JP2008111084A - Cellulose ester film, and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cellulose ester film suitable for a phase difference film, surely suppressing an incidence of foreign substances caused by bubble failure at a dope filtration process, producing no foreign substance, and excellent in productivity. <P>SOLUTION: In the method of manufacturing a cellulose ester film by a solution casting film forming method, an ultrafiltration device 2 connected to a main filtrating device 1 with piping is provided together. When dope is initially filled into the main filtrating device 1, the dope whose viscosity is lowered by diluting an ordinary dope is injected initially into the main filtrating device 1 so as to expel air in the main filtrating device 1 and bubbles in the inside of a filtrating material. The low viscous dope discharged from the main filtrating device 1 is introduced to the ultrafiltration device 2, and a solvent is separated and removed to concentrate the dope. The high viscous dope discharged from the ultrafiltration device 2 is recycled to the main filtrating device 1, and thereafter the casting film forming is carried out with a dope having a predetermined viscosity for casting using the main filtrating device 1 with which the initial filling has been finished. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention particularly relates to a cellulose ester film suitable as a protective film and retardation film for a polarizing plate of a liquid crystal display device, and a method for producing the same.

  2. Description of the Related Art Conventionally, liquid crystal display devices (LCD) are used in various places, and high visibility when viewing images is demanded. Particularly, polarizing plates and retardation plates used in LCDs are also like glass. There is a demand for higher image quality without spot defects such as flatness and foreign matter.

  In recent years, higher image quality and higher definition of liquid crystal display devices have been accelerated. Along with this, a demand for reducing foreign substances contained in the film is also increasing for the polarizing plate protective film used in the liquid crystal display device. Since the cellulose ester used for the protective film for polarizing plates is a semi-synthetic polymer, it is strongly influenced not only by the generation of unnecessary components due to the heterogeneous reaction in the esterification process but also by the quality of the starting material. Therefore, the necessity for removing unnecessary components is higher than that of a general synthetic polymer.

  For this reason, conventionally, when producing a cellulose ester film by a solution casting film forming method, a filtration device is arranged upstream of the dope casting part, and before dope casting, by filtering once or more The foreign material is removed from the dope.

Here, prior patent documents relating to a method for producing a cellulose ester film used for a conventional protective film for a polarizing plate include the following.
JP, 2004-323549, A In patent documents 1, in order to collect more fine foreign materials, in filtration of cellulose ester dope, with filter paper characterized by a high gap and a small collection particle diameter, sand is used. Cellulose with improved grain failure due to drastic improvement in particle foreign matter failure, pressure resistance reduction during filtration, improved dope removal during filter paper replacement, and use of filter paper that does not easily cause opening A method for providing an ester film is disclosed. JP-A-2005-178239 discloses a method for producing a cellulose ester film containing fine particles, in which an additive liquid containing fine particles is added to the main dope, and then the collected particle diameter is 0.5 to 5 μm. And the manufacturing method of the cellulose-ester film which filters with a filter medium whose drainage time is 10-25 sec / 100ml, casts this dope, and manufactures a film is disclosed.

  However, according to the method of Patent Document 1 described above, when the fine particle additive solution is filtered with a fine filter in an attempt to reduce foreign matter, the fine particle aggregates adhere to each other with the filter and further aggregate, and the filter is clogged and the filtration pressure is rapidly increased. There was a problem that it often rises.

  Further, in Patent Document 2, the dope is filtered by a filter medium (filter paper) in which the collected particle diameter and the drainage time are defined. However, by removing the aggregates of fine particles only by the filter medium (filter paper), However, there has been a problem that the present state of manufacturing a cellulose ester film as an optical film for which high quality and high productivity have been demanded in recent years is not sufficient.

  In these patent documents, the main focus is on the removal of unnecessary components such as undissolved substances derived from the starting material of cellulose ester, but the patent documents defining the dope filling method in the filtration apparatus have so far been Was never disclosed.

  The object of the present invention is to solve the above-mentioned problems of the prior art, and to reliably suppress the occurrence rate of foreign matters due to foam failure occurring in the cellulose ester film in the dope filtration step, and to prevent the occurrence of subsequent foreign matters. Another object of the present invention is to provide a method for producing a cellulose ester film, which is excellent in productivity, and a cellulose ester film produced by the method.

  As a result of intensive studies in order to solve the above-described problems of the prior art, the present inventor has some foreign substances generated in the cellulose ester film due to generation of bubbles (bubble failure). It has been found. As a result of examining the bubbles in more detail, when the filter apparatus is newly filled with filter paper and then filled with the dope, the foam accumulates in a dead space where the dope is not sufficiently filled in the apparatus. I found out that it was caused by the remaining air.

  In order to achieve the above object, the invention according to claim 1 is a solution casting method in which a dope in which a cellulose ester is dissolved is passed through a main filtration device equipped with a filter medium and then cast on a support. A method for producing a cellulose ester film by a membrane method, wherein an ultrafiltration device connected by piping to the main filtration device is provided side by side, and when the dope is initially filled in the main filtration device, a predetermined The dope having a high viscosity for casting is diluted with a solvent to lower the viscosity, and then injected into the main filtration device to initially fill the air and the air bubbles in the filter medium are expelled. The low-viscosity dope discharged from the main filtration device is introduced into the ultrafiltration device, the solvent is separated and removed by the ultrafiltration membrane in the ultrafiltration device, and the dope is concentrated to a predetermined high viscosity. Place discharged from the filtration device The high-viscosity dope is circulated to the main filtration device, and then cast film formation is performed with the dope having a predetermined high viscosity for casting using the main filtration device after the initial filling is completed. Yes.

  In the invention of claim 2, the dope in which the cellulose ester is dissolved is passed through a main filtration device equipped with a filter medium, and then cast on a support from a casting die, and the cellulose ester is formed by a solution casting film forming method. A method of manufacturing a film, wherein an ultrafiltration device is interposed in a dope flow path between a main filtration device and a casting die, and when a dope is initially filled in the main filtration device, a predetermined flow is obtained. The dope having a high viscosity for casting is added with a solvent to lower the viscosity, and then injected into the main filtration device to initially fill the air, thereby expelling air in the main filtration device and bubbles in the filter medium, The low-viscosity dope discharged from the filtration device is introduced into the ultrafiltration device, the solvent is separated and removed by the ultrafiltration membrane in the ultrafiltration device, the dope is concentrated to a predetermined high viscosity, and ultrafiltration is performed. The specified high-viscosity drain discharged from the device Introducing up to the casting die, then, using the primary filtration device initial filling is completed, by doping with a high viscosity for a given casting, and characterized by performing the casting film.

  In the invention of claim 3, the dope in which the cellulose ester is dissolved is passed through a main filtration device provided with a filter medium, and then cast on a support to produce a cellulose ester film by a solution casting film forming method. In this method, an ultrafiltration device connected by piping to the main filtration device is provided side by side, and in the dope preparation pot in advance, the solvent is 2 to 20 times the solvent contained in the predetermined casting dope When the dope is initially filled in the main filtration device, the low-viscosity dope is initially injected by injecting the low-viscosity dope into the main filtration device. The internal bubbles are expelled, the low-viscosity dope discharged from the main filtration device is introduced into the ultrafiltration device, and the solvent is separated and removed by the ultrafiltration membrane in the ultrafiltration device. On viscosity The dope having a predetermined high viscosity for casting is circulated through the main filtration device after the concentration is concentrated in the step and discharged from the ultrafiltration device to the main filtration device. Thus, casting film formation is performed.

  According to the invention of claim 4, the dope in which the cellulose ester is dissolved is passed through a main filtration device equipped with a filter medium, and then cast on a support from a casting die, and the cellulose ester is formed by a solution casting film forming method. A method for producing a film, wherein an ultrafiltration device is interposed in a dope flow path between a main filtration device and a casting die, and is included in a predetermined casting dope in a dope preparation pot in advance. By preparing a low-viscosity dope containing a solvent 2 to 20 times the solvent and initially filling the dope into the main filtration device, by injecting the low-viscosity dope into the main filtration device and initially filling the dope, The air in the main filter and air bubbles inside the filter medium are driven out, then the low-viscosity dope discharged from the main filter is introduced into the ultrafilter, and the solvent is separated and removed by the ultrafiltration membrane in the ultrafilter. And dope Concentrate to a constant high viscosity, introduce a predetermined high viscosity dope discharged from the ultrafiltration device into the casting die, and then use the main filtration device with the initial filling completed to perform the predetermined casting. It is characterized by performing casting film formation with a dope having high viscosity.

  In the invention of claim 5, the dope in which the cellulose ester is dissolved is passed through a main filtration device equipped with a filter medium, and then cast on a support to produce a cellulose ester film by a solution casting film forming method. In this method, an ultrafiltration device connected by piping to the main filtration device is provided side by side, and when the dope is initially filled in the main filtration device, first, a solvent is injected into the main filtration device. By initial filling, air bubbles inside the filter medium of the main filtration device are expelled, then a dope having a predetermined high viscosity for casting is introduced into the main filtration device, and the solvent discharged from the main filtration device and diluted therewith. The low-viscosity dope was introduced into the ultrafiltration device, the solvent was separated and removed by the ultrafiltration membrane in the ultrafiltration device, the dope was concentrated to a predetermined high viscosity, and discharged from the ultrafiltration device. Predetermined high viscosity Is circulated doped to the main filtering device, then use the primary filtration device initial filling is completed, by doping with a high viscosity for a given casting, and characterized by performing the casting film.

  In the invention of claim 6, the dope in which the cellulose ester is dissolved is passed through a main filtration device provided with a filter medium, and then cast on a support from a casting die, and the cellulose ester is formed by a solution casting film forming method. A method for producing a film, in which an ultrafiltration device is interposed in a dope flow path between a main filtration device and a casting die, and when a dope is initially filled in the main filtration device, first, a solvent Is injected into the main filtration device and initially filled to expel air bubbles inside the filter medium of the main filtration device, and then a dope having a predetermined high viscosity for casting is introduced into the main filtration device. The discharged solvent and the diluted low-viscosity dope are introduced into an ultrafiltration device, and the solvent is separated and removed by an ultrafiltration membrane in the ultrafiltration device, and the dope is concentrated to a predetermined high viscosity. , Discharged from the ultrafiltration device The dope having a predetermined high viscosity is introduced into a casting die, and thereafter, casting is performed with a dope having a predetermined high viscosity for casting using a main filtration device in which initial filling is completed. It is characterized by.

  Invention of Claim 7 is a manufacturing method of the cellulose-ester film as described in any one of Claims 1-6, Comprising: The filter medium of a main filtration apparatus is the collection particle diameter of 0.5-5 micrometers, and It has a drainage time of 10 to 25 sec / 100 ml.

  Invention of Claim 8 is a manufacturing method of the cellulose-ester film as described in any one of Claims 1-6, Comprising: The ultrafiltration membrane of an ultrafiltration apparatus is 1 nm-0.1 micrometer in pore diameters. It is characterized by having a porous membrane having

Invention of the cellulose ester film of Claim 9 is manufactured by the manufacturing method of the cellulose ester film of Claims 1-8, and the foam failure on a film is 2 or less per 1 m < ² > film, It is characterized by the above-mentioned. Yes.

The dope is passed through a filtration device equipped with a filter medium, and then cast on a support, and a cellulose ester film is produced by a solution casting film forming method, and the inside of the filtration device is filled with the dope. When performing, the inside of a filtration apparatus is pressure-reduced, for example to -50 kPa--150 kPa, It is characterized by using the filtration apparatus with which the dope was inject | poured and filled from the exit side of the filtration apparatus.

  The invention of the method for producing a cellulose ester film according to claim 1 is a solution casting film forming method in which a dope in which a cellulose ester is dissolved is passed through a main filtration device equipped with a filter medium and then cast on a support. A cellulose ester film is produced by the above-mentioned method, and an ultrafiltration device connected by piping to the main filtration device is provided side by side, and when the dope is initially filled in the main filtration device, a predetermined casting is performed. The dope having a high viscosity for use is diluted with a solvent to lower the viscosity, and then injected into the main filtration device and initially filled, thereby expelling air in the main filtration device and bubbles in the filter medium. In this way, when the dope having a reduced viscosity is injected into the main filtration device, the low-viscosity dope is easily penetrated into the filter medium, spreads to every corner of the filter medium, and can expel bubbles inside the filter medium. Next, the low viscosity dope discharged from the main filtration device is introduced into the ultrafiltration device, the solvent is separated and removed by the ultrafiltration membrane in the ultrafiltration device, and the dope is concentrated to a predetermined high viscosity, A predetermined high viscosity dope discharged from the ultrafiltration device is circulated to the main filtration device, and then the main filtration device after completion of initial filling is used to cast the dope having a predetermined high viscosity for casting. Film formation is performed. According to the present invention, it is possible to reliably suppress the generation rate of foreign matters due to foam failure occurring in the cellulose ester film in the dope filtration process, and to produce a cellulose ester film free from the generation of foreign matters. The effect that it is excellent also in the property is produced.

