JP2006297906A - Casting apparatus, solution film forming equipment and solution film forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To manufacture a polymer film excellent in optical characteristics by suppressing the occurrence of unevenness irregularity caused by a drying wind. <P>SOLUTION: A dope containing a solvent and a polymer is casted on a casting band 46 to form a cast film 69 and an air blow duct 70 is provided so that its air blow ports 71a are turned toward the running direction of the casting band 46. The air blow ports 71a are demarcated by a large number of rectifying fins 100 and wind protecting plates 101 are attached to both side members 71b of a duct main body 71. Immediately after the cast film 69 is formed, the drying wind is sent out from the air blow ports 71a so as to become parallel to the casting band 46. The drying wind is sent out from the air blow ports 71a while rectified and, since the accompanied wind produced by the drying wind is suppressed to dry the cast film 69, the occurrence of unevenness irregularity such as oblique irregularity or thickness irregularity in the cast film 69 is suppressed to manufacture the polymer film excellent in flatness. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a casting apparatus, a solution casting apparatus, and a solution casting method.

  Polymer films are widely used for optical applications, and in particular, cellulose acylate films have the advantage that they can be used as protective films for polarizing plates, so that it is possible to provide an inexpensive and thin liquid crystal display device. Widely used as a possible optical film.

  Such a cellulose acylate film is mainly produced by a solution casting method. The solution casting method is a polymer solution containing a polymer such as cellulose acylate and a solvent, that is, a dope is cast on a traveling support to form a cast film, and then a film containing a solvent, In other words, it is a method in which the film is peeled off as a wet film and then dried to form a film.

  In the solution casting method, in order to improve the productivity of the film, a device for increasing the film forming speed is devised. As this device, for example, there is so-called initial drying in which a cast film immediately after being formed on a support is dried by a drying device. When such initial drying is performed, evaporation of the solvent from the cast film can be effectively promoted.

  And when using a ventilation duct as the said drying apparatus, a drying wind is sent out from the ventilation opening so that it may blow in the direction of travel of the said support body parallel to the said support body. However, the air is drawn into the vicinity of the surface of the casting film by the dry air to generate a wind, that is, an accompanying air is generated, and the air current in the vicinity of the casting film is disturbed. Due to the turbulent airflow (winding air), oblique unevenness occurs on the surface of the casting film, or the thickness of the casting film becomes nonuniform (thickness unevenness). Such oblique unevenness and thickness unevenness (hereinafter collectively referred to as uneven unevenness) appear as a decrease in film flatness, and thus the casting film can be dried while suppressing the occurrence of uneven unevenness. The establishment of was desired.

As a method of solving such a problem, an air duct is arranged so that the air blowing port faces obliquely forward in the casting direction, and the direction of the air blowing port is set to 45 degrees to 80 degrees with respect to the support body. While adjusting the wind speed from the air outlet using a method of sending out the dry air and drying the cast film (for example, refer to Patent Document 1), or using an air duct provided with an air outlet and an air outlet at predetermined positions. A method for sending dry air (see, for example, Patent Document 2) has been proposed. Also, a method of drying the air duct provided with a slit-like opening in the uppermost stream of the casting film (see, for example, Patent Document 3) or casting a dope in a casting direction in a casting direction. There has been proposed a method (for example, see Patent Document 4) that installs a windproof plate that extends to suppress the intrusion of wind near the surface of the casting film.
JP-A 64-55214 JP 2001-113545 A JP 2003-103544 A JP 2004-314527 A

  Any of the above methods has a certain effect in suppressing unevenness in unevenness, and a film having a certain degree of flatness can be produced. However, in recent years, with the rapid miniaturization and thinning of electronic and electrical equipment, there is an increasing demand for miniaturization and thinning of optical films. For this reason, the optical film is required to have more excellent flatness, and any of the above-described methods cannot produce a film having sufficient flatness that can meet recent demands.

  Therefore, the present invention provides an apparatus and a method for producing a polymer film that suppresses occurrence of uneven unevenness in a cast film and has excellent flatness.

