JP2004107629A - Method for casting film from solution - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for casting a film from solution, capable of improving the absolute filtration accuracy of a cellulose acylate solution without decreasing the hole diameter of a filtering material and increasing the amount of the filtration treatment. <P>SOLUTION: This method for casting the film from the solution is provided by firstly introducing dope stock solution before filtration firstly into a body feed tank 28 and adding a filtering aid from a filtering aid tank 37 for dispersing. As the filtering aid, an aid having ≥50 % SiO<SB>2</SB>and a cellulose-based aid are mixed and used. The dope stock solution dispersed with the filtering aid is introduced to a filter 30 and filtered while forming a cake on the surface of the filtering material. After the filtration, a cleaning solution is supplied as circulating from a cleaning solution tank 38 and the cake is discharged as slurry. The filtering aid is separated from the slurry in a separating device 44, and the filtering aid is fired in a firing device 48. Regenerated filtering aid is sent to the filtering aid tank 37. After the cleaning treatment, a pre-coating liquid dispersed with the filtering aid is supplied to the filter 30 to form a pre-coat layer on the surface of the filtering material. <P>COPYRIGHT: (C)2004,JPO

Description

次に、得られたフィルムを用いて防眩性反射防止偏光板を作製した。この偏光板を用いて反射防止層を最表層に配置した液晶表示装置を作製したところ、外光の映り込みがないために優れたコントラストが得られ、防眩性により反射像が目立たず、優れた視認性を有し、指紋付も良好であった。
（防眩層塗布液の調製）
ジペンタエリスリトールペンタアクリレートとジペンタエリスリトールヘキサアクリレートの混合物（ＤＰＨＡ、日本火薬（株）製）１２５ｇ、ビス（４−メタクリロイルチオフェニル）スルフィド（ＭＰＳＭＡ、住友精化（株）製）１２５ｇを４３９ｇのメチルエチルケトン／シクロヘキサノン＝５０／５０重量％の混合溶媒に溶解した。得られた溶液に光重合開始剤（イルガキュア９０７、チバガイギー社製）５．０ｇおよび光増感剤（カヤキュアーＤＥＴＸ、日本火薬（株）製３．０ｇを４９ｇのメチルエチルケトンに溶解した溶液を加えた。この溶液を塗布、紫外線硬化して得られた塗膜の屈折率は１．６０であった。
【００８０】
さらにこの溶液に平均粒径２μｍの架橋ポリスチレン粒子（商品名：ＳＸー２００Ｈ、綜研化学（株）製）１０ｇを添加して、高速ディスパにて５０００ｒｐｍで１時間攪拌、分散した後、孔径３０μｍのポリプロピレン製フィルターで濾過して防眩層の塗布液を調製した。
（ハードコート層用塗布液の調製）
紫外線硬化性ハードコート組成物（デソライトＫＺー７６８９、７２重量％、ＪＳＲ（株）製）２５０ｇを６２ｇのメチルエチルケトン、および８８ｇのシクロヘキサノンに溶解した溶液を加えた。この溶液を塗布、紫外線硬化して得られた塗膜の屈折率は１．５３であった。
【００８１】
さらにこの溶液を孔径３０μｍのポリプロピレン製フィルターで濾過してハードコート層の塗布液を調製した。
（低屈折率層塗布液の調製）
屈折率１．４２の熱架橋性含フッ素ポリマー（ＴＮ−０４９、ＪＳＲ（株）製）２００９３ｇにＭＥＫーＳＴ（平均粒径１０〜２０ｎｍ、固形分濃度３０重量％のＳｉＯ_２ゾルのＭＥＫ分散物、日産化学（株）製）８ｇ、およびルエチルケトン１００ｇを添加、攪拌の後、孔径１μｍのポリプロピレン製フィルターで濾過して、低屈折率層用塗布液を調製した。
【００８２】
【発明の効果】
以上説明したように本発明に係る溶液製膜方法によれば、濾過助剤を用いてセルロースアシレート溶液の濾過処理を行うので、濾材の目詰まりを抑制でき、濾過寿命を延長させることができるとともに、濾過精度を向上させることができる。
【図面の簡単な説明】
【図１】本発明に係る濾過機の洗浄方法が適用されるドープ製造ラインの構成図
【図２】フィルム製膜装置の構成図
【図３】本発明に係る濾過機の洗浄装置の構成図
【符号の説明】
１０…ドープ製造ライン、１１…溶媒タンク、１２…溶解タンク、１４…計量器、１５…可塑剤タンク、２０…貯蔵タンク、２７…ポンプ、２８…ボディフィード用タンク、２９…切替器、３０…濾過機、３１…流量計、３２…ドープ、３３…ドープ用タンク、３４…洗浄溶剤回収タンク、３６…リサイクル溶液タンク、３７…濾過助剤タンク、３８…洗浄溶剤タンク、３９…ポンプ、４０…排出タンク、４１…攪拌翼、４２…フィルタ部材、４３…排出ライン、４４…分離装置、４６…回収ライン、４７…加熱器、４８…焼成装置、４９…プレコート用タンク、５０…フィルム製膜装置、５１…バンドゾーン、５２…乾燥ゾーン、５４…フィルタ、５９…流延バンド、６０…流延ダイ、６１…剥ぎ取りローラ、６２…フィルム、６３…テンタ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a solution casting method, and more particularly to a solution casting method for producing a cellulose acylate film used for a liquid crystal display device or a photographic light-sensitive material.
[0002]
2. Description of the Related Art In the process for producing a cellulose acylate film, a cellulose acylate solution is first prepared by dispersing and stirring cellulose ester flakes and a solvent. Then, the cellulose acylate solution is filtered to remove foreign substances, thereby eliminating the possibility of film defects after film formation. Next, the filtered cellulose acylate solution is formed into a film and dried by co-casting or the like. Thereby, a cellulose acylate film is manufactured.
[0003]
The filtration treatment of the cellulose acylate solution described above is carried out for the purpose of removing foreign matters such as undissolved materials and insoluble materials in the dope and preventing the occurrence of defects in the formed film. Filter media, filter cloth, sintered metal, etc. are used as filter media for filtration treatment, but the problem is that the filter media pores will eventually close in any filter media, causing a sudden increase in differential pressure in the latter half of the filtration treatment. There is. For this reason, it is necessary to periodically pass the cleaning solution through the filter medium and to wash and regenerate the filter medium.
[0004]
By the way, the current filtration process uses a filter medium having an absolute filtration accuracy of about 0.01 mm, but it is expected that the required filtration accuracy will increase in the future. In particular, cellulose acylate films for liquid crystal displays in recent years are required to have higher quality than photographic cellulose acylate films, and absolute filtration accuracy is inevitably improved.
[0005]
[Problems to be solved by the invention]
However, if the pore size of the filter medium is reduced for the purpose of improving the absolute filtration accuracy, the filter medium is immediately clogged, resulting in a very short filter life. Moreover, in recent years, the manufacturing process of a cellulose acylate film has been accelerated, and this also causes a shortening of the filtration blockage time. When the filter medium closing time is shortened, the frequency of cleaning increases, so the burden on the operator increases.
[0006]
In addition, when the pore size of the filter medium is reduced, there arises a problem that a high filtration pressure is required and a problem that productivity is lowered due to a long time for the filtration treatment.
[0007]
The present invention has been made in view of such circumstances, and a solution that can improve the absolute filtration accuracy of a cellulose acylate solution and increase the amount of filtration treatment without reducing the pore size of the filter medium. It aims at providing the film forming method.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 is a solution casting method in which a cellulose acylate solution is prepared and filtered, and then a cellulose acylate film is manufactured to form a cellulose acylate film. , Using a filter aid.
[0009]
According to the first aspect of the present invention, since the cellulose acylate solution is filtered using the filter aid, clogging of the filter medium can be suppressed. Therefore, a rapid pressure increase in the latter half of the filtration process can be suppressed, and the filtration life can be extended. In addition, the filtration treatment using the filter aid is a sieving effect due to a physical gap formed between the foreign substance contained in the cellulose acylate solution and the filter aid, or adsorption by interaction with the filter aid. Depending on the effect, high filtration accuracy can be achieved. Furthermore, the filtration process using the filter aid can reduce the burden on the operator because the cake can be peeled off by backwashing or rotation of the filter medium and the system can be washed with the system closed.