  In the invention of claim 2, an ultrafiltration device is interposed in the dope flow path between the main filtration device and the casting die, and when the dope is initially filled in the main filtration device, a predetermined casting is used. A dope having a low viscosity added to a dope having a high viscosity is injected into the main filtration device and initially filled, thereby pursuing air in the main filtration device and bubbles in the filter medium. In this way, when the dope having a reduced viscosity is injected into the main filtration device, the low-viscosity dope is easily penetrated into the filter medium, spreads to every corner of the filter medium, and can expel bubbles inside the filter medium. Next, the low viscosity dope discharged from the main filtration device is introduced into the ultrafiltration device, the solvent is separated and removed by the ultrafiltration membrane in the ultrafiltration device, and the dope is concentrated to a predetermined high viscosity, A predetermined high-viscosity dope discharged from the ultrafiltration apparatus is introduced into a casting die, and thereafter, the main filtration apparatus having been initially filled is used to flow the dope with a predetermined high viscosity for casting. The film forming is performed. According to the present invention, it is possible to reliably suppress the generation rate of foreign matters due to foam failure occurring in the cellulose ester film in the dope filtration process, and to produce a cellulose ester film free from the generation of foreign matters. The effect that it is excellent also in the property is produced.

  The invention of claim 3 is provided with an ultrafiltration device connected by piping to the main filtration device, and in advance in the dope preparation kettle, 2 to 20 times the solvent contained in the predetermined casting dope The low-viscosity dope containing the above solvent is prepared, and when the dope is initially filled in the main filtration device, the low-viscosity dope is injected into the main filtration device to initially fill the air in the main filtration device. And expelling bubbles inside the filter medium. As described above, when the low viscosity dope is injected into the main filtration device, the low viscosity dope is easily permeated into the filter medium, spreads to every corner of the filter medium, and can expel bubbles inside the filter medium. Next, the low viscosity dope discharged from the main filtration device is introduced into the ultrafiltration device, the solvent is separated and removed by the ultrafiltration membrane in the ultrafiltration device, and the dope is concentrated to a predetermined high viscosity, A predetermined high viscosity dope discharged from the ultrafiltration device is circulated to the main filtration device, and then the main filtration device after completion of initial filling is used to cast the dope having a predetermined high viscosity for casting. Film formation is performed. According to the present invention, it is possible to reliably suppress the generation rate of foreign matters due to foam failure occurring in the cellulose ester film in the dope filtration process, and to produce a cellulose ester film free from the generation of foreign matters. The effect that it is excellent also in the property is produced.

  In the invention of claim 4, the ultrafiltration device is interposed in the dope flow path between the main filtration device and the casting die, and the solvent contained in the predetermined casting dope is previously prepared in the dope preparation kettle. A low-viscosity dope containing 2 to 20 times the solvent is prepared, and when the dope is initially filled in the main filtration device, the low-viscosity dope is injected into the main filtration device to initially fill the main filtration device. It expels air inside the device and bubbles inside the filter medium. As described above, when the low viscosity dope is injected into the main filtration device, the low viscosity dope is easily permeated into the filter medium, spreads to every corner of the filter medium, and can expel bubbles inside the filter medium. Next, the low viscosity dope discharged from the main filtration device is introduced into the ultrafiltration device, the solvent is separated and removed by the ultrafiltration membrane in the ultrafiltration device, and the dope is concentrated to a predetermined high viscosity, A predetermined high-viscosity dope discharged from the ultrafiltration apparatus is introduced into a casting die, and thereafter, the main filtration apparatus having been initially filled is used to flow the dope with a predetermined high viscosity for casting. The film forming is performed. According to the present invention, it is possible to reliably suppress the generation rate of foreign matters due to foam failure occurring in the cellulose ester film in the dope filtration process, and to produce a cellulose ester film free from the generation of foreign matters. The effect that it is excellent also in the property is produced.

  In the invention of claim 5, an ultrafiltration device connected by piping to the main filtration device is provided side by side, and when the dope is initially filled in the main filtration device, the solvent is first injected into the main filtration device. By initially filling, bubbles inside the filter medium of the main filtration device are expelled. As described above, when the solvent is injected into the main filtration device, the solvent has a very low viscosity, so that the solvent is easily permeated into the filter medium, spreads to every corner of the filter medium, and can expel bubbles inside the filter medium. Next, a dope having a predetermined high viscosity for casting is introduced into the main filtration device, and a solvent discharged from the main filtration device and a low-viscosity dope diluted therein are introduced into the ultrafiltration device. The solvent is separated and removed by the ultrafiltration membrane in the apparatus, the dope is concentrated to a predetermined high viscosity, the predetermined high viscosity dope discharged from the ultrafiltration apparatus is circulated to the main filtration apparatus, and then the initial Casting film formation is performed with a dope having a predetermined high viscosity for casting using the main filtration device that has been filled. According to the present invention, it is possible to reliably suppress the generation rate of foreign matters due to foam failure occurring in the cellulose ester film in the dope filtration process, and to produce a cellulose ester film free from the generation of foreign matters. The effect that it is excellent also in the property is produced.

  In the invention of claim 6, when an ultrafiltration device is interposed in the dope flow path between the main filtration device and the casting die and the dope is initially filled in the main filtration device, the solvent is first added. By injecting into the filtration device and initial filling, bubbles inside the filter medium of the main filtration device are expelled. As described above, when the solvent is injected into the main filtration device, the solvent has a very low viscosity, so that the solvent is easily permeated into the filter medium, spreads to every corner of the filter medium, and can expel bubbles inside the filter medium. Next, a dope having a predetermined high viscosity for casting is introduced into the main filtration device, and a solvent discharged from the main filtration device and a low-viscosity dope diluted therein are introduced into the ultrafiltration device. The solvent is separated and removed by the ultrafiltration membrane in the apparatus, the dope is concentrated to a predetermined high viscosity, the predetermined high viscosity dope discharged from the ultrafiltration apparatus is introduced into the casting die, and then, Casting film formation is performed by using a dope having a predetermined high viscosity for casting using the main filtration apparatus in which the initial filling is completed. According to the present invention, it is possible to reliably suppress the generation rate of foreign matters due to foam failure occurring in the cellulose ester film in the dope filtration process, and to produce a cellulose ester film free from the generation of foreign matters. The effect that it is excellent also in the property is produced.

  Invention of Claim 7 is a manufacturing method of the cellulose-ester film as described in any one of Claims 1-6, Comprising: The filter medium of a main filtration apparatus is the collection particle diameter of 0.5-5 micrometers, and Since it has a drainage time of 10 to 25 sec / 100 ml, according to the present invention, the generation rate of foreign matters due to foam failure occurring in the cellulose ester film can be more reliably suppressed in the dope filtration step. There is an effect that it is possible to produce a cellulose ester film which is free from subsequent generation of foreign matter and excellent in productivity.

  Invention of Claim 8 is a manufacturing method of the cellulose-ester film as described in any one of Claims 1-6, Comprising: The ultrafiltration membrane of an ultrafiltration apparatus is 1 nm-0.1 micrometer in pore diameters. According to the present invention, it is possible to more reliably suppress the generation rate of foreign matters due to foam failure occurring in the cellulose ester film in the dope filtration step. There is an effect that it is possible to produce a cellulose ester film which is free from foreign matter and excellent in productivity.

Invention of the cellulose ester film of Claim 9 is manufactured by the manufacturing method of the cellulose ester film of Claims 1-8, and the foam failure on a film is 2 or less per 1 m < ² > film, this According to the invention, there is no generation of foreign matters due to foam failure in the cellulose ester film, and the cellulose ester film has an effect of being excellent in optical properties.

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

  FIG. 1 shows an embodiment of the first invention of the present invention. Referring to the figure, in the method for producing a cellulose ester film according to the present invention, a dope in which a cellulose ester is dissolved is passed through a main filtration device (1) provided with a filter medium, and then a support from a casting die (10). (11) A method for producing a cellulose ester film by casting on a solution casting method.

  In the method for producing a cellulose ester film of the first invention of the present invention, an ultrafiltration device (2) connected by a pipe (3) to the main filtration device (1) is provided side by side, and the main filtration device (1 When the dope having a predetermined high viscosity for casting is diluted with a solvent to lower the viscosity when the dope is initially filled in), the dope is injected into the main filtration device (1) and initially filled, The air in the main filtration device (1) and air bubbles inside the filter medium are expelled, and then the low-viscosity dope discharged from the main filtration device (1) is introduced into the ultrafiltration device (2), and the ultrafiltration device (2 ), The solvent is separated and removed by the ultrafiltration membrane, and the dope is concentrated to a predetermined high viscosity, and the predetermined high viscosity dope discharged from the ultrafiltration device (2) is supplied to the main filtration device (1). Circulate and then filter after the initial filling is completed and air bubbles are expelled Use main filtering device (1) having a, by doping with a high viscosity for a given casting, and performs casting film.

  FIG. 2 shows an embodiment of the second invention of the present invention. Referring to the figure, in the method for producing a cellulose ester film of the second invention of the present invention, an ultrafiltration device (2) is provided in a dope channel between a main filtration device (1) and a casting die (10). When the dope is initially filled in the main filtration device (1), a dope having a low viscosity by adding a solvent to a predetermined dope having a high viscosity for casting is added to the main filtration device (1). By injecting into the initial filtration, the air in the main filtration device (1) and bubbles inside the filter medium are expelled, and the low-viscosity dope discharged from the main filtration device (1) is then transferred to the ultrafiltration device (2). The solvent is separated and removed by the ultrafiltration membrane in the ultrafiltration device (2), the dope is concentrated to a predetermined high viscosity, and the predetermined high viscosity discharged from the ultrafiltration device (2). Of dope into the casting die (10), after which the initial filling is complete Use main filtration device having a filter medium bubbles were expelled to (1), by doping with a high viscosity for a given casting, and performs casting film.

  FIG. 3 shows an embodiment of the third invention of the present invention. Referring to the figure, the method for producing a cellulose ester film of the third invention of the present invention has an ultrafiltration device (2) connected by piping to the main filtration device (1), and is provided in advance. In the dope preparation kettle, a low-viscosity dope containing a solvent 2 to 20 times the solvent contained in a predetermined casting dope is prepared, and when the dope is initially filled in the main filtration device (1), By injecting the low viscosity dope into the main filtration device (1) and initially filling it, the air in the main filtration device (1) and the bubbles inside the filter medium are expelled, and then the low viscosity discharged from the main filtration device (1). The dope is introduced into the ultrafiltration device (2), the solvent is separated and removed by the ultrafiltration membrane in the ultrafiltration device (2), and the dope is concentrated to a predetermined high viscosity. (2) Dough with predetermined high viscosity discharged from Is circulated to the main filtration device (1), and then the dope having a predetermined high viscosity for casting is used by using the main filtration device (1) including the filter medium from which the initial filling is completed and the bubbles are expelled. Then, casting film formation is performed.

  FIG. 4 shows an embodiment of the fourth invention of the present invention. Referring to the figure, the method for producing a cellulose ester film of the fourth invention of the present invention has an ultrafiltration device (2) interposed in the dope flow path between the main filtration device (1) and the casting die. In addition, in the dope preparation pot, a low-viscosity dope containing a solvent 2 to 20 times the solvent contained in the predetermined casting dope is prepared in advance, and the dope is initially filled in the main filtration device (1). At this time, the low-viscosity dope is injected into the main filtration device (1) and initially filled to expel air in the main filtration device (1) and bubbles in the filter medium, and then from the main filtration device (1). The discharged low viscosity dope is introduced into the ultrafiltration device (2), the solvent is separated and removed by the ultrafiltration membrane in the ultrafiltration device (2), and the dope is concentrated to a predetermined high viscosity, A predetermined high-viscosity drain discharged from the ultrafiltration device (2). Is introduced into a casting die, and thereafter, by using a main filtration device (1) including a filter medium in which initial filling is completed and air bubbles are expelled, by a dope having a predetermined high viscosity for casting, Casting film formation is performed.

  Next, referring to FIG. 1 above, the method for producing a cellulose ester film of the fifth invention of the present invention is provided with an ultrafiltration device (2) connected by piping to the main filtration device (1). When the dope is initially filled in the main filtration device (1), first, a solvent is injected into the main filtration device (1) to initially fill the bubbles, so that air bubbles inside the filter medium of the main filtration device (1) are obtained. Then, a dope having a predetermined high viscosity for casting is introduced into the main filtration device (1), and the solvent discharged from the main filtration device (1) and the low-viscosity dope diluted therein are ultrafiltered. Introduced into the device (2), the solvent is separated and removed by the ultrafiltration membrane in the ultrafiltration device (2), the dope is concentrated to a predetermined high viscosity, and discharged from the ultrafiltration device (2). Circulates the specified high viscosity dope to the main filtration device (1) Then, using the main filtration device (1) provided with the filter medium from which the initial filling is completed and the bubbles are expelled, the casting film is formed with a dope having a predetermined high viscosity for casting. is there.

