, and R and R ¹ , R and R ² , R and R ³ , and R and R ⁴ may be the same or different, Sum of repeating siloxane unit m with R ¹ group, repeating siloxane unit n with R ² group, repeating siloxane unit p with R ³ group, and repeating siloxane unit q with R ⁴ group: m + n + p + q is a natural number of 4 to 1000.

  Although explanation is omitted, the same applies to the case where the number of repeating units of organosiloxane is 3 or 5 or more.

  In the method for producing an optical film according to the present invention, a resin solution (dope) containing a thermoplastic resin and an additive such as a plasticizer and an ultraviolet absorber is allowed to flow on a metal rotating drum or a metal rotating endless belt (support). To form a web, peel the web from the support, and then stretch the peeled web with a tenter and wind the film after drying, on the surface of the transport film before winding, An organopolysiloxane or a solution thereof as a film friction coefficient reducing agent of 0.0001 to 0.03 parts by weight with respect to 100 parts by weight of a thermoplastic resin is applied or sprayed by spraying.

  That is, as usual, cellulose ester, plasticizer, ultraviolet absorber and the like are dissolved in an organic solvent to prepare a dope, a film is formed by a solution casting film forming method, and when the film is wound up after completion of drying, Alternatively, the film friction coefficient lowering agent made of organopolysiloxane is made to exist on the film surface by post-processing at at least one point from the end of drying to the start of film winding.

  Post-treatment is a solution in which organopolysiloxane is dissolved in an organic solvent or a soluble solvent such as water, or a low molecular weight liquid organopolysiloxane is applied to the film surface or sprayed by spraying. It is.

  In order to reduce the friction coefficient at both ends in the width direction of the film, a film friction coefficient reducing agent made of organopolysiloxane is present on the film surface, and the friction coefficient at the center in the width direction of the film is the end in the width direction of the film. Post-processing is performed so as to be larger than the film friction coefficient.

  Another method for producing an optical film of the present invention is that a resin solution (dope) containing an additive such as a thermoplastic resin and an ultraviolet absorber is placed on a metal rotating drum or a metal rotating endless belt (support). A method for producing an optical film in which a web is formed by casting, the web is peeled off from a support, the peeled web is then stretched with a tenter, and the film is wound after drying. The total amount of the organopolysiloxane used is 0.001 to 0.3 parts by weight with respect to 100 parts by weight of the thermoplastic resin, and a part of the organopolysiloxane is contained in the resin solution (dope), The remainder of polysiloxane or its solution is sprayed onto the surface of the transport film before winding by coating or spraying. Ratio of coating or spray amount for doping content, are those wherein 5 to 15%.

  Here, the ratio of the coating or spraying amount to the dope content of the organopolysiloxane is preferably 7 to 13%, and more preferably 9 to 11%.

  In this case, in order to make the film friction coefficient reducing agent comprising organopolysiloxane present on the film surface, a part of the organopolysiloxane is contained in the resin solution (dope), and the remainder of the organopolysiloxane or the solution thereof is added. By post-processing, it is applied to the surface of the transport film before winding.

  Post-treatment is a solution in which organopolysiloxane is dissolved in an organic solvent or a soluble solvent such as water, or a low molecular weight liquid organopolysiloxane is applied to the film surface or sprayed by spraying. It is.

  In order to reduce the friction coefficient at both ends in the width direction of the film, a film friction coefficient reducing agent made of organopolysiloxane is present on the film surface, and the friction coefficient at the center in the width direction of the film is the end in the width direction of the film. Post-processing is performed so as to be larger than the film friction coefficient.

  The organopolysiloxane used in the method for producing an optical film of the present invention has the above general formula (1) or general formula (2). Specific examples of these will be described later.

  The optical film of the present invention is produced by a solution casting method, and will be described in detail below.

  In the optical film of the present invention, various resins can be used as the film material.

  In the present invention, the resin preferably used includes, for example, cellulose ester resins having an acyl group substitution degree of 1.8 to 2.80, such as cellulose acetate, cellulose triacetate, cellulose acetate propionate, and cellulose acetate butyrate. Cellulose ether resins, cycloolefin resins, norbornene resins, polycarbonate resins, and polymers of alkylene dicarboxylic acids and diamines having an alkyl group substitution degree of 2.0 to 2.80, such as cellulose methyl ether, cellulose ethyl ether, and cellulose propyl ether Polyamide resins, alkylene dicarboxylic acid and diol polymer, alkylene diol and dicarboxylic acid polymer, cyclohexane dicarboxylic acid and diol polymer, Polyester resin such as polymer of dicarboxylic acid and polymer of aromatic dicarboxylic acid and diol, vinyl acetate resin such as polyvinyl acetate and vinyl acetate copolymer, and polyvinyl acetal resin such as polyvinyl acetal and polyvinyl butyral , Epoxy resins, ketone resins, polyurethane resins such as linear polymers of alkylene diisocyanate and alkylene diol, and the like, and preferably contains at least one selected from these.

  Among these, cellulose ester resins such as cellulose acetate, cellulose acetate propionate, and cellulose acetate butyrate, cycloolefin resins, norbornene resins, and polycarbonate resins are particularly preferable. In addition, two or more compatible polymers may be blended and dope dissolution described later may be performed, but the present invention is not limited to these.

  Examples of the other resin preferably used in the present invention include a homopolymer or a copolymer having an ethylenically unsaturated monomer unit. More preferably, poly (methyl acrylate), poly (ethyl acrylate), poly (propyl acrylate), poly (cyclohexyl acrylate), copolymers of alkyl acrylate, poly (methyl methacrylate), poly (ethyl methacrylate), poly (cyclohexyl methacrylate), alkyl methacrylate (s). Examples include homopolymers or copolymers of acrylic acid or methacrylic acid esters such as ester copolymers. Furthermore, since acrylic acid or methacrylic acid esters are excellent in transparency and compatibility, homopolymers or copolymers having acrylic acid ester or methacrylic acid ester units, particularly homopolymers having acrylic acid or methyl methacrylate units. Polymers or copolymers are preferred. Specifically, polymethyl methacrylate is preferable. Preferred are alicyclic alkyl esters of acrylic acid or methacrylic acid such as polyacrylic acid or polymethacrylic acid cyclohexane, which have advantages such as high heat resistance, low hygroscopicity, and low birefringence. .

  Hereinafter, the present invention will be described by taking cellulose ester as an example.

  In the present invention, a cellulose ester solution containing a cellulose ester and an organic solvent is referred to as a dope, which is used for solution casting to form a cellulose ester film.

  A cellulose ester is a cellulose ester in which a hydroxyl group derived from cellulose is substituted with an acyl group or the like. Examples thereof include cellulose acylates such as cellulose acetate, cellulose triacetate, cellulose acetate propionate, cellulose acetate butyrate and cellulose acetate propionate butyrate, and cellulose acetate having an aliphatic polyester graft side chain. Among these, cellulose acetate, cellulose acetate propionate, and cellulose acetate having an aliphatic polyester graft side chain are preferable. Other substituents may be included as long as the effects of the present invention are not impaired.

  As an example of cellulose triacetate, the substitution degree of acetyl groups is preferably 2.0 or more and 3.0 or less. By setting the degree of substitution within this range, good moldability can be obtained, and desired in-plane retardation (Ro) and thickness direction retardation (Rt) can be obtained. If the substitution degree of the acetyl group is lower than this range, the heat resistance as a retardation film, particularly the dimensional stability under wet heat may be inferior, and if the substitution degree is too large, the necessary retardation characteristics will not be exhibited. There is a case.

  The cellulose used as a raw material for the cellulose ester used in the present invention is not particularly limited, and examples thereof include cotton linter, wood pulp, and kenaf. Moreover, the cellulose ester obtained from them can be mixed and used in arbitrary ratios, respectively.

  In the present invention, the number average molecular weight of the cellulose ester is preferably in the range of 60000 to 300000, since the mechanical strength of the resulting film is strong. Furthermore, 70000-200000 are preferable.

  In the present invention, various additives can be added to the cellulose ester.

  The solvent of the cellulose ester is not particularly limited as long as it is a solvent that can dissolve the cellulose ester, but even a solvent that cannot be dissolved alone can be used if it can be dissolved by mixing with other solvents. Can do. In general, a mixed solvent composed of a good solvent, methylene chloride and a poor solvent of cellulose ester, is used, and the mixed solvent preferably contains 4 to 30% by weight of the poor solvent.

  In addition, examples of good solvents that can be used include methylene chloride, methyl acetate, ethyl acetate, amyl acetate, acetone, tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, cyclohexanone, ethyl formate, 2,2,2- Trifluoroethanol, 2,2,3,3-tetrafluoro-1-propanol, 1,3-difluoro-2-propanol, 1,1,1,3,3,3-hexafluoro-2-methyl-2- Examples include propanol, 1,1,1,3,3,3-hexafluoro-2-propanol, 2,2,3,3,3-pentafluoro-1-propanol, nitroethane, and the like, such as methylene chloride. Of organic halogen compounds, dioxolane derivatives, methyl acetate, ethyl acetate, acetone and the like are preferred organic solvents (ie Mentioned as good solvent). The use of methyl acetate is particularly preferred because the resulting film has less curl.

  Examples of the poor solvent for cellulose ester include alcohols having 1 to 8 carbon atoms such as methanol, ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol, tert-butanol, methyl ethyl ketone, methyl isobutyl ketone, and acetic acid. Examples thereof include ethyl, propyl acetate, monochlorobenzene, benzene, cyclohexane, tetrahydrofuran, methyl cellosolve, and ethylene glycol monomethyl ether. These poor solvents can be used alone or in combination of two or more.

  The optical film of the present invention may contain a plasticizer, an ultraviolet absorber, and a matting agent.

