KR20110039549A - Optical film, process for producing same, polarizer employing optical film, and display device - Google Patents

Abstract

In manufacture of the optical film by the melt casting film forming method, the peelability deterioration of the casting film which arises when the film forming speed is raised is solved, the releasability (peelability) of a film is improved, and it has the optical characteristic excellent in transparency and planarity, Moreover, it provides the optical film which can respond to the request of thin film, widening width, and high quality of a protective film for polarizing plates, its manufacturing method, the polarizing plate using an optical film, and a display apparatus. A method for producing an optical film by a melt casting film forming method, comprising: a step of forming a flexible film by casting a resin melt containing a thermoplastic resin and an additive on a surface of a metal support; The surface treatment film is formed on the surface of the metal support over almost the entire width of the metal support by the atmospheric pressure plasma irradiation treatment or the excimer ultraviolet irradiation treatment performed in the presence of the vapor used for the vapor of the additive and the atmospheric pressure plasma irradiation or the excimer ultraviolet irradiation. To have a process.

Description

Optical film, its manufacturing method, polarizing plate and display device using optical film {OPTICAL FILM, PROCESS FOR PRODUCING SAME, POLARIZER EMPLOYING OPTICAL FILM, AND DISPLAY DEVICE}

The present invention provides a method for producing an optical film that can be used for various functional films such as a protective film for a polarizing plate used in a liquid crystal display (LCD), a retardation film, a viewing angle expanding film, an antireflection film used for a plasma display, an optical film, and a polarizing plate. And a display device.

In recent years, liquid crystal displays have been used in televisions and large-scale monitors due to the improvement of their image quality and the improvement of high-definition technology. It has become strong and widening of the optical film is demanded.

In addition, in recent years, in order to cope with the rapid expansion of the liquid crystal TV, the demand of the optical film is also rapidly increasing, and productivity improvement is strongly demanded.

The manufacturing method of an optical film is divided roughly into the melt casting film forming method and the solution casting film forming method. The former is a method in which the polymer is heated and melted, the melt is cast on the support, cooled and solidified, then peeled off from the support, and stretched as necessary to produce a film. The latter is a method in which a polymer is dissolved in a solvent, the solution (dope) is cast on a support, the solvent is evaporated with warm air, hot water or the like, then peeled from the support, and further stretched as necessary to produce a film.

Since the solution casting film forming method uses a large amount of solvents, no solvent is used in the melt casting film forming method, a production rate that does not depend on the drying rate can be obtained, and productivity can be expected to be improved.

Here, since the thermal stability of resin itself is low, natural polymers, such as cellulose, add a large amount of additives, for example, a plasticizer, an ultraviolet absorber, a retardation control agent, a peeling enhancer, an antioxidant, and a thermal decomposition inhibitor. Evaporate from the surface of the hot film from the casting die.

Here, when the film forming rate is low, the film temperature decreases before the cast film reaches the cooling support, so that the evaporation of the additive is also stabilized.

On the other hand, when the film forming speed increases, the hot cast film from the casting die reaches the cooling support before the temperature decreases, and the additive evaporated from the film condenses on the surface of the cooling support. In that part, there existed a problem that peeling force of the casting film from a cooling support increases, and peeling worsened.

As a result, since peeling stress is applied to a flexible film | membrane when peeling off, a small cross-sectional deformation | transformation arises.

As described above, there is a problem of deterioration of the peelability of the cooling support and a film formation at a low production rate.

Patent Document 1 discloses a method and apparatus for producing a resin coated (laminate) paper, particularly a laminating apparatus including a step of coating a molten resin, the method for cleaning a cooling roll for removing a low molecular component adhering to a cooling roll. The method of applying energy to the surface of a cooling roll using the flame of a high power laser light source or a frame burner as a cleaning method is described.

In addition, Patent Document 2 discloses a method of irradiating ultraviolet rays to a roll surface used for producing a film to remove deposits on the roll surface.

In addition, Patent Document 3 discloses a cooling roll by irradiating plasma to a cooling roll in contact with a traveling film in order to reduce film surface scratches generated in the film forming process of the thermoplastic resin film and to clean the contamination adhered to the cooling roll. A method for removing adhered organic matter is disclosed.

Japanese Patent Laid-Open No. 2002-240125 Japanese Patent Laid-Open No. 2003-89142 Japanese Patent Laid-Open No. 2001-62911

However, all of the methods described in Patent Documents 1 to 3 clean the rolls, and even the rolls whose surfaces have been cleaned by the conventional cleaning method, such that the web is contaminated by the bleed-out of the additives next time. When this conveyance is carried out, while an additive adheres to a roll, the peeling force increases in the adhesion part of the additive, and there exists a high risk of creating a deformation | transformation of a film at the time of peeling.

When such peeling stress is applied to generate a slight deformation on the surface of the film, the deformation itself also causes deterioration of the smoothness of the film, and thus there is a problem that it cannot be adapted to the recent fixed color and high definition liquid crystal screen.

In addition, in the part where the peel stress is increased, the optical and mechanical properties of the film also cause a difference with the part where the peel stress is not increased, and the difference in the retardation value and the increase in transmittance in the cross nicol state (CNT) accompanying it, Thereby, there existed a problem of causing the black mold-shaped unevenness and the rise of a haze by the dispersion | variation in the contrast at the time of using a liquid crystal panel.

Moreover, when apply | coating an antireflection layer, a reduction layer, a surface hardening layer, etc. to the surface of an optical film, there existed a problem that a cratering failure arises or a coating layer becomes easy to become uneven because wettability differs from the periphery.

DISCLOSURE OF THE INVENTION An object of the present invention is to solve the problems of the prior art described above, and in the method for producing an optical film by the melt cast film forming method, when the film forming rate is increased, the peeling property of the cast film deteriorates due to the condensation of additive vapor on the cooling support. It is to improve productivity by eliminating the problem.

Furthermore, by improving the releasability (peelability) of the film from the cooling support, an optical film having optical properties excellent in transparency and planarity can be produced to meet the demands of thinning, widening and high quality of protective films for polarizing plates and the like. It is providing the film, its manufacturing method, the polarizing plate using an optical film, and a display apparatus.

MEANS TO SOLVE THE PROBLEM In order to solve the said subject, this invention has the following characteristics.

1. A method for producing an optical film by a melt cast film forming method, comprising: a step of forming a cast film by casting a resin melt containing a thermoplastic resin and an additive on a surface of a metal support, and cooling and solidifying the cast film, followed by peeling from the metal support. And the atmospheric pressure plasma irradiation treatment or excimer ultraviolet irradiation treatment performed in the presence of a gas used for vapor and atmospheric pressure plasma irradiation or excimer ultraviolet irradiation of the additive, and the metal support over almost the entire width of the metal support. It has a process of forming a surface treatment film on the surface, The manufacturing method of the optical film characterized by the above-mentioned.

2. The step of forming the surface treatment film on the surface of the metal support is performed before the resin melt is cast on the surface of the metal support, and after forming the surface treatment film on the surface of the metal support in advance, the flexible film is formed. The manufacturing method of the optical film of said 1 characterized by the above-mentioned.

3. The step of forming a surface treatment film on the surface of the metal support is performed simultaneously with the step of casting the resin melt on the surface of the metal support in a non-passing section of the cast film on the surface of the metal support. The manufacturing method of the said optical film of 1 described above.

4. The position at which the atmospheric pressure plasma irradiation treatment or the excimer ultraviolet irradiation treatment is performed is near the position where the resin solution in which a large amount of vapor of the additive is present is cast on the surface of the metal support. The manufacturing method of the described optical film.

5. Said vapor is vapor of plasticizer or ultraviolet absorber, The manufacturing method of optical film in any one of said 1-4 characterized by the above-mentioned.

6. Said normal temperature plasma irradiation process is 1 W / cm <2> or more and 50 W / cm <2> (area of the area which discharge generate | occur | produces) supplying between electrodes as processing conditions, The said description in any one of said 1-5. Method for producing an optical film.

7. Said excimer ultraviolet irradiation process irradiates the ultraviolet-ray whose main wavelength is 172 nm as light quantity of 1-3,000mJ / cm <2> as processing conditions, The manufacturing method of the optical film in any one of said 1-5 characterized by the above-mentioned. .

8. Said surface treatment film | membrane has 5-40 degree of contact angles of said surface treatment film and water, The manufacturing method of the optical film in any one of said 1-7 characterized by the above-mentioned.

9. Said thermoplastic resin is cellulose ester-type resin, The manufacturing method of optical film in any one of said 1-8 characterized by the above-mentioned.

10. The method for producing an optical film according to any one of 1 to 9 above, wherein the metal support is any one of an endless belt, a drum, or a roll for film forming.

11. The minimum increase in peel force required to peel off the flexible film after cooling from the surface of the metal support is in the range of 0.1 to 2.0 (N / m) at the start of film formation and 24 hours after film formation. The manufacturing method of the optical film as described in any one of said 1-10 made into them.

12. The optical film manufactured by the manufacturing method of the optical film in any one of said 1-11.

13. The deviation of the transmittance | permeability in wavelength 600nm at the time of cross nicol of the said optical film exists in the range of 2 * 10 <^-5> -60 * 10 <^-5> (%), The optical film of said 12 characterized by the above-mentioned.

14. The optical film as described in said 12 or 13 is provided in at least one surface, The polarizing plate characterized by the above-mentioned.

15. The display device using the polarizing plate of said 14 characterized by the above-mentioned.

According to the invention of the method for producing an optical film of claim 1, by performing an atmospheric pressure plasma irradiation treatment or an excimer ultraviolet irradiation treatment, a very dense surface treatment film is formed on the surface of the metal support having a decomposition product of an additive such as a plasticizer as a component. By the presence of the surface treatment film, the releasability (peelability) of the film from the surface of the metal support is remarkably improved to obtain very smooth peelability, the variation in the width direction of the peeling position is reduced, and the retardation (Re) value It is possible to manufacture an optical film having optical properties excellent in transparency and planarity due to the drastic reduction of the deviation, and to increase the production speed, thereby improving the productivity of the film. It has an effect that it can meet the demand for widening and high quality.

According to the invention of the optical film of claim 12, the releasability (peelability) of the film from the metal support is improved, very smooth peelability is obtained, and the optical film has a film width from the point that the variation in the width direction of the peeling position is reduced. The variation of the retardation (Re) value in the direction and the longitudinal direction is greatly reduced, thereby exhibiting the effect of excellent transparency and planarity.

According to the invention of the polarizing plate of claim 14, since the variation in the retardation (Re) value is greatly reduced and the optical film according to claim 12 or 13 having excellent transparency and planarity is provided on at least one side, the polarizing plate is also retardation (Re). The dispersion | variation in a value reduces and exhibits the effect that it is excellent in transparency and planarity.

According to the invention of the display device of claim 15, since the variation in retardation (Re) value is reduced and the polarizing plate according to claim 14 which is excellent in transparency and planarity is used, there is a case where contrast reduction and lightness unevenness of the liquid crystal panel are generated. There is no effect that it is excellent in visibility.

According to the above effects of the present invention, the optical film as a polarizing plate protective film or the like can meet the demands of thinning, widening and high quality, and a production method of an optical film having high productivity, and a high quality optical film produced by the above method. The polarizing plate and the display device using this optical film can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS It is a flow sheet which shows embodiment of the apparatus which implements the manufacturing method of the optical film by the melt casting film forming method in this invention.
It is explanatory drawing for demonstrating the principle of the atmospheric pressure plasma irradiation apparatus used by the manufacturing method of the optical film of this invention.
It is explanatory drawing for demonstrating the principle of the excimer ultraviolet irradiation device used by the manufacturing method of the optical film of this invention.

EMBODIMENT OF THE INVENTION Next, although embodiment of this invention is described with reference to drawings, this invention is not limited to these.

BRIEF DESCRIPTION OF THE DRAWINGS It is a flow sheet which shows embodiment of the apparatus which implements the manufacturing method of the optical film of this invention by a melt casting film forming method.

This invention is a manufacturing method of the optical film by a melt casting film forming method, The resin melt containing a thermoplastic resin and an additive is cast on the surface of the metal support body 5 which consists of a 1st cooling roll from the casting die 4, and a casting film (web) (10) is carried out in the presence of a gas to be used for the casting step, the step of peeling from the metal support body 5 after the solidification of the casting film 10 by cooling and solidification, It is characterized by having the process of forming a surface treatment film on the surface of a metal support body over the almost full width of a metal support body by an atmospheric pressure plasma irradiation process or an excimer ultraviolet irradiation process.

In FIG. 1, the vapor | steam of an additive and a normal-pressure plasma are formed in the non-passing section of the flexible film of the surface of the metal support body 5 which consists of a 1st cooling roll during film forming (the flexible process and the process of forming a surface treatment film are performed simultaneously). The atmospheric pressure plasma irradiation treatment or the excimer ultraviolet irradiation treatment is applied to the atmospheric pressure plasma irradiation treatment apparatus 21 or the excimer ultraviolet irradiation apparatus 22 over almost the entire width of the metal support 5 in the presence of a gas used for irradiation or excimer ultraviolet irradiation. By performing a high energy irradiation process, a surface treatment film is formed in the surface of the metal support body 5, and a resin melt is cast on the surface of the metal support body 5 after that.

That is, according to the method of this invention, the non-passing section of the web of the surface of the metal support body 5 which consists of a 1st cooling roll online on the surface of the metal support body 5 which consists of a 1st cooling roll so-called online during film forming In the section where the surface of 5) is exposed, the metal support made of the first cooling roll by subjecting the high energy irradiation treatment by the atmospheric pressure plasma irradiation treatment apparatus 21 or the excimer ultraviolet irradiation apparatus 22 in the presence of the vapor of the additive. The surface of (5) is modified, and the resin melt is cast on the surface of the metal support 5 after the modification.

In addition, although not shown, in another embodiment of the manufacturing method of the optical film of this invention, in the manufacturing method of the optical film by a melt casting film forming method, before casting a resin melt containing a thermoplastic resin and an additive, the vapor of an additive is carried out. And the high-energy irradiation treatment by the atmospheric pressure plasma irradiation treatment apparatus 21 or the excimer ultraviolet irradiation apparatus 22 over almost the entire width of the metal support 5 in the presence of a gas used for atmospheric pressure plasma irradiation or excimer ultraviolet irradiation. As a result, a surface treatment film is formed on the surface of the metal support 5, and then the resin melt is cast on the surface of the metal support 5.

That is, according to the method of the other embodiment of this invention, the surface of the metal support body 5 which consists of a 1st cooling roll is substantially full width of the surface of the metal support body 5 which consists of a 1st cooling roll so-called offline before casting a resin melt. It consists of a 1st cooling roll by performing high energy irradiation process by the atmospheric pressure plasma irradiation processing apparatus 21 or the excimer ultraviolet irradiation apparatus 22 in presence of the vapor of an additive and the gas used for an atmospheric pressure plasma irradiation or excimer ultraviolet irradiation over the The surface of the metal support 5 is modified, and the resin melt is cast on the surface of the metal support 5 after the modification.

In this case, the vapor of the additive means the vapor of the plasticizer or ultraviolet absorber mainly contained in the resin melt. The atmospheric pressure plasma irradiation treatment or the excimer ultraviolet irradiation treatment is performed in the presence of the vapor of the additive.

In addition, when the high energy irradiation process is performed by the atmospheric pressure plasma irradiation apparatus 21 or the excimer ultraviolet irradiation apparatus 22 so-called offline before the resin melt melts on the surface of the metal support body 5, for example, A plasticizer or an ultraviolet absorber is introduced into the hot wind generator, and the warm air is blown out by the hot wind generator to warm and volatilize. It is conceivable to perform atmospheric pressure plasma irradiation treatment or excimer ultraviolet irradiation treatment in the presence of vapor of the additive.

In addition, the gas used for an atmospheric pressure plasma irradiation process or an excimer ultraviolet irradiation process means the reactive gas used for this in the case of the atmospheric pressure plasma irradiation apparatus 21, and uses it for the excimer ultraviolet irradiation apparatus 22 in this case. It means purge gas, such as nitrogen gas.

In this invention, atmospheric pressure plasma irradiation or excimer ultraviolet irradiation is performed in presence of both the vapor of an additive and the gas used for an atmospheric pressure plasma irradiation process or an excimer ultraviolet irradiation process.

Therefore, in the case where the atmospheric pressure plasma irradiation treatment or the excimer ultraviolet irradiation treatment is performed online, the position where the atmospheric pressure plasma irradiation treatment or the excimer ultraviolet irradiation treatment is performed is that the resin solution in which the vapor of the additive is present is formed on the surface of the metal support. It is preferable to be in the vicinity of the position which is flexible to.

It is explanatory drawing for demonstrating the structure of the atmospheric pressure plasma irradiation apparatus used for implementation of the manufacturing method of the optical film of this invention.

The atmospheric pressure plasma irradiation apparatus 21 applies a high frequency voltage to the opposite electrodes and discharges them to make the reactive gas into a plasma state, thereby decomposing the additive volatile vapor of the web into carbon dioxide, water, or the like and reforming the web surface. .

Atmospheric pressure plasma is largely divided into two types, and one is called a direct method or a planner method, in which the supply gas is plasma-formed by applying high frequency electric power between electrodes arranged to sandwich the object to be processed. Another method is called a remote method or a downstream method, in which reactive gas is introduced into a plasma through an electrode applied with a high frequency voltage. Any of the above manners can be used in the present invention.

Fig. 2 shows an atmospheric pressure plasma apparatus of the type called the remote system or the downstream system.

In the same figure, (a) and (b) are the counter electrodes of the atmospheric pressure plasma irradiation apparatus 21, (g) is a reactive gas, and (d) is a plasma injection slit to the surface of the metal support body 5 which consists of a 1st cooling roll. It's a gap.

