JP2005103815A - Transparent resin film and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To hold the uniformity of various additives to be used, to reduce the in-plane irregularity of optical characteristics or slip properties and to eliminate a spot flaw capable of becoming an image flaw, in a transparent resin film, especially a cellulose ester film suitable as the protective film for the polarizing plate of a liquid crystal display device or a norbornene resin film suitable as a phase difference compensation film. <P>SOLUTION: A resin solution based on a resin mainly comprising a cellulose ester or a norbornene resin is filtered and a part of the filtered resin solution is mixed with additives such as an ultraviolet absorber, fine particles and the like and a solvent to prepare an additive solution which is, in turn, added to the principal part of the resin solution based on a resin mainly comprising the cellulose ester or the norbornene resin in a predetermined ratio to prepare a dope for the transparent resin film. The transparent resin film is manufactured by a solution casting film forming method using this dope. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a transparent resin film, particularly a cellulose ester film suitable as a protective film for a polarizing plate of a liquid crystal display (LCD) or a norbornene resin film suitable as a retardation compensation film, and a method for producing these transparent resin films. Is.

  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 PDAs (personal digital assistants), it is necessary to include a UV absorber in the protective film for polarizing plates in order to prevent the polarizer from deteriorating.

  As a protective film for such a polarizing plate, a cellulose ester film such as triacetyl cellulose (TAC) is suitable because of its low birefringence and is often used. On the other hand, norbornene-based resin films have excellent characteristics such as heat resistance, low specific gravity, low birefringence, and low photoelastic coefficient, and therefore are being used as retardation compensation films.

  By the way, cellulose triacetate (TAC) film is mainly used as a protective film for polarizing plates currently used in LCDs, but the outermost surface is especially widespread due to the widespread use of televisions and monitors and their large screens. In the film used for the above, high flatness is required, and when it reaches a spot defect, the defect becomes an image defect, which leads to deterioration of the quality of the LCD.

  In addition, resin films used in LCDs tend to stick to each other as the transparency and smoothness of the film are maintained, and as a handling property during film formation of these resin films and surface processing on resin films, Fine particles are added to the glass so as to improve the handling property and stabilize the winding property without impairing transparency and providing slipperiness.

  In particular, as the resin film becomes thinner, the film is deformed during the winding process, or the films are stuck together for a long time with the film wound in a long length, or blocking occurs in severe cases. There are things to do. When this film is used in the production process of a polarizing plate, there is a problem that a portion where the films are bonded to each other is deformed, and causes uneven bonding with a polarizer or coating unevenness when applied.

  In order to give the film these characteristics and to solve the above-mentioned problems of the prior art, various additives are used in the resin film.

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 size of 0.5 μm to 1.0 μm are added to the surface. A cellulose triacetate film containing 1% to 0.15% by weight is disclosed.

  However, in the technique disclosed in Patent Document 1 described above, when an attempt is made to increase the addition amount of fine particles having an average particle size of 0.5 μm or more, the addition amount of an ultraviolet absorber or cellulose triacetate also increases. 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 the ultraviolet absorber is necessary, it is difficult to control the particle size of the aggregate in the case of fine particles formed with secondary particle aggregates, and the above spot defects occur frequently. .

  In the technique disclosed in Patent Document 1, as a method for adding fine particles to the film, a solution of cellulose acetate and a fine particle dispersion containing fine particles are separately prepared and mixed with a static mixer. . In the case of such a method, uniform mixing of a plurality of additives becomes an issue, especially when the solubility of the resin decreases with a decrease in temperature in winter, etc., the mixing state of additives such as fine particles and ultraviolet absorbers As a result, problems such as generation of aggregates that cause spot defects, minute unevenness of the ultraviolet absorber, and variation in the distribution of fine particles occurred.

  The object of the present invention is to solve the above-mentioned problems of the prior art, keep the uniformity of various additives in the transparent resin film used in accordance with the diversification of liquid crystal display devices, and improve the optical characteristics and slipperiness. It is an object of the present invention to provide a transparent resin film and a method for manufacturing the same that can reduce the variation in the thickness and eliminate the spot defects that can be image defects.

  In order to achieve the above object, the invention according to claim 1 of the present invention is a method for producing a transparent resin film of a cellulose ester or a norbornene resin by a solution casting film forming method, which comprises a cellulose ester or a norbornene A dope of a transparent resin film is prepared by adding inline an additive solution containing a resin composed of a cellulose ester or norbornene resin, an ultraviolet absorber, and fine particles to a resin solution composed mainly of a resin. In the process, the resin solution mainly composed of the cellulose ester or norbornene resin is filtered, and a part of the filtered resin solution is mixed with an additive such as an ultraviolet absorber and fine particles and a solvent. A solution is prepared, and the additive solution is prepared from the cellulose ester or norbornene resin. A dope of a transparent resin film is prepared by adding a predetermined ratio to a main part of a resin solution containing a resin as a main component, and a transparent resin film is produced by a solution casting film forming method using this dope It is characterized by that.

  Invention of Claim 2 of this invention is a manufacturing method of the transparent resin film of Claim 1 above, Comprising: The resin solution which has resin which consists of a cellulose ester or a norbornene-type resin as a main component is filtered, and after filtration A pipe that flows in to mix a part of the resin solution with an additive such as an ultraviolet absorber and fine particles and a solvent is a pipe having an inner diameter of 200 mm or less.

  Invention of Claim 3 of this invention is a manufacturing method of the transparent resin film of said Claim 1 or 2, Comprising: The resin solution which has resin which consists of a cellulose ester or a norbornene-type resin as a main component is filtered, and filtration is carried out. A solution inflow restricting plate having at least two solution circulation holes with a diameter of 50 mm or less is provided at a discharge port of a pipe into which a part of the later resin solution is mixed with an ultraviolet absorber, an additive such as fine particles, and a solvent. It is characterized by being provided.

Invention of Claim 4 of this invention is a manufacturing method of the transparent resin film as described in any one of the said Claims 1-3, Comprising: Resin consisting of a cellulose ester or a norbornene-type resin is a main component. When the boiling point of the solvent contained in the resin solution is A ° C., and the temperature at which a part of the resin solution is mixed with an additive such as an ultraviolet absorber and fine particles and the solvent after filtration is B ° C.,
A-10 ≦ B ≦ A
It is characterized in that the relational expression represented by

  Invention of Claim 5 of this invention is a transparent resin film manufactured by the manufacturing method of the transparent resin film as described in any one of the said Claims 1-4, Comprising: Per unit film thickness in 380 nm The variation in the value of the ultraviolet transmittance when measuring the ultraviolet transmittance of 100 mm in the width direction and the longitudinal direction at intervals of 100 mm is within ± 5% of the average value.