  As the plasticizer, conventionally known plasticizers for cellulose esters can be preferably used. In particular, those having excellent compatibility are preferred, and for example, phosphate esters and carboxylic acid esters are preferred. Examples of phosphate esters include triphenyl phosphate, tricresyl phosphate, phenyl diphenyl phosphate, and the like. Examples of carboxylic acid esters include phthalic acid esters and citric acid esters. Examples of phthalic acid esters include dimethyl phthalate, diethyl phthalate, dioctyl phthalate, and diethyl hexyl phthalate. Mention may be made of tributyl. In addition, butyl oleate, methylacetyl ricinoleate, dibutyl sebacate, triacetin, and the like are also included. Alkylphthalylalkyl glycolates are also preferably used for this purpose. The alkyl in the alkylphthalylalkyl glycolate is an alkyl group having 1 to 8 carbon atoms. Examples of alkyl phthalyl alkyl glycolates include methyl phthalyl methyl glycolate, ethyl phthalyl ethyl glycolate, propyl phthalyl propyl glycolate, butyl phthalyl butyl glycolate, octyl phthalyl octyl glycolate, methyl phthalyl ethyl glycolate, Ethyl phthalyl methyl glycolate, ethyl phthalyl propyl glycolate, propyl phthalyl ethyl glycolate, methyl phthalyl propyl glycolate, methyl phthalyl butyl glycolate, ethyl phthalyl butyl glycolate, butyl phthalyl methyl glycolate, butyl Phthalyl ethyl glycolate, propyl phthalyl butyl glycolate, butyl phthalyl propyl glycolate, methyl phthalyl octyl glycolate, ethyl phthalyl octyl Collate, octyl phthalyl methyl glycolate, octyl phthalyl ethyl glycolate and the like can be mentioned, such as methyl phthalyl methyl glycolate, ethyl phthalyl ethyl glycolate, propyl phthalyl propyl glycolate, butyl phthalyl butyl glycolate, Octyl phthalyl octyl glycolate is preferable, and ethyl phthalyl ethyl glycolate is particularly preferably used. A plasticizer having a large molecular weight is preferable because it can suppress volatilization during extrusion. Examples of these include aliphatic polyesters composed of glycol and dibasic acids such as polyethylene adipate, polybutylene adipate, polyethylene succinate and polybutylene succinate, and fats composed of oxycarboxylic acids such as polylactic acid and polyglycolic acid. Aliphatic polyesters composed of lactones such as aromatic polyesters, polycaprolactone, polypropiolactone and polyvalerolactone, and vinyl polymers such as polyvinylpyrrolidone. These plasticizers can be used alone or in combination.

  It is preferable to contain 1-30 weight% of content of the plasticizer mentioned above with respect to a cellulose ester. By containing the plasticizer in this range, the dimensional stability of the cellulose ester film under wet heat can be improved.

  Examples of ultraviolet absorbers that can be used in the present invention include oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, nickel complex compounds, and the like. A benzotriazole-based compound with little coloring is preferable. Further, ultraviolet absorbers described in JP-A-10-182621 and JP-A-8-337574, and polymer ultraviolet absorbers described in JP-A-6-148430 are also preferably used. As an ultraviolet absorber, from the viewpoint of preventing the deterioration of polarizers and liquid crystals, it is excellent in the ability to absorb ultraviolet rays having a wavelength of 370 nm or less, and from the viewpoint of liquid crystal display properties, the absorption of visible light having a wavelength of 400 nm or more is small. Is preferred.

  Specific examples of UV absorbers useful in the present invention include 2- (2'-hydroxy-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5'-di-tert-butylphenyl) ) Benzotriazole, 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-3'- ert-butyl-5'-methylphenyl) -5-chlorobenzotriazole, 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-2H-benzotriazol-2-yl) phenyl] propionate and the like can be mentioned, but not limited thereto. As commercially available products, TINUVIN 109, TINUVIN 171 and TINUVIN 326 (all manufactured by Ciba Specialty Chemicals) can be preferably used.

  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 is not limited thereto.

  The blending amount of these ultraviolet absorbers is preferably in the range of 0.01 to 10% by weight, more preferably 0.1 to 5% by weight, based on the cellulose ester. If the amount used is too small, the UV absorption effect may be insufficient, and if it is too large, the transparency of the film may be deteriorated. The ultraviolet absorber is preferably one having high heat stability.

  Next, in the optical film of the present invention, organopolysiloxane is used in order to reduce the friction coefficient at both ends in the width direction of the film surface.

  As the organopolysiloxane, those having the following general formula (1) or general formula (2) and the like can be used.

General formula (1)
R R ¹
｜ ｜
R-Si- (O-Si-) n-R
｜ ｜
R R
In the formula, R and R ¹ are a methyl group, an ethyl group, an alkyl group having 3 to 14 carbon atoms, a phenyl group, or hydrogen, or at least one hydrogen is fluorine, a polyether group, an amino group, an epoxy group, or a hydroxyl group. A modified methyl group substituted with a carboxyl group, a methacrylate group, an alkoxy group, a modified ethyl group, a modified alkyl group having 3 to 14 carbon atoms, and a modified phenyl group, and R and R ¹ are the same or different. N may be a natural number of 2 to 1000.

General formula (2)
R R ¹ R ²
｜ ｜ ｜
R-Si- (O-Si-) m- (O-Si-) n-R
｜ ｜ ｜
R R R
In the formula, R, R ¹ and R ² are a methyl group, an ethyl group, an alkyl group having 3 to 14 carbon atoms, a phenyl group, or hydrogen, or alternatively at least one hydrogen is fluorine, a polyether group, an amino group, An epoxy group, a hydroxyl group, a carboxyl group, a methacrylate group, a modified methyl group substituted with an alkoxy group, the modified ethyl group, a modified alkyl group having 3 to 14 carbon atoms, and the modified phenyl group, and R ¹ and R ² R and R ¹ , R and R ² may be the same or different, and the sum of the repeating siloxane unit m with R ¹ group and the repeating siloxane unit n with R ² group: m + n = 2 to 1000 is a natural number.

In the general formula (1) or the general formula (2), R is a methyl group, and R ¹ and R ² are a methyl group, an ethyl group, an alkyl group having 3 to 14 carbon atoms, a phenyl group, or hydrogen. Or, alternatively, at least one hydrogen is substituted with fluorine, polyether group, amino group, epoxy group, hydroxyl group, carboxyl group, methacrylate group, alkoxy group, modified methyl group, modified ethyl group, or the same number of carbon atoms of 3-14 A modified alkyl group and a modified phenyl group, and R ¹ and R ² are preferably different substituents.

  And n in the formula of the above general formula (1) or m + n in the formula of the general formula (2) is preferably 2 to 500, more preferably 2 to 100, respectively.

  The organopolysiloxane used in the present invention will be described.

The organopolysiloxane used in the present invention is formed of an organopolysiloxane skeleton, and includes those having a structural unit represented by the following general formula (S1).

Here, R ₁ and R ₂ may be substituted with a hydrogen atom, an alkyl group, an aryl group, an alkyl group, or an aryl group, and R ₁ and R ₂ may be the same or different. May be. Examples of the alkyl group represented by R ₁ and R ₂ include a methyl group, an ethyl group, and a propyl group. Examples of the aryl group include a phenyl group. Preferred groups for R ₁ and R ₂ are a methyl group and a phenyl group, and a particularly preferred group is a methyl group.

Further, the organopolysiloxane used in the present invention preferably has an end group represented by the following general formula (S2) at both ends.

Here, R ₃ , R ₄ , and R ₅ each represent a hydrogen atom, an alkyl group, or an aryl group, and the alkyl group and aryl may be substituted with a substituent, or R ₃ , R _4, and R ₅ May be the same or different. Examples of the alkyl group represented by R ₃ , R ₄ , and R ₅ include a methyl group and an ethyl group, and examples of the aryl group include a phenyl group. The alkyl group represented by R ₃ , R ₄ and R ₅ includes those substituted with a single or plural aryl groups (for example, a phenyl group, etc.), etc., and R ₃ , R ₄ and R ₅ The aryl group represented also includes those substituted with a single alkyl group or a plurality of alkyl groups (such as a methyl group). Preferred groups for R ₃ , R ₄ and R ₅ are an alkyl group and an aryl group, and a methyl group is particularly preferred.

The organopolysiloxane used in the present invention which is preferably used preferably has an end group represented by the following general formula (I) at both ends.

Here, R ₃ , R ₄ , and R ₅ each represent a hydrogen atom, an alkyl group, or an aryl group, and R ₃ , R ₄ , and R ₅ may be the same or different. Examples of the alkyl group represented by R ₃ , R ₄ , and R ₅ include a methyl group and an ethyl group, and examples of the aryl group include a phenyl group. The alkyl groups represented by R ₃ , R ₄ , and R ₅ include those substituted with a single or plural aryl groups (for example, a phenyl group) and the like, and R ₃ , R ₄ , and R ₅ The aryl group represented by the formula includes those substituted with a single alkyl group or a plurality of alkyl groups (for example, a methyl group). Preferred groups for R ₃ , R ₄ and R ₅ are an alkyl group and an aryl group, and a methyl group is particularly preferred.

Moreover, the organopolysiloxane used in the present invention which is preferably used may have a structural unit represented by the following general formula (II).

Here, R ₆ and R ₇ each represent a hydrogen atom, an alkyl group, or an aryl group, and R ₆ and R ₇ may be the same or different.