As a simple structure of the atmospheric pressure plasma irradiation apparatus 21, a reactive gas (also referred to as a raw material gas) is introduced and passed between a counter electrode (a) and (b) to which a high frequency voltage is applied, thereby forming a plasma, and comprising a first cooling roll. The surface treatment film is formed by spraying and supplying the surface of the metal support 5.

In this embodiment, it is necessary to adopt the atmospheric pressure plasma irradiation apparatus 21 which can apply such a high power voltage and maintain a uniform glow discharge state.

As such an electrode, it is preferable to coat a dielectric on a metal base material. The dielectric is coated on at least one of the opposite applied electrode and the earth electrode, and more preferably, the dielectric is coated on both the opposite applied and earth electrodes. The dielectric material is preferably an inorganic material having a relative dielectric constant of 6 to 45. Examples of such dielectrics include ceramics such as alumina and silicon nitride or glass lining materials such as silicate glass and borate glass.

In addition, when placing the cellulose-ester film which is a transparent film base material between electrodes, or conveying between electrodes and exposing to plasma, not only makes a transparent electrode base material the roll electrode specification which can contact and convey one electrode, but also makes a dielectric surface By polishing and finishing the surface roughness Rmax (as defined in JIS B 0601) of the electrode to 10 µm or less, the thickness of the dielectric and the gap between the electrodes can be kept constant, and the discharge state can be stabilized, and the heat shrinkage difference and residual stress It is preferable because the durability can be greatly improved by eliminating the distortion and cracks caused by the coating and coating the inorganic dielectric with high precision rather than porousness.

In addition, the clearance gap d between the surface of the metal support 5 made of the jet slit for performing the injection supply of the plasma and the first cooling roll is too close to the atmospheric pressure plasma irradiation apparatus 21 by the curl of the web, and the web is scratched. On the contrary, when it is too far apart, 1-30 mm is preferable, and 2-20 mm is more preferable, since radicals of a plasma do not fully reach and since volatile vapor decomposition of an additive or modification of a web surface cannot fully be carried out.

In addition, various materials, such as nitrogen, oxygen, argon, and helium, can be used for the source gas g, but from the viewpoint of the environment, post-treatment of exhaust, and running cost, nitrogen is preferable. Furthermore, it is more preferable to mix trace amount oxygen with nitrogen. As for the mixing ratio of oxygen, 5 volume% or less is preferable with respect to the volume of source gas.

In addition, the amount of source gas air flow of the atmospheric pressure plasma is preferably 20 to 5000 L / min per plasma width. Furthermore, 40-2500 L / min are more preferable. In addition, it is preferable to provide an exhaust device near the atmospheric pressure plasma irradiation device 21 to exhaust the decomposition gas.

The position where the atmospheric pressure plasma irradiation treatment is performed (the position where the reactive gas g is injected into the metal support) is preferably near the position where the resin solution is softened on the surface of the metal support, in which a large amount of vapor of the additive is present. . Specifically, referring to FIG. 2, when the metal support has a roll shape like the first cooling roll 5, the position P1 at which the atmospheric pressure plasma irradiation treatment is performed and the center point P3 of the first cooling roll 5 are performed. The angle formed by the line L1 at the time of connection, the line L2 at the time of connecting the position P2 at which the resin solution is flexible to the surface of the metal support and the center point P3 of the first cooling roll 5 ( (theta) is preferably 120 ° or less. If it is 120 degrees or less, much vapor of an additive exists and can form a uniform surface treatment film on the surface of a metal support body.

Moreover, as processing conditions of normal temperature plasma processing, it is preferable that the electric power supplied between electrodes is 1W / cm <2> or more and 50W / cm <2> (area of the range which a discharge generate | occur | produces). By setting the treatment conditions in this range, it is preferable at the point that sufficient surface treatment can be performed without causing abnormal discharge such as arc discharge.

FIG. 3: is explanatory drawing for demonstrating the principle of the excimer ultraviolet irradiation device 22 used by the manufacturing method of the optical film of this invention.

In the figure, (u) is an excimer ultraviolet lamp, (r) is a reflector, (p) is a purge gas, and (d) is a gap from the excimer ultraviolet lamp u to the metal support 5 made of the first cooling roll. .

In this embodiment, various ultraviolet irradiation apparatus can be used, Especially wavelength is 250 nm or less is preferable. Under such ultraviolet irradiation, the oxygen contained in the purge gas p generates active oxygen and ozone, decomposes the volatile vapor of the additive with carbon dioxide, carbon dioxide, water, or the like, and consists of a first cooling roll 5. To modify the surface.

In addition, the gap d between the ultraviolet ray lamp u and the metal support 5 made of the first cooling roll is too close to the UV lamp device in contact with the ultraviolet ray lamp device by curl of the web, and if the distance is too far, the ultraviolet light It is preferably about 1 to 20 mm, more preferably 2 to 15 mm, because it is absorbed by oxygen and the decomposition of the volatile vapor of the additive and the modification of the web surface cannot be sufficiently performed. In addition, it is preferable to provide an exhaust device in the vicinity of the ultraviolet irradiation device 22 to exhaust the decomposition gas.

Moreover, it is preferable that the position which performs an excimer ultraviolet irradiation process is near the position where the resin solution in which much vapor of an additive exists is cast on the surface of a metal support body. Specifically, referring to FIG. 3, when the metal support has a roll shape like the first cooling roll 5, the position P1 (center position irradiated with an ultraviolet lamp) and the first cooling roll to perform the excimer ultraviolet irradiation treatment When the line L1 at the time of connecting the center point P3 of (5), the position P2 at which the resin solution is cast on the surface of the metal support body, and the center point P3 of the first cooling roll 5 are connected. The angle θ formed by the line L2 is preferably 120 ° or less. If it is 120 degrees or less, much vapor of an additive exists and can form a uniform surface treatment film on the surface of a metal support body.

Moreover, as processing conditions of an excimer ultraviolet-ray treatment, it is preferable to irradiate the ultraviolet-ray whose main wavelength is 172 nm with the light quantity of 1-3,000mJ / cm <2>. It is preferable at the point which sufficient surface treatment effect is acquired in a short time by making processing conditions into this range.

The method for producing an optical film according to the present invention comprises a step of forming a flexible film by casting a resin melt containing a thermoplastic resin and an additive on a surface of a metal support 5 made of a first cooling roll, and cooling and solidifying the flexible film. Atmospheric pressure plasma irradiation treatment or excimer over the whole width of the metal support body 5 which consists of a 1st cooling roll in the process of peeling from the support body 5, and the presence of the gas used for vapor of an additive and atmospheric pressure plasma irradiation or excimer ultraviolet irradiation. It has a process of forming a surface treatment film in the surface of the metal support body 5 which consists of a 1st cooling roll by performing an ultraviolet irradiation process. In addition, the process of forming a surface treatment film on the surface of the metal support body 5 which consists of a 1st cooling roll may be performed online, or may be performed offline. According to the method of this invention, a plasticizer is applied to the surface of the metal support body 5 which consists of a 1st cooling roll by performing an atmospheric pressure plasma irradiation process or an excimer ultraviolet irradiation process in presence of the vapor of an additive, and the gas used for atmospheric pressure plasma irradiation or excimer ultraviolet irradiation. A very dense surface treatment film is formed that contains a decomposition product of an additive such as a constituent component, and the release property (peelability) of the film from the surface of the metal support 5 is remarkably improved due to the presence of the surface treatment film, resulting in very smooth peelability. Obtained, the variation in the width direction of the peeling position decreases, and the variation in the retardation (Re) value in the film width direction and the longitudinal direction is greatly reduced, thereby making it possible to produce an optical film having optical properties excellent in transparency and planarity. In addition, the production speed can be increased, and the productivity of the film can be improved. A thin film such as a polarizer protective film recently, and it will gwangpokhwa that can meet the demands of quality screen.

In the method for producing an optical film according to the present invention, the plasma irradiation or the ultraviolet irradiation is thus performed in the presence of a gas used for the vapor and atmospheric pressure plasma irradiation treatment of the additive or the excimer ultraviolet irradiation treatment to form a surface treatment film. Therefore, according to the method of the present invention, a very dense surface treatment film having a decomposition product of an additive such as a plasticizer as a constituent is formed on the surface of the metal support 5 made of the first cooling roll, and by the presence of the surface treatment film, 5) The releasability (peelability) of the film from the surface is remarkably improved, and the releasability (peelability) of the film from the surface of the metal support 5 is difficult to deteriorate even in long-term film formation, and the effect persists. Further, even if the components of the surface treatment film are slightly transferred to the film from the surface of the metal support 5, since they are additives originally added to the film, there is little effect on the film properties.

Moreover, according to the manufacturing method of the optical film by this invention, it is preferable that the surface treatment film formed in the surface of the metal support body 5 has the contact angle of 5-40 degrees of the said process film and water.

In addition, although the metal support body 5 consists of a cooling roll in embodiment shown, the metal support body 5 used for the manufacturing method of the optical film of this invention may be another endless belt or drum for film forming.

Moreover, according to the manufacturing method of the optical film by this invention, the minimum amount of increase of peeling force required for peeling the flexible film after cooling from the surface of a metal support body is 0.1-2.0 (at the time of film forming start and 24 hours after film forming. It is preferable to exist in the range of N / m).

According to the optical film manufactured by the manufacturing method of the optical film of this invention, mold release property (peelability) of the film from the metal support body 5 is improved and very smooth peelability is obtained, and the fluctuation of the width direction of a peeling position is reduced. From the point of view, the variation of the retardation (Re) value in the film width direction and the longitudinal direction is greatly reduced in the optical film, and is excellent in transparency and planarity.

Moreover, it is preferable that the dispersion | variation in the transmittance | permeability in the wavelength 600 nm at the time of cross nicol of the optical film manufactured by the manufacturing method of the optical film of this invention exists in the range of 2 * 10 <^-5> -60 * 10 <^-5> (%). . As a result, when assembled to the liquid crystal panel, a uniformly high contrast is obtained in the entire screen.

According to the manufacturing method of the optical film of this invention, the manufacturing method of the high quality optical film which can respond to the request of thinning of film, widening width, and high quality of an optical film as a protective film for polarizing plates, etc. can be provided.

Next, the manufacturing method of the optical film by the melt casting film forming method of this invention is demonstrated in detail.

As shown in Fig. 1, for example, a cellulose ester-based resin dried under hot air, vacuum, or reduced pressure is melted at an extrusion temperature of about 200 to 300 ° C. using an extruder 1, and a leaf disc type filter 2 and the like. Filter to remove foreign substances. In addition, when introducing into the extruder 1 from a supply hopper (not shown), it is preferable to prevent oxidative decomposition and the like under vacuum or reduced pressure or inert gas atmosphere.

When additives, such as a plasticizer, are not mixed beforehand, you may carry out in the middle of an extruder. In order to add uniformly, it is preferable to use mixing apparatuses, such as the static mixer 3 and the like.

It is preferable to mix additives, such as resin, such as a cellulose resin, and the stabilizer added as needed, before melting. The mixing may be performed by a mixer or the like, or may be mixed in a resin preparation process such as a cellulose resin as described above. When using a mixer, a general mixer, such as a V-type mixer, a conical screw type mixer, and a horizontal cylindrical mixer, can be used.

After mixing the film constituent materials as described above, the mixture may be directly melted and formed into a film by using the extruder 1, but after pelletizing the film constituent material, the pellet is melted by the extruder 1 to form a film. You may also do so. In addition, in the case where the film constituent material includes a plurality of materials having different melting points, a so-called half-sweet semi-melt is first produced at a temperature at which only the material having a low melting point melts, and the semi-melt is introduced into the extruder 1. It is also possible to make a film. When the film constituent material contains a material that is easy to thermally decompose, a method of directly forming a film without producing pellets for the purpose of reducing the number of melting, or a method of forming a semi-melt material having a bake pastry shape as described above is preferable.

Although the extruder 1 can use the various extruders available on the market, melt-kneading extruder is preferable and may be a single screw extruder or a twin screw extruder. In the case of directly forming a film without producing pellets from a film constituent material, it is preferable to use a twin screw extruder because appropriate kneading degree is required. By changing to a kneading screw, proper kneading can be obtained, and thus it can be used. As a film constituent material, when using the pellets or the semi-molten melt of the pastry shape once, even a single screw extruder or a twin screw extruder can be used.

In the extruder 1 and the extruded cooling step, the concentration of oxygen is preferably reduced by replacing with an inert gas such as nitrogen gas or by reducing the pressure.

The melting temperature of the film constituent material in the extruder 1 varies depending on the viscosity of the film constituent material, the discharge amount, the thickness of the sheet to be produced, and the like, but in general, Tg or more relative to the glass transition temperature Tg of the film (resin mixture). , Tg + 100 ° C. or lower, preferably Tg + 10 ° C. or higher and Tg + 90 ° C. or lower.

The melt viscosity at the time of extrusion is 10-100000 poise, Preferably it is 100-10000 poise. In addition, the shorter residence time of the film constituent material in the extruder 1 is preferably within 5 minutes, preferably within 3 minutes, and more preferably within 2 minutes. Although the residence time depends on the type of extruder 1 and the conditions to extrude, it can shorten by adjusting supply amount of material, L / D, screw rotation speed, the depth of the groove of a screw, etc.

The shape, rotation speed, etc. of the screw of the extruder 1 are suitably selected according to the viscosity, discharge amount, etc. of a film component material. In the present embodiment, the shear rate in the extruder 1 is 1 / second to 10000 / second, preferably 5 / second to 1000 / second, more preferably 10 / second to 100 / second. As the extruder 1, the extruder generally marketed as a plastic molding machine can be used.

The film component material extruded from the extruder 1 is sent to the casting die 4, and is extruded from the casting die 4 into a film form.

The melt discharged from the extruder 1 is supplied to the casting die 4. The casting die 4 is not particularly limited as long as it is used for producing a sheet or a film. As the material of the flexible die 4, hard chromium, chromium carbide, chromium nitride, titanium carbide, titanium carbonitride, titanium nitride, super steel, ceramic (tungsten carbide, aluminum oxide, chromium oxide), etc. are sprayed or plated, and the surface treatment is performed. Buffing, lapping using # 1000 or later grindstones, planar cutting using diamond grindstones # 1000 or greater (cutting direction perpendicular to resin flow direction), electropolishing, electrolytic compound polishing, etc. Etc. can be mentioned.

The preferred material of the lip portion of the flexible die 4 is the same as that of the flexible die 4. Moreover, 0.5S or less is preferable and, as for the surface precision of a lip | rip part, 0.2S or less is more preferable.

In the method for producing an optical film of the present invention, as described above, the surface of the metal support body 5 made of the first cooling roll is formed at a predetermined position on the surface of the metal support body 5 before casting the resin melt or during the film formation. In the non-passing section of the web on the surface of the support 5 (section in which the surface of the metal support 5 is exposed during film formation), atmospheric pressure plasma irradiation in the presence of a gas used for vapor and atmospheric pressure plasma irradiation or excimer ultraviolet radiation of the additive. The surface of the metal support 5 is modified by high-energy surface treatment by the apparatus 21 or the excimer ultraviolet irradiation device 22, and the resin melt is cast on the surface of the metal support 5 after modification.

That is, in the method for producing an optical film according to the present invention, the vapor of the additive is formed at a predetermined position on the surface of the metal support 5 so-called offline before the resin melt is cast, before the resin melt is cast. And modifying the surface of the metal support 5 by performing a high energy surface treatment by the atmospheric pressure plasma irradiation apparatus 21 or the excimer ultraviolet irradiation apparatus 22 in the presence of a gas used for atmospheric pressure plasma irradiation or excimer ultraviolet irradiation. Alternatively, during film formation, the non-passing section of the web on the surface of the metal support 5 online (section where the surface of the metal support 5 is exposed during film formation) is used for vapor and atmospheric plasma irradiation or excimer ultraviolet irradiation of the additive. High energy surface by atmospheric pressure plasma irradiation apparatus 21 or excimer ultraviolet irradiation apparatus 22 in the presence of the gas By carrying out the re is to modify the surface of a metal support (5), the flexible resin melt on the metal supporting body 5 after the surface modification.

In this embodiment, after mixing the film material containing resin, such as a cellulose ester resin, and obtaining a resin mixture, it uses the extruder 1 on the 1st cooling roll (metal support) 5 from the casting die 4 Melt extrusion is carried out, and circumscribed to the 1st cooling roll 5, the film-like melt is pressurized by the touch roll 6 to the surface of the 1st cooling roll 5 by predetermined | prescribed pressure. In addition, the three cooling rolls of the 2nd cooling roll 7 and the 3rd cooling roll 8 are externally circumscribed in order, and it solidifies by cooling, and peels with the peeling roll 9. The peeled web 10 is stretched in the width direction by holding both ends of the web 10 by the tenter 11, and after that, the stretched film is wound up by the winding machine 12. FIG.

In this embodiment, the temperature of the 1st cooling roll 5 is set to below the glass transition temperature (Tg) of a resin mixture, or more than melting | fusing point of an additive.

Moreover, in the manufacturing method of the optical film of this embodiment, ratio (S2 / S1) of the circumferential speed S1 of the 1st cooling roll 5 and the circumferential speed S2 of the 2nd cooling roll 7 is 1.001 thru | or. It is preferable to set it to 1.05.

The touch roll 6 is a rotating body for the purpose of clamping the film against the film in the direction of the first cooling roll 5 from the side opposite to the first cooling roll 5.

It is preferable that the surface of the touch roll 6 is metal, and thickness is 1 mm-10 mm. Preferably it is 2 mm-6 mm. The surface of the touch roll 6 is subjected to treatment such as chromium plating, and the surface roughness is preferably 0.2 S or less. The smoother the roll surface, the smoother the surface of the film obtained can be.

