JP2005239916A - Cellulose ester film, method for producing the same, polarizing plate produced by using the film and liquid crystal display device produced by using the polarizing plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cellulose ester film for a protecting film of a polarizing plate of a liquid crystal display device, keeping the uniformity of various additives, having decreased scattering of optical properties and slipperiness in the film plane, free from spot defect possible to cause image defect, producible even by using a chlorine-free organic solvent taking consideration of environmental safety while keeping desired optical properties and film-to-film slipperiness and free from image defect. <P>SOLUTION: The cellulose ester film is produced by a solution casting film-forming method comprising the dispersion of fine particles of a mat agent in a solvent, mixing of the dispersion with a cellulose ester solution, casting of the mixed solution on a substrate, peeling of the web from the substrate after the initial drying of the solution and drying of the web. The particle in the cellulose ester film satisfies the relationship of 6≤b/c≤90 wherein b is the average particle diameter of the particles in the film and c is the average primary particle diameter of the fine particles. <P>COPYRIGHT: (C)2005,JPO&NCIPI

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, a method for producing the film, a polarizing plate using the film, and a liquid crystal display device using the polarizing plate. It is about.

  In recent years, liquid crystal display devices (LCDs) are used in various places, and high visibility when viewing images is demanded. In particular, polarizing plates and retardation plates used in LCDs are also like glass. There is a demand for flatness and no spot defects such as foreign matter. Further, in LCDs used outdoors such as car navigation systems and PDFs, it is necessary to include a UV absorber in the polarizing plate protective film in order to prevent the polarizer from deteriorating.

  By the way, cellulose triacetate (TAC) film is mainly used as a protective film for polarizing plates currently used in LCD, but it is used on the outermost surface especially by the spread of televisions and monitors and the enlargement of screens. In a film, high flatness is required, and when a spot defect is reached, the defect becomes an image defect, leading to a decrease in the quality of the LCD.

  In addition, resin films used in LCDs tend to stick to each other due to their transparency and smoothness, and fine particles are added to the film as a handling property when these resin films are formed or when they are surface processed. Without impairing the transparency of the film, it is slippery to improve handling and stabilize winding.

  The cellulose ester film is usually produced by a solution casting film forming method. That is, a film is produced by casting a cellulose ester dope (concentrated solution) from a casting die onto an endless support, and after the dope exhibits self-supporting properties, it is peeled off from the endless support. . In many cases, the film contains additives such as a matting agent, a plasticizer, and an ultraviolet absorber in addition to the cellulose ester. The matting agent is used to improve the slipperiness and adhesion resistance of the film formed, and the UV absorber is used to prevent deterioration of the polarizing plate, for example, when used for the polarizing plate. The These components are usually mixed together when preparing the dope.

  In particular, with the thinning of the cellulose ester film, the film is deformed in the winding process, and the film is stuck for a long time with the film wound long. May occur. And when such a film is used in the manufacturing process of a polarizing plate, the part which the films adhered will deform | transform, and it will become a cause which will produce a coating nonuniformity in the case of a bonding nonuniformity with a polarizer, and a coating process.

Here, the prior patent documents related to the cellulose ester film used for the conventional protective film for polarizing plate include the following.
In JP-A-2001-151936, as a method for preventing adhesion between films without deteriorating light transmittance, silicon dioxide fine particles having an average particle diameter of 0.5 μm to 1.0 μm are set to 0.000. A cellulose triacetate film containing 1% to 0.15% by weight is disclosed.

  However, in the invention described in Patent Document 1, when the amount of fine particles having an average particle size of 0.5 μm or more is increased, the amount of ultraviolet absorber or cellulose triacetate is also increased. In some cases, the particle size in the film becomes large or a spot defect that can be visually confirmed. In particular, in the case of a thin film, since a large amount of an ultraviolet absorber is necessary, it is difficult to control the particle diameter of the aggregate in the case of fine particles formed of secondary particle aggregates, and the above spot defects occur frequently. .

  In addition, in the invention described in Patent Document 1, as a method for adding fine particles to the film, a cellulose acetate dope and an additive solution containing fine particles and an ultraviolet absorber are separately prepared and mixed with a static mixer. Yes.

  In the case of such a method described in Patent Document 1, uniform mixing of a plurality of additives becomes a problem. Particularly when the solubility of the resin is reduced due to a decrease in temperature in winter or the like, fine particles, ultraviolet absorbers, etc. The mixed state of the additive is deteriorated, causing problems such as generation of aggregates that cause spot defects, minute unevenness of the ultraviolet absorber, and variation in the distribution state of the fine particles.

  As a method for producing these cellulose ester films, a solution casting method in which the above resin is dissolved in a solvent and cast on a metal support or the like is used, and the solvent is, for example, methylene chloride. Chlorine organic solvents are preferably used because of their good solubility in the resin and the advantage of easy drying due to their low boiling point in the drying step.

  However, since methylene chloride is highly volatile, it cannot be completely prevented from leaking into the atmosphere, and an improvement in environmental safety is desired. In order to improve this, there have been attempts to increase the concentration of the solution to reduce the amount used, to promote the sealing of the drying process, and to improve the solvent recovery rate, but this has not been fully solved. was there. In recent years, the use of chlorinated hydrocarbon solvents such as methylene chloride has been restricted from the viewpoint of protecting the global environment, and there is a desire to avoid the use of chlorinated hydrocarbon solvents such as methylene chloride. Is growing.

  The object of the present invention is to solve the above-mentioned problems of the prior art, and with the diversification of liquid crystal display devices, particularly with the rapid spread and enlargement of liquid crystal televisions, various additives in resin films used. Maintain uniformity, reduce optical characteristics and slip in the surface of the film, eliminate spot defects that can become image defects, and consider environmental safety when manufacturing these films, Providing a cellulose ester film that maintains desired optical properties and slipperiness between films even when a non-chlorine organic solvent is used and does not cause image defects, and further provides a method for producing the cellulose ester film, and An object of the present invention is to provide a polarizing plate using a film and a liquid crystal display device using the polarizing plate.

In order to achieve the above object, according to the first aspect of the present invention, the fine particles as a matting agent are dispersed in a solvent in advance and mixed with a cellulose ester solution, and then the mixed solution is cast on a support. The cellulose ester film obtained by the solution casting film forming method in which the web is peeled off from the support after the initial drying on the support and post-drying is performed, and the average particle diameter of the granular material in the cellulose ester film Is b, and the average primary particle diameter of the fine particles is c,
6 ≦ b / c ≦ 90
It is characterized by satisfying the relational expression of

Next, the invention according to claim 2 of the present invention is the cellulose ester film according to claim 1, wherein the average particle diameter of the granular material in the fine particle dispersion is a, and the average of the granular material in the cellulose ester film. When the particle diameter is b,
2 ≦ b / a ≦ 8
It is characterized by satisfying the relational expression of

  The invention according to claim 3 of the present invention is the cellulose ester film according to claim 1 or 2, wherein the solvent used for dispersing the fine particles is a non-chlorine organic solvent.

  Invention of Claim 4 of this invention is a cellulose-ester film as described in any one of the said Claims 1-3, Comprising: The solvent which melt | dissolves a cellulose ester is a non-chlorine type organic solvent as the characteristics. Yes.

Invention of Claim 5 of this invention is a cellulose-ester film as described in any one of the said Claims 1-4, Comprising: The cellulose-ester solution melt | dissolved with the solvent is 0.1 to 1.0 weight% The molecular weight of the aggregate obtained by diluting to 50,000 and measuring by the static light scattering method is 50,000 to 1,000,000, the square of inertia is 20 to 100 nm, and the second virial coefficient is 2.0 × 10 ^{−4 to} 2.0 × 10 ^−. It is characterized by ³ .

  According to the sixth aspect of the present invention, the ultraviolet absorber is previously dissolved in a solvent and mixed with the cellulose ester solution, and then the mixed solution is cast on the support, and after the initial drying on the support, the support is performed. A cellulose ester film obtained by a solution casting film forming method in which a web is peeled off from a body and post-drying is performed, and the concentration of the ultraviolet absorbent in the ultraviolet absorbent solution is 3 to 20% by weight. It is a feature.

  Next, the invention according to claim 7 of the present invention is the cellulose ester film according to claim 6, characterized in that 2 to 10% by weight of the cellulose ester resin is contained in the ultraviolet absorbent solution. Yes.

  The invention according to claim 8 of the present invention is the cellulose ester film according to claim 6 or 7, wherein the solvent used in the ultraviolet absorbent solution is a non-chlorine organic solvent.

  Invention of Claim 9 of this invention is a cellulose-ester film as described in any one of the said Claims 5-8, Comprising: Ultraviolet absorber by adding an ultraviolet absorber solution in-line to a cellulose-ester solution. It is characterized by containing.

  According to the tenth aspect of the present invention, the fine particles as the matting agent are previously dispersed in a solvent, and the ultraviolet absorbent is previously dissolved in the solvent, and the fine particle dispersion and the ultraviolet absorbent solution are mixed with the cellulose ester solution. After that, the mixed solution was cast on a support, and after the initial drying on the support, the web was peeled off from the support, and the cellulose ester film obtained by a solution casting film forming method in which post-drying was performed. In addition, the dispersion of fine particles, the dissolution of the ultraviolet absorber, and the solvent used in the cellulose ester solution are all non-chlorine organic solvents.