  Further, referring to FIG. 2 described above, the method for producing a cellulose ester film of the sixth invention of the present invention uses an ultrafiltration device (2) in the dope flow path between the main filtration device (1) and the casting die. When the dope is initially filled in the main filtration device (1), the filter medium of the main filtration device (1) is first filled by injecting the solvent into the main filtration device (1). The internal bubbles were expelled, and then a dope having a predetermined high viscosity for casting was introduced into the main filtration device (1), and the solvent discharged from the main filtration device (1) and the low viscosity dope diluted therein were added. Introduced into the ultrafiltration device (2), the solvent is separated and removed by the ultrafiltration membrane in the ultrafiltration device (2), the dope is concentrated to a predetermined high viscosity, and the ultrafiltration device (2 ) Introduce the dope with the predetermined high viscosity discharged from Uses the primary filtration device having a filter medium initial filling bubbles completed is expelled (1), by doping with a high viscosity for a given casting, and performs casting film.

  Below, the manufacturing method of the cellulose-ester film of this invention is demonstrated in detail.

  As the cellulose ester used in the method of the present invention, a cellulose ester synthesized from cotton linter, a cellulose ester synthesized from wood pulp, and a cellulose ester synthesized from other raw materials can be used alone or in combination.

  As the cellulose ester used in the present invention, a lower fatty acid ester of cellulose is preferably used.

  The lower fatty acid in the lower fatty acid ester of cellulose ester means a fatty acid having 6 or less carbon atoms, such as cellulose acetate, cellulose propionate, cellulose butyrate, etc., and JP-A-10-45804, 8 Examples of lower fatty acid esters of cellulose include mixed fatty acid esters such as cellulose acetate propionate and cellulose acetate butyrate described in Japanese Patent No. -231761 and US Pat. No. 2,319,052.

  As a measuring method of the substitution degree of the acyl group of a cellulose ester, it can implement according to ASTM-D-817-96.

  Among the above fatty acids, cellulose acetate and cellulose acetate propionate are preferably used. In the case of the cellulose ester film of the present invention, those having a polymerization degree of 250 to 400 are particularly preferably used from the viewpoint of film strength.

  In the cellulose ester film of the present invention, a cellulose ester having a total acyl group substitution degree of 2.5 to 3.0 is preferably used, and a cellulose ester having a total acyl group substitution degree of 2.55 to 2.85 is particularly preferable. Used. When the total acyl group substitution degree is 2.55 or more, the mechanical strength of the film increases, and when it is 2.85 or less, the solubility of the cellulose ester is improved and the generation of foreign substances is more preferable.

  When used as a polarizing plate protective film, cellulose acetate is more preferable, and a molecular weight distribution Mw / Mn obtained by dividing the weight average molecular weight Mw by the number average molecular weight Mn is more preferably 1.8 to 3.0.

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

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

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

  In the step of dissolving the cellulose ester resin, the recycled material of the cellulose ester film may be used together with the cellulose ester resin. The use ratio of the recycled material is preferably 0 to 70% by weight, more preferably 10 to 50% by weight, and most preferably 20 to 40% by weight based on the solid content of the prescription value such as the main dope. It is preferable to set the amount within the above range because the greater the amount of recycled material used, the better the filterability, and the smaller the amount of recycled material used, the better the slipperiness.

  Recycled material is a finely pulverized cellulose ester film, which is generated when the cellulose ester film is formed, and is obtained by cutting out both sides of the film, or by using a cellulose film raw material that has been speculated out of scratches. Is done.

  When the recycled material is used, the additives contained in the cellulose ester film such as ultraviolet absorbers and plasticizers described later are reduced in accordance with the amount used, and the final cellulose ester film composition becomes the design value. It is necessary to make adjustments.

  In the method for producing a cellulose ester film according to the present invention, fine particles are added in a step of dissolving a cellulose ester resin in a main solvent, and after the addition, the mixture is dissolved and mixed at a temperature equal to or higher than the boiling point of the main solvent.

  As fine particles used in the present invention, examples of inorganic compounds include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, and hydrated calcium silicate. Mention may be made of aluminum silicate, magnesium silicate and calcium phosphate. As the fine particles, those containing silicon are preferable in terms of low turbidity, and silicon dioxide is particularly preferable. The fine particles of silicon dioxide preferably have a primary average particle diameter of 20 nm or less and an apparent specific gravity of 70 g / liter or more. The average diameter of primary particles is more preferably 5 to 16 nm, further preferably 5 to 12 nm. A smaller primary particle average diameter is preferred because haze is low. The apparent specific gravity is preferably 90 to 200 g / liter or more, more preferably 100 to 200 g / liter or more. A higher apparent specific gravity is preferable because a high-concentration dispersion can be produced, and haze and aggregates are improved.

The amount of fine particles added is preferably 0.02 to 1.0 g, more preferably 0.03 to 0.3 g, and most preferably 0.08 to 0.2 g per 1 m ² .

  For example, the amount of silicon dioxide fine particles added to the cellulose ester is preferably 0.01 to 5.0% by weight, more preferably 0.05 to 1.0% by weight of the silicon dioxide fine particles relative to the cellulose ester. 1 to 0.6% by weight is most preferred. The larger the added amount, the better the dynamic friction coefficient, and the smaller the added amount, the less aggregates.

  The fine particles of silicon dioxide are commercially available under the trade names of, for example, Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, TT600 (manufactured by Nippon Aerosil Co., Ltd.). . Zirconium oxide fine particles are commercially available, for example, under the trade names Aerosil R976 and R811 (manufactured by Nippon Aerosil Co., Ltd.), and can be used.

  In the method for producing a cellulose ester film according to the present invention, the fine particles are preferably silicon dioxide fine particles. This is because silicon dioxide (silica) fine particles, which are generally known to have an effect on viscosity depending on temperature, are not preferred to be stirred and mixed above the boiling point of the solvent after addition. In the invention, by adding a silicon dioxide (silica) fine particle during the dissolution step of the cellulose ester resin, preferably in the middle of adding and dissolving the cellulose ester resin to the main solvent, it is conventionally a shock when adding fine particles in-line to the dope. It is possible to produce a cellulose ester film that is extremely effective in preventing the occurrence of foreign matter failure during the production of cellulose ester, which is considered to be caused by agglomeration, is free of foreign matter, and has excellent productivity. it can.

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

  Among these, Aerosil 200V and Aerosil R972V are fine particles of silicon dioxide having a primary average particle diameter of 20 nm or less and an apparent specific gravity of 70 g / liter or more, and the coefficient of friction is maintained while keeping the turbidity of the optical film low. It is particularly preferable because it has a great effect of reducing the effect.

  Here, it is preferable to carry out the dissolution and mixing of the fine particles in the cellulose ester resin dissolving step at a temperature not lower than the boiling point of the main solvent and not higher than the boiling point + 50 ° C. Thus, by regulating the temperature of the dissolution and mixing of the fine particles in the cellulose ester-based resin dissolution step to the temperature of the boiling point of the main solvent + 50 ° C. or less, the foreign matter generation rate can be reliably suppressed in the dope dissolution and mixing step. it can.

  Moreover, it is preferable to carry out the dissolution and mixing of the fine particles in the cellulose ester-based resin dissolution step for a period of 60 minutes to 300 minutes. Thus, by defining the time for dissolving and mixing the fine particles in the cellulose ester-based resin dissolving step, there is no deterioration of the coefficient of variation (distribution) of the fine particles in the cellulose ester film, and it is also preferable from the viewpoint of production suitability.

  Further, the fine particles added in the dissolution step of the cellulose ester resin are added during the addition of the cellulose ester resin to the dissolution vessel or after the addition until the cellulose ester resin is completely dissolved in the dissolution vessel. Is preferred. Thus, by defining the timing of addition of the fine particles in the cellulose ester-based resin dissolution step, the foreign matter generation rate due to the addition of the fine particles contained in the cellulose ester resin solution (dope) can be reduced to the dope dissolution and mixing step. In this case, the burden on the filter in the subsequent filtration step is greatly reduced, no foreign matter is generated, and the productivity is excellent.

  In the method for producing a cellulose ester film of the present invention, a dispersion of fine particles is prepared in advance, and this fine particle dispersion is added in a step of dissolving the cellulose ester resin in the main solvent. Dissolve and mix at temperature.

  As the solvent used when dispersing the fine particles, a solvent used in film formation of cellulose ester can be used. In particular, alcohol is preferable, and examples thereof include methanol, ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol, tert-butanol and the like having 1 to 8 carbon atoms.

  The concentration of the fine particles when the fine particles are mixed with a solvent and dispersed is preferably 5 to 30% by weight, more preferably 8 to 25% by weight, and most preferably 10 to 15% by weight. The higher the fine particle concentration in the fine particle dispersion, the lower the liquid turbidity with respect to the amount added, which is preferable because haze and aggregates are improved.

  The concentration of the fine particles when the fine particles are dispersed by mixing a solvent and a small amount of resin is preferably 0.5 to 10% by weight, more preferably 1 to 5% by weight, and most preferably 1 to 3% by weight. The concentration of the resin is preferably 2 to 10% by weight, more preferably 3 to 7% by weight, and most preferably 4 to 6% by weight. This range is preferable because of excellent dispersibility of the fine particles. The above range is preferable because the smaller the content of the fine particles, the lower the viscosity and the easier the handling, and the higher the content of the fine particles, the smaller the addition amount and the easier the addition to the main dope.

  As the disperser for dispersing the fine particles, a normal disperser can be used. Dispersers can be broadly divided into media dispersers and medialess dispersers. For dispersion of fine particles, a medialess disperser is preferred because of low haze.

  Examples of the media disperser include a ball mill, a sand mill, and a dyno mill.

Examples of the medialess disperser include an ultrasonic type, a centrifugal type, and a high pressure type. In the present invention, a high pressure disperser is preferable. The high pressure dispersion device is a device that creates special conditions such as high shear and high pressure by passing a composition in which fine particles and a solvent are mixed at high speed through a narrow tube. It is preferable that the maximum pressure condition inside the apparatus is 100 kgf / cm ² or more in a thin tube having a tube diameter of 1 to 2000 μm, for example, by processing with a high-pressure dispersion apparatus. More preferably, it is 200 kgf / cm ² or more. At that time, it is preferable that the maximum reaching speed reaches 100 m / sec or more and the heat transfer speed reaches 100 kcal / hr or more.

  Examples of the high-pressure dispersion apparatus include an ultra-high pressure homogenizer (trade name: Microfluidizer) manufactured by Microfluidics Corporation, a nanomizer manufactured by Nanomizer, or Ultra Turrax, and other Manton Gorin type high-pressure dispersion apparatuses such as Izumi Hood. Examples include a homogenizer manufactured by Machinery, a product number UHN-01 manufactured by Sanwa Machinery Co., Ltd., and the like.

  For example, the content of silica (Si) in the fine particles contained in the cellulose ester film is determined by pretreating the completely dried cellulose ester film with a micro digest wet decomposition apparatus (sulfuric acid decomposition) and alkali melting, and then ICP-AES. It can be determined by performing analysis using an (inductively coupled plasma emission spectroscopic analyzer).

  In the method for producing a cellulose ester film of the present invention, the same resin as the cellulose ester resin is dissolved and mixed in the fine particle dispersion added in the dissolving step of the cellulose ester resin, and the solids ratio of the fine particle dispersion is dissolved. It is preferably 0.1 to 0.5 times the solid matter ratio of the cellulose ester-based resin solution (dope) dissolved in the process.

  As described above, the fine particle dispersion contains the cellulose ester in addition to the fine particles, which is preferable in that the viscosity of the dispersion is adjusted and the stagnation stability is excellent.

  Here, the same cellulose ester as the main dope can be used. Moreover, you may use a return material like main dope.

  In the method for producing a cellulose ester film of the present invention, an ultraviolet absorber is added to the dope of the cellulose ester resin.

  Here, the ultraviolet absorber is intended to improve durability by absorbing ultraviolet rays of 400 nm or less, and the transmittance at a wavelength of 380 nm is preferably 10% or less, more preferably 5%. % Or less, more preferably 2% or less.

  The ultraviolet absorbent used in the present invention is preferably an ultraviolet absorbent that is liquid at a temperature of 20 ° C. The use of a liquid ultraviolet absorber at a temperature of 20 ° C. is preferable since there is little change in the thickness direction retardation (Rt) value when the film is stretched.

  UV absorbers preferably used are benzotriazole-based UV absorbers and benzophenone-based UV absorbers that are highly transparent and excellent in preventing the deterioration of polarizing plates and liquid crystal elements, and have less unnecessary coloration. UV absorbers are particularly preferred.

  Specific examples of the ultraviolet absorber used in the present invention include, for example, 5-chloro-2- (3,5-di-sec-butyl-2-hydroxylphenyl) -2H-benzotriazole, (2-2H-benzotriazole -2-yl) -6- (linear and side chain dodecyl) -4-methylphenol, 2-hydroxy-4-benzyloxybenzophenone, 2,4-benzyloxybenzophenone, etc., and tinuvin 109, tinuvin 171 Tinuvin such as Tinuvin 234, Tinuvin 326, Tinuvin 327, and Tinuvin 328 are all commercially available from Ciba Specialty Chemicals and can be preferably used. Among these, Tinuvin 109 and Tinuvin 171 are ultraviolet absorbers that are liquid at a temperature of 20 ° C., and can be more preferably used.