[0010]
According to the invention described in claim 2, 50% or more of the composition of the filter aid is SiO 2. ₂ It was. SiO ₂ Adsorbs the insoluble matter in the cellulose acylate solution, so that impurities can be reduced. Therefore, the quality of the film after film formation can be improved. In addition, SiO ₂ The ratio is more preferably 70% or more, and further preferably 90% or more.
[0011]
According to the invention described in claim 3, since the cellulose-based auxiliary is used as the filter auxiliary, it is possible to adsorb insoluble matter in the cellulose acylate solution.
[0012]
According to the invention described in claim 4, the cellulosic auxiliary agent and SiO ₂ A mixture with more than 50% auxiliary was used. Such a mixing system can make the cake layer sturdy. In addition, SiO ₂ Is more preferably 70% or more, and more preferably 90% or more of an auxiliary.
[0013]
According to invention of Claim 5, the filter aid which consists of a some mixture was used. Thus, the use of mixtures of different particle sizes can extend the cake's filtration life. If an auxiliary agent having a large particle size is arranged on the upstream side and an auxiliary agent having a small particle size is arranged on the downstream side, the filtration efficiency can be improved.
[0014]
According to invention of Claim 6, the average particle diameter of the filter aid was prescribed | regulated to 1-150 micrometers. If the average particle size of the filter aid is smaller than this range, the cake layer becomes dense and the filtration resistance increases. For this reason, a high filtration pressure is required and the apparatus becomes large. On the other hand, when the average particle size of the filter aid is large, the gap between the cake layers is increased, and the filtration accuracy is lowered. Therefore, when filtering a cellulose acylate solution, it is preferable to use a filter aid having an average particle size in the above range. Here, the average particle diameter is an average particle diameter of an aggregate formed by collecting atoms or molecules. In addition, the average particle diameter of the filter aid is more preferably 10 to 100 μm, and further preferably 20 to 50 μm.
[0015]
In the seventh aspect of the present invention, the standard deviation of the particle size of the filter aid is specified to be ½ average particle size or less. If the standard deviation is small as described above, the dispersion of the particle size of the filter aid is small, so that a stable cake can be formed. The standard deviation is more preferably 0.4 average particle size or less, and further preferably 0.3 average particle size or less.
[0016]
The invention according to claim 8 has a bulk density of the filter aid of 0.01 to 0.8 g / cm. ³ Stipulated in the range. When the bulk density is smaller than this range, the voids of the cake are increased, and the filtration accuracy is lowered. Conversely, if the bulk density is large, the filtration resistance increases and the apparatus becomes large. For this reason, when filtering a cellulose acylate solution, it is preferable that the average particle diameter of a filter aid is the said range. The bulk density is 0.1 to 0.5 g / cm. ³ Is more preferable, 0.3 to 0.4 g / cm ³ The range of is more preferable.
[0017]
According to the ninth aspect of the present invention, the amount of the filter aid added to the cellulose acylate solution is 0.01 to 10 wt. %. When the addition amount of the filter aid is smaller than this range, the clogging prevention effect by the filter aid is hardly obtained. Conversely, if the amount of filter aid added is large, the rate of increase in the thickness of the cake layer is large, and the resistance of the cake layer increases rapidly with this, so the cake must be frequently washed and discharged. . Therefore, the amount of filter aid added is preferably in the above range. In addition, the addition amount of the filter aid is 0.05 to 5 wt. % Is more preferable, and 0.1 to 0.5 wt. % Range is more preferred.
[0018]
In the invention described in claim 10, the precoat thickness of the filter aid is regulated to 0.1 to 10 mm. If the thickness of the precoat is smaller than this range, the initial filtration accuracy is deteriorated. Conversely, if the thickness of the precoat is thick, the initial resistance is increased, and the apparatus is increased in size. For this reason, the precoat thickness is defined as described above. The precoat thickness is preferably 0.5 to 5 mm, more preferably 1 to 2 mm.
[0019]
In the invention according to claim 11, the mass of the precoat is 0.1 to 5 kg / m. ² Stipulated. If the precoat is lighter than this range, the initial filtration accuracy deteriorates. If the precoat is heavy, the initial resistance increases and the apparatus becomes large. For this reason, the mass of a precoat is prescribed | regulated as mentioned above. The mass of the precoat is 0.5-2 kg / m. ² Is more preferable.
[0020]
According to the invention described in claim 12, the terminal speed of the filter aid is 10 ^-4 It was defined as ˜1 cm / s. If the terminal speed is higher than this range, a uniform precoat layer cannot be formed. Conversely, if it is small, it takes a long time to form the precoat layer, which is not practical. Therefore, a uniform precoat layer can be rapidly formed by defining the terminal speed of the filter aid as described above. The terminal speed of the filter aid is 10 ^-4 -10 ^-2 More preferred is cm / s. ^-4 -10 ^-3 More preferred is cm / s.
[0021]
According to invention of Claim 13, the filtration flow rate was prescribed | regulated to 0.1-50 cm / hr. When the filtration flow rate is lower than this range, the filtration efficiency is lowered. On the other hand, when the filtration flow rate is higher, the filtration accuracy is lowered or the filtration pressure becomes very large. The filtration flow rate is more preferably 0.5 to 30 cm / hr, and further preferably 1 to 15 cm / hr.
[0022]
According to the invention described in claim 14, the initial filtration differential pressure is defined as 0.01 to 1 MPa. Thus, the filtration accuracy can be improved by setting the initial filtration differential pressure in a low range. Further, the pressure range for subsequent filtration can be widened, and long-time filtration and a large filtration amount can be obtained. Here, the filtration initial differential pressure indicates a pressure difference between the primary side and the secondary side of the filter medium in the initial stage of filtration. The initial filtration differential pressure is more preferably 0.01 to 0.5 MPa, further preferably 0.01 to 0.1 MPa.
[0023]
According to the invention of the fifteenth aspect, the filtration treatment is performed at a filtration pressure of 0.01 to 4 MPa. If the filtration pressure is higher than this range, the equipment cost for pressure resistance increases and the apparatus becomes large. On the other hand, if it is low, the cellulose acylate solution may boil. Here, the filtration pressure indicates the pressure on the primary side of the filter medium. The filtration pressure is more preferably from 0.01 to 2 MPa, further preferably from 0.01 to 1 MPa.
[0024]
According to invention of Claim 16, the filtration differential pressure was prescribed | regulated to 0.01-3 MPa. When the filtration differential pressure is larger than this range, the cake layer is crushed. As a result, the cake is compressed and densified, which further increases the filtration differential pressure. Further, the cake is crushed so that the inside of the layer is disturbed, and the filter aid is mixed into the dope after filtration. On the contrary, if the filtration differential pressure is smaller than the above range, the cake layer may be peeled off. Therefore, the cake layer can be stably formed by defining the filtration differential pressure as described above. Here, the filtration differential pressure indicates a pressure difference between the primary side and the secondary side of the filter medium.
[0025]
According to invention of Claim 17, the thickness of the cake layer was prescribed | regulated to 0.1-80 mm. If the thickness of the cake layer is larger than this range, the pressure loss increases and a high filtration pressure is required. On the contrary, if the thickness of the cake layer is small, the filtration accuracy deteriorates. In order to control the thickness of the cake layer within the above range, the cake layer may be exchanged until the thickness reaches 80 mm.
[0026]
According to the invention described in claim 18, the filtration is performed under a pressure condition that does not boil and at a temperature 20 ° C. lower than the boiling point of the cellulose acylate solution at normal pressure. The higher the filtration temperature is, the lower the viscosity of the liquid is and the cake resistance is reduced, thereby suppressing an increase in the filtration differential pressure.
[0027]
According to the nineteenth aspect of the present invention, the filter aid is dispersed in the cellulose acylate solution in the range of the boiling point of the cellulose acylate solution at normal pressure and the temperature lower than the boiling point by 20 ° C. When the filter aid is dispersed in the above temperature range, the air dissolved in the cellulose acylate solution is foamed using the filter aid as a core, so that the cellulose acylate solution is defoamed. Thus, the invention of claim 19 has an effect of not only prolonging the filter life but also defoaming at the same time. Furthermore, in the invention described in claim 19, since the filtration treatment is performed after the dissolved bubble saturation at the filtration temperature in the cellulose acylate solution becomes 90% or less, foaming is performed during the filtration treatment. It can be suppressed as much as possible. Thereby, the fall of the film quality accompanying foaming can be prevented. In addition, the dissolved bubble saturation at the time of performing the filtration treatment is more preferably 80% or less, and further preferably 70% or less.
