JP2004107498A - Method for preparing dope and method for forming film by solution casting - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for preparing a dope for forming a cellulose acylate film suitable for applications such as a protection film especially for a polarizing plate of a liquid crystal display device, an optical compensation film, a color film and a photosensitive material; and to provide a method for forming the film by solution casting. <P>SOLUTION: The method for preparing the dope comprises carrying out the preparation by an apparatus having a concentrating device 35 for concentrating the dope, and an inline mixer 41 for adding fine particles to the dope, installed in a dope-preparing line 10 for preparing the dope obtained by dissolving a polymer in a solvent and regulated so that the inline mixer 41 is arranged after the concentrating device 35. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a dope preparation method and a solution film forming method, and in particular, a cellulose acylate film suitable for applications such as a protective film for a polarizing plate of a liquid crystal display device, an optical compensation film, a color film, or a photographic material is formed. The present invention relates to a dope preparation method and a solution film forming method to which the dope preparation method is applied.
[0002]
2. Description of the Related Art A film formed from cellulose acylate, particularly cellulose triacetate having an average degree of acetylation of 57.5 to 62.5% (hereinafter referred to as TAC film) has its toughness and flame retardancy. Is used as a film base for photographic photosensitive materials. In addition, since the TAC film is excellent in optical isotropy, it is suitable for use as a protective film for a polarizing plate, an optical compensation film, and a color film of a liquid crystal display device whose market is expanding in recent years.
[0003]
A cellulose acylate film is generally produced by a solution casting method, and can produce a film having excellent optical properties and physical properties as compared with other production methods such as a melt casting method. In the solution casting method, a dope is prepared by dissolving a polymer in a solvent (mainly an organic solvent), and then the dope is cast on a casting support such as a casting band or a casting drum to form a dope. It is.
[0004]
In film formation of a cellulose acylate film by such a solution film forming method, for the purpose of imparting slipperiness of the cellulose acylate film, it is mainstream to add fine particles such as silicon dioxide, titanium dioxide, calcium carbonate to the dope. It has become. For example, Patent Document 1 discloses a cellulose ester film containing 0.04 to 0.3 wt% of fine particles. Patent Document 2 discloses that a method for producing a cellulose triacetate film having excellent light transmittance and improved slipperiness is composed of cellulose triacetate and fine particles having a methyl group on the surface dispersed in the cellulose triacetate. Yes.
[0005]
[Patent Document 1]
Japanese Patent Laid-Open No. 2001-114907
[Patent Document 2]
Japanese Patent Laid-Open No. 7-11055
[Problems to be solved by the invention]
However, the addition of fine particles into the dope is effective in improving the slipperiness of the cellulose acylate film, while the fine particles added into the dope may agglomerate to a size of several tens of μm or more. If it is contained in the film as it is, there is a problem that the light transmittance of the film is lowered or the light is blocked, thereby causing a display defect in a display using the film. Further, when the fine particles are aggregated, it is easy to block the filter medium when filtering the foreign material of the dope at the dope preparation stage, and the filtration life is shortened, so that there is a problem that the filtration efficiency is lowered. Therefore, it is an important subject at what timing the fine particles are added in the dope preparation line so as not to cause such a problem.
[0008]
The present invention has been made in view of such circumstances, and can effectively suppress the aggregation of fine particles added to the dope. Therefore, the filtration of the dope is alleviated, and the dope is reduced. It aims at providing the dope preparation method and solution casting method which can improve the quality of the film manufactured by casting.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a dope preparation comprising a concentration step for concentrating the dope and an addition step for adding fine particles into the dope in a dope preparation line for preparing a dope in which a polymer is dissolved in a solvent. It is a method, Comprising: The said addition process is arrange | positioned after the said concentration process.
[0010]
While the present invention can reduce the drying load of the solvent after casting the dope by concentrating the dope and increasing the polymer concentration in the dope, it is said that one of the major factors for the aggregation of fine particles is the concentration of the dope According to the present invention, since the fine particle addition step is arranged after the dope concentration step, aggregation of the fine particles added to the dope can be effectively suppressed.