According to an eleventh aspect of the present invention, fine particles as a matting agent are dispersed in a solvent in advance, and the fine particle dispersion is mixed with a cellulose ester solution, and then the mixed solution is cast on the support. After the initial drying, the cellulose ester film is produced by a solution casting film forming method in which the web is peeled off from the support and post-drying is performed, wherein the average particle diameter in the cellulose ester film is b, and the average primary particle size When the particle diameter is c,
6 ≦ b / c ≦ 90
It is characterized by satisfying the relational expression of

According to a twelfth aspect of the present invention, in the method according to the eleventh aspect, the fine particles as the matting agent are previously dispersed in a solvent, the fine particle dispersion is mixed with the cellulose ester solution, and then the mixed solution is placed on the support. The cellulose ester film is produced by a solution casting film forming method in which the web is peeled off from the support after the initial drying on the support and post-drying is performed. When the average particle diameter of the product is a and the average particle diameter of the granular material in the cellulose ester film is b,
2 ≦ b / a ≦ 8
It is characterized by satisfying the relational expression of

  A thirteenth aspect of the present invention is the method for producing a cellulose ester film according to the eleventh or twelfth aspect, wherein the solvent used for dispersing the fine particles is a non-chlorine organic solvent.

  Invention of Claim 14 of this invention is a manufacturing method of the cellulose ester as described in any one of the said Claims 11-13, Comprising: The solvent which melt | dissolves a cellulose ester is a non-chlorine type organic solvent. It is characterized by that.

  In the invention according to claim 15 of the present invention, an ultraviolet absorber is dissolved in a solvent in advance, and the ultraviolet absorber solution is mixed with a cellulose ester solution, and then the mixed solution is cast on the support. After the initial drying, a cellulose ester film is produced by a solution casting film forming method in which the web is peeled off from the support and post-drying is performed, and the ultraviolet absorbent concentration in the ultraviolet absorbent solution is 3-20. It is characterized by weight percent.

  Next, the invention according to claim 16 of the present invention is the method for producing a cellulose ester film according to claim 15, wherein the cellulose ester resin is contained in the ultraviolet absorbent solution in an amount of 2 to 10% by weight. It is characterized by.

  The invention according to claim 17 of the present invention is the cellulose ester production method according to claim 15 or 16, characterized in that the solvent used in the ultraviolet absorbent solution is a non-chlorine organic solvent.

  Invention of Claim 18 of this invention is a manufacturing method of the cellulose-ester film as described in any one of the said Claims 15-17, Comprising: By adding an ultraviolet absorber solution to a cellulose-ester solution in-line. It is characterized by containing an ultraviolet absorber.

  According to the nineteenth aspect of the present invention, the fine particles as the matting agent are dispersed in a solvent in advance, and the ultraviolet absorbent is dissolved in the solvent in advance, and the fine particle dispersion and the ultraviolet absorbent solution are mixed with the cellulose ester solution. Then, the mixed solution is cast on a support, and after initial drying on the support, the web is peeled off from the support, and a cellulose ester film is produced by a solution casting film forming method in which post-drying is performed. And it is manufactured using the dope whose content of the chlorine-type organic solvent contained in the dope to cast is 1 weight% or less.

  The invention of a polarizing plate according to claim 20 of the present invention is characterized in that the cellulose ester film according to any one of claims 1 to 11 is bonded to at least one surface of a polarizing film. .

  The invention of a liquid crystal display device according to claim 21 of the present invention is characterized by using the polarizing plate according to claim 20.

According to the first aspect of the present invention, as described above, after the fine particles as the matting agent are dispersed in a solvent in advance and mixed with the cellulose ester solution, the mixed solution is cast on the support, A cellulose ester film obtained by a solution casting film forming method in which the web is peeled off from the support and subjected to post-drying after the initial drying, wherein the average particle diameter of the granular material in the cellulose ester film is b, fine particles When the average primary particle diameter of c is c,
6 ≦ b / c ≦ 90
According to the cellulose ester film of the present invention, it is possible to reduce the “variation” in the film plane of optical properties and slipperiness, and consequently the cellulose of the present invention. There is an effect that it is possible to eliminate a spot defect that can be an image defect of a liquid crystal display device including a polarizing plate using an ester film.

Next, the invention according to claim 2 of the present invention is the cellulose ester film according to claim 1, wherein the average particle diameter of the granular material in the fine particle dispersion is a, and the average of the granular material in the cellulose ester film. When the particle diameter is b,
2 ≦ b / a ≦ 8
According to the cellulose ester film of the present invention, it is possible to further reduce the “variation” in the film plane of optical properties and slipperiness, and this The spot defect which can become an image defect of the liquid crystal display device which comprises the polarizing plate using the cellulose ester film of the invention can be eliminated.

  In the cellulose ester film according to claim 1 or 2 of the present invention, the solvent used for dispersion of the fine particles is a non-chlorine organic solvent, and the solvent for dissolving the cellulose ester is a non-chlorine organic solvent. preferable. Thus, in consideration of environmental safety when producing a cellulose ester film, even if a non-chlorine organic solvent is used, the cellulose ester film maintains desired optical properties and slipperiness between the films, and thus the present invention. This produces an effect that it is possible to eliminate a spot defect that can be an image defect of a liquid crystal display device including a polarizing plate using the cellulose ester film.

Invention of Claim 5 of this invention is obtained by diluting the cellulose-ester solution melt | dissolved with the solvent to 0.1-1.0 weight% in said cellulose-ester film, and measuring by a static light scattering method. The aggregate molecular weight is 50,000 to 1,000,000, the inertial square radius is 20 to 100 nm, and the second virial coefficient is 2.0 × 10 ^{−4 to} 2.0 × 10 ^−3. For example, the cellulose ester solution having an aggregate molecular weight, inertial square radius, and second virial coefficient in the above ranges shows that the resin is uniformly dissolved in the solvent, and the dissolved state is good. The formed cellulose ester film can also prevent the occurrence of spot defects caused by poor resin dissolution.

  According to the sixth aspect of the present invention, the ultraviolet absorber is previously dissolved in a solvent and mixed with the cellulose ester solution, and then the mixed solution is cast on the support, and after the initial drying on the support, the support is performed. A cellulose ester film obtained by a solution casting film forming method in which a web is peeled off from a body and post-drying is performed, and the concentration of the ultraviolet absorbent in the ultraviolet absorbent solution is 3 to 20% by weight. According to the cellulose ester film of the present invention, the uniformity of the ultraviolet absorber contained in the polarizing plate protective film in order to prevent the deterioration of the polarizer is maintained in the film plane, and the optical characteristics in the film plane are maintained. In addition, it is possible to reduce the “dispersion” of the liquid crystal and to eliminate spot defects that can be image defects, and thus to include a polarizing plate using the cellulose ester film of the present invention. An effect that it is possible to eliminate the spot defects which can be a image defect crystal display device.

  Next, the invention according to claim 7 of the present invention is the cellulose ester film according to claim 6, characterized in that 2 to 10% by weight of the cellulose ester resin is contained in the ultraviolet absorbent solution. Therefore, according to the cellulose ester film of the present invention, by incorporating the cellulose ester resin in the above range in the ultraviolet absorbent solution, it becomes possible to uniformly mix the ultraviolet absorbent into the main resin. Thus, it is possible to suppress variations in ultraviolet transmittance in the in-plane direction of the film while having a desired ultraviolet absorbing ability.

  The invention according to claim 8 of the present invention is the cellulose ester film according to claim 6 or 7, wherein the solvent used for the ultraviolet absorbent solution is a non-chlorine organic solvent. Thus, in consideration of environmental safety when producing a cellulose ester film, even if a non-chlorine organic solvent is used, the cellulose ester film maintains desired optical properties and slipperiness between the films, and thus the present invention. This produces an effect that it is possible to eliminate a spot defect that can be an image defect of a liquid crystal display device including a polarizing plate using the cellulose ester film.

  Invention of Claim 9 of this invention is a cellulose-ester film as described in any one of the said Claims 5-8, Comprising: Ultraviolet absorber by adding an ultraviolet absorber solution in-line to a cellulose-ester solution. According to the cellulose ester film of the present invention, when the ultraviolet absorbing ability of the film is out of the desired range by adding the ultraviolet absorbent solution in-line to the cellulose ester solution. It is possible to adjust by changing the in-line addition flow rate of the ultraviolet absorbent solution, and it is possible to suppress variation in the amount of absorbed ultraviolet light for each film roll.

  The invention described in claim 10 of the present invention is characterized in that the solvent used in the dispersion of fine particles, the dissolution of the ultraviolet absorber, and the cellulose ester solution are all non-chlorine organic solvents. According to the cellulose ester film, considering the environmental safety when producing the cellulose ester film, even if a non-chlorine organic solvent is used, the cellulose ester film maintains the desired optical properties and the slipperiness between the films, As a result, the effect that the spot defect which may become an image defect of the liquid crystal display device which comprises the polarizing plate using the cellulose-ester film of this invention can be eliminated is produced.

According to an eleventh aspect of the present invention, fine particles as a matting agent are dispersed in a solvent in advance, and the fine particle dispersion is mixed with a cellulose ester solution, and then the mixed solution is cast on the support. After the initial drying, the cellulose ester film is produced by a solution casting film forming method in which the web is peeled off from the support and post-drying is performed, wherein the average particle diameter in the cellulose ester film is b, and the average primary particle size When the particle diameter is c,
6 ≦ b / c ≦ 90
According to the method for producing a cellulose ester film of the present invention, the uniformity of various additives can be maintained in the film, whereby the optical properties of the cellulose ester film can be maintained. It is possible to reduce the “variation” in the film plane of characteristics and slipperiness. In addition, in consideration of environmental safety when producing a cellulose ester film, even if a non-chlorine organic solvent is used, the cellulose ester film maintains desired optical properties and slipperiness between films, and image defects do not occur. There is an effect.

According to a twelfth aspect of the present invention, in the method according to the eleventh aspect, the fine particles as the matting agent are previously dispersed in a solvent, the fine particle dispersion is mixed with the cellulose ester solution, and then the mixed solution is placed on the support. The cellulose ester film is produced by a solution casting film forming method in which the web is peeled off from the support after the initial drying on the support and post-drying is performed. When the average particle diameter of the product is a and the average particle diameter of the granular material in the cellulose ester film is b,
2 ≦ b / a ≦ 8
According to the cellulose ester film of the present invention, it is possible to further reduce the “variation” in the film plane of optical properties and slipperiness, and this The spot defect which can become an image defect of the liquid crystal display device which comprises the polarizing plate using the cellulose ester film of the invention can be eliminated.