[0028]
According to the twentieth aspect of the invention, the filtration treatment is performed at a lower temperature than when the filter aid is dispersed. In other words, the filtration treatment was performed in an environment where foaming was less likely to occur than when the filter aid was dispersed. Thereby, foaming at the time of a filtration process can be prevented, and film quality can be improved.
[0029]
According to the invention as set forth in claim 21, the concentration of the filter aid leaking from the filter is regulated to 10,000 pieces / cc or less. In this way, by suppressing the leakage of the filter aid, it is possible to prevent defects due to quality deterioration of the film after film formation and contamination with foreign matter. The concentration of the filter aid is more preferably 5000 / cc or less, and still more preferably 1000 / cc or less.
[0030]
According to the invention of claim 22, since a filter having an absolute filtration accuracy of 2 to 50 μm is installed after the filtration process as a filter aid trap, and the subsequent filtration process is performed, the leaked filter aid And the filter aid can be prevented from being mixed into the film. The absolute filtration accuracy of the filter is more preferably 2 to 30 μm, and further preferably 5 to 15 μm.
[0031]
According to the twenty-third aspect of the present invention, since the filter is backwashed with the cleaning solvent, the cake can be peeled off from the filtration support. According to the invention of claim 23, since the cleaning solvent is heated and supplied at a temperature not lower than the boiling point of the cellulose acylate solution at a temperature not lower than the boiling point of the cellulose acylate solution, it is peeled off. The cake can be efficiently discharged as a slurry. Incidentally, conventionally, since the filter medium was opened and the filter medium was exchanged, the organic solvent came out of the container, the working environment was deteriorated, and the working time was long. However, in the invention of claim 23, since the cake can be moved as a slurry in the pipe, it can be moved and processed in a sealed system. Therefore, the working environment is good and the time can be shortened.
[0032]
According to invention of Claim 24, the cake formed by the filtration process is 1-50 kg / m. ³ It was made to discharge | emit as a slurry of the density | concentration range. When the concentration of the slurry at the time of discharge is lower than this range, the cake discharge efficiency is deteriorated. On the other hand, if the concentration is high, there is a problem that the particles of the slurry are condensed. Therefore, the cake can be efficiently and reliably discharged by setting the slurry concentration within the above range. As described in claim 25, the discharged slurry can be reused as a precoat liquid or a body feed liquid. The concentration range of the slurry is 10 to 40 kg / m. ³ Is more preferable, 20-30 kg / m ³ Is more preferable.
[0033]
According to the invention of claim 26, a non-chlorine organic solvent is used. In recent years, it has been desired to use a non-chlorinated solvent due to environmental influences. The non-chlorine organic solvent may be any of a cellulose acylate solution, a precoat solution, a body feed solution, and a cleaning solvent, but it is preferable to use a non-chlorine solution in all the solutions. In addition, when a non-chlorine type dope is used, since the dope is prepared by a cooling dissolution method and a large amount of gas is dissolved, a more remarkable effect of the defoaming described above can be obtained.
[0034]
According to the invention of claim 27, since the discharged cake slurry is separated into a solvent and a filter aid, and the filter aid is baked at 400 ° C. or higher for regeneration, the regeneration efficiency of the filter aid is improved. Can be improved. Furthermore, according to the invention described in claim 28, since the regenerated filter aid is mixed with an unused filter aid and used, the cost can be reduced without degrading the performance as a filter aid. Can do.
[0035]
The cellulose acylate solution subjected to the above filtration treatment is preferably formed into a film by co-casting as described in claim 29. The formed cellulose acylate film can satisfy high quality as described in claim 31. Therefore, it can be used as a protective film for a polarizing plate as in the thirty-second aspect, and a liquid crystal display device can be produced as in the thirty-fourth aspect using the polarizing plate. Further, an optical compensation film can be produced as described in claim 33 using the formed cellulose acylate film, and a liquid crystal display device as described in claim 35 can be produced using the optical compensation film. Can be manufactured. The film thus formed can be used as a photographic material as described in claim 36.
[0036]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of a solution casting method according to the present invention will be described in detail with reference to the accompanying drawings.
[0037]
FIG. 1 is an overall configuration diagram showing a dope production line 10 in which the solution casting method according to the present invention is adopted.
[0038]
As shown in the figure, the dope production line 10 is provided with a solvent tank 11, a meter 14, and a plasticizer tank 15.
[0039]
A solvent is stored in the solvent tank 11. The main solvent of this solvent may be a chlorinated organic solvent or a non-chlorinated organic solvent. Here, the chlorinated organic solvent generally means a halogenated hydrocarbon compound, and examples thereof include dichloromethane (methylene chloride) and chloroform. Non-chlorine organic solvents include esters (eg, methyl acetate, methyl formate, ethyl acetate, amyl acetate, butyl acetate), ketones (eg, acetone, methyl ethyl ketone, cyclohexanone), ethers (eg, dioxane, dioxolane, Tetrahydrofuran, diethyl ether, methyl-t-butyl ether), alcohols (for example, methanol, ethanol, butanol) and the like. This non-chlorine organic solvent may be used alone (100% by weight), or may be used by mixing esters having 1 to 6 carbon atoms, ketones, ethers and alcohols. It is also possible to use a mixture of the above-mentioned chlorinated organic solvent and non-chlorinated organic solvent. Moreover, the kind of solvent is not limited to what was mentioned above.
[0040]
The meter 14 is charged with a polymer. As the polymer, it is preferable to use a cellulose ester, particularly cellulose acylate. Furthermore, among cellulose acylates, it is preferable to use cellulose acetate, and cellulose triacetate (TAC) having an average oxidation degree of 57.5 to 62.5% (substitution degree: 2.6 to 3.0) is preferably used. Most preferably it is used. Here, the degree of oxidation means the amount of bound acetic acid per unit weight of cellulose, and follows the measurement and calculation of the degree of acetylation in ASTM: D-817-91 (test method for cellulose acetate and the like). As the polymer, cellulose acylate particles are used in the present invention. 90% by weight or more of the particles used preferably have a particle diameter of 0.1 to 4 mm, more preferably 1 to 4 mm. Further, it is more preferable that the particles having a particle diameter of 0.1 to 4 mm are 95% by weight or more, more preferably 97% by weight or more, or 98% by weight or more, and most preferably 99% by weight or more. Moreover, it is preferable that the particle | grains with a particle diameter of 2-3 mm are 50 weight% or more of the particle | grains to be used, 70 weight% or more, 80 weight% or more is more preferable, It is most preferable that it is 90 weight% or more. The particle shape of cellulose acylate is preferably as close to a sphere as possible.
[0041]
A plasticizer is stored in the plasticizer tank 15. Examples of plasticizers include phosphate esters (for example, triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, diphenyl biphenyl phosphate, trioctyl phosphate, tributyl phosphate), phthalate esters (diethyl phthalate) , Dimethoxyethyl phthalate, dimethyl phthalate, dioctyl phthalate, etc.), glycolic acid esters (eg, triacetin, tributyrin, butyl phthalyl ethyl glycolate, ethyl phthalyl ethyl glycolate, methyl phthalyl ethyl glycolate, butyl phthalyl butyl glycol) Rate), and other plasticizers. In addition, you may add the other additive of a plasticizer to dope. Examples of other additives include an ultraviolet absorber, a release agent, a release accelerator, and a fluorosurfactant, which may be added at any stage from the preparation of the dope to the preparation.
[0042]
The solvent in the solvent tank 11, the polymer in the meter 14, and the plasticizer in the plasticizer tank 15 are respectively sent to the dissolution tank 12. At that time, the flow rate of the solvent is adjusted by the open / close valve 13, and the flow rate of the plasticizer is adjusted by the open / close valve 16. The polymer is weighed and sent to the solvent tank 11. The amount of the polymer is preferably 15 to 20% by weight based on the solvent in view of the quality of the film product after film formation. The amount of the plasticizer is preferably 5 to 20% by weight with respect to the polymer in consideration of the flexibility of the film product. The order of feeding into the dissolution tank 12 is not particularly limited. For example, it is preferable to supply the plasticizer after first feeding the solvent into the dissolution tank 12 and then feeding the polymer. Further, the plasticizer may be added only when necessary, and other additives may be added.