[0011]
According to a second aspect of the present invention, in the first aspect, the dope is a cellulose acylate solution in which cellulose acylate is dissolved in a solvent. This is because, among various dopes, cellulose acylate solutions used for applications such as protective films for polarizing plates of liquid crystal display devices, optical compensation films, color films, or photographic photosensitive materials are particularly slippery due to the addition of fine particles. Improvement is required. Therefore, by using the present invention, it is possible to prepare a dope that effectively suppresses aggregation of fine particles, so that the light transmittance of the film formed by casting the dope is reduced or light is blocked. There is nothing to do. Therefore, a high quality film can be manufactured.
[0012]
A third aspect of the present invention is characterized in that, in the first or second aspect, the dope preparation line includes a filtration step, and an addition step is arranged after the concentration step and the filtration step. The dope preparation line preferably includes a filtration step for removing foreign matters in the dope, but if the addition step of the fine particles is arranged before the filtration step, only a part of the fine particles are trapped in the filtration step and the filter medium is blocked. Instead, the designed amount of fine particles is not contained in the film. Therefore, when the dope preparation line includes a concentration step, a filtration step, and a fine particle addition step, the fine particle addition step is preferably arranged after the concentration step and the filtration step.
[0013]
Moreover, although it is the positional relationship of the concentration process and filtration process in a dope preparation line, if dope is filtered after the dope is concentrated in the concentration process, the dope with a high concentration is filtered, and thus the filtration load increases. Therefore, it is preferable to arrange the filtration device for removing foreign substances in the dope before the concentration step (upstream of the dope preparation line). However, since an insoluble film of the polymer may be formed with the concentration of the dope, it is preferable to arrange a filtration step after the concentration of the dope. From this, in order from the upstream side of the dope preparation line, the filtration step that mainly removes foreign matters in the dope → the concentration step of the dope → the filtration step that mainly removes the insoluble film of the polymer accompanying the concentration → the addition step of the fine particles It is preferable to arrange. By arranging in this way, if foreign matter in the dope is filtered with a dope having a concentration lower than the dope concentration at the time of casting, and then the dope is concentrated to a concentration suitable for casting, The filtration load in the filtration step of filtering foreign matter can be reduced, and the filtration life can be extended.
[0014]
A fourth aspect of the present invention is the method according to any one of the first to third aspects, in which the dispersion liquid in which the fine particles are dispersed in the same solvent as the solvent for dissolving the polymer or a solution composed of the same solvent is added in the addition step. It is characterized by doing. Thereby, since the fine particles are easily dispersed uniformly in the dope, the fine particles are less likely to aggregate.
[0015]
According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the solvent is a non-chlorine organic solvent as a main solvent. Here, the main solvent refers to a solvent having the highest constituent ratio in the case of a mixed solvent.
[0016]
A sixth aspect of the present invention is characterized in that the dope prepared by the dope preparing method according to any one of the first to fifth aspects is cast on a casting support to form a film. By forming a solution casting method to which the dope preparation method according to any one of claims 1 to 5 is applied, a film is not produced by casting a dope in which fine particles are aggregated. Can be manufactured.
[0017]
A seventh aspect of the present invention is characterized in that in any one of the first to sixth aspects, the dope is formed by a co-casting method. Thereby, a filter medium can be changed according to the removal degree of the foreign material calculated | required by the polymer solution for every co-casting. For example, a dope that forms a film by co-casting three layers and forms a surface layer uses a filter medium that performs high-precision filtration, and a dope that forms an intermediate layer uses a filter medium that performs relatively low-precision filtration. If the film is used, the filtration load can be reduced as compared with the case where the film is formed by single casting of one layer and all dopes are filtered with high accuracy. Thereby, the filtration life can be lengthened.
[0018]
Claim 8 of the present invention is a film formed by the solution casting method of claim 6 or 7, and claim 9 is a polarizing plate protective film manufactured using the film of claim 8. Reference numeral 10 denotes a polarizing plate manufactured using the polarizing plate protective film of claim 9, and claim 11 is a liquid crystal display device manufactured using the polarizing plate of claim 10.
[0019]
A twelfth aspect is an optical compensation film manufactured using the film of the eighth aspect, and a thirteenth aspect is a liquid crystal display device manufactured using the optical compensation film of the twelfth aspect.
[0020]
A fourteenth aspect of the present invention is a photographic photosensitive material produced using the film of the eighth aspect.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of a dope preparation method and a solution casting method according to the present invention will be described in detail with reference to the accompanying drawings.
