JP2006188048A - Method and apparatus for producing film from solution - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the foaming of a solvent in a cast film, the remainder of the cast film when the film is stripped, and biting/tearing when the cast film is held and conveyed. <P>SOLUTION: A drying casing 84 is set above a casting band 72 to surround the cast film 80, and hot air for drying the cast film 80 is circulated. A pair of windshields 130 and 132 facing each other in the width direction of the cast film 80 is set in the casing 84. In the windshields 130 and 132, the side parts 130b and 132b opposite to the side parts 130a and 132a on the cast film 80 side are held rotatably, and by changing the width W1 between the side parts 130a and 132a by rotation, the blast range of the hot air is changed. The windshields 130 and 132 are driven by a transfer mechanism 138 and moved corresponding to the width of the cast film 80. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  In the present invention, a polymer is dissolved in a solvent to form a dope, and the dope is cast on a moving support to form a cast film, and then dried by sending dry air to the cast film. The present invention relates to a solution casting apparatus and method for producing a film by peeling a cast film from the support.

  As a method for forming an optical polymer film such as a cellulose acylate film, a solution film forming method is known. In the solution casting method, a polymer material is dissolved with a solvent to form a dope, and then the dope is cast from a die onto a metal support such as a rotating band or drum to generate a casting film. And it dries by sending dry air (hot air) to the casting film on a metal support body, and a belt-like film is obtained by peeling when the casting film has self-supporting property.

However, since the metal support is formed wider than the cast film, the drying air hits the metal support exposed to the outside of both sides of the cast film and heats it. And there existed a malfunction that the temperature of the both sides of a casting film became high under the influence of this heat, and the solvent in a casting film would foam. For this reason, the following Patent Document 1 describes a method for producing a film in which wind shielding plates are provided in the vicinity of both sides of a cast film so that dry air does not hit the metal support.
JP 61-110520 A

  By the way, the width of the casting film varies from production rod to production rod due to differences in various conditions such as the type of film to be formed, the composition of the dope, the temperature and humidity during casting. However, in the method described in the above-mentioned patent document, since the wind shielding member is a fixed type, when the width of the casting film changes, the drying air is blown to an appropriate range corresponding to the width of the casting film. I could not.

  For this reason, when the width of the casting film is narrower than the width of the windshield member, as described above, the metal support is heated, the temperature of both sides of the casting film becomes high, and the solvent in the casting film Will foam. Further, when the width of the casting film is wider than the width of the wind shielding member, the drying air is not blown to both sides of the casting film, resulting in insufficient drying, and when the casting film is peeled off This has been a problem in that peeling off occurs on the surface, and biting and tearing occurs when the film after peeling is gripped and conveyed.

  The present invention has been made in view of the above background, and even if the width of the cast film changes, the foaming of the solvent in the cast film, the remaining unstriped when the cast film is peeled off, and gripped. An object of the present invention is to provide a solution casting apparatus and method capable of preventing problems such as biting and tearing during conveyance.

  In order to achieve the above object, the solution casting apparatus of the present invention is provided with a pair of wind shielding members facing each other in the width direction of the casting film, and by sending dry air between these wind shielding members, In addition to restricting the blowing range of the dry wind in the width direction, a wind shield member moving mechanism is provided that moves the wind shield member to change the width of the wind shield member, and the wind shield member is arranged according to the width of the casting film. It is made to move and adjust the ventilation range of dry wind.

  In addition, the solution casting method of the present invention regulates the blowing air blowing range in the width direction of the casting membrane by sending the drying air between a pair of wind shielding members facing each other in the width direction of the casting membrane. The wind-shielding member is moved according to the width of the casting film, and the width of the wind-shielding member is changed to adjust the blowing air blowing range.

  The wind-shielding member may be formed long in the casting direction of the casting film, or may be arranged side by side along the casting direction of the casting film.

  The wind-shielding member is preferably moved so that the width is greater than 0.8 times and less than 1.2 times the width of the cast film. In particular, the width of the wind shielding member is preferably 0.9 times or more and 1.1 times or less of the width of the casting film. Moreover, it is preferable that the clearance gap between a wind-shielding member and a casting film shall be 5 mm or more and 30 mm or less. In particular, the gap between the wind shielding member and the cast film is preferably 18 mm or more and 20 mm or less.

  Further, the wind shield member is provided so as to be rotatable around the rear end side opposite to the tip side on the casting membrane side, and the wind shield member is rotated to change the width of the tip side to dry the wind shield member. You may adjust the ventilation area of a wind.

  When the wind shield member is rotated, the angle formed with the casting film is in the range of 45 ° or more and 90 ° or less, and the front end side is wider than the rear end side. It is preferable to move it. Further, the wind shield member is provided so as to be stretchable in a direction connecting the front end side and the rear end side, and the wind shield member is expanded and contracted with rotation to change the length from the front end side to the rear end side. It is preferable to adjust the gap between the cast film and the wind shielding member.

In addition, the present invention preferably satisfies the following.
(1) The weight (residual solvent amount) of the residual solvent in the cast film at the time of peeling is 100% to 400% of the weight of the film.
(2) At the time of stripping, the amount of residual solvent on both sides in the width direction of the cast film is greater than 0.9 times and less than 1.1 times the amount of residual solvent in the center portion in the width direction.
(3) When producing the dope, a non-chlorine organic solvent is used as the main solvent.
(4) The dope is divided into at least two parts, one is used as a lower layer on the support side and the other is used as an upper layer, and the dope casted on the support side is promoted to peel off from the support. Add stripping accelerator.
(5) In the film, the plasticizer is 3% to 20% by weight, the ultraviolet absorber is 0.001% to 5% by weight, and the fine particle powder is 0.001% to 5% by weight with respect to the polymer. included.

  According to the present invention, a wind shield member is provided so that hot air does not hit the metal support, and the wind shield member is movable so that the blowing range of the dry wind is adjusted according to the width of the casting film. did. For this reason, even if the width of the casting film changes, the drying air can be blown to an appropriate range corresponding to the width of the casting film. Can prevent problems such as tearing

[material]
As the cellulose acylate, it is preferable to use cellulose acylate (hereinafter referred to as TAC) in which the substitution degree of the hydroxyl group of cellulose satisfies all of the following formulas (1) to (3).
(1) 2.5 ≦ A + B ≦ 3.0
(2) 0 ≦ A ≦ 3.0
(3) 0 ≦ B ≦ 2.9
In the formula, A and B represent the substitution degree of the acyl group substituted with the hydroxyl group of cellulose, A is the substitution degree of the acetyl group, and B is the substitution degree of the acyl group having 3 to 22 carbon atoms. . In addition, it is preferable to use particles having 90% by mass or more of TAC of 0.1 mm to 4 mm.

  Glucose units having β-1,4 bonds constituting cellulose have free hydroxyl groups at the 2nd, 3rd and 6th positions. Cellulose acylate is a polymer obtained by esterifying some or all of these hydroxyl groups with an acyl group having 2 or more carbon atoms. The degree of acyl substitution means the ratio at which the hydroxyl group of cellulose is esterified at each of the 2-position, 3-position and 6-position (100% esterification has a substitution degree of 1).

  The total acyl substitution degree, that is, DS2 + DS3 + DS6 is preferably 2.00 to 3.00, more preferably 2.22 to 2.90, and particularly preferably 2.40 to 2.88. Further, D6S / (DS2 + DS3 + DS6) is preferably 0.28 or more, more preferably 0.30 or more, and particularly preferably 0.31 to 0.34. Here, DS2 is the degree of substitution of the hydroxyl group at the 2-position of the glucose unit with an acyl group (hereinafter also referred to as “degree of acyl substitution at the 2-position”), and DS3 is the degree of substitution of the hydroxyl group at the 3-position with an acyl group (hereinafter, referred to as “acyl group”). DS6 is the substitution degree of the hydroxyl group at the 6-position with an acyl group (hereinafter also referred to as “acyl substitution degree at the 6-position”).

  Only one type of acyl group may be used in the cellulose acylate of the present invention, or two or more types of acyl groups may be used. When two or more types of acyl groups are used, one of them is preferably an acetyl group. DSA + DSB, where DSA is the total substitution degree of hydroxyl groups at the 2nd, 3rd and 6th positions with acetyl groups, and DSB is the total substitution degree with hydroxyl groups other than the acetyl groups at the 2nd, 3rd and 6th hydroxyl groups The value of is preferably 2.22 to 2.90, more preferably 2.40 to 2.88. The DSB is preferably 0.30 or more, particularly preferably 0.7 or more. Further, 20% or more of DSB is preferably a substituent at the 6-position hydroxyl group, more preferably 25% or more is a substituent at the 6-position hydroxyl group, more preferably 30% or more, and particularly 33% or more is 6%. A substituent of a hydroxyl group is preferred. The cellulose acylate preferably has a substitution degree value at the 6-position of 0.75 or more, more preferably 0.80 or more, and particularly preferably 0.85 or more. . With these cellulose acylates, a solution having a preferable solubility (dope) can be produced. In particular, in a non-chlorine organic solvent, a good solution can be produced. Furthermore, a solution having a low viscosity and good filterability can be produced.