[0043]
The dissolution tank 12 is provided with a stirring blade 18 that is rotated by a motor 17. As the stirring blade 18 rotates, the solvent, polymer, plasticizer, and the like in the dissolution tank 12 are stirred. Thereby, it will be in the state of coarse dissolution, ie, the state where solutes such as polymers are not completely dissolved in the solvent.
[0044]
The crude solution 19 roughly dissolved in the dissolution tank 12 is temporarily stored in the storage tank 20. Thereby, since the inside of the dissolution tank 12 is emptied, a continuous batch system in which the crude dissolution liquid 19 is repeatedly formed becomes possible. The storage tank 20 is also provided with a stirring blade 22 that is rotated by a motor 21 so that the stored crude solution 19 can be stirred and made uniform.
[0045]
The crude solution 19 in the storage tank 20 is sent to the heater 25 via the pipe 24 by driving the pump 23. As the heater 25, an in-line mixer such as a multi-tube heat exchanger (shell and tube method) or a static mixer (static mixer) is used, and the crude solution 19 is heated by the heater 25. The heating temperature is preferably 50 to 120 ° C., and the heating time is preferably 5 to 30 minutes. Thereby, the solute such as a polymer necessary for film formation is completely dissolved without modification, and a dope stock solution is prepared. Note that the pipe 24 may be kept warm or heated, whereby the crude solution 19 flowing through the pipe 24 is heated to promote dissolution of the solute.
[0046]
The dope stock solution prepared by the heater 25 is sent to the cooler 26, and is cooled by this cooler 26 to below the boiling point of the main solvent constituting the dope stock solution. The cooled dope stock solution is sent to the body feed tank 28 by driving the pump 27.
[0047]
A filter aid tank 37 is connected to the body feed tank 28, and the filter aid is fed from the filter aid tank 37. A filter aid is an inert powder or particle that improves the filtration performance and improves the filtration rate by forming a porous bed on the filter medium. For example, silicon dioxide (SiO 2). ₂ ) Is used by mixing 50% or more of an auxiliary agent and a cellulose-based auxiliary agent. Further, a filter aid having an average particle diameter of 1 to 150 μm is used. When an auxiliary agent having a fine average particle diameter is used, a cake layer having a small void is formed, so that the filtration resistance increases and the filtration rate decreases. On the contrary, when a filter aid having a large average particle size is used, a cake layer having a large void is formed, resulting in a decrease in filtration accuracy.
[0048]
As the filter aid, one having a standard deviation of the particle size of ½ average particle size or less is used. If the standard deviation of the particle diameter is large, the dispersion of the particle diameter is large, so that a stable cake cannot be formed.
[0049]
Further, the filter aid has a bulk density of 0.01 to 0.8 g / cm. ³ Is used. When the bulk density is smaller than this range, a cake layer having a large void is formed, and the filtration accuracy is lowered. Conversely, when the bulk density is large, a cake layer having a small void is formed, and the differential pressure of filtration tends to increase. In addition, the filter aid may use only an assistant containing 50% or more of silicon dioxide, or may use only a cellulose-based assistant. Alternatively, fly ash or sand may be used as a filter aid.
[0050]
The filter aid is added at a rate of 0.01 to 10 wt% with respect to the dope stock solution in the body feed tank 28. When this addition amount is small, it is difficult to obtain the effect of preventing clogging by the filter aid. Conversely, when the addition amount is large, the increase in the thickness of the cake layer increases and the filtration resistance increases.
[0051]
The dope stock solution to which the filter aid is added is stirred by the stirring blade 41 of the body feed tank 28. Thereby, a filter aid is disperse | distributed uniformly. In that case, it is performed in a temperature range from the boiling point of the cellulose acylate solution (dope) at normal pressure to 20 ° C. or less. When the filter aid is dispersed in such a temperature range, the air dissolved in the dope stock solution becomes bubbles with the filter aid as a core, and is defoamed. Then, after the dissolved gas saturation in the dope stock solution becomes 90% or less, the dope stock solution is sent to the filter 30 via the switch 29.
[0052]
Two filters 30 are installed in parallel, and the filter 30 to which the dope stock solution is supplied by the switch 29 is selected. As the filter 30, for example, a multi-filter apparatus is used, and filter paper, filter cloth, sintered metal, or the like is used as the filter medium of the filter 30. Here, the filter medium of the filter 30 means a support for the cake layer. In addition, the filter 30 is not limited to two machines, You may install the 3 or more filter 30 in parallel.
[0053]
When the dope stock solution is supplied to the filter 30, the insoluble matter and the filter aid contained in the dope stock solution are deposited on the surface of the filter medium, and a cake layer having voids is formed on the surface of the filter medium. Thereby, since the rapid increase of the filtration differential pressure can be prevented, stable filtration treatment can be performed. Moreover, since the sieving effect by the physical small gap formed between the filter aid and the insoluble material is obtained, the filtration accuracy is improved. Furthermore, SiO as a filter aid ₂ However, since 50% or more of an auxiliary agent or a cellulose-based auxiliary agent is used, the insoluble matter in the cellulose acylate solution is adsorbed by the filter auxiliary agent, and the filtration accuracy is improved.
[0054]
During the filtration treatment, the thickness of the cake layer is preferably in the range of 0.1 to 80 mm. If it is the thickness of such a range, while being able to maintain a high filtration precision, the increase in the filtration resistance by a cake layer can be suppressed.
[0055]
Moreover, it is preferable to perform a filtration process at low temperature rather than the time of disperse | distributing the filter aid mentioned above. Thereby, since the filtration process is performed in an environment in which foaming is harder than that at the time of dispersion, foaming during the filtration process can be prevented. Therefore, the cake layer can be prevented from being destroyed by foaming during the filtration process, and a stable filtration process can be performed.
[0056]
The temperature during the filtration treatment is preferably lower than that at the time of dispersion and at a temperature not lower than the boiling point of the cellulose acylate solution at a temperature not lower than 20 ° C. under a pressure condition that does not boil. By performing the filtration treatment at such a temperature, the viscosity of the dope is lowered and the resistance to the cake is reduced, so that an increase in the filtration differential pressure can be suppressed.
[0057]
A flow meter 31 is provided on the downstream side of the filter 30, and the pump 27 is controlled so that the measured value of the flow meter 31 is constant in the range of 0.1 to 50 cm / hr, for example. If the filtration flow rate is larger than the above range, the filtration accuracy may be reduced, or the filtration pressure may become very large. Conversely, when the filtration flow rate is small, the filtration efficiency is lowered. The filtration method is not limited to the quantitative filtration method, and other methods such as a constant pressure filtration method may be employed.
[0058]
Further, the filtration differential pressure measured at the front stage and the rear stage of the filter 30 is controlled to be 0.01 to 1 MPa in the initial stage of the filtration process. Further, during the filtration process, the filtration pressure is controlled to be 0.01 to 3 MPa by applying a filtration pressure of 0.01 to 4 MPa. The initial filtration differential pressure and the filtration differential pressure are preferably low. If the filtration differential pressure is high, the cake may be crushed. In addition, when the filtration pressure is high, pressure-resistant equipment is required, and there is a problem that equipment costs are increased. Therefore, it is preferable to control the initial filtration differential pressure, the filtration differential pressure, and the filtration pressure within the above ranges, whereby the filtration treatment can be performed at a low cost without destroying the cake.
[0059]
The dope 32 filtered by the filter 30 is sent to the filter member 42. For example, the filter member 42 having an absolute filtration accuracy of 2 to 50 μm is used. By filtering with the filter member 42, the filter aid leaked from the filter 30 is collected. The filter aid leaking from the filter 30 is preferably in an amount that can be collected by the filter member 42. For example, the amount of auxiliary agent leaking from the filter 30 is preferably 10,000 pieces / cc or less, The number is more preferably 5000 / cc or less, and still more preferably 1000 / cc or less.