[0022]
FIG. 1 shows a dope preparation line 10 to which the dope preparation method according to the present invention is applied, and FIG. 4 shows a film formation line 50 for forming a dope prepared in the dope preparation line 10 into a film.
[0023]
The dope preparation line 10 sends a necessary amount of solvent from the solvent tank 11 to the dissolution tank 12. The solvent tank 11 is filled with a solvent (even when a mixed solvent is used, in the following description, it may be simply referred to as a solvent). This solvent is fed while adjusting the liquid feeding amount by a solvent tank opening / closing valve 13 attached between the solvent tank 11 and the dissolution tank 12.
[0024]
Next, the polymer charged in the meter 14 is fed into the dissolution tank 12 while being metered. In addition, although it is preferable to use TAC for a polymer, it is not limited to this.
[0025]
Further, the plasticizer is sent from the plasticizer tank 15 to the dissolution tank 12. A plasticizer tank opening / closing valve 16 is attached between the plasticizer tank 15 and the dissolution tank 12, and a necessary amount of plasticizer is fed into the dissolution tank 12. In addition, although it is preferable to use a triphenyl phosphate as a plasticizer, it is not limited to this. In FIG. 1, the plasticizer is fed into the dissolution tank 12 as a solution in which the plasticizer is dissolved in a solvent, but the present invention is not limited to this method. When the plasticizer is liquid at normal temperature, it can be fed into the dissolution tank 12 in the liquid state. Further, when the plasticizer is solid, it can be fed into the dissolution tank 12 using a measuring instrument. In the present invention, the amount of the plasticizer fed to the dissolution tank 12 is 5 to 20% by weight with respect to the polymer described above, and the plasticity of the film formed from the prepared dope is most preferable as a product. A flexible one is obtained. However, the amount of the plasticizer fed into the dissolution tank 12 in the present invention is not limited to the above-described range.
[0026]
In the above description, the order of charging into the dissolution tank 12 is the order of solvent, polymer, and plasticizer, but the present invention is not necessarily limited to this order. For example, after a polymer is weighed and sent to the dissolution tank 12, a preferred amount of solvent can be sent. Further, the plasticizer does not necessarily have to be sent to the dissolution tank 12 in advance, and can be mixed into a mixture of a polymer and a solvent in a later step.
[0027]
The dissolution tank 12 is provided with a stirring blade 18 that is rotated by a motor (not shown). As the stirring blade 18 rotates, the solvent, polymer, and plasticizer that has been fed into the dissolution tank 12 as needed are agitated to roughly dissolve solutes such as polymer in the solvent. The rough dissolution means a state where the solute is not completely dissolved in the solvent. In the present invention, the stirring time in the dissolution tank 12 by the stirring blade 18 is preferably 30 to 90 minutes, but is not limited to this range.
[0028]
Next, it is preferable from the viewpoint of cost that the dope is once sent into the storage tank 20, the inside of the dissolution tank 12 is emptied, and the process of forming a dope in a coarse dissolution state is repeated. The storage tank 20 is also provided with a stirring blade 22 that is rotated by a motor (not shown), and stirs the supplied dope to make it uniform. The dope in the storage tank 20 is sent to the first filtration device 30 </ b> A by the pump 23.
[0029]
In the first filtration device 30A, rough filtration is mainly performed to remove foreign substances having a relatively large diameter in the size distribution of foreign substances in the dope. Some polymers in the dope used in the solution casting method use natural materials as raw materials, and the raw materials contain a small amount of materials that do not dissolve in the organic solvent of the dope or are difficult to dissolve There is. In addition, the dope may contain impurities contained in the polymer and other raw materials, and foreign matters such as dust and dust mixed in the raw material transport process and dissolution process. In the present invention, an undissolved polymer in which the polymer is not dissolved in the solvent, a polymer that is solated in the dope, impurities in the raw material, and those that do not dissolve in the solvent such as the foreign matter are all called foreign matters. The dope containing these foreign substances is removed by filtration before the dope is prepared and cast, thereby preventing defects in the formed film.