  The casting apparatus of the present invention includes a casting film forming means for casting a dope from a casting die onto a traveling support to form a casting film, and air is blown to the entire width region of the casting film immediately after the casting film is formed. In the casting apparatus comprising the air blowing means, the air blowing means is provided such that the air blowing port faces in a direction in which the support body travels, and the air to be emitted is substantially parallel to the support body in the air blowing port. A first rectifying member that is divided into a plurality of portions in the width direction of the support is provided so as to blow in the direction of travel of the support. The first rectifying member is preferably provided with a plurality of the air outlets at an installation interval of 30 to 80 mm, and the air blowing means has a substantially box-shaped air blowing portion with the air outlet on one side. It is preferable to provide a windproof member on both side surfaces of the part for suppressing the accompanying wind generated by the blowing.

  The windbreak member is preferably a windbreak plate provided perpendicular to the support and extended toward the support, and a distance C1 between a lower end of the windbreak plate and the casting film. Is preferably 1 to 30 mm. The distance C2 between the lower surface of the air blowing part and the casting film is 1 to 300 mm, and is preferably larger than the distance C1 between the windproof member and the casting film. A rectifying plate as a second rectifying member is provided along the traveling direction of the support body so that the wind emitted from the air blowing port blows substantially parallel to the support body and in the traveling direction of the support body. Is preferred. It is preferable that a plurality of the current plates are provided at an installation interval of 50 to 400 mm in the width direction of the support. The solution casting apparatus of the present invention comprises any one of the above casting apparatuses and a drying means for drying the casting film peeled off as a film from the support.

  The solution casting method of the present invention includes a casting process in which a dope is cast on a traveling support to form a casting film, and the casting film immediately after formation is blown by a blowing means; And a drying step of drying the cast film peeled off as a film, wherein the blower port of the blower means has a blower port over the entire width of the cast film. In addition to turning in the direction and dividing in advance in the width direction of the casting film, the air coming out of the air blowing port is blown in the direction of travel of the support substantially parallel to the support. Features.

  In addition, a plurality of first rectifying members for partitioning the air blowing port into a plurality of width directions are provided in the air blowing port, and an installation interval of the first rectifying members is set according to disturbance in the direction of air blowing from the air blowing port. It is preferable. The blower means has a blower portion with the blower opening on one surface facing the running direction of the support, and the accompanying air generated along with the blown air is suppressed on both side surfaces of the blower portion. Preferably, a windbreak member is provided, and a distance C1 between the windbreak member and the casting film is set according to the wind force of the accompanying wind.

  In the present invention, when forming a cast film by casting a dope from a casting die on a traveling support, the blower is provided with a blowing means so that the blowing port faces in the traveling direction of the support. In addition, since the first rectifying member that is divided into a plurality of parts in the width direction of the support is provided, the air is blown in parallel to the support while controlling the direction of the air to be sent to the casting film Drying can be performed while suppressing unevenness. In addition, since the air blowing means is provided with windproof members in the vicinity of both sides of the air blowing port, it is possible to suppress the accompanying air generated with the air blowing. Further, since the blowing means is sent out to the entire width region of the casting film immediately after being formed by the blowing means while the casting film is rectified before the casting film is completely solidified, the casting film is further fed. It is possible to prevent unevenness from occurring on the surface of the substrate. Therefore, when the present invention is used, the drying air can be sent out while rectifying the cast film formed immediately after casting the dope, so that unevenness of the cast film is prevented from occurring. Thus, a film having excellent flatness can be produced. In addition, the said rectification means adjusting the flow of a wind.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the embodiments listed here.