  In the method for producing a cellulose ester film according to claim 11 or 12 of the present invention, the solvent used for dispersing fine particles is a non-chlorine organic solvent, and the solvent for dissolving the cellulose ester is a non-chlorine organic solvent. Is preferred. Thus, in consideration of environmental safety when producing a cellulose ester film, even if a non-chlorine organic solvent is used, the cellulose ester film maintains desired optical properties and slipperiness between the films, and thus the present invention. This produces an effect that it is possible to eliminate a spot defect that can be an image defect of a liquid crystal display device including a polarizing plate using the cellulose ester film.

  In the invention according to claim 15 of the present invention, an ultraviolet absorber is dissolved in a solvent in advance, and the ultraviolet absorber solution is mixed with a cellulose ester solution, and then the mixed solution is cast on the support. After the initial drying, a cellulose ester film is produced by a solution casting film forming method in which the web is peeled off from the support and post-drying is performed, and the ultraviolet absorbent concentration in the ultraviolet absorbent solution is 3-20. According to the method for producing a cellulose ester film of the present invention, the uniformity of the ultraviolet absorber contained in the polarizing plate protective film in order to prevent the deterioration of the polarizer is obtained. It is possible to reduce the “variation” of the optical characteristics within the film surface, and to eliminate the spot defects that can become image defects, and thus to be manufactured by the method of the present invention. And there is an effect that the cellulose ester film can be eliminated spot defects which can be a image defect of the liquid crystal display device having a polarizing plate was used.

  Next, the invention according to claim 16 of the present invention is the method for producing a cellulose ester film according to claim 15, wherein the cellulose ester resin is contained in the ultraviolet absorbent solution in an amount of 2 to 10% by weight. According to the method for producing a cellulose ester film of the present invention, by adding the cellulose ester resin in the above range in the ultraviolet absorbent solution, the ultraviolet absorbent is added to the main resin. Can be uniformly mixed, and variation in ultraviolet transmittance in the in-plane direction of the film can be suppressed while having a desired ultraviolet absorbing ability.

  The invention according to claim 17 of the present invention is the method for producing a cellulose ester according to claim 15 or 16, wherein the solvent used in the ultraviolet absorbent solution is a non-chlorine organic solvent. Thus, in consideration of environmental safety when producing a cellulose ester film, even if a non-chlorine organic solvent is used, the cellulose ester film maintains desired optical properties and slipperiness between the films, and thus the present invention. This produces an effect that it is possible to eliminate a spot defect that can be an image defect of a liquid crystal display device including a polarizing plate using the cellulose ester film.

  Invention of Claim 18 of this invention is a manufacturing method of the cellulose-ester film as described in any one of the said Claims 15-17, Comprising: By adding an ultraviolet absorber solution to a cellulose-ester solution in-line. According to the method for producing a cellulose ester film of the present invention, the ultraviolet absorbing ability of the film is desired by adding the ultraviolet absorbent solution in-line to the cellulose ester solution. When it is out of the range, it is possible to adjust by changing the in-line addition flow rate of the ultraviolet absorbent solution, and it is possible to suppress the variation in the amount of absorbed ultraviolet rays for each film roll.

  According to the nineteenth aspect of the present invention, the fine particles as the matting agent are dispersed in a solvent in advance, and the ultraviolet absorbent is dissolved in the solvent in advance, and the fine particle dispersion and the ultraviolet absorbent solution are mixed with the cellulose ester solution. Then, the mixed solution is cast on a support, and after initial drying on the support, the web is peeled off from the support, and a cellulose ester film is produced by a solution casting film forming method in which post-drying is performed. The method for producing a cellulose ester film according to the present invention is characterized in that it is produced using a dope having a chlorinated organic solvent content of 1% by weight or less contained in the dope to be cast. According to the present invention, a non-chlorine organic solvent is used in consideration of environmental safety when producing a cellulose ester film. In this case, the chlorine-based organic solvent is added in an amount of 1% by weight or more in the dope. The obtained cellulose ester film maintains desired optical properties and slipperiness between the films, and thus has a polarizing plate using the cellulose ester film of the present invention. It is possible to eliminate spot defects that can be image defects.

  The invention of a polarizing plate according to claim 20 of the present invention is characterized in that the cellulose ester film according to any one of claims 1 to 11 is bonded to at least one surface of a polarizing film. Therefore, according to the polarizing plate of the present invention, since the cellulose ester film having a small “variation” in the film surface of optical properties and slipperiness is used, it is possible to eliminate spot defects that can be image defects. There is an effect.

  The invention of a liquid crystal display device according to claim 21 of the present invention is characterized by using the polarizing plate according to claim 20, and according to the liquid crystal display device of the present invention, a spot that can be an image defect. Because it uses a polarizing plate with excellent quality without defects and bright spot foreign matter, it has excellent performance, and for the rapid spread of LCD TVs and the increase in screen size due to the diversification of liquid crystal display devices, There is an effect that it is possible to respond sufficiently.

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

  First, the cellulose ester film of the present invention is prepared by dispersing fine particles as a matting agent in a solvent in advance and mixing with a cellulose ester solution, then casting the mixed solution on a support, and after initial drying on the support, It is a cellulose ester film obtained by a solution casting film forming method in which a web is peeled from a support and post-drying is performed.

In the cellulose ester film according to the present invention, when the average particle diameter of the granular material in the cellulose ester film is b and the average primary particle diameter of the fine particles is c,
6 ≦ b / c ≦ 90
It is characterized by satisfying the relational expression of

  Here, if b / c is less than 6, the degree of growth of the particles in the film is small with respect to the primary particle diameter, so that the slipperiness of the film, which is the original purpose of the fine particles, deteriorates, and the films are separated from each other. Not only does it become sticky and handling deteriorates, but the film is wrinkled during the film winding process, which leads to deformation of the film. On the other hand, if b / c exceeds 90, the degree of growth of the particles in the film is remarkably increased with respect to the primary particle size, so that the transparency of the film is deteriorated or the particles themselves are likely to be spot defects.

Further, the cellulose ester film according to the present invention, when the average particle diameter of the granular material in the fine particle dispersion is a, and the average particle diameter of the granular material in the cellulose ester film is b,
2 ≦ b / a ≦ 8
It is characterized by satisfying the relational expression of

  Here, if b / a is less than 2, the degree of growth of the particles in the film is small with respect to the dispersed particle size, so that the slipperiness of the film, which is the original purpose of the fine particles, deteriorates, Not only does it become sticky and handling deteriorates, but the film is wrinkled during the film winding process, which leads to deformation of the film. On the other hand, when b / a exceeds 8, the degree of growth of the particles in the film is remarkably increased with respect to the dispersed particle diameter, so that the transparency of the film is deteriorated or the particles themselves are likely to be spot defects.

  In the present invention, the solvent used for dispersing the fine particles may be a non-chlorine organic solvent. The solvent for dissolving the cellulose ester may also be a non-chlorine organic solvent.

The cellulose ester film according to the present invention has an associated molecular weight of 50,000 to 1,000,000 obtained by diluting a cellulose ester solution dissolved in a solvent to 0.1 to 1.0% by weight and measuring by a static light scattering method. The radius is 20 to 100 nm, and the second virial coefficient is 2.0 × 10 ^{−4 to} 2.0 × 10 ⁻³ .

Here, if the molecular weight of the aggregate obtained by measurement by the static light scattering method is less than 50000, the strength of the resin at the time of film formation decreases, and deformation occurs when bonded to the polarizing plate. Since it becomes easy, it is not preferable. Moreover, since the viscosity of a solution will become high too much when an aggregate molecular weight exceeds 1000000, handling in a process becomes difficult. In addition, if the inertial square radius is less than 20 nm, it means that the molecular spread in the solution is small, and the network between the resins is weak. This is not preferable because a peeling residue may occur or the film may be cut off without being peeled off. On the other hand, if the inertial square radius exceeds 100 nm, it means that the resin is not sufficiently dissolved in the solution, and spot defects and the like occur in the film and cannot be used as a film for a liquid crystal display device. Furthermore, if the second virial coefficient is less than 2.0 × 10 ⁻⁴ , it means that the resin does not sufficiently dissolve in the solution, and spot defects and the like occur in the film, and for liquid crystal display devices It cannot be used as a film. Moreover, when the second virial coefficient exceeds 2.0 × 10 ⁻³ , it means that the dissolution of the resin in the solution has progressed too much, and since the network between the resins is weak, when peeling from the metal support For example, a peeling residue may be generated on the support or may be cut off without being peeled off.

  In the present invention, after the ultraviolet absorber is dissolved in a solvent in advance and mixed with the cellulose ester solution, the mixed solution is cast on the support, and after the initial drying on the support, the web is peeled off from the support. A cellulose ester film obtained by a solution casting film forming method in which post-drying is performed, wherein the concentration of the ultraviolet absorbent in the ultraviolet absorbent solution is 3 to 20% by weight.

  Here, if the concentration of the UV absorber in the UV absorber solution is less than 3% by weight, a large amount of the UV absorber solution must be added to the resin in order to maintain the desired UV absorbing ability. Mixing becomes difficult, and the variation in the amount of UV absorption in the film after film formation becomes large. If the concentration of the UV absorber in the UV absorber solution exceeds 20% by weight, the UV absorber will not be sufficiently dissolved in the UV absorber solution, resulting in increased spot defects in the film after film formation. Or the variation in the amount of UV absorption in the surface becomes large, which is not preferable.

  Moreover, it is preferable that cellulose ester resin contains 2-10 weight% in a ultraviolet absorber solution. Here, if the cellulose ester resin in the ultraviolet absorbent solution is less than 2% by weight, the viscosity is low, so it does not mix well when mixing with the main cellulose ester resin solution. Variation in UV absorption increases. When the cellulose ester resin in the ultraviolet absorbent solution exceeds 10% by weight, the viscosity increase due to the resin is large, and this also makes it impossible to mix the ultraviolet absorbent well.