  The cellulose acylate may be obtained from either linter cotton or pulp cotton, but is preferably obtained from linter cotton.

  The acyl group having 2 or more carbon atoms of the cellulose acylate of the present invention may be an aliphatic group or an aryl group and is not particularly limited. These are, for example, cellulose alkylcarbonyl esters, alkenylcarbonyl esters, aromatic carbonyl esters, aromatic alkylcarbonyl esters, and the like, each of which may further have a substituted group. Preferred examples of these include propionyl group, butanoyl group, pentanoyl group, hexanoyl group, octanoyl group, decanoyl group, dodecanoyl group, tridecanoyl group, tetradecanoyl group, hexadecanoyl group, octadecanoyl group, iso-butanoyl group , T-butanoyl group, cyclohexanecarbonyl group, oleoyl group, benzoyl group, naphthylcarbonyl group, cinnamoyl group and the like. Among these, a propionyl group, a butanoyl group, a dodecanoyl group, an octadecanoyl group, a t-butanoyl group, an oleoyl group, a benzoyl group, a naphthylcarbonyl group, a cinnamoyl group, and the like are more preferable, and a propionyl group and a butanoyl group are particularly preferable. is there.

  Solvents for preparing the dope include aromatic hydrocarbons (eg, benzene, toluene, etc.), halogenated hydrocarbons (eg, dichloromethane, chlorobenzene, etc.), alcohols (eg, methanol, ethanol, n-propanol, n-butanol, Diethylene glycol, etc.), ketones (eg, acetone, methyl ethyl ketone, etc.), esters (eg, methyl acetate, ethyl acetate, propyl acetate, etc.) and ethers (eg, tetrahydrofuran, methyl cellosolve, etc.).

  A halogenated hydrocarbon having 1 to 7 carbon atoms and dichloromethane are preferably used. From the viewpoint of physical properties such as solubility of TAC, peelability of cast film from the support, mechanical strength of the film, and optical properties of the film, in addition to dichloromethane, one or more alcohols having 1 to 5 carbon atoms are used. It is preferable to mix several types. 2 mass%-25 mass% are preferable with respect to the whole solvent, and, as for content of alcohol, 5 mass%-20 mass% are more preferable. Examples of the alcohol include methanol, ethanol, n-propanol, isopropanol, and n-butanol.

  Recently, a solvent composition not using dichloromethane has been proposed in order to minimize the influence on the environment. For this purpose, ethers having 4 to 12 carbon atoms, ketones having 3 to 12 carbon atoms, and esters having 3 to 12 carbon atoms are preferable, and these are used by being appropriately mixed. These ethers, ketones and esters may have a cyclic structure. A compound having two or more functional groups of ether, ketone and ester (that is, —O—, —CO— and —COO—) can also be used as a solvent. The solvent may have another functional group such as an alcoholic hydroxyl group. In the case of a solvent having two or more kinds of functional groups, the number of carbon atoms may be within the specified range of the compound having any functional group.

  Any of the above can be used as the solvent, and a combination of these may be used as the solvent, but it is preferable to use a non-chlorine organic solvent such as ethyl acetate as the main solvent. The details of cellulose acylate are described in paragraphs [0140] to [0195] of JP-A-2005-104148, and these descriptions can also be applied to the present invention. Further, additives such as solvents and plasticizers, deterioration inhibitors, ultraviolet absorbers, optical anisotropy control agents, dyes, matting agents, release agents, and the like, from paragraph [0196] of JP 2005-104148 A to [0536]. ] Is described in detail in the paragraph.

[Production of raw material dope]
FIG. 1 shows a raw material dope production line 10. In manufacturing the raw material dope, first, the valve 12 is opened from the solvent tank 11, and the solvent is sent to the dissolution tank 13. Next, the TAC contained in the hopper 14 is fed into the dissolution tank 13 while being measured. The additive solution is sent from the additive tank 15 to the dissolution tank 13 by opening and closing the valve 16. In addition to the method of sending the additive as a solution, for example, when the additive is liquid at room temperature, it is also possible to send the additive to the dissolution tank 13 in the liquid state. In addition, when the additive is solid, it can be fed into the dissolution tank 13 using a hopper. When a plurality of types of additives are added, a solution in which a plurality of types of additives are dissolved can be placed in the additive tank 15. Alternatively, a solution in which an additive is dissolved can be put in each of a plurality of additive tanks and sent to the dissolution tank 13 through independent pipes.

  In the above description, the order of putting into the dissolution tank 13 is the solvent (used in the meaning including the case of the mixed solvent), TAC, and additive, but it is not limited to this order. It is also possible to send a preferable amount of the solvent after sending the TAC to the dissolution tank 13 while measuring it. Further, the additive does not necessarily need to be put in the dissolution tank 13 in advance, and can be mixed in a mixture of TAC and a solvent in a later step.

  A jacket 17 is provided so as to enclose the dissolution tank 13. A first stirring blade 19 that is rotated by a motor 18 is attached. Furthermore, it is preferable that the 2nd stirring blade 21 rotated by the motor 20 is attached. The first stirring blade 19 is preferably an anchor blade, and the second stirring blade 21 is preferably a dissolver type eccentric stirring machine. It is preferable to flow the heat transfer medium through the jacket 17 and adjust the temperature in the dissolution tank 13 in the range of −10 ° C. to 55 ° C. By appropriately selecting and rotating the first stirring blade 19 and the second stirring blade 21, the swelling liquid 22 in which the TAC is swollen in the solvent can be obtained.

  The swelling liquid 22 is sent to the heating device 26 by the pump 25. The heating device 26 preferably uses a jacketed pipe, and preferably has a configuration capable of pressurizing the swelling liquid 22. A raw material dope is obtained by dissolving TAC or the like in a solvent under heating or pressure heating conditions of the swelling liquid 22. In this case, the temperature of the swelling liquid 22 is preferably 0 ° C to 97 ° C. In addition, the cooling dissolution method which cools the swelling liquid 22 to the temperature of -150 degreeC--10 degreeC can also be performed. TAC can be sufficiently dissolved in a solvent by appropriately selecting the heating dissolution method and the cooling dissolution method. After the temperature of the raw material dope is set to about room temperature by the temperature controller 27, filtration by the filtering device 28 is performed to remove impurities in the raw material dope. The average pore diameter of the filtration filter of the filtration device 28 is preferably 100 μm or less. The filtration flow rate is preferably 50 L / hour or more. The raw material dope after filtration is put into the stock tank 30 through the valve 29.

  The raw material dope can be used as a solution film-forming dope described later. However, the method of dissolving TAC after preparing the swelling liquid 22 takes time as the concentration of TAC is increased, and may cause a problem in terms of cost. In that case, it is preferable to carry out a concentration step of preparing a raw material dope having a target concentration after preparing a raw material dope having a concentration lower than the target TAC concentration. The raw material dope filtered by the filtering device 28 is sent to the flash device 31 through the valve 29. A part of the solvent in the raw material dope is evaporated in the flash device 31. The evaporated solvent is made liquid by a condenser (not shown), and then recovered by the recovery device 32. It is advantageous from the viewpoint of cost that the solvent is regenerated and reused as a solvent for preparing the raw material dope by the regenerator 33.

  The concentrated raw material dope 36 is extracted from the flash unit 31 using the pump 34. Furthermore, it is preferable to remove bubbles in the raw material dope. Defoaming may be performed by any known method, for example, an ultrasonic irradiation method. Thereafter, the liquid is fed to the filtration device 35 to remove foreign matters. At this time, the temperature of the raw material dope 36 is preferably 0 ° C. to 200 ° C. Thus, the raw material dope 36 having a TAC concentration of 5% by mass to 40% by mass can be manufactured. The produced raw material dope 36 is stored in the stock tank 30.

  Regarding the raw material, raw material, additive dissolution method, filtration method, defoaming, and addition method in the solution casting method for obtaining a TAC film, refer to [0517] paragraph to [0616] paragraph of JP-A-2005-104148. These are described in detail and can be applied to the present invention.

[Solution casting method]
FIG. 2 shows a film production line 40. A stirring blade 42 that is rotated by a motor 41 is attached to the stock tank 30. The material dope 36 is always made uniform by rotating the stirring blade 42. Connected to the stock tank 30 are an intermediate layer dope channel 43, a support surface dope channel 44, and an air surface dope channel 45. The raw material dope 36 is fed by pumps 46, 47, 48 provided in the respective flow paths 43, 44, 45. After being fed to the feed block 70 and merged, it is cast from the casting die 71 onto the casting band 72.

[Dope manufacturing process]
The intermediate layer additive 51 contained in the stack tank 50 is fed to the raw material dope (hereinafter referred to as intermediate layer raw material dope) 36 in the intermediate layer dope channel 43 by the pump 52 and mixed. . Thereafter, the mixture is stirred and mixed by a static mixer (static mixer) 53 to be uniform. Thereby, the dope for the intermediate layer is generated. In the intermediate layer additive 51, for example, a solution (or dispersion) containing additives such as an ultraviolet absorber and a retardation control agent in advance is placed.