  Invention of Claim 6 of this invention is a transparent resin film manufactured by the manufacturing method of the transparent resin film as described in any one of the said Claims 1-4, Comprising: For casting at the time of film forming The number of protrusions per unit area of protrusions having a height of 3 times or more relative to the surface roughness Ra on the film surface opposite to the support is the number of protrusions when measured in the width direction and the longitudinal direction at intervals of 100 mm. The variation is characterized by being within ± 15% of the average value.

  The invention according to claim 1 of the present invention is a method for producing a transparent resin film of cellulose ester or norbornene resin by a solution casting film forming method as described above, and is a resin comprising cellulose ester or norbornene resin In preparing a dope for a transparent resin film, an additive solution containing a cellulose ester or norbornene resin, an ultraviolet absorber, and an additive solution containing fine particles is added in-line to a resin solution mainly containing A resin solution mainly composed of an ester or norbornene resin is filtered, and a part of the filtered resin solution is mixed with an additive such as an ultraviolet absorber and fine particles and a solvent to prepare an additive solution. The additive solution is mainly composed of a resin comprising the above cellulose ester or norbornene resin. A dope of a transparent resin film is prepared by adding it to a main part of the resin solution at a predetermined ratio, and a transparent resin film is produced by a solution casting film forming method using this dope Therefore, according to the present invention, a resin solution mainly composed of a resin comprising cellulose ester or norbornene resin is filtered, and a part of the filtered resin solution is mixed with an additive such as an ultraviolet absorber and fine particles and a solvent. Since the additive solution is prepared by mixing with the resin, the solubility of the resin to be added can be increased, the mixing state of the fine particles and the UV absorber can be improved, and the liquid crystal display device is diversified. As a result, in the transparent resin film used, the uniformity of various additives is maintained, the variation in the optical properties and slippage in the surface is reduced, and spot defects that can become image defects An effect that can be eliminated.

  Invention of Claim 2 of this invention is a manufacturing method of the cellulose-ester film of said Claim 1, Comprising: The resin solution which has resin which consists of cellulose ester or a norbornene-type resin as a main component is filtered, and after filtration A pipe that flows in to mix a part of the resin solution with an additive such as an ultraviolet absorber and fine particles and a solvent is a pipe having an inner diameter of 200 mm or less. Since the inflow diameter of the resin solution is reduced, the dissolution time is short, and it is possible to uniformly dissolve the resin solution.

  Invention of Claim 3 of this invention is a manufacturing method of the transparent resin film of said Claim 1 or 2, Comprising: The resin solution which has resin which consists of a cellulose ester or a norbornene-type resin as a main component is filtered, and filtration is carried out. A solution inflow restricting plate having at least two solution circulation holes with a diameter of 50 mm or less is provided at a discharge port of a pipe into which a part of the later resin solution is mixed with an ultraviolet absorber, an additive such as fine particles, and a solvent. According to the present invention, since the inflow diameter of the resin solution at the time of addition is further reduced, the dissolution time is short and the effect of uniform dissolution can be achieved.

Invention of Claim 4 of this invention is a manufacturing method of the transparent resin film as described in any one of the said Claims 1-3, Comprising: Resin consisting of a cellulose ester or a norbornene-type resin is a main component. When the boiling point of the solvent contained in the resin solution is A ° C., and the temperature at which a part of the resin solution is mixed with an additive such as an ultraviolet absorber and fine particles and the solvent after filtration is B ° C.,
A-10 ≦ B ≦ A
According to the present invention, the resin solution temperature when adding the resin solution is set to a temperature close to the boiling point of the solvent dissolving the resin. After all, there is an effect that the dissolution time is short and it can be uniformly dissolved.

  Invention of Claim 5 of this invention is a transparent resin film manufactured by the manufacturing method of the transparent resin film as described in any one of the said Claims 1-4, Comprising: Per unit film thickness in 380 nm Variation of the value of the ultraviolet transmittance when measured in the width direction and the longitudinal direction at intervals of 100 mm is within ± 5% of the average value. Accordingly, for example, there is an effect that the degree of deterioration of the polarizing plate in the liquid crystal display device does not vary depending on the location, and distortion and image display unevenness do not occur.

  Invention of Claim 6 of this invention is a transparent resin film manufactured by the manufacturing method of the transparent resin film as described in any one of the said Claims 1-4, Comprising: For casting at the time of film forming The number of protrusions per unit area of protrusions having a height of 3 times or more relative to the surface roughness Ra on the film surface opposite to the support is the number of protrusions when measured in the width direction and the longitudinal direction at intervals of 100 mm. The variation is within ± 15% with respect to the average value. According to the present invention, the slipperiness between the films is not locally different, and the film is deformed when the film is wound. Therefore, it is possible to prevent the occurrence of image defects due to such deformation.

  Hereinafter, the present invention will be specifically described.

  As a result of intensive research in order to solve the above-mentioned problems of the prior art, the inventors of the present invention have added cellulose and a UV absorber as a method for adding fine particles and an ultraviolet absorber into a transparent resin film made of cellulose ester or norbornene resin. A method is employed in which an additive solution containing these resins, ultraviolet absorbers, and fine particles is added to a resin solution mainly composed of an ester or norbornene resin. In this case, it is necessary to increase the solubility of these resins to be added in order to improve the mixing state of the fine particles and the ultraviolet absorber.

As a means for increasing the solubility of these resins, in the present invention, firstly, a resin solution mainly composed of a cellulose ester or norbornene resin is filtered, and a part of the filtered resin solution is removed. The additive solution is prepared by mixing with an additive such as an ultraviolet absorber and fine particles and a solvent. And this additive solution is added to the main part of the resin solution which has as a main component the resin which consists of the said cellulose ester or norbornene-type resin in a predetermined ratio. Second, in order to filter a resin solution mainly composed of a cellulose ester or norbornene resin, and to mix a part of the filtered resin solution with an additive such as an ultraviolet absorber and fine particles and a solvent. The inner diameter of the inflowing pipe is set to 200 mm or less. Third, a solution flow regulating plate having at least two solution flow holes having a diameter of 50 mm or less is provided at the discharge port of the pipe. Fourth, the boiling point of a solvent contained in a resin solution mainly composed of a resin comprising cellulose ester or norbornene resin is A ° C., and after a part of the resin solution is filtered, additives such as an ultraviolet absorber and fine particles, When the temperature when mixed with the solvent is B ° C,
A-10 ≦ B ≦ A More preferably,
A-5 ≦ B ≦ A
So that the temperature of the resin solution when adding the resin solution is set to a temperature close to the boiling point of the solvent in which the resin is dissolved. Combined.