As the alkyl group represented by R ₆ and R ₇ , an alkyl group having 1 to 12 carbon atoms is preferable, and examples thereof include a methyl group, an ethyl group, a propyl group, and a butyl group. Examples of the aryl group include a phenyl group and the like. Is mentioned. The alkyl group represented by R ₆ and R ₇ includes those substituted with a single or a plurality of aryl groups (for example, a phenyl group, etc.), and the aryl group represented by R ₆ and R ₇ is Preferred groups of R ₆ and R ₇ , including those substituted with a single or plural alkyl groups (for example, a methyl group, etc.) are a methyl group or a phenyl group.

Although the typical example of the organopolysiloxane used for this invention below is shown, this invention is not limited to these.

  The organopolysiloxane used in the present invention is prepared, for example, by EG Rocault (by EG Rochou) "Chemistry of the Silicone (Chapman & Hall 1951 Edition)" pages 66-70. "Processing and Application of Silicone" (Kansai Plastics Technology Society, 1954), p. 26, FG A Stone (FG, A, Stone) and BG Graham (WAG) Graham) “In Organic Polymers” (Academic Press 1962), pages 230 to 231 and 288 to 295, etc., as well as Japanese Patent Publication Nos. 35-10771 and 43-28694, 45. Of olefins to siloxanes containing SiH by a metal catalyst as shown in Japanese Patent No. 14898 The method according pressurized reaction or can be synthesized by applying the method and the like by co-hydrolysis of the components organosilane fluoroalkyl silanes such as shown in JP-B-36-22361. Some of the organopolysiloxanes used in the present invention are Petrarch Systems. Ins, domestic Shin-Etsu Chemical Co., Ltd., Toray Dow Corning Silicone Co., Ltd., Toshiba. It is also commercially available from Silicone Co., Ltd. and can be easily obtained.

  The viscosity of the organopolysiloxane used in the present invention is preferably about 10 to 100,000 centistokes measured at 25 ° C. with a rotational viscometer.

  In order for the organopolysiloxane used in the present invention to be present on the surface of an optical film, the organopolysiloxane is dissolved in an organic solvent together with a resin such as cellulose ester, a plasticizer, and an ultraviolet absorber, and a film is formed. It can be contained in the film and exist on the surface of the optical film.

  In addition, when the film is formed by the solution casting film forming method and the film is wound up after the drying is completed, or after the drying, the film is post-treated in at least one place between the completion of the drying and the start of the film winding. And it is made to exist on the film surface.

  In this case, there are a method of adding in advance to the coating solution and a method of overcoating or infiltrating the organopolysiloxane itself used in the present invention, but the former is preferable in terms of production cost.

  The refractive index of the organopolysiloxane used in the present invention is not particularly limited, but it is usually suitable that the measured value at 25 ° C. is about 1.385 or more and 1.665 or less, preferably the measured value at 25 ° C. Those in the range of 1.420 to 1.540 are effective. If a refractive index smaller than 1.385 or larger than 1.485 is used, it may affect the transparency of the applied film.

  In the present invention, the rollability deterioration (winding wrinkles) that deteriorates due to the widening of the optical film is improved by reducing the coefficient of friction at both ends in the width direction of the film.

  In particular, the wrinkle deterioration caused by the widening of the optical film is caused by resistance (friction, blocking) between the wound films at both ends of the film. In other words, when the resistance between the films escapes from the central part toward the end part when the film is wound, the escape at the end part is eliminated and wrinkles occur. Therefore, by reducing the coefficient of friction at both ends of the film, the escape is likely to occur, and the occurrence of a winding wrinkle failure can be suppressed.

  According to the optical film of the present invention, in particular, a wide film having a film width of 1500 mm or more, a thin film such as 40 μm, 60 μm, etc. are not deteriorated in winding property, and further, even after the original winding, there is no deterioration in winding quality and is stable. .

  And according to the optical film of this invention, since the smoothness of the film is improving, it is not necessary to use the matting agent of a solid fine particle conventionally, and it contributes to the significant reduction of a haze. In particular, even when the stretch ratio is increased to widen the film, the haze increase is suppressed and a highly transparent film can be obtained.

  Thus, according to the optical film of the present invention, the present invention has been achieved as an unexpected effect when the organopolysiloxane is applied.

  Next, in the optical film of the present invention, for example, when cellulose ester is used as the resin base material, the heat resistance may be lowered if the substitution degree of the acetyl group of the cellulose ester is low. In this case, it is effective to add an antioxidant.

  As the antioxidant, a hindered phenol compound is preferably used, and 2,6-di-t-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di-t-butyl- 4-hydroxyphenyl) propionate], triethylene glycol-bis [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol-bis [3- (3,5 -Di-t-butyl-4-hydroxyphenyl) propionate], 2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-t-butylanilino) -1,3,5 -Triazine, 2,2-thio-diethylenebis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], octadecyl-3- (3 -Di-t-butyl-4-hydroxyphenyl) propionate, N, N'-hexamethylenebis (3,5-di-t-butyl-4-hydroxy-hydrocinnamamide), 1,3,5-trimethyl -2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, tris- (3,5-di-t-butyl-4-hydroxybenzyl) -isocyanurate, etc. Can be mentioned. In particular, 2,6-di-t-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate] is preferred. Further, for example, hydrazine-based metal deactivators such as N, N′-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyl] hydrazine and tris (2,4-di-t -A phosphorus processing stabilizer such as -butylphenyl) phosphite may be used in combination.

  In order to impart slipperiness to the cellulose derivative in the present invention, it is preferable to add fine particles such as a matting agent. Examples of the fine particles include fine particles of an inorganic compound or fine particles of an organic compound.

  Examples of the fine particles of the inorganic compound include fine particles of silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, tin oxide and the like. Of these, fine particles of a compound containing a silicon atom are preferred, and fine silicon dioxide particles are particularly preferred. Examples of the silicon dioxide fine particles include AEROSIL-200, 200V, 300, R972, R972V, R974, R202, R812, R805, OX50, and TT600 manufactured by Aerosil Co., Ltd.

  Examples of the organic compound fine particles include fine particles such as acrylic resin, silicone resin, fluorine compound resin, and urethane resin.

  The primary particle size of the fine particles is not particularly limited, but the average particle size in the film is preferably about 0.05 to 5.0 μm. More preferably, it is 0.1-1.0 micrometer.

  When the cellulose ester film is observed with an electron microscope or an optical microscope, the average particle diameter of the fine particles indicates an average value of the lengths in the major axis direction of the particles at the observation position of the film. As long as the particles are observed in the film, they may be primary particles or secondary particles in which the primary particles are aggregated, but most of the particles that are usually observed are secondary particles.

As an example of the measurement method, 10 vertical cross-sectional photographs are taken at random for each film, and the number of particles in 100 μm ² whose major axis length is in the range of 0.05 to 5 μm for each cross-sectional photograph. Count. The average value of the major axis lengths of the particles counted at this time is obtained, and a value obtained by averaging the average values of 10 locations is defined as the average particle size.

  In the case of fine particles, the primary particle size, the particle size after being dispersed in a solvent, and the particle size added to the film often change, and it is important that the fine particles are finally combined with the cellulose ester in the film. It is to control the particle size formed by aggregation.

  When the average particle diameter of the fine particles exceeds 5 μm, haze deterioration or the like may be observed, or it may cause a failure in a wound state as a foreign matter. Moreover, when the average particle diameter of fine particles is less than 0.05 μm, it becomes difficult to impart slipperiness to the film.

  The fine particles are used by adding 0.04 to 0.5% by weight to the cellulose ester. Preferably, 0.05 to 0.3% by weight, more preferably 0.05 to 0.25% by weight is added. When the amount of fine particles added is 0.04% by weight or less, the film surface roughness becomes too smooth and blocking occurs due to an increase in the friction coefficient. If the amount of fine particles added exceeds 0.5% by weight, the coefficient of friction on the film surface will be too low, causing winding misalignment during winding, and the transparency of the film will be low and haze will be high. The above range is essential because it has no value as a film.

  For the dispersion of the fine particles, it is preferable to treat the composition in which the fine particles and the solvent are mixed with a high-pressure dispersion apparatus. The high-pressure dispersion apparatus used in the present invention is an apparatus that creates special conditions such as high shear and high pressure by passing a composition in which fine particles and a solvent are mixed at high speed through a narrow tube.

It is preferable that the maximum pressure condition inside the apparatus is 980 N / cm ² or more in a thin tube having a tube diameter of 1 to 2000 μm, for example, by processing with a high-pressure dispersion apparatus. More preferably, the maximum pressure condition inside the apparatus is 1960 N / cm ² or more. Further, at that time, those having a maximum reaching speed of 100 m / sec or more and those having a heat transfer speed of 100 kcal / hr or more are preferable.

  Examples of the high-pressure dispersing apparatus as described above include an ultra-high pressure homogenizer (trade name: Microfluidizer) manufactured by Microfluidics Corporation or a nanomizer manufactured by Nanomizer, and other examples include a Manton Gorin type high-pressure dispersing apparatus such as Izumi Food Machinery. Examples thereof include a homogenizer.

  The method for producing an optical film according to the present invention comprises a step of preparing a dope (resin solution) containing a resin such as cellulose ester and various additives, and the dope is made of a metal rotating drum or a metal rotating endless belt (support). Casting up and forming a web, a stretching step of stretching the web peeled from the support by a tenter device, a drying step of drying the web after stretching, and winding up the dried film It has a taking process.

  In the method for producing an optical film according to the present invention, taking the case where the polymer film is a cellulose ester film as an example, the dissolution of the cellulose ester is first performed by a stirring dissolution method, a heating dissolution method, an ultrasonic dissolution in a dissolution vessel. A method such as a method is usually used, and a method of heating under stirring at a temperature not lower than the boiling point of the solvent at a normal pressure and in a range where the solvent does not boil, and dissolving with stirring is not a lump that is called a gel or mamako. In order to prevent generation | occurrence | production of a melt, it is more preferable. Further, a cooling dissolution method described in JP-A-9-95538 or a method of dissolving under high pressure described in JP-A-11-21379 may be used.