  Here, the solvent used for the ultraviolet absorbent solution may be a non-chlorine organic solvent.

  In this invention, it is preferable to contain a ultraviolet absorber by adding an ultraviolet absorber solution in-line to a cellulose-ester solution.

  In the present invention, the fine particles as a matting agent are dispersed in a solvent in advance, the ultraviolet absorber is dissolved in a solvent in advance, the fine particle dispersion and the ultraviolet absorbent solution are mixed with the cellulose ester solution, and then the mixed solution is prepared. A cellulose ester film obtained by a solution casting film-forming method in which a web is cast on a support, and after the initial drying on the support, the web is peeled off from the support and post-drying is performed. It is preferable that the solvent used for the dissolution of the ultraviolet absorber and the cellulose ester solution is a non-chlorine organic solvent.

  In the method for producing a cellulose ester film according to the present invention, fine particles as a matting agent are dispersed in a solvent in advance, the fine particle dispersion is mixed with a cellulose ester solution, and then the mixed solution is cast onto a support. After the initial drying, the cellulose ester film is produced by a solution casting film forming method in which the web is peeled off from the support and post-drying is performed.

In the method for producing a cellulose ester film of the present invention, when the average particle diameter in the cellulose ester film is b and the average primary particle diameter of the fine particles is c,
6 ≦ b / c ≦ 90
It is characterized by satisfying the relational expression of

  Here, if b / c is less than 6, the degree of growth of the particles in the film is small with respect to the primary particle diameter, so that the slipperiness of the film, which is the original purpose of the fine particles, deteriorates, and the films are separated from each other. Not only does it become sticky and handling deteriorates, but the film is wrinkled during the film winding process, which leads to deformation of the film. On the other hand, if b / c exceeds 90, the degree of growth of the particles in the film is remarkably increased with respect to the primary particle size, so that the transparency of the film is deteriorated or the particles themselves are likely to be spot defects.

Furthermore, in the method for producing a cellulose ester film according to the present invention, fine particles as a matting agent are dispersed in a solvent in advance, the fine particle dispersion is mixed with a cellulose ester solution, and then the mixed solution is cast onto a support. A method for producing a cellulose ester film by a solution casting film forming method in which a web is peeled off from a support after the initial drying and subjected to post-drying, wherein the average particle diameter of the granular material in the fine particle dispersion is a When the average particle diameter of the granular material in the cellulose ester film is b,
2 ≦ b / a ≦ 8
It is characterized by satisfying the relational expression of

  Here, if b / a is less than 2, the degree of growth of the particles in the film is small with respect to the dispersed particle size, so that the slipperiness of the film, which is the original purpose of the fine particles, deteriorates, Not only does it become sticky and handling deteriorates, but the film is wrinkled during the film winding process, which leads to deformation of the film. On the other hand, when b / a exceeds 8, the degree of growth of the particles in the film is remarkably increased with respect to the dispersed particle diameter, so that the transparency of the film is deteriorated or the particles themselves are likely to be spot defects.

  Here, the solvent used for dispersion of the fine particles may be a non-chlorine organic solvent. The solvent for dissolving the cellulose ester may also be a non-chlorine organic solvent.

  Further, the method for producing a cellulose ester film according to the present invention comprises dissolving an ultraviolet absorber in a solvent in advance, mixing the ultraviolet absorber solution with the cellulose ester solution, and then casting the mixed solution on the support. A method for producing a cellulose ester film by a solution casting film forming method in which the web is peeled off from the support after the initial drying and the post-drying is performed, and the concentration of the ultraviolet absorbent in the ultraviolet absorbent solution is 3 It is characterized by ˜20% by weight.

  Here, if the concentration of the UV absorber in the UV absorber solution is less than 3% by weight, a large amount of the UV absorber solution must be added to the resin in order to maintain the desired UV absorbing ability. Mixing becomes difficult, and the variation in the amount of UV absorption in the film after film formation becomes large. If the concentration of the UV absorber in the UV absorber solution exceeds 20% by weight, the UV absorber will not be sufficiently dissolved in the UV absorber solution, resulting in increased spot defects in the film after film formation. Or the variation in the amount of UV absorption in the surface becomes large, which is not preferable.

  Moreover, it is preferable that cellulose ester resin contains 2-10 weight% in a ultraviolet absorber solution. Here, if the cellulose ester resin in the ultraviolet absorbent solution is less than 2% by weight, the viscosity is low, so it does not mix well when mixing with the main cellulose ester resin solution. Variation in UV absorption increases. When the cellulose ester resin in the ultraviolet absorbent solution exceeds 10% by weight, the viscosity increase due to the resin is large, and this also makes it impossible to mix the ultraviolet absorbent well.

  In the method for producing a cellulose ester of the present invention, the solvent used in the ultraviolet absorbent solution may be a non-chlorine organic solvent.

  In the manufacturing method of the cellulose ester of this invention, it is preferable to contain a ultraviolet absorber by adding an ultraviolet absorber solution in-line to a cellulose ester solution.

  In addition, the cellulose ester production method of the present invention is prepared by dispersing fine particles as a matting agent in a solvent in advance and dissolving an ultraviolet absorber in a solvent in advance, and the fine particle dispersion and the ultraviolet absorber solution are mixed with a cellulose ester solution. After mixing, the mixed solution is cast on a support, and after initial drying on the support, the web is peeled off from the support and a cellulose ester film is produced by a solution casting film forming method in which post-drying is performed. And it is manufactured using the dope whose content of the chlorine-type organic solvent contained in the dope to cast is 1 weight% or less.

  Here, when the content of the chlorinated organic solvent contained in the dope to be cast exceeds 1% by weight, not only the possibility of leakage to the outside in the production process from the aspect of environmental safety is increased, Chlorinated organic solvents may remain in the product after film formation, which is not preferable.

  The polarizing plate according to the present invention is characterized in that the above cellulose ester film is bonded to at least one surface of a polarizing film.

  A liquid crystal display device according to the present invention is characterized by using the polarizing plate.

  Next, the present invention will be specifically described.

  First, in the present invention, examples of the cellulose ester include cellulose triacetate, cellulose diacetate, cellulose acetate butyrate, and cellulose acetate propionate. In the case of cellulose triacetate, cellulose triacetate having a degree of polymerization of 250 to 400 and a bound acetic acid amount of 54 to 62.5% is preferable, and a cellulose triacetate having a bound acetic acid amount of 58 to 62.5% increases the base strength. preferable. As the cellulose triacetate, either cellulose triacetate synthesized from cotton linter or cellulose triacetate synthesized from wood pulp can be used alone or in combination.

  It is preferable to use a large amount of cellulose triacetate synthesized from a cotton linter that has good releasability from a belt or drum because productivity efficiency is increased. The ratio of cellulose triacetate synthesized from cotton linter is preferably 60% by weight or more, since the effect of peelability becomes remarkable. More preferably, it is 85% by weight or more, and most preferably used alone.

  Although it does not specifically limit as a plasticizer for cellulose esters that can be used in the present invention, in the phosphate ester type, triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, diphenyl biphenyl phosphate, trioctyl phosphate , Tributyl phosphate, etc. for phthalate esters, such as diethyl phthalate, dimethoxyethyl phthalate, dimethyl phthalate, dioctyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate, etc. Rate, ethyl phthalyl ethyl glycolate, methyl phthalyl ethyl glycolate, butyl phthalyl butyl glycolate, etc. Or used in Germany, or preferably used in combination.

  If necessary, two or more plasticizers may be used in combination. In this case, the proportion of phosphate ester plasticizer used is 50% or less, which hardly causes hydrolysis of the cellulose ester film and is durable. It is preferable because of its excellent properties.

  It is more preferable that the ratio of the phosphate ester plasticizer is small, and it is particularly preferable to use only a phthalate ester or glycolate ester plasticizer.

  Furthermore, in order to bring the water absorption rate and the water content within a specific range, the amount of the plasticizer is preferably 3 to 30% by weight, more preferably 10 to 25% by weight, based on the cellulose ester. More preferably, it is 15 to 25% by weight. If it exceeds 30% by weight, the mechanical strength and dimensional stability are deteriorated, which is not preferable.

  In the present invention, an ultraviolet absorber is used for the cellulose ester film. As an ultraviolet absorber, it absorbs ultraviolet light having a wavelength of 380 nm or less from the viewpoint of preventing deterioration of the liquid crystal or polarizer, and absorbs visible light having a wavelength of 400 nm or more as little as possible from the viewpoint of good liquid crystal display properties. Those are preferably used. In particular, the transmittance at a wavelength of 380 nm needs to be 10% or less, preferably 5% or less, more preferably 2% or less.

  Examples of commonly used compounds include, but are not limited to, oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, triazine compounds, cyanoacrylate compounds, nickel complex compounds, and the like.

  In this invention, it is preferable to use 1 or more types of these ultraviolet absorbers, and you may contain 2 or more types of different ultraviolet absorbers.

  The ultraviolet absorber preferably used in the present invention is a benzotriazole ultraviolet absorber, a benzophenone ultraviolet absorber, or the like. An embodiment in which a benzotriazole-based ultraviolet absorber with less unnecessary coloring is added to the cellulose ester film is particularly preferable.

  In the present invention, the ultraviolet absorber is added to the dope after the ultraviolet absorber is dissolved in a non-chlorine organic solvent alone or in advance with other additives or cellulose ester resin. For an inorganic powder that does not dissolve in an organic solvent, a dissolver or a sand mill is used in the organic solvent and cellulose ester to disperse and then added to the dope.

  The amount of the ultraviolet absorber used in the present invention is 0.1 to 2.5% by weight, preferably 0.5 to 2.0% by weight, more preferably 0.8 to 2.0% by weight based on the cellulose ester. % By weight. When the amount of the ultraviolet absorber used is more than 2.5% by weight, the transparency tends to deteriorate, which is not preferable.