  The support surface additive 56 contained in the stock tank 55 is fed to the raw material dope (hereinafter referred to as “support surface raw material dope”) 36 in the support surface dope channel 44 by a pump 57 and mixed. . Thereafter, the mixture is stirred and mixed by the static mixer 58 to be uniform. Thereby, the dope for the support surface is generated. The support surface additive 56 includes a peeling accelerator (for example, citrate ester) that facilitates peeling from the casting band 72 as a support, and between the film surfaces when the film is wound into a roll. Additives such as a matting agent (for example, a fine particle powder such as silicon dioxide) that suppresses the adhesion of the resin are contained in advance. The support surface additive 56 may contain additives such as a plasticizer and an ultraviolet absorber.

  The air surface additive 61 contained in the stock tank 60 is fed to the raw material dope (hereinafter referred to as air surface raw material dope) 36 in the air surface dope channel 45 by the pump 62 and mixed. . Thereafter, the mixture is stirred and mixed by the static mixer 63 to be uniform. Thereby, the dope for air surfaces is produced | generated. The air surface additive 61 contains an additive such as a matting agent (for example, fine particle powder such as silicon dioxide) that suppresses adhesion between the film surfaces when the film is wound into a roll. Yes. The air surface additive 61 may contain additives such as a peeling accelerator, a plasticizer, and an ultraviolet absorber.

  Each dope generated by adding various additives to each raw material dope is fed to the feed block 70 at a desired flow rate. After the dopes merge in the feed block 70, they are cast from the casting die 71 onto the casting band 72.

[Casting process]
The material of the casting die 71 is preferably a double layer stainless steel. It is preferable to use a material having a thermal expansion coefficient of 2 × 10 ⁻⁵ (° C. ⁻¹ ) or less. Moreover, what has corrosion resistance substantially equivalent to SUS316 in the forced corrosion test in electrolyte aqueous solution can also be used. Further, a material having corrosion resistance that does not cause pitting (opening) at the gas-liquid interface even when immersed in a mixed solution of dichloromethane, methanol, and water for 3 months is used. And it is preferable to produce the casting die 71 by grinding a material that has passed one month or more after casting. Thereby, the surface shape of the dope flowing in the casting die 71 is kept constant. It is preferable to use a finishing accuracy of the wetted surfaces of the casting die 71 and the feed block 70 in terms of surface roughness of 1 μm or less and straightness of 1 μm / m or less in any direction. The slit clearance that can be adjusted in the range of 0.5 mm to 3.5 mm by automatic adjustment is used. About the corner | angular part of the liquid-contacting part of the lip | tip end of the casting die 71, R uses 50 micrometers or less over the full width of a slit. In addition, it is preferable to use what is adjusted so that the shear rate in the casting die 71 may be 1 (1 / second) to 5000 (1 / second).

  The width of the casting die 71 is not particularly limited, but it is preferable to use a casting die having a width of about 1.0 to 2.0 times the width of the final film. Further, during film formation, it is preferable to attach a temperature controller so as to be maintained at a predetermined temperature. The casting die 71 is preferably a coat hanger type. Furthermore, it is more preferable to provide a thickness adjusting bolt (heat bolt) at a predetermined interval and attach an automatic thickness adjusting mechanism using a heat bolt. It is preferable that the heat bolt is subjected to film formation by setting a profile according to the amount of pump 46 (preferably high precision gear pump) 46 to 48 according to a preset program. Further, feedback control may be performed by an adjustment program based on a profile of a thickness meter (for example, an infrared thickness meter) (not shown) in the film forming line 40. It is preferable that the thickness difference between any two points except the casting edge is adjusted within 1 μm, and the maximum difference in the width direction thickness is adjusted to 3 μm or less. In addition, it is preferable to use the one whose thickness accuracy is adjusted to ± 1.5 μm or less.

More preferably, a cured film is formed at the tip of the lip. A method for forming the cured film is not particularly limited, and examples thereof include ceramic coating, hard chrome plating, and a nitriding method. In the case of using ceramics as the cured film, it is preferable to use ceramics that can be ground, have low porosity, are not brittle, have good corrosion resistance, and have no adhesion to the casting die 71. Specific examples include tungsten carbide (WC), Al ₂ O ₃ , TiN, Cr ₂ O _{3 and the} like, but it is particularly preferable to use WC. The WC coating can be performed by a thermal spraying method.

  In order to prevent the dope flowing out to the slit end of the casting die 71 from locally drying and solidifying, it is preferable to attach a solvent supply device (not shown) to the slit end. Supplying a solvent for solubilizing the dope (for example, a mixed solvent of 86.5 parts by mass of dichloromethane, 13 parts by mass of acetone, and 0.5 parts by mass of n-butanol) to the gas-liquid interface between the end of the casting bead and the slit. Is preferred. In addition, it is preferable to use a pump having a pulsation rate of 5% or less for supplying the liquid.

  Below the casting die 71, a casting band 72 is provided as a support for casting the dope and is stretched around rotating rollers 73 and 74. The casting band 72 travels endlessly as the rotating rollers 73 and 74 are rotated by a driving device (not shown). The moving speed of the casting band 72, that is, the casting speed is preferably 10 m / min to 200 m / min. In order to make the surface temperature of the casting band 72 a predetermined value, it is preferable that a heat transfer medium circulation device 75 is attached to the rotary rollers 73 and 74. The surface temperature of the casting band 72 is preferably −20 ° C. to 40 ° C. A heat transfer medium flow path is formed in the rotation rollers 73 and 74, and the temperature of the rotation rollers 73 and 74 is set to a predetermined value by passing through the heat transfer medium maintained at a predetermined temperature. Can hold.

  The width of the casting band 72 is not particularly limited, but it is preferable to use one having a range of 1.1 to 3.0 times the casting width of the dope. Moreover, it is preferable to use what was polished so that length may be 10 m-200 m, thickness may be 0.3 mm-10 mm, and surface roughness may be 0.05 micrometer or less. The material is made of metal, particularly stainless steel, and more preferably SUS316 so as to have sufficient corrosion resistance and strength. In addition, it is preferable to use a thickness unevenness of the entire casting band 72 of 0.5% or less.

It is preferable to adjust the tension generated in the casting band 72 when the rotary rollers 73 and 74 are driven to be 1.5 × 10 ⁴ kg / m. Further, the relative speed difference between the casting band 72 and the rotary rollers 73 and 74 is adjusted to be 0.01 m / min or less. The speed fluctuation of the casting band 72 is preferably 0.5% or less, and the meandering in the width direction that occurs when the casting band 72 rotates once is preferably 1.5 mm or less. In order to control this meandering, it is more preferable to provide a detector (not shown) for detecting both ends of the casting band 72 and perform feedback control based on the measured value. Furthermore, it is preferable to adjust so that the vertical position fluctuation accompanying the rotation of the rotary roller 73 on the surface of the casting band 72 immediately below the casting die 71 is 200 μm or less.

It is also possible to use the rotating rollers 73 and 74 directly as a support. In this case, it is preferable to rotate with high accuracy so that the rotation unevenness is 0.2% or less. In this case, it is preferable that the average roughness of the surfaces of the rotary rollers 73 and 74 is 0.01 μm or less. Therefore, chrome plating is performed to provide sufficient hardness and durability. Further, it is necessary to minimize the surface defects of the support (the casting band 72 and the rotating rollers 73 and 74). Specifically, there are no pinholes of 30 μm or more, pinholes of 10 μm or more and less than 30 μm are 1 / m ² or less, and pinholes of less than 10 μm are preferably ² / m ² or less.

  A casting film 80 is formed by co-casting a dope (air surface dope, intermediate layer dope, support surface dope) from the casting die 71 on the casting band 72 while forming a casting bead. In addition, it is preferable that the temperature of each dope at this time is -10 degreeC-57 degreeC. In order to stabilize the formation of the casting bead, the decompression chamber 81 is preferably attached to the rear surface of the casting bead and adjusted to a desired pressure. The back surface of the bead is preferably decompressed in the range of −10 Pa to −2000 Pa rather than the pressure with the front surface. Furthermore, in order to keep the temperature of the decompression chamber 81 at a predetermined temperature, it is preferable to attach a jacket (not shown). The temperature of the decompression chamber 81 is not particularly limited, but is preferably in the range of 10 ° C to 50 ° C. In addition, it is preferable to attach a suction device (not shown) to the edge portion of the casting die 71 in order to obtain the desired shape of the casting bead. The edge suction air volume is preferably in the range of 1 L / min to 100 L / min.

  The casting die 71, the casting band 72, and the like are accommodated in a casting chamber 82. A temperature control facility 77 is attached to the casting chamber 82 so that the inside of the casting chamber 82 is maintained at a constant temperature. The temperature of the casting chamber 82 is preferably −10 ° C. to 57 ° C. In the casting chamber 82, a drying casing 84 and a hot air circulation device 85 constituting a drying facility 83 are provided. The drying casing 84 is disposed above the casting band 72 so as to surround the casting film 80. The hot air circulation device 85 circulates hot air in the drying casing 84 to volatilize the solvent in the casting film 80 and dry the casting film 80. The casting film 80 moves along with the traveling of the casting band 72 and is dried by passing through the drying casing 84 so as to have a self-supporting property, and can be peeled off. As will be described in detail later, the present invention is devised in the drying equipment 83 to foam the solvent in the casting film 80, the remaining peeling when the casting film 80 is peeled off, and the subsequent tenter process. This prevents problems such as biting and tearing when gripped.