As described above, a cellulose ester or norbornene resin film with less foreign matter can be obtained by filtering a part of a resin solution obtained by dissolving a cellulose ester or norbornene resin in a solvent using a filter paper as described below. it can. 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, a filter paper having a drainage time of 30 sec or more is used and a filtration pressure is 12 kg / cm ² or less, and more preferably, a filter paper having a drainage time of 40 sec or more is used and the filtration pressure is 10 kg / cm ² or less. That is. 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.

  According to the method of the present invention, when the resin is added to the additive solution in the state of the resin solution rather than the resin itself, the resin dissolves quickly and uniformly. Further, when the inner diameter of the pipe into which a part of the resin solution flows is set to 200 mm or less, or by adding a solution flow regulating plate having at least two solution flow holes having a diameter of 50 mm or less at the discharge port of the pipe, Since the inflow diameter of the resin solution becomes small, the dissolution time is short and the resin solution can be uniformly dissolved. Alternatively, by setting the resin solution temperature when adding the resin solution to a temperature close to the boiling point of the solvent in which the resin is dissolved, the dissolution time is short and the resin solution can be uniformly dissolved.

  The transparent resin film according to the present invention has a variation in the value of the ultraviolet transmittance when the ultraviolet transmittance per unit film thickness at 380 nm is measured in the width direction and the longitudinal direction at intervals of 100 mm with respect to the average value. It is characterized by being within ± 5%, but here, if the dispersion of the UV transmittance exceeds 5%, the degree of deterioration of the polarizing plate in the liquid crystal display device varies depending on the location, and distortion may occur. In some cases, image display becomes uneven, which is not preferable.

  Moreover, in the transparent resin film of the present invention, the number of protrusions per unit area having a height of 3 times or more with respect to the surface roughness Ra on the film surface opposite to the casting support at the time of film formation, The variation in the number of protrusions when measured in the width direction and the longitudinal direction at 100 mm intervals is within ± 15% of the average value. Here, the surface roughness Ra is 3%. If the variation in the number of double protrusions exceeds 15%, the slipperiness between the films is locally different, and deformation tends to occur when the film is wound, which leads to image defects, which is not preferable.

  As described above, in the transparent resin film of the present invention, the in-plane variation of the ultraviolet transmittance per unit film thickness is within 5% of the average value, and the surface roughness is caused by the distribution state of the fine particles (mat agent). The variation in the number of protrusions 3 times the height of Ra is kept within 15% of the average value, but these are all uniformly dissolved by the combination of the above-described methods for producing the transparent resin film of the present invention. It is achieved by obtaining a state.

  In addition, in the above, the dispersion | variation in the ultraviolet transmittance of a transparent resin film measures the spectral spectrum of a transparent resin film sample, for example using a spectral-spectrum measuring device, and calculates | requires the transmittance | permeability in 380 nm. The taken transparent resin film is unwound, sampled and measured at an interval of 100 mm, for example, with an area of length 5 m × width 1 m, and the variation between the maximum value and the minimum value is calculated as a ratio with respect to the average value.

The variation in the number of protrusions on the surface of the transparent resin film is measured by measuring the surface roughness Ra of the surface of the formed transparent resin film sample opposite to the metal support using, for example, a three-dimensional surface structure analysis microscope. The number of protrusions having a height equal to or greater than three times the measured surface roughness Ra is calculated, and the number of protrusions per 1 mm ² is calculated. The wound transparent resin film is unwound, sampled and measured at an interval of 100 mm, for example, with an area of length 5 m × width 1 m, and the variation between the maximum value and the minimum value is calculated as a ratio with respect to the average value.

  Next, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows an apparatus for carrying out a method for producing a transparent resin film of cellulose ester or norbornene resin by the solution casting film forming method of the present invention.

  Referring to FIG. 1, first, a resin solution containing a resin composed of a cellulose ester or a norbornene resin as a main component is prepared in a melting pot (1). The resin solution is then discharged from the flow pipe (2) connected to the bottom of the dissolution tank (1), transferred by the operation of the liquid feed pump (3), and filtered through the filter (4).

  On the other hand, an additive solution containing a cellulose ester or norbornene-based resin, an ultraviolet absorber, and fine particles is prepared in a dissolution vessel (6). At this time, a part of the resin solution after filtration is sent to the melting pot (6) by the feed pipe (5) branched downstream from the filter (4) of the feed pipe (2), where the A part of the filtered resin solution is mixed with an additive such as an ultraviolet absorber and fine particles and a solvent to prepare an additive solution. This additive solution is then discharged from the flow pipe (7) connected to the bottom of the dissolution vessel (6), transferred by the operation of the liquid feed pump (8), and filtered through the filter (9). The resin solution mainly composed of a cellulose ester or norbornene resin that is fed by the feed pipe (2) is added at a predetermined ratio and mixed by the static mixer (10). As a result, a dope of the transparent resin film is prepared.

  Further, the dope of the transparent resin film is cast on the support (12) by the casting die (11) of the solution casting film forming apparatus, and then heated to remove a part of the solvent ( After drying on the support), the film is peeled off from the support (12), and the peeled film is dried (film drying process) to obtain a cellulose ester or norbornene resin film. As the support (12) in the casting process, a support having a mirror-finished belt-like or drum-like stainless steel as illustrated is used.

  Further, as shown in detail in FIG. 2, in the method for producing a transparent resin film of the present invention, a resin solution mainly composed of a cellulose ester or norbornene resin is filtered, and a part of the filtered resin solution is obtained. It is preferable that the pipe (5) that flows in for mixing with the ultraviolet absorber, additives such as fine particles, and the solvent is a pipe having an inner diameter of 200 mm or less.

  In the method for producing a transparent resin film of the present invention, a solution inflow restricting plate (13) having at least two solution circulation holes (14) having a diameter of 50 mm or less is provided at the discharge port of the pipe (5). Preferably it is.

Furthermore, in the method for producing a transparent resin film of the present invention, the boiling point of a solvent contained in a resin solution mainly composed of a cellulose ester or norbornene resin is A ° C., and after a part of the resin solution is filtered, When the temperature at the time of mixing with an additive such as an ultraviolet absorber and fine particles and a solvent is B ° C,
A-10 ≦ B ≦ A More preferably,
A-5 ≦ B ≦ A
It is preferable that the relational expression represented by

  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 particularly preferable, and a base strength of a bound acetic acid amount of 58% to 62.5% is strong and more 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 a drum because of high productivity efficiency. When the ratio of cellulose triacetate synthesized from cotton linter is 60% by weight or more and the effect of releasability becomes remarkable, 60% by weight or more is preferable, more preferably 85% by weight or more, and further, it can be used alone. Most preferred.