  In the present invention, examples of the solvent for cellulose ester include acetone, methyl acetate, cyclohexanone, ethyl formate, 1,3-dioxolane, 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-propanol, 1,1,1,3,3,3-hexa Examples include fluoro-2-propanol, 2,2,3,3,3-pentafluoro-1-propanol, and methyl acetoacetate. These solvents may be used alone or in combination of two or more. In particular, methyl acetate and acetone have good solubility in non-chlorinated solvents and can provide a film with excellent transparency.

  In the present invention, the cellulose ester solution contains a lower alcohol having 1 to 6 carbon atoms for the purpose of improving solubility, adjusting viscosity, adjusting drying speed, and promoting gelation when the solution is granulated. Also good. Examples of these lower alcohols include methanol, ethanol, propanol, isopropanol, n-butanol, s-butanol, t-butanol, and cyclohexanol. Of these, methanol, ethanol, and n-butanol are preferable. These lower alcohols are preferably contained in an amount of 2% by weight to 30% by weight based on the total organic solvent. The cellulose ester solution containing a lower alcohol having 1 to 6 carbon atoms can be easily peeled off from a belt or drum which is a support used for casting.

  Hereafter, the manufacturing method of the cellulose ester film by this invention is demonstrated concretely.

  In the method for producing a cellulose ester film according to the present invention, fine particles as a matting agent are preliminarily dispersed in a solvent, the fine particle dispersion is mixed with a cellulose ester solution, and then the mixed solution is cast on a support. After the initial drying, a cellulose ester film is produced by a solution casting film forming method in which the web is peeled from the support and post-drying is performed.

  Here, the manufacturing method of the cellulose ester film by the solution casting film forming method is not particularly limited, and may be a method generally used in the art. For example, U.S. Pat. Nos. 2,492,978, 2,739,070, 2,739,069, 2,492,977, 2,336,310 No. 2,367,603, No. 2,607,704, British Patent No. 64,071, No. 735,892, No. 45-9074, No. 49- Reference can be made to methods described in Japanese Patent Nos. 4554, 49-5614, 60-27562, 61-39890, 62-4208, and the like.

  In the method of the present invention, the type of the pressurized container is not particularly limited as long as it can withstand a predetermined pressure and can be heated and stirred under pressure. In addition to the pressure vessel, other instruments such as a pressure gauge and a thermometer are appropriately disposed.

  The pressurization may be performed by a method of injecting an inert gas such as nitrogen gas or by increasing the vapor pressure of the solvent by heating.

  Heating is preferably performed from the outside. For example, a jacket type is preferable because temperature control is easy.

  The heating temperature with the addition of the solvent is preferably a temperature not lower than the boiling point of the solvent used and in a range where the solvent does not boil, and is preferably set in the range of, for example, 60 ° C. or higher and 80 to 110 ° C. The pressure is determined so that the solvent does not boil at the set temperature.

  After dissolution, take it out from the container while cooling, or extract it from the container with a pump and cool it with a heat exchanger, etc., and use it for film formation, but the cooling temperature at this time may be cooled to room temperature, Cooling to a temperature 5 to 10 ° C. lower than the boiling point and casting at that temperature is more preferable because the dope viscosity can be reduced.

  In the present invention, a dope obtained by dissolving cellulose ester is cast on a support (casting process), and then heated to remove a part of the solvent (drying process on the support), and then from the support. It peels and the peeled film is dried (film drying process), and a cellulose-ester film is obtained.

  As the support in the casting process, a support in which a belt-like or drum-like stainless steel is mirror-finished is used. The temperature of the support in the casting process can be cast at a general temperature range of 0 ° C. to a temperature lower than the boiling point of the solvent, but the dope is gelled by casting on a support at 5 to 30 ° C. In order to increase the peeling limit time, casting on a support at 5 to 15 ° C. is more preferable. The peeling limit time is the time during which the cast dope is on the support 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 process on the support, the dope is cast, once gelled, and when the time from casting to peeling is 100%, the dope temperature is set to 40 to 70 ° C. within 30% from casting. Thus, the evaporation of the solvent is promoted, and it can be peeled off from the support as quickly as possible, and the peel strength is further increased. The dope temperature is preferably set to 55 to 70 ° C. within 30%. This temperature is preferably maintained at 20% or more, more preferably 40% or more.

  For drying on the support, it is preferable to peel from the support with a residual solvent amount of 60 to 150% because the peel strength from the support becomes small, and 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 to 20 ° C. is more preferable.

  The amount of residual solvent in the film is represented by the following formula.

Residual solvent amount = residual volatile matter weight / film weight after heat treatment × 100%
The residual volatile matter weight is a value obtained by subtracting the film weight after the heat treatment from the film weight before the heat treatment when the film is heat treated at 115 ° C. for 1 hour.

  In the film drying step, the film from which the web is peeled off from the support 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 or less. It is preferable for obtaining a film having good properties. In the film drying process, generally, a roll suspension system, a pin tenter system, or a clip tenter system is used for drying while transporting the film. 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 particularly preferable to maintain the width where the amount of residual solvent is large immediately after the web is peeled from the support because the effect of improving the dimensional stability is more exhibited.

  In particular, in the drying process after peeling from the support, the film tends to shrink in the width direction by evaporation of the solvent. Here, the higher the temperature, the greater the shrinkage. 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, a method / tenter for drying the entire drying process as shown in Japanese Patent Application Laid-Open No. 62-46625 or a part of the process while holding the width at both ends of the web with a clip in the width direction. The 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 more preferably in the range of 80 to 140 ° C in order to improve 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.

  In the present invention, a winder related to the production of the cellulose ester film may be generally used, such as a constant tension method, a constant torque method, a taper tension method, a program tension control method with a constant internal stress, and the like. It can be wound up by the method.

  In the present invention, the thickness of the cellulose ester film is generally 20 to 200 [mu] m, but is 20 to 65 [mu] m in order to reduce the thickness and weight of the polarizing plate used in the LCD. More preferably, it is 30-60 micrometers, More preferably, it is 35-50 micrometers. If it is thinner than this, the stiffness of the film will be reduced, so troubles due to wrinkles etc. are likely to occur on the polarizing plate making process, and if it is thicker than this, it will contribute to the thinning of the LCD Few.

  In the present invention, fine particles are added as a matting agent to the cellulose ester film.

  The kind of fine particles may be an inorganic compound or an organic compound. Examples of the inorganic compound include fine particles of silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, tin oxide, and the like. In this, it is preferable that it is a compound containing a silicon atom, and especially a silicon dioxide fine particle is preferable. Examples of the silicon dioxide fine particles include AEROSIL-200, 200V, 300, R972, R972V, R974, R202, R812, R805, OX50, and TT600 manufactured by Aerosil Co., Ltd. AEROSIL 200V and R972V are preferable in terms of controlling dispersibility and particle diameter.

  In the present invention, the fine particles are added in an amount of 0.05 to 0.5% by weight based on the film. Preferably, it is 0.10 to 0.35 weight%, More preferably, it is 0.20 to 0.30 weight%.

For the dispersion of the fine particles, a composition in which the fine particles and the solvent are mixed is treated with a high-pressure dispersion device. The high-pressure dispersion apparatus used for dispersion can be a high-pressure dispersion apparatus that creates special conditions such as high shear and high pressure by passing a composition in which fine particles and a solvent are mixed at high speed through a thin 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.

  The above-mentioned high-pressure dispersion devices include ultra-high pressure homogenizers (trade name: Microfluidizer) manufactured by Microfluidics Corporation or Nanomizers manufactured by Nanomizer, and other high pressure dispersions of Manton Gorin type. Examples thereof include a homogenizer manufactured by Izumi Food Machinery.

  The fine particles are dispersed in a solvent containing 25 to 100% by weight of a water-soluble solvent, and then diluted by adding a water-insoluble organic solvent by 0.5 to 1.5 times with respect to the water-soluble solvent. A cellulose ester film obtained by mixing with a dope dissolved in a solvent, casting the mixed solution on a support, and drying to form a film is obtained. As the water-soluble solvent, lower alcohols are mainly used. Preferred examples of lower alcohols include methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol and the like.

  The water-insoluble solvent is not particularly limited, but it is preferable to use a solvent used in film formation of cellulose ester, and those having a solubility in water of 30% by weight or less are used, and examples thereof include methyl acetate and acetone.

  The fine particles are dispersed in the solvent at a concentration of 1 to 30% by weight. Dispersing at a concentration higher than this is not preferable because the viscosity increases rapidly. The concentration of the fine particles in the dispersion is preferably 5 to 25% by weight, more preferably 10 to 20% by weight.

  The haze of a film can be measured according to the standard of ASTM-D1003-52, for example. The haze is preferably 0 to 0.6%, more preferably 0 to 0.4%, and still more preferably 0.1 to 0.2%.

  In the present invention, as a method of adding fine particles and an ultraviolet absorber to a transparent resin film, an additive solution in which fine particles, an ultraviolet absorber and a resin are dissolved in a solvent is prepared in advance, and a solution casting film is formed. Therefore, a method of adding a dope solution containing a resin as a main component is employed. As a method of addition, it may be added directly to a resin melting pot together with a visualizing agent or the like, or may be added in-line immediately before casting.

  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 film to make the ends bulky.

Here, the ratio X of the knurling height (h: μm) to the film thickness (d: μm) is X (%) = (h / d) × 100
In this case, the range of X = 0 to 25% is good for stabilizing the winding property.

  The ratio X is preferably 0 to 15%, more preferably 0 to 10%. From this range, if the knurling height ratio is large, the winding shape is likely to be deformed, and if the ratio is small, the winding property deteriorates, which is not preferable.

  It is preferable that the cellulose ester film has less foreign matter. In particular, it is preferable that there are few foreign substances recognized in the polarization crossed Nicol state.

  The foreign substance recognized in the polarization crossed Nicol state refers to that measured by placing two polarizing plates in a direct (crossed Nicol) state and placing a cellulose ester film between them. In the polarization crossed Nicol state, such a foreign substance is observed by shining only the part of the foreign substance in the dark field, so that the size and number can be easily identified.