  After the casting film 80 has a self-supporting property, it is peeled off from the casting band 72 as a wet film 87 while being supported by a peeling roller 86. Thereafter, the transfer section 90 provided with a large number of rollers is conveyed and then fed into the tenter 100. In the transfer part 90, the drying of the wet film 87 is advanced by sending the drying air of desired temperature from the air blower 91. FIG. At this time, the temperature of the drying air is preferably 20 ° C to 250 ° C. In the crossover section 90, it is also possible to give the wet film 87 a draw by making the rotation speed of the downstream roller faster than the rotation speed of the upstream roller.

[Tenter process]
The wet film 87 sent to the tenter 100 is dried while being transported with its both edges held by clips. Moreover, it is preferable to divide the inside of the tenter 100 into different temperature zones to adjust the drying conditions. Further, the wet film 87 may be stretched in the width direction in the tenter 100. In this case, it is preferable that at least one direction of the wet film 87 in the casting direction and the width direction is stretched by 0.5% to 300% by the crossing portion 90 and / or the tenter 100.

  In the polymer film of the present invention, it is preferable that the axial shift between the slow axis of an arbitrary region of the film and the slow axis of all the regions adjacent to the arbitrary region is less than 2.0 degrees. In addition, it is more preferable that the axial deviation is less than 1.0 degree. Moreover, it is a polymer film manufactured by the solution casting method, and it is preferable to relax in the width direction of the film after stretching in the width direction of the film when performing the solution casting method.

  The stretching and the relaxation are performed by gripping the film with gripping means. When the both ends of the film are gripped, the width of the film is L1 (mm), and the film is stretched to the maximum in the width direction. When the film width is L2 (mm) and the film width is L3 (mm) when the film is relaxed and the gripping means releases the film, 1 <(L2-L3) / L1 × 100 <15 Preferably there is. During the stretching relaxation, the film drying temperature is preferably maintained at substantially the same temperature in the range of 50 ° C. or higher and 180 ° C. or lower.

  The polymer film is preferably an optical film. The polymer film is preferably a cellulose ester film. The cellulose ester film is preferably a cellulose acylate film, more preferably a cellulose acetate film, and most preferably a cellulose triacetate film. Moreover, what uses the said cellulose-ester film for various optical functional films is also contained in this invention. For example, a photographic material base film, a polarizing plate protective film, an optical compensation film base film, and the like. Furthermore, the present invention includes a liquid crystal display device configured using the optical functional film.

  The wet film 87 dried to a predetermined residual solvent amount by the tenter 100 is sent out as a film 101. Both edges of the film 101 are cut at both ends by the ear clip device 102. The cut film is sent to the crusher 103 by a cutter blower (not shown). The edge of the film is crushed by the crusher 103 into chips. It is advantageous in terms of cost to reuse this chip for dope preparation. In addition, although the process of cut | disconnecting the both edges of this film can also be abbreviate | omitted, it is preferable to carry out in either from the said casting process to the process of winding up the said film.

  Next, the film 101 is sent to a drying chamber 105 provided with a large number of rollers 104. Although the temperature in the drying chamber 105 is not specifically limited, It is preferable that it is the range of 50 to 180 degreeC. In the drying chamber 105, the film 101 is conveyed while being wound around the roller 104, and the solvent is volatilized and dried. Further, an adsorption recovery device 106 is attached to the drying chamber 105. The volatile solvent is adsorbed and recovered by the adsorption recovery device 106. The air from which the solvent component has been removed is blown into the drying chamber 105 as dry air. The drying chamber 105 is more preferably divided into a plurality of sections in order to change the drying temperature. In addition, if a preliminary drying chamber (not shown) is provided between the ear opener 102 and the drying chamber 105 and the film 101 is preliminarily dried, a change in the shape of the film due to a sudden rise in the film temperature can be suppressed. preferable.

  The film 101 is conveyed to the cooling chamber 107 and cooled to approximately room temperature. Note that a humidity control chamber (not shown) may be provided between the drying chamber 105 and the cooling chamber 107. Air adjusted to the desired humidity and temperature of the film 101 is blown in the humidity control chamber. Thereby, it is possible to suppress the occurrence of curling of the film 101 and the occurrence of winding failure during winding.

  A forced charge removal device (charge removal bar) 108 is provided so that the charged voltage during the conveyance of the film 101 falls within a predetermined range (for example, −3 kV to +3 kV). In the figure, an example provided on the downstream side of the cooling chamber 107 is illustrated, but the position is not limited thereto. Further, it is preferable that a knurling roller 109 is provided to give knurling to both edges of the film 101 by embossing. In addition, it is preferable that the unevenness | corrugation of the knurled location is 1 micrometer-200 micrometers.

[Winding process]
Finally, the film 101 is taken up by the take-up roller 111 in the take-up chamber 110. At this time, it is preferable to wind the sheet while applying a desired tension with the press roller 112. More preferably, the tension is gradually changed from the start to the end of winding. The film 101 to be wound is preferably at least 100 m in the longitudinal direction (casting direction). Further, the width direction is preferably 600 mm or more, and more preferably 1400 mm or more and 1800 mm or less. However, it is also effective when it is larger than 1800 mm. The thickness of the film can also be applied when manufacturing a thin film having a thickness of 15 μm to 100 μm.

  In the solution casting method of the present invention, when casting dopes, two or more kinds of dopes are simultaneously laminated or sequentially laminated. Furthermore, you may combine both casting. When performing simultaneous lamination and co-casting, a casting die 71 to which a feed block 70 is attached may be used as shown in FIG. 2, or a multi-manifold casting die may be used. It is preferable that the thickness of the layer on the air surface side and / or the thickness of the layer on the support side is 0.5% to 30% in the total film thickness of the film composed of multiple layers by co-casting. Furthermore, when performing simultaneous lamination co-casting, it is preferable to enclose the high-viscosity dope with the low-viscosity dope when casting the dope from the die slit to the support. Moreover, when performing simultaneous lamination co-casting, it is preferable that the dope inside is encapsulated with a dope having a higher alcohol composition ratio than the dope when the dope is cast from the die slit to the support.

  As shown in FIG. 2, the desired characteristics of the film 101 can be easily obtained by co-casting three kinds of dopes. That is, when winding the film 101 as a roll, it is necessary to prevent adhesion between the film surfaces. Therefore, it is preferable to add a matting agent in the dope, but the matting agent usually causes deterioration of optical properties (for example, deterioration of transparency). Therefore, as in this embodiment, the matting agent is contained in the dope for the support surface and the dope for the air surface, which are the front and back surfaces of the film, and is not included in the dope for the intermediate layer. It is possible to obtain the optical characteristics.

  From casting die, decompression chamber, support structure, co-casting, peeling method, stretching, drying conditions of each process, handling method, curl, winding method after flatness correction, solvent recovery method, film recovery method The details are described in paragraphs [0617] to [0889] of JP-A-2005-104148. These descriptions are also applicable to the present invention.

[Performance / Measurement method]
(Curl degree / thickness)
The performance of the wound cellulose acylate film and the measuring method thereof are described in paragraphs [1073] to [1087] of JP-A-2005-104148. These are also applicable to the present invention.

[surface treatment]
It is preferable that at least one surface of the cellulose acylate film is surface-treated. The surface treatment is preferably at least one of vacuum glow discharge treatment, atmospheric pressure plasma discharge treatment, ultraviolet irradiation treatment, corona discharge treatment, flame treatment, acid treatment or alkali treatment.

[Functional layer]
(Antistatic, hardened layer, antireflection, easy adhesion, antiglare)
At least one surface of the cellulose acylate film may be undercoated.

  Further, it is preferable to use the cellulose acylate film as a base film as a functional material provided with another functional layer. The functional layer is preferably provided with at least one layer selected from an antistatic layer, a cured resin layer, an antireflection layer, an easy adhesion layer, an antiglare layer and an optical compensation layer.

The functional layers preferably contain at least one surfactant 0.1mg / m ² ~1000mg / m ² containing. Moreover, it is preferable that the said functional layer contains 0.1 mg / m2-1000 mg / m < ² > of at least 1 type of slip agent. Further, the functional layers preferably contain at least one sort of matting agents in the 0.1mg / m ² ~1000mg / m ² containing. Further, the functional layers preferably contain at least one sort of antistatic agents 1mg / m ² ~1000mg / m ² containing. In addition to the above, the method for applying a surface-treated functional layer for realizing various functions and properties on cellulose acylate film is described in paragraphs [0890] to [1072] of JP-A-2005-104148. Detailed conditions and methods are also described. These are also applicable to the present invention.

(Use)
The cellulose acylate film is particularly useful as a polarizing plate protective film. For example, there may be mentioned a case where two polarizing plates each having a cellulose acylate film bonded together are prepared and these are bonded to a liquid crystal layer to form a liquid crystal display device. However, this arrangement may be any position. Japanese Patent Application Laid-Open No. 2005-104148 (for example, paragraphs [1088] to [1265]) describes in detail TN type, STN type, VA type, OCB type, reflection type, and other examples of liquid crystal display devices. ing. This method can also be applied to the present invention. The application also describes a cellulose acylate film provided with an optically anisotropic layer and a cellulose acylate film provided with antireflection and antiglare functions. Furthermore, the use as an optical compensation film is also described as a biaxial cellulose acylate film imparting appropriate optical performance. This can also be used as a polarizing plate protective film. These descriptions are also applicable to the present invention.