The metal material of the surface of the touch roll 6 needs to be smooth, moderate elasticity, and durable. Carbon steel, stainless steel, titanium, nickel produced by the electroforming method, etc. can be used preferably. Moreover, in order to improve the hardness of the surface or to improve peelability with resin, it is preferable to perform surface treatment of hard chrome plating, nickel plating, amorphous chromium plating, etc., ceramic spraying, etc. It is preferable to grind | surface the surface-processed surface further and to make it the surface roughness mentioned above.

The touch roll 6 has the double structure of a metal outer cylinder and an inner cylinder, and is a structure of the double cylinder which has a space so that a cooling fluid can flow between them.

It is preferable that an inner cylinder is a metal inner cylinder with light weight and rigidity, such as carbon steel, stainless steel, aluminum, and titanium. By having rigidity in an inner cylinder, rotational rotation of a roll can be suppressed. Sufficient rigidity is obtained by making the thickness of an inner cylinder into 2 to 10 times the outer cylinder. The inner cylinder may further be coated with a resin elastic material such as silicone or fluororubber.

The structure of the space through which the cooling fluid flows should be one capable of controlling the temperature of the roll surface uniformly. For example, the temperature distribution on the roll surface can be increased by allowing the circulation and the reverse flow to flow alternately or in a spiral shape in the width direction. Small temperature control is possible. There is no restriction | limiting in particular in a cooling fluid, Water or oil can be used according to the temperature range to be used.

In this embodiment, the touch roll 6 which is a 2nd rotating body is set to the drum type whose outer diameter of a center part is larger than the outer diameter of both ends. Although it is common to press both ends of a touch roll to a film by a press means, in this case, since a touch roll bends, there exists a phenomenon which is pressed strongly toward an edge part. By making a roll into a drum type, highly uniform pressurization is attained.

It is preferable that the diameter of the touch roll 6 which is a 2nd rotating body is 200 mm-500 mm. The effective width of the touch roll 6 needs to be wider than the film width clamped. The difference between the radius of the center part of the touch roll 6 and the radius of the edge part (hereinafter, referred to as a crowning amount) can prevent nonuniformity such as streaks generated in the center part of the film. The amount of crowning is preferably in the range of 50 to 300 µm.

The 1st cooling roll 5 and the touch roll 6 are installed in the position opposite to the plane of a film so that the film may be clamped. The 1st cooling roll 5 and the touch roll 6 may contact a film with surface, or may contact with a line.

In the manufacturing method of the optical film by this embodiment, the conditions of melt extrusion can be performed similarly to the conditions used for thermoplastic resins, such as another polyester. It is preferable to dry material beforehand. It is preferable to dry the moisture to 1000 ppm or less, preferably 200 ppm or less with a vacuum or reduced pressure drier, a dehumidifying hot air drier or the like.

In this embodiment, the melted resin mixture is extruded from the casting die 4 provided in the extruder to the film-like resin, and the extruded film-like resin adheres to at least two rotating bodies, and it shape | molds and takes out.

At this time, it is preferable to pressurize the film to the 1st cooling roll 5 by the press means which consists of touch rolls 6. The linear pressure at which the touch roll 6 pressurizes a film at this time can be adjusted with a hydraulic piston etc., Preferably it is 0.1-100 N / mm, More preferably, it is 1-50 N / mm.

In addition, the 1st cooling roll 5 or the touch roll 6 can also make the diameter of both ends of a roll thin, or have a flexible roll surface, in order to raise the uniformity of adhesion | attachment with a film.

When the part from the opening part (lip) of the casting die 4 to the 1st cooling roll 5 is pressure-reduced to 70 kPa or less, the correction effect of the said die line will express more largely. Preferably, the reduced pressure is 50 kPa or more and 70 kPa or less. There is no restriction | limiting in particular as a method of maintaining the pressure of the part from the lip of the casting die 4 to the 1st cooling roll 5 to 70 kPa or less, but the pressure reduction member covers the roll periphery from the casting die 4, etc. There is a way. At this time, it is preferable that the suction device is subjected to treatment such as heating with a heater so that the device itself does not become a place where the sublimation is attached. If the suction pressure is too small, the sublimation cannot be sucked effectively, so it is necessary to set it to a suitable suction pressure.

In this embodiment, the film-shaped cellulose ester-type resin of a molten state is contact | adhered to the 1st cooling roll 5, the 2nd cooling roll 7, and the 3rd cooling roll 8 sequentially from the T die 4, It cools and solidifies, conveying, and obtains the web 10 of cellulose ester-type resin.

In embodiment of this invention shown in FIG. 1, the cooling solidified web 10 peeled from the 3rd cooling roll 8 with the peeling roll 9 is extended | stretched with the tenter 11. As shown in FIG. By this stretching, the molecules in the film are oriented.

The apparatus for cooling the film (resin mixture) extruded from the casting die 4 is not limited to a roll, but may be a drum, a belt, or the like.

It is preferable that the film 10 peeled from the above-mentioned cooling roll 5 is longitudinally stretched once or in multiple stages by the tenter 11 via heating apparatuses, such as one or several roll groups and / or an infrared heater. Do. At this time, when the glass transition temperature of a film is made into Tg, it is preferable to heat in the range of Tg-50 degreeC to Tg + 80 degreeC, and to extend | stretch to a conveyance direction.

Next, it is preferable to transversely stretch the film extended | stretched in a conveyance direction within the temperature range of Tg-50 degreeC-Tg + 80 degreeC, and to heat-fix continuously.

The tenter 11 may be transversely stretched. In this case, if the transverse stretching is performed while the temperature difference is gradually raised in a range of 1 to 50 ° C. in the stretching region divided into two or more, the thickness in the width direction and the optical distribution are preferable. Do.

Although Tg differs according to a film structure material, Tg can be controlled by making the ratio of the material type which comprises a film, and the material which comprises a film different. When producing retardation film as an optical film, Tg is 120 degreeC or more, Preferably it is 135 degreeC or more. In the liquid crystal display device, in the display state of an image, the temperature environment of the said film changes by the temperature rise of the apparatus itself, for example, the temperature rise derived from a light source. At this time, when Tg of the said film is lower than the use environment temperature of the said film, a big change will be provided to the retardation value resulting from the orientation state of the molecule fixed inside the film by extending | stretching, and the dimensional shape as a film. If the Tg of the film is too high, the temperature increases when filming the film constituent material, and thus the energy consumption for heating increases, and further, decomposition of the material itself and coloring by the film when filming may occur, so that Tg is 250. C or less is preferable.

In addition, a well-known heat setting process, cooling, and a relaxation process may be performed to an extending process, and what is necessary is just to adjust suitably so that it may have the characteristic requested | required of the target optical film.

When manufacturing a retardation film, in order to provide the function and physical property which are necessary for the viewing angle enlargement of a liquid crystal display device, the said extending process and heat fixing process are selected suitably and are performed. That is, when manufacturing a retardation film as an optical film and combining the function of a polarizing plate protective film, although refractive index control needs to be performed, the refractive index control can be performed by an extending | stretching operation, and the extending | stretching operation is a preferable method. to be. Hereinafter, the stretching method will be described.

In the stretching step of the retardation film, the retardation Ro and Rt required can be controlled by stretching in 1.0 to 3.0 times in one direction of the cellulose resin and 1.01 to 3.5 times in the direction orthogonal to it in the film plane. Here, Ro represents in-plane retardation, multiplies the difference between the refractive index in the in-plane longitudinal direction MD and the refractive index in the width direction TD, and Rt represents the thickness direction retardation, and represents the in-plane refractive index (length direction). (MD), average of width direction (TD)] and the difference of the refractive index of the thickness direction multiplied by thickness.

Stretching can be performed sequentially or simultaneously with respect to the longitudinal direction (flexibility and conveyance direction) of a film, and the direction orthogonal to it in a film plane, ie, the width direction, for example. At this time, when the draw ratio in at least one direction is too small, a sufficient phase difference is not obtained, and when too large, stretching is difficult and film breakage may occur.

Stretching in the biaxial direction perpendicular to each other is an effective method for bringing the refractive indices nx, ny, and nz of the film into a predetermined range. Here, nx is a refractive index in the length (MD) direction, ny is a refractive index in the width (TD) direction, nz is a refractive index in the thickness direction.

For example, in the case of stretching in the melt casting direction, if the shrinkage in the width direction is too large, the value of nz becomes too large. In this case, it can improve by suppressing the width shrinkage of a film or extending | stretching also in the width direction. When extending | stretching in the width direction, distribution may generate | occur | produce in the refractive index in the width direction. This distribution may appear when a tenter method is used, and it is a phenomenon which arises when shrinkage force generate | occur | produces in a film center part and the edge part is fixed by extending | stretching a film to the width direction, and is considered to be called what is called a boeing phenomenon. Also in this case, by extending | stretching to a casting | flow_spread direction, a bowing phenomenon can be suppressed and distribution of the phase difference of the width direction can be reduced.

By extending | stretching in the biaxial direction orthogonal to each other, the film thickness variation of the film obtained can be reduced. When the film thickness fluctuation of a retardation film is too large, it becomes a nonuniformity of retardation, and when used for a liquid crystal display, nonuniformity, such as coloring, may become a problem.

It is preferable to make the film thickness variation of a cellulose resin film into the range of +/- 3%, and also +/- 1%. For the above purposes, a method of stretching in the biaxial directions perpendicular to each other is effective, and the stretching ratios in the biaxial directions perpendicular to each other are finally 1.0 to 3.0 times in the flexible direction and 1.01 to 3.5 times in the width direction, respectively. It is preferable to set it as this, and it is more preferable in order to obtain the retardation value required to perform in the range of 1.01-2.5 times in a casting | flow_spread direction, and 1.05-3.0 times in the width direction.

After the stretching of the web 10 by the above tenter, the end of the obtained web (film) is slit and cut into a width to be a product by a slitter, and then knurled by a knurling processing device comprising an emboss ring and a back roll. Processing (embossing) is performed at both ends of the film, and is wound up by the winding machine 13 to prevent adhesion or scratches in the optical film (original winding body). The method of knurling processing can process a metal ring which has a pattern of unevenness | corrugation in the side by heating and pressurization. In addition, since the holding part of the clip of film both ends is deformed normally and cannot be used as a film product, it is cut out and recycled as a raw material.

The thermoplastic resin used for the manufacturing method of the optical film of this invention will not be specifically limited if it can form into a film by the melt casting film forming method. For example, a cellulose ester, polycarbonate, an alicyclic structure containing polymer, polyvinyl alcohol, polyamide, polyimide, polyester, etc. are mentioned. Especially, a cellulose ester and an alicyclic structure containing polymer are preferable at the point with a small photoelastic coefficient, and an alicyclic structure containing polymer is especially preferable at the point where water absorption is small.

As cellulose ester, cellulose acetate propionate, cellulose acetate butyrate, and cellulose acetate propionate butyrate are preferable. Since the substitution degree of the acetyl group of the said cellulose ester is at least 1.5 or more, since the dimensional stability of the film obtained is excellent, it is preferable. As a measuring method of substitution degree of the acyl group of a cellulose ester, it can carry out according to D-817-91 of ASTM. Since the molecular weight of a cellulose ester is 50,000-300,000, especially 60,000-200,000 as a number average molecular weight, since the mechanical strength of the film obtained can be strengthened, it is preferable.

An alicyclic structure containing polymer is a polymer which has an alicyclic structure in a repeating unit, and an alicyclic structure may be any of a main chain and a side chain. Examples of the alicyclic structure include a cycloalkane structure and a cycloalkene structure, but the cycloalkane structure is preferable from the viewpoint of excellent thermal stability.

The alicyclic structure-containing polymer is a monomer containing a monomer having a norbornene ring structure, a monocyclic olefin, a cyclic conjugated diene, a vinyl aromatic compound, a vinyl alicyclic hydrocarbon compound, or the like, and known monomers such as metathesis ring-opening polymerization or addition polymerization. It can superpose | polymerize by a polymerization method and can obtain by hydrogenating a carbon-carbon unsaturated bond as needed.

The alicyclic structure-containing polymer used in the present invention has a weight average molecular weight (Mw) in terms of polyisoprene or polystyrene measured by gel permeation chromatography of a cyclohexane solution (toluene solution if the polymer does not dissolve). It is preferable that it is and it is more preferable that it is 30,000-45,000. It is preferable that it is 1.2-3.5, and, as for molecular weight distribution (Mw / Mn), it is more preferable that it is 1.5-3.0. Moreover, it is preferable that glass transition temperature (Tg) is 80-170 degreeC. By setting the properties of the alicyclic structure-containing polymer in the above range, good heat resistance and molding processability can be obtained.

Although polyester is not specifically limited, It is preferable to make a dicarboxylic acid component and a diol component the main structural component.

As dicarboxylic acid component which is a main component, terephthalic acid, isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, diphenyl sulfone dicarboxylic acid, diphenyl ether dicarboxylic acid Acid, diphenylethanedicarboxylic acid, cyclohexanedicarboxylic acid, diphenyldicarboxylic acid, diphenylthioetherdicarboxylic acid, diphenylketonedicarboxylic acid, phenylindandicarboxylic acid, etc. Can be mentioned. Moreover, as a diol component, ethylene glycol, propylene glycol, tetramethylene glycol, cyclohexane dimethanol, 2, 2-bis (4-hydroxyphenyl) propane, 2, 2-bis (4-hydroxyethoxyphenyl) propane, Bis (4-hydroxyphenyl) sulfone, bisphenol fluorene dihydroxy ethyl ether, diethylene glycol, neopentyl glycol, hydroquinone, cyclohexanediol, etc. are mentioned.

Among polyesters having these as main constituents, ethylene glycol and / or 1 as terephthalic acid and / or 2,6-naphthalenedicarboxylic acid and diol component from the viewpoints of transparency, mechanical strength, dimensional stability, etc. Preference is given to polyesters having, 4-cyclohexanedimethanol as the main constituent. Among them, polyesters having polyethylene terephthalate or polyethylene-2,6-naphthalenedicarboxylate as main constituents, co-polyesters composed of terephthalic acid, 2,6-naphthalenedicarboxylic acid and ethylene glycol, and these polyesters Preference is given to polyesters which have a mixture of two or more of them as the main constituent. When polyethylene-2,6-naphthalenedicarboxylate is contained 70 weight% or more with respect to polyester, the polyester film highly excellent in transparency, mechanical strength, dimensional stability, etc. is obtained.

As long as the polyester which comprises the polyester film of this invention is a range which does not impair the effect of this invention, another copolymerization component may be copolymerized and other polyester may be mixed. As these examples, the dicarboxylic acid component, diol component, or polyester which consists of these mentioned before is mentioned.

Moreover, in order to improve the heat resistance of the polyester film of this invention, the compound which has a bisphenol type compound, a naphthalene ring, or a cyclohexane ring can be copolymerized. As these copolymerization ratios, 1-20 mol% is preferable based on the bifunctional dicarboxylic acid which comprises polyester. In addition, two or more types of compatible polymers may be blended and melt kneading described later.

Hereinafter, although especially a cellulose ester is demonstrated in detail to an example, this invention is not limited by this.

When cellulose ester is formed into a film by melt casting method, cellulose ester usually has acid, such as alkylcarboxylic acid and sulfuric acid, remaining in the cellulose ester during its production process. It is preferable to remove the acid to 50 ppm or less in advance, since deterioration occurs and optical properties and mechanical properties such as haze, transmittance, and retardation deteriorate.

Melt casting in the present invention is defined as melt casting by melting the cellulose ester to a temperature exhibiting fluidity without using a solvent and then casting the fluid cellulose ester after that. The shaping | molding method which heat-melts can be classified in more detail into a melt extrusion molding method, a press molding method, an inflation method, an injection molding method, a blow molding method, an extending molding method, etc. Among these, in order to obtain the optical film which is excellent in mechanical strength, surface precision, etc., melt extrusion method is excellent. After the film constituent material is heated to express its fluidity, the cellulose ester film of the present invention is used as a melt casting film forming method by forming a film by casting on a rotary drive metal endless belt or a rotary drive metal drum (metal support) from a casting die. It is included in the manufacturing method of the.

(Cellulose ester)

The cellulose ester used by this invention is the said single or mixed acid ester of cellulose containing at least any one structure from a fatty acid acyl group and a substituted or unsubstituted aromatic acyl group.

In the aromatic acyl group, when the aromatic ring is a benzene ring, examples of the substituent of the benzene ring are halogen atoms, cyano, alkyl groups, alkoxy groups, aryl groups, aryloxy groups, acyl groups, carbonamide groups, sulfonamide groups, ureido groups, Aralkyl group, nitro, alkoxycarbonyl group, aryloxycarbonyl group, aralkyloxycarbonyl group, carbamoyl group, sulfamoyl group, acyloxy group, alkenyl group, alkynyl group, alkylsulfonyl group, arylsulfonyl group, alkyloxysulfonyl group, aryl Oxysulfonyl group, alkylsulfonyloxy group and aryloxysulfonyl group, -SR, -NH-CO-OR, -PH-R, -P (-R) ₂ , -PH-OR, -P (-R) (-OR), -P (-OR) ₂ , -PH (= O) -RP (= O) (-R) ₂ , -PH (= O) -OR, -P (= O) (-R) (-OR), -P (= O) (-OR) ₂ , -O-PH (= O) -R, -OP (= O) (-R) ₂ -O-PH (= O) -OR, -OP (= O) (-R) (-OR), -OP (= O) (-OR) ₂ , -NH-PH (= O) -R, -NH-P (= O) (-R) (-OR), -NH-P (= O) (-OR) ₂ , -SiH ₂ -R, -SiH (-R) ₂ , -Si (-R) ₃ , -O-SiH ₂ -R,- O-SiH (-R) ₂ and -O-Si (-R) ₃ are included. R is an aliphatic group, an aromatic group or a heterocyclic group. The number of substituents is preferably 1 to 5, more preferably 1 to 4, still more preferably 1 to 3, and most preferably one or two. As the substituent, a halogen atom, cyano, alkyl group, alkoxy group, aryl group, aryloxy group, acyl group, carbonamide group, sulfonamide group and ureido group are preferable, and halogen atom, cyano, alkyl group, alkoxy group, aryl An oxy group, an acyl group, and a carbonamide group are more preferable, A halogen atom, a cyano, an alkyl group, an alkoxy group, and an aryloxy group are more preferable, A halogen atom, an alkyl group, and an alkoxy group are the most preferable.