[0060]
The dope 32 that has passed through the filter member 42 is sent to the dope tank 33 and stored therein. The dope 32 is formed by the film forming apparatus 50 shown in FIG.
[0061]
A film forming apparatus 50 shown in FIG. 2 includes a band zone 51 and a drying zone 52. The dope 32 charged in the dope tank 33 is fed by a pump 53. Then, after dust and dust are removed by the filter 54, the dust is supplied to the casting die 60 in the band zone 51.
[0062]
The band zone 51 is provided with a pair of support rollers 57 and 58 and an endless casting band 59 wound around the pair of support rollers 57 and 58. The casting band 59 moves around by rotating the support rollers 57 and 58 with a driving device (not shown). The casting die 60 described above is installed on the casting band 59. When the dope 32 is supplied to the casting die 60, the dope 32 is cast on the casting band 59. The cast dope 32 is dried while being transported by the casting band 59, and when it is self-supporting, it is stripped off by the stripping roller 61. Thereby, the film 62 is formed. The film 62 is dried while being conveyed by the tenter 63.
[0063]
The film 62 sent from the tenter 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 controlled in the range of 50 to 150 ° C., and the film 62 is uniformly dried. The dried film 62 is taken up by a winder 65. As a result, the high-quality film 62, that is, the number of bright spot defects observed under crossed Nicols is 5 cm in the width direction. ² 20 μm or more is 0 (pieces / 5 cm) as an average value when 5 samples are taken ² 10 μm or more and 20 or less is 10 (pieces / 5 cm) ² ), And 5 (between 5 μm and 10 μm) is 10 (pieces / 5 cm) ² ) The following high quality film 62 is produced.
[0064]
By the way, if a filtration process is continuously performed by the filter 30, the filter medium of the filter 30 will be obstruct | occluded gradually. Therefore, when the filter medium is blocked, the filter 29 that performs the filtering process is switched by the switch 29. And the filter 30 with which the filter medium was obstruct | occluded is wash | cleaned with the washing | cleaning apparatus shown in FIG. In FIG. 3, the cleaning device and the precoat tank 49 are connected to only one of the two filters 30, but the other filter 30 also has the same configuration of the cleaning device and the precoat. The tank is connected.
[0065]
The cleaning device has a cleaning solvent tank 38 and a discharge tank 40. The cleaning solvent tank 38 is connected to the dope discharge side 30 </ b> B of the filter 30 via the supply line 45, and is connected to the dope stock solution supply side 30 </ b> A of the filter 30 via the recovery line 46.
[0066]
A cleaning solvent is stored in the cleaning solvent tank 38. The cleaning solvent is not particularly limited as long as it can clean the filter medium of the filter 30, but the solvent type is preferably at least one of the solvent types constituting the dope solvent, and constitutes a dope solution. It is preferable that all of the solvent species to be used are the same solvent species. Furthermore, it is preferable from the viewpoint of environmental protection that the organic solvent of the liquid to be used including the cleaning solvent is non-chlorine.
[0067]
The supply line 45 is provided with a pump 39 and a heater 47. The pump 39 is driven when a part (or all) of the dope stock solution in the filter 30 is discharged from the filter 30, whereby the cleaning solvent in the cleaning solvent tank 38 is supplied to the heater 47. As the heater 47, an in-line mixer such as a multi-tube heat exchanger or a static mixer is used, and the cleaning solvent is heated by the heater 47. The heating temperature is set to a temperature that is 20 ° C. lower than the boiling point of the cleaning solvent at normal pressure under conditions where the cleaning solvent does not boil. Thus, the cleaning effect of the filter 30 can be improved by heating the cleaning solvent and supplying it to the filter 30. In addition, you may make it raise the internal pressure of the filter 30 so that a washing | cleaning solvent may not boil.
[0068]
The cleaning solvent sent to the filter 30 passes through the filter medium in the direction opposite to the dope stock solution during the filtration process, and is recovered in the cleaning solvent tank 38 via the recovery line 46. As a result, the cleaning solvent is circulated and supplied to the filter 30, and the cake formed on the dope stock solution supply side of the filter medium is peeled off from the filter medium. The peeled cake is dissolved in the cleaning solvent to form a slurry, which is discharged from the filter 30. And when the density | concentration of this slurry reaches a target value, the discharge operation | work of a slurry is performed. That is, a part (or all) of the cleaning solvent tank 38 is discharged to the discharge tank 40 through the discharge line 43, and a new cleaning solvent is supplied to the cleaning solvent tank 38. The slurry concentration target value is 1 to 50 kg / m. ³ It is set in the range. When the concentration is higher than this concentration range, the particles of the slurry agglomerate, which causes a problem that the discharge line 43 and the recovery line 46 are clogged. On the other hand, when the concentration is low, there is a problem that the cake discharge efficiency is poor.
[0069]
The slurry discharged to the discharge tank 40 is sent to the separation device 44 and separated into a solvent and a filter aid. Then, the solvent is sent to the recycle solution tank 36 in FIG. 1 and reused for preparing the dope. The filter aid is sent to the firing device 48 and fired to regenerate the filter aid. At that time, the regeneration efficiency of the filter aid can be improved by baking at 400 ° C. or higher. The regenerated filter aid is returned to the filter aid tank 37 and reused. At that time, the regenerated filter aid may be used alone, but if mixed with an unused filter aid, the cost can be significantly reduced without reducing the effect of the filter aid. it can. The mixing ratio of the regenerated filter aid and the unused filter aid may be about 1: 1.
[0070]
The filter aid tank 37 is connected to a precoat tank 49 in addition to the body feed tank 28. The dope is supplied to the precoat tank 49, and a filter aid is added to the dope. The filter aid is stirred and dispersed by rotating the stirring blade 66, whereby a precoat liquid is produced. The precoat liquid is supplied to the filter 30 after the filter medium is washed to remove the cake layer. As a result, a precoat layer made of a filter aid is formed on the surface of the filter medium. When the precoat layer is formed on the surface of the filter medium in this way, the effect of the filter aid can be obtained even at the initial stage of the filtration treatment. The precoat layer has a thickness of 0.1 to 10 mm, or a mass of 0.1 to 5 kg / m. ² It is preferable that If the thickness and mass of the precoat layer are smaller than this range, the filtration accuracy is lowered at the initial stage of the filtration treatment. On the other hand, when the thickness and mass of the precoat layer are large, the resistance of the precoat layer is increased during the filtration treatment, and the filtration efficiency is lowered. Therefore, it is preferable to form the precoat layer with the thickness and mass within the above ranges. In addition, the pre-coating liquid has a terminal speed of the filter aid of 10 ^-4 It is preferably in the range of ˜1 cm / s. By setting the terminal speed of the filter aid within this range, the filter aid of the precoat liquid is uniformly settled to form a uniform precoat layer.
[0071]
After the precoat layer is formed, the filtration process is performed again. That is, the dope stock solution is supplied from the body feed tank 28 by switching the switch 29. The insoluble matter and the filter aid contained in the dope stock solution are deposited on the surface of the precoat layer, and a cake layer having voids is formed. Thereby, the stable filtration process can be performed with high filtration accuracy.
[0072]
Thus, since this Embodiment performs a filtration process using a filter aid, it can improve absolute filtration accuracy, without making the hole diameter of a filter medium small. Further, as an effect of using the filter aid, it is possible to perform a stable filtration treatment and extend the filtration life. Furthermore, when the filter medium of the filter 30 is washed, the washing solvent may be circulated in the system, so that the burden on the operator can be greatly reduced.
[0073]
【Example】
Filtration was performed using the dope formulation A under various filtration conditions, and the filtration was stopped when the differential pressure reached 1 MPa. As the dope formulation A, methyl acetate (SP: 9.6, 75% by weight), acetone (SP: 9.9, 12.5% by weight), methanol (SP: 14.5, 6.25% by weight), A mixed solvent composed of ethanol (SP: 12.7, 6.25% by weight) was mixed with cellulose triacetate (substitution degree 2.75, SP: 10.9) to a concentration of 19%.