  Hereinafter, the drying equipment 83 according to the present invention will be described in detail. As shown in FIG. 3, the drying facility 83 is provided with an air outlet 120 and an air inlet 122 on the upstream side and the downstream side in the casting direction of the casting film 80 with the drying casing 84 interposed therebetween. The air blowing port 120 is formed long in the width direction of the casting film 80 and is disposed in the vicinity of the casting die 71. Then, hot air for drying the casting film 80 is blown from the blowing port 120 toward the downstream side in the casting direction. An intake port 122 is provided on the downstream side of the air blowing port 120 in the casting direction. The air inlet 122 sucks in ambient air including a solvent that has volatilized by the hot air from the air outlet 120.

  The air sucked from the intake port 122 is sent to the hot air circulation device 85. The hot air circulation device 85 includes a condenser (condenser) 124 that condenses the organic solvent that has volatilized in the air, a recovery device 126 that recovers the condensed organic solvent, and a heater 128. The hot air circulation device 85 coagulates and removes the solvent contained in the air from the air inlet 122 by the condenser 124 and the recovery device 126, then heats the air from which the solvent has been removed by the heater 128 and blows the air again. Air is blown from the opening 120 to the casting film 80. The recovered solvent is reused as a dope preparation solvent.

  The drying casing 84 includes a pair of wind shielding plates 130 and 132 facing each other in the width direction of the casting film 80, and a top plate 134 disposed above the wind shielding plates 130 and 132. It is provided so as to surround a hot air path connecting the intake port 122. The wind shielding plates 130 and 132 are formed long in the casting direction so that one side portion 130a and 132a (see FIG. 4) of each of the wind shielding plates 130 and 132 is located in the vicinity of both sides of the casting film 80. Be placed. The top plate 134 has a rectangular shape and connects the side portions 130b and 132b (see FIG. 4) on the opposite side to the side portions 130a and 132a on the casting film 80 side of the wind shielding plates 130 and 132. It is arranged in parallel with the casting band 72. Then, hot air from the air outlet 120 is blown into an area surrounded by the wind shielding plates 130 and 132, the top plate 134, and the casting band 72. By carrying out like this, the hot air from the ventilation port 120 can be utilized efficiently, and the time required for drying the casting film 80 can be shortened. The wind shielding plates 130 and 132 and the top plate 134 can be formed using an arbitrary material, but it is preferable to use SUS in consideration of the influence of rust or the like, and in particular, SUS316 or SUS316L is used. It is preferable.

  As shown in FIG. 4, the wind shielding plates 130 and 132 are respectively attached to the top plate 134 by shafts 136 on the side portions 130 b and 132 b opposite to the side portions 130 a and 132 a on the casting film 80 side. The casting film 80 is rotatably held in a plane parallel to the width direction. The wind shielding plates 130 and 132 are driven by a moving mechanism 138. The moving mechanism 138 includes a cam, a gear, and a motor, and rotates and moves the wind shielding plates 130 and 132 based on an operation signal input from the operation unit 140. By this rotation, the width W1 between the side portions 130a and 132a of the wind shielding plates 130 and 132 on the casting film 80 side changes, and the hot air blowing range changes.

  The operator of the casting process operates the operation unit 140 to adjust the position of the wind shielding plates 130 and 132 so that hot air is blown to an appropriate range according to the width of the casting film 80. Thus, since the wind shields 130 and 132 are movable, even if the width of the casting film 80 changes, the hot air blowing range can be changed accordingly. As a result, the hot air blowing range is too wide, the hot air hits the casting band 72, heats it, the temperature of both sides in the width direction of the casting film 80 rises and foams, and hot air blowing. When the range is too narrow, hot air is not blown to both sides of the casting film 80 in the width direction, and the drying of this part becomes insufficient. It is possible to prevent biting and tearing.

  The windshields 130 and 132 have a width W1 between the side portions 130a and 132a that is greater than 0.8 times and less than 1.2 times the width W2 of the casting film 80, and in particular, the width W1 is 0 of the width W2. It is preferable to move to a position that is 9 to 1.1 times. If the width W1 is wider than this, hot air may hit the casting band 72, and problems such as foaming may occur at both sides in the width direction of the casting film 80. On the other hand, if the width W1 is narrower than this, drying of both sides in the width direction of the casting film 80 becomes insufficient, and there is a possibility that problems such as unpeeling and biting off may occur.

  The movable range of the wind shielding plates 130 and 132 is not particularly limited, but from the viewpoint of efficiently blowing hot air to the casting film 80, the width W1 is the width between the opposite side portions 130b and 132b. It is preferable to make it wider than W3 (see FIG. 4). In particular, it is preferable to rotate the wind shield plates 130 and 132 within an angle θ (see FIG. 4) formed by the casting film 80 and the wind shield plates 130 and 132 in a range of 45 ° to 90 °.

  Further, when the cast film 80 is peeled off, the weight of the solvent remaining in the cast film 80 (residual solvent amount) is in the range of 100% to 400% of the weight of the film, particularly 200% to 350. % Is preferable. Normally, the volatile content in the dope to be cast is around 350%. However, the higher the ratio of the volatile content, the easier the foaming occurs on both sides of the cast film 80. It can be seen. The weight when the casting film 80 at the time of peeling was dried at 115 ° for 1 hour is the weight of the film, and the weight of the casting film 80 at the time of peeling is subtracted from the weight of the film. The weight of the solvent remaining in the casting film 80 at the time of stripping is used.

  Further, when the casting film 80 is peeled off, the residual solvent amount on both sides in the width direction of the casting film 80 is 0.9 to 1.1 times the residual solvent amount in the center part in the width direction of the casting film 80. It is preferable to adjust the air blowing range by moving the wind shielding plates 130 and 132 so that In this way, good peeling can be performed by suppressing drying unevenness in the width direction of the casting film 80. In addition, the width direction both sides of the casting film 80 refer to a range of 1% to 15% of the width W2 of the casting film 80 from both sides of the casting film 80 in the width direction. The term “range” refers to a range of 40% to 60% of the width W2 of the casting film 80 from the width direction 1 side of the casting film 80.

  In the film, the plasticizer is 3% to 20% by weight, the ultraviolet absorber is 0.001% to 5% by weight, and the fine particle powder (matting agent) is 0.001% by weight to the TAC. 5% by weight is preferably contained.

  Further, in the wind shielding plates 130 and 132, the gap G (see FIG. 4) between the side portions 130a and 132a on the casting film 80 side and the casting film 80 is in the range of 5 mm to 30 mm, particularly 18 mm to 20 mm. It is preferable to move within the range. If the gap G is too narrow, the wind shields 130 and 132 may come into contact with the casting band 72 and cause damage to it when trouble occurs. On the other hand, if the gap G is too wide, the hot air leaks from here to heat the casting band 72, and foaming may occur on both sides in the width direction of the casting film 80.

  By the way, when the wind shielding plates 130 and 132 are pivotal as in the present embodiment, when the wind shielding plates 130 and 132 are rotated, the gap G changes accordingly. It is conceivable that when the wind shields 130 and 132 are moved so that hot air can be blown, the gap G will not be within the above range. In such a case, as shown in FIG. 5, telescopic wind shields 150 and 152 may be used. The wind shielding plates 150 and 152 are each composed of two members: a first member 153 and 155 disposed on the casting film 80 side, and a second member 154 and 156 disposed on the top plate 134 side. ing. The first members 153 and 155 and the second members 154 and 156 are connected by a known slide mechanism. By so doing, the gap G can be adjusted by expanding and contracting the wind shielding plates 150 and 152, so that the gap G can be kept within the above range even if the wind shielding plates 150 and 152 are moved.

  In addition, it is not limited to this as an example which moves a windshield plate, keeping the clearance gap G in the said range, For example, when the windshield plate was moved up and down with the rotation of the windshield plate Is also possible. Moreover, you may use the wind shield plate freely slidable in the width direction of a casting film, without using a rotational wind shield plate like the said embodiment.

  Moreover, although the said embodiment demonstrated the example in which an operator moves a windshield plate manually in a casting process, you may make it move a windshield plate automatically. In this case, a sensor that measures the width of the cast film and a control mechanism that drives the moving mechanism to move the wind shield based on the width information of the cast film input from the sensor may be provided. . Furthermore, in the said embodiment, although demonstrated by the example using two windshields, this invention is not limited to this. For example, a plurality of a pair of wind shielding plates facing each other in the width direction of the casting film may be arranged side by side along the casting direction. In this way, the hot air blowing range can be controlled more finely.

  In the above embodiment, the drying facility having the wind shielding plate has been described as an example arranged immediately after the casting die. However, the drying facility has a casting film after the dope is cast on the casting band. You may arrange | position in any position until it is stripped off. For example, a drying facility may be provided immediately before the casting film is peeled off. Furthermore, it is possible to provide drying facilities at two locations, immediately after the casting die and immediately before the stripping position.