The halogen atom includes a fluorine atom, a chlorine atom, a bromine atom and an iodine atom. The alkyl group may have a cyclic structure or branch. It is preferable that carbon number of an alkyl group is 1-20, It is more preferable that it is 1-12, It is further more preferable that it is 1-6, It is most preferable that it is 1-4. Examples of alkyl groups include methyl, ethyl, propyl, isopropyl, butyl, t-butyl, hexyl, cyclohexyl, octyl and 2-ethylhexyl. The alkoxy group may have a cyclic structure or branch. It is preferable that carbon number of an alkoxy group is 1-20, It is more preferable that it is 1-12, It is further more preferable that it is 1-6, It is most preferable that it is 1-4. The alkoxy group may be substituted with another alkoxy group. Examples of the alkoxy group include methoxy, ethoxy, 2-methoxyethoxy, 2-methoxy-2-ethoxyethoxy, butyloxy, hexyloxy and octyloxy.

It is preferable that it is 6-20, and, as for the carbon atom number of the said aryl group, it is more preferable that it is 6-12. Examples of aryl groups include phenyl and naphthyl. It is preferable that it is 6-20, and, as for the carbon atom number of the said aryloxy group, it is more preferable that it is 6-12. Examples of aryloxy groups include phenoxy and naphthoxy. It is preferable that it is 1-20, and, as for the carbon atom number of the said acyl group, it is more preferable that it is 1-12. Examples of acyl groups include formyl, acetyl and benzoyl. It is preferable that it is 1-20, and, as for the carbon atom number of the said carbonamide group, it is more preferable that it is 1-12. Examples of carbonamide groups include acetamide and benzamide. It is preferable that it is 1-20, and, as for the carbon atom number of the said sulfonamide group, it is more preferable that it is 1-12. Examples of sulfonamide groups include methanesulfonamide, benzenesulfonamide and p-toluenesulfonamide. It is preferable that it is 1-20, and, as for the carbon number of the said ureido group, it is more preferable that it is 1-12. Examples of ureido groups include (unsubstituted) ureidos.

It is preferable that it is 7-20, and, as for the carbon atom number of the said aralkyl group, it is more preferable that it is 7-12. Examples of aralkyl groups include benzyl, phenethyl and naphthylmethyl. It is preferable that it is 1-20, and, as for the carbon atom number of the said alkoxycarbonyl group, it is more preferable that it is 2-12. Examples of the alkoxycarbonyl group include methoxycarbonyl. It is preferable that it is 7-20, and, as for the carbon atom number of the said aryloxycarbonyl group, it is more preferable that it is 7-12. Examples of the aryloxycarbonyl group include phenoxycarbonyl. It is preferable that it is 8-20, and, as for the carbon atom number of the said aralkyloxycarbonyl group, it is more preferable that it is 8-12. Examples of the aralkyloxycarbonyl group include benzyloxycarbonyl. It is preferable that it is 1-20, and, as for the carbon number of the said carbamoyl group, it is more preferable that it is 1-12. Examples of carbamoyl groups include (unsubstituted) carbamoyl and N-methylcarbamoyl. It is preferable that it is 20 or less, and, as for the carbon atom number of the said sulfamoyl group, it is more preferable that it is 12 or less. Examples of sulfamoyl groups include (unsubstituted) sulfamoyl and N-methylsulfamoyl. It is preferable that it is 1-20, and, as for the carbon number of the said acyloxy group, it is more preferable that it is 2-12. Examples of acyloxy groups include acetoxy and benzoyloxy.

It is preferable that it is 2-20, and, as for the carbon number of the said alkenyl group, it is more preferable that it is 2-12. Examples of alkenyl groups include vinyl, allyl and isopropenyl. It is preferable that it is 2-20, and, as for the carbon number of the said alkynyl group, it is more preferable that it is 2-12. Examples of alkynyl groups include thienyl. It is preferable that it is 1-20, and, as for the carbon atom number of the said alkylsulfonyl group, it is more preferable that it is 1-12. It is preferable that it is 6-20, and, as for the carbon atom number of the said arylsulfonyl group, it is more preferable that it is 6-12. It is preferable that it is 1-20, and, as for the number of carbon atoms of the said alkyloxysulfonyl group, it is more preferable that it is 1-12. It is preferable that it is 6-20, and, as for the carbon atom number of the said aryloxysulfonyl group, it is more preferable that it is 6-12. It is preferable that it is 1-20, and, as for the number of carbon atoms of the said alkylsulfonyloxy group, it is more preferable that it is 1-12. It is preferable that it is 6-20, and, as for the carbon atom number of the said aryloxysulfonyl group, it is more preferable that it is 6-12.

In the cellulose ester of the present invention, when the hydrogen atom of the hydroxyl group portion of the cellulose is a fatty acid ester with an aliphatic acyl group, the aliphatic acyl group has 2 to 20 carbon atoms, specifically acetyl, propionyl, butyryl, isobutyryl, Valeryl, pivaloyl, hexanoyl, octanoyl, lauroyl, stearoyl and the like.

In this invention, the said aliphatic acyl group is the meaning including what has a substituent further, As a substituent, what was illustrated as a substituent of a benzene ring when an aromatic ring is a benzene ring in the aromatic acyl group mentioned above is mentioned.

In addition, when the esterified substituent of the said cellulose ester is an aromatic ring, the number of substituents X substituted by the aromatic ring is 0 or 1-5, Preferably it is 1-3, Especially preferably, 1 or 2 is preferable. In addition, when the number of substituents substituted in the aromatic ring is two or more, they may be the same or different from each other, or they may be linked to each other to form a condensed polycyclic compound (e.g., naphthalene, indene, indane, phenanthrene, quinoline, isoquinoline, chrome, chrome) Phthalazine, acridine, indole, indolin, etc.) may be formed.

In the said cellulose ester, what has a structure which has a structure selected from at least 1 sort (s) of substituted or unsubstituted aliphatic acyl group and substituted or unsubstituted aromatic acyl group is used as a structure used for the cellulose ester which concerns on this invention, and these are the cellulose alone Or mixed acid ester may be used, and 2 or more types of cellulose ester may be mixed and used for it.

The cellulose ester according to the present invention is preferably at least one selected from cellulose acetate, cellulose propionate, cellulose butyrate, cellulose acetate propionate, cellulose acetate butyrate, cellulose acetate phthalate and cellulose phthalate.

As a degree of substitution of the mixed fatty acid ester, more preferable cellulose acetate propionate or lower fatty acid ester of cellulose acetate butyrate has an acyl group having 2 to 4 carbon atoms as a substituent, the degree of substitution of the acetyl group is X, and the propionyl group Or it is a cellulose resin containing the cellulose ester which satisfy | fills the following formula (I) and (II) simultaneously when the substitution degree of a butyryl group is Y. In addition, substitution degree of an acetyl group and substitution degree of another acyl group are calculated | required by ASTM-D817-96.

<Equation I>

2.5≤X + Y≤2.9

<Equation II>

0.1≤X≤2.0

Among them, in particular, cellulose acetate propionate is preferably used, and among them, 1.0 ≦ X ≦ 2.5 and preferably 0.5 ≦ Y ≦ 2.5. You may blend the cellulose ester from which the substitution degree of an acyl group differs, and may fall in the said range as an optical film whole. The part which is not substituted by the said acyl group exists normally as a hydroxyl group. These can be synthesized by a known method. The measuring method of substitution degree of an acetyl group can be measured according to ASTM-D817-96.

The number average molecular weight of the cellulose ester used for the optical film of this invention is preferable because the range of 60000-300000 is the mechanical strength of the film obtained. Moreover, 70000-200000 are preferable.

Further, the cellulose ester used in the present invention is preferably used having a weight average molecular weight (Mw) / number average molecular weight (Mn) ratio of 1.5 to 5.5, particularly preferably 2.0 to 5.0, more preferably 2.5 to 5.0 More preferably, the cellulose ester of 3.0-5.0 is used preferably.

The measuring method of a weight average molecular weight can be based on the following method.

(Molecular weight measurement method)

The molecular weight is measured by high performance liquid chromatography [gel permeation chromatography (GPC)].

Measurement conditions are as follows.

Device: HLC-8220 GPC (Solder)

Column: TSK-SUPER HM-M (φ6.0 mm × 150 mm)

      TSK-Guardcolumn H-H (φ4.6 mm x 35 mm)

Solvent: Tetrahydrofuran

Flow rate: 0.6ml / min

Temperature: 40 ℃

Sample concentration: 0.1% by mass

Calibration curve: Standard polystyrene STK standard polystyrene (manufactured by Tosoh Corp.) Mw = 1000000 to 500 using a calibration curve with 13 samples. 13 samples are used at substantially equal intervals.

Although the raw material cellulose of the cellulose ester used by this invention may be a wood pulp, a cotton linter, and a wood pulp may be a conifer or a hardwood, More conifers are more preferable. From the point of peelability at the time of film forming, a cotton printer is used preferably. The cellulose esters made from these can be appropriately mixed or used alone.

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

In addition, the intrinsic viscosity of the cellulose resin is preferably 1.5 to 1.75 g / cm 3, and more preferably 1.53 to 1.63.

Moreover, it is preferable that the cellulose ester used by this invention has few bright point foreign substances at the time of using a film. A bright spot foreign material means that two polarizing plates are orthogonally arranged (cross nicol), a cellulose ester film is disposed therebetween, light is emitted from the light source from one side, and light from the light source is leaked when the cellulose ester film is observed from the other side. Say something that looks like. At this time, it is preferable that the polarizing plate used for evaluation is comprised by the protective film without a bright spot foreign material, and the thing using the glass plate for the protection of a polarizer is used preferably. The bright point foreign matter is considered to be one of the causes of the microacetization or the low acetylated cellulose contained in the cellulose ester, and the use of a cellulose ester having a small amount of the bright point foreign matter (using a cellulose ester having a small dispersibility of substitution degree), It is also possible to remove the bright point foreign matter through the filtration process in the same manner as the solution state at least once in the process of filtering the melted cellulose ester or in the process of synthesizing the cellulose ester or obtaining the precipitate. Since molten resin has a high viscosity, the latter method is more efficient.

The thinner the film thickness, the lower the number of bright spot foreign matters per unit area, and the smaller the content of cellulose ester contained in the film, the smaller the bright spot foreign matters. It is preferable that it is 2 cm <2> or less, Moreover, it is preferable that it is 100 pieces / cm <2> or less, It is preferable that it is 50 pieces / cm <2> or less, It is preferable that it is 30 pieces / cm <2> or less, It is preferable that it is 10 pieces / cm <2> or less, but it is most preferable that there is nothing. Moreover, it is preferable that it is 200 pieces / cm <2> or less also about the bright point of 0.005-0.01mm or less, It is preferable that it is 100 pieces / cm <2> or less, It is preferable that it is 50 pieces / cm <2> or less, It is preferable that it is 30 pieces / cm <2> or less, It is 10 pieces It is preferable that it is / cm <2> or less, but what is none is most preferable.

In the case where the bright spot foreign matter is removed by melt filtration, it is preferable that the removal efficiency of the bright spot foreign matter is high by filtering the composition in which the plasticizer, the deterioration inhibitor, the antioxidant and the like are added and mixed, rather than filtering the melted cellulose ester alone. Of course, you may melt | dissolve in a solvent at the time of the synthesis | combination of a cellulose ester, and may reduce by filtration. What mixed suitably also an ultraviolet absorber and other additives can be filtered. It is preferable that the viscosity of the melt containing a cellulose ester is filtered at 10000P or less, More preferably, it is 5000P or less, It is more preferable that it is 1000P or less, It is further more preferable that it is 500P or less. As a filter medium, conventionally well-known things, such as fluororesins, such as glass fiber, a cellulose fiber, a filter paper, and a tetrafluoroethylene resin, are used preferably, Especially a ceramic, a metal, etc. are used preferably. As absolute filtration precision, 50 micrometers or less are used preferably, 30 micrometers or less are more preferable, 10 micrometers or less are more preferable, 5 micrometers or less are used more preferably. These can also be used combining them suitably. The filter medium may be either a surface type or a depth type, but is preferably used because the depth type does not clog relatively well.

(additive)

The optical film of the present invention includes an ester plasticizer having a structure in which an organic acid and a trivalent or higher alcohol are condensed, an ester plasticizer composed of a polyhydric alcohol and a monovalent carboxylic acid, and an ester plasticizer composed of a polyhydric carboxylic acid and a monohydric alcohol. At least one of a plasticizer, a phenolic antioxidant, a hindered amine light stabilizer, a phosphorus stabilizer, and a sulfur stabilizer is preferably included at least one stabilizer. A metal deactivator, a ultraviolet absorber, a mat agent, a dye, a pigment, and also plasticizers other than the above, antioxidant other than a hindered phenol antioxidant, etc. may be included.

Prevention of oxidation of the film composition, capture of acid generated by decomposition, inhibition or inhibition of decomposition reaction due to radical species caused by light or heat, and the like. Additives are used to suppress the formation of volatile components by decomposition and to impart functions such as moisture permeability and diactivation.

On the other hand, when heat-melting a film composition, a decomposition reaction will become remarkable, and this decomposition reaction may be accompanied by the deterioration of the intensity | strength of the said structural material resulting from coloring or molecular weight fall. In addition, the generation of undesirable volatile components may also occur due to the decomposition reaction of the film composition.

The presence of the above-mentioned additives when heating and melting the film composition is excellent from the viewpoint of suppressing the deterioration of the strength based on deterioration and decomposition of the material or maintaining the strength inherent in the material, and thus the optical film of the present invention can be produced. It is necessary that the above-mentioned additives exist from the viewpoint which can be made.

In addition, the presence of the above-mentioned additives may suppress the formation of colored matter in the visible region at the time of heat melting or suppress or eliminate undesirable performance as an optical film such as transmittance or haze value caused by incorporation of volatile components into the film. It is excellent in that it can be.

In this invention, since the display image of a liquid crystal display image affects when it uses more than 1% in the structure of this invention, haze value is less than 1%, More preferably, it is less than 0.5%. .

In the process of providing retardation at the time of film manufacture, it is a thing which can suppress deterioration of the intensity | strength of the said film composition, or can maintain the intensity | strength inherent in a material. It is because when a film composition falls down by remarkable deterioration, a breakage tends to occur in the said extending process, and it may become impossible to control retardation value.

In the preservation or film forming process of the above-mentioned film composition, the deterioration reaction by oxygen in air may coexist. In this case, it is also preferable in embodying the present invention to use the effect of reducing the oxygen concentration in the air together with the stabilizing action of the additive. This is known in the art as the use of nitrogen or argon as an inert gas, degassing under reduced pressure or vacuum, and under an enclosed environment. It is preferable to use at least one of these three methods together with the additive. Deterioration of the material can be suppressed by reducing the probability that the film composition is in contact with oxygen in the air, which is preferable for the purposes of the present invention.

Since the optical film of this invention is utilized as a polarizing plate protective film, it is preferable that the above-mentioned additive exists in a film composition from a viewpoint of improving over time storage characteristics with respect to the polarizing plate and polarizer which comprise the polarizing plate of this invention.

In the liquid crystal display device using the polarizing plate of the present invention, when the above-described additive is present in the optical film of the present invention, the deterioration and deterioration can be suppressed and the time-lapse preservation of the optical film can be improved. The compensation design is stabilized over a long period of time, thereby improving the display quality of the liquid crystal display.

(Antioxidant)

In the present invention, the antioxidant can be used without limitation as long as it is a compound that inactivates radicals generated in the resin or suppresses the deterioration of the resin due to the addition of oxygen to the radicals generated in the resin. A compound, a hindered amine compound, a phosphorus compound, a sulfur type compound, a heat-resistant processing stabilizer, an oxygen scavenger, etc. are mentioned, Among these, a phenol type compound, a hindered amine compound, and a phosphorus compound are especially preferable. By mix | blending these compounds, the coloring of a molded object and the fall of intensity | strength by heat, thermal oxidation deterioration, etc. at the time of melt molding can be prevented, without reducing transparency, heat resistance, etc .. These antioxidants can be used individually or in combination of 2 types or more, respectively.

Phenolic compounds are known compounds and are described, for example, in columns 12 to 14 of US Pat. No. 4,839,405, and include 2,6-dialkylphenol derivative compounds.