[0030]
As the first filtration device 30A, a multi-filter method whose main part sectional view is shown in FIG. 2 can be suitably used, but is not limited to this, for example, a cylindrical filtration device, a filter press filtration A known type of filtration device such as a device or an auxiliary filtration device can be used. The advantage of the filter device of the multi-filter method is that the filter 40 is formed in a hollow cylindrical shape, and by providing a plurality (three in the figure), the size of the first filter device 30A is not changed. The area where the dope contacts the filter 40 can be increased.
[0031]
The material of the filter 40 used in the first filtration device 30A is a filter 40 made of a hydrophobic filter material such as a synthetic fiber such as Teflon or polypropylene, or a metal fiber such as stainless steel, or a cellulose fiber. It is preferable to use a filter 40 that is chemically or physically hydrophobized on the surface of the filter 40 formed of a hydrophilic filter material. From the inventors' research, the adsorption phenomenon that closes the pores of the filter 40 is caused by hydrogen bonding between the filter 40 and the foreign matter. In order to prevent hydrogen bonding, the filter 40 has a contact angle with water. This is because it preferably has a hydrophobicity of 40 ° or more. In this case, the filter 40 preferably has a contact angle with water of 70 ° or more, and particularly preferably has a contact angle with water of 90 ° or more. In addition, about the material of the filter 40, the hydrophobic filter 40 can be used suitably similarly with the 2nd-3rd filtration apparatus 30B-30C mentioned later.
[0032]
Next, the dope is fed from the first filtration device 30 </ b> A to the heater 25. A dope in which a solute such as a polymer necessary for film formation is dissolved can be prepared by heating the dope in a roughly dissolved state with the heater 25. The heating time is preferably 5 to 30 minutes and the heating temperature is preferably 60 to 120 ° C, but is not limited to these ranges. If it is less than 5 minutes, the dope may not be completely prepared, and even if it is heated for more than 30 minutes, the necessary solute components are completely dissolved in the solvent, which is a waste of time. At the same time, the prepared dope may be altered. Further, if the heating temperature is less than 50 ° C., the dope may not be completely prepared, and if it exceeds 120 ° C., necessary solute components may be modified. As the heater 25, in order to efficiently prepare the dope, a multi-tube heat exchanger (shell & tube method) or a static mixing stirrer (also referred to as a static mixer) having a heating means with two or more tubes is provided. It is preferable to use an in-line mixer such as) in order to shorten the dope preparation time. In particular, it is more preferable to use a spiral heat exchanger from the viewpoint of heat exchange efficiency. The spiral heat exchanger is composed of two flow paths by winding two plates in a spiral shape from the center. Since this structure can take a wide heat transfer area with respect to the cross-sectional area of the flow path of the process liquid, it is an apparatus having extremely excellent heat exchange efficiency. Moreover, it is preferable to use a material having high corrosion resistance as the material of the heater 25, and more specifically, it is more preferable to use a material formed from stainless steel, titanium, Hastelloy (trade name) or the like. Thereby, it is possible to increase the speed for mass production of the dope without changing the capacity of the dissolution tank 12. Further, when the dope is fed to the heater 25, the pipe is preferably kept warm or heated. When the dope is fed through the pipe, it is also heated, so that dissolution of a solute such as a polymer not dissolved in the solvent in the dope proceeds.
[0033]
Next, the dope heated by the heater 25 is sent to the cooler 26, where it is cooled to below the boiling point of the main solvent constituting the dope to prepare a dope for forming a film of good quality. This is preferable. In the present invention, the method for preparing the dope is not necessarily performed by the heater 25 described above. For example, it is possible in some cases that the dope can be prepared simply by heating the pipe and feeding the dope. Alternatively, in some cases, it is possible to prepare the dope by rapidly rotating the stirring blade 22 in the storage tank 20. The method for preparing the dope as described above is not necessarily limited to the heating method using the heater 25 described above.
[0034]
Next, the dope is sent to the second filtration device 30 </ b> B by the pump 27. The second filtration device 30B performs microfiltration to remove foreign matters from the medium diameter size to the small diameter size in the size distribution of the foreign matters in the dope. In this case, when the dope is concentrated by the concentrating device 35 described later, the filtration load increases. Therefore, most of the foreign matters in the dope are removed by the filtering devices 30A and 30B arranged on the upstream side of the concentrating device 35. It is preferable. Two second filtration devices 30B are arranged in parallel, and are fed to the selected second filtration device 30B via the switch 29.