  A method in which the cellulose ester is mixed with a poor solvent and wetted or swollen, and then mixed with a good solvent and dissolved is also preferably used. At this time, an apparatus for mixing or dissolving cellulose ester with a poor solvent and an apparatus for mixing and dissolving with a good solvent may be separately provided.

  The type of the pressure vessel used for dissolving the cellulose ester is not particularly limited as long as it can withstand a predetermined pressure and can be heated and stirred under pressure. In addition, instruments such as a pressure gauge and a thermometer are appropriately disposed in the pressurized container. The pressurization may be performed by a method of injecting an inert gas such as nitrogen gas or by increasing the vapor pressure of the solvent by heating. Heating is preferably performed from the outside. For example, a jacket type is preferable because temperature control is easy.

  The heating temperature after adding the solvent is higher than the boiling point of the solvent to be used. In the case of two or more mixed solvents, the heating temperature is higher than the boiling point of the lower boiling solvent and the solvent does not boil. Is preferred. If the heating temperature is too high, the required pressure increases and productivity decreases. The range of preferable heating temperature is 20-120 degreeC, 30-100 degreeC is more preferable, The range of 40-80 degreeC is further more preferable. The pressure is adjusted so that the solvent does not boil at the set temperature.

  In addition to cellulose ester and solvent, additives such as necessary plasticizers and UV absorbers can be mixed with the solvent in advance, dissolved or dispersed, and then added to the solvent before dissolving the cellulose ester. It may be put into the dope.

  After dissolving the cellulose ester, it is taken out from the container while cooling, or it is taken out from the container with a pump or the like and cooled with a heat exchanger or the like, and the resulting polymer dope is used for film formation. May be cooled to room temperature.

  The particle size d of the cellulose ester as a raw material is such that particles having a size of 0.1 mm ≦ d ≦ 20 mm are constituted at a ratio of 60% by weight or more, so that good solubility can be obtained without generating an aggregate of cellulose ester. Desirable to get.

  The mixture of the raw material cellulose ester and the solvent is dissolved in a dissolving kettle having a stirrer, and at this time, the peripheral speed of the stirring blade is preferably at least 0.5 m / second or more and stirred and dissolved for 30 minutes or more.

  In the method of the present invention, the cellulose ester dope dissolved in the dissolution vessel is sent to a filter by a pump and filtered in the filter. This filtration can be performed by a normal method, but the method of filtering while heating under pressure at a temperature not lower than the boiling point of the solvent at normal pressure and in a range where the solvent does not boil is the differential pressure before and after the filter medium (hereinafter referred to as the pressure difference). The increase in the pressure may be small, which is preferable.

  In the method of the present invention, the cellulose ester dope is filtered to remove foreign matters, particularly foreign matters that are mistakenly recognized as images in a liquid crystal image display device. It may be said that the quality of the protective film for polarizing plates is determined by this filtration.

  Filter media used for filtration preferably have a low absolute filtration accuracy. However, if the absolute filtration accuracy is too low, the filter media is likely to be clogged, and the filter media must be frequently replaced, resulting in increased productivity. There is a problem of lowering.

  For this reason, in the method of the present invention, the filter medium used for the cellulose ester dope preferably has an absolute filtration accuracy of 0.020 mm or less. As the filter paper, for example, No. of Azumi Filter Paper Co., Ltd., a commercially available product. 244, 277, etc. can be mentioned and used preferably.

  There are no particular restrictions on the material of the filter medium, and normal filter media can be used. However, plastic fiber filter media such as polypropylene and Teflon (registered trademark), and metal filter media such as stainless steel fibers are used to remove fibers. This is preferable.

  The preferable temperature range of dope filtration is 45-120 degreeC, 45-70 degreeC is more preferable, and it is further more preferable that it is the range of 45-55 degreeC.

  The filtration pressure is preferably 3500 kPa or less, more preferably 3000 kPa or less, and even more preferably 2500 kPa or less. The filtration pressure can be controlled by appropriately selecting the filtration flow rate and the filtration area. The dope thus obtained is stored in a stock tank, defoamed and then used for casting.

  Thus, when the dope is prepared by previously mixing the domain forming material, the cellulose ester, and the solvent in the dissolution vessel, it is usually unnecessary to add the domain forming material in-line. However, if necessary, all or part of the domain forming material can be mixed in-line.

  For example, an amorphous particle dispersion mixed or dispersed in a suitable solvent in a dissolution vessel is sent to a filter by a pump and filtered in the filter. The obtained dope is stored in the second stock tank and defoamed.

  Cellulose ester solution (or sometimes referred to as dope stock solution) transferred from the first stock tank by a pump and a domain-forming material solution (amorphous particle dispersion) transferred from the second stock tank by a pump. Is merged with a merge pipe.

  A filter is arranged immediately before the junction tube, and for example, lump and large foreign matter generated from the path due to exchange of filter media etc. can be removed from the amorphous particle dispersion or dope stock solution being fed. . Here, a metal filter having solvent resistance is preferably used.

  The filter medium is preferably a metal, particularly stainless steel, from the viewpoint of durability. From the viewpoint of clogging, it is preferable to have a porosity of 60 to 80%. Most preferably, the filtration is performed with a metal filter medium having an absolute filtration accuracy of 30 to 60 μm and a porosity of 60 to 80%, so that coarse foreign substances can be reliably removed over a long period of time. preferable. Examples of the metal filter medium having an absolute filtration accuracy of 30 to 60 μm and a porosity of 60 to 80% include NF-10, NF-12, and NF-13 of Finepore NF series manufactured by Nippon Seisen Co., Ltd. be able to.

  The two liquids combined as described above are transported in a layered manner in the conduit, and are difficult to mix as they are. Therefore, the two liquids are merged and then transferred to the next step while being sufficiently mixed by a mixer (19) such as an in-line mixer.

  As an in-line mixer that can be used in the present invention, for example, a static mixer SWJ (Toray static type in-pipe mixer, Hi-Mixer, manufactured by Toray Engineering) is preferable.

  An optical film manufacturing method using a solution casting film forming method is a method in which a dope adjusted by a melting pot is fed to a casting die and is transferred infinitely, for example, on a support made of a rotationally driven stainless steel endless belt. In position, the dope is cast from the casting die.

  As the casting die, a pressure die that can adjust the slit shape of the die part and easily make the film thickness uniform is preferable. Further, in the casting die, the angle formed between the inner slit wall surface and the support surface is preferably 40 to 90 °, particularly preferably 60 to 75 °.

  The gap between the die lip of the casting die and the support surface is preferably set with a gap of 0.2 to 10 mm, more preferably a gap of 0.5 to 5 mm. The slit gap of the casting die is preferably 0.05 to 1.5 mm, more preferably 0.15 to 1.0 mm.

  The surface roughness Ra of the support is from 0.0001 to 1 μm, more preferably from 0.0003 to 0.1 μm, and further preferably from 0.0005 to 0.05 μm.

  In a film forming apparatus having a rotationally driven endless belt as a support, the belt support is disposed between a pair of front and rear drums and an intermediate portion thereof, and supports an upper transition portion and a lower transition portion of the endless belt support from the back side. Consists of multiple support roles.

  In addition, one or both of the drums at both ends of the rotary drive endless belt support are provided with a drive device that applies tension to the belt support, and the belt support is tensioned and tensioned. Used in.

  When an endless belt is used as the support, the belt temperature during film formation can be cast at a temperature in the general temperature range of 0 ° C. to less than the boiling point of the solvent. A range of −5 ° C. is more preferable. At this time, it is necessary to control the ambient atmospheric humidity above the dew point.

  In addition, when the support transport speed is 10 m / min or more, the casting film coming out from the lip of the casting die is depressurized to cause air mixing and a horizontal streak in the width direction of the film. In order to suppress flapping of the drawn ribbon, it is preferable to provide a decompression chamber upstream of the casting die and decompress the pressure by 10 to 600 Pa, and more preferably 10 to 200 Pa.

  The gap between the lower end face of the decompression chamber and the support surface is in the range of 0.5 to 5 mm because the suction air volume does not become too large, thereby suppressing the generation of the dope dry film at the end of the casting die lip. desirable.

  In order to increase the film forming speed, two or more pressure casting dies may be provided on the casting support, and the dope amount may be divided to form a multilayer film.

  When casting the dope onto the support, it is preferable to control the temperature below the boiling point of the solvent used for dissolving the raw polymer and below the boiling point of the solvent having the lowest boiling point in the mixed solvent.

  In the method using an endless belt as a support, the web is dried and solidified until the web has a film strength that can be peeled off from the support by a peeling roll, so that the residual solvent amount in the web is reduced to 150% by weight or less. Preferably, 80 to 120% by weight is more preferable. Moreover, as for the web temperature when peeling a web from a support body, 0-30 degreeC is preferable. In addition, immediately after the web is peeled off from the support, the temperature once drops rapidly due to solvent evaporation from the support close-contact surface side, and volatile components such as water vapor and solvent vapor in the atmosphere tend to condense. The web temperature is more preferably 5 to 30 ° C.

  Here, the residual solvent amount can be expressed by the following equation.

Residual solvent amount (% by weight) = {(M−N) / N} × 100
In the formula, M is the weight of the web at an arbitrary time point, and N is the weight when the weight M is dried at 110 ° C. for 3 hours.

  In this step, the dope film (web) formed by the dope cast on the endless belt support is heated on the support, and the solvent is evaporated until the web can be peeled from the support by a peeling roll.

  In order to evaporate the solvent, there are a method of blowing air from the web side, a method of transferring heat from the back surface of the support by liquid, a method of transferring heat from the front and back by radiant heat, and the like.