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

The used mass part is shown below.
[composition]
Cellulose triacetate (acyl group substitution degree 2.84, viscosity average degree of polymerization 306, water content 0.2 mass%, viscosity 315 mPa · s in 6 mass% dichloromethane solution, average particle diameter 1.5 mm, standard deviation 0 Powder of 0.5 mm) 100 parts by mass dichloromethane (first solvent) 320 parts by mass methanol (second solvent) 83 parts by mass 1-butanol (third solvent) 3 parts by mass triphenyl phosphate (plasticizer A) 6 parts by weight diphenyl phosphate (plasticizer B) 3.8 parts by weight

[Cotton compound]
The cellulose triacetate used here has a residual acetic acid content of 0.1% by mass or less, a Ca content of 58 ppm, a Mg content of 42 ppm, a Fe content of 0.5 ppm, a free acetic acid of 40 ppm, It contained 15 ppm of sulfate ions. The degree of substitution of the 6-position acetyl group was 0.91, 32.5% of the total acetyl. The acetone extract was 8% by mass, and the weight average molecular weight / number average molecular weight ratio was 2.5. The yellow index is 1.7, the haze is 0.08, the transparency is 93.5%, the Tg (glass transition temperature; measured by DSC) is 160 ° C., and the crystallization heat generation is 6.4 J / g. Met. This cellulose triacetate was synthesized from cellulose collected from cotton as a raw material.

(1) Raw material dope preparation The raw material dope production line 10 shown in FIG. 1 was used. The cellulose triacetate powder (flakes) is gradually added from the hopper 14 to the 4000 L stainless steel dissolution tank 13 having the stirring blades 19 and 21 while mixing and dispersing the plurality of solvents as a mixed solvent. Was adjusted to 2000 kg. In addition, all the solvents used that the water content is 0.5 mass% or less. A dissolver-type eccentric stirring shaft 21 that stirs in the dissolution tank 13 at a peripheral speed of 5 m / sec (shear stress 5 × 10 ⁴ kgf / m / sec ² ) at first, and an anchor blade 19 on the central shaft. And dispersed for 30 minutes under the condition of stirring at a peripheral speed of 1 m / sec (shear stress 1 × 10 ⁴ kgf / m / sec ² ). The starting temperature of dispersion was 25 ° C., and the final temperature reached 48 ° C. After completion of the dispersion, the high-speed stirring was stopped, the peripheral speed of the anchor blade 19 was set to 0.5 m / second, and the stirring was further performed for 100 minutes to swell the cellulose triacetate flakes, thereby obtaining a swelling liquid 22. Until the end of swelling, the inside of the tank was pressurized to 0.12 MPa with nitrogen gas. At this time, the oxygen concentration in the tank was less than 2 vol%, and the state of no problem was maintained in terms of explosion protection. The water content in the raw material dope was 0.3% by mass.

(2) Dissolution / filtration The swelling liquid 22 was fed from the dissolution tank 13 to the jacketed pipe 26 by the pump 25. It heated to 50 degreeC with the piping 26 with a jacket, and also heated to 90 degreeC under the pressurization of 2 MPa, and was dissolved completely. The heating time was 15 minutes. The temperature was lowered to 36 ° C. with a temperature controller 27 and passed through a filtration device 28 having a filter medium having a nominal pore diameter of 8 μm to obtain a raw material dope having a solid content concentration of 19% by mass (hereinafter referred to as a raw material dope before concentration). At this time, the primary pressure of filtration was 1.5 MPa, and the secondary pressure was 1.2 MPa. In addition, the filter, housing, and piping exposed to high temperature used the thing which has a jacket which distribute | circulates the heat medium for heat insulation heating using the thing made from Hastelloy alloy and excellent in corrosion resistance.

(3) Concentration, filtration, and defoaming The raw material dope before concentration is flushed in a flash device 31 adjusted to 80 ° C. and normal pressure, and the evaporated solvent is liquefied by a condenser and recovered and separated by a recovery device 32. . The solid content concentration of the raw material dope after the flash was 21.8% by mass. The recovered solvent was adjusted for reuse by the regenerator 33. The flash tank of the flash unit 31 had an anchor blade on the central axis, and deaerated by stirring at a peripheral speed of 0.5 m / sec. The temperature of the raw material dope in the flash tank was 25 ° C., and the average residence time in the tank was 50 minutes. The shear viscosity of this raw material dope collected and measured at 25 ° C. was 450 Pa · s at a shear rate of 10 (1 / second).

  Next, bubbles were removed by irradiating the raw material dope with weak ultrasonic waves. Thereafter, the liquid was fed to the filtration device 35 while being pressurized to 1.5 MPa using the pump 34. In the filter device 35, first, the sintered fiber metal filter having a nominal pore diameter of 10 μm was passed, and then, the sintered fiber filter having the same pore diameter of 10 μm was passed. Respective primary pressures were 1.5 MPa and 1.2 MPa, and secondary pressures were 1.0 MPa and 0.8 MPa. The temperature of the raw material dope after filtration was adjusted to 36 ° C. and stored in a 2000 L stainless steel stock tank 30. The stock tank 30 had an anchor blade 42 on the center axis and was constantly stirred at a peripheral speed of 0.3 m / sec. When preparing the raw material dope from the pre-concentration dope, no problems such as corrosion occurred at all in the wetted parts of the dope of each apparatus.

(4) Discharge Film deposition was performed using the film deposition line 40 shown in FIG. Subsequently, the raw material dope 36 in the stock tank 30 was fed by the feedback control by the inverter motor so that the primary pressure of the high precision gear pump became 0.8 MPa with the primary pressure increasing gear pumps 46, 47, 48. The high-precision gear pumps 46 to 48 had a volume efficiency of 99.2% and a discharge rate variation rate of 0.5% or less. The discharge pressure was 1.5 MPa.

  The casting die 71 is equipped with a feed block 70 having a width of 1.8 m and adjusted for co-casting, and is capable of forming a three-layer film by laminating on both sides in addition to the mainstream. Was used. In the following description, a layer formed from the mainstream is referred to as an intermediate layer, a support surface side layer is referred to as a support surface, and an opposite surface is referred to as an air surface. In addition, the dope liquid supply flow path used three flow paths: an intermediate layer dope flow path 43, a support surface dope flow path 44, and an air surface dope flow path 45.

(5) Production of dope UV agent a (2 (2'-hydroxy-3 ', 5'-di-tert-butylphenyl) benzotriazole), UV agent b (2 (2'-hydroxy-3', 5 ' -Di-tert-amylphenyl) 5-chlorobenzotriazole) and a retardation control agent (N, N'-di-m-tolyl-N "-p-methoxyphenyl-1,3,5-triazine-2, 4,6-triamine), 86.5 parts by mass of dichloromethane, 13 parts by mass of acetone, 0.5 parts by mass of n-butanol, and the raw material dope 36 are mixed with stock solution 51 for intermediate layer. Placed in tank 50. The intermediate layer additive solution 51 was fed to the raw material dope 36 in the intermediate layer dope channel 43 by the pump 52. And it mixed through the static mixer 53, and the dope for intermediate | middle layers was produced | generated.

  0.05 parts by mass of silicon dioxide (particle size: 15 nm, Mohs hardness: about 7) as matting agent and citric acid ester mixture (citric acid, citric acid monoethyl ester, citric acid diethyl ester, citric acid triethyl ester) as peeling accelerator ) Was dissolved or dispersed in 0.006 parts by mass, the raw material dope 36 and the mixed solvent 37 to obtain a support surface addition liquid 56. The support surface additive liquid 56 was placed in the stock tank 55 and fed to the raw material dope 36 flowing in the support surface dope channel 44 at a desired flow rate using a pump 57. And it was made to mix with the static mixer 58, and the dope for support body surfaces was produced | generated.

  An air surface additive solution 61 was prepared by dispersing in a silicon dioxide mixed solvent 37 and placed in a stock tank 60. The air surface additive solution 61 was fed to the raw material dope 36 in the air surface dope channel 45 by the pump 62. And it was made to mix through the static mixer 63 and the dope for air surfaces was produced | generated.

(6) Casting Each of the dopes (for the intermediate layer) so that the film thickness (air surface, intermediate layer, support surface) of the target TAC film is 4 μm, 73 μm, and 3 μm, respectively, and the product thickness is 80 μm. Casting was carried out by adjusting the flow rate of the dope, the dope for the support surface, and the dope for the air surface. The casting was performed such that the width W2 of the casting film 80 was 1570 mm. In order to adjust the temperature of each dope to 36 ° C, a jacket (not shown) was provided on the casting die 71, and the inlet temperature of the heat transfer medium supplied into the jacket was set to 36 ° C.

  The casting die 71, the feed block 70, and the piping were all kept at 36 ° C. during film formation. The casting die 71 was a coat hanger type, and thickness adjusting bolts (heat bolts) were provided at a pitch of 20 mm, and those equipped with an automatic thickness adjusting mechanism using heat bolts were used. The heat bolt can also set a profile according to the liquid feed amount of the high-precision gear pump by a preset program, and can be set by an adjustment program based on the profile of an infrared thickness meter (not shown) installed in the film deposition line 40 The feedback control also has a possible performance. The thickness difference between two arbitrary points separated by 50 mm in the film excluding the casting edge portion of 20 mm was within 1 μm, and the maximum difference in the width direction thickness was adjusted to be 3 μm / m or less. The average thickness accuracy of each layer was controlled so that both outer layers were controlled to ± 2% or less, the mainstream was controlled to ± 1% or less, and the total thickness was adjusted to ± 1.5% or less.