  The cellulose ester film according to the present invention preferably contains two or more ultraviolet absorbers.

  The amount of UV absorber used is not uniform depending on the type of UV absorber, operating conditions, etc., but when the dry film thickness of the cellulose ester film is 30 to 200 μm, it is 0.5 to 4 with respect to the cellulose ester film. 0.0 wt% is preferable, and 0.6 to 2.0 wt% is more preferable.

  In addition, in the manufacturing method of the cellulose-ester film of this invention, an ultraviolet absorber may be added to main dope at the melt | dissolution process of a cellulose-ester type resin separately from microparticle dispersion liquid. In this case, it is preferable to add the ultraviolet absorber in the form of an additive liquid. Here, the additive liquid containing the ultraviolet absorber is a liquid containing the ultraviolet absorber and added to the main dope. It is preferable to contain 1 to 30% by weight of an ultraviolet absorber, more preferably 5 to 20% by weight, and most preferably 10 to 15% by weight. The above range is preferable because the content of the ultraviolet absorber is excellent in the solubility of the cellulose ester and the content of the ultraviolet absorber is small and the addition is easy.

  It is preferable that the ultraviolet absorbent addition liquid contains a cellulose ester in addition to the ultraviolet absorbent from the viewpoint of adjusting the viscosity of the addition liquid. The same cellulose ester as the main dope can be used. Moreover, you may use a return material like main dope.

  In the method of the present invention, a plasticizer, an antioxidant and the like are preferably added to the cellulose ester resin dope.

  Although it does not specifically limit as a plasticizer which can be used by this invention, In a phosphate ester type | system | group, a triphenyl phosphate (TPP), a biphenyl diphenyl phosphate (BDP), a tricresyl phosphate, a cresyl diphenyl phosphate, an octyl diphenyl phosphate , Trioctyl phosphate, tributyl phosphate, etc. Rate (EPEG), methyl phthalyl ethyl glycolate, butyl phthalyl butyl glycolate and the like can be used.

  The above plasticizers may be used in combination of two or more as required. By containing these plasticizers, a film having excellent dimensional stability and water resistance can be obtained, which is particularly preferable.

  In the present invention, in order to make the water absorption rate and the moisture content within a specific range, the preferable addition amount of the plasticizer is 12% by weight or less with respect to the cellulose ester. When two or more kinds of plasticizers are used in combination, the total amount of these plasticizers may be 12% by weight or less.

  In the optical film of the present invention, in addition to the plasticizer, an additive exhibiting the same action as the plasticizer can be contained. As these additives, for example, if it is a low molecular weight organic compound capable of plasticizing a cellulose ester film, the same effect as the plasticizer can be obtained. These components are not added for the purpose of directly plasticizing the film as compared with the plasticizer, but exhibit the same action as the plasticizer depending on the amount.

  The cellulose ester film according to the present invention can contain a compound comprising a polyhydric alcohol ester of an aliphatic polyhydric alcohol and one or more monocarboxylic acids. The content of the polyhydric alcohol ester with respect to the cellulose ester is 4.5 to 12.5% by weight, preferably 6 to 12% by weight, and more preferably 7 to 11% by weight.

  In the cellulose ester film of the present invention, the monocarboxylic acid is preferably a compound having an aromatic ring or a cycloalkyl ring in the molecule.

  In the cellulose ester film of the present invention, the aliphatic polyhydric alcohol is preferably 2-20.

  Thus, the use of a polyhydric alcohol ester greatly contributes to the ability to reduce the amount of conventional plasticizers.

  Next, the aliphatic polyhydric alcohol ester used in the present invention will be described. The aliphatic polyhydric alcohol ester is an ester of a dihydric or higher aliphatic polyhydric alcohol and one or more monocarboxylic acids.

(Aliphatic polyhydric alcohol)
The aliphatic polyhydric alcohol used in the present invention is a dihydric or higher alcohol represented by the following general formula (1).

R _1- (OH) n (1)
In the formula, R ₁ represents an n-valent aliphatic organic group, n represents a positive integer of 2 or more, and an OH group represents an alcoholic and / or phenolic hydroxyl group.

  Here, as the n-valent aliphatic organic group, an alkylene group (for example, methylene group, ethylene group, trimethylene group, tetramethylene group, etc.), an alkenylene group (for example, ethenylene group, etc.), an alkynylene group (for example, ethynylene group, etc.), Examples include cycloalkylene groups (for example, 1,4-cyclohexanediyl group) and alkanetriyl groups (for example, 1,2,3-propanetriyl group). The n-valent aliphatic organic group includes those having a substituent (for example, a hydroxy group, an alkyl group, a halogen atom, etc.).

  n is preferably from 2 to 20. Examples of preferable polyhydric alcohol include, for example, adonitol, arabitol, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propanediol, dipropylene glycol, tripropylene glycol, 1 , 2-butanediol, 1,3-butanediol, 1,4-butanediol, dibutylene glycol, 1,2,4-butanetriol, 1,5-pentanediol, 1,6-hexanediol, hexanetriol, Examples thereof include galactitol, mannitol, 3-methylpentane-1,3,5-triol, pinacol, sorbitol, trimethylolpropane, trimethylolethane, xylitol and the like. In particular, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, sorbitol, trimethylolpropane, and xylitol are preferable.

(Monocarboxylic acid)
In the present invention, the monocarboxylic acid in the polyhydric alcohol ester is not particularly limited, and known aliphatic monocarboxylic acid, alicyclic monocarboxylic acid, aromatic monocarboxylic acid and the like can be used. Use of an alicyclic monocarboxylic acid or aromatic monocarboxylic acid is preferable in terms of improving moisture permeability and retention.

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

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

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

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

  Examples of preferred aromatic monocarboxylic acids include those in which an alkyl group is introduced into the benzene ring of benzoic acid such as benzoic acid and toluic acid, and two or more benzene rings such as biphenylcarboxylic acid, naphthalenecarboxylic acid, and tetralincarboxylic acid. The aromatic monocarboxylic acid which has, or those derivatives can be mentioned. Benzoic acid is particularly preferable.

(Polyhydric alcohol ester)
The molecular weight of the polyhydric alcohol ester used in the present invention is not particularly limited, but is preferably 300 to 1500, and more preferably 350 to 750. The larger one is preferable in terms of retention, and the smaller one is preferable in terms of moisture permeability and compatibility with cellulose ester.

  In the present invention, the carboxylic acid in the polyhydric alcohol ester may be one kind or a mixture of two or more kinds. Moreover, all the OH groups in the polyhydric alcohol may be esterified, or a part of the OH groups may be left as they are. Preferably, it has 3 or more aromatic rings or cycloalkyl rings in the molecule.

  Examples of the polyhydric alcohol ester used in the present invention are shown below.

  In the present invention, as the polyhydric alcohol ester, trimethylolpropane tribenzoate (TMPTB), trimethylolpropane triacetate, trimethylolpropane tripropionate, dipropylene glycol dibenzoate, tripropylene glycol dibenzoate, 1,3-dibutylene Glycol dibenzoate, tetraethylene glycol dibenzoate, mixed ester of trimethylolpropane with acetic acid and benzoic acid, ester of trimethylolpropane with cyclohexanecarboxylic acid, mixed ester of trimethylolpropane with acetic acid and cyclohexanecarboxylic acid, 3- Esters of methylpentane-1,3,5-triol and cyclohexanecarboxylic acid, 3-methylpentane-1,3,5-triol and Esters of Kosan, esters of xylitol and benzoic acid, esters of xylitol and cyclohexanecarboxylic acid.

  In addition, the usage-amount of a polyhydric alcohol ester is preferable 4.5-12.5 weight% with respect to a cellulose ester, 6-12 weight% is further more preferable, Most preferably, it is 7-11 weight%.

  The cellulose ester film according to the present invention contains additives such as a plasticizer and an ultraviolet absorber in addition to the cellulose ester, the solvent, and the compound comprising the polyhydric alcohol ester.

  Additives such as compounds composed of polyhydric alcohol esters, plasticizers, UV absorbers, etc. can be mixed with a solvent in advance and dissolved or dispersed, and then added to the solvent before dissolving the cellulose ester, or the dope after dissolving the cellulose ester It may be thrown into.

  The polyhydric alcohol ester has a plasticizer function, and such a polyhydric alcohol ester and a conventional plasticizer can be used at the same time. In this case, the polyhydric alcohol ester can be used in the range of 4.5 to 12.5% by weight with respect to the cellulose ester as described above, but the total amount of the polyhydric alcohol ester and the plasticizer is It is preferable that it is 12.5 weight% or less in the weight% with respect to a cellulose ester. In this case, the amount of the plasticizer used is preferably 8.0% by weight or less based on the cellulose ester. Especially, it is preferable that the usage-amount of polyhydric alcohol ester is 7 weight% or more with respect to a cellulose ester, Furthermore, the usage-amount of a plasticizer shall be 5.5 weight% or less with respect to a cellulose ester. Is preferred. The reason is that the use of the conventional plasticizer can be reduced by using the polyhydric alcohol ester.

  The manufacturing method of the cellulose-ester film which is a preferable aspect of this invention is demonstrated in detail.

  The solution casting film forming method used in the method for producing a cellulose ester film of the present invention comprises the following dissolving step, filtration step, casting step, solvent evaporation step, peeling step, drying step and winding step. Each process will be described below.

  In the method for producing a cellulose ester film by the solution casting film forming method of the present invention, first, in the step of dissolving the main dope, the cellulose ester flakes are dissolved in the organic solvent mainly containing the above-mentioned good solvent in the kettle. The flakes are dissolved with stirring to form a dope.

  On the other hand, a fine particle dispersion to be added to the dope is prepared in a fine particle dispersion preparation kettle, and this fine particle dispersion is introduced into the main dope dissolving kettle and added to the cellulose ester resin solution (dope). In this case, the fine particles added in the dissolution step of the cellulose ester resin are added during or after the addition of the cellulose ester resin to the dissolution vessel and before the cellulose ester resin is completely dissolved in the dissolution vessel. Is preferred. In addition, the cellulose ester resin solution (dope) contains a plasticizer, an antioxidant, and the like.

  In the present invention, the solid content concentration in the dope is preferably adjusted to 15% by weight or more, particularly preferably 18 to 35% by weight.

  If the solid content concentration in the dope is too high, the viscosity of the dope becomes too high, and a sharkskin or the like may occur during casting to deteriorate the film flatness. Therefore, it is preferably 35% by weight or less.

  The dope viscosity is preferably adjusted to a range of 10 to 50 Pa · s.

  For dissolution, a method carried out at normal pressure, a method carried out below the boiling point of a preferred organic solvent (that is, a good solvent), a method carried out under pressure above the boiling point of the above-mentioned good solvent, a method carried out by a cooling dissolution method, and carried out at high pressure. There are various dissolution methods and the like. As a method of dissolving at a temperature higher than the boiling point of the good solvent and applying a pressure that does not boil, the foaming is suppressed by pressurizing to 0.11-1.50 MPa at 40.4-120 ° C. and in a short time. Can be dissolved.

  In the method of the present invention, additives such as an ultraviolet absorber, a plasticizer, and an antioxidant may be added together with a cellulose ester resin or a solvent during the preparation of the cellulose ester resin solution, or the solution is being prepared. Or after preparation.

The dope thus obtained is then guided to a filtration device and filtered. here,
There are several methods for the filtration. Filter filtration and disk filters are suitable for filtering high-viscosity cellulose ester dopes as in the present invention. System filtration is suitable from a productivity standpoint.

  Referring to FIG. 1 showing an embodiment of the first invention of the present invention, in the method for producing a cellulose ester film according to the present invention, the dope in which the cellulose ester is dissolved is transferred from a dissolving pot (not shown) to a stationary tank (stock tank). Once stored in (3). The main filtration device (1) is provided with an ultrafiltration device (2) connected by a pipe (8), and the dope flow from the stationary tank (3) to the main filtration device (1) In the middle of the pipe (4), a pump (5) and an open / close valve (13) are interposed, and a solvent injection pipe (7) from the dilution solvent tank (6) is provided downstream of the open / close valve (13). It is connected. The pipe (8) in which the ultrafiltration device (2) is attached to the main filtration device (1) includes an open / close valve (16) close to the outlet side of the main filtration device (1) and the main filtration device (1). An open / close valve (17) close to the inlet side is interposed. A solvent discharge pipe (18) for discharging the separated solvent is connected to the ultrafiltration device (2). The solvent separated in the ultrafiltration device (2) is sent from the solvent discharge pipe (18) to the solvent reuse return pipe (19) connected to the dilution solvent tank (6) for reuse. It is. The dope flow pipe (4) on the outlet side of the main filtration device (1) has an open / close valve (15) on the downstream side of the branch connection point of the pipe (8).