  In the method using an endless belt as the support, the peeling tension is usually 20 to 25 kg / m when the belt support and the web are peeled off by the peeling roll. In the optical film produced according to the invention, since the web is likely to wrinkle at the time of peeling, it is preferable to peel at a minimum tension of 17 kg / m, more preferably at a minimum tension of 14 kg / m. It is.

  In the system using an endless belt as the support, the peeled web is introduced into the initial drying zone. In the initial drying zone, the web is meandered by a plurality of transport rolls arranged in a staggered manner as viewed from the side, during which the web is blown from the front part of the bottom of the initial drying zone and behind the ceiling of the initial drying zone. It is dried by the hot air discharged from the close part.

  In the method for producing an optical film according to the present invention, the residual solvent amount of the web when peeling the web from the belt support is 80 to 170% by weight, and the residual solvent amount of the web when entering the tenter is 2 to 20% by weight. The drying temperature in the initial drying zone between them is preferably 60 to 110 ° C.

  In the method for producing an optical film by the solution casting film forming method of the present invention, when a rotary drive drum is used as a support, a dope is prepared in the same manner as described above, and the dope is transferred from a casting die to a hard chromium plating. A web is obtained by casting on the applied drum support, and the web is peeled off by a peeling roll when the web moves approximately 3/4 rounds by the rotation of the drum support.

  The dope is fed to the casting die through a pressurized metering gear pump, and the dope is cast from the casting die onto a support made of a drum at the casting position.

  When a drum is used as the support, the temperature of the drum during film formation is preferably cooled to 10 ° C. or lower, more preferably 0 ° C. or lower, and further to -10 ° C. or lower. preferable. The dope cast on the drum surface increases the gel film strength (film strength) by cooling gelation, and the gel film strength (film strength) is also improved by promoting drying until stripping. To increase.

  In the system using a drum as the support, the drum is preferably cooled to 10 ° C. or lower, and the temperature of the drum is preferably 0 ° C. or lower in order to dry and solidify the web until the web has a peelable film strength from the support. More preferably, it is cooled to -10 ° C or lower.

  In the method for producing an optical film according to the present invention, even in a system using a drum as a support, the residual solvent amount of the web when peeling the web from the drum support is 80 to 170% by weight, and the web remains when entering the tenter. The amount of solvent is preferably 2 to 20% by weight, and the drying temperature in the initial drying zone between these is preferably 60 to 110 ° C.

  Next, in either the method using an endless belt as the support or the method using a rotary drive drum, the side edges of the web (or film) are fixed with clips or the like for the production of a film for an image display member. Tenter systems that are stretched by stretching are known, and are preferred for improving flatness and dimensional stability.

  In particular, in the initial drying zone after peeling from the support, the web (or film) tends to shrink in the width direction by evaporation of the solvent. Shrinkage increases with drying at higher temperatures. Drying while suppressing this shrinkage as much as possible is preferable for improving the flatness of the finished film.

  In the stretching step with a tenter, for example, the stretching ratio when producing a cellulose ester film is 1.01 to 3 times, preferably 1.5 to 3 times, with respect to the film forming direction or the width direction. . When stretching in the biaxial direction, the side to be stretched at a high magnification is 1.01 to 3 times, preferably 1.5 to 3 times, and the stretching ratio in the other direction is 0.8 to 1.5. The film can be stretched by a factor of preferably 0.9 to 1.2.

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

  In the stretching process using a tenter, the web is blown from the front part of the bottom of the tenter, and the web is dried together with the stretching by warm air discharged from the rear part of the ceiling of the tenter.

  It is preferable to provide a post-drying device after the stretching step using a tenter. In the post-drying apparatus, the web is meandered by a plurality of conveying rolls arranged in a staggered manner as viewed from the side, and the web is dried in the meantime. The film transport tension in the post-drying apparatus is affected by the physical properties of the dope, the amount of residual solvent in the peeling and film transporting process, the temperature in the post-drying apparatus, etc., but is preferably 30 to 250 N / m, 60 -150 N / m is more preferable. 80 to 120 N / m is most preferable.

  The means for drying the web (or film) is not particularly limited, and is generally performed with hot air, infrared rays, a heating roll, microwaves, or the like. It is preferable to dry with hot air from the viewpoint of simplicity. For example, it is blown from the front portion of the bottom of the post-drying device and dried by warm air discharged from the rear portion of the ceiling of the post-drying device. The drying temperature is preferably 40 to 160 ° C, and more preferably 50 to 160 ° C in order to improve the flatness and dimensional stability.

  These steps from casting to post-drying may be performed in an air atmosphere or in an inert gas atmosphere such as nitrogen gas. In this case, it goes without saying that the dry atmosphere is carried out in consideration of the explosion limit concentration of the solvent.

  The web conveyance tension at the time of drying is 30 to 300 N / width m, and 40 to 270 N / width m is more preferable.

  It is preferred to arrange a web (or film) surface cleaning device before and / or after the drying step and / or the thermal straightening device.

  The cleaning device applies ultrasonic vibration to the web (or film) in the middle of conveyance, blows high-pressure air onto the surface, blows off the adhering matter and sucks it, and removes adhering dust and the like. . In addition, known means and methods such as a method for performing flame treatment (corona treatment, plasma treatment) and a method for installing an adhesive roll can be used without any particular limitation.

  In addition, the cleaning means to arrange | position may be single and may be two or more.

  Since adhesion of dust or the like to the web is often due to the action of static electricity, it is preferable to dispose static electricity on the web by disposing a static elimination means, for example, a static elimination bar, in front of the cleaning device. As the charge removal bar, a known bar can be used without any particular limitation.

  In the drying process, as a measure to suppress the phenomenon that the plasticizer contained in the web (or film) evaporates and condenses on the rolls and wall surfaces, a fresh gas of a specific amount or more is allowed to flow into the supply air volume per unit time. It is preferable. And it is preferable to set the quantity of the fresh gas supplied to 5 to 50% of the total supply air volume.

  The reason why the supply amount of fresh gas is 5 to 50% is that if the amount is less than 5%, the amount of fresh gas is too small to suppress the plasticizer condensation. If the amount exceeds 50%, the amount of fresh gas is too large. This is because the running cost increases waste.

  In addition to the above measures, for example, the following configuration can be adopted. First, a configuration in which a part of the air in the drying / correction process chamber is circulated and the plasticizer is forcibly removed by passing it through a cooler coil or the like and then raised to a specified temperature with a heater. A configuration in which the temperature of the portion in contact with the metal surface is increased, for example, a configuration in which the temperature of the portion in contact with the metal surface is increased by a steam / surface heater or the like. Third, fresh air is supplied to lower the vapor pressure of the plasticizer on the roll surface. As a means for supplying fresh air, a configuration in which a slit is provided in the width direction in the vicinity of the roll and air is supplied from the punch plate box to suppress the air velocity distribution of the supplied air is used. It is not something.

  In addition, it is preferable that the film temperature at the time of taking out a film from a drying process or a heat correction process chamber or the cooling process of the film which came out of them shall be 60 degrees C or less.

  Here, it is because it is in the conditions which are easy to generate | occur | produce the condensation of a plasticizer when it carries out from the correction | amendment and cooling process box at the temperature exceeding 60 degreeC.

  It is preferable to provide a tension cut roll for the purpose of preventing the film from stretching in the transport direction in the post-drying apparatus. After drying, it is preferable to provide a slitter and cut off the end portion before winding to obtain a good winding shape.

  Next, embossing provided on both side edges of the polymer film will be described. The polymer film that has finished the transport drying process is subjected to processing for forming an emboss on the film by an embossing apparatus prior to introduction into the winding process. As an embossing apparatus, an apparatus described in JP-A-63-74850 can be used.

  Here, the height h (μm) of the emboss is set in the range of 0.05 to 0.3 times the film thickness T, and the width W is set in the range of 0.005 to 0.02 times the film width L. . For example, when the film thickness is 40 μm and the film width is 100 cm, the thickness of the emboss 31 is set to 2 to 12 μm and the emboss width is set to 5 to 30 mm.

  Embossing may be formed on both sides of the film. In this case, the height h1 + h2 (μm) of the emboss is set in the range of 0.05 to 0.3 times the film thickness T, and the width W is set in the range of 0.005 to 0.02 times the film width L. For example, when the film thickness is 40 μm, the emboss height h 1 + h 2 (μm) is set to 2 to 12 μm. The emboss width is set to 5 to 30 mm.

  The lower limit of the embossed height is from the height necessary to prevent partial uneven adhesion between the films. On the other hand, the upper limit is too high, and the embossed shape is too high. This is because it deforms to induce a failure.

  Regarding the width of the emboss, the embossed part will eventually become a loss part, but it is desirable to reduce it. For example, when the film thickness is reduced from 80 μm to 40 μm, the frictional force between the film and the roll becomes 50 μm as a boundary. It was found that the grip force was extremely reduced, and when the film-forming speed was increased to 30 m / min or more, it was found that the friction force between the film and the roll was extremely reduced especially at 50 m / min or more. did. For this reason, the emboss width is the minimum necessary for suppressing slipping of the film, particularly when a high-speed film formation of 50 m / min or more is performed with a thin film of 50 μm or less. However, it is also linked to the height of the above-mentioned embossing, and the embossing height × embossing width for clearing all of the pyramid shape, horse back, polygonal shape, and winding slip failure is determined. In addition, embossing can be arrange | positioned not only at the both ends of a film but at the center part.

  In the present invention, it is preferable that a static eliminator is installed before winding and immediately after the winding unit to neutralize the film.

  The static eliminator can be configured in such a way that a reverse potential is applied by a static eliminator or a forced charging device at the time of winding so that the charging potential when the original winding is re-drawn is ± 2 KV or less. It can also be set as the structure which static-eliminates with the static elimination device converted into positive / negative alternately at 1-150Hz.