  On the other hand, in the method for producing a norbornene-based resin film of the present invention, the norbornene-based resin that is a main raw material of the norbornene-based resin film is a known resin, for example, JP-A-3-14882 and JP-A-3-122137. It is described in the gazette.

  Examples of the monomer constituting the norbornene resin film include norbornene, 5-methyl-2-norbornene, 5-ethyl-2-norbornene, 5-butyl-2-norbornene, 5-ethylidene-2-norbornene, and 5-methoxy. Carbonyl-2-norbornene, 5,5-dimethyl-2-norbornene, 5-cyano-2-norbornene, 5-methyl-5-methoxycarbonyl-2-norbornene, 5-phenyl-2-norbornene, 5-phenyl-5 -Methyl-2-norbornene and the like.

  The norbornene-based resin is, for example, (A) a resin obtained by hydrogenating a ring-opening polymer or ring-opening copolymer of a norbornene-based monomer, if necessary, such as maleic acid addition or cyclopentadiene addition, (B) Resin obtained by addition polymerization of norbornene monomer, (C) Resin obtained by addition polymerization of norbornene monomer and olefin monomer such as ethylene or α-olefin, (D) Norbornene monomer and cyclopentene, cyclooctene, 5 Examples include resins obtained by addition polymerization with cyclic olefin monomers such as 1,6-dihydrodicyclopentadiene, and modified products of these resins. These polymerizations can be carried out by conventional methods.

  Although it does not specifically limit as a plasticizer which can be used by this invention, In a phosphate ester type | system | group, a triphenyl phosphate, a tricresyl phosphate, a cresyl diphenyl phosphate, an octyl diphenyl phosphate, a diphenyl biphenyl phosphate, a trioctyl phosphate, a tributyl phosphate In the phthalate ester system, diethyl phthalate, dimethoxyethyl phthalate, dimethyl phthalate, dioctyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate, etc., in the glycolate system, triacetin, tributyrin, butyl phthalyl butyl glycolate, ethyl Use phthalyl ethyl glycolate, methyl phthalyl ethyl glycolate, butyl phthalyl butyl glycolate alone or in combination It is preferred.

  If necessary, two or more kinds of plasticizers may be used in combination. In this case, the use ratio of the phosphate ester type plasticizer is 50% or less to hydrolyze the cellulose ester or norbornene resin film. It is preferable because it is difficult to cause and has excellent durability.

  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.

  In the present invention, in order to further bring the water absorption rate and the water content within a specific range, the addition amount of the plasticizer is preferably 3% by weight to 30% by weight with respect to the cellulose ester or norbornene resin. More preferably, it is 10 to 25% by weight, and more preferably 15 to 25% by weight. If it exceeds 30% by weight, the mechanical strength and dimensional stability deteriorate.

  An ultraviolet absorber is used for the cellulose ester or norbornene resin film of the present invention. 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, benzophenone 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.

  In the present invention, preferably used ultraviolet absorbers include benzotriazole ultraviolet absorbers and benzophenone ultraviolet absorbers. The embodiment in which the benzotriazole-based ultraviolet absorber is added to the cellulose ester or norbornene-based resin film is particularly preferable because unnecessary coloring is reduced.

  In addition, as the ultraviolet absorber, a triazine-based ultraviolet absorber or a polymer ultraviolet absorber described in JP-A-2001-154017 and JP-A-6-130226 previously proposed by the present applicant is also preferable. Used.

  In the present invention, the ultraviolet absorber is added by dissolving the ultraviolet absorber with other additives and resin in an organic solvent such as alcohol, methylene chloride, and dioxolane, and then adding it to the resin solution. Those that do not dissolve in an organic solvent such as inorganic powder are dispersed in an organic solvent and a cellulose ester or norbornene resin using a dissolver or a sand mill, and then added to the resin solution.

  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, based on the weight% of the cellulose ester or norbornene resin. Preferably it is 0.8 weight%-2.0 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, cellulose ester solvents include, for example, lower alcohols such as methanol, ethanol, n-propyl alcohol, iso-propyl alcohol, n-butanol, lower aliphatic hydrocarbon chlorides such as cyclohexanedioxane, and methylene chloride. Things can be used.

  As the solvent ratio, for example, methylene chloride is preferably 70% by weight to 95% by weight, and other solvents are preferably 30% by weight to 5% by weight. The concentration of the cellulose ester is preferably 10% by weight to 50% by weight. The heating temperature with the addition of the solvent is preferably in the range of not less than the boiling point of the solvent used and in the range where the solvent does not boil, for example, preferably in the range of 60 ° C. or more and 80 ° C. to 110 ° C. The pressure is determined so that the solvent does not boil at the set temperature.

  In the present invention, the norbornene-based resin solvent includes high-boiling solvents such as toluene, xylene, ethylbenzene, chlorobenzene, trimethylbenzene, diethylbenzene, and isopropylbenzene, and among these, toluene, xylene, and chlorobenzene are preferable. Alternatively, a mixed solvent of these high-boiling solvents and low-boiling solvents such as cyclohexane, benzene, tetrahydrofuran, hexane, and octane may be used.

  Further, as the solvent for the norbornene resin, methylene chloride may be used alone or mixed with the above solvent.

  For example, after the cellulose ester or norbornene resin is dissolved in a pressurized container, the solution is taken out from the container while cooling, or extracted from the container with a pump or the like, cooled with a heat exchanger or the like, and used for film formation. .

  The type of the pressure vessel 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 in the range of not less than the boiling point of the solvent used and in the range where the solvent does not boil, for example, preferably in the range of 60 ° C. or more and 80 ° C. 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 lower by 5 ° C. to 10 ° C. than the boiling point, and performing casting at that temperature is more preferable because the dope viscosity can be reduced.

  In the present invention, fine particles are added as a matting agent to the cellulose ester or norbornene resin film. Here, the kind of fine particles may be an inorganic compound or an organic compound, and examples of the inorganic compound include fine particles such as silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, and tin oxide. 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 such 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 preferred in terms of controlling dispersibility and particle size.

  In the present invention, the addition amount of the fine particles is 0.05 to 0.5% by weight added to the film. Preferably, it is 0.10 wt%-0.35 wt%, more preferably 0.20 wt%-0.30 wt%.

  In the method of the present invention, the fine particles are dispersed by treating the composition in which the fine particles and the solvent are mixed with a high-pressure dispersing apparatus. 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 narrow tube.