[0035]
The dope filtered by the second filtration device 30B in the second stage is temporarily stored in the intermediate tank 31, and then sent to the heater 34 by the pump 32 to be heated. The heating time is preferably 5 to 30 minutes and the heating temperature is preferably 60 to 120 ° C, but is not limited to these ranges. The dope heated by the heater 34 is sent to a concentration device 35 to concentrate the dope. In the concentration apparatus 35, it is preferable to concentrate so that the polymer in the dope is in the range of 15% by weight to 20% by weight with respect to the solvent. As the concentrating device 35, a flash type evaporation device that evaporates the solvent by injecting the dope into a decompressed concentrating can can be suitably used, but another concentrating device may be used. The concentrated dope is sent to the cooler 36, cooled to below the boiling point of the main solvent constituting the dope, and temporarily stored in the intermediate tank 37. Next, the dope in the intermediate tank 37 is fed to the third filtration device 30C by the pump 38, and mainly the insoluble film of the polymer that may be generated as the dope is concentrated is removed. Two third filtration devices 30 </ b> C are arranged in parallel and sent to the selected third filtration device 30 </ b> C via the switch 29.
[0036]
The dope that has passed through the third filtration device 30C is then sent to the in-line mixer 41, and a dispersion in which fine particles (for example, a matting agent) are dispersed in a solvent from the fine particle dispersion tank 42 flows into the dope flowing through the in-line mixer 41. Added. The amount of the fine particle dispersion added to the in-line mixer 41 is adjusted by the flow rate adjusting valve 43. In this case, as the solvent for dispersing the fine particles, it is preferable to use the same solvent as the solvent in which the polymer is dissolved in the dissolution tank 12 in order to uniformly disperse the fine particles in the dope. Thus, by providing the in-line mixer 41 for adding and mixing the fine particle dispersion downstream of the filtering devices 30A to 30B and the concentrating device 35 arranged in the dope preparation line 10, aggregation of fine particles can be effectively suppressed. In addition, the fine particles do not clog the filter 40 of the filtration devices 30A to 30B. The in-line mixer 41 may be any device that continuously mixes the dope and the fine particle dispersion, and for example, a static mixer can be suitably used. The static mixer is a stationary mixer without a drive unit, and includes a plurality of elements 92 each having a shape obtained by twisting a rectangular plate 180 ° in a cylindrical casing 90 as shown in FIG. . The element 92 includes a right element 92 (A) and a left element 92 (B) that are twisted in different directions, and the right element 92 (A) and the left element 92 (B) are alternately shifted by 90 °. Placed in. When two kinds of liquids are fed to the static mixer configured in this way, the two kinds of liquids are divided into two parts by the element 92, and the central part and the peripheral part in the casing 90 are changed along the element 92. The fine particle dispersion can be uniformly mixed in the dope under the conversion effect and the reversal effect of changing the rotation direction for each element 92. The dope mixed with the fine particle dispersion is sent to the dope tank 33.
[0037]
Next, the dope prepared as described above in the dope preparation line 10 is sent to the film production line 50 to form a film.
[0038]
As shown in FIG. 4, the film deposition line 50 is composed of a band zone 51 and a drying zone 52. However, the film deposition line 50 used in the present invention is limited to the illustrated one. It is not something. The dope tank 33 (see also FIG. 1) charged with the dope described above is connected to the film forming line 50 via the pump 53 and the guarantee filter 54. In the dope preparation line 10, the guarantee filter 54 removes foreign matter that should be mixed into the dope from the outside of the dope preparation line 10 when the filters 40 of the first to third filtration devices 30A to 30C are replaced, or the like. The tank 33 is attached to remove dust, dust and the like contained in the atmosphere while the dope is charged. The dope tank 33 is provided with a stirring blade 56 that is rotated by a motor 55 so that the dope is always uniform.
[0039]
The band zone 51 is provided with an endless casting band 59 that is stretched around the support rollers 57 and 58, and the support rollers 57 and 58 are rotated by a driving device (not shown). A casting die 60 is provided on the casting band 59. The dope is fed from the dope tank 33 by the pump 53, and after being filtered by the filter 54, the dope is sent to the casting die 60.