(Example 1)
As a filter aid, SiO ₂ Composition 95%, average particle size 70 μm, particle size standard deviation 20 μm, bulk density 0.45 g / cm ³ I used one. 0.2% of this filter aid was added at 55 ° C. for body feed. For pre-coating, terminal speed 10 ^-3 A liquid for pre-coating of cm / s was prepared, and the thickness was 2 mm and 0.8 kg / m. ² A precoat layer was formed. Then, filtration was started at a filtration flow rate of 0.4 cm / hr and an initial pressure of 0.3 MPa, and filtration was performed until the final thickness of the cake layer was 40 mm. During the filtration treatment, the filtration temperature was 50 ° C. (boiling point 58 ° C.), and the dissolved gas saturation was 85%. After the filtration treatment, the amount of auxiliary in the dope was 10 / cc, and the amount of auxiliary after subsequent filtration with a filter having an average pore diameter of 0.01 mm was 0 / cc. Further, after completion of filtration, a cleaning solvent having the same composition as the dope formulation A was circulated at 50 ° C. The cake formed on the filter medium is made into a slurry in the cleaning solution and 10 kg / m. ³ Was discharged. The filtration life (filtration amount per unit area) obtained under these conditions was determined, and this was set to 1 and compared with the following examples. Moreover, the film was produced and evaluated regarding dope quality. As a result, the number of bright spot defects observed under crossed Nicols is 5 cm in the width direction. ² 20 μm or more (hereinafter referred to as (1)) as an average value when 5 samples of 5 samples were collected 0 pieces / 5 cm ² 9 μm to 10 μm to 20 μm (hereinafter indicated by (2)) ² 5 to 10 μm (hereinafter indicated by (3)) is 3/5 cm ² Met.
(Example 2)
Cellulose filter aid as filter aid, bulk density 0.1 g / cm ³ The initial pressure was 0.4 MPa. The other conditions were the same as in Example 1. As a result, the amount of auxiliary in the dope after filtration was 1 piece / cc and the filtration life was 0.8. Moreover, as a film evaluation, (1) 0 pieces / 5cm ² , ▲ 2 ▼ 5 / 5cm ² , (3) 1 piece / 5cm ² Met. Therefore, sufficient effects can be obtained even when a cellulose-based filter aid is used.
(Example 3)
Filtration was performed under the same conditions as in Example 1 using an auxiliary prepared by mixing 1: 1 the auxiliary used in Example 1 and the auxiliary used in Example 2. As a result, the amount of auxiliary in the dope after filtration was 3 / cc and the filtration life was 0.95. Moreover, as a film evaluation, (1) 0 pieces / 5cm ² , ▲ 2 ▼ 5 / 5cm ² , (3) 1 piece / 5cm ² Met. Therefore, cellulosic auxiliary and SiO ₂ It is understood that 50% or more of an auxiliary may be mixed.
Example 4
The auxiliary used in Example 1 was baked at 800 ° C. and filtered under the same conditions as in Example 1. As a result, the amount of auxiliary in the dope after filtration was 3 / cc and the filtration life was 0.98. Moreover, as a film evaluation, (1) 0 pieces / 5cm ² , ▲ 2 ▼ 10 / 5cm ² , ▲ 3 ▼ 4 / 5cm ² Met. Therefore, it can be seen that a sufficient effect can be obtained if the auxiliary is baked at 800 ° C. and regenerated.
(Example 5)
The auxiliary used in Example 1 was calcined at 800 ° C., mixed with an unused filter aid of the same type in a ratio of 1: 1, and filtered under the same conditions as in Example 1. As a result, the filtration life was 0.985. Moreover, as a film evaluation, (1) 0 pieces / 5cm ² , ▲ 2 ▼ 10 / 5cm ² , ▲ 3 ▼ 3 / 5cm ² Met.
(Comparative Example 1)
As a filter aid, SiO ₂ Filtration was performed under the same conditions as in Example 1 using a filter aid having a composition of 48%. As a result, the filtration life was as good as 0.98, but the film was evaluated as follows: (1) 1 piece / 5 cm ² , ▲ 2 ▼ 12 / 5cm ² , ▲ 3 ▼ 12 / 5cm ² As a result, sufficient quality could not be obtained. For this reason, SiO ₂ The composition is preferably 50% or more. (Comparative Example 2)
SiO having an average particle size of 155 μm as a filter aid ₂ The initial pressure was 0.2 MPa, and the others were filtered under the same conditions as in Example 1. As a result, the filtration life was as good as 1.2, but the evaluation of the film was (1) 4 pieces / 5 cm. ² , ▲ 2 ▼ 20 / 5cm ² , ▲ 3 ▼ 22 / 5cm ² As a result, sufficient quality could not be obtained. For this reason, it is preferable that the average particle diameter of a filter aid is 150 micrometers or less.
(Comparative Example 3)
SiO having an average particle size of 0.5 μm as a filter aid ₂ The initial pressure was 0.8 MPa, and the others were filtered under the same conditions as in Example 1. As a result, the filtration life was shortened to 0.5. For this reason, it is preferable that the average particle diameter of a filter aid is 1.0 micrometer or more. In addition, evaluation of film is (1) 0 piece / 5cm ² , ▲ 2 ▼ 2 / 5cm ² , ▲ 3 ▼ 2 / 5cm ² As a result, sufficient quality was obtained.
(Comparative Example 4)
SiO having a particle size standard deviation of 40 as a filter aid ₂ The initial pressure was 0.35 MPa, and the others were filtered under the same conditions as in Example 1. As a result, the amount of auxiliary agent in the dope after filtration was 100,000 / cc, the amount of auxiliary agent after filtering through the filter was 10 / cc, and the amount of auxiliary agent leaked was large. For this reason, it is preferable that the particle size standard deviation of the filter aid is ½ average particle size or less. The filtration life is 0.95 and the evaluation of the film is (1) 0 pieces / 5 cm. ² , ▲ 2 ▼ 5 / 5cm ² , ▲ 3 ▼ 2 / 5cm ² It was good.
(Comparative Example 5)
15% of the filter aid used in Example 1 was added. As a result, the amount of auxiliary agent in the dope after filtration was 20 / cc, and the amount of auxiliary agent leaked was slightly increased, but could be completely removed with a filter (0 / cc). However, the filtration life was as short as 0.1. For this reason, it is preferable that the addition amount of a filter aid is 10% or less. In addition, evaluation of film is (1) 0 piece / 5cm ² , ▲ 2 ▼ 5 / 5cm ² , ▲ 3 ▼ 2 / 5cm ² And good results were obtained.
(Comparative Example 6)
The amount of filter aid added in Example 1 was 0.005%. As a result, the filtration life was shortened to 0.5. For this reason, the addition amount of the filter aid is preferably 0.01% or more. In addition, the evaluation of the film is (1) 3 pieces / 5cm ² , ▲ 2 ▼ 10 / 5cm ² , ▲ 3 ▼ 8 / 5cm ² Met.
(Comparative Example 7)
Using the precoat solution used in Example 1, the thickness was 15 mm, 6 kg / m. ² A precoat layer was formed. Then, the initial pressure was 1 MPa, and other conditions were filtered under the same conditions as in Example 1. As a result, the filtration life was 0.1, which was greatly reduced. From this, it can be seen that when the thickness and mass of the precoat layer are increased, a problem occurs in terms of filtration life. For this reason, the precoat layer has a thickness of 10 mm or less and a mass of 5 kg / m. ² The following is preferable. In addition, evaluation of film is (1) 0 piece / 5cm ² , ▲ 2 ▼ 1 piece / 5cm ² , (3) 1 piece / 5cm ² It was good.
(Comparative Example 8)
Using the same filter aid as in Example 1, a precoat solution having an end speed of 2 cm / s for the filter aid was prepared, and the thickness was 0.1 to 3 mm and the mass was 0.8 kg / m. ² A precoat layer was formed. And it filtered on the same conditions as Example 1. FIG. As a result, the amount of leaking filter aid increased, and the amount of aid in the dope after filtration became very large, 100,000 pieces / cc. In addition, even when filtration was performed using a filter having an average pore diameter of 0.01 mm, 100 / cc of auxiliary agent remained. Moreover, the malfunction that a precoat layer became non-uniform | heterogenous thickness also generate | occur | produced. For this reason, the terminal speed of the filter aid is preferably 1 cm / s or less.