  And now, when the dope is initially filled in the main filtration device (1), the open / close valve (13) in the middle of the dope flow tube (4) is opened, and the dope flow tube on the outlet side of the main filtration device (1) (4) The on-off opening / closing valve (15) is closed. For the dope of the cellulose ester having a viscosity of, for example, 10 to 50 Pa · s sent from the stationary tank (3) through the flow pipe (4) by the operation of the pump (5), the solvent injection pipe (7) Open the on-off valve (14), inject a solvent from the dilution solvent tank (6), dilute the dope having a predetermined high viscosity for casting with a solvent, and reduce the viscosity to, for example, 1 to 9 Pa · s. The low-viscosity dope is injected into the main filtration device (1) and initially filled to expel air in the main filtration device (1) and bubbles in the filter medium (not shown). In this way, when the dope having a reduced viscosity is injected into the main filtration device (1), the low-viscosity dope is easily penetrated into the filter medium, spreads to every corner of the filter medium, and can expel bubbles inside the filter medium.

  Next, the low-viscosity dope discharged from the main filtration device (1) is introduced into the ultrafiltration device (2) through the pipe (8) and the open / close valve (16), and the limit in the ultrafiltration device (2) is introduced. The solvent is separated and removed by an outer filtration membrane (not shown), the dope is concentrated to a predetermined high viscosity, and the predetermined high viscosity dope discharged from the ultrafiltration device (2) is opened and closed with the pipe (8) and open / close It is circulated through the valve (17) to the main filtration device (1).

  In the initial filling stage of the main filtration device (1), it is preferable to open the on-off valve (14) of the solvent injection pipe (7) and continuously inject the solvent from the dilution solvent tank (6). When the air in the main filtration device (1) and the bubbles in the filter medium (not shown) are completely expelled, the open / close valve (14) of the solvent injection pipe (7) is closed, and the main filtration device (1). The low-viscosity dope after filling introduced in 1 is circulated through the ultrafiltration device (2) once to several times, and the dope is gradually concentrated to a predetermined high viscosity. Finally, a predetermined high-viscosity dope discharged from the ultrafiltration device (2) is circulated to the main filtration device (1).

  Then, open the open / close valve (15) in the middle of the dope flow pipe (4) on the outlet side of the main filtration device (1) and close the open / close valve (16) of the pipe (8) to the ultrafiltration device (2). By using the main filtration device (1) having the filter medium from which the initial filling is completed and the bubbles are expelled, the pump (5) is fed from the stationary tank (3) through the flow pipe (4). The dope having a predetermined high viscosity for casting is supplied to the casting die (10) from the casting pipe (4) after passing through the main filtration device (1), and the dope is fed to the casting pipe ( Casting is performed from 4) onto the support (11) to perform casting film formation.

  According to such a method of the present invention, when the main filtration device (1) is filled with the dope in the initial stage after the filter medium is newly loaded into the main filtration device (1), the inside of the main filtration device (1) It is possible to effectively prevent the formation of a dead space in which the dope is not sufficiently filled with, and conventionally, it is possible to prevent bubbles from being generated in the dope from the air pool accumulated in such a dead space. It is.

  According to such a cellulose ester film manufacturing apparatus of the present invention, it is possible to reliably suppress the generation rate of foreign matters due to foam failure occurring in the cellulose ester film in the dope filtration step, and the number of foreign matters due to foam failure is greatly increased. Thus, a cellulose ester film having excellent optical properties can be produced, and the productivity is also excellent.

  In the present invention, the filter medium of the main filtration device (1) is preferably filter paper. By using this filter paper, it is possible to remove only agglomerates such as fine particles that cause foreign matter and continuously filter the main dope with high viscosity, so there is no foreign matter failure, excellent raw material storage stability, and high speed Film formation becomes possible and productivity is improved.

  In the above, the collection particle diameter of the filter medium of the main filtration device (1) is measured in accordance with JIS Z 8901 and refers to the smallest particle diameter among particles that can be collected by 90% or more. Is.

  The collected particle diameter of the filter medium of the main filtration device (1) of the present invention is 0.5 to 5 μm, preferably 1 to 4 μm, and most preferably 2 to 3 μm. If the collected particle diameter of the filter medium is less than 0.5 μm, it is not preferable because fine particles that are not foreign matter are trapped and the filtration pressure rapidly increases, and if the collected particle size exceeds 5 μm, fine particles that cause foreign matter are collected. It is not preferable because it passes through the aggregates.

  Further, the drainage time of the filter medium of the main filtration device (1) is measured in accordance with JIS P 3801, using a Herzberg filtration rate tester, at a filtration surface of 10 cm 2, This is the time for filtering 100 ml of distilled water with a pressure of 0.98 kPa.

  In the present invention, the filtering time of the filter medium of the main filtration device (1) is 10 to 25 sec / 100 ml, preferably 10 to 20 sec / 100 ml, and most preferably 12 to 17 sec / 100 ml. Here, if the filtration time of the filter medium is less than 10 sec / 100 ml, the strength of the filter medium such as the filter paper is weak, so the filter paper is opened by the pressure, and foreign matter failure increases. Moreover, if the filtering time of the filter medium is longer than 25 sec / 100 ml, the initial pressure is high, the filtration resistance is too high, and high flow filtration cannot be performed continuously, and therefore the filter life is shortened. Therefore, it is not preferable.

  The filter particle collection particle size and drainage time of the main filtration device (1) are the fiber thickness of the filter paper, the selection of the fiber material such as material (cotton linter, wood pulp, rayon, polyester fiber, etc.), and the beating of the fiber material The degree of beating with a machine, addition of filler, etc., can be arbitrarily adjusted according to the filter paper manufacturing method.

  In the present invention, even if one filter paper of the main filtration device (1) is effective, it is more preferable to use about 2 to 7 filter papers because the filtration efficiency is increased. The same filter paper may be combined, or a filter paper having a small retained particle diameter may be combined inside. Moreover, it is preferable to use a guard filter paper for removing large dust on the outside. The guard filter paper has a large collection particle diameter of 20 μm or more, and a filter paper such as soft cotton can remove large dust without affecting the filtration pressure, and can prevent leakage of the main filtration device (1). In addition, a two-stage filtration in which the main dope solution that has been filtered once is filtered one more time is preferable because it has a great effect of removing aggregates.

In order to obtain a cellulose ester film with less foam failure (foreign matter) in the main filtration device (1) of the present invention, in particular, a filter paper having a collected particle diameter of 0.5 to 5 μm and a drainage time of 10 to 25 sec / 100 ml. In this case, it is preferable to form a film by filtering at a filtration pressure of 16 kg / cm ² or less. More preferably, the filtration pressure is 12 kg / cm ² or less, and more preferably, the filtration pressure is 10 kg / cm ² or less. The filtration pressure can be controlled by appropriately selecting the filtration flow rate and the filtration area.

  In the present invention, the ultrafiltration membrane of the ultrafiltration device (2) preferably has a porous membrane having a pore diameter of 1 nm to 0.1 μm. For example, an organic solvent-resistant membrane such as an ultrafiltration membrane (UF membrane) or a nanoparticle membrane made of Teflon (registered trademark) (Millipore, etc.) and polyimide hollow fiber (Nitto Denko) If so, the matting agent (silica particles) is not separated, and only the solvent (solvent) can be separated and recovered.

  With such an ultrafiltration membrane, the solvent can be reliably separated and removed from the initial filling low viscosity dope of the main filtration device (1), and the dope can be gradually concentrated to a predetermined high viscosity, Finally, a predetermined high-viscosity dope discharged from the ultrafiltration device (2) is circulated to the main filtration device (1), and then the main filter is provided with a filter medium in which initial filling is completed and air bubbles are expelled. Using the filtration device (1), casting film formation can be performed reliably.

  Next, referring to FIG. 2 showing an embodiment of the second invention of the present invention, the difference between the embodiment of the second invention and the embodiment of the first invention is that the main filtration device (1) and the casting are different. When the ultrafiltration device (2) is interposed in the dope channel between the die (10) and the dope is initially filled in the main filtration device (1), the dope has a predetermined high viscosity for casting. The dope, which has been reduced in viscosity by adding a solvent to the dope, is injected into the main filtration device (1) and initially filled, thereby expelling air in the main filtration device (1) and bubbles inside the filter medium, The low-viscosity dope discharged from the filtration device (1) is introduced into the ultrafiltration device (2), and the solvent is separated and removed by the ultrafiltration membrane in the ultrafiltration device (2). Concentrate to a viscosity and flow a predetermined high viscosity dope discharged from the ultrafiltration device (2). After the introduction into the die (10), the main filtration device (1) having the filter medium from which the initial filling has been completed and the air bubbles have been expelled is used. The point is that the film is formed.

  When a dope having a predetermined high viscosity for casting is added with a solvent to lower the viscosity and injected into the main filtration device (1) for initial filling, the dope flow on the outlet side of the main filtration device (1) The open / close valve (15) in the middle of the pipe (4) is closed, and the two open / close valves (22) and (23) of the circulation pipe (21) for the main filter (1) are opened, and the main filter (1) The low-viscosity dope passing through the inside is circulated 1 to several times through the circulation pipe (21) to completely expel air in the main filtration device (1) and bubbles inside the filter medium, and then the main filtration device ( 1) By opening the open / close valve (15) in the middle of the dope flow pipe (4) on the outlet side and closing the two open / close valves (22) and (23) of the circulation pipe (21) for the main filtration device (1) , Comprising a filter medium in which initial filling is completed and air bubbles are expelled The dope having a predetermined high viscosity for casting, which is sent from the stationary tank (3) to the inside of the flow pipe (4) by the operation of the pump (5), using the excess apparatus (1) After passing through the apparatus (1), the casting pipe (4) is supplied to the casting die (10), and the dope is cast from the casting pipe (4) onto the support (11) to produce the casting. It is what performs the film.

  Since the other points of the embodiment of the second invention are the same as those of the embodiment of the first invention, the same reference numerals are given to the same components in the drawings.

  Next, referring to FIG. 3 showing an embodiment of the third invention of the present invention, the difference between the embodiment of the third invention and the embodiment of the first invention is that the first dope preparation pot (30) in advance. , A low-viscosity dope containing a solvent 2 to 20 times the solvent contained in a predetermined casting dope is prepared, and the dope is initially filled in the main filtration device (1). Is injected into the main filtration device (1) and initially filled to expel air in the main filtration device (1) and bubbles inside the filter medium, and then limit the low-viscosity dope discharged from the main filtration device (1). Introduced into the outer filtration device (2), the solvent is separated and removed by the ultrafiltration membrane in the ultrafiltration device (2), the dope is concentrated to a predetermined high viscosity, and the ultrafiltration device (2) The dope with a predetermined high viscosity discharged from the main circulation device (1) is circulated. And then having a predetermined high viscosity for casting produced in the second dope preparation kettle (31) using the main filtration device (1) having the filter medium from which the initial filling is completed and the bubbles are expelled. The point is that casting is performed to form a film.

  When initially filling the main filtration apparatus (1) with a low-viscosity dope prepared in the first dope preparation kettle (30) and containing 2 to 20 times the solvent contained in the predetermined casting dope. The open / close valve (33) of the dope outflow pipe (32) on the first dope preparation kettle (30) side is opened, and the open / close valve (35) of the dope outflow pipe (34) on the second dope preparation kettle (31) side is opened. Keep closed. In addition, when the dope having a predetermined high viscosity for casting produced in the second dope preparation pot (31) is introduced into the main filtration device (1) after the initial filling, the second dope preparation pot (31) The open / close valve (35) of the dope outflow pipe (34) on the side is opened, and the open / close valve (33) of the dope outflow pipe (32) on the first dope preparation pot (30) side is closed.

  Since the other points of the embodiment of the third invention are the same as those of the embodiment of the first invention, the same reference numerals are given to the same components in the drawings.

  Further, referring to FIG. 4 showing an embodiment of the fourth invention of the present invention, the difference of the embodiment of the fourth invention from the embodiment of the third invention is that the main filtration device (1) and the casting die. The ultrafiltration device (2) is interposed in the dope channel between (10) and (10).

  Then, in the first dope preparation pot (30), a low-viscosity dope containing a solvent 2 to 20 times the solvent contained in the predetermined casting dope is prepared in advance, and the dope is put in the main filtration device (1). Is initially filled by injecting the low viscosity dope into the main filtration device (1), thereby expelling air in the main filtration device (1) and bubbles inside the filter medium.

  In addition, when injecting a low-viscosity dope prepared in advance in the first dope preparation kettle (30) into the main filtration device (1) for initial filling, the dope flow pipe (4) on the outlet side of the main filtration device (1) ) The on-off valve (15) is closed, and the two on-off valves (22) and (23) of the circulation pipe (21) for the main filtration device (1) are opened to pass through the main filtration device (1). The low-viscosity dope is circulated 1 to several times through the circulation pipe (21) to completely expel air in the main filtration device (1) and bubbles in the filter medium.