In the above, a means for obtaining a cellulose ester film with few foreign substances is not particularly limited, but it can be achieved by filtering a dope composition in which cellulose ester is dissolved in a solvent using the following filter paper. In this case, it is preferable to use a filter paper having a filtering time of 20 sec or more as a kind of filter paper, and form a film by filtering at a filtration pressure of 16 kg / cm ² or less. More preferably, filtering is performed using a filter paper of 30 sec or more and a filtration pressure of 12 kg / cm ² or less, and more preferably using a filter paper of 40 sec or more and a filtration pressure of 10 kg / cm ² or less. Moreover, it is more preferable to use two or more of the above filter papers. The filtration pressure can be controlled by appropriately selecting the filtration flow rate and the filtration area.

  Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited thereto.

Example 1
(Preparation of dope solution A)
100 parts by weight of cellulose acetate propionate (acetyl group substitution degree 1.9, propionyl group substitution degree 0.8)
Triphenyl phosphate 8 parts by weight Ethyl phthalyl ethyl glycolate 2 parts by weight Methyl acetate 245 parts by weight Ethanol 105 parts by weight The above materials are put into a sealed container, heated and stirred to completely dissolve, and the solution is filtered. A dope solution B was prepared by filtration using Azumi Filter Paper Co., Ltd. (Azumi Filter Paper No. 24). Moreover, this dope solution B was filtered with a filter medium (Nippon Seisen Co., Ltd., Finemet NF) in the film production line.

(Fine particle dispersion A)
Aerosil 972V (manufactured by Nippon Aerosil Co., Ltd.) 10 parts by weight (average primary particle diameter 16 nm, apparent specific gravity 90 g / liter)
Ethanol 75 parts by weight The above materials were stirred and mixed with a dissolver for 30 minutes, and then dispersed with Manton Gorin. 75 parts by weight of methyl acetate was added to the silicon oxide dispersion while stirring, and the mixture was stirred and mixed with a dissolver for 30 minutes to prepare a fine particle dispersion diluent A.

(Preparation of inline additive solution A)
Methyl acetate 100 parts by weight Tinuvin 109 (manufactured by Ciba Specialty Chemicals) 4 parts by weight Tinuvin 171 (manufactured by Ciba Specialty Chemicals) 4 parts by weight Tinuvin 326 (manufactured by Ciba Specialty Chemicals) 2 parts by weight The solution was completely dissolved and filtered with stirring and heating.

  To this, 20 parts by weight of the fine particle dispersion diluent A was added with stirring, and further stirred for 30 minutes, and then 5 parts by weight of cellulose acetate propionate (acetyl group substitution degree 1.9, propionyl group substitution degree 0.8). Was added with stirring, and the mixture was further stirred for 60 minutes, and then filtered through a polypropylene wind cartridge filter (manufactured by Advantech Toyo Co., Ltd., product number TCW-PPS-1N) to prepare an in-line additive solution A.

  In the in-line additive liquid line, the in-line additive liquid A was filtered with a filter medium (trade name Finemet NF, manufactured by Nippon Seisen Co., Ltd.). Add 4 parts by weight of the filtered in-line additive A to 100 parts by weight of the filtered dope liquid A, and mix thoroughly with an in-line mixer (Static type in-tube mixer Hi-Mixer, SWJ manufactured by Toray Industries, Inc.). Using a casting apparatus, casting was uniformly performed on a stainless steel band support at a temperature of 35 ° C. and a width of 1800 mm. With the stainless steel band support, the solvent was evaporated until the amount of residual solvent reached 100%, and then peeled off from the stainless steel band support. The peeled cellulose acetate propionate film web was evaporated at 35 ° C, slitted to 1650 mm width, and then 1.3 times at 130 ° C in the TD direction (direction perpendicular to the film transport direction). Stretched. At this time, the residual solvent amount when starting stretching with a tenter was 15%. Then, drying was completed while transporting the drying zone at 120 ° C. and 110 ° C. with a number of rolls, slitting to a width of 1330 mm, a knurling process of width 10 mm and height 5 μm was applied to both ends of the film, and wound on a core. A cellulose acetate propionate film was obtained. The residual solvent amount of the cellulose acetate propionate film was 0.004%, the film thickness was 80 μm, and the winding number was 4000 m. This cellulose acetate propionate film had an in-plane retardation (Ro) of 43 nm and a thickness direction retardation (Rt) of 132 nm.

  The obtained cellulose acetate propionate film was immersed in an aqueous solution of sodium hydroxide having a concentration of 2 mol / liter at 60 ° C. for 2 minutes, washed with water, then dried at 100 ° C. for 10 minutes, and an alkali saponified cellulose acetate propionate film was obtained. Obtained.

Separately from this, a VA type liquid crystal cell was produced by the following procedure. After adding 1% by weight of octadecyldimethylammonium chloride as a coupling agent to an aqueous solution of 3% by weight of polyvinyl alcohol, spin-coating on a glass substrate with an ITO electrode, heat-treating at 160 ° C., and further rubbing treatment. And a vertical alignment film was formed. The rubbing process was performed so that the two glass substrates were in opposite directions. Two glass substrates face each other, the cell gap is 5.5 μm, a liquid crystalline compound mainly composed of ester and ethane is injected, and the product of birefringence of the cell gap and the liquid crystalline compound is VA type 280 nm. A liquid crystal cell was obtained.

  Separately, a 120 μm thick polyvinyl alcohol film was immersed in 100 parts by weight of an aqueous solution containing 1 part by weight of iodine and 4 parts by weight of boric acid, and stretched 4 times at 50 ° C. to form a polarizing film (polarizer). . A polarizing plate was prepared by laminating the alkali saponified cellulose acetate propionate film on both surfaces of the polarizing film with a 5% aqueous solution of completely saponified polyvinyl alcohol as an adhesive.

Example 2
Except for using the fine particle dispersion B and the in-line additive liquid B, a cellulose ester film, a polarizing plate using the same, and a VA liquid crystal cell were prepared in the same manner as in Example 1.

(Fine particle dispersion B)
Aerosil 200V (produced by Nippon Aerosil Co., Ltd.) 10 parts by weight (average primary particle diameter 12 nm, apparent specific gravity 100 g / liter)
Ethanol 75 parts by weight The above materials were stirred and mixed with a dissolver for 30 minutes, and then dispersed with Manton Gorin. 75 parts by weight of methyl acetate was added to the fine particle dispersion with stirring, and the mixture was stirred and mixed with a dissolver for 30 minutes to prepare a fine particle dispersion diluent B.

(Preparation of inline additive solution B)
Methyl acetate 100 parts by weight Tinuvin 109 (manufactured by Ciba Specialty Chemicals) 4 parts by weight Tinuvin 171 (manufactured by Ciba Specialty Chemicals) 4 parts by weight Tinuvin 326 (manufactured by Ciba Specialty Chemicals) 2 parts by weight The solution was completely dissolved and filtered with stirring and heating.

  To this, 10 parts by weight of the fine particle dispersion diluent B was added with stirring, and after further stirring for 30 minutes, 5 parts by weight of cellulose acetate propionate (acetyl group substitution degree 1.9, propionyl group substitution degree 0.8) Was added with stirring, and the mixture was further stirred for 60 minutes, followed by filtration with a polypropylene wind cartridge filter (manufactured by Advantech Toyo Co., Ltd., product number TCW-PPS-1N) to prepare an in-line additive solution B.

Example 3
Except for using the fine particle dispersion C and the in-line additive liquid C, a cellulose-electrified film, a polarizing plate using the same, and a VA liquid crystal cell were prepared in the same manner as in Example 1.

(Fine particle dispersion C)
Aerosil 50 (Nippon Aerosil Co., Ltd.) 10 parts by weight (average primary particle diameter 30 nm, apparent specific gravity 50 g / liter)
Ethanol 75 parts by weight The above materials were stirred and mixed with a dissolver for 30 minutes, and then dispersed with Manton Gorin. 75 parts by weight of methyl acetate was added to the silicon oxide dispersion while stirring, and the mixture was stirred and mixed with a dissolver for 30 minutes to prepare a silicon oxide dispersion dilution C.

(Preparation of inline additive solution C)
Methyl acetate 100 parts by weight Tinuvin 109 (manufactured by Ciba Specialty Chemicals) 4 parts by weight Tinuvin 171 (manufactured by Ciba Specialty Chemicals) 4 parts by weight Tinuvin 326 (manufactured by Ciba Specialty Chemicals) 2 parts by weight The solution was completely dissolved and filtered with stirring and heating.

  To this, 8 parts by weight of the fine particle dispersion diluent B was added with stirring, and further stirred for 30 minutes, and then 5 parts by weight of cellulose acetate propionate (acetyl group substitution degree 1.9, propionyl group substitution degree 0.8). Was added with stirring, and the mixture was further stirred for 60 minutes, followed by filtration with a polypropylene wind cartridge filter (manufactured by Advantech Toyo Co., Ltd., product number TCW-PPS-1N) to prepare an in-line additive solution C.

Example 4
(Preparation of dope solution D)
Cellulose acetate propionate 100 parts by weight (acetyl group substitution degree 1.9, propionyl group substitution degree 0.8)
Triphenyl phosphate 8 parts by weight Ethyl phthalyl ethyl glycolate 2 parts by weight Fine particle dispersion A 4 parts by weight Methyl acetate 245 parts by weight Ethanol 105 parts by weight The solution was filtered using a filter paper (Azumi Filter Paper No. 24, manufactured by Azumi Filter Paper Co., Ltd.) to prepare a dope solution D. In addition, this dope solution D was filtered through a filter medium (trade name Finemet NF, manufactured by Nippon Seisen Co., Ltd.) in the film forming line.