[0040]
The casting die 60 casts the dope onto the casting band 59. The dope is gradually dried until it has a self-supporting property while being conveyed by the casting band 59, and is peeled off from the casting band 59 by the peeling roller 61 to form a film 62. The film 62 is dried while being conveyed by the tenter device 63. At this time, it is preferable that at least one axis is extended to a predetermined width. The film 62 sent from the tenter device 63 to the drying zone 52 is wound around a plurality of rollers 64 in the drying zone 52 and dried. The temperature in the drying zone 52 is preferably controlled in the range of 50 to 150 ° C. for uniform drying of the film 62. The dried film 62 is taken up by a take-up device 65.
[0041]
In addition, although the polymer used for this invention is not specifically limited, It is preferable to use a cellulose ester. Among the cellulose esters, it is preferable to use cellulose acylate, and it is particularly preferable to use cellulose acetate. Further, among the cellulose acetates, it is most preferable to use cellulose triacetate (TAC) having an average acetylation degree of 57.5 to 62.5% (substitution degree: 2.6 to 3.0). The degree of acetylation means the amount of bound acetic acid per unit weight of cellulose. The degree of acetylation follows the measurement and calculation of the degree of acetylation in ASTM: D-817-91 (test method for cellulose acetate and the like). In the present invention, cellulose acylate particles are used, and 90% by weight or more of the particles used have a particle diameter of 0.1 to 4 mm, preferably 1 to 4 mm. Also, preferably 95% by weight or more, more preferably 97% by weight or more, further preferably 98% by weight or more, and most preferably 99% by weight or more of particles have a particle size of 0.1 to 4 mm. Furthermore, it is preferable that 50% by weight or more of the particles used have a particle diameter of 2 to 3 mm. More preferably 70% by weight or more, still more preferably 80% by weight or more, and most preferably 90% by weight or more of the particles have a particle size of 2 to 3 mm. The particle shape of the cellulose acylate is preferably as close to a sphere as possible.
[0042]
The solvent used in the present invention can be a chlorinated organic solvent as a main solvent or a non-chlorine organic solvent as a main solvent. preferable. This is because it is not only preferable for the environment, but a solvent containing a non-chlorine organic solvent as a main solvent has a greater effect of extending the filtration life when the hydrophobic filter 40 is used.
[0043]
The chlorinated organic solvent generally means a halogenated hydrocarbon compound, and representative examples include dichloromethane (methylene chloride) and chloroform, but are not limited thereto. Non-chlorine organic solvents include, but are not limited to, esters, ketones, ethers, and alcohols. The solvent is not particularly limited as long as it is commercially available. The solvent may be used alone (100% by weight) or may be a mixture of esters having 1 to 6 carbon atoms, ketones, ethers and alcohols. Examples of solvents that can be used include esters (eg, methyl acetate, methyl formate, ethyl acetate, amyl acetate, butyl acetate, etc.), ketones (eg, acetone, methyl ethyl ketone, cyclohexanone, etc.), ethers (eg, dioxane). , Dioxolane, tetrahydrofuran, diethyl ether, methyl-t-butyl ether, etc.) and alcohols (eg, methanol, ethanol, butanol, etc.). The organic solvent used in the present invention may be a mixture of the above-described chlorinated organic solvent and non-chlorinated organic solvent.
[0044]
As a plasticizer added to the dope of the present invention, phosphate ester type (for example, triphenyl phosphate (hereinafter referred to as TPP), tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, diphenyl biphenyl phosphate (hereinafter referred to as “Phenyl diphenyl phosphate”) , BDP), trioctyl phosphate, tributyl phosphate, etc.), phthalate ester type (eg, diethyl phthalate, dimethoxyethyl phthalate, dimethyl phthalate, dioctyl phthalate, etc.), glycolate ester type (eg, triacetin, tributyrin, butyl phthalate, etc.) Rubutyl glycolate, ethyl phthalyl ethyl glycolate, methyl phthalyl ethyl glycolate, butyl phthalyl butyl glycolate, etc.) and other plasticizers It is possible to have.
[0045]
As an ultraviolet absorber, for example, an oxybenzophenone compound, a benzotriazole compound, a salicylic acid ester compound, a benzophenone compound, a cyanoacrylate compound, a nickel acetate compound, and other ultraviolet absorbers can be used. Particularly preferred ultraviolet absorbers are benzotriazole compounds and benzophenone compounds.