Specific examples of the phenolic compound include n-octadecyl3- (3,5-di-t-butyl-4-hydroxyphenyl) -propionate and n-octadecyl3- (3,5-di-t-butyl 4-hydroxyphenyl) -acetate, n-octadecyl 3,5-di-t-butyl-4-hydroxybenzoate, n-hexyl 3,5-di-t-butyl-4-hydroxyphenylbenzo Ate, n-dodecyl 3,5-di-t-butyl-4-hydroxyphenylbenzoate, neo-dodecyl3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate , Dodecylβ (3,5-di-t-butyl-4-hydroxyphenyl) propionate, ethylα- (4-hydroxy-3,5-di-t-butylphenyl) isobutyrate, octadecyl α- (4-hydroxy-3,5-di-t-butylphenyl) isobutyrate, octadecylα- (4-hydroxy-3,5-di-t-butyl-4-hydroxyphenyl) propio Nate, 2- (n-octylthio) ethyl 3,5-di-t-butyl-4-hydroxy-benzoate, 2- (n-octylthio) ethyl 3,5-di-t-butyl-4- Hydroxy-phenylacetate, 2- (n-octadecylthio) ethyl 3,5-di-t-butyl-4-hydroxyphenylacea Tate, 2- (n-octadecylthio) ethyl 3,5-di-t-butyl-4-hydroxy-benzoate, 2- (2-hydroxyethylthio) ethyl 3,5-di-t-butyl 4-hydroxybenzoate, diethylglycol bis- (3,5-di-t-butyl-4-hydroxy-phenyl) propionate, 2- (n-octadecylthio) ethyl3- (3, 5-di-t-butyl-4-hydroxyphenyl) propionate, stearamide N, N-bis- [ethylene3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate ], n-butylimino N, N-bis- [ethylene3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], 2- (2-stearoyloxyethylthio ) Ethyl 3,5-di-t-butyl-4-hydroxybenzoate, 2- (2-stearoyloxyethylthio) ethyl 7- (3-methyl-5-t-butyl-4-hydroxyphenyl ) Heptanoate, 1,2-propylene glycolbis- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], ethylene glycol bis- [3- (3,5- Di-t-butyl-4-hydroxyphenyl) propionate], neopentylglycolbis- [3- (3,5-di-t- Butyl-4-hydroxyphenyl) propionate], ethylene glycol bis- (3,5-di-t-butyl-4-hydroxyphenyl acetate), glycerin-ln-octadecanoate-2,3-bis -(3,5-di-t-butyl-4-hydroxyphenyl acetate), pentaerythritol-tetrakis- [3- (3 ', 5'-di-t-butyl-4'-hydroxyphenyl) Propionate], 1,1,1-trimethylolethane-tris- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], sorbitol hexa- [3- (3 , 5-di-t-butyl-4-hydroxyphenyl) propionate], 2-hydroxyethyl 7- (3-methyl-5-t-butyl-4-hydroxyphenyl) propionate, 2- Stearoyloxyethyl 7- (3-methyl-5-t-butyl-4-hydroxyphenyl) heptanoate, 1,6-n-hexanediol-bis [(3 ', 5'-di-t- Butyl-4-hydroxyphenyl) propionate], pentaerythritol-tetrakis (3,5-di-t-butyl-4-hydroxyhydrocinnamate). Phenolic compounds of this type are commercially available, for example, under the trade names "Irganox 1076" and "Irganox 1010" from Ciba Specialty Chemicals.

Specific examples of the hindered amine compound in the present invention include bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate and bis (2,2,6,6-tetramethyl-4-pi Ferridyl) succinate, bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, bis (N-octoxy-2,2,6,6-tetramethyl-4- Piperidyl) sebacate, bis (N-benzyloxy-2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (N-cyclohexyloxy-2,2,6,6 Tetramethyl-4-piperidyl) sebacate, bis (1,2,2,6,6-pentamethyl-4-piperidyl) 2- (3,5-di-t-butyl-4-hydride Oxybenzyl) -2-butylmalonate, bis (1-acroyl-2,2,6,6-tetramethyl-4-piperidyl) 2,2-bis (3,5-di-t-butyl- 4-hydroxybenzyl) -2-butylmalonate, bis (1,2,2,6,6-pentamethyl-4-piperidyl) decanedioate, 2,2,6,6-tetramethyl-4 -Piperidyl methacrylate, 4- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy] -1- [2- (3- (3,5-di- t-butyl-4-hydroxyphenyl) prop Pionyloxy) ethyl] -2,2,6,6-tetramethylpiperidine, 2-methyl-2- (2,2,6,6-tetramethyl-4-piperidyl) amino-N- ( 2,2,6,6-tetramethyl-4-piperidyl) propionamide, tetrakis (2,2,6,6-tetramethyl-4-piperidyl) 1,2,3,4-butanetetra Carboxylate, tetrakis (1,2,2,6,6-pentamethyl-4-piperidyl) 1,2,3,4-butanetetracarboxylate and the like. Furthermore, a compound of a polymer type may be used, and specific examples are N, N ', N' ', N' ''-tetrakis- [4,6-bis- [butyl- (N-methyl-2,2,6,6- Tetramethylpiperidin-4-yl) amino] -triazin-2-yl] -4,7-diazadecan-1,10-diamine, dibutylamine and 1,3,5-triazineN; N'-bis (2,2,6,6-tetramethyl-4-piperidyl) -1,6-hexamethylenediamine and N- (2,2,6,6-tetramethyl-4-piperidyl Polycondensate of butylamine, polycondensate of dibutylamine, 1,3,5-triazine, N, N'-bis (2,2,6,6-tetramethyl-4-piperidyl) butylamine, poly [{(1,1,3,3-tetramethylbutyl) amino-1,3,5-triazine-2,4-diyl} {(2,2,6,6-tetramethyl-4-piperidyl ) Imino} hexamethylene {(2,2,6,6-tetramethyl-4-piperidyl) imino}], 1,6-hexanediamine-N, N'-bis (2,2,6, Polycondensate of 6-tetramethyl-4-piperidyl) and morpholine-2,4,6-trichloro-1,3,5-triazine, poly [(6-morpholino-s-triazine- 2,4-diyl) [(2,2,6,6, -tetramethyl-4-piperidyl) Mino] - hexamethylene [(2,2,6,6-tetramethyl-4-piperidyl) imino]], such as the piperidine ring is a triazine skeleton through a combination of multiple high molecular weight HALS; Polymer of dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol, 1,2,3,4-butanetetracarboxylic acid and 1,2,2,6,6 Mixed esters of pentamethyl-4-piperidinol with 3,9-bis (2-hydroxy-1,1-dimethylethyl) -2,4,8,10-tetraoxaspiro [5,5] undecane Although the compound etc. which the piperidine ring couple | bonded through an ester bond, such as a cargo, are mentioned, It is not limited to these. Among these, polycondensates of dibutylamine, 1,3,5-triazine and N, N'-bis (2,2,6,6-tetramethyl-4-piperidyl) butylamine, poly [{(1, 1,3,3-tetramethylbutyl) amino-1,3,5-triazine-2,4-diyl} {(2,2,6,6-tetramethyl-4-piperidyl) imino} hexa Methylene {(2,2,6,6-tetramethyl-4-piperidyl) imino}], dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol It is preferable that number average molecular weights (Mn) are 2,000-5,000 in the superposition | polymerization of these.

Hindered phenol compounds of this type are commercially available from, for example, "Tinuvin 144" and "Tinuvin 770" from Ciba Specialty Chemicals under the trade name "ADK STAB LA-52" from Asahi Denka Kogyo KK.

Specific examples of the phosphorus compound in the present invention include triphenylphosphite, diphenylisodecylphosphite, phenyldiisodecylphosphite, tris (nonylphenyl) phosphite, tris (dinonylphenyl) phosphite, and tris (2,4). -Di-t-butylphenyl) phosphite, 10- (3,5-di-t-butyl-4-hydroxybenzyl) -9,10-dihydro-9-oxa-10-phosphaphenanthrene-10 -Oxide, 6- [3- (3-t-butyl-4-hydroxy-5-methylphenyl) propoxy] -2,4,8,10-tetra-t-butyldibenz [d, f] [ 1.3.2] monophosphite compounds such as dioxaphosphine; 4,4'-butylidene-bis (3-methyl-6-t-butylphenyl-di-tridecylphosphite), 4,4'-isopropylidene-bis (phenyl-di-alkyl (C12 to C15) And diphosphite compounds such as phosphite). Phosphorus-based compounds of this type are, for example, "Sumilizer GP" from Sumitomo Chemical Co., Ltd., "ADK STAB PEP-24G" and "ADK STAB PEP-36" from Asahi Denka Kogyo Co., Ltd. It is commercially available.

Specific examples of the sulfur compound in the present invention include dilauryl 3,3-thiodipropionate, dimyristyl 3,3'-thiodipropionate, distearyl 3,3-thiodipropionate, lauryl Stearyl 3,3-thiodipropionate, pentaerythritol-tetrakis (β-lauryl-thio-propionate), 3,9-bis (2-dodecylthioethyl) -2,4,8 , 10-tetraoxaspiro [5,5] undecane and the like. Sulfur compounds of this type are commercially available, for example, under the trade names "Sumilezer TPL-R" and "Sumilezer TP-D" from Sumitomo Chemical Co., Ltd ..

The addition amount of antioxidant is 0.01-25 mass parts normally with respect to 100 mass parts of cellulose esters, Preferably it is 0.05-10 mass parts, More preferably, it is 0.1-3 mass parts.

It is preferable to remove impurities, such as a residual acid, an inorganic salt, and an organic low molecule | numerator which the antioxidant skipped from manufacture or generate | occur | produce during manufacture similarly to the cellulose resin mentioned above, More preferably, it is 99% or more of purity. As residual acid and water, it is preferable that it is 0.01-100 ppm, and heat deterioration can be suppressed in melt-casting film forming resin, and film forming stability, optical properties of a film, and mechanical properties are improved.

(Plasticizer)

In this invention, it is preferable to contain 1-25 mass% of ester compounds which have a structure which the organic acid and trivalent or more alcohol condensed as a plasticizer. If it is less than 1 mass%, the effect of adding a plasticizer is not recognized, and if it is more than 25 mass%, bleed out will likely occur and the time-lapse stability of a film will not be preferable. More preferably, it is an optical film containing 3-20 mass% of said plasticizers, More preferably, it is an optical film containing 5-15 mass%.

A plasticizer is generally an additive which has the effect of improving fragility or giving flexibility by adding to a polymer. In the present invention, in order to lower the melting temperature than the melting temperature of the cellulose ester alone, the plasticizer alone is used at the same heating temperature. In order to lower the melt viscosity of the film composition containing a plasticizer, a plasticizer is added. Moreover, since it is added also in order to improve the hydrophilicity of a cellulose ester and to improve the water vapor transmission rate of an optical film, it has a function as a moisture absorption inhibitor.

Here, the melting temperature of a film composition means the temperature of the state in which the said material was heated and fluidity was expressed. In order to melt-flow a cellulose ester, it is necessary to heat at least higher than the glass transition temperature. Above the glass transition temperature, the elastic modulus or the viscosity decreases due to the absorption of heat and the fluidity is expressed. However, in the cellulose ester, the molecular weight of the cellulose ester may decrease due to thermal decomposition at the same time as melting under high temperature, and may adversely affect the mechanical properties of the resulting film. Therefore, it is necessary to melt the cellulose ester at the lowest possible temperature. There is. In order to lower the melting temperature of a film composition, it can achieve by adding the plasticizer which has melting | fusing point or glass transition temperature lower than the glass transition temperature of a cellulose ester. In particular, a polyhydric alcohol ester plasticizer having a structure in which an organic acid and a polyhydric alcohol are condensed lowers the melting temperature of the cellulose ester, has low volatility even after the melt film forming process or production, and has good process suitability, and the optical of the optical film obtained. It is excellent in that a characteristic, dimension stability, and flatness become favorable.

In addition, in this invention, single type or multiple types may be sufficient as the organic acid which replaces the hydroxyl group of a trivalent or more alcohol.

In this invention, as a trivalent or more alcohol compound which reacts with an organic acid and forms a polyhydric alcohol ester compound, Preferably it is a 3-20 valent aliphatic polyhydric alcohol.

As an example of a preferable polyhydric alcohol, although the following is mentioned, for example, this invention is not limited to these.

Adonitol, arabitol, 1,2,4-butanetriol, 1,2,3-hexanetriol, 1,2,6-hexanetriol, glycerin, diglycerin, erythritol, pentaerythritol, di Pentaerythritol, tripentaerythritol, galactitol, glucose, cellobiose, inositol, mannitol, 3-methylpentane-1,3,5-triol, pinacol, sorbitol, trimethylolpropane, trimethylolethane, xyl Toll, etc. are mentioned. In particular, glycerin, trimethylol ethane, trimethylol propane and pentaerythritol are preferable.

The ester of an organic acid and a trihydric or higher polyhydric alcohol can be synthesized by a known method. A method of condensing an organic acid with a polyhydric alcohol, for example, in the presence of an acid, a method of reacting the organic acid with an acid chloride or an acid anhydride beforehand with a polyhydric alcohol, and a method for reacting the phenyl ester of the organic acid with a polyhydric alcohol Etc., and it is preferable to select the method with a good yield suitably according to the target ester compound.

Although there is no restriction | limiting in particular in the molecular weight of the polyhydric alcohol ester obtained in this way, It is preferable that it is 300-1500, It is more preferable that it is 400-1000. The larger the molecular weight is, the more difficult it is to volatilize, and the smaller is preferable in terms of moisture permeability and compatibility with the cellulose ester.

You may use together the optical film of this invention with another plasticizer.

Since the ester compound which consists of an organic acid which is a preferable plasticizer for this invention, and a trivalent or more polyhydric alcohol is high in compatibility with a cellulose ester, and can be added with a high addition rate, it is bleed out even if it uses another plasticizer and an additive together. It does not generate | occur | produce and can use together another plasticizer and an additive easily as needed.

Moreover, when using another plasticizer together, it is preferable that the plasticizer which consists of an ester compound which consists of an organic acid and a trivalent or more polyhydric alcohol contains at least 50 mass% or more of the whole plasticizer. More preferably, it is 70% or more, More preferably, it contains 80% or more. If it is used in such a range, the fixed effect that the flatness of the cellulose-ester film at the time of melt casting can be improved also by using together with another plasticizer.

The following plasticizer is mentioned as another preferable plasticizer.

(Ester plasticizer consisting of polyhydric alcohol and monovalent carboxylic acid, ester plasticizer consisting of polyhydric carboxylic acid and monohydric alcohol)

Ester plasticizer which consists of polyhydric alcohol and monovalent carboxylic acid, and ester plasticizer which consists of polyhydric carboxylic acid and monohydric alcohol is preferable because it has high affinity with a cellulose ester.

Ethylene glycol ester plasticizer which is one of polyhydric alcohol esters: Specifically, plasticizers of ethylene glycol alkyl esters such as ethylene glycol diacetate and ethylene glycol dibutyrate, ethylene glycol dicyclopropyl carboxylate, ethylene glycol dicyclohexyl And ethylene glycol aryl ester plasticizers such as ethylene glycol cycloalkyl ester plasticizers such as carboxylate, ethylene glycol dibenzoate and ethylene glycol di4-methylbenzoate. These alkylate groups, cycloalkylate groups, and arylate groups may be the same or different and may be substituted. Moreover, the mixture of an alkylate group, a cycloalkylate group, and an arylate group may be sufficient, and these substituents may couple | bond with the covalent bond. The ethylene glycol moiety may also be substituted, the partial structure of the ethylene glycol ester may be partially or pendant to the polymer, or may be incorporated into a part of the molecular structure of additives such as antioxidants, acid scavengers, and ultraviolet absorbers. .

Glycerin ester plasticizer which is one of polyhydric alcohol esters: Specifically, glycerin alkyl esters, such as triacetin, tributyrin, glycerin diacetate caprylate, and glycerin oleate propionate, glycerin tricyclopropyl carboxylate, Glycerin aryl esters such as glycerin tricyclohexyl carboxylate, glycerin tribenzoate, glycerin 4-methylbenzoate, diglycerine tetraacetylate, diglycerine tetrapropionate, diglycerine acetate tricapryl Diglycerin cycloalkyl esters, such as diglycerol alkyl esters, such as a acrylate and diglycerin tetralaurate, diglycerin tetracyclobutyl carboxylate, and a diglycerin tetracyclopentyl carboxylate, diglycerin tetrabenzoate, and a diggle Diglycerin aryl ester, such as a lyserine 3-methylbenzoate, etc. are mentioned. These alkylate groups, cycloalkylcarboxylate groups, and arylate groups may be the same or different and may be substituted. Moreover, the mixture of an alkylate group, a cycloalkylcarboxylate group, and an arylate group may be sufficient, and these substituents may couple | bond with the covalent bond. The glycerin and diglycerin moieties may also be substituted, and the partial structures of the glycerin ester and the diglycerin ester may be partially or regularly pendant to the polymer, and part of the molecular structure of additives such as antioxidants, acid scavengers and ultraviolet absorbers. It may be introduced to.

Specific examples of the polyhydric alcohol ester plasticizer include polyhydric alcohol ester plasticizers described in paragraphs [0030] to [0033] of JP-A-2003-12823.

These alkylate groups, cycloalkylcarboxylate groups, and arylate groups may be the same or different and may be substituted. Moreover, the mixture of an alkylate group, a cycloalkylcarboxylate group, and an arylate group may be sufficient, and these substituents may couple | bond with the covalent bond. In addition, the polyhydric alcohol moiety may be substituted, the partial structure of the polyhydric alcohol may be partially or pendant to the polymer, or may be introduced into a part of the molecular structure of additives such as antioxidants, acid scavengers, and ultraviolet absorbers.

In the ester plasticizer which consists of the said polyhydric alcohol and monohydric carboxylic acid, alkyl polyhydric alcohol aryl ester is preferable, Specifically, the said ethylene glycol dibenzoate, glycerine tribenzoate, diglycerin tetrabenzoate, Japanese Unexamined Patent Publication Exemplary compound 16 described in paragraph No. [0032] of 2003-12823 publication is mentioned.