(Preparation of inline additive solution D)
Methyl acetate 100 parts by weight Tinuvin 109 (manufactured by Ciba Specialty Chemicals) 4 parts by weight Tinuvin 171 (manufactured by Ciba Specialty Chemicals) 4 parts by weight Tinuvin 326 (manufactured by Ciba Specialty Chemicals) 2 parts by weight The solution was completely dissolved and filtered with stirring and heating.

  To this was added 5 parts by weight of cellulose acetate propionate (acetyl group substitution degree 1.9, propionyl group substitution degree 0.8) with stirring, and the mixture was further stirred for 60 minutes, and then a polypropylene wind cartridge filter (Advantech Toyo Co., Ltd.). Product number TCW-PPS-1N) and filtered to prepare an in-line additive solution D.

  In the in-line additive liquid line, the in-line additive liquid D was filtered with a filter medium (trade name Finemet NF, manufactured by Nippon Seisen Co., Ltd.). Add 4 parts by weight of filtered inline additive D to 100 parts by weight of filtered dope solution D, and mix thoroughly with an inline mixer (static in-tube mixer Hi-Mixer, SWJ, manufactured by Toray Industries, Inc.) Then, using a belt casting apparatus, it was cast uniformly on a stainless steel band support at a temperature of 35 ° C. and a width of 1800 mm. With the stainless steel band support, the solvent was evaporated until the amount of residual solvent reached 100%, and then peeled off from the stainless steel band support. The peeled cellulose acetate propionate film web was evaporated at 35 ° C, slitted to 1650 mm width, and then 1.3 times at 130 ° C in the TD direction (direction perpendicular to the film transport direction). Stretched. At this time, the residual solvent amount when starting stretching with a tenter was 15%. Then, drying was completed while transporting the drying zone at 120 ° C. and 110 ° C. with a number of rolls, slitting to a width of 1330 mm, a knurling process of width 10 mm and height 5 μm was applied to both ends of the film, and wound on a core. A cellulose acetate propionate film was obtained. The residual solvent amount of the cellulose acetate propionate film was 0.004%, the film thickness was 80 μm, and the winding number was 4000 m. This cellulose acetate propionate film had an in-plane retardation (Ro) of 43 nm and a thickness direction retardation (Rt) of 132 nm.

  The obtained cellulose acetate propionate film was immersed in an aqueous solution of sodium hydroxide having a concentration of 2 mol / liter at 60 ° C. for 2 minutes, washed with water, then dried at 100 ° C. for 10 minutes, and an alkali saponified cellulose acetate propionate film was obtained. Obtained.

Separately from this, a VA type liquid crystal cell was produced by the following procedure. Add 1% by weight of octadecyldimethylammonium chloride as a coupling agent to an aqueous solution of 3% by weight of polyvinyl alcohol, spin coat it on a glass substrate with an ITO electrode, heat-treat at 160 ° C., and then perform a rubbing treatment. And a vertical alignment film was formed. The rubbing process was performed so that the two glass substrates were in opposite directions. Two glass substrates face each other, the cell gap is 5.5 μm, a liquid crystalline compound mainly composed of ester and ethane is injected, and the product of birefringence of the cell gap and the liquid crystalline compound is VA type 280 nm. A liquid crystal cell was obtained.

Separately, a 120 μm thick polyvinyl alcohol film was immersed in 100 parts by weight of an aqueous solution containing 1 part by weight of iodine and 4 parts by weight of boric acid, and stretched 4 times at 50 ° C. to form a polarizing film (polarizer). . A polarizing plate was prepared by laminating the alkali saponified cellulose acetate propionate film on both surfaces of the polarizing film with a 5% aqueous solution of completely saponified polyvinyl alcohol as an adhesive.

Example 5
Cellulose acetate propionate film, polarizing plate and liquid crystal display device in the same manner as in Example 1 except that acetone was used instead of methyl acetate used in the fine particle dispersion, in-line additive solution and dope solution of Example 1. Was made.

Example 6
The cellulose ester used for the dope solution of Example 2 and the in-line additive solution was cellulose triacetate (cellulose triacetate synthesized from linter cotton, number average molecular weight Mn = 148000, weight average molecular weight Mw = 310000, Mw / Mn = 2. 1. A cellulose triacetate film, a polarizing plate, and a liquid crystal display device were produced in the same manner as in Example 2 except that 1, the degree of acetyl group substitution was 2.92).

Comparative Example 1
A cellulose acetate propionate film, a polarizing plate, and a liquid crystal display device were produced in the same manner as in Example 1 except that the dope composition E, the fine particle dispersion E, and the in-line additive solution E were used.

(Preparation of dope solution E)
Cellulose acetate propionate 100 parts by weight (acetyl group substitution degree 1.9, propionyl group substitution degree 0.8)
Triphenyl phosphate 8 parts by weight Ethyl phthalyl ethyl glycolate 2 parts by weight Methyl acetate 200 parts by weight Ethanol 150 parts by weight The above materials are put into a closed container, heated and stirred to completely dissolve, and the solution is filtered. A dope solution E was prepared by filtration using Azumi Filter Paper Co., Ltd. (Azumi Filter Paper No. 24). Moreover, this dope liquid E was filtered with the filter medium (The Nippon Seisen Co., Ltd. make, Finemet NF) in the film forming line.

(Fine particle dispersion E)
SO-C1 (manufactured by Admatechs Co., Ltd.) 10 parts by weight (average primary particle diameter 250 nm)
Ethanol 75 parts by weight The above materials were stirred and mixed with a dissolver for 30 minutes, and then dispersed with Manton Gorin. 75 parts by weight of methyl acetate was added to the silicon oxide dispersion with stirring, and the mixture was stirred and mixed with a dissolver for 30 minutes to prepare a fine particle dispersion diluent E.

(Preparation of inline additive solution E)
Methyl acetate 100 parts by weight Tinuvin 109 (manufactured by Ciba Specialty Chemicals) 4 parts by weight Tinuvin 171 (manufactured by Ciba Specialty Chemicals) 4 parts by weight Tinuvin 326 (manufactured by Ciba Specialty Chemicals) 2 parts by weight The solution was completely dissolved and filtered with stirring and heating. To this, 20 parts by weight of the fine particle dispersion diluent E was added with stirring, and further stirred for 30 minutes, and then 5 parts by weight of cellulose acetate propionate (acetyl group substitution degree 1.9, propionyl group substitution degree 0.8). Was added with stirring, and the mixture was further stirred for 60 minutes, and then filtered through a polypropylene wind cartridge filter (manufactured by Advantech Toyo Co., Ltd., product number TCW-PPS-1N) to prepare an in-line additive solution E.

Comparative Example 2
A cellulose acetate propionate film, a polarizing plate, and a liquid crystal display device were produced in the same manner as in Comparative Example 1 except that the in-line additive solution F was used.

(Preparation of inline additive solution F)
Methyl acetate 100 parts by weight Tinuvin 109 (manufactured by Ciba Specialty Chemicals) 8 parts by weight Tinuvin 171 (manufactured by Ciba Specialty Chemicals) 8 parts by weight Tinuvin 326 (manufactured by Ciba Specialty Chemicals) 4 parts by weight The solution was completely dissolved and filtered with stirring and heating. To this, 40 parts by weight of the fine particle dispersion diluent E was added with stirring, and after further stirring for 30 minutes, 5 parts by weight of cellulose acetate propionate (acetyl group substitution degree 1.9, propionyl group substitution degree 0.8) Was added with stirring, and the mixture was further stirred for 60 minutes, followed by filtration with a polypropylene wind cartridge filter (manufactured by Advantech Toyo Co., Ltd., product number TCW-PPS-1N) to prepare an in-line additive solution F.

  The in-line additive solution F was cast by adding 2 parts by weight to the dope solution A.

Comparative Example 3
A cellulose acetate propionate film, a polarizing plate, and a liquid crystal display device were produced in the same manner as in Comparative Example 1 except that the inline additive solution G was used.

(Preparation of inline additive solution G)
Methyl acetate 100 parts by weight Tinuvin 109 (manufactured by Ciba Specialty Chemicals) 1 part by weight Tinuvin 171 (manufactured by Ciba Specialty Chemicals) 1 part by weight Tinuvin 326 (manufactured by Ciba Specialty Chemicals) 0.5 part by weight The solution was put into a sealed container, heated, stirred and completely dissolved and filtered.

  To this was added 5 parts by weight of the fine particle dispersion diluent E with stirring, and further stirred for 30 minutes, and then 5 parts by weight of cellulose acetate propionate (acetyl group substitution degree 1.9, propionyl group substitution degree 0.8). Was added with stirring, and the mixture was further stirred for 60 minutes, and then filtered through a polypropylene wind cartridge filter (manufactured by Advantech Toyo Co., Ltd., product number TCW-PPS-1N) to prepare an in-line additive solution F. The in-line additive solution F was cast by adding 16 parts by weight to the dope solution A.

  Next, for each cellulose ester film obtained in Examples 1 to 6 and Comparative Examples 1 to 3 of the present invention, 1. average particle diameter in cellulose ester film; 2. average particle diameter in the fine particle dispersion; 3. molecular weight of aggregate, radius of inertia, second virial coefficient, 4. UV transmittance of the film 5. Variation in the number of protrusions on the film surface. Spot defects, 7. 7. bright spot foreign matter, and The image defects in the liquid crystal display device were measured, and the obtained results are shown in Table 1 below.

<Measurement method>
1. Average particle diameter in cellulose ester film The particles were observed with a scanning electron microscope (5000 times magnification), and the diameter of a circle circumscribing the particles was defined as the particle diameter. Also, 100 particles were observed at different locations, and the average value was taken as the average particle size.

2. Average particle diameter in fine particle dispersion The fine particle dispersion was measured at 25 ° C. with a dynamic light scattering particle size measuring device-HPPS manufactured by MALVERN, and the obtained Z-average value was defined as the average particle size.

3. Measurement of molecular weight of aggregate, radius of inertia, and second virial coefficient Measured using a static light scattering method. These measurements are made in a dilute region for the convenience of the apparatus, but these measured values reflect the behavior of the dope in the high concentration region.