[material]
In the present embodiment, cellulose acylate is used as the polymer, and triacetyl cellulose (TAC) is particularly preferable as the cellulose acylate. Of the cellulose acylates, those in which the ratio of the hydrogen of the hydroxyl group of cellulose to the acyl group, that is, the degree of acyl substitution, satisfies all of the following formulas (I) to (III) are more preferable. In the formulas (I) to (III), A and B both represent the substitution degree of the acyl group for the hydrogen atom in the hydroxyl group of cellulose. The acyl group in A is an acetyl group, and the acyl group in B has 3 to 22 carbon atoms. In addition, it is preferable that 90 mass% or more of TAC is a particle | grain of 0.1-4 mm. However, the polymer used in the present invention is not limited to cellulose acylate, and may be a known polymer that can be formed into a film by solution casting.
(I) 2.5 ≦ A + B ≦ 3.0
(II) 0 ≦ A ≦ 3.0
(III) 0 ≦ B ≦ 2.9

  Glucose units constituting cellulose and having β-1,4 bonds 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 in which the hydroxyl groups at the 2nd, 3rd and 6th positions are esterified. For example, the substitution degree is 1 when the hydroxyl group at the 2-position is esterified 100%. Therefore, when all the hydroxyl groups at the 2, 3, 6 positions are esterified, the degree of substitution is 3.

  Here, in the glucose unit, the ratio in which the hydrogen at the 2-position hydroxyl group is substituted by an acyl group (hereinafter referred to as the 2-position acyl substitution degree) is DS2, and the hydrogen at the 3-position hydroxyl group is substituted by an acyl group. The ratio (hereinafter referred to as the acyl substitution degree at the 3-position) is DS3, and the ratio at which the hydrogen atom of the hydroxyl group at the 6-position is replaced by an acyl group (hereinafter referred to as the acyl substitution degree at the 6-position) is DS6. The total acyl substitution degree, that is, the value of 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, the value of DS6 / (DS2 + DS3 + DS6) is preferably 0.28 or more, more preferably 0.30 or more, and particularly preferably 0.31 to 0.34.

  The acyl group in cellulose acylate may be one type or two or more types. When there are two or more acyl groups, one of them is preferably an acetyl group. Here, the sum of the degree of substitution of the hydroxyl groups at the 2nd, 3rd and 6th positions by acetyl groups is DSA, and the hydroxyl groups at the 2nd, 3rd and 6th positions are substituted by acyl groups other than the acetyl group. The sum of the degrees is DSB. The value of DSA + DSB is preferably 2.22 to 2.90, particularly 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, further preferably 30% or more, and particularly preferably 33% or more. Further, the DSA + DSB value at the 6-position of the cellulose acylate is 0.75 or more, more preferably 0.80 or more, and particularly preferably 0.85 or more. By using the cellulose acylate as described above, it is possible to produce a solution having superior solubility, that is, a dope. In particular, when a non-chlorine organic solvent is used as the solvent, the cellulose acylate as described above exhibits excellent solubility, and the obtained dope has low viscosity and good filterability.

  Cellulose, which is a raw material for 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 cellulose acylate may be an aliphatic group or an aryl group, and is not particularly limited. For example, cellulose alkylcarbonyl ester, alkenylcarbonyl ester, aromatic carbonyl ester, aromatic alkylcarbonyl ester and the like may be mentioned, and each 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. It is.

  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.). In the present invention, the dope means a polymer solution or dispersion obtained by dissolving or dispersing a polymer in a solvent.

  Among the above halogenated hydrocarbons, those having 1 to 7 carbon atoms are preferable, and dichloromethane is most preferable. From the viewpoint of physical properties such as the solubility of TAC, the peelability of the cast film from the support, the mechanical strength and optical properties of the film, one or several alcohols having 1 to 5 carbon atoms are mixed with dichloromethane. It is preferable. As for the content rate of alcohol, 2-25 mass% is preferable with respect to the whole solvent, More preferably, it is 5-20 mass%. Examples of the alcohol include methanol, ethanol, n-propanol, isopropanol, n-butanol, and the like, and methanol, ethanol, n-butanol, or a mixture thereof is more preferable.

  Recently, a solvent composition that does not use dichloromethane has been studied for the purpose of minimizing the impact on the environment. In this case, an ether having 4 to 12 carbon atoms, a ketone having 3 to 12 carbon atoms, an ester having 3 to 12 carbon atoms, and an alcohol having 1 to 12 carbon atoms are preferable. May be. For example, a mixed solvent of methyl acetate, acetone, ethanol, and n-butanol can be mentioned. These ethers, ketones, esters and alcohols may have a cyclic structure. A compound having two or more functional groups of ether, ketone, ester and alcohol (that is, —O—, —CO—, —COO— and —OH) can also be used as a solvent.