It is preferable that the maximum pressure condition inside the apparatus is 100 kgf / cm ² or more in a thin tube having a tube diameter of 1 μm 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 device includes an ultra-high pressure homogenizer (trade name: Microfluidizer) manufactured by Microfluidics Corporation or a nanomizer manufactured by Nanomizer. Homogenizers and the like.

  For example, fine particles are dispersed in a solvent containing 25 wt% to 100 wt% of a water-soluble solvent, and then the fine particle dispersion is mixed with a water-insoluble organic solvent 0.5 to 1.5 times as much as the water-soluble solvent. Add and dilute. Next, this fine particle dispersion is mixed with a resin solution obtained by dissolving cellulose ester or norbornene resin in a solvent.

  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.

  Further, the water-insoluble solvent is not particularly limited, but it is preferable to use a solvent used when forming a cellulose ester or norbornene-based resin, a solvent having a solubility in water of 30% by weight or less, methylene chloride, Examples include chloroform and methyl acetate.

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

  In the present invention, a dope obtained by dissolving a cellulose ester or a norbornene resin is cast on a support (casting process), and then heated to remove a part of the solvent (drying process on the support). Then, the film peeled off from the support is dried (film drying step) to obtain a cellulose ester or norbornene resin film.

  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 better cast on a support at 5 ° C. to 30 ° C. In order to increase the peeling limit time, it is preferable to cast on a support at 5 to 15 ° C. 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 40 ° C. to 70 ° C. within 30% from the casting. By doing so, evaporation of the solvent is promoted, and it can be peeled off from the support as soon as possible, and the peel strength is further increased. The dope temperature is more preferably set to 55 ° C. to 70 ° C. within 30%. This temperature is preferably maintained at 20% or more, more preferably 40% or more.

  Drying on the support is preferably peeled from the support with a residual solvent amount of 60% to 150% because the peel strength from the support is reduced, and more preferably 80% to 120%. The dope temperature at the time of peeling is preferably 0 ° C. to 30 ° C., because the base strength at the time of peeling can be increased and the base breakage at the time of peeling can be prevented, and 5 ° C. to 20 ° C. is more preferable.

  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 peeled 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 good film. 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 peeling 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. Shrinkage increases with drying at higher temperatures. In order to improve the flatness of the finished film, it is preferable to dry while suppressing the shrinkage as much as possible. From this point, for example, a method / tenter method in which all or part of the drying process as shown in JP-A-62-46625 is performed while holding the width at both ends of the web with a clip in the width direction. 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 in the range of 40 ° C. to 150 ° C. and divided into 3 to 5 stages, and it is preferable to increase the temperature step by step, more preferably in the range of 80 ° C. 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. In the case of an air atmosphere, it goes without saying that the dry atmosphere is carried out in consideration of the explosion limit concentration of the solvent.

  In the method of the present invention, the winder used in the step of winding the cellulose ester or norbornene-based resin film may be a commonly used one, such as a constant tension method, a constant torque method, a taper tension method, an internal stress. It can be wound by a winding method such as a constant program tension control method.

  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 or norbornene-based resin film to make the end portions bulky.

Ratio X (%) of knurling height (a: μm) to film thickness (d: μm)
Ratio X (%) = (a / d) × 100
In this case, the range of X = 0 to 25% is good for stabilizing the winding property. Preferably, it is 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 is deteriorated, which is not preferable.

  In the present invention, the thickness of the cellulose ester or norbornene-based resin film is generally 20 μm to 200 μm. However, the thickness and weight of the polarizing plate used in the LCD is required to be 20 μm. It is preferably ˜65 μm, more preferably 30 μm to 60 μm, and still more preferably 35 μm to 50 μm. 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 preparation process, and if it is thicker than this, it will contribute to the thinning of the LCD Few.

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

Examples 1-8
[Preparation of fine particle dispersion (a-1)]
Ethanol 27 parts by weight Fine particles I / Silicon dioxide fine particles 3 parts by weight (Product name: AEROSIL-R972V, primary particle size: 16 nm)
The above materials were mixed in a predetermined container, stirred for 30 minutes at 500 rpm, dispersed in a Manton Gorin type high pressure disperser at a pressure of 250 kgf / cm ² , and then the dispersion was dissolved in methylene chloride 27. The fine particle dispersion (a-1) was prepared by diluting with parts by weight.

[Preparation of cellulose triacetate solution (b-1)]
Cellulose triacetate synthesized from cotton linter
(Degree of acetylation 61.0%) 85 parts by weight Cellulose triacetate synthesized from wood pulp
(Degree of acetylation 61.0%) 15 parts by weight Ethyl phthalyl ethyl glycolate (plasticizer A) 2 parts by weight Triphenyl phosphate (plasticizer B) 8 parts by weight Methylene chloride (boiling point: 39.8 ° C.) 475 parts by weight Ethanol 50 parts by weight Referring to FIG. 1, the above materials are put into a dissolution vessel (1), heated to 70 ° C., and stirred to completely dissolve cellulose triacetate (TAC). ) The time required for dissolution was 4 hours. The cellulose triacetate solution (b-1) is then discharged from the flow pipe (2) connected to the bottom of the dissolution vessel (1), transferred by the operation of the liquid feed pump (3), and filtered (4) In Example 1, a filter paper having an absolute filtration accuracy of 0.005 mm was used, and filtration was performed at a filtration flow rate of 300 l / m ² · hr and a filtration pressure of 9.8 × 10 ⁵ Pa.

[Preparation of additive solution (c-1)]
75 parts by weight of cellulose triacetate solution (b-1)
2- (2'-hydroxy-3 ', 5'-di-t-butylphenyl) bezotriazole (UV absorber I) 25 parts by weight Fine particle dispersion (a-1) 60 parts by weight Methylene chloride 290 parts by weight Dissolved Add a part of the filtered cellulose triacetate solution (b-1) while stirring the methylene chloride in the kettle (6), and then add the UV absorber and the fine particle dispersion (a-1) in this order. did. After the addition, the mixture was heated to 40 ° C. and dissolved for 30 minutes to prepare an additive solution (c-1). Next, the additive solution (c-1) is discharged from the flow pipe (7) connected to the bottom of the dissolution vessel (6), transferred by the operation of the liquid feed pump (8), and filtered ( In 9), filtration was performed with a filter having a nominal filtration accuracy of 20 μm.