(Comparative Example 9)
Filtration was performed under the same conditions as in Example 1 except that the filtration flow rate was 51 cm / hr and the initial pressure was 1.5 MPa. As a result, the amount of leaking filter aid increases, the amount of aid in the dope after filtration becomes as large as 300,000 pieces / cc, and even when filtered using a filter having an average pore diameter of 0.01 mm. The auxiliary agent remained at 1000 pieces / cc. Moreover, the filtration life is very short with 0.05, and the evaluation of the film is (1) 10 pieces / 5 cm. ² , ▲ 2 ▼ 25 / 5cm ² , ▲ 3 ▼ 28 / 5cm ² And quality decline was seen. For this reason, the initial pressure is preferably 1 MPa or less and the filtration flow rate is preferably 50 cm / hr or less.
(Comparative Example 10)
The filtration temperature during the filtration treatment was 20 ° C. (boiling point 58 ° C.), and the dissolved gas saturation was 89%. The initial pressure was 0.5 MPa, and the others were filtered under the same conditions as in Example 1. As a result, the amount of auxiliary agent in the dope after filtration was 10 pieces / cc and the amount of auxiliary agent after filtration with a filter having an average pore diameter of 0.01 mm was 0 pieces / cc. It decreased to 7. Therefore, the filtration temperature is preferably heated to a value (38 ° C.) or higher that is 20 degrees lower than the boiling point of the cellulose acylate solution.
(Comparative Example 11)
The filtration temperature during the filtration treatment was 57 ° C. (boiling point 58 ° C.), and the dissolved gas saturation was 89%. Then, filtration was performed under the same conditions as in Example 1 except that the initial pressure was 0.5 MPa. As a result, the amount of leaking filter aid increases, the amount of aid in the dope after filtration becomes 100,000 pieces / cc, and the amount of aid after filtration with a filter having an average pore diameter of 0.01 mm is 1000 pieces / cc. It was. This shows that when the filtration temperature is high and the cellulose acylate solution partially boiled, the cake is destroyed and the filter aid leaks. Therefore, it is preferable that the filtration treatment is performed under a pressure condition that does not boil reliably. The filtration life is 1.01, and the evaluation of the film is (1) 0 pieces / 5 cm. ² , ▲ 2 ▼ 11 / 5cm ² , ▲ 3 ▼ 11 / 5cm ² Although it was slightly reduced, good results were obtained.
(Comparative Example 12)
A filter having an average pore diameter of 80 μm was used as the filter after filtration. And the dope whose auxiliary agent amount in the dope after filtration was 10 pieces / cc was filtered with the filter. As a result, the amount of auxiliary agent in the dope was 5 / cc, and the auxiliary agent leaked. For this reason, the filter after filtration preferably has a filter medium average pore diameter of 50 μm or smaller.
(Comparative Example 13)
A filter having an average pore diameter of 1 μm was used as a filter after filtration. As a result, the leaked filter aid could be completely collected by the filter, but the pressure immediately increased and the filter dope could not be obtained.
(Comparative Example 14)
70kg / m of cake as slurry at the time of washing treatment ³ Was discharged. As a result, the filter aid was agglomerated and settled in the piping, and the recovery rate of the aid was reduced to 98%.
(Comparative Example 15)
The filter aid used in Example 1 was baked at 300 ° C., and the same filtration experiment was performed again. As a result, the filtration life decreased to 0.8. Moreover, the evaluation of the film is (1) 3 pieces / 5cm ² , ▲ 2 ▼ 15 / 5cm ² , ▲ 3 ▼ 12 / 5cm ² The quality decreased slightly. For this reason, considering the regeneration rate of the filter aid, it is preferable to fire at a higher temperature, and it is preferable to fire at 400 ° C. or higher.
[0074]
Next, the dope formulation A was co-cast using a 17% dope having the same composition as a side stream to produce a triacetyl cellulose film having a thickness of 80 μm. Then, a hard coat layer coating solution was applied with a bar coater, dried at 120 ° C., and then an illuminance of 400 mW / cm using a 160 W / cm air-cooled metal halide lamp (manufactured by Eye Graphics Co., Ltd.). ² , Irradiation amount 300J / cm ² The coating layer was cured by irradiating the ultraviolet ray to form a hard coat layer having a thickness of 2.5 μm. An antiglare layer coating solution was applied thereon with a bar coater, dried and UV cured under the same conditions as the hard coat layer, to form an antiglare layer having a thickness of about 1.5 μm. On top of this, a coating solution for a low refractive index layer was applied with a bar coater, dried at 80 ° C., and then thermally crosslinked at 120 ° C. for 10 minutes to form a low refractive index layer having a thickness of 0.096 μm. The hard coat layer coating solution, the antiglare layer coating solution, and the low refractive index layer coating solution will be described at the end of the examples.
[0075]
The obtained film was evaluated for the following items.
(1) Specular reflectance and color
[0076]
A spectrophotometer V-550 (manufactured by JASCO Corporation) is equipped with an adapter ARV-474, and in the wavelength region of 380 to 780 nm, the specular reflectance at an incident angle of 5 ° at an incident angle of 5 ° is measured. An average reflectance of 450 to 650 nm was calculated, and antireflection properties were evaluated.
[0077]
Further, CIE 1976 L * a * b * color space L * value, a * value, and b * value representing the color of regular reflected light with respect to 5 ° incident light of CIE standard light source D65 are calculated from the measured reflection spectrum. The color of reflected light was evaluated.
(2) Integral reflectance
An adapter ILV-471 is attached to a spectrophotometer V-550 (manufactured by JASCO Corporation), and an integrated reflectance at an incident angle of 5 ° is measured in a wavelength region of 380 to 780 nm, and an average reflection of 450 to 650 nm. The rate was calculated.
(3) Haze
The haze of the obtained film was measured using a haze meter MODEL 1001DP (manufactured by Nippon Denshoku Industries Co., Ltd.).
(4) Pencil hardness evaluation
The pencil hardness evaluation described in JIS K 5400 was performed as an index of scratch resistance. After conditioning the antireflection film at a temperature of 25 ° C. and a humidity of 60% RH for 2 hours, using a 3H test pencil specified in JIS S 6006, with a load of 1 kg,
No scratch is observed in the evaluation of n = 5: ○
In evaluation of n = 5, 1 or 2 scratches:
In evaluation of n = 5, 3 or more scratches: ×
(5) Contact angle measurement
As an index of surface contamination resistance, the optical material was conditioned at a temperature of 25 ° C. and a humidity of 60% RH for 2 hours, and then the contact angle with water was measured to obtain an index of fingerprint adhesion.
(6) Dynamic friction coefficient measurement
The dynamic friction coefficient was evaluated as an index of surface slipperiness. As the dynamic friction coefficient, a sample was conditioned at 25 ° C. and a relative humidity of 60% for 2 hours, and then a value measured with a HEIDON-14 dynamic friction measuring machine at a 5 mmφ stainless steel ball, a load of 100 g, and a speed of 60 cm / min was used.
(7) Anti-glare evaluation
Bare fluorescent light (8000 cd / m) without louver on the antiglare film produced ² ) And the degree of blur of the reflected image was evaluated according to the following criteria.
[0078]
I do not know the outline of the fluorescent lamp at all: ◎
The outline of the fluorescent lamp changes slightly: ○
The fluorescent light is blurred, but the outline can be identified:
Fluorescent lamp is hardly blurred: ×
Table 1 shows the results of evaluation based on the above items. As shown in the table, the obtained film is excellent in antiglare property and antireflection property and has a weak color, and the evaluation reflects film properties such as pencil hardness, fingerprint adhesion, and dynamic friction coefficient. The result was also good.
[0079]
[Table 1]

Next, an antiglare antireflection polarizing plate was prepared using the obtained film. Using this polarizing plate, a liquid crystal display device in which an antireflection layer was disposed on the outermost layer was produced. As a result, excellent contrast was obtained because there was no reflection of external light, and the reflection image was not noticeable due to antiglare properties. Visibility was good, and fingerprinting was good.
(Preparation of antiglare layer coating solution)
439 g of methyl ethyl ketone from 125 g of a mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate (DPHA, manufactured by Nippon Explosives Co., Ltd.) and 125 g of bis (4-methacryloylthiophenyl) sulfide (MPSMA, manufactured by Sumitomo Seika Co., Ltd.) / Cyclohexanone = dissolved in a mixed solvent of 50/50% by weight. A solution prepared by dissolving 5.0 g of a photopolymerization initiator (Irgacure 907, manufactured by Ciba Geigy) and 3.0 g of a photosensitizer (Kayacure DETX, manufactured by Nippon Explosives Co., Ltd.) in 49 g of methyl ethyl ketone was added to the obtained solution. The refractive index of the coating film obtained by applying this solution and curing with ultraviolet rays was 1.60.