  A decompression chamber 81 for decompressing was installed on the primary side of the casting die 71. The degree of decompression of the decompression chamber 81 is such that a pressure difference of 1 Pa to 5000 Pa occurs before and after the casting bead and can be adjusted according to the casting speed. Moreover, the temperature of the decompression chamber 81 was equipped with the mechanism which can be set higher than the condensation temperature of the gas around a casting part. Labyrinth packings (not shown) were provided at the front and rear of the bead. Furthermore, the thing which provided the opening part in the both ends and attached the edge suction device (not shown) from there in order to adjust disturbance of the both edges of a casting bead was used.

The material of the casting die 71 is a double-layer stainless steel, and has a thermal expansion coefficient of 2 × 10 ⁻⁵ (° C. ⁻¹ ) or less, and is approximately the same corrosion resistance as that of SUS316 in a forced corrosion test with an aqueous electrolyte solution. The material which has the property was used. Further, a corrosion-resistant material that does not cause pitting (opening) at the gas-liquid interface even when immersed in a mixed solution of dichloromethane, methanol, and water for 3 months was used. The finishing accuracy of the wetted surfaces of the casting die 71 and the feed block 70 was 1 μm or less in terms of surface roughness, the straightness was 1 μm / m or less in any direction, and the slit clearance was adjusted to 1.5 mm. About the corner | angular part of the liquid-contact part of die-tip tip, it processed so that R might be 50 micrometers or less over the slit full width. The shear rate inside the die ranged from 1 (1 / second) to 5000 (1 / second). Note that a WC coating was applied to the lip end of the casting die 71 by a thermal spraying method to provide a cured film.

  Furthermore, in order to prevent the dope flowing out from the slit end of the casting die 71 from locally drying and solidifying, the mixed solvent solubilizing the dope is placed on one side of the casting bead end and the slit gas-liquid interface. At 0.5 ml / min. The pulsation rate of the pump supplying this liquid was 5% or less. Further, the pressure on the back surface of the bead was reduced by 150 Pa by the decompression chamber 81. In order to keep the temperature of the decompression chamber 81 constant, a jacket (not shown) was attached. A heat transfer medium adjusted to 35 ° C. was supplied into the jacket. The edge suction air volume that can be adjusted in the range of 1 L / min to 100 L / min was used, and in this example, it was appropriately adjusted in the range of 30 L / min to 40 L / min.

A stainless steel endless band having a width of 2.1 m and a length of 70 m was used as the casting band 72 as a support. The casting band 72 was 1.5 mm in thickness and polished so that the surface roughness was 0.05 μm or less. The material was made of SUS316 and had sufficient corrosion resistance and strength. The thickness unevenness of the entire casting band 72 was 0.5% or less. The casting band 72 was driven by two rotating rollers 73 and 74. At this time, the tension of the casting band 72 is adjusted to 1.5 × 10 ⁴ kg / m so that the relative speed difference between the casting band 72 and the rotating rollers 73 and 74 is 0.01 m / min or less. did. The speed fluctuation of the casting band 72 was 0.5% or less. Furthermore, the position of both ends of the casting band 72 was detected and controlled so that the meandering in the width direction of one rotation was limited to 1.5 mm or less. The vertical position variation between the die lip tip and the casting band 72 immediately below the casting die 71 was set to 200 μm or less.

As the rotating rollers 73 and 74, those capable of feeding a heat transfer medium therein were used so that the temperature of the casting band 72 could be adjusted. A heat transfer medium (water) at 5 ° C. was passed through the rotary roller 73 on the casting die 71 side, and a heat transfer medium (water) at 40 ° C. was passed through the other rotary roller 74. The surface temperature of the center part of the casting band 72 immediately before casting was 15 ° C., and the temperature difference between both ends was 6 ° C. or less. The casting band 72 preferably has no surface defects, has no pinholes of 30 μm or more, has no pinholes of 10 μm to 30 μm, 1 pin / m ² or less, and has 2 pinholes of less than 10 μm / m2. What was ² or less was used.

(7) Drying / peeling The casting film 80 formed from the dope cast on the casting band 72 was passed through a drying casing 84 and dried by blowing hot air. The top plate 134 has a width of 1470 mm, and wind shielding plates 130 and 132 are rotatably attached to both sides of the top plate 134. The overall heat transfer coefficient from the hot air to the cast film 80 was 24 kcal / m ² · hour · ° C. The saturation temperature of hot air was around -8 ° C. The oxygen concentration in the dry atmosphere on the casting band 72 was kept at 5 vol%. In order to keep the oxygen concentration at 5 vol%, the air was replaced with nitrogen gas. The temperature of the casting chamber 82 was kept at 35 ° C. using the temperature control equipment 77.

  Static pressure fluctuations immediately around the casting die 71 were suppressed to ± 1 Pa or less. Further, the position of the air blowing port 120 was adjusted so that the hot air did not directly hit the dope and the casting film 80 for 5 seconds after casting. When the solvent ratio in the cast film 80 reached 150% by mass on the dry basis, the film was peeled off from the casting band 72 as a film 87 (hereinafter referred to as a wet film) while being supported by a peeling roller. The peeling tension at this time is 10 kgf / m, and the peeling speed (peeling roller draw) is in the range of 100.1% to 110% with respect to the speed of the casting band 72 in order to suppress the peeling failure. Adjusted appropriately. The surface temperature of the wet film 87 was 15 ° C. The drying rate on the casting band 72 was an average of 60% by mass dry weight reference solvent / min.

  The air containing the solvent sent from the intake port 122 to the hot air circulation device 85 condenses and liquefies the solvent with the condenser 124 having an outlet temperature of −10 ° C., and the liquefied solvent is recovered with the recovery device 126. The recovered solvent was adjusted and then reused as a dope preparation solvent. At that time, the amount of water contained in the solvent was adjusted to 0.5% or less. After removing the solvent from the air from the air inlet 122, it was heated again by the heater 128 and reused as hot air.

(8) Tenter Process The wet film 87 was conveyed through the roller of the crossing section 90 and sent to the tenter 100. At this time, 40 ° C. dry air was blown from the blower 91 to the wet film 87. In addition, a tension of about 20 N was applied to the wet film 87 during the conveyance with the roller of the crossing section 90. The wet film 87 sent to the tenter 100 was conveyed while gripping both ends with clips. The clip was cooled by supplying a heat transfer medium at 20 ° C. The tenter was driven by a chain, and the speed fluctuation of the sprocket was 0.5% or less.

  Further, the tenter 100 was divided into three zones, and the wet film 87 was dried by blowing dry air in each zone. The drying air temperature in each zone was 90 ° C, 100 ° C, and 110 ° C from the upstream side. The gas composition of the drying air was set to a saturated gas concentration of −10 ° C. The average drying rate in the tenter 100 was 120% by mass (dry weight reference solvent) / min. The conditions of each zone were adjusted so that the amount of residual solvent in the film was 7% by mass at the exit of the tenter 100.

  In the tenter 100, stretching in the width direction was also performed while transporting. When the width of the wet film 87 when transported to the tenter 100 is 100%, the widening amount is 103%. The stretching ratio (tenter driven draw) from the peeling roller 86 to the tenter 100 inlet was 102%. As for the stretching ratio in the tenter 100, the difference in the actual stretching ratio in the portion separated by 10 mm or more from the tenter biting portion was 10% or less, and the difference in the stretching ratio at any two points 20 mm apart was 5% or less. . The ratio of the length of the base end fixed with a tenter was 90%. The solvent evaporated in the tenter 100 was condensed and liquefied at a temperature of −10 ° C. and recovered. A condenser (not shown) was provided for condensation recovery, and the outlet temperature was set to -8 ° C. The water content contained in the solvent was adjusted to 0.5% by mass or less and reused. Then, the film was sent out from the tenter 100 as a film 101.

  The ear-cleaving device 102 cuts the ears at both ends within 30 seconds from the exit of the tenter 100. Ears 50 mm on both sides were cut with an NT-type cutter, and the cut ears were blown to a crusher 103 with a cutter blower (not shown) and crushed into chips of about 80 mm 2 on average. This chip was used again as a raw material for dope preparation together with TAC flakes as a dope preparation raw material. The oxygen concentration in the dry atmosphere of the tenter 100 was kept at 5 vol%. Note that the air was replaced with nitrogen gas in order to maintain the oxygen concentration at 5 vol%. Before drying at a high temperature in a drying chamber 105 described later, the film 101 was preheated in a predrying chamber (not shown) to which 100 ° C. drying air was supplied.