[Preparation of dope for cellulose triacetate film]
In the filter (4), a filter paper having an absolute filtration accuracy of 0.005 mm is used, the filtration is performed at a filtration flow rate of 300 l / m ² · hour, and a filtration pressure of 1.0 × 10 ⁶ Pa, and the flow through the feed pipe (2). To the main part (remainder) of the cellulose triacetate solution (b-1) after filtration, the additive solution (c-1) after filtration from the flow pipe (7) is added as shown in Table 1. A dope for a cellulose triacetate film was prepared by adding in-line at a ratio such that the amount was sufficient and mixing with a static mixer (10).

[Preparation of cellulose triacetate film sample]
A dope for the above-described cellulose triacetate film is supported on a 30 ° C. support made of a stainless steel endless belt from a casting die (11) at a dope temperature of 35 ° C. using the solution casting film forming apparatus shown in FIG. 12) Casted uniformly on top. After holding for 60 seconds on the support (12) and drying to a peelable range, the web (dope film) was peeled from the support (12). At this time, the residual solvent amount of the web was 25%. The time required from casting the dope to peeling was 3 minutes. While the web peeled from the support (12) is transported by a number of rolls, drying is completed in a drying zone of 50 ° C., 90 ° C., 120 ° C., and 130 ° C. And a cellulose triacetate (TAC) film sample having a film thickness of 40 μm was prepared by winding the cellulose triacetate film in a roll shape around the core.

  The film width was 1300 mm and the winding length was 3000 m. The winding tension was an initial tension of 20 kg / 1300 mm and a final winding tension of 10 kg / 1300 mm.

  In Example 1 and Examples 5 to 8, a pipe having an inner diameter of 200 mm is used as the pipe (5) when part of the cellulose triacetate solution (b-1) is added to the additive solution (c-1). In addition, a stainless steel punch plate (13) (solution flow regulating plate) having four solution flow holes (14) having a diameter of 50 mm was provided at the discharge port of the pipe (5). In Example 2, a pipe having an inner diameter of 100 mm is used as the pipe (5), and a punch plate (13) (solution circulation) having seven solution circulation holes (14) having a diameter of 25 mm at the discharge port of the pipe (5). A restriction plate was provided. In Example 3, a pipe having an inner diameter of 50 mm was used as the pipe (5), but the addition was performed without providing a punch plate at the discharge port of the pipe (5). In Example 4, a pipe having a diameter of 200 mm is used as the pipe (5), and a punch plate (13) (solution) having 16 solution flow holes (14) having a diameter of 25 mm at the discharge port of the pipe (5). Distribution restriction board).

  By the way, although the boiling point of methylene chloride, which is a solvent of cellulose triacetate contained in the cellulose triacetate solution (b-1), is 39.8 ° C., the cellulose triacetate solution (c-1) when added to the additive solution (c-1) ( As shown in Table 1 below, the temperature of b-1) was 39 ° C. in Examples 1 to 4 and Examples 7 and 8. Moreover, in Example 5, this temperature was 35 degreeC, and in Example 6, it was 30 degreeC, and all were made into the range of the boiling point --10 degreeC of a methylene chloride.

Comparative Examples 1-3
For comparison, a cellulose triacetate film was produced in the same manner as in Example 1 above. However, as a pipe for adding the cellulose triacetate solution (b-1) to the additive solution (c-1), a comparative example was used. In Example 1, a pipe having an inner diameter of 250 mm outside the scope of the present invention was used, and in Comparative Examples 2 and 3, a pipe having an inner diameter of 400 mm outside the scope of the present invention was used. Moreover, in these Comparative Examples 1-3, addition was performed without providing a punch plate in the discharge port of piping. In addition, as shown in the following Table 1, the temperature of the cellulose triacetate solution (b-1) when added to the additive solution (c-1) is outside the scope of the present invention in Comparative Examples 1 and 2. It was set to 25 ° C. Moreover, in the comparative example 3, it was 42 degreeC which is outside the range of this invention.

  Next, with respect to the cellulose triacetate films obtained in Examples 1 to 8 and Comparative Examples 1 to 3, the following evaluations were performed for variations in ultraviolet transmittance, variations in the number of protrusions on the film surface, and spot defects. The results obtained are also shown in Table 1 below.

(Evaluation methods)
Variation in UV transmittance of cellulose triacetate film: Variation in UV transmittance of cellulose triacetate film is measured by measuring the spectrum of the cellulose triacetate film sample using, for example, a spectrophotometer (Spectrophotometer U-3200 manufactured by Hitachi, Ltd.). In order to obtain the transmittance at 380 nm, the cellulose triacetate film wound up in a roll shape is unwound, and sampled at an interval of 100 mm in an area of 5 m long × 1 m wide, for example, the maximum value with respect to the average value And the variation of the minimum value was calculated as a ratio.

Variation in the number of protrusions on the surface of the cellulose triacetate film: The variation in the number of protrusions on the surface of the cellulose triacetate film is, for example, a metal support of the formed cellulose triacetate film sample using a three-dimensional surface structure analysis microscope (New View 5010 manufactured by ZYGO). The surface roughness Ra of the surface opposite to the body (12) is measured, and the number of protrusions having a height that is at least three times the surface roughness Ra measured by the attached analysis software is calculated. The number of protrusions per 1 mm ² Was calculated. The wound cellulose triacetate film was unwound and sampled and measured at an interval of 100 mm, for example, with an area of 5 m length x 1 m width, and the variation between the maximum value and the minimum value was calculated as a ratio with respect to the average value.

Spot defect: Using a laser scanning fault meter, the fluctuation of the amount of light transmitted through the cellulose triacetate film was converted into voltage, and spot failures of 100 μm or more were counted, and the number of each 100 m was calculated. The average value at 2600 m was defined as the number of spot failures. If it is 3 pieces / 100 m or less, it is a level with no practical problem.

  As is clear from the results in Table 1 above, according to the cellulose triacetate films of Examples 1 to 8 according to the present invention, both the variation in ultraviolet transmittance and the variation in the number of protrusions on the film surface are small, and spot defects are Therefore, even when the film thickness of the cellulose triacetate film used as a protective film for polarizing plate was reduced to 40 μm, a cellulose triacetate film having excellent performance and no spot defects could be obtained. Thus, according to the present invention, the cellulose triacetate solution (b-1) mainly composed of cellulose triacetate is filtered, and a part of the filtered cellulose triacetate solution (b-1) is converted into an ultraviolet absorber and fine particles. Since the additive solution (c-1) is prepared by mixing with additives such as the above and a solvent, the solubility of the resin to be added can be increased, and the mixing state of the fine particles and the UV absorber can be improved. With the diversification of liquid crystal display devices, it is possible to maintain uniformity of various additives in the transparent cellulose triacetate film to be used, reduce variations in optical properties and slippage, and reduce image defects. It is possible to eliminate spot defects that can be.