[0080]
Further, 10 g of a crosslinked polystyrene particle having an average particle diameter of 2 μm (trade name: SX-200H, manufactured by Soken Chemical Co., Ltd.) was added to this solution, and the mixture was stirred and dispersed at 5000 rpm for 1 hour with a high speed dispaper. An antiglare layer coating solution was prepared by filtration through a polypropylene filter.
(Preparation of coating solution for hard coat layer)
A solution prepared by dissolving 250 g of an ultraviolet curable hard coat composition (Desolite KZ-7687, 72 wt%, manufactured by JSR Corporation) in 62 g of methyl ethyl ketone and 88 g of cyclohexanone was added. The refractive index of the coating film obtained by applying this solution and curing with ultraviolet rays was 1.53.
[0081]
Furthermore, this solution was filtered through a polypropylene filter having a pore diameter of 30 μm to prepare a coating solution for a hard coat layer.
(Preparation of coating solution for low refractive index layer)
MEK-ST (average particle size of 10 to 20 nm, solid content concentration of 30% by weight of SiO2) was added to 20093 g of a heat-crosslinkable fluorine-containing polymer (TN-049, manufactured by JSR Corporation) with a refractive index of 1.42. ₂ 8 g of a sol MEK dispersion (manufactured by Nissan Chemical Co., Ltd.) and 100 g of ruethyl ketone were added. After stirring, the solution was filtered through a polypropylene filter having a pore size of 1 μm to prepare a coating solution for a low refractive index layer.
[0082]
【The invention's effect】
As described above, according to the solution casting method according to the present invention, since the cellulose acylate solution is filtered using the filter aid, clogging of the filter medium can be suppressed and the filter life can be extended. At the same time, the filtration accuracy can be improved.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a dope production line to which a filter cleaning method according to the present invention is applied.
FIG. 2 is a configuration diagram of a film forming apparatus.
FIG. 3 is a configuration diagram of a filter cleaning device according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Dope production line, 11 ... Solvent tank, 12 ... Dissolution tank, 14 ... Metering device, 15 ... Plasticizer tank, 20 ... Storage tank, 27 ... Pump, 28 ... Body feed tank, 29 ... Switch, 30 ... Filtration machine 31 ... Flow meter, 32 ... Dope, 33 ... Dope tank, 34 ... Cleaning solvent recovery tank, 36 ... Recycle solution tank, 37 ... Filter aid tank, 38 ... Cleaning solvent tank, 39 ... Pump, 40 ... Discharge tank, 41 ... stirring blade, 42 ... filter member, 43 ... discharge line, 44 ... separation device, 46 ... collection line, 47 ... heater, 48 ... baking device, 49 ... tank for precoat, 50 ... film forming device , 51 ... Band zone, 52 ... Drying zone, 54 ... Filter, 59 ... Casting band, 60 ... Casting die, 61 ... Stripping roller, 62 ... Film, 63 ... Ten

Claims (36)

In a solution casting method for producing a cellulose acylate film by preparing a cellulose acylate solution and filtering,
A solution casting method characterized by using a filter aid for the filtration treatment. _2. The solution casting method according to claim 1, wherein 50% or more of the composition of the filter aid is SiO2. 2. The solution casting method according to claim 1, wherein the filter aid is a cellulosic aid. _2. The solution casting method according to claim 1, wherein the filter aid is a mixture of a cellulosic aid and an aid containing 50% or more of SiO2. The solution casting method according to claim 1, wherein the filter aid is composed of a mixture of two or more. 6. The solution casting method according to claim 1, wherein the filter aid has an average particle diameter of 1 to 150 [mu] m. The solution casting method according to any one of claims 1 to 6, wherein the filter aid has a standard deviation in particle size of ½ average particle size or less. The solution casting method according to claim 1, wherein a bulk density of the filter aid is 0.01 to 0.8 g / cm ³ . The filter aid was added in an amount of 0.01 to 10 wt. The solution casting method according to claim 1, wherein% is added. The solution casting method according to any one of claims 1 to 9, wherein the pre-coating liquid in which the filter aid is dispersed is pre-coated at 0.1 to 10 mm on a filtration support. The solution according to any one of claims 1 to 10, wherein a precoat liquid in which the filter aid is dispersed is precoated at 0.1 to 5 kg / m ² on a filter support. Membrane method. The solution casting method according to claim 10 or 11, wherein the precoat liquid has an end speed of the filter aid of ^{10-4 to 1} cm / s. The solution casting method according to any one of claims 1 to 12, wherein the filtration treatment has a filtration flow rate of 0.1 to 50 cm / hr. The solution casting method according to claim 1, wherein the filtration treatment has an initial differential pressure of 0.01 to 1 MPa. The solution casting method according to claim 1, wherein the filtration treatment has a filtration pressure of 0.01 to 4 MPa. The solution casting method according to claim 1, wherein the filtration treatment has a filtration differential pressure of 0.01 to 3 MPa. The solution casting method according to any one of claims 1 to 16, wherein the filtration treatment has a cake layer thickness of 0.1 to 80 mm. The filtration process is performed under a pressure condition in which the cellulose acylate solution does not boil and at a temperature of 20 ° C. lower than the boiling point of the cellulose acylate solution at normal pressure. The solution casting method described. The filter aid is dispersed in the cellulose acylate solution in a range between the boiling point of the cellulose acylate solution at normal pressure and a temperature lower than the boiling point by 20 ° C., and dissolved bubbles in the cellulose acylate solution The solution casting method according to any one of claims 1 to 18, wherein the filtration treatment is performed after saturation reaches 90% or less. 20. The solution casting method according to claim 1, wherein the filtration treatment is performed at a temperature lower than when the filter aid is dispersed in the cellulose acylate solution. The solution casting method according to any one of claims 1 to 20, wherein the concentration of the filter aid in the cellulose acylate solution after the filtration treatment is 10,000 pieces / cc or less. The solution casting method according to any one of claims 1 to 21, wherein the cellulose acylate solution after the filtration treatment is subjected to subsequent filtration treatment with a filter having an absolute filtration accuracy of 2 to 50 µm. The filter that has been subjected to the filtration treatment is back-washed with a washing solvent, and the washing solvent is circulated and supplied under pressure conditions that do not boil and heated to a temperature that is 20 ° C. lower than the boiling point of the cellulose acylate solution. The solution casting method according to any one of claims 1 to 22, The solution casting method according to any one of claims 1 to 23, wherein the cake formed on the filtration support by the filtration treatment is discharged as a slurry having a concentration range of 1 to 50 kg / m ^3. . The solution casting method according to claim 24, wherein the slurry is reused as a precoat liquid or a body feed liquid. The solution casting method according to claim 23, wherein the organic solvent used is a non-chlorine solvent. The solution casting method according to claim 24, wherein the discharged cake slurry is separated into a solvent and the filter aid, and then the filter aid is baked at 400 ° C or higher and reused. . 28. The solution casting method according to claim 27, wherein the regenerated filter aid is mixed with an unused filter aid. 29. The solution casting method according to claim 1, wherein the filtered cellulose acylate solution is formed by co-casting. A cellulose acylate film produced by the solution casting method according to claim 1. A cellulose acylate film according to claim 30, or 20μm average value when the number of bright point defects observed were collected 5 points a sample of 5 cm ² in the width direction under crossed nicols 0 / A cellulose acylate film having a size of 5 cm ² , 10 μm or more is 10 pieces / 5 cm ² or less, and 5 μm or more is 10 pieces / 5 cm ² or less. A polarizing plate comprising the cellulose acylate film according to claim 30 or 31 as a protective film. An optical compensation film comprising the cellulose acylate film according to claim 30 or 31. A liquid crystal display device using the polarizing plate according to claim 32. A liquid crystal display device comprising the optical compensation film according to claim 33. A photographic light-sensitive material comprising the cellulose acylate film according to claim 30 or 31.

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