The dicarboxylic acid ester plasticizer which is one of polyhydric carboxylic acid ester type | system | groups: Alkyl dicarboxyls, such as a dodecyl malonate (C1), a dioctyl adipate (C4), and a dibutyl sebacate (C8), specifically, Alkyl dicarboxylic acid, such as an alkyl dicarboxylic acid cycloalkyl ester plasticizer, such as an acidic alkyl ester plasticizer, a dicyclopentyl succinate, and a dicyclohexyl adipate, a diphenyl succinate, and di4-methylphenyl glutarate Cycloalkyl dicarboxylic acid alkyl esters, such as an acid aryl ester plasticizer, dihexyl-1, 4- cyclohexane dicarboxylate, and didecyl bicyclo [2.2.1] heptane-2,3- dicarboxylate Plasticizer of cycloalkyldicarboxylic acid cycloalkyl ester system, such as a plasticizer, dicyclohexyl-1,2-cyclobutanedicarboxylate, dicyclopropyl-1,2-cyclohexyl dicarboxylate, and diphenyl- 1,1-cyclopropyldica Cycloalkyl dicarboxylic acid aryl ester plasticizers, such as a carboxylate and di2-naphthyl- 1, 4- cyclohexanedicarboxylate, a diethyl phthalate, a dimethyl phthalate, a dioctyl phthalate, a dibutyl phthalate, and a di- Plasticizers of aryldicarboxylic acid alkyl esters such as 2-ethylhexyl phthalate, plasticizers of aryldicarboxylic acid cycloalkyl esters such as dicyclopropyl phthalate, dicyclohexyl phthalate, diphenyl phthalate, di4-methylphenyl phthalate Aryl dicarboxylic acid aryl ester type plasticizers, such as these, are mentioned. These alkoxy groups and cycloalkoxy groups may be the same or different, and may be substituted by 1, and these substituents may further be substituted. An alkyl group and a cycloalkyl group may be a mix, and these substituents may couple | bond with the covalent bond. Moreover, the aromatic ring of phthalic acid may also be substituted, and multimers, such as a dimer, a trimer, and a tetramer, may be sufficient. In addition, the partial structure of the phthalate ester may be pendant to the polymer partly or regularly, or may be incorporated into part of the molecular structure of additives such as antioxidants, acid scavengers and ultraviolet absorbers.

Specific examples of other polyvalent carboxylic acid ester plasticizers include alkyl polyhydric carboxylic acid alkyl esters such as tridodecyltricarbarate and tributyl-meso-butane-1,2,3,4-tetracarboxylate. Alkyl polyhydric carboxylic acid cycloalkyl ester plasticizers, such as a plasticizer of the type | system | group, a tricyclohexyl tricarbarate, and a tricyclo propyl- 2-hydroxy-1,2,3- propane tricarboxylate, and a triphenyl 2- Alkyl polyhydric carboxylic acid aryl ester plasticizers, such as hydroxy-1,2,3-propanetricarboxylate and tetra3-methylphenyltetrahydrofuran-2,3,4,5-tetracarboxylate, tetrahexyl Plasticizers of cycloalkyl polyhydric carboxylic acid alkyl esters such as -1,2,3,4-cyclobutanetetracarboxylate and tetrabutyl-1,2,3,4-cyclopentanetetracarboxylate, tetracyclopropyl -1,2,3,4-cyclobutanetetracarbox Cycloalkyl polyhydric carboxylic acid cycloalkyl ester plasticizers, such as a silate and a tricyclohexyl-1,3,5-cyclohexyl tricarboxylate, triphenyl-1,3,5-cyclohexyl tricarboxylate, Cycloalkyl polyhydric carboxylic acid aryl ester plasticizers such as hexa4-methylphenyl-1,2,3,4,5,6-cyclohexyl hexacarboxylate, tridodecylbenzene-1,2,4-tricar Aryl polyhydric carboxylic acid alkyl ester plasticizers, such as a carboxylate and tetraoctyl benzene- 1,2,4,5- tetracarboxylate, a tricyclo pentyl benzene- 1,3,5- tricarboxylate, tetracyclo Aryl polyhydric carboxylic acid cycloalkyl ester plasticizers such as hexylbenzene-1,2,3,5-tetracarboxylate, triphenylbenzene-1,3,5-tetracartoxylate, hexa4-methylphenylbenzene- Aryl polyhydric carboxylic acid aryl ester type plasticizers, such as 1,2,3,4,5,6-hexacarboxylate, are mentioned. Can be. These alkoxy groups and cycloalkoxy groups may be the same or different, and may be substituted by 1, and these substituents may further be substituted. An alkyl group and a cycloalkyl group may be a mix, and these substituents may couple | bond with the covalent bond. Moreover, the aromatic ring of phthalic acid may also be substituted, and multimers, such as a dimer, a trimer, and a tetramer, may be sufficient. In addition, the partial structure of the phthalate ester may be pendant to the polymer partly or regularly, or may be incorporated into part of the molecular structure of additives such as antioxidants, acid scavengers and ultraviolet absorbers.

In the ester plasticizer which consists of the said polyhydric carboxylic acid and monohydric alcohol, a dialkyl carboxylic acid alkyl ester is preferable, and the said dioctyl adipate and a tridecyl tricarbarate are mentioned specifically ,.

(Other plasticizers)

As another plasticizer used for this invention, a phosphate ester plasticizer, a polymer plasticizer, etc. are mentioned further.

Phosphate ester plasticizers: Specifically, phosphate alkyl esters such as triacetyl phosphate and tributyl phosphate, phosphate cycloalkyl esters such as tricyclopentyl phosphate and cyclohexyl phosphate, triphenyl phosphate, tricresyl phosphate and cresyl phenyl phosphate And phosphate aryl esters such as octyl diphenyl phosphate, diphenyl biphenyl phosphate, trioctyl phosphate, tributyl phosphate, trinaphthyl phosphate, trixylyl phosphate and trisortho-biphenyl phosphate. These substituents may be the same or different and may be further substituted. Moreover, the mixture of an alkyl group, a cycloalkyl group, and an aryl group may be sufficient, and substituents may couple | bond with the covalent bond.

Moreover, alkylene bis (dialkyl phosphate), such as ethylene bis (dimethyl phosphate) and butylene bis (diethyl phosphate), alkylene bis (diaphthyl phosphate), such as ethylene bis (diphenyl phosphate) and propylene bis (dinaphthyl phosphate) Arylene bis (dialkyl phosphate), phenylene bis (diphenyl phosphate), naphthylene bis (dtolyl phosphate), such as yl phosphate), phenylene bis (dibutyl phosphate), biphenylene bis (dioctyl phosphate) Phosphoric acid ester, such as arylene bis (diaryl phosphate), such as these, is mentioned. These substituents may be the same or different and may be further substituted. Moreover, the mixture of an alkyl group, a cycloalkyl group, and an aryl group may be sufficient, and substituents may couple | bond with the covalent bond.

In addition, the partial structure of the phosphate ester may be partially or regularly pendant from the polymer, or may be introduced into a part of the molecular structure of additives such as antioxidants, acid scavengers, and ultraviolet absorbers. In the said compound, phosphate aryl ester and arylene bis (diaryl phosphate) are preferable, and triphenyl phosphate and phenylene bis (diphenyl phosphate) are specifically, preferable.

Polymer plasticizers: Specifically, aliphatic hydrocarbon-based polymers, alicyclic hydrocarbon-based polymers, acrylic polymers such as ethyl polyacrylate and methyl polymethacrylate, vinyl polymers such as polyvinyl isobutyl ether and polyN-vinylpyrrolidone, Styrene-based polymers such as polystyrene and poly4-hydroxystyrene, polyesters such as polybutylene succinate, polyethylene terephthalate, polyethylene naphthalate, polyethers such as polyethylene oxide, polypropylene oxide, polyamide, polyurethane And polyurea. The number average molecular weight is preferably about 1,000 to 500,000, particularly preferably 5000 to 200000. In 1000 or less, a problem arises in volatility, and when it exceeds 500000, plasticization ability falls and it adversely affects the mechanical properties of a cellulose-ester film. These polymer plasticizers may be homopolymers composed of one type of repeating unit, or may be a copolymer having a plurality of repeating structures. In addition, you may use together and use 2 or more types of said polymers.

Moreover, since the optical film of this invention affects an optical use when it is colored, Preferably it is yellowness (yellow index, YI) 3.0 or less, More preferably, it is 1.0 or less. Yellowness can be measured based on JIS-K7103.

The plasticizer preferably removes impurities such as residual acids, inorganic salts, organic low molecules, etc., which are passed from the time of manufacture or generated during storage, like the cellulose esters described above, and more preferably have a purity of 99% or more. As residual acid and water, it is preferable that it is 0.01-100 ppm, and heat deterioration can be suppressed in melt-forming a cellulose resin, and film forming stability, the optical property of a film, and mechanical properties are improved.

(UV absorber)

As a ultraviolet absorber, it is preferable that it is excellent in the absorption ability of the ultraviolet-ray below wavelength 370nm from the viewpoint of the prevention of deterioration with respect to the ultraviolet-ray of a polarizer and a display apparatus, and the absorption of visible light of wavelength 400nm or more from a viewpoint of liquid crystal display is preferable. For example, an oxybenzophenone type compound, a benzotriazole type compound, a salicylic acid ester type compound, a benzophenone type compound, a cyanoacrylate type compound, a nickel complex salt type compound, etc. are mentioned, A benzophenone type compound and a benzo with little coloring are mentioned, for example. Triazole type compounds are preferable. Moreover, the structure of a ultraviolet absorber may be multimers, such as a dimer, trimer, and tetramer, in which several parts which have ultraviolet absorbing power exist in 1 molecule, Unexamined-Japanese-Patent No. 10-182621, 8-337574. You may use the ultraviolet absorber of Unexamined-Japanese-Patent and the polymeric ultraviolet absorber of Unexamined-Japanese-Patent No. 6-148430.

Specific examples of useful benzotriazole-based ultraviolet absorbers 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" -tetrahydrophthalimidemethyl) -5'-methylphenyl) benzotriazole , 2,2-methylenebis (4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol), 2- (2'-hydroxy-3 '-tert-butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2- (2H-benzotriazol-2-yl) -6- (straight and branched 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 A mixture of hydroxy-5- (5-chloro-2H-benzotriazol-2-yl) phenyl] propionate, and the like, but is not limited thereto. No.

Moreover, TINUVIN 109, TINUVIN 171, and TINUVIN 360 (all are the Ciba Specialty Chemicals make) can also be used as a commercial item.

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

In this invention, it is preferable to add 0.1-20 mass% of ultraviolet absorbers, It is preferable to add 0.5-10 mass% further, It is preferable to add 1-5 mass% further. These may use 2 or more types together.

In the manufacturing method of the optical film of this invention, it is preferable that the boiling point temperature of a plasticizer or the said ultraviolet absorber is 300 degrees C or less. When the boiling point temperature is 300 ° C. or lower, when performing atmospheric pressure plasma irradiation or excimer ultraviolet irradiation over almost the entire width of the metal support, an evaporation gas concentration having a concentration sufficient to obtain a reaction rate for forming a dense surface film in a short time is obtained. It is preferable because the surface treatment film can be more stably formed on the surface of the metal support body by being compressed.

As such a plasticizer, an ester plasticizer, a phosphate ester plasticizer, a polymer plasticizer, and a ultraviolet absorber can be mentioned a benzophenone type compound and a benzotriazole type compound as a preferable compound, It is preferable to contain at least one of these compounds in an additive. .

(Antioxidant used at the time of melt film forming)

In the optical film of this invention, it is preferable to contain antioxidant as a stabilizer in the optical film of this invention, since a cellulose ester promotes decomposition not only by heat but also oxygen in the high temperature environment which melt-processing is performed.

The antioxidant useful in the present invention can be used without limitation as long as it is a compound that suppresses deterioration of the molten molding material by oxygen. Among these, useful antioxidants include phenolic compounds, hindered amine compounds, phosphorus compounds, sulfur compounds, and heat resistances. Process stabilizers, oxygen scavengers, etc. are mentioned, Among these, a phenolic compound, a hindered amine compound, and a phosphorus compound are especially preferable. These compounds are synonymous with the compound demonstrated by (Antioxidant used for washing | cleaning a cellulose ester). By compounding these compounds, it is possible to prevent coloration of the molded body or a decrease in strength due to heat during thermal molding, thermal oxidation deterioration, or the like without lowering transparency, heat resistance and the like. These antioxidants can be used individually or in combination of 2 types or more, respectively.

The addition amount of antioxidant is 0.01-10 mass parts normally with respect to 100 mass parts of cellulose esters, Preferably it is 0.05-5 mass parts, More preferably, it is 0.1-3 mass parts.

(Acid scavenger)

An acid scavenger is a agent which plays a role of trapping the acid (protonic acid) which remains in the cellulose ester contained at the time of manufacture. When the cellulose ester is melted, hydrolysis of the side chains is promoted by water and heat in the polymer, and acetic acid and propionic acid are produced when the cap is CAP. Although what is necessary is just to be able to couple | bond with an acid chemically, the compound which has an epoxy, a tertiary amine, an ether structure, etc. is mentioned, It is not limited to this.

Specifically, it is preferable to include an epoxy compound as an acid scavenger described in the specification of US Patent No. 4,137,201. Such epoxy compounds as acid scavengers are known in the art, and polyglycol derived by condensation of various polyglycol diglycidyl ethers, particularly about 8 to 40 moles of ethylene oxide per mole of polyglycol, and the like Metal epoxy compounds (eg, those conventionally used in vinyl chloride polymer compositions and in combination with vinyl chloride polymer compositions), glycerol diglycidyl ethers of glycerol, epoxidized ether condensation products, and diglycols of bisphenol A Cydyl ether (i.e. 4,4'-dihydroxydiphenyldimethylmethane), epoxidized unsaturated fatty acid esters (especially esters of alkyl of about 4 to 2 carbon atoms of fatty acids of 2 to 22 carbon atoms) For example, butyl epoxy stearate) and various epoxidized long-chain fatty acid triglycerides (for example, epoxidized soybean oil, etc.) Representative and oil epoxidized plant oil and other unsaturated natural, which can be exemplified include (as they are sometimes epoxidized natural glycerides or unsaturated fatty acids becoming generic, these acids may generally contain from 12 to 22 carbon atoms)). Especially preferred are commercial epoxy group-containing epoxide resin compounds EPON 815c and other epoxidized ether oligomer condensation products.

Further possible acid scavengers that can be used include those described in paragraphs [0087] to [0105] of JP-A-5-194788.

It is preferable to remove impurities such as residual acid, inorganic salt, organic low molecular weight, etc., which are passed from the time of manufacture or generated during storage, as in the cellulose resin described above, more preferably 99% or more. As residual acid and water, it is preferable that it is 0.01-100 ppm, and heat deterioration can be suppressed in melt-forming a cellulose resin, and film forming stability, the optical property of a film, and mechanical properties are improved.

In addition, although an acid scavenger may be called an acid trapping agent, an acid trapping agent, an acid catcher, etc., it can be used without difference by these names in this invention.

(Viscosity reducing agent)

In this invention, a hydrogen bond solvent can be added for the purpose of reducing melt viscosity. Hydrogen-bonded solvents are described in J. N. Israel Achibili, Molecular Forces and Surface Forces (Kondo Damots, Oshima Hiroyuki Station, McGrawhill Publishing, 1991), and electrically negative atoms (oxygen, nitrogen, fluorine, chlorine) and Organic solvents capable of generating hydrogen atom-mediated "bonds" occurring between electrically negative atoms and covalently bonded hydrogen atoms, i.e., bonds having a large bonding moment and containing hydrogen, such as OH (oxygen hydrogen bonds) And an organic solvent in which adjacent molecules can be arranged by including NH (nitrogen hydrogen bond) and FH (fluorine hydrogen bond). These have the ability to form stronger hydrogen bonds with cellulose than the intermolecular hydrogen bonds of the cellulose resins, and in the melt casting method of the present invention, the addition of hydrogen-bonding solvents is more preferable than the glass transition temperature of the cellulose resins alone. The melting temperature of a cellulose resin composition can be reduced by this, or the melt viscosity of the cellulose resin composition containing a hydrogen bond solvent rather than a cellulose resin can be reduced at the same melting temperature.

Examples of the hydrogen bonding solvent include alcohols, for example methanol, ethanol, propanol, isopropanol, n-butanol, sec-butanol, t-butanol, 2-ethylhexanol, heptanol, octanol, nonanol, Dodecanol, ethylene glycol, propylene glycol, hexylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, methyl cellosolve, ethyl cellosolve, butyl cellosolve, hexyl cellosolve, glycerin and the like, ketones: acetone Carboxylic acids, such as methyl ethyl ketone, for example, formic acid, acetic acid, propionic acid, butyric acid, etc. Ethers: For example, diethyl ether, tetrahydrofuran, dioxane, etc. Pyrrolidones: For example, N-methyl Amines, such as pyrrolidone, For example, trimethylamine, a pyridine, etc. can be illustrated. These hydrogen bond solvents can be used individually or in mixture of 2 or more types. Among these, alcohols, ketones and ethers are preferable, and methanol, ethanol, propanol, isopropanol, octanol, dodecanol, ethylene glycol, glycerin, acetone and tetrahydrofuran are particularly preferable. In addition, water-soluble solvents such as methanol, ethanol, propanol, isopropanol, ethylene glycol, glycerin, acetone, tetrahydrofuran are particularly preferred. Water solubility means here that the solubility with respect to 100 g of water is 10 g or more.

(Retardation control agent)

In the optical film of the present invention, an alignment film may be formed to form a liquid crystal layer, the optical film and the retardation derived from the liquid crystal layer may be combined to perform a polarizing plate processing having imparted optical compensation capability. The compound added in order to control the retardation may use an aromatic compound having two or more aromatic rings as described in European Patent No. 911,656A2 as a retardation control agent. Moreover, you may use together 2 or more types of aromatic compounds. The aromatic ring of the aromatic compound includes an aromatic hetero ring in addition to the aromatic hydrocarbon ring. It is especially preferable that it is an aromatic hetero ring, and an aromatic hetero ring is generally an unsaturated hetero ring. Especially, the compound which has a 1,3,5-triazine ring is especially preferable.

(Mat made)

In order to provide slipperiness | lubricacy, microparticles | fine-particles, such as a mat agent, can be added to the optical film of this invention, and microparticles | fine-particles of an inorganic compound or microparticles | fine-particles of an organic compound are mentioned as microparticles | fine-particles. The mat agent is preferably as fine as possible, and examples of the fine particles include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, kaolin, talc, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate and phosphoric acid. Inorganic fine particles, such as calcium, and crosslinked polymer fine particles. Especially, since silicon dioxide can make the haze of a film low, it is preferable. Particles such as silicon dioxide are often surface-treated with an organic substance, but such a thing is preferable because it can lower the haze of the film.