  Subsequently, the dope flow pipe (4) on the outlet side of the main filtration device (1) is opened and the open / close valve (15) is opened, and the two open / close valves (22) of the circulation pipe (21) for the main filtration device (1) ( 23), the low-viscosity dope discharged from the main filtration device (1) is introduced into the ultrafiltration device (2) immediately before the casting die (10), and the ultrafiltration device (2) The solvent is separated and removed by the ultrafiltration membrane, and the dope is concentrated to a predetermined high viscosity, and the predetermined high viscosity dope discharged from the ultrafiltration device (2) is introduced into the casting die (10). Thereafter, using the main filtration device (1) including the filter medium from which the initial filling is completed and the bubbles are expelled, the predetermined high viscosity for casting produced in the second dope preparation kettle (31) is obtained. Casting film formation is performed by the dope.

  Since the other points of the fourth embodiment are the same as those of the third embodiment, the same components are denoted by the same reference numerals in the drawings.

  Next, referring to FIG. 1 described above, the method for producing a cellulose ester film of the fifth invention of the present invention is provided with an ultrafiltration device (2) connected by piping to the main filtration device (1). When the dope is initially filled in the main filtration device (1), the solvent is first injected into the main filtration device (1) to perform the initial filling.

  As described above, when the solvent is injected into the main filtration device (1), the solvent has a very low viscosity, so that it is easily penetrated into the filter medium, reaches every corner of the filter medium, and can expel bubbles inside the filter medium.

  Next, a dope having a predetermined high viscosity for casting is introduced into the main filtration device (1), and the solvent discharged from the main filtration device (1) and the low-viscosity dope diluted therein are passed through the ultrafiltration device (2 ), The solvent is separated and removed by the ultrafiltration membrane in the ultrafiltration device (2), the dope is concentrated to a predetermined high viscosity, and discharged from the ultrafiltration device (2). A high viscosity dope is circulated to the main filtration device (1), and then the casting film is formed by using the dope having a predetermined high viscosity for casting by using the main filtration device (1) whose initial filling is completed. To do.

  According to the fourth aspect of the present invention, it is possible to reliably suppress the generation rate of foreign matters due to foam failure occurring in the cellulose ester film in the dope filtration step, and it is possible to produce a cellulose ester film without generation of foreign matters. Moreover, it is excellent in productivity.

  Moreover, the manufacturing method of the cellulose-ester film of 6th invention of this invention is an ultrafiltration apparatus in the dope flow path between the main filtration apparatus (1) and the casting die (10), if said FIG. 2 is referred. When the dope is initially filled in the main filtration device (1) with the (2) interposed, the solvent is first injected into the main filtration device (1) and initially filled, whereby the main filtration device (1 ), And the dope having a predetermined high viscosity for casting is introduced into the main filtration device (1), and the solvent discharged from the main filtration device (1) and the diluted low The viscosity dope is introduced into the ultrafiltration device (2), the solvent is separated and removed by the ultrafiltration membrane in the ultrafiltration device (2), the dope is concentrated to a predetermined high viscosity, and ultrafiltration is performed. A predetermined high viscosity dope discharged from the apparatus (2) is cast into a casting die (10 Then, using the main filtration device (1) having the filter medium from which the initial filling is completed and the bubbles are expelled, a casting film is formed by a dope having a predetermined high viscosity for casting. To do.

  In this invention, a cellulose-ester film can be manufactured through the casting process described below using the dope filtered by the specific method as mentioned above.

  The dope after filtration is introduced into a casting die (10), and a cellulose ester film is produced by a solution casting film forming method.

  In addition, it is preferable to store the dope after filtration once in a dope stock pot (not shown). Further, in the method of the present invention, it is preferable to contain an ultraviolet absorber in the fine particle dispersion. However, the present invention is not limited to this, and an ultraviolet absorber additive solution is prepared in advance in an additive solution dissolution vessel. The above-mentioned dope may be introduced into, for example, a static mixer, and an ultraviolet absorbent additive solution may be introduced before the static mixer, and the ultraviolet absorbent additive solution may be added in-line to the dope. The dope after the addition of the ultraviolet absorber addition liquid is introduced into the casting die (10).

  In the present invention, the casting dope thus produced is cast on the support (11) by the casting die (10). Here, the casting die (10) is preferably a pressure die that can adjust the slit shape of the die portion of the die and easily make the film thickness uniform. Examples of the pressure die include a coat hanger die and a T die, and any of them is preferably used.

  The support (11) is a support (11) having a mirror-finished stainless steel rotary drive endless belt or stainless steel rotary drive drum. The temperature of the support (11) can be cast at a temperature in the general temperature range of 0 ° C. to less than the boiling point of the solvent, but it is better to cast on the support (11) at 5 to 30 ° C. Since the dope is gelled and the peeling limit time can be increased, it is preferable that the dope is cast on a support (11) at 5 to 15 ° C. Here, the peeling limit time means the time during which the cast dope is on the support (11) at the limit of the casting speed at which a transparent and flat film can be continuously obtained. A shorter peeling limit time is preferable because of excellent productivity.

  In the drying step on the support (11), once the cast dope is gelled, the time from casting to peeling with the peeling roll (12) is taken as 100%, and within 30% from casting. The dope temperature is preferably set to 40 to 70 ° C., whereby the evaporation of the solvent is promoted, and it can be peeled off from the support (11) as soon as possible, and the peel strength is further increased. More preferably, the temperature is 55 to 70 ° C. Thereafter, this temperature is preferably maintained at 20% or more, and further preferably maintained at 40% or more.

  In the drying on the support (11), the web (20) may be peeled from the support (11) by a peeling roll (12) with a residual solvent amount of 60 to 150%. Since strength becomes small, it is preferable, and the residual solvent amount is more preferably 80 to 120%. The dope temperature at the time of peeling is preferably 0 to 30 ° C., because the base strength at the time of peeling can be increased and the base breakage at the time of peeling can be prevented, and 5 ° C. to 20 ° C. is more preferable.

  In the production of the cellulose ester film by the solution casting film forming method, the amount of residual solvent is represented by the following formula.

Residual solvent amount (% by weight) = {(M−N) / N} × 100
Here, M is the weight of the web (film) at an arbitrary point in time, and N is the weight of the film when the weight M is heat-treated at 115 ° C. for 1 hour.

  In the film drying step, the film peeled from the support (11) by the peeling roll (12) is further dried, and the residual solvent amount is 3% by weight or less, preferably 1% by weight or less, more preferably 0.5% by weight. The following is preferable for obtaining a film having good dimensional stability.

  After peeling, a tenter device that grips and conveys both ends of the web (20) with clips or pins and / or a drying device that alternately conveys the web (20) through conveyance rollers disposed in the drying device. Use to dry the web (20). For the liquid crystal display member, it is preferable to dry while maintaining the width by a tenter method in order to improve the dimensional stability. In particular, it is preferable to hold the width where there is a large amount of residual solvent immediately after peeling from the support (11) because the effect of improving dimensional stability is more exhibited.

  In particular, in the drying step after peeling from the support (11), the web (20) tends to shrink in the width direction due to evaporation of the solvent. Shrinkage increases with drying at higher temperatures. In order to improve the flatness of the finished film, it is preferable to dry while suppressing the shrinkage as much as possible. From this point, for example, the entire drying process or a part of the process as shown in Japanese Patent Application Laid-Open No. 62-46625 is clipped in the width direction while holding both ends of the web (20) in the width direction. The drying method / tenter method is preferred.

  The means for drying the film is not particularly limited, and is generally performed with hot air, infrared rays, a heating roll, microwaves, or the like. It is preferable to carry out with hot air in terms of simplicity. The drying temperature is preferably divided into 3 to 5 stages in the range of 40 to 150 ° C., and gradually increased, and it is more preferable to carry out in the range of 80 to 140 ° C. in order to improve the dimensional stability. .

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

  After the amount of residual solvent in the film after drying is 2% by weight or less, the cellulose ester resin film is wound into a roll by a winder, and the residual solvent amount is 0.4% by weight or less. A film having good stability can be obtained.

  The winder to be used may be a commonly used winder, and can be wound by a winding method such as a constant tension method, a constant torque method, a taper tension method, or a program tension control method with a constant internal stress.

  In order to stabilize the winding property, a so-called knurling process may be performed in which unevenness is imparted to both ends in the width direction of the cellulose ester-based resin film to make the ends bulky.

  When the ratio of the knurling height (a: μm) to the film thickness (d: μm) X (%) = (a / d) × 100, the range of X = 0 to 25% stabilizes the winding property. Good for.

  Preferably, it is 0 to 15%, more preferably 0 to 10%. From this range, when the knurling height ratio is large, the winding shape is likely to be deformed.

  In the present invention, the thickness of the cellulose ester-based resin film is generally 20 to 200 μm. However, it is desired to reduce the thickness and weight of a polarizing plate used in a liquid crystal display (LCD). Therefore, the thickness is preferably 20 to 65 μm, more preferably 30 to 60 μm, and still more preferably 35 to 50 μm. If it is thinner than this, the stiffness of the film will be reduced, so troubles due to the occurrence of wrinkles etc. are likely to occur in the polarizing plate production process, and if it is thicker than this, it will contribute to the thinning of the LCD Few.

  The cellulose ester film produced by the method of the present invention has a coefficient of variation (average particle size / standard deviation) of fine particles in a cross section of a cut piece of the cellulose ester film in the particle size measurement of fine particles using a transmission electron microscope. % Or less, preferably 30% or less. Thus, by further defining the coefficient of variation (average particle size / standard deviation) of the fine particles contained in the cellulose ester film, the distribution of the fine particles contained in the cellulose ester film is very good, and there is no generation of foreign matter. A cellulose ester film having excellent optical properties can be produced.

  Further, in the cellulose ester film of the present invention, the cross-section of the cut piece of the cellulose ester film is a particle size measurement of fine particles using a transmission electron microscope, the particle size measurement is a measurement of secondary fine particles, and the primary particle size is It is 20 nm or less, and the secondary particle diameter is 150 nm to 250 nm. Thus, by defining the primary particle diameter and the secondary particle diameter of the cellulose ester film to be specific, no foreign matter is generated, and the cellulose ester film is excellent in optical properties.

  Furthermore, it is preferable that the haze of the cellulose ester film according to the present invention is 0 to 0.5%, and the dynamic friction coefficient of the front and back surfaces is 0.5 to 0.7. Thus, by defining the haze of the cellulose ester film according to the present invention to a specific one, the transparency of the film is good, and by defining the dynamic friction coefficient of the front and back surfaces of the film to a specific one, slipping The film has good properties and the films are difficult to stick to each other, so that it is possible to improve the handling property during surface processing on these resin films and to stabilize the winding property.

  The cellulose ester film of the present invention is preferably used for a liquid crystal display member, specifically a protective film for a polarizing plate, from the viewpoint of good moisture permeability and dimensional stability. The cellulose ester film of the present invention is preferably used in a protective film for a polarizing plate that has strict requirements for both moisture permeability and dimensional stability.

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

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

  Thus, the obtained polarizing plate is provided in the one or both surfaces of a liquid crystal cell, and a liquid crystal display device is obtained using this.

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

  Furthermore, the liquid crystal display device using the polarizing plate protective film or retardation film comprising the cellulose ester film of the present invention can maintain stable display performance over a long period of time.

  The cellulose ester film of the present invention can also be used as a base material for an antireflection film or an optical compensation film.

  Examples of the present invention will be described below, but the present invention is not limited thereto.

Example 1
A cellulose triacetate film was produced by the method of the present invention.

(Preparation of dope)
Cellulose triacetate (acetylation degree 61.0%) 100 parts by weight Triphenyl phosphate (plasticizer) 8 parts by weight Methylene chloride 475 parts by weight Ethanol 50 parts by weight After heating up to 40 degreeC, it stirred at 40 degreeC for 4 hours, and melt | dissolved each composition. Thereafter, the stirring was stopped, the dope temperature was lowered to 35 ° C., and the dope temperature was introduced into the stationary tank (3) shown in FIG.

<Dope filtration>
Referring to FIG. 1, a filter press (FP) having a filtration area of 40 m ² was used as the main filtration device (1). A large number of filter papers (not shown) having a collected particle diameter of 2 μm and a drainage time of 20 sec / 100 ml as filter media were loaded in parallel.

  For the main filtration device (1), an ultrafiltration device (2) connected by a pipe (8) was provided. Here, as the ultrafiltration device (2), an ultrafiltration membrane having a molecular weight cut-off of 20,000 made by Membranex was used for MKUNIKIKA, ZCUFH3720, Mikuni ceramic filtration system membrane stylus.

  When the cellulose triacetate dope is initially filled in the main filtration device (1), the dope flow pipe (4) is opened and the open / close valve (13) is opened, and the main filtration device (1) outlet side dope flow pipe is opened. (4) The on-off opening / closing valve (15) is closed.

  The open / close valve of the solvent injection pipe (7) for the cellulose triacetate dope having a viscosity range of 20 Pa · s sent from the stationary tank (3) through the flow pipe (4) by the operation of the pump (5) (14) is opened, and a mixed solvent having the same mixing ratio of methylene chloride and ethanol is injected from the solvent tank for dilution (6), and the dope is diluted with the mixed solvent to reduce the viscosity to 5 Pa · s. The low-viscosity dope was injected into the main filtration device (1) and initially filled to expel air in the main filtration device (1) and bubbles in the filter medium (not shown). Thus, when the dope reduced in viscosity was injected into the main filtration device (1), the low-viscosity dope was easily penetrated into the filter medium, and it spread to every corner of the filter medium, thereby expelling bubbles inside the filter medium.