  On the other hand, according to the cellulose triacetate films of Comparative Examples 1 to 3, in any case, the variation in ultraviolet transmittance and the variation in the number of protrusions on the film surface were larger than those in Examples 1 to 8 of the present invention. In addition, the number of spot defects was very large, and the film was not suitable for use as a thinned polarizing plate protective film.

Examples 9-16
A norbornene resin film was prepared in substantially the same manner as in Examples 1 to 8, except that a norbornene resin was used instead of cellulose triacetate as the transparent resin.

[Preparation of fine particle dispersion (a-2)]
Ethanol 27 parts by weight Fine particles I / Silicon dioxide fine particles 3 parts by weight (Product name: AEROSIL-R972V, primary particle size: 16 nm)
The above materials were mixed in a predetermined container, stirred for 30 minutes at 500 rpm, dispersed in a Manton Gorin type high pressure disperser at a pressure of 250 kgf / cm ² , and then the dispersion was dissolved in methylene chloride 27. The fine particle dispersion (a-2) was prepared by diluting with parts by weight.

[Preparation of norbornene resin solution (b-2)]
Norbornene resin (Arton G JSR) 80 parts by weight Ethylphthalyl ethyl glycolate (plasticizer A) 2 parts by weight Triphenyl phosphate (plasticizer B) 8 parts by weight Methylene chloride (boiling point: 39.8 ° C.) 250 parts by weight Ethanol 10 parts by weight Referring to FIG. 1, the above materials are put into a melting pot (1), heated to 70 ° C., and stirred to completely dissolve the norbornene resin, and the norbornene resin solution (b-2) Got. The time required for dissolution was 4 hours. The norbornene resin solution (b-2) is then discharged from the flow pipe (2) connected to the bottom of the dissolution vessel (1), transferred by the operation of the liquid feed pump (3), and filtered (4 ), A filter paper having an absolute filtration accuracy of 0.005 mm was used, and filtration was performed at a filtration flow rate of 300 l / m ² · hr and a filtration pressure of 1.0 × 10 ⁶ Pa.

[Preparation of additive solution (c-2)]
75 parts by weight of norbornene resin solution (b-2)
2- (2′-hydroxy-3 ′, 5′-di-t-butylphenyl) bezotriazole (UV absorber I) 25 parts by weight Fine particle dispersion (a-2) 60 parts by weight Methylene chloride 290 parts by weight Dissolved In the kettle (6), a part of the norbornene-based resin solution (b-2) after filtration was added while stirring the methylene chloride, and then the ultraviolet absorber and the fine particle dispersion (a-2) were added in this order. Added. After the addition, the mixture was heated to 40 ° C. and dissolved for 30 minutes to prepare an additive solution (c-2). Next, this additive solution (c-2) is discharged from the flow pipe (7) connected to the bottom of the dissolution vessel (6), transferred by the operation of the liquid feed pump (8), and filtered ( In 9), filtration was performed with a filter having a nominal filtration accuracy of 20 μm.

[Preparation of dope for norbornene resin film]
In the filter (4), a filter paper having an absolute filtration accuracy of 0.005 mm is used, the filtration is performed at a filtration flow rate of 300 l / m ² · hour, and a filtration pressure of 1.0 × 10 ⁶ Pa, and the flow through the feed pipe (2). In the main part (remaining part) of the norbornene-based resin solution (b-2) after filtration, the additive solution (c-2) after filtration from the flow pipe (7) is used, and the fine particles are as shown in Table 2. A dope for a norbornene-based resin film was prepared by adding in-line at a ratio such that the amount would be added and mixing with a static mixer (10).

[Preparation of norbornene-based resin film sample]
A dope for the norbornene-based resin film is supported by a 30 ° C. support made of a stainless steel endless belt from a casting die (11) at a dope temperature of 35 ° C. using the solution casting film forming apparatus shown in FIG. (12) Uniformly cast on top. After holding for 60 seconds on the support (12) and drying to a peelable range, the web (dope film) was peeled from the support (12). At this time, the residual solvent amount of the web was 25%. The time required from casting the dope to peeling was 3 minutes. While the web peeled from the support (12) is transported by a number of rolls, drying is completed in a drying zone of 50 ° C., 90 ° C., 120 ° C., and 130 ° C. And a norbornene resin film sample having a film thickness of 40 μm was produced by winding the norbornene resin film in a roll shape around the core.

  The film width was 1300 mm and the winding length was 3000 m. The winding tension was an initial tension of 20 kg / 1300 mm and a final winding tension of 10 kg / 1300 mm.

  In Example 9 and Examples 13 to 16, a pipe having an inner diameter of 200 mm is used as the pipe (5) when a part of the norbornene resin solution (b-2) is added to the additive solution (c-2). In addition, a stainless steel punch plate (13) (solution flow regulating plate) having four solution flow holes (14) having a diameter of 50 mm was provided at the discharge port of the pipe (5). In Example 10, as a pipe (5), a pipe having an inner diameter of 100 mm is used, and a punch plate (13) having seven solution flow holes (14) having a diameter of 25 mm at the discharge port of the pipe (5) (solution flow A restriction plate was provided. In Example 11, a pipe having an inner diameter of 50 mm was used as the pipe (5), but the addition was performed without providing a punch plate at the discharge port of the pipe (5). In Example 12, a pipe having an inner diameter of 200 mm is used as the pipe (5), and a punch plate (13) (solution) having 16 solution flow holes (14) having a diameter of 25 mm at the discharge port of the pipe (5). A distribution regulating plate) was provided and added.

  By the way, although the boiling point of methylene chloride, which is the solvent of the norbornene resin contained in the norbornene resin solution (b-2), is 39.8 ° C., the norbornene system when added to the additive solution (c-2). As shown in Table 2 below, the temperature of the resin solution (b-2) was 39 ° C. in Examples 9 to 12 and Examples 15 and 16. In Example 13, this temperature was 35 ° C., and in Example 6, it was 30 ° C., and both were within the range of the boiling point of methylene chloride to −10 ° C.

Comparative Examples 4-6
For comparison, a norbornene-based resin film is produced in the same manner as in Example 9, but as a pipe for adding the norbornene-based resin solution (b-2) to the additive solution (c-2), In Comparative Example 4, a pipe having an inner diameter of 250 mm outside the range of the present invention was used, and in Comparative Examples 5 and 6, a pipe having an inner diameter of 400 mm that was outside the range of the present invention was used. Moreover, in these Comparative Examples 4-6, addition was performed without providing a punch plate in the discharge port of piping. Further, the temperature of the norbornene-based resin solution (b-2) when added to the additive solution (c-2) is outside the scope of the present invention in Comparative Examples 4 and 5, as shown in Table 2 below. The temperature was 25 ° C. Moreover, in the comparative example 6, it was 42 degreeC which is outside the range of this invention.