Examples of preferred organic substances for surface treatment include halosilanes, alkoxysilanes, silazanes, and siloxanes. The larger the average particle size of the fine particles is, the greater the slippery effect, and the smaller the average particle size is, the more excellent the transparency. In addition, the average particle diameter of the secondary particle of microparticles | fine-particles is the range of 0.05-1.0 micrometer. 5-50 nm is preferable and, as for the average particle diameter of the secondary particle of preferable microparticles | fine-particles, More preferably, it is 7-14 nm. These microparticles | fine-particles are used preferably because they produce 0.01-1.0 micrometer of unevenness | corrugation in the optical film surface in an optical film. As for the addition amount of the mat agent in this invention, 0.01-10 g is preferable per 1 m <2> of cellulose-ester films.

Examples of the fine particles of silicon dioxide include AEROSIL 200, 200V, 300, R972, R972V, R974, R202, R812, OX50, TT600, etc. manufactured by Nippon Aerosol Co., Ltd., preferably Aerosol 200V, R972, R972V, R974, R202, R812. You may use together 2 or more types of these microparticles | fine-particles. When using together 2 or more types, it can mix and use in arbitrary ratios. In this case, fine particles having different average particle diameters or materials, for example, aerosil 200V and R972V, can be used in the range of 0.1: 99.9 to 99.9: 0.1 by mass ratio.

In addition, talc or glass fibers may be added to increase the mechanical strength of the film or to suppress dimensional changes, or particles such as inorganic systems such as aluminum hydroxide and magnesium hydroxide may be added to increase flame retardancy. In addition, the shape of these additives may be any shape, such as spherical shape, plate shape, needle shape, rod shape, and thread shape.

Presence of microparticles | fine-particles in the film used as said addition can also be used for the strength improvement of a film as another purpose. Moreover, it is also possible for the presence of the said microparticle in a film to improve the orientation of the cellulose ester itself which comprises the optical film of this invention.

(Polymer material)

In the optical film of the present invention, polymer materials other than cellulose esters and oligomers may be appropriately selected and mixed. It is preferable that the polymer material and oligomer mentioned above are excellent in compatibility with a cellulose ester, and it is preferable that the transmittance | permeability when it uses as a film is 80% or more, More preferably, it is 90% or more, More preferably, it is 92% or more. The purpose of mixing at least 1 or more types of polymer materials and oligomers other than a cellulose ester includes the meaning performed in order to improve the viscosity control at the time of heat melting, and the film physical property after film processing. In this case, it may contain as other additives mentioned above.

The optical film which concerns on this invention was manufactured by the manufacturing method of the said optical film, As for the thickness of a film, 30-200 micrometers is preferable.

(Polarizing plate)

The polarizing plate which has the optical film of this invention in at least one surface can fully achieve the important role which visualizes the change of the orientation of the liquid crystal by an electric field.

A polarizing plate can be manufactured by a general method. It is preferable to bond the cellulose-ester film of this invention which carried out the alkali saponification process to the at least one surface of the polarizer produced by immersing and stretching a polyvinyl alcohol-type film in the iodine solution using the fully saponified polyvinyl alcohol aqueous solution. You may use the cellulose-ester film of this invention for another side, or you may use another polarizing plate protective film. As a polarizing plate protective film used for the other side with respect to the cellulose-ester film of this invention, a commercially available cellulose-ester film can be used. For example, as a commercially available cellulose ester film, KC8UX2M, KC4UX, KC5UX, KC4UY, KC8UY, KC12UR, KC8UY-HA, KC8UX-RHA (above, manufactured by Konica Minolta Opto Chemical Co., Ltd.) and the like are preferably used. Or you may use films, such as cyclic olefin resin, acrylic resin, polyester, polycarbonate, other than a cellulose ester film as a polarizing plate protective film of the other side. In this case, since saponification ability is low, it is preferable to carry out adhesive processing to a polarizing plate through a suitable adhesive layer.

The polarizing plate of this invention uses the cellulose-ester film of this invention as a polarizing plate protective film on at least one side of a polarizer. At this time, it is preferable that the slow axis of the said cellulose ester film is arrange | positioned so that it may be substantially parallel or orthogonal to the absorption axis of a polarizer.

As one polarizing plate in which this polarizing plate interposes the liquid crystal cell of a transverse electric field switching mode type | mold, it is preferable that the cellulose ester film (especially the above-mentioned cellulose ester film A) of this invention is arrange | positioned at the liquid crystal display cell side.

As a polarizer used preferably for the polarizing plate of this invention, a polyvinyl alcohol-type polarizing film is mentioned, This has the thing which dyed iodine to the polyvinyl alcohol-type film, and dyed dichroic dye. As the polyvinyl alcohol-based film, a modified polyvinyl alcohol-based film modified with ethylene is preferably used. The polarizer film-forming aqueous solution of polyvinyl alcohol, uniaxially stretches and dyes this, or dyes and uniaxially stretches after dyeing, The thing which carried out durability treatment with the boron compound preferably is used.

The film thickness of a polarizer is 5-40 micrometers, Preferably it is 5-30 micrometers, Especially preferably, it is 5-20 micrometers. The single side | surface of the cellulose-ester film of this invention is bonded together on the surface of the said polarizer, and a polarizing plate is formed. Preferably, it joins with the water-based adhesive agent which has fully saponified polyvinyl alcohol etc. as a main component. In addition, in the case of resin films other than a cellulose-ester film, it can bond-process to a polarizing plate through an appropriate adhesion layer.

Since the polarizer is stretched in the uniaxial direction (usually in the longitudinal direction), when the polarizing plate is placed under an environment of high temperature and high humidity, the stretching direction (usually in the longitudinal direction) decreases and extends in the direction orthogonal to the stretching (usually in the width direction). do. As the film thickness of the polarizing plate protective film becomes thinner, the stretching ratio of the polarizing plate becomes larger, and in particular, the amount of shrinkage in the stretching direction of the polarizer is large. Usually, since the extending | stretching direction of a polarizer bonds with the casting | flow_spread direction (MD direction) of a polarizing plate protective film, it is important to suppress the elongation rate of a casting | flow_spread direction especially when thinning a polarizing plate protective film. Since the cellulose-ester film of this invention is excellent in dimensional stability, it is used suitably as such a polarizing plate protective film.

The polarizing plate can further comprise a protective film on one side of the polarizing plate and a separate film on the opposite side. A protective film and a separate film are used for the purpose of protecting a polarizing plate at the time of a polarizing plate shipment, a product inspection, etc.

(Liquid crystal display device)

By assembling the polarizing plate using the optical film of this invention to a liquid crystal display device, the liquid crystal display device excellent in various visibility can be manufactured. The optical film of the present invention is preferably used in reflective, transmissive, semi-transmissive LCD or LCD of various driving methods such as TN type, STN type, STN type, OCB type, HAN type, VA type (PVA type, MVA type), and IPS type. do. In particular, in a display device having a screen of 30 or more types, in particular, 30 to 54 types, there is no white omission or the like at the periphery of the screen, and the effect is maintained for a long time, and a remarkable effect is recognized in the MVA type liquid crystal display device. In particular, there was less color unevenness, glitter, and wave pattern unevenness, so that eyes did not get tired even in long time viewing. Thus, the display apparatus which has the polarizing plate of this invention in at least one surface of a liquid crystal cell is very excellent in display quality.

Example

Hereinafter, although an Example demonstrates this embodiment further more concretely, this invention is not limited to these.

Example 1

(Resin mixture)

89% by weight of cellulose acetate propionate

(Acetyl group substitution degree 1.4, propionyl group substitution degree 1.35, number average molecular weight 60000)

9% by weight of trimethylolpropane tribenzoate

(Plasticizer, melting point 85 ° C)

0.25 wt% antioxidant

(Brand name-IRGANOX XP 420 / FD, product made in Ciba specialty chemicals company)

1.6 wt% of ultraviolet absorbers

(Brand name-TINUVIN 928, product made in Ciba specialty chemicals company, melting point 115 degrees Celsius)

0.15% by weight of mat agent (silica fine particles)

(Brand name-sea host KEP-30: product made in Nippon Shokubai Corporation, average particle size 0.3㎛)

In addition, the measurement of substitution degree of acyl groups, such as an acetyl group, a propionyl group, butyryl group, of cellulose acetate propionate was measured according to the method of the prescription | regulation to ASTM-D 817-96.

(Production of cellulose ester film)

The above materials were mixed with a V-type mixer for 30 minutes, and then melted at 230 ° C. under a nitrogen atmosphere using a twin-screw extruder equipped with a strand die, thereby producing cylindrical pellets having a length of 4 mm and a diameter of 3 mm (not shown). ). The glass transition temperature (Tg) by the differential scanning calorimeter (DSC) measurement of the obtained pellet was 135 degreeC.

In the DSC measurement, about 10 mg of the sample was punched out, punched into an aluminum pan, covered with a lid, and crimped to prepare a sample. The transition point when this was heated up at 10 ° C./min in nitrogen from temperature conditions 30 to 250 ° C., cooled to 20 ° C./min, and further raised to 250 ° C. under the same conditions was described as the glass transition temperature (Tg).

The pellet was dried at a temperature of 100 ° C. for 5 hours to obtain a water content of 100 ppm.

Next, the said pellet was supplied to the single screw extruder 1 shown in FIG. 1, and film forming was performed by the casting die 4 which consists of T dies.

The single screw extruder 1 adjusted the rotation speed of the screw so that the screw diameter was 90 mm and L / D = 30 and the extrusion amount was 140 kg / h. Nitrogen gas was enclosed from the material supply port vicinity, and the inside of the extruder 1 was maintained in nitrogen atmosphere. The extruder 1 and the casting die 4 respectively set the temperature to 240 degreeC. The cast die 4 is a coat hanger type, has a width of 1900 mm, hard chrome plating on the inner wall, and is finished with a mirror surface having a surface roughness of 0.1S. The lip clearance of the casting die 4 was set to 2 mm.

In FIG. 1, the web 10 which came out from the casting die 4 was dropped on the 1st cooling roll 5 of the hard chrome plating mirror surface of roll surface length 2400mm, and was simultaneously roll-temperature length adjusted to 100 degreeC. The film was pressurized by the touch roll 6 of 2400 mm.

In this embodiment, the non-passing section of the web on the surface of the metal support body 5 made of the first cooling roll is made online by the method of the present invention so-called online during film formation. In the section in which the surface of the metal support 5 is exposed during film forming], an atmospheric pressure plasma irradiation apparatus 21 called a remote or downstream system shown in FIG. 2 was used. Moreover, the atmospheric pressure plasma irradiation apparatus 21 is provided in the upper side of the 1st cooling roll (metal support body) 5, and the place where the angle (theta) is 80 degrees.

Here, the interval d between the gas ejection port of the plasma of the atmospheric pressure plasma irradiation apparatus 21 and the first cooling roll (metallic support) 5 is 5 mm, the reaction gas is nitrogen only, and the usage amount is 1 m per irradiation width. It was set as 0.5 m <3> / min. At this time, the atmospheric pressure was 1.0 atm.

The surface of the 1st cooling roll (metal support body) 5 was subjected to atmospheric pressure plasma irradiation treatment over almost the entire width. Thereby, the surface treatment film was formed in the surface of the 1st cooling roll 5, and the resin melt was cast on the surface of the 1st cooling roll 5 after that.

In addition, plasma ejection gas was continuously irradiated during film formation so that the irradiation time of the plasma gas to the surface of the 1st cooling roll (metallic support body) 5 might be set to 0.1 sec.

Since plasma irradiation time here is difficult to measure the exact contact time of the radical contained in a plasma jet gas, and the surface of the 1st cooling roll (metallic support) 5, it is the 1st cooling roll (metallic support) 5 here. Any time on the surface of 이동 was taken as the irradiation time as the time for moving below the plasma jet slit gap h by the gap. For example, when the ejection slit gap h is 2 mm and the circumferential speed of the first cooling roll (metallic support) 5 is 2 mm / sec, the plasma irradiation time is 1 sec.

Moreover, the surface temperature of the 1st cooling roll 5 was set to 120 degreeC which is below the glass transition temperature (Tg = 135 degreeC) of resin, and the melting point of an additive (85 degreeC of melting | fusing point of a plasticizer, and 115 degreeC of melting | fusing point of an ultraviolet absorber).

As described above, according to the method of the present invention, as a result of performing the atmospheric pressure plasma irradiation treatment in the presence of the vapor used for the vapor of the additive and the atmospheric pressure plasma irradiation treatment, the surface of the first cooling roll (metallic support) 5 is treated with an additive such as a plasticizer. It was confirmed that a very dense surface treatment film having a decomposition product as a component was formed.

Thus, the surface treatment film formed in the surface of the 1st cooling roll (metal support body) 5 had a contact angle of 14 degree | times with the said process film.

Next, the resin melt was cast on the first cooling roll (metal support) 5, and the film was pressed at a linear pressure of 5 N / mm using the touch roll 6.

The web 10 pressurized by the 1st cooling roll (metallic support body) 5 and the touch roll 6 is peeled off, and is conveyed to the 2nd cooling roll 7.

And by the presence of such a surface treatment film, the releasability (peelability) of the film from the surface of the 1st cooling roll (metallic support) 5 improves remarkably, and very smooth peelability is obtained and the width direction of a peeling position is obtained. The variation is reduced.

The film which peeled from the 1st cooling roll 5 is then externally contacted with the next 2nd cooling roll 7 and the 3rd cooling roll 8 sequentially, and it solidifies and cools, and peels off with the peeling roll 9.

Here, ratio (S2 / S1) of the circumferential speed S1 of the 1st cooling roll 5 and the circumferential speed S2 of the 2nd cooling roll 7 was set to 1.002.

Subsequently, both ends of the web 10 were gripped with a tenter and stretched in the width direction. It carried out by setting the atmosphere temperature of a tenter to 150 degreeC.

Next, the edge of the cellulose acetate propionate film after stretching is slit with a slitter (not shown), and finally, the cellulose acetate propionate having a thickness of 40 µm and a width of 2000 mm with a winder 13 having an ambient temperature of 25 ° C. The film was wound up. Film formation was performed continuously for 3 days on this condition.

Here, it was 135 degreeC when the glass transition temperature (Tg) of the obtained cellulose acetate propionate film was measured like the above-mentioned raw material pellets.

In addition, the minimum amount of increase in peel force required to peel off the flexible film after cooling from the surface of the first cooling roll (metal support) 5 is 0.3 (N / m) at the start of film formation and 24 hours after film formation. It was.

The variation in the cross nicol transmittance was measured as follows with respect to the cellulose acetate propionate film obtained by the above film forming.

[Measurement of cross nicol transmittance (CNT)]

Using Nippon Bunko Co., Ltd. polarizing film measuring apparatus (VAP-7070), cross nicol transmittance (CNT) at a measurement wavelength of 600 nm at 50 mm intervals in the width direction of the film and at 50 mm intervals in the 300 mm section in the longitudinal direction. ) Was measured, and the difference between the mean value of the entire data and the most deviated value was defined as the deviation width (x10 ^-5 %) of the cross nicol transmittance (CNT) here.

According to this Example 1, the variation in transmittance at a wavelength of 600 nm at the time of cross nicol of the obtained cellulose acetate propionate film was 20 × 10 ⁻⁵ (%). The deviation width | variety of this cross nicol transmittance | permeability (CNT) becomes an index of the retardation value of a film, and the smaller the deviation width, the lower the retardation value of a film.

Thus, according to the method of this invention, the cellulose acetate propionate film which has the optical characteristic which was excellent in transparency and planarity by the fall of the retardation (Re) value of the film in the width direction and the longitudinal direction, and the deviation of the transmittance | permeability of a film significantly reduced. In addition, the production speed can be increased, the productivity of the film can be improved, and moreover, it is possible to meet the demands of thinning, widening and high quality of recent protective films for polarizing plates.

Example 2

A cellulose acetate propionate film is produced in the same manner as in the first embodiment by the method of the present invention, but the difference from the first embodiment is that the surface of the metal support 5 made of the first cooling roll is a resin melt. Before softening, the metal support body 5 which consists of a 1st cooling roll by performing high energy surface treatment with the atmospheric pressure plasma irradiation apparatus 21 at the predetermined position of the surface of the metal support body 5 which consists of a 1st cooling roll so-called offline. The surface treatment film | membrane is formed in the surface of), and the resin melt is cast on the surface of the metal support body 5 after that, and it implemented.

That is, in this Example 2, while fixing 100 g of trimethylolpropane tribenzoate (melting point 85 degreeC) which is a plasticizer to the hot air blower of a hot air generator (brand name TSK-40, KK make) It was injected, and heated and volatilized by blowing hot air at 160 ° C. from the hot air generator, and the vapor was blown to the atmospheric pressure plasma irradiation device through a 10m duct wound with a heat insulating material, and the atmospheric pressure plasma irradiation treatment was performed in the presence of the additive vapor. It was.

In this way, the atmospheric pressure plasma irradiation process was performed by the method of the present invention of Example 2 in the presence of the gas used for the vapor of an additive and an atmospheric pressure plasma irradiation process, and the plasticizer was made to the surface of the 1st cooling roll (metal support body) 5 It was confirmed that a very dense surface treatment film having a decomposition product of an additive such as a constituent component is formed.

In the second embodiment, the surface treatment film formed on the surface of the first cooling roll (metal support) 5 had a contact angle of 12 degrees between the treatment film and water.

Next, the resin melt was cast on the first cooling roll (metal support) 5, and the film was pressed at a linear pressure of 5 N / mm using the touch roll 6.

The web 10 pressurized by the 1st cooling roll (metallic support body) 5 and the touch roll 6 is peeled off, and is conveyed to the 2nd cooling roll 7.