  Moreover, it can replace with said static elimination device and can utilize the ionizer and static elimination bar which generate | occur | produce ion wind. Here, the ionizer static elimination is performed by blowing an ion wind toward the film wound up from the embossing device through the transport roll. The ion wind is generated by a static eliminator. Any known static eliminator can be used without limitation.

  The static elimination at the time of film formation winding is to induce coating unevenness when the charged potential is ± 2KV or more when the original film is redrawn and the functional film is applied. Especially when pursuing thin film and high speed Since film peeling electrification at the time of re-feeding becomes high, static elimination during film formation is essential.

  In this process, the film after drying is wound up by a winding device to obtain the original winding of the optical film. A film having good dimensional stability can be obtained by setting the residual solvent amount of the film to be dried to 0.5% by weight or less, preferably 0.1% by weight or less.

  The winding method of the film may be a generally used winder, and there are methods for controlling the tension such as a constant torque method, a constant tension method, a taper tension method, a program tension control method with a constant internal stress, etc. Use it properly.

  The film may be joined to the winding core (winding core) by either a double-sided adhesive tape or a single-sided adhesive tape.

  At the start of the initial winding, it is preferable that the winding tension is 280 N / m width or less and only the embossed portion is wound so that the pressing force of the touch roll winding + the initial winding tension is 60 N / m width or more.

  In the method for producing an optical film according to the present invention, a resin solution (dope) containing a thermoplastic resin and an additive such as a plasticizer and an ultraviolet absorber is allowed to flow on a metal rotating drum or a metal rotating endless belt (support). To form a web, peel the web from the support, and then stretch the peeled web with a tenter and wind the film after drying, on the surface of the transport film before winding, An organopolysiloxane or a solution thereof as a film friction coefficient reducing agent of 0.0001 to 0.03 parts by weight with respect to 100 parts by weight of a thermoplastic resin is applied or sprayed by spraying.

  That is, as usual, cellulose ester, plasticizer, ultraviolet absorber and the like are dissolved in an organic solvent to prepare a dope, a film is formed by a solution casting film forming method, and when the film is wound up after completion of drying, Or it is made to exist in the film surface by post-processing in at least one place after the completion | finish of drying after the completion | finish of drying.

  Post-treatment is a solution in which organopolysiloxane is dissolved in an organic solvent or a soluble solvent such as water, or a low molecular weight liquid organopolysiloxane is applied to the film surface or sprayed by spraying. It is.

  In order to reduce the friction coefficient at both ends in the width direction of the film, a film friction coefficient reducing agent made of organopolysiloxane is present on the film surface, and the friction coefficient at the center in the width direction of the film is the end in the width direction of the film. Post-processing is performed so as to be larger than the film friction coefficient.

  Although the film thickness of the optical film varies depending on the purpose of use, the finished film is usually preferably in the range of 35 to 85 μm, and particularly in the range of 40 to 80 μm as the film for a liquid crystal image display device.

  To adjust the film thickness, it is necessary to control the dope concentration, the pumping amount of the pump, the slit gap of the die base, the extrusion pressure of the die, the speed of the casting support, etc. so as to obtain the desired thickness. Good.

  Further, as a means for making the film thickness uniform, it is preferable that the film thickness detecting means is used to feed back the programmed feedback information to each of the above devices and adjust it.

In the present invention, the optical film preferably has a tensile strength of 90 to 170 N / mm ² in both the MD direction and the TD direction, and particularly preferably 120 to 160 N / mm ² .

  The moisture content is preferably 0.1 to 5%, more preferably 0.3 to 4%, and still more preferably 0.5 to 2%.

  In the present invention, the optical film desirably has a transmittance of 90% or more, more preferably 92% or more, and still more preferably 93% or more. Further, the haze is preferably 0.5% or less, particularly preferably 0.1% or less, and more preferably 0%.

  In the present invention, in the optical film, the curl value preferably has a smaller absolute value, and the deformation direction may be the + direction or the-direction. The absolute value of the curl value is preferably 30 or less, more preferably 20 or less, and particularly preferably 10 or less. The curl value is expressed by a radius of curvature (1 / m).

  By using the protective film for a polarizing plate comprising the optical film of the present invention, it is possible to provide a polarizing plate excellent in durability, dimensional stability, and optical isotropy as well as thinning.

  Here, the polarizing film is obtained by longitudinally stretching a conventionally used film, such as a polyvinyl alcohol film, that can be stretched and oriented with a dichroic dye such as iodine. Since the polarizing film itself does not have sufficient strength and durability, a polarizing plate is generally obtained by adhering a cellulose triacetate film having no anisotropy as a protective film to both sides thereof.

  In the above, the polarizing plate may be prepared by laminating the retardation film of the present invention to the polarizing plate, or the retardation film of the present invention also serves as a protective film and directly pasted to the polarizing film. It may be produced. The method of bonding is not particularly limited, but can be performed with an adhesive composed of an aqueous solution of a water-soluble polymer. The water-soluble polymer adhesive is preferably a completely saponified polyvinyl alcohol aqueous solution. Furthermore, as described above, a long polarizing plate can be obtained by laminating a long polarizing film stretched in the longitudinal direction and treated with a dichroic dye and a long retardation film of the present invention. . The polarizing plate is a sticking type in which a peelable sheet is laminated on one or both sides thereof via a pressure sensitive adhesive layer (for example, an acrylic pressure sensitive adhesive layer). Or the like can be easily attached).

  Said polarizing plate can be produced by a general method. For example, there is a method in which a cellulose ester film is subjected to alkali saponification treatment, and a polyvinyl alcohol film is immersed and stretched in an iodine solution, and bonded to both surfaces using a completely saponified polyvinyl alcohol aqueous solution. The alkali saponification treatment refers to a treatment of immersing the cellulose ester film in a high-temperature strong alkaline solution in order to improve the wetness of the water-based adhesive and improve the adhesiveness.

  In the present invention, the optical film includes a hard coat layer, an antiglare layer, an antireflection layer, an antifouling layer, an antistatic layer, a conductive layer, an optical anisotropic layer, a liquid crystal layer, an alignment layer, an adhesive layer, an adhesive layer, a lower layer. Various functional layers such as a pulling layer can be provided. These functional layers can be provided by a method such as coating or vapor deposition, sputtering, plasma CVD, or atmospheric pressure plasma treatment.

  Further, the polarizing plate constitutes at least one of the two polarizing plate protective films disposed on both sides of the polarizing film, and the polarizing plate thus obtained is A liquid crystal display device is obtained by using one or both surfaces of the liquid crystal cell.

  By using the protective film for a polarizing plate comprising the optical film of the present invention, it is possible to provide a polarizing plate excellent in durability, dimensional stability, and optical isotropy as well as thinning.

  Furthermore, a liquid crystal display device using this polarizing plate can maintain stable display performance over a long period of time.

  A liquid crystal display device according to the present invention includes a liquid crystal cell driven in an IPS mode composed of a pair of substrates sandwiching a liquid crystal layer, and a pair of polarizing plates arranged orthogonally on both sides of the liquid crystal cell. The above optical film is provided on the liquid crystal cell side of at least one polarizing plate.

  The present invention also provides an image display device capable of realizing an easy-to-view display having a high contrast ratio over a wide range using the optical film of the present invention, particularly a liquid crystal display device operating in the IPS mode.

  In addition, the optical film according to the present invention can also be used as a base material for an antireflection film or an optical compensation film.

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

Examples 1-8
(Dope composition)
100 parts by weight of cellulose triacetate (Mn = 148000, Mw = 310000, Mw / Mn = 2.1)
Triphenyl phosphate 8 parts by weight Ethylphthalyl ethyl glycolate 2 parts by weight Methylene chloride 440 parts by weight Ethanol 40 parts by weight UV absorber 1 0.5 part by weight (Tinuvin 109, manufactured by Ciba Specialty Chemicals)
Ultraviolet absorber 2 0.5 part by weight (Tinubin 171 manufactured by Ciba Specialty Chemicals)
0.2 parts by weight of silicon dioxide fine particles (Aerosil 972V, manufactured by Nippon Aerosil Co., Ltd.)
The material having the above dope composition was put into a closed container, heated, stirred and completely dissolved and filtered. Subsequently, the dope was uniformly cast to a width of 2000 mm on a stainless steel band support having a width of 2200 mm at a temperature of 35 ° C. using a solution casting film forming apparatus.

  On the stainless steel endless belt support, the solvent was evaporated until the residual solvent amount was 90% by weight, and the web (film) was peeled off from the endless belt support. Next, the peeled web is introduced into the initial drying zone. In the initial drying zone, the web is meandered by a plurality of transport rolls arranged in a staggered manner as viewed from the side, during which the web is blown from the front part of the bottom of the initial drying zone and behind the ceiling of the initial drying zone. It is dried by the hot air discharged from the close part.

  In this example, the residual solvent amount of the web when peeling the web from the belt support is 90% by weight, and the residual solvent amount of the web when entering the tenter is 8% by weight. The temperature was 70 ° C. The conveyance tension in the initial drying zone was 160 to 180N.

  In the tenter, both ends in the width direction (TD direction) of the web were gripped and stretched in the width direction of the web at a stretch ratio of 20%. In the stretching process, warm air is blown at a temperature of 180 ° C. from the hot air blowing means at the front part of the bottom of the tenter, that is, the hot air blowing slit port, and the exhaust air is discharged from the outlet port at the rear part of the tenter ceiling. And dried with the web stretched.

  Next, the stretched film (web) was introduced into a late drying apparatus. The film conveyance tension in the latter drying apparatus was 180 N / m. Moreover, in the latter stage drying apparatus, it dried with the drying wind of the temperature of 120 degreeC injected from the warm air inlet of the front part of this bottom.