  First, cellulose ester was dissolved in a solvent used for the dope to prepare 0.1 wt%, 0.2 wt%, 0.3 wt%, and 0.4 wt% solutions. In order to prevent moisture absorption, the cellulose acylate was dried at 120 ° C. for 2 hours, and measured in an environment of 25 ° C. and 10% RH. The dissolution method was carried out according to the method employed at the time of dope dissolution (room temperature dissolution method, cooling dissolution method, high temperature dissolution method).

  Subsequently, these solutions and the solvent were filtered through a 0.2 μm Teflon (registered trademark) filter. And about the filtered solution, static light scattering was measured by 10 degree intervals from 30 degree | times to 140 degree | times in 25 degreeC using the light-scattering measuring apparatus (The Otsuka Electronics Co., Ltd. make, DLS-700). The obtained data was analyzed by the BERRY plot method. In addition, the refractive index required for this analysis uses the value of the solvent calculated | required with the Abbe refracting system, and the refractive index concentration gradient (dn / dc) uses a differential refractometer (made by Otsuka Electronics Co., Ltd., DRM-1021). The measurement was performed using the solvent and the solution used for the light scattering measurement.

4). Measurement of UV transmittance of film Using a spectrophotometer (Spectrophotometer U-3200, manufactured by Hitachi, Ltd.), the spectrum of the film sample was measured to determine the transmittance at 380 nm. The wound-up resin film was rewound and measured by sampling at 100 mm intervals in an area of 5 m length × 1 m width. The variation of the maximum value and the minimum value was calculated as a ratio with respect to the average value.

5). Measurement of variation in the number of protrusions on the film surface Using a three-dimensional surface structure analysis microscope (ZYGO, New View-5010), the surface roughness of the film sample opposite to the metal support is measured and attached analysis The number of protrusions having a height equal to or higher than three times Ra measured by software was calculated, and the number of protrusions per 1 mm 2 was calculated. The wound resin film is unwound and measured by sampling at 100 mm intervals in an area of 5 m length x 1 m width. For the average value, the variation between the maximum value and the minimum value was calculated as a ratio.

6). Measurement of Spot Defect The film sample was visually inspected at an area of 1 m ² every 2600 m, the spot foreign matter was sampled, and the number of foreign matters having a size of 50 μm or more was counted with a microscope. If an average value of five inspections is taken and 0.5 pieces / m ² or less, there is no practical problem.

7). Measurement of Bright Spot Foreign Material A polarizing plate was placed at a crossed Nicol position, a film sample was sandwiched between them, and the number of foreign materials having a size of 10 μm or more in a 100 mm square film size was measured.

8). Measurement of image defects in the liquid crystal display device The obtained liquid crystal display device was subjected to white display and black display with a video pattern generator (manufactured by EMT Co., product number VG365N). Defects such as distortion were visually observed.

  As is clear from the results of Table 1 above, in the cellulose ester films according to Examples 1 to 6 of the present invention, the average particle diameter of the granular material in the film is b, the average primary particle diameter of the fine particles is c, and the fine particle dispersion The ratio of b / c and the ratio of b / a, aggregate molecular weight, inertial square radius, and second virial coefficient are all within the scope of the present invention, where the average particle diameter is a. On the other hand, in Comparative Examples 1-3, these values were all outside the scope of the present invention.

  Furthermore, in the cellulose ester films according to Examples 1 to 6 of the present invention, the variation in the number of protrusions (%) on the film surface is very small, the uniformity of various additives is maintained, and the optical characteristics and slipperiness are within the film plane. The “variation” of the was able to be reduced. In addition, the number of spot defects, bright spot foreign matter, and image defects in the liquid crystal display device are all small, and it can sufficiently cope with the rapid spread and large screen of liquid crystal televisions due to diversification of liquid crystal display devices. Met.

  Moreover, in consideration of environmental safety when producing these cellulose ester films, despite the use of non-chlorine organic solvents, the desired optical properties and the slipperiness between the films are maintained, and images are obtained. A cellulose ester film free from defects could be produced.

  On the other hand, the cellulose ester films according to Comparative Examples 1 to 3 all have large variations (%) in the number of protrusions on the film surface, and also have many spot defects, bright spot foreign matter, and image defects in the liquid crystal display device. It can be seen that the quality of the cellulose ester film is inferior.

Claims (21)

After dispersing fine particles as a matting agent in a solvent in advance and mixing with a cellulose ester solution, the mixed solution is cast on a support, and after initial drying on the support, the web is peeled off from the support and post-drying A cellulose ester film obtained by a solution casting film forming method, wherein the average particle diameter of the granular material in the cellulose ester film is b, and the average primary particle diameter of the fine particles is c,
6 ≦ b / c ≦ 90
A cellulose ester film characterized by satisfying the relational expression: When the average particle diameter of the granular material in the fine particle dispersion is a, and the average particle diameter of the granular material in the cellulose ester film is b,
2 ≦ b / a ≦ 8
The cellulose ester film according to claim 1, wherein:   The cellulose ester film according to claim 1 or 2, wherein the solvent used for dispersing the fine particles is a non-chlorine organic solvent.   The cellulose ester film according to any one of claims 1 to 3, wherein the solvent for dissolving the cellulose ester is a non-chlorine organic solvent. The aggregate molecular weight obtained by diluting the cellulose ester solution dissolved in a solvent to 0.1 to 1.0% by weight and measuring by static light scattering method is 50,000 to 1,000,000, the inertial square radius is 20 to 100 nm, the second A virial coefficient is 2.0 * 10 < ^-4 > -2.0 * 10 < ^-3 >, The cellulose-ester film as described in any one of Claims 1-4 characterized by the above-mentioned.   After the UV absorber is dissolved in a solvent in advance and mixed with the cellulose ester solution, the mixed solution is cast on the support, and after initial drying on the support, the web is peeled off from the support and post-drying is performed. A cellulose ester film obtained by a solution casting film forming method, wherein the concentration of the ultraviolet absorbent in the ultraviolet absorbent solution is 3 to 20% by weight.   The cellulose ester film according to claim 6, wherein 2 to 10% by weight of the cellulose ester resin is contained in the ultraviolet absorbent solution.   The cellulose ester film according to claim 6 or 7, wherein the solvent used in the ultraviolet absorbent solution is a non-chlorine organic solvent.   The cellulose ester film according to any one of claims 6 to 8, further comprising an ultraviolet absorber by adding the ultraviolet absorber solution in-line to the cellulose ester solution.   The fine particles as a matting agent are dispersed in a solvent in advance, the ultraviolet absorber is dissolved in a solvent in advance, the fine particle dispersion and the ultraviolet absorbent solution are mixed with the cellulose ester solution, and then the mixed solution is flowed onto the support. After the initial drying on the support, the cellulose ester film is obtained by a solution casting film forming method in which the web is peeled off from the support and post-drying is performed, in which the fine particles are dispersed and the UV absorber is dissolved. The cellulose ester film is characterized in that all of the solvents used in the cellulose ester solution are non-chlorine organic solvents. Fine particles as a matting agent are dispersed in a solvent in advance, the fine particle dispersion is mixed with a cellulose ester solution, the mixed solution is cast onto a support, and the web is peeled from the support after initial drying on the support. And a method of producing a cellulose ester film by a solution casting film forming method in which post-drying is performed, wherein the average particle diameter in the cellulose ester film is b, and the average primary particle diameter of the fine particles is c.
6 ≦ b / c ≦ 90
The manufacturing method of the cellulose-ester film characterized by satisfy | filling these relational expressions. Fine particles as a matting agent are dispersed in a solvent in advance, the fine particle dispersion is mixed with a cellulose ester solution, the mixed solution is cast onto a support, and the web is peeled from the support after initial drying on the support. And a method of producing a cellulose ester film by a solution casting film forming method in which post-drying is performed, wherein the average particle diameter of the granular material in the fine particle dispersion is a, and the average particle diameter of the granular material in the cellulose ester film is b
2 ≦ b / a ≦ 8
The method for producing a cellulose ester film according to claim 11, wherein the following relational expression is satisfied.   The method for producing a cellulose ester film according to claim 11 or 12, wherein the solvent used for dispersing the fine particles is a non-chlorine organic solvent.   The method for producing a cellulose ester according to claim 11, wherein the solvent for dissolving the cellulose ester is a non-chlorine organic solvent.   Dissolve the UV absorber in a solvent in advance, mix the UV absorber solution with the cellulose ester solution, cast the mixed solution onto the support, and peel the web from the support after initial drying on the support. A cellulose ester film is produced by a solution casting film forming method in which post-drying is performed, wherein the ultraviolet absorbent concentration in the ultraviolet absorbent solution is 3 to 20% by weight. A method for producing a film.   The method for producing a cellulose ester film according to claim 15, wherein 2 to 10 wt% of the cellulose ester resin is contained in the ultraviolet absorbent solution.   The method for producing a cellulose ester according to claim 15 or 16, wherein the solvent used in the ultraviolet absorbent solution is a non-chlorine organic solvent.   The method for producing a cellulose ester film according to claim 15, wherein the ultraviolet absorber is contained by adding the ultraviolet absorber solution in-line to the cellulose ester solution.   The fine particles as a matting agent are dispersed in a solvent in advance, the ultraviolet absorber is dissolved in a solvent in advance, the fine particle dispersion and the ultraviolet absorbent solution are mixed with the cellulose ester solution, and then the mixed solution is flowed onto the support. After the initial drying on the support, the web is peeled off from the support, and the cellulose ester film is produced by a solution casting film forming method in which post-drying is performed, which is contained in the dope to be cast. A method for producing a cellulose ester film, which is produced using a dope having a chlorinated organic solvent content of 1% by weight or less.   A polarizing plate comprising the cellulose ester film according to claim 1 bonded to at least one surface of a polarizing film.   A liquid crystal display device using the polarizing plate according to claim 20.