By the presence of such a surface treatment film, the releasability (peelability) of the film from the surface of the 1st cooling roll (metallic support) 5 is improved remarkably, and very smooth peelability is obtained and the fluctuation of the width direction of a peeling position is Decreased.

The film which peeled from the 1st cooling roll 5 was then externally externalized to the next 2nd cooling roll 7 and the 3rd cooling roll 8 similarly to the case of Example 1, and it solidified by cooling, and a peeling roll It peeled by (9), and subsequently formed into a film-forming process, the cellulose acetate propionate film of 40 micrometers in thickness and 2000 mm in width was finally wound up by the winding machine 13. Film formation was performed continuously for 3 days on this condition.

In this Example 2, the minimum increase in peel force required to peel off the flexible film after cooling from the surface of the first cooling roll (metallic support) 5 is 0.6 (N at the beginning of film formation and 24 hours after film formation. / m).

According to this Example 2, the variation in transmittance at a wavelength of 600 nm at the time of cross nicol of the obtained cellulose acetate propionate film was 10 × 10 ⁻⁵ (%). The deviation width | variety of this cross nicol transmittance | permeability (CNT) becomes an index of the retardation value of a film, and the smaller the deviation width, the lower the retardation value of a film.

Example 3

A cellulose acetate propionate film is produced in the same manner as in Example 1 by the method of the present invention. The difference from the case of Example 1 is the excimer ultraviolet irradiation device 22 shown in FIG. ), The surface of the metal support 5 made of the first cooling roll is modified.

As shown in the figure, the ultraviolet irradiation device 22 is disposed above the first cooling roll (metal support) 5, and as the ultraviolet irradiation device 22 with Xe ₂ having a radiation intensity of 40 mW / cm ₂ . An excimer ultraviolet irradiation device 22 containing an excimer ultraviolet (EUV) lamp having a wavelength of 172 nm was used. And the clearance gap d from the surface of the quartz glass q of an excimer ultraviolet lamp to the 1st cooling roll (metallic support body) 5 is set to 5 mm, and angle (theta) in FIG. 3 is 80 degrees. It was set as. In addition, during the film formation, a purge gas made of nitrogen is continuously blown off and continuously irradiated with ultraviolet rays to form a surface treatment film on the surface of the first cooling roll (metal support) 5, and then the surface of the metal support 5. The resin melt was cast on.

In addition, the surface temperature of the 1st cooling roll 5 is the glass transition temperature (Tg = 135 degreeC) or less of resin, melting | fusing point of the additive (melting point of plasticizer 85 degreeC and melting point of ultraviolet absorber 115 degreeC) similarly to the case of the said Example 1 ) To 120 ° C.

Thus, according to the method of this invention, when excimer ultraviolet irradiation process was performed in presence of the purge gas used for the vapor | steam of an additive and an excimer ultraviolet irradiation process, the surface of a 1st cooling roll (metallic support) 5, such as a plasticizer, etc. It was confirmed that the very dense surface treatment film which uses the decomposition product of an additive as a component is formed.

Thus, the surface treatment film formed on the surface of the 1st cooling roll (metal support body) 5 had a contact angle of 7 degree with the said process film.

Next, the resin melt was cast on the first cooling roll (metal support) 5, and the film was pressed at a linear pressure of 5 N / mm using the touch roll 6.

The web 10 pressurized by the 1st cooling roll (metallic support body) 5 and the touch roll 6 is peeled off, and is conveyed to the 2nd cooling roll 7.

And by the presence of such a surface treatment film, the releasability (peelability) of the film from the surface of the 1st cooling roll (metallic support) 5 improves remarkably, and very smooth peelability is obtained and the width direction of a peeling position is obtained. The variation is reduced.

The film which peeled from the 1st cooling roll 5 was then externally externalized to the next 2nd cooling roll 7 and the 3rd cooling roll 8 similarly to the case of Example 1, and it solidified by cooling, and a peeling roll It peeled by (9), and subsequently formed into a film-forming process, the cellulose acetate propionate film of 40 micrometers in thickness and 2000 mm in width was finally wound up by the winding machine 13. Film formation was performed continuously for 3 days on this condition.

In Example 3, the minimum amount of increase in peel force required to peel off the flexible film after cooling from the surface of the first cooling roll (metallic support) 5 is 0.2 (N at the time of film forming start and 24 hours after film forming. / m).

According to this Example 3, the deviation of the transmittance | permeability in wavelength 600nm at the time of cross nicol of the obtained cellulose acetate propionate film was 50x10 <^-5> (%). The deviation width | variety of this cross nicol transmittance | permeability (CNT) becomes an index of the retardation value of a film, and the smaller the deviation width, the lower the retardation value of a film.

Example 4

By the method of the present invention, a cellulose acetate propionate film is produced in the same manner as in the third embodiment, except that the third embodiment differs from the surface of the metal support 5 made of the first cooling rolls, which is a resin melt. The metal support body 5 consisting of a 1st cooling roll by performing high-energy surface treatment with the excimer ultraviolet irradiation device 22 at the predetermined | prescribed position of the surface of the metal support body 5 consisting of a 1st cooling roll, so-called offline before casting | flow_spreading. The surface treatment film | membrane is formed in the surface of the surface, and the resin melt is cast on the surface of the metal support body 5 after that.

In this example, 100 g of a trimethylolpropane tribenzoate (melting point 85 ° C.), which is a plasticizer, was used as a hot air blower in the hot air generator (trade name TSK-40; The stainless steel chalet was fixed in the air, and the hot air at 160 ° C. was blown out and heated and volatilized from the hot air generator, and the steam was blown to the excimer ultraviolet irradiation device through a 10 m duct wound with a heat insulating material, and the presence of additive vapor was present. The excimer ultraviolet irradiation process was performed underneath.

In this way, the excimer ultraviolet irradiation treatment was carried out in the presence of the gas used for the vapor of the additive and the atmospheric pressure plasma irradiation treatment. As a result, the decomposition of an additive such as a plasticizer on the surface of the first cooling roll (metallic support) 5 was used as a component. It was confirmed that a dense surface treatment film was formed.

In Example 4, the surface treatment film formed on the surface of the first cooling roll (metal support) 5 had a contact angle of 15 degrees between the treatment film and water.

Next, the resin melt was cast on the first cooling roll (metal support) 5, and the film was pressed at a linear pressure of 5 N / mm using the touch roll 6.

The web 10 pressurized by the 1st cooling roll (metallic support body) 5 and the touch roll 6 is peeled off, and is conveyed to the 2nd cooling roll 7.

According to this Example 4, the dispersion | variation in the transmittance | permeability in wavelength 600nm at the time of cross nicol of the obtained cellulose acetate propionate film was 30x10 <^-5> (%). The deviation width | variety of this cross nicol transmittance | permeability (CNT) becomes an index of the retardation value of a film, and the smaller the deviation width, the lower the retardation value of a film.

And by the presence of such a surface treatment film, the releasability (peelability) of the film from the surface of the 1st cooling roll (metallic support) 5 improves remarkably, and very smooth peelability is obtained and the width direction of a peeling position is obtained. The variation is reduced.

The film which peeled from the 1st cooling roll 5 was then externally externalized to the next 2nd cooling roll 7 and the 3rd cooling roll 8 similarly to the case of Example 1, and it solidified by cooling, and a peeling roll It peeled by (9), and subsequently formed into a film-forming process, the cellulose acetate propionate film of 40 micrometers in thickness and 2000 mm in width was finally wound up by the winding machine 13. Film formation was performed continuously for 3 days on this condition.

In the fourth embodiment, the minimum amount of increase in peel force required to peel off the flexible film after cooling from the surface of the first cooling roll (metal support) 5 is 0.5 (N at the time of film formation start and 24 hours after film formation. / m).

Comparative Example 1

Melt casting film forming apparatus WHEREIN: The cellulose acetate propionate film is formed into a film without the high energy irradiation processing apparatus which consists of an atmospheric pressure plasma apparatus or an ultraviolet irradiation device on the surface of the 1st cooling roll (metal support body) 5. It carried out using the same material as the case of Example 1.

In this comparative example 1, the contact angle of the surface of the 1st cooling roll (metallic support) 5 and water was 98 degree | times.

In this comparative example 1, the dispersion | variation in the transmittance | permeability in wavelength 600nm at the time of cross nicol of the obtained cellulose acetate propionate film is 130x10 <^-5> (%), and the retardation (Re) value of a film width direction and a longitudinal direction The deviation was also great.

In Comparative Example 1, the minimum amount of increase in peeling force required to peel off the flexible film 10 after cooling from the surface of the metal support 5 was 14.5 (N / N) at the beginning of film formation and 24 hours after film formation. m).

Thus, according to the comparative example 1, the peeling position which peels off a film from the 1st cooling roll 5 starts to fluctuate up and down largely after several hours of film forming start, and after about 24 hours, when the peeling position fluctuates, Stripe-like deformation extending in the width direction appears to occur, and this can be confirmed with the naked eye, and the quality deterioration is remarkable. Therefore, the production is stopped and the cleaning work is performed for about a day, and the productivity is considerably low. .

(Production of polarizing plate)

Next, the polarizing plate was produced using the cellulose acetate propionate film produced by Examples 1-4 and Comparative Example 1 of this invention.

(Polarizing film)

First, the long polyvinyl alcohol film of 120 micrometers in thickness was uniaxially stretched (temperature 110 degreeC, draw ratio 5 times). This was immersed in the aqueous solution which consists of 0.075g of iodine, 5g of potassium iodide, and 100g of water for 60 second, and then immersed in the 68 degreeC aqueous solution which consists of a ratio of 6g of potassium iodide, 7.5g of boric acid, and 100g of water. This was washed with water and dried to obtain a long polarizing film.

(Polarizing plate)

Subsequently, the said polarizing film and the cellulose acetate propionate film produced by Examples 1-4 and Comparative Example 1 were bonded together following the steps 1-5, and the polarizing plate was produced.

Step 1: The long cellulose acetate propionate films produced in Examples 1 to 4 and Comparative Example 1 were immersed in a 2 mol / L sodium hydroxide solution at a temperature of 50 ° C. for 90 seconds, and then washed with water and dried.

On the other hand, the commercially available long cellulose-ester film was immersed in 2 mol / L sodium hydroxide solution at the temperature of 50 degreeC for 90 second, and then washed with water and dried.

Process 2: The said long polarizing film was immersed for 1-2 second in the polyvinyl alcohol adhesive bath of 2 mass% of solid content.

Step 3: The long cellulose acetate propionate film of Examples 1 to 4 and Comparative Example 1 and the commercially available long cellulose ester film of which the excess adhesive adhered to the polarizing film in Step 2 was lightly removed and alkali-treated in Step 1 Sandwiched and stacked.

Process 4: These films were bonded at the speed of about 2 m / min by the pressure of 20-30 N / cm <2> with two rotating rollers. At this time, care was taken so that no bubbles entered.

Process 5: The film sample produced by the process 4 was dried for 2 minutes in 80 degreeC dryer, and the polarizing plate was produced.

(Production of liquid crystal display panel)

The polarizing plate of the outermost surface of a commercially available liquid crystal display panel (NEC color liquid crystal display, MultiSync, LCD1525J, model name LA-1529HM) was carefully peeled off, and the polarizing directions of the polarizing plates of Examples 1 to 4 and Comparative Example 1 described above were It put together and produced the liquid crystal display panel.

(Visual evaluation of the polarizing plate)

The above-mentioned evaluation was performed by the method shown below.

Moreover, observation of the nonuniformity by visual observation of the polarizing plate which used these optical films as a protective film was performed as follows, and the obtained result was shown in following Table 1.

About each liquid crystal display panel produced using the cellulose acetate propionate film by Examples 1-4 and Comparative Example 1 as mentioned above, the color nonuniformity seen when the some evaluator sees from the front and side visually is visually shown. It observed and set it as evaluation of a polarizing plate.

○: no color unevenness was seen at all raters

(Triangle | delta): Although the color nonuniformity may be seen faintly by an evaluator, the level which can be used as a product

X: The level which color nonuniformity was confirmed by many evaluators and cannot use as a product

Moreover, the contamination state of the alkali saponification process liquid of the polarizing plate preparation process 1 after producing 20 polarizing plates as well as evaluation of the color nonuniformity was also observed.

As a result, in Examples 1-4 of this invention, the high energy irradiation processing apparatus which consists of an atmospheric pressure plasma irradiation apparatus 21 or the ultraviolet irradiation apparatus 22 near the surface of the 1st cooling roll (metal support body) 5 is used. A cellulose produced by forming a surface treatment film on the surface of the metal support 5 by providing a high energy irradiation treatment on the surface of the first cooling roll 5 and then casting a resin melt on the surface of the metal support 5. According to the acetate propionate film, the releasing property (peelability) of the film from the metal support 5 is improved, and very smooth peelability is obtained, and the cellulose acetate propionate is reduced in that the variation in the width direction of the peeling position is reduced. As for the film, the variation in transmittance at the wavelength of 600 nm at the time of cross nicol is greatly reduced, and the variation in retardation (Re) value is greatly reduced, thereby providing transparency and flatness. This was excellent. Moreover, since the color nonuniformity which looks white after being processed into a polarizing plate using the cellulose acetate propionate film manufactured by the method of this invention as a polarizing plate protective film is not recognized, continuous film forming of a film is enabled and a productivity is greatly improved. Could.

On the other hand, in the comparative example 1, since the releasability (peelability) of the film from the metal support 5 improves and very smooth peelability is obtained and the fluctuation of the width direction of a peeling position decreases, a cellulose acetate propionate film The variation in the transmittance at a wavelength of 600 nm at the time of cross nicol was large, and the variation in the retardation (Re) value was also large, resulting in poor transparency and flatness.

In addition, since the cellulose acetate propionate film manufactured by the method of Comparative Example 1 was used as a polarizing plate protective film, and after being processed into a polarizing plate, white streaks were clearly seen in the state of cross nicol by the polarizing film, and quality deterioration was remarkable. The production was stopped, and the cleaning work for about a day was forced, and the productivity became quite low.

In addition, the detailed structure and detailed operation | movement of each structure which comprise the manufacturing method of an optical film by this invention, an optical film, a polarizing plate, and a display apparatus can be suitably changed in the range which does not deviate from the meaning of this invention.

1: extruder
2: filter
3: static mixer
4: flexible die
5: first cooling roll
6: touch roll
7: second cooling roll
8: third cooling roll
9: peeling roll
10: Web (film)
11: tenter
12: winder
21: atmospheric pressure plasma irradiation device
22: excimer ultraviolet irradiation device
a, b: electrode
g: reaction gas
d: gap between the surface treatment device and the film
h: plasma gas blowing slit gap
p: purge gas
r: reflector
u: UV lamp
q: quartz glass

Claims (15)

A method for producing an optical film by a melt casting film forming method, the step of forming a flexible film by casting a resin melt containing a thermoplastic resin and an additive on a surface of a metal support, and removing the metal film from the metal support after cooling and solidifying the cast film. And an atmospheric pressure plasma irradiation treatment or an excimer ultraviolet irradiation treatment performed in the presence of a gas used for vapor and atmospheric pressure plasma irradiation or excimer ultraviolet irradiation of the additive, to the surface of the metal support over almost the entire width of the metal support. It has a process of forming a surface treatment film, The manufacturing method of the optical film characterized by the above-mentioned. The process for forming a surface treatment film on the surface of the metal support is performed before the resin melt is cast on the surface of the metal support, and after forming the surface treatment film on the surface of the metal support in advance, A flexible film is formed, The manufacturing method of the optical film characterized by the above-mentioned. The process of claim 1, wherein the forming of the surface treatment film on the surface of the metal support is performed simultaneously with the step of casting the resin melt on the surface of the metal support in a non-passing section of the casting film on the surface of the metal support. The manufacturing method of the optical film characterized by the above-mentioned. The position at which the atmospheric pressure plasma irradiation treatment or the excimer ultraviolet irradiation treatment is performed is near the position where the resin solution in which the vapor of the additive is present is soft on the surface of the metal support. The manufacturing method of the optical film. The method for producing an optical film according to any one of claims 1 to 4, wherein the vapor is a vapor of a plasticizer or an ultraviolet absorber. The said room temperature plasma irradiation process is the electric power supplied between electrodes as processing conditions, 1 W / cm <2> or 50 W / cm <2> (the area of the range which discharge generate | occur | produces) in any one of Claims 1-5. The manufacturing method of the optical film made into. The said excimer ultraviolet irradiation process irradiates the ultraviolet-ray whose main wavelength is 172 nm as a light quantity of 1-3,000mJ / cm <2> as a processing condition, The optical film of any one of Claims 1-5 characterized by the above-mentioned. Manufacturing method. The method for producing an optical film according to any one of claims 1 to 7, wherein the surface treatment film has a contact angle of 5 to 40 degrees between the surface treatment film and water. The said thermoplastic resin is a cellulose-ester type resin, The manufacturing method of the optical film in any one of Claims 1-8 characterized by the above-mentioned. The method of manufacturing an optical film according to any one of claims 1 to 9, wherein the metal support is any one of an endless belt, a drum, or a roll for forming a film. 11. The method according to any one of claims 1 to 10, wherein the minimum amount of increase in peeling force required to peel off the flexible film after cooling from the surface of the metal support is 0.1 to at the beginning of film formation and 24 hours after film formation. It exists in the range of 2.0 (N / m), The manufacturing method of the optical film characterized by the above-mentioned. The optical film manufactured by the manufacturing method of the optical film of any one of Claims 1-11. The optical film according to claim 12, wherein the variation in transmittance at a wavelength of 600 nm at the time of cross nicol of the optical film is in the range of 2x10 ^-5 to 60x10 ^-5 (%). The optical film of Claim 12 or 13 is provided in at least one surface, The polarizing plate characterized by the above-mentioned. The polarizing plate of Claim 14 is used, The display apparatus characterized by the above-mentioned.

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