[0046]
As fine particles, for example, a matting agent, the average height of the projections on the surface is preferably 0.005 to 10 μm, more preferably 0.01 to 5 μm. In addition, it is better that there are many protrusions on the surface, but if there are more protrusions than necessary, it becomes a problem and becomes a problem. A preferable protrusion is within a range having an average height of the protrusion, for example, when the protrusion is formed with a spherical or irregular matting agent, the content is 0.5 to 600 mg / m ² , and more preferable. Is 1 to 400 mg / m ² .
[0047]
The matting agent is not particularly limited as long as it is a material exhibiting the above-mentioned function, but preferred specific examples of these matting agents include compounds containing silicon, silicon dioxide, titanium dioxide, zinc oxide, aluminum oxide, Barium oxide, zirconium oxide, strongtium oxide, antimony oxide, tin oxide, tin antimony oxide, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate, In addition, calcium phosphate and the like are preferable, and silicon-containing inorganic compounds and zirconium oxide are more preferable. However, since the turbidity of the cellulose triacetate film can be reduced, silicon dioxide is particularly preferably used. As fine particles of silicon dioxide, for example, commercially available products having trade names such as Aerosil R972, R974, R812, 130, 200, 300, R202, OX50, TT600 (manufactured by Nippon Aerosil Co., Ltd.) can be used. As the fine particles of zirconium oxide, for example, those commercially available under trade names such as Aerosil R976 and R811 (manufactured by Nippon Aerosil Co., Ltd.) can be used.
[0048]
Examples of organic compound matting agents include polytetrafluoroethylene, cellulose acetate, polystyrene, polymethyl methacrylate, polypropylene methacrylate, polyethylene carbonate, acrylic styrene resin, silicone resin, polycarbonate resin, benzoguanamine resin, and melamine resin. Polyolefin powder, polyester resin, polyamide resin, polyimide resin, polyfluorinated ethylene resin, and pulverized classification of organic polymer compounds such as starch, among which silicone resin is preferably used. Among the silicone resins, those having a three-dimensional network structure are particularly preferable. For example, Tospearl 103, Tospearl 105, Tospearl 108, Tospearl 120, Tospearl 145, Tospearl 3120, Tospearl 240 (manufactured by Toshiba Silicone Co., Ltd.) A commercial product having the trade name of can be used.
[0049]
Furthermore, various other additives such as a mold release agent, a release accelerator, and a fluorine interfacial adhesive may be added to the dope at any stage after preparation of the dope as necessary. Also good.
[0050]
In FIG. 4, the film forming line 50 using the single-layer casting die 60 is described as an example. However, as shown in FIG. 5, the solution by co-casting with the casting die 70 having a multi-manifold is used. It can also be applied to a film forming method. The casting die 70 is provided with a plurality of (three in FIG. 5) manifolds. The manifolds 71, 72, and 73 are doped with the dope for the back layer, the dope for the intermediate layer, and the dope for the surface layer prepared by the above-described dope preparation line, respectively. After that, the casting ribbon 74 is cast on the casting band 75 to form a film. The co-casting method is not limited to the illustrated multi-manifold method, and may be performed by a known method such as a feed block method.
[0051]
FIG. 6 is a part of an outline of an example in which the present invention is applied to a solution casting method for sequential casting (sequential casting). In this method, an endless casting band 82 is provided around the support rollers 80 and 81. When the support rollers 80 and 81 are rotated by a driving device (not shown), the casting band 82 rotates. Two casting dies 83 and 84 are disposed on the casting band 82, and from each casting die 83 and 84, the dope for the back layer and the surface layer prepared in the dope preparation line 10 described above. The dope is cast and a film is formed. In the present invention, film formation by sequential casting is not limited to the two casting dies shown in the figure, and three or more casting dies may be used.
[0052]
【Example】
Although the Example and comparative example of the dope preparation method of this invention are demonstrated below, it is not limited to this.
[0053]
In the dope preparation line shown in FIG. 1, the filtration lifetimes of the first to third filtration devices were compared when the timing of adding the fine particles was performed at the following five positions.
[0054]
Test 1... As shown by (1) in FIG. 1, fine particles were added simultaneously when the cellulose acylate raw material was dissolved in the solvent in the dissolution tank.
[0055]
Test 2 As shown by (2) in FIG. 1, fine particles were added between the first filtration device and the second filtration device.