  After drying with the latter drying apparatus, both ends of the film are slit to the width of the product by a pair of upper and lower slitters, and the left and right ends of the film after slitting are embossed (knurled) by embossing rings and back rolls, After providing an embossed portion having a width of 10 mm at the end of the film 4, a cellulose triacetate film having a final film width of 2400 mm, a thickness of 5000 m, and a film thickness of 60 μm was prepared.

  In Examples 1 to 6 of the present invention, in order to reduce the friction coefficient at both ends in the width direction of the cellulose triacetate film, first, dimethylpolysiloxane (n = 50 to 100) (compound A1) or phenyl-modified dimethylpolysiloxane Siloxane (m = 25 to 50, p = 25 to 50) (compound B1) is used in the total amount shown in Table 1, respectively. First, dimethylpolysiloxane (compound A1) or phenyl-modified dimethylpolysiloxane (compound A part of B1) is contained in the resin solution (dope), and then each of these dimethylpolysiloxane (compound A1) or phenyl-modified dimethylpolysiloxane (compound B1) acetone solution is dried by a late dryer. Liquid injection equipment installed 5m before the winding device for both ends of the transport film Spraying the by injection, and wound by the winding device.

  In Examples 1 to 6, the total amount of dimethylpolysiloxane (n = 50 to 100) (Compound A1) used was changed as shown in Table 1, and in Examples 7 and 8, The total amount of phenyl-modified dimethylpolysiloxane (m = 25 to 50, p = 25 to 50) (Compound B1) was changed as shown in Table 1 and used.

  Moreover, in Examples 1-8, the ratio of the spraying quantity with respect to dope content of organopolysiloxane was 10%, respectively.

Comparative Examples 1-4
For comparison, a cellulose triacetate film is prepared in the same manner as in Examples 1 to 8, but the difference from Examples 1 to 8 is that Comparative Example 1 does not use dimethylpolysiloxane. It is in the point. In Comparative Examples 2 and 3, dimethylpolysiloxane (n = 50 to 100) (Compound A1) was used as shown in Table 1, with different total amounts of organopolysiloxane used. Furthermore, in Comparative Example 4, dimethylpolysiloxane was not used and a matting agent (silicon dioxide fine particles: Aerosil 972V) was not used.

  For the cellulose triacetate films of Examples 1 to 8 and Comparative Examples 1 to 4 thus obtained, the coefficient of friction of the film surface was measured at both ends of the film and the center of the film. The ratio was calculated and the results obtained are shown in Table 1 below. In addition, the friction coefficient of the film surface was measured based on JISK7125.

  Next, the rollability of each film, that is, the presence or absence of occurrence of wrinkle failure of the film, the occurrence of winding deviation, the presence or absence of blocking after 3 months at room temperature, and the haze were measured and obtained. The results are shown in Table 1 below.

(Evaluation methods)
Film winding properties Presence or absence of wrinkle generation of film The state of winding of the film after winding was observed, and the presence or absence of generation of wrinkles was evaluated by visual observation according to the following ranking.

◎: No wrinkle is generated. ○: Almost no wrinkle is generated. △: Wrinkle is generated. Presence or absence of occurrence of film winding deviation The state of film winding after winding was observed, and the presence or absence of film edge deviation was evaluated by visual observation according to the following ranking.

◎: No film edge misalignment ○: Little film edge misalignment △: Film edge misalignment ×: Film edge misalignment is marked 3.3 Wrinkles and edge misalignment occurred after winding The wound state (wrinkles and edge misalignment) of the film after storing the film at room temperature for 3 months was evaluated by visual observation according to the following ranking.

◎: No wrinkles and end shifts ○: Almost no wrinkles and end shifts △: Wrinkles and end shifts ×: Wrinkles and end shifts are remarkable Presence or absence of occurrence of blocking After winding the rolled-up film at room temperature for 3 months, the film was drawn out, and the blocking (sticking) state between the overlapping films was evaluated by visual observation according to the following ranking.

◎: No blocking ○: Almost no blocking Δ: Slightly blocking ×: Remarkably blocking (film haze)
The film after winding was drawn out to the required length, and 10 locations were selected at random from the film, and measured using a haze meter (1001DP type, manufactured by Nippon Denshoku Industries Co., Ltd.) according to the method defined in JIS K6714. . The obtained results are shown in Table 1 below.

  As is clear from the results in Table 1 above, according to the cellulose triacetate films prepared in Examples 1 to 8 of the present invention, there was no occurrence of wrinkling and misalignment of the film, and there was no wrinkle after 3 months. There was little or no edge misalignment. Further, there was no blocking of the wound film. Thus, the rollability deterioration (winding wrinkles etc.) which deteriorates with the widening of the film could be improved by reducing the friction coefficient at both ends in the width direction of the film. And the haze of the film can be greatly reduced, and even when the stretch ratio is increased to widen the film, the increase in haze can be suppressed and a highly transparent film can be obtained. It was.

  On the other hand, in the cellulose triacetate films of Comparative Examples 1 to 4, no sufficient improvement in film rollability deterioration (winding wrinkles, etc.) was observed, and in Comparative Examples 1 and 3 and 4, the haze of the film was It was high and the transparency was poor.

Examples 9-13
A cellulose triacetate film having a final film width of 2400 mm is produced using the same dope composition as in Example 1, except that the liquid jet installed 5 m before the winding device is different from that in Example 1 above. The entire amount of the various organopolysiloxane liquids shown in Table 2 was sprayed onto the surface of both ends in the width direction of the transport film by means of an apparatus, and then wound by a winder.

In Example 9, a stock solution of polyether-modified dimethylpolysiloxane (m = 2 to 3, p = 2 to 3, scattering and water-soluble) (Compound C) was used. In Example 10, C ₈ H A stock solution of _17- modified dimethylpolysiloxane (m = 1-2, p = 1-2, scattering) (compound D) was used. In Example 11, phenyl-modified dimethylpolysiloxane (m = 1-2, p = A stock solution of 1-2, scatterability (compound B2) was used. In Examples 12 and 13, a stock solution of the same dimethylpolysiloxane (n = 4 to 6, scattering property) (Compound A2) was used. As shown in Table 2, the amounts used were different from each other.

Comparative Examples 5 and 6
For comparison, a cellulose triacetate film is produced in the same manner as in Example 9, except that dimethylpolysiloxane (n = 800) (Compound A3) is different from Comparative Example 5 in Comparative Example 5. ) In the amount shown in Table 2, and in Comparative Example 6, the point that the stock solution of dimethylpolysiloxane (n = 1, scattering property) (compound A4) was used in the amount shown in Table 2. is there.

  For the cellulose triacetate films of Examples 9 to 13 and Comparative Examples 5 and 6 thus obtained, the coefficient of friction of the film surface is measured at both ends of the film and at the center of the film in the same manner as in Examples 1 to 8 above. In addition, the ratio of the film edge friction coefficient / center friction coefficient was calculated, and the obtained results are shown in Table 2 below.

Next, the rollability of each film, that is, the occurrence of wrinkle failure of the film, the occurrence of winding deviation, the presence of blocking after 3 months at room temperature, and the haze were measured and obtained. The results are shown in Table 2 below.

  As is clear from the results in Table 2 above, according to the cellulose triacetate films produced in Examples 9 to 13 of the present invention, there was no film wrinkle failure and no occurrence of winding deviation, and the winding after 3 months passed. There were no wrinkles or edge shifts. Further, there was no blocking of the wound film. Thus, the rollability deterioration (winding wrinkles etc.) which deteriorates with the widening of the film could be improved by reducing the friction coefficient at both ends in the width direction of the film. And the haze of the film can be greatly reduced, and even when the stretch ratio is increased to widen the film, the increase in haze can be suppressed and a highly transparent film can be obtained. It was.

  On the other hand, in the cellulose triacetate films of Comparative Examples 5 and 6, no sufficient improvement in film rollability deterioration (winding wrinkles, etc.) was observed.

Examples 14-28
(Preparation of polarizing film)
Next, a polarizing plate was produced using the cellulose ester films produced in Examples 1 to 8 and Examples 9 to 13, and then a polarizing film was produced in order to produce a liquid crystal display device. That is, a polyvinyl alcohol film having a thickness of 120 μm was uniaxially stretched at a temperature of 110 ° C. and a stretch ratio of 5 times. This was immersed in an aqueous solution consisting of 0.075 g of iodine, 5 g of potassium iodide and 100 g of water for 60 seconds, and then immersed in an aqueous solution of 68 ° C. consisting of 6 g of potassium iodide, 7.5 g of boric acid and 100 g of water. This was washed with water and dried to obtain a polarizing film.

(Preparation of polarizing plate)
Then, according to the following Step 1 to Step 5, the cellulose triacetate film (polarizing plate protective film) having a film thickness of 60 μm prepared in Examples 1 to 13 and a commercially available retardation film are formed on both surfaces of the polarizing film. The polarizing plate was produced by bonding.

  Step 1: A polarizing plate protective film obtained by immersing in a 2 mol / L sodium hydroxide solution at 60 ° C. for 90 seconds, then washing with water and drying to saponify the side to be bonded to the polarizing film, and a commercially available retardation film Obtained.

  Step 2: The polarizing film was immersed in a polyvinyl alcohol adhesive tank having a solid content of 2% by mass for 1 to 2 seconds.

  Step 3: A polarizing plate protective film made of the cellulose triacetate film produced in Examples 1 to 13 prepared in Step 1 on both sides of the polarizing film by lightly wiping off the excess adhesive adhered to the polarizing film in Step 2 And a commercially available retardation film were laminated.