  Next, the low-viscosity dope discharged from the main filtration device (1) is introduced into the ultrafiltration device (2) through the pipe (8) and the open / close valve (16), and the limit in the ultrafiltration device (2) is introduced. The solvent is separated and removed by an outer filtration membrane (not shown), the dope is concentrated to a predetermined high viscosity of 20 Pa · s, and a predetermined high viscosity dope discharged from the ultrafiltration device (2) is piped ( It was circulated to the main filtration device (1) through 8) and the open / close valve (17).

  In the initial filling stage of the main filtration device (1), it is preferable to open the on-off valve (14) of the solvent injection pipe (7) and continuously inject the solvent from the dilution solvent tank (6). When the air in the main filtration device (1) and the bubbles in the filter medium (not shown) are completely expelled, the open / close valve (14) of the solvent injection pipe (7) is closed, and the main filtration device (1). The low-viscosity dope after filling introduced in 1 is circulated through the ultrafiltration device (2) once to several times, and the dope is gradually concentrated to a predetermined high viscosity of 20 Pa · s. Finally, a predetermined high-viscosity dope discharged from the ultrafiltration device (2) was circulated to the main filtration device (1).

  Then, open the open / close valve (15) in the middle of the dope flow pipe (4) on the outlet side of the main filtration device (1) and close the open / close valve (16) of the pipe (8) to the ultrafiltration device (2). By using the main filtration device (1) having the filter medium from which the initial filling is completed and the bubbles are expelled, the pump (5) is fed from the stationary tank (3) through the flow pipe (4). The dope having a predetermined high viscosity for casting is supplied to the casting die (10) from the casting pipe (4) after passing through the main filtration device (1), and the dope is fed to the casting pipe ( Cast from 4) onto a support (11) comprising an endless belt made of stainless steel. Then, after making it dry enough with a support body (11), the web (dope film | membrane) (20) was peeled and the cellulose triacetate film was produced by letting it pass through the drying zone comprised by many rolls.

<Evaluation of cellulose triacetate film>
About the cellulose triacetate film of Example 1 produced as described above, an on-line defect inspection machine (not shown) is installed immediately before the winding part of the belt casting film forming apparatus, and the number of foreign matters per 1 m ^{2 of} film is determined. It was two when measured.

Example 2
Although it implemented like the case of the said Example 1, the cellulose triacetate film was produced by the method of 2nd invention using the solution casting film forming apparatus shown to the flow sheet of FIG.

  In the second embodiment, the difference from the first embodiment is that an ultrafiltration device (2) is interposed in the dope channel between the main filtration device (1) and the casting die (10). It is in. Then, when the dope is initially filled in the main filtration device (1), the above-described embodiment of methylene chloride and ethanol from the dilution solvent tank (6) is added to the dope having a high casting viscosity of 20 Pa · s. By adding the same mixed solvent as the mixing ratio of 1 and reducing the viscosity to 5 Pa · s into the main filtration device (1) and initially filling the dope, the air in the main filtration device (1) And air bubbles inside the filter medium were expelled. Thus, when the dope reduced in viscosity was injected into the main filtration device (1), the low-viscosity dope was easily penetrated into the filter medium, and it spread to every corner of the filter medium, thereby expelling bubbles inside the filter medium.

  Next, the low-viscosity dope discharged from the main filtration device (1) is introduced into the ultrafiltration device (2), and the solvent is separated and removed by the ultrafiltration membrane in the ultrafiltration device (2). A predetermined high viscosity dope concentrated to a predetermined high viscosity of 20 Pa · s and discharged from the ultrafiltration device (2) is introduced into the casting die (10). Using the main filtration device (1) equipped with the filter medium that had been expelled, casting was performed with a dope having a high viscosity for casting of a predetermined 20 Pa · s.

  In addition, when the dope having a high viscosity for casting is added to the main filtration device (1) by adding the mixed solvent to lower the viscosity, the main filtration device (1) Close the open / close valve (15) in the middle of the dope flow pipe (4) on the outlet side, and open the two open / close valves (22) (23) of the circulation pipe (21) for the main filtration device (1). After the low-viscosity dope passing through the filtration device (1) is circulated 1 to several times through the circulation pipe (21) to completely expel air in the main filtration device (1) and bubbles in the filter medium. The dope flow pipe (4) on the outlet side of the main filtration device (1) is opened and the open / close valve (15) is opened, and the two open / close valves (22) and (23) of the circulation pipe (21) for the main filtration device (1) are opened. ), The initial filling was completed and the bubbles were expelled A casting height of a predetermined 20 Pa · s sent from the stationary tank (3) to the inside of the flow pipe (4) by the operation of the pump (5) using the main filtration device (1) provided with the material. After passing through the main filtration device (1), the dope having viscosity is supplied from the flow pipe (4) to the casting die (10), and the dope is fed from the flow pipe (4) onto the support (11). To produce a cellulose triacetate film.

<Evaluation of cellulose triacetate film>
About the cellulose triacetate film of Example 2 produced as mentioned above, it was 2 when the number of the foreign materials per 1 m < ² > of films was measured similarly to the case of the said Example 1. FIG.

Example 3
Although it implemented like the case of the said Example 1, the cellulose triacetate film was produced by the method of 3rd invention using the solution casting film forming apparatus shown to the flow sheet of FIG.

  Referring to FIG. 3, the difference between Example 3 and Example 1 is that in the first dope preparation pot (30), a solvent five times as much as the solvent contained in the predetermined casting dope is used. A low-viscosity dope of 0.5 Pa · s is prepared, and when the dope is initially filled in the main filtration device (1), this low-viscosity dope is injected into the main filtration device (1) and initially filled. Thus, the air in the main filtration device (1) and the bubbles inside the filter medium are expelled. . Here, when initially filling a low-viscosity dope prepared in the first dope preparation kettle (30) containing a solvent five times the solvent contained in the predetermined casting dope into the main filtration device (1). Open the open / close valve (33) of the dope outflow pipe (32) on the first dope preparation pot (30) side and open the open / close valve (35) of the dope outflow pipe (34) on the second dope preparation pot (31) side. Keep it closed.

  Next, the low-viscosity dope discharged from the main filtration device (1) is introduced into the ultrafiltration device (2), and the solvent is separated and removed by the ultrafiltration membrane in the ultrafiltration device (2). Concentrate and circulate the predetermined high-viscosity dope discharged from the ultrafiltration device (2) through the main filtration device (1) once to several times, and gradually concentrate the dope to a predetermined high viscosity of 20 Pa · s. Go. Finally, a predetermined high viscosity dope for casting of 20 Pa · s discharged from the ultrafiltration device (2) was circulated to the main filtration device (1).

  Then, open the open / close valve (15) in the middle of the dope flow pipe (4) on the outlet side of the main filtration device (1) and close the open / close valve (16) of the pipe (8) to the ultrafiltration device (2). By using the main filtration device (1) including the filter medium in which the initial filling is completed and the bubbles are expelled, the high viscosity for casting of 20 Pa · s produced in the second dope preparation kettle (31) is obtained. The dope is introduced into the main filtration device (1) after the initial filling. At this time, the open / close valve (35) of the dope outflow pipe (34) on the second dope preparation kettle (31) side is opened, The on-off valve (33) of the dope outflow pipe (32) on the preparation kettle (30) side is closed. The dope having a predetermined high viscosity for casting of 20 Pa · s produced in the second dope preparation kettle (31) sent through the feed pipe (4) by the operation of the pump (5) After passing through the apparatus (1), the dope is supplied from the flow pipe (4) to the casting die (10), and the dope is transferred from the flow pipe (4) onto the support (11) made of a stainless steel endless belt. The cellulose triacetate film was produced by casting.

<Evaluation of cellulose triacetate film>
About the cellulose triacetate film of Example 3 produced as mentioned above, it was 2 when the number of the foreign materials per 1 m < ² > film was measured similarly to the case of the said Example 1. FIG.

  Moreover, when the finished cellulose triacetate film was observed with a microscope for grainy foreign matter, no grainy foreign matter was found.

  Here, among the foreign substances, the so-called “grainy” foreign substances, in which the cellulose ester film is scattered as minute irregularities on the entire surface, are observed as white foreign substances due to the reflection of irradiation light, This is distinct from so-called bright spot foreign matter observed as a luminescence phenomenon. As described above, according to the method of the third invention of the present invention, it was found that the undissolved material is reduced by the cellulose triacetate dissolution and mixing under dilution, and the grainy foreign matter is improved.

Example 4
Although it carried out like the case of the said Example 3, the cellulose triacetate film was produced by the method of the 4th invention using the solution casting film forming apparatus shown to the flow sheet of FIG.

  Referring to FIG. 4, the difference between the fourth embodiment and the third embodiment is that an ultrafiltration device (2) is provided in the dope channel between the main filtration device (1) and the casting die (10). ). In addition, in the 1st dope preparation pot (30), the low viscosity dope of 0.5 Pa * s containing the solvent 5 times the solvent contained in predetermined | prescribed casting dope was produced previously, and main filtration apparatus (1 In the initial filling of the dope into), the low-viscosity dope was injected into the main filtration device (1) and initially filled to expel air in the main filtration device (1) and bubbles inside the filter medium.

  When the low-viscosity dope prepared in advance in the first dope preparation pot (30) is injected into the main filtration device (1) for initial filling, the dope flow pipe (4) on the outlet side of the main filtration device (1) ) The on-off valve (15) is closed, and the two on-off valves (22) and (23) of the circulation pipe (21) for the main filtration device (1) are opened to pass through the main filtration device (1). The low-viscosity dope was circulated 1 to several times through the circulation pipe (21) to completely expel air in the main filtration device (1) and bubbles in the filter medium.

  Subsequently, the dope flow pipe (4) on the outlet side of the main filtration device (1) is opened and the open / close valve (15) is opened, and the two open / close valves (22) of the circulation pipe (21) for the main filtration device (1) ( 23), the low-viscosity dope discharged from the main filtration device (1) is introduced into the ultrafiltration device (2) immediately before the casting die (10), and the ultrafiltration device (2) The solvent is separated and removed by an ultrafiltration membrane, and the dope is concentrated to a predetermined high viscosity of 20 Pa · s, and the predetermined high viscosity dope discharged from the ultrafiltration device (2) is cast into a casting die (10 After that, casting film formation was performed using the main filtration device (1) including the filter medium in which the initial filling was completed and the bubbles were expelled. At this time, the dope having a predetermined high viscosity for casting of 20 Pa · s produced in the second dope preparation kettle (31) sent through the feed pipe (4) by the operation of the pump (5). After passing through the main filtration device (1), the dope is supplied from the flow pipe (4) to the casting die (10), and the dope is fed from the flow pipe (4) to a support made of an endless belt made of stainless steel ( 11) The cellulose triacetate film was produced by casting on the top.

<Evaluation of cellulose triacetate film>
About the cellulose triacetate film of Example 4 produced as mentioned above, it was 2 when the number of the foreign material per 1 m < ² > film was measured similarly to the case of the said Example 1. FIG.

  Moreover, when the finished cellulose triacetate film was observed with a microscope for grainy foreign matter, no grainy foreign matter was found. Thus, according to the method of the 4th invention of this invention, it became clear by a cellulose triacetate melt | dissolution mixing under dilution that an undissolved substance reduces and it improves regarding a grain-like foreign material.

Example 5
Although it implemented like the case of the said Example 1, the cellulose triacetate film was produced by the method of 5th invention using the solution casting film forming apparatus shown to the flow sheet of FIG.

  In the fifth embodiment, the difference from the first embodiment is that when the dope is initially filled in the main filtration device (1), the opening / closing valve (14) of the solvent injection pipe (7) is first opened. In addition, a mixed solvent having the same mixing ratio of methylene chloride and ethanol from the dilution solvent tank (6) as in Example 1 is injected into the main filtration device (1) for initial filling.

  In this way, when only the solvent is injected into the main filtration device (1), the solvent has a very low viscosity, so that it can easily penetrate into the filter medium, reach every corner of the filter medium, and expel bubbles inside the filter medium. It was.

  Next, when the air in the main filtration device (1) and the bubbles in the filter medium (not shown) are completely expelled, the open / close valve (14) of the solvent injection pipe (7) is closed, and the main filtration device (1) The mixed solvent discharged is introduced into the ultrafiltration device (2) through the pipe (8) and the open / close valve (16), and the solvent is removed by the ultrafiltration membrane (not shown) in the ultrafiltration device (2). The cellulose triacetate dope having a viscosity range of 20 Pa · s sent from the stationary tank (3) through the flow pipe (4) by the operation of the pump (5) is removed from the main filtration device ( Introduced in 1). And the solvent discharged | emitted from these main filtration apparatuses (1) and the low viscosity dope diluted in this are introduce | transduced into an ultrafiltration apparatus (2), and a solvent is used by the ultrafiltration membrane in an ultrafiltration apparatus (2). Is separated and removed, the dope is concentrated, and the dope discharged from the ultrafiltration device (2) is circulated through the main filtration device (1) and the ultrafiltration device (2) one to several times to obtain a predetermined dope. Then, the dope having a predetermined high viscosity discharged from the ultrafiltration device (2) was circulated to the main filtration device (1).