  Next, for the norbornene-based resin films obtained in Examples 9 to 16 and Comparative Examples 4 to 6, the following evaluations were made for variations in ultraviolet transmittance, variations in the number of protrusions on the film surface, and spot defects. The results obtained are shown in Table 2 below.

(Evaluation methods)
Variation in UV transmittance of norbornene-based resin film: Variation in UV transmittance of norbornene-based resin film is measured using, for example, a spectrophotometer (Spectrophotometer U-3200 manufactured by Hitachi, Ltd.). Is measured to obtain the transmittance at 380 nm, and the norbornene-based resin film wound up in a roll shape is unwound, for example, sampled at 100 mm intervals in an area of 5 m length × 1 m width, The variation between the maximum value and the minimum value was calculated as a ratio.

Variation in the number of protrusions on the surface of the norbornene-based resin film: The variation in the number of protrusions on the surface of the norbornene-based resin film is, for example, a norbornene-based resin film sample formed using a three-dimensional surface structure analysis microscope (New View 5010 manufactured by ZYGO). The surface roughness Ra of the surface opposite to the metal support (12) is measured, and the number of protrusions with a height of 3 times or more of the surface roughness Ra measured by the attached analysis software is calculated per 1 mm ² The number of protrusions was calculated. The wound norbornene-based resin film was unwound, sampled and measured at an interval of 100 mm, for example, with an area of length 5 m × width 1 m, and the variation between the maximum value and the minimum value was calculated as a ratio with respect to the average value.

Spot defect: Using a laser scanning type fault meter, the fluctuation of the transmitted light amount of the norbornene-based resin film was converted into a voltage, spot failures of 100 μm or more were counted, and the number for every 100 m was calculated. The average value at 2600 m was defined as the number of spot failures. If it is 3 pieces / 100 m or less, it is a level with no practical problem.

  As is clear from the results of Table 2 above, according to the norbornene resin films of Examples 9 to 16 according to the present invention, both the variation in the ultraviolet transmittance and the variation in the number of protrusions on the film surface are small, and the spot defect Therefore, even when the film thickness of the norbornene resin film used as the retardation compensation film is reduced to 40 μm, for example, a norbornene resin film having excellent performance and no spot defects could be obtained.

  As described above, according to the present invention, the norbornene-based resin solution (b-2) containing the norbornene-based resin as a main component is filtered, and a part of the norbornene-based resin solution (b-2) after the filtration is absorbed by ultraviolet rays. Since the additive solution (c-2) is prepared by mixing with additives such as additives and fine particles and solvent, the solubility of the resin to be added can be increased, and the mixed state of fine particles and ultraviolet absorbers With the diversification of liquid crystal display devices, the uniformity of various additives in the transparent norbornene resin film to be used is reduced, and variations in optical characteristics and slipperiness are reduced. At the same time, spot defects that can be image defects can be eliminated.

  On the other hand, according to the norbornene-based resin films of Comparative Examples 4 to 6, in any case, as compared with Examples 9 to 16 of the present invention, there was a variation in ultraviolet transmittance and a variation in the number of protrusions on the film surface. It was large and had many spot defects and was not suitable for use as a thin film retardation compensation film.

It is a perspective view which shows the apparatus which enforces the method to manufacture the cellulose-ester film of this invention. It is a principal part expansion notched perspective view of the piping which flows in a part of resin solution in the film manufacturing apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1: Melting pot 2: Flow pipe 3: Liquid feed pump 4: Filter 5: Branch flow pipe 6: Dissolving pot 8: Liquid feed pump 9: Filter 10: Static mixer 11: Casting die 12: Support body 13: Solution inflow restricting plate 14: Solution flow hole

Claims (6)

  A method for producing a transparent resin film of a cellulose ester or norbornene resin by a solution casting film forming method, wherein a resin solution comprising a resin comprising a cellulose ester or norbornene resin as a main component is converted from a cellulose ester or norbornene resin. In-line addition of an additive solution containing a resin, an ultraviolet absorber, and fine particles to prepare a dope for the transparent resin film, a resin solution mainly composed of a resin composed of the cellulose ester or norbornene resin is used. A portion of the resin solution after filtration is mixed with an additive such as a UV absorber and fine particles and a solvent to prepare an additive solution, and the additive solution is made of the cellulose ester or norbornene resin. Add to the main part of resin solution containing resin as a main component The Rukoto, to prepare a dope of the transparent resin film, characterized by producing a transparent resin film by a solution casting film forming method using this dope method for producing a transparent resin film.   A pipe that flows in to filter a resin solution mainly composed of a cellulose ester or norbornene-based resin and mix a part of the filtered resin solution with an additive such as an ultraviolet absorber and fine particles and a solvent. The method for producing a transparent resin film according to claim 1, wherein the pipe has an inner diameter of 200 mm or less.   Filter a resin solution mainly composed of a cellulose ester or norbornene resin, and add a part of the filtered resin solution to an ultraviolet absorber, fine particles and other additives and a solvent. The method for producing a transparent resin film according to claim 1 or 2, wherein a solution inflow regulating plate having at least two solution circulation holes having a diameter of 50 mm or less is provided at the discharge port. The boiling point of a solvent contained in a resin solution mainly composed of a cellulose ester or norbornene resin is A ° C., and a part of the resin solution is mixed with an additive such as an ultraviolet absorber and fine particles and a solvent after filtration. When the temperature at the time of B
A-10 ≦ B ≦ A
The manufacturing method of the transparent resin film as described in any one of Claims 1-3 characterized by the above.   It is a transparent resin film manufactured with the manufacturing method of the transparent resin film as described in any one of the said Claims 1-4, Comprising: The ultraviolet-ray transmittance per unit film thickness in 380 nm is a width direction at an interval of 100 mm The transparent resin film is characterized in that the dispersion of the value of the ultraviolet transmittance when measured in the longitudinal direction is within ± 5% of the average value.   It is a transparent resin film manufactured by the manufacturing method of the transparent resin film as described in any one of the said Claims 1-4, Comprising: Surface roughness of the film surface side opposite to the support body for casting at the time of film forming The variation in the number of protrusions when measuring the number of protrusions having a height of 3 times or more per unit area in the width direction and the longitudinal direction at intervals of 100 mm is ± 15% of the average value A transparent resin film characterized by being within.

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