Step 4: Commercial and retardation film laminated in step 3, a polarizing film, a back face side-polarizing plate protective film, a pressure 20-30 N / cm ^2, the conveyance speed was pasted at approximately 2m / min.

  Step 5: A sample in which the polarizing film prepared in Step 4 was bonded to a commercially available retardation film and a polarizing plate protective film was dried in a dryer at 80 ° C. for 5 minutes to prepare a polarizing plate.

(Production of liquid crystal display device)
Next, the polarizing plates on both sides of a commercially available liquid crystal display device (20-inch display manufactured by SONY: model name, KLV-20AP2) are carefully peeled off, and the above-mentioned various polarizing plates are attached to the liquid crystal in the liquid crystal cell. A liquid crystal display device was manufactured by bonding to a glass surface.

  At that time, the polarizing plate is bonded so that the phase difference film surface of each polarizing plate is on the liquid crystal cell side, and the absorption axis is in the same direction as the polarizing plate previously bonded. Then, a liquid crystal display device was produced.

(Visibility evaluation)
In order to evaluate the visibility performance of each of the liquid crystal display devices manufactured in Examples 14 to 28, the liquid crystal display device was stored for 1500 hours under the conditions of a temperature of 60 ° C. and a humidity of 90% RH, and then the liquid crystal display. The apparatus was turned on, and after 6 hours, the presence or absence of visibility deterioration of the display part in black display was comprehensively evaluated, and evaluated according to the following ranks. The results obtained are shown in Table 3 below.

Visibility evaluation rank A: Visibility degradation is not recognized at all O: Visibility degradation is hardly noticed Δ: Visibility degradation is recognized ×: Comparative examples 7 to 12 in which visibility degradation is remarkable
As a comparative example, a polarizing plate and a liquid crystal display device were produced using the cellulose triacetate film produced in Comparative Examples 1 to 6 in the same manner as in Examples 14 to 28.

About each liquid crystal display device produced by these comparative examples 7-12, the performance of visibility degradation was evaluated similarly to the case of Examples 14-28, and the obtained result is shown according to following Table 3 together. It was.

  As is clear from the results of Table 3 above, according to the liquid crystal display devices of Examples 14 to 28 of the present invention, the visibility deterioration of the display unit is not recognized at all, or hardly noticed. A liquid crystal display device excellent in display performance could be manufactured.

  On the other hand, according to the liquid crystal display devices of Comparative Examples 7 to 12, visibility deterioration of the display unit was recognized or remarkable, and the liquid crystal display device was inferior in display performance.

Claims (16)

A film friction coefficient reducing agent is present on the film surface, the coefficient of friction at the center of the film width direction is 0.40 to 1.00, and the coefficient of friction at the end of the film width direction is 0.20 to 0.99. Yes, the film friction coefficient at the center of the film width direction is larger than the film friction coefficient at the end of the film width direction,
Film friction coefficient ratio: edge friction coefficient / center friction coefficient = 0.50-0.99
An optical film, characterized in that   The optical film according to claim 1, wherein the friction coefficient reducing agent is an organopolysiloxane. 3. The optical film according to claim 2, wherein the organopolysiloxane has the following general formula (1) or general formula (2).
General formula (1)
R R ¹
｜ ｜
R-Si- (O-Si-) n-R
｜ ｜
R R
In the formula, R and R ¹ are a methyl group, an ethyl group, an alkyl group having 3 to 14 carbon atoms, a phenyl group, or hydrogen, or at least one hydrogen is fluorine, a polyether group, an amino group, an epoxy group, or a hydroxyl group. A modified methyl group substituted with a carboxyl group, a methacrylate group, an alkoxy group, a modified ethyl group, a modified alkyl group having 3 to 14 carbon atoms, and a modified phenyl group, and R and R ¹ are the same or different. N may be a natural number of 2 to 1000.
General formula (2)
R R ¹ R ²
｜ ｜ ｜
R-Si- (O-Si-) m- (O-Si-) n-R
｜ ｜ ｜
R R R
In the formula, R, R ¹ and R ² are a methyl group, an ethyl group, an alkyl group having 3 to 14 carbon atoms, a phenyl group, or hydrogen, or alternatively at least one hydrogen is fluorine, a polyether group, an amino group, An epoxy group, a hydroxyl group, a carboxyl group, a methacrylate group, a modified methyl group substituted with an alkoxy group, the modified ethyl group, a modified alkyl group having 3 to 14 carbon atoms, and the modified phenyl group, and R ¹ and R ² R and R ¹ , R and R ² may be the same or different, and the sum of the repeating siloxane unit m with R ¹ group and the repeating siloxane unit n with R ² group: m + n = 2 to 1000 is a natural number. In general formula (1) or general formula (2), R is a methyl group, and R ¹ and R ² are a methyl group, an ethyl group, an alkyl group having 3 to 14 carbon atoms, a phenyl group, or hydrogen, Alternatively, at least one hydrogen is modified with fluorine, polyether group, amino group, epoxy group, hydroxyl group, carboxy group, methacrylate group, alkoxy group, modified methyl group, modified ethyl group, modified with 3 to 14 carbon atoms The optical film according to claim 3, wherein the optical film is an alkyl group and a modified phenyl group, and R ¹ and R ² are different substituents.   The optical film according to claim 3 or 4, wherein n in the formula of the general formula (1) or m + n in the formula of the general formula (2) is 2 to 500, respectively.   The n in the formula of the general formula (1) or the m + n in the formula of the general formula (2) is 2 to 100, respectively, according to any one of claims 3 to 5. Optical film.   3. The method for producing an optical film according to claim 1, wherein a resin solution (dope) containing an additive such as a thermoplastic resin and an ultraviolet absorber is applied to a metal rotating drum or a metal rotating endless belt (support). A method for producing an optical film in which a web is formed by casting, the web is peeled off from a support, the peeled web is stretched with a tenter, and the film is wound after drying. Optically characterized in that 0.0001 to 0.03 parts by weight of an organopolysiloxane or a solution thereof as a film friction coefficient reducing agent is sprayed on the surface of 100 parts by weight of a thermoplastic resin by coating or spraying. A method for producing a film.   3. The method for producing an optical film according to claim 1, wherein a resin solution (dope) containing an additive such as a thermoplastic resin and an ultraviolet absorber is applied to a metal rotating drum or a metal rotating endless belt (support). To form a web, peel the web from the support, then stretch the peeled web with a tenter, and wind the film after drying, as a film friction coefficient reducing agent The amount of the organopolysiloxane used is 0.001 to 0.3 parts by weight with respect to 100 parts by weight of the thermoplastic resin as a whole, and a part of the organopolysiloxane is contained in the resin solution (dope), The remainder of organopolysiloxane or its solution is sprayed onto the surface of the transport film before winding by coating or spraying. Ratio of coating or spray amount for doping content of Sun, characterized in that it is a 5-15%, method for producing an optical film.   The method for producing an optical film according to claim 8, wherein a ratio of coating or spraying amount to the dope content of the organopolysiloxane is 7 to 13%.   The method for producing an optical film according to claim 8 or 9, wherein a ratio of coating or spraying amount to the dope content of the organopolysiloxane is 9 to 11%. The method for producing an optical film according to any one of claims 7 to 10, wherein the organopolysiloxane has the following general formula (1) or general formula (2). .
General formula (1)
R R ¹
｜ ｜
R-Si- (O-Si-) n-R
｜ ｜
R R
In the formula, R and R ¹ are a methyl group, an ethyl group, an alkyl group having 3 to 14 carbon atoms, a phenyl group, or hydrogen, or at least one hydrogen is fluorine, a polyether group, an amino group, an epoxy group, or a hydroxyl group. A modified methyl group substituted with a carboxyl group, a methacrylate group, an alkoxy group, a modified ethyl group, a modified alkyl group having 3 to 14 carbon atoms, and a modified phenyl group, and R and R ¹ are the same or different. N may be a natural number of 2 to 1000.
General formula (2)
R R ¹ R ²
｜ ｜ ｜
R-Si- (O-Si-) m- (O-Si-) n-R
｜ ｜ ｜
R R R
In the formula, R, R ¹ and R ² are a methyl group, an ethyl group, an alkyl group having 3 to 14 carbon atoms, a phenyl group, or hydrogen, or alternatively at least one hydrogen is fluorine, a polyether group, an amino group, An epoxy group, a hydroxyl group, a carboxyl group, a methacrylate group, a modified methyl group substituted with an alkoxy group, the modified ethyl group, a modified alkyl group having 3 to 14 carbon atoms, and the modified phenyl group, and R ¹ and R ² R and R ¹ , R and R ² may be the same or different, and the sum of the repeating siloxane unit m with R ¹ group and the repeating siloxane unit n with R ² group: m + n = 2 to 1000 is a natural number. In general formula (1) or general formula (2), R is a methyl group, and R ¹ and R ² are a methyl group, an ethyl group, an alkyl group having 3 to 14 carbon atoms, a phenyl group, or hydrogen, Alternatively, at least one hydrogen is modified with fluorine, polyether group, amino group, epoxy group, hydroxyl group, carboxy group, methacrylate group, alkoxy group, modified methyl group, modified ethyl group, modified with 3 to 14 carbon atoms The method for producing an optical film according to claim 11, which is an alkyl group and a modified phenyl group, wherein R ¹ and R ² are different substituents.   13. The method for producing an optical film according to claim 11, wherein n in the formula of the general formula (1) or m + n in the formula of the general formula (2) is 2 to 500, respectively.   14. The n according to claim 11, wherein n in the formula of the general formula (1) or m + n in the formula of the general formula (2) is 2 to 100, respectively. Manufacturing method of the optical film.   A polarizing plate characterized by using the optical film according to any one of claims 1 to 6 on at least one surface.   A display device using the polarizing plate according to claim 15.