  Then, open the open / close valve (15) in the middle of the dope flow pipe (4) on the outlet side of the main filtration device (1) and close the open / close valve (16) of the pipe (8) to the ultrafiltration device (2). By using the main filtration device (1) including the filter medium in which the initial filling with the solvent is completed and the bubbles are expelled, the pump (5) is operated by the operation of the pump (5) from the stationary tank (3). The dope having a predetermined high viscosity for casting is fed to the casting die (10) from the casting pipe (4) after passing through the main filtration device (1), and the dope is fed. A cellulose triacetate film was produced by casting from a tube (4) onto a support (11) comprising an endless belt made of stainless steel.

<Evaluation of cellulose triacetate film>
With respect to the cellulose triacetate film of Example 5 produced as described above, the number of foreign matters per 1 m ² of the film was measured and found to be 2.

Example 6
Although it implemented like the case of the said Example 1, the cellulose triacetate film was produced by the method of 6th invention using the solution casting film forming apparatus shown to the flow sheet of FIG.

  In the sixth embodiment, the difference from the first embodiment is that the ultrafiltration device (2) is interposed in the dope channel between the main filtration device (1) and the casting die (10). It was.

  In the sixth embodiment, the difference from the first embodiment is that when the dope is initially filled in the main filtration device (1), the opening / closing valve (14) of the solvent injection pipe (7) is first opened. In addition, a mixed solvent having the same mixing ratio of methylene chloride and ethanol from the dilution solvent tank (6) as in Example 1 is injected into the main filtration device (1) for initial filling.

  In this way, when only the solvent is injected into the main filtration device (1), the solvent has a very low viscosity, so that it can easily penetrate into the filter medium, reach every corner of the filter medium, and expel bubbles inside the filter medium. It was.

  Next, when the air in the main filtration device (1) and the bubbles in the filter medium (not shown) are completely expelled, the open / close valve (14) of the solvent injection pipe (7) is closed, and the main filtration device (1) The mixed solvent discharged is introduced into the ultrafiltration device (2), and the solvent is separated and removed by an ultrafiltration membrane (not shown) in the ultrafiltration device (2), while being removed from the stationary tank (3). A cellulose triacetate dope having a viscosity of 20 Pa · s sent through the flow pipe (4) by the operation of the pump (5) was introduced into the main filtration device (1). And the solvent discharged | emitted from these main filtration apparatuses (1) and the low viscosity dope diluted in this are introduce | transduced into an ultrafiltration apparatus (2), and a solvent is used by the ultrafiltration membrane in an ultrafiltration apparatus (2). Is removed, the dope is concentrated, and a high viscosity dope having a predetermined viscosity of 20 Pa · s discharged from the ultrafiltration device (2) is introduced into the casting die (10). The main filtration apparatus (1) having the filter medium from which bubbles have been expelled and the dope having a predetermined high viscosity for casting is used to perform casting film formation. At this time, the pump (5 After the passage through the main filtration device (1), the dope having the predetermined high viscosity for casting produced in the second dope preparation kettle (31) sent through the feed pipe (4) by the operation of The dope is supplied from the flow pipe (4) to the casting die (10). 4) consists of an endless belt made of stainless steel from the support (11) cast on, to prepare a cellulose triacetate film.

<Evaluation of cellulose triacetate film>
About the cellulose triacetate film of Example 6 produced as mentioned above, it was 2 when the number of the foreign materials per 1 m < ² > film was measured similarly to the case of the said Example 1. FIG.

Comparative Example 1
For comparison, the same procedure as in Example 1 is performed. However, the cellulose triacetate film is formed by a conventional method without using an ultrafiltration device (2) for the main filtration device (1). Manufactured.

About the cellulose triacetate film of Comparative Example 1 thus obtained, the number of foreign matters per 1 m ^{2 of} film was measured in the same manner as in Example 1 above, and it was 6.

The results of Examples 1 to 6 and Comparative Example 1 of the present invention are summarized in Table 1 below.

  As is apparent from the above results, according to Examples 1 to 6 of the present invention, the main filtration device (1) is doped in the initial stage after the filter material (filter paper) is newly loaded into the main filtration device (1). In the main filtration device (1), it is possible to effectively prevent the formation of dead space in which the dope is not sufficiently filled, and to prevent bubbles from forming in the dope. It was found that the generation rate of foreign matter due to foam failure occurring in the film can be reliably suppressed in the dope filtration process, and no foreign matter is generated thereafter, and the productivity is excellent.

  On the other hand, according to the conventional method of Comparative Example 1, the six foreign matters generated on the cellulose triacetate film were bubble failures caused by generation of bubbles. That is, after the filter paper is newly loaded into the main filtration device (1), in the initial stage of filling the inside of the filtration device with the dope, the dead space at the back of the device where the dope is not sufficiently filled in the main filtration device (1) Since the filter paper group loaded in the so-called air reservoir exists, these filter papers contain air that has not been scavenged, and the continuous filtration operation of the main filtration device (1). In this stage, it is considered that the air contained in such a group of filter paper becomes bubbles and is generated in the dope.

It is a flow sheet which shows the outline of the solution casting film forming apparatus which enforces the manufacturing method of the cellulose-ester film of 1st invention of this invention and 5th invention. It is a flow sheet which shows the outline of the solution casting film forming apparatus which enforces the manufacturing method of the cellulose-ester film of 2nd invention of this invention and 6th invention. It is a flow sheet which shows the outline of the solution casting film forming apparatus which enforces the manufacturing method of the cellulose-ester film of the 3rd invention of the present invention. It is a flow sheet which shows the outline of the solution casting film forming apparatus which enforces the manufacturing method of the cellulose ester film of the 4th invention of the present invention.

Explanation of symbols

1: Main filtration device 2: Ultrafiltration device 3: Static tank (stock tank)
4: Dope flow pipe 5: Pump 6: Dilution solvent tank 7: Solvent injection pipe 8: Pipe 10: Casting die 11: Support 12: Peeling roll 13: Open / close valve 14: Open / close valve 15: Open / close valve 16: Open / close valve 17: Open / close valve 18: Solvent discharge pipe 19: Solvent recycle return pipe 20: Web 21: Circulating pipe 22: Open / close valve 23: Open / close valve 30: First melting pot 31: Second melting pot 32: Dope outflow pipe 33: Open / close valve 34: Dope outflow pipe 35: Open / close valve

Claims (9)

  A method for producing a cellulose ester film by a solution casting film-forming method, in which a dope in which a cellulose ester is dissolved is passed through a main filtration device equipped with a filter medium and then cast on a support. When an ultrafiltration device connected by piping is connected to the device and the dope is initially filled in the main filtration device, the dope having a predetermined high viscosity for casting is diluted with a solvent to reduce the viscosity. By injecting the dope into the main filtration device and initially filling it, the air in the main filtration device and bubbles inside the filter medium are driven out, and then the low-viscosity dope discharged from the main filtration device is introduced into the ultrafiltration device. Then, the solvent is separated and removed by the ultrafiltration membrane in the ultrafiltration device, the dope is concentrated to a predetermined high viscosity, and the predetermined high viscosity dope discharged from the ultrafiltration device is supplied to the main filtration device. Circulate and that And use a primary filtration device initial filling is completed, by doping with a high viscosity for a given casting, and performing casting film, method for producing a cellulose ester film.   In this method, a dope in which cellulose ester is dissolved is passed through a main filtration device equipped with a filter medium, and then cast on a support through a casting die, and a cellulose ester film is produced by a solution casting film forming method. In addition, an ultrafiltration device is interposed in the dope channel between the main filtration device and the casting die, and when the dope is initially filled in the main filtration device, the dope having a predetermined high viscosity for casting is used. The dope, which has been reduced in viscosity by adding a solvent to it, is injected into the main filtration device and initially filled, thereby expelling air in the main filtration device and bubbles in the filter medium, and then discharging the low viscosity from the main filtration device. The dope is introduced into the ultrafiltration device, the solvent is separated and removed by the ultrafiltration membrane in the ultrafiltration device, the dope is concentrated to a predetermined high viscosity, and the predetermined high amount discharged from the ultrafiltration device is discharged. Guide the viscosity dope to the casting die And, thereafter, using a primary filtration device initial filling is completed, by doping with a predetermined casting for high viscosity, and performing casting film, method for producing a cellulose ester film.   A method for producing a cellulose ester film by a solution casting film-forming method, in which a dope in which a cellulose ester is dissolved is passed through a main filtration device equipped with a filter medium and then cast on a support. In addition to an ultrafiltration device connected by piping to the device, a low viscosity dope containing a solvent 2 to 20 times the solvent contained in a predetermined casting dope is prepared in advance in a dope preparation kettle. In addition, when the dope is initially filled in the main filtration device, the low-viscosity dope is injected into the main filtration device and initially filled to expel air in the main filtration device and bubbles in the filter medium. The low-viscosity dope discharged from the main filtration device is introduced into the ultrafiltration device, the solvent is separated and removed by the ultrafiltration membrane in the ultrafiltration device, the dope is concentrated to a predetermined high viscosity, Outer filter A predetermined high viscosity dope discharged from the apparatus is circulated to the main filtration apparatus, and then the casting film is formed by the dope having the predetermined high viscosity for casting using the main filtration apparatus after the initial filling is completed. A method for producing a cellulose ester film, which is performed.   In this method, a dope in which cellulose ester is dissolved is passed through a main filtration device equipped with a filter medium, and then cast on a support through a casting die, and a cellulose ester film is produced by a solution casting film forming method. In addition, an ultrafiltration device is interposed in the dope flow path between the main filtration device and the casting die, and 2 to 20 times the solvent contained in the predetermined casting dope in the dope preparation pot in advance. A low-viscosity dope containing a solvent is prepared, and when the dope is initially filled in the main filtration device, the low-viscosity dope is injected into the main filtration device and initially filled, whereby the air in the main filtration device and The air bubbles inside the filter medium are expelled, the low-viscosity dope discharged from the main filtration device is introduced into the ultrafiltration device, the solvent is separated and removed by the ultrafiltration membrane in the ultrafiltration device, and the dope is predetermined Up to high viscosity The dope having a predetermined high viscosity for casting is introduced by using the main filtration device after the initial filling is completed. The method for producing a cellulose ester film is characterized by performing casting film formation.   A method for producing a cellulose ester film by a solution casting film-forming method, in which a dope in which a cellulose ester is dissolved is passed through a main filtration device equipped with a filter medium and then cast on a support. When an ultrafiltration device connected by piping is connected to the device, and when the dope is initially filled in the main filtration device, first, the solvent is injected into the main filtration device and initially filled. Bubbles inside the filter medium of the filter device are driven out, and then a dope having a predetermined high viscosity for casting is introduced into the main filter device, and the solvent discharged from the main filter device and the low-viscosity dope diluted therein are excluded. Introduced into the filtration device, the solvent is separated and removed by the ultrafiltration membrane in the ultrafiltration device, the dope is concentrated to a predetermined high viscosity, and the predetermined high viscosity dope discharged from the ultrafiltration device is removed. Main filtration The cellulose ester film is produced by casting using a dope having a predetermined high viscosity for casting, using a main filtration apparatus that has been initially filled and then initially filled. .   In this method, a dope in which cellulose ester is dissolved is passed through a main filtration device equipped with a filter medium, and then cast on a support through a casting die, and a cellulose ester film is produced by a solution casting film forming method. Then, when an ultrafiltration device is interposed in the dope flow path between the main filtration device and the casting die, and when the dope is initially filled in the main filtration device, the solvent is first injected into the main filtration device. In the initial filtration, air bubbles inside the filter medium of the main filtration device are expelled, and then a dope having a predetermined high viscosity for casting is introduced into the main filtration device, and the solvent discharged from the main filtration device and diluted therein. The low-viscosity dope is introduced into the ultrafiltration device, the solvent is separated and removed by the ultrafiltration membrane in the ultrafiltration device, the dope is concentrated to a predetermined high viscosity, and discharged from the ultrafiltration device. Of a given high viscosity A loop is introduced into a casting die, and thereafter, using a main filtration device in which initial filling is completed, casting film formation is performed with a dope having a predetermined high viscosity for casting, A method for producing a cellulose ester film.   The filter medium of the main filtration device has a collected particle diameter of 0.5 to 5 µm and a drainage time of 10 to 25 sec / 100 ml, according to any one of claims 1 to 6, The manufacturing method of the cellulose-ester film of description.   The cellulose according to any one of claims 1 to 6, wherein the ultrafiltration membrane of the ultrafiltration device has a porous membrane having a pore diameter of 1 nm to 0.1 µm. A method for producing an ester film. A cellulose ester film produced by the method for producing a cellulose ester film according to claim 1, wherein the foam failure on the film is 2 or less per 1 m ^{2 of} film.

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