  The details of cellulose acylate are described in paragraphs [0140] to [0195] of JP-A-2005-104148. These descriptions can be applied to the present invention. The same applies to additives such as solvents and plasticizers, deterioration inhibitors, UV absorbers (UV agents), optical anisotropy control agents, retardation control agents, dyes, matting agents, release agents, release accelerators, etc. JP-A-2005-104148 describes in detail in paragraphs [0196] to [0516], and these descriptions can also be applied to the present invention.

[Dope production method]
FIG. 1 shows a dope production line 10. The dope production line 10 includes a solvent tank 11 for storing a solvent, a mixing tank 12 for mixing the solvent and TAC, a hopper 13 for supplying TAC, and an additive for storing an additive. An agent tank 14 is provided. Furthermore, a heating device 15 for heating the swelling liquid described later, a temperature controller 16 for adjusting the temperature of the prepared dope 27, a filtering device 17, and a flash device 30 for concentrating the prepared dope 27, A filtration device 31 is also provided. A recovery device 32 for recovering the solvent and a regeneration device 33 for regenerating the recovered solvent are provided. This dope production line 10 is connected to a film production line 40 via a stock tank 41.

  The dope 27 is manufactured by the following method using the dope manufacturing line 10. The valve 18 is opened and the solvent is sent from the solvent tank 11 to the mixing tank 12. Next, an appropriate amount of TAC is sent from the hopper 13 to the mixing tank 12. In addition, a necessary amount of the additive solution is sent from the additive tank 14 to the mixing tank 12 by opening and closing the valve 19.

  The method of feeding the additive is not limited to the method of feeding it as a solution as described above. For example, when the additive is liquid at room temperature, it may be fed into the mixing tank 12 in the liquid state, and when the additive is solid, it may be fed into the mixing tank 12 using a hopper or the like. In addition, when a plurality of types of additives are added, a method in which a solution in which a plurality of types of additives are dissolved is placed in the additive tank 14 or a plurality of additive tanks are arranged in the dope production line 10. In addition, there is a method in which independent pipes are provided between the mixing tanks 12 and a solution in which the additive is dissolved is put in each additive tank.

  In the above description, the order of putting into the mixing tank 12 is the solvent (used in the meaning including the case of the mixed solvent), the TAC, and the additive. However, the order is not limited thereto. For example, a preferred amount of solvent can be fed after the TAC is metered into the mixing tank 12. Further, the additive does not necessarily need to be fed into the mixing tank 12, and may be mixed with a mixture of TAC and a solvent (hereinafter, these mixtures may also be referred to as dope) in a later step.

  As shown in FIG. 1, the mixing tank 12 includes a jacket 20 that wraps the outer surface thereof, and a first stirrer 22 that is rotated by a motor 21. However, as shown in FIG. 1, it is preferable that a second agitator 24 rotated by a motor 23 is attached to the mixing tank 12. The first stirrer 22 is preferably provided with an anchor blade, and the second stirrer 24 is preferably a dissolver type eccentric stirrer. The temperature of the mixing tank 12 is adjusted by flowing a heat transfer medium into the jacket 20. The temperature range is preferably −10 to 55 ° C. By appropriately selecting and using the first stirrer 22 and the second stirrer 24, a swelling liquid 25 in which TAC is swollen in a solvent is obtained.

  The swelling liquid 25 is sent to the heating device 15 by the pump 26. The heating device 15 is preferably a jacketed pipe, and further preferably has a configuration capable of pressurizing the swelling liquid 25. By using such a heating device 15, the dope 27 can be obtained by dissolving the solid content in the swelling liquid 25 under heating conditions or under pressure heating conditions. Hereinafter, this method is referred to as a heating dissolution method. The temperature of the swelling liquid 25 is preferably 50 to 120 