  The film 101 was dried at a high temperature in a drying chamber 105. The drying chamber 105 was divided into four sections, and drying air at 120 ° C., 130 ° C., 130 ° C., and 130 ° C. was supplied from the blower (not shown) from the upstream side. The conveying tension of the film 101 by the roller 104 was 100 N / width, and the film was dried for about 10 minutes until the residual solvent amount finally reached 0.3% by mass. The wrap angle of the roller 104 was 90 degrees and 180 degrees (exaggerated in FIG. 2). The roller 104 was made of aluminum or carbon steel, and a hard chrome plating was applied to the surface. The roller 104 has a flat surface shape and a matt-processed surface by blasting. All the vibrations due to the rotation of the roller 104 were 50 μm or less. The roller deflection at a tension of 100 N / width was selected to be 0.5 mm or less.

  The solvent gas contained in the drying air was adsorbed and recovered using the adsorption recovery device 106. The adsorbent was activated carbon, and desorption was performed using dry nitrogen. The recovered solvent was reused as a dope preparation solvent after adjusting the water content to 0.3% by mass or less. In addition to solvent gas, the drying air contains plasticizers, UV absorbers, and other high-boiling substances, so these were removed by a cooler and a pre-adsorber that were cooled and removed, and were recycled and used. And adsorption / desorption conditions were set so that VOC (volatile organic compound) in the outdoor exhaust gas was finally 10 ppm or less. Moreover, the solvent amount collect | recovered by the condensation method among all the evaporation solvents was 90 mass%, and most of the remainder was collect | recovered by adsorption collection.

  The dried film 101 was conveyed to a first humidity control chamber (not shown). A drying air of 110 ° C. was supplied to the transition portion between the drying chamber 105 and the first humidity control chamber. Air having a temperature of 50 ° C. and a dew point of 20 ° C. was supplied to the first humidity control chamber. Further, the film 101 was conveyed to a second humidity control chamber (not shown) that suppresses the curling of the film 101. In the second humidity control chamber, air of 90 ° C. and humidity 70% was directly applied to the film 101.

  The film 101 after humidity control was cooled to 30 ° C. or lower in the cooling chamber 107 and both ends were cut off. The forced charge removal device (charge removal bar) 108 was installed so that the film voltage during conveyance was always in the range of -3 kV to +3 kV. Further, knurling was performed on both ends of the film 101 by a knurling roller 109. The knurling was applied by embossing from one side, the knurling width was 10 mm, and the pressing pressure was set so that the maximum height was 12 μm higher than the average thickness on average.

(9) Winding Then, the film 101 was conveyed to the winding chamber 110. The winding chamber 110 was kept at a room temperature of 28 ° C. and a humidity of 70%. Furthermore, an ion wind static elimination device (not shown) was also installed so that the film voltage would be -1.5 kV to +1.5 kV. The product width of the film (thickness 80 μm) 101 thus obtained was 1475 mm. The diameter of the winding roller 111 was 169 mm. The tension pattern was such that the winding start tension was 360 N / width and the winding end was 250 N / width. The total winding length was 3940 m. The period during winding was 400 m, and the oscillating width was ± 5 mm. Further, the pressing roller 112 was pressed against the winding roller 111 and the pressure was set to 50 N / width. The temperature of the film at the time of winding was 25 ° C., the water content was 1.4% by mass, and the residual solvent amount was 0.3% by mass.

(10) Comparative evaluation In the process of manufacturing the film 101 as described above, in the drying / peeling process shown in (7), the windshields 130 and 132 are moved to change the width W1. Example 1-1 to Example 1-6 were evaluated by examining the occurrence of foaming and biting. The result is shown in FIG. In addition, about foaming, the cast film was observed visually and the presence and extent of foaming were investigated and evaluated. In addition, the bite torn was evaluated by observing visually the clips that grip both sides of the film in the tenter process, and examining the presence and extent of the bite torn.

  In Example 1-1, the width W1 of the wind shielding plates 130 and 132 was set to 0.8 times the width W2 of the cast film. At this time, the residual solvent amount R1 on both sides of the casting film at the time of peeling was 1.5 times the residual solvent amount R2 in the central part of the casting film. In Example 1-1, since foaming did not occur, evaluation of foaming was evaluated as ◎. However, the bite-off was generated, and if it occurred more than this, the quality of the product might be affected.

  In Example 1-2, the width W1 was set to 0.9 times the width W2. At this time, the residual solvent amount R1 was 1.2 times the residual solvent amount R2. In Example 1-2, since foaming did not occur, evaluation of foaming was evaluated as ◎. In addition, since no biting was generated, the biting was evaluated as ◎.

  In Example 1-3, the width W1 is equal to the width W2. At this time, the residual solvent amount R1 and the residual solvent amount R2 were also equal. In Example 1-3, since foaming did not occur, the foaming evaluation was evaluated as “◎”. In addition, since no biting was generated, the biting was evaluated as ◎.

  In Example 1-4, the width W1 was 1.1 times the width W2. At this time, the residual solvent amount R1 was 0.9 times the residual solvent amount R2. In Example 1-4, since foaming did not occur, evaluation of foaming was evaluated as ◎. In addition, since no biting was generated, the biting was evaluated as ◎.

  In Example 1-5, the width W1 was set to 1.2 times the width W2. At this time, the residual solvent amount R1 was 0.8 times the residual solvent amount R2. In Example 1-5, although foaming occurred, the quality of the product was not problematic, so the evaluation of foaming was evaluated as “good”. On the other hand, since no biting occurred, the biting was evaluated as ◎.

  In Example 1-6, the width W1 was set to 1.5 times the width W2. At this time, the residual solvent amount R1 was 0.7 times the residual solvent amount R2. In Example 1-6, foaming occurred, and if it occurred more than this, there was a possibility of causing a problem in product quality. On the other hand, since no biting occurred, the biting was evaluated as ◎.

(11) General comments As described above, it was confirmed that foaming and biting were prevented by moving the wind shield plate and adjusting the hot air blowing range. Moreover, it was confirmed that the position where the width of the windshield plate is larger than 0.8 times and less than 1.2 times the width of the casting film is appropriate as the destination of the windshield plate. Further, when the amount of residual solvent on both sides in the width direction of the cast film at the time of peeling is greater than 0.9 times and less than 1.1 times the amount of residual solvent in the center in the width direction, foaming or biting It was confirmed that it can be prevented.

It is explanatory drawing showing the production line of dope. It is explanatory drawing showing a film forming line. It is a perspective view of a dry casing. It is sectional drawing of a dry casing. It is sectional drawing of the dry casing provided with the elastic windshield. It is a chart showing the relationship between the width | variety of a windshield board, and the generation | occurrence | production state of foaming and a biting tear.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Dope production line 36 Raw material dope 40 Film film forming line 71 Casting die 72 Casting band 80 Casting film 83 Drying equipment 84 Drying casing 85 Hot-air circulation apparatus 130, 132, 150, 152 Windshield 130a, 130b, 132a, 132b Side part 134 Top plate 136 Axis 138 Moving mechanism 140 Operation part

Claims (9)

A polymer is dissolved in a solvent to form a dope, and the dope is cast on a moving support to form a cast film, and then dried by sending dry air to the cast film. In a solution casting apparatus that peels off a casting film to produce a film,
A pair of wind shielding members facing each other in the width direction of the casting film are provided, and by sending the drying air between these wind shielding members, the air blowing range of the drying wind in the width direction of the casting film is regulated, and
A wind-shielding member moving mechanism for moving the wind-shielding member to change the width of the wind-shielding member is provided, the wind-shielding member is moved according to the width of the casting film, and the blowing air blowing range A solution casting apparatus characterized by adjusting the temperature.   2. The solution casting apparatus according to claim 1, wherein the wind-shielding member is formed long in the casting direction of the casting film.   2. The solution casting apparatus according to claim 1, wherein a plurality of the wind shielding members are arranged side by side along the casting direction of the casting film.   The solution according to any one of claims 1 to 3, wherein the wind-shielding member is moved so that the width is greater than 0.8 times and less than 1.2 times the width of the cast film. Membrane device.   The solution casting apparatus according to any one of claims 1 to 4, wherein a gap between the wind-shielding member and the casting film is 5 mm or more and 30 mm or less.   The wind-shielding member is rotatably provided around the rear end side opposite to the casting film-side tip side, and the wind-shielding member is rotated to change the width of the tip side. The solution casting apparatus according to claim 1, wherein the air blowing range of the dry air is adjusted.   The wind-shielding member is rotated so that an angle formed with the casting film is in a range of 45 ° or more and 90 ° or less, and a width on the front end side is wider than a width on the rear end side. The solution casting apparatus according to claim 6.   The windshield member is provided so as to be stretchable in a direction connecting the front end side and the rear end side, and the wind shield member is expanded and contracted together with the rotation so that the length from the front end side to the rear end side is increased. 8. The solution casting apparatus according to claim 6, wherein a gap between the casting film and the wind shielding member is adjusted to change. A polymer is dissolved in a solvent to form a dope, and the dope is cast on a moving support to form a cast film, and then dried by sending dry air to the cast film. In the solution casting method of peeling off the casting film to produce a film,
By sending the drying air between a pair of wind-shielding members facing each other in the width direction of the casting membrane, the air blowing range of the drying air in the width direction of the casting membrane is regulated, and
A solution casting method, wherein the wind-shielding member is moved according to the width of the casting film and the width of the wind-shielding member is changed to adjust the blowing range of the dry air.

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