[0056]
Test 3... As shown in FIG. 1 (3), fine particles were added at a position between the second filtration device and the concentration device.
[0057]
Test 4 As shown in (4) of FIG. 1, fine particles were added between the concentrating device and the third filtering device.
[0058]
Test 5: As shown in (5) in FIG. 1, a static mixer is added with fine particles, which is the addition position according to the present invention.
[0059]
Then, when the filtration lifetimes of the first to third filtration devices at the time of test 5 were used as a reference, the filtration lifetimes of tests 1, 2, 3, and 4 were compared. .
[0060]
As a result, in the case of Test 1, the fine particles could not be dispersed uniformly, and the average filtration life of the first to third filtration devices in Test 1 was the average filtration life of the first to third filtration devices. 30% shorter than
[0061]
In the case of Test 2, the filtration life of the second filtration device was 20% shorter than the filtration life of the second filtration device in Test 5.
[0062]
In the case of Test 3, aggregation of fine particles occurs in the concentration device, and the filtration life of the third filtration device arranged downstream of the concentration device is compared with the filtration life of the third filtration device in Test 5. 30% shorter.
[0063]
In the case of Test 4, the filtration life of the third filtration device was 20% shorter than the filtration life of the third filtration device in Test 5.
[0064]
As described above, according to the dope preparation method and the solution casting method according to the present invention, aggregation of fine particles added to the dope can be effectively suppressed. In this case, the clogging of the filter medium can be alleviated and the quality of the film produced by casting the dope can be improved.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration example of a dope preparation line for performing a dope preparation method in a solution casting method of the present invention. FIG. 2 shows an example of a filtration apparatus used in the dope preparation method of the present invention. FIG. 3 is an explanatory diagram for explaining a static mixer in the dope preparation method of the present invention. FIG. 4 is a conceptual diagram showing a configuration example of a film film forming line in the solution film forming method of the present invention. FIG. 5 is a schematic diagram of the main part of another embodiment used in the solution casting method of the present invention. FIG. 6 is a schematic diagram of the main part of another embodiment used in the solution casting method of the present invention. Description】
DESCRIPTION OF SYMBOLS 10 ... Dope preparation line, 12 ... Dissolution tank, 20 ... Storage tank, 25 ... Heater, 26 ... Cooler, 30A ... 1st filtration apparatus, 30B ... 2nd filtration apparatus, 30C ... 3rd filtration apparatus, 34 ... heater, 35 ... concentrator, 36 ... cooler, 40 ... filter, 41 ... in-line mixer, 42 ... fine particle dispersion tank, 50 ... film-forming line, 59 ... casting band, 60 ... casting die, 62 ... Film, 63 ... Tenter device, 52 ... Drying device, 65 ... Winding device

Claims (14)

A dope preparation method comprising: a dope preparation line for preparing a dope prepared by dissolving a polymer in a solvent; and a concentration step for concentrating the dope and an addition step for adding fine particles into the dope, wherein the step is performed after the concentration step. A dope preparation method characterized by arranging an addition step. 2. The dope preparing method according to claim 1, wherein the polymer solution is a cellulose acylate solution. The dope preparation method according to claim 1, wherein the dope preparation line includes a filtration step, and the addition step is arranged after the concentration step and the filtration step. The dope preparation according to any one of claims 1 to 3, wherein a dispersion liquid in which the fine particles are dispersed in the same solvent as the solvent for dissolving the polymer or a solution composed of the same solvent is added in the addition step. Method. The dope preparation method according to any one of claims 1 to 4, wherein the solvent contains a non-chlorine organic solvent as a main solvent. A solution casting method comprising casting a dope prepared by the dope preparing method according to any one of claims 1 to 5 on a casting support to form a film. 7. The solution casting method according to claim 6, wherein the dope is formed by a co-casting method. A film formed by the solution casting method according to claim 6 or 7. A polarizing plate protective film manufactured using the film of claim 8. A polarizing plate produced using the polarizing plate protective film according to claim 9. A liquid crystal display device manufactured using the polarizing plate according to claim 10. An optical compensation film produced using the film of claim 8. A liquid crystal display device manufactured using the optical compensation film according to claim 12. A photographic light-sensitive material produced using the film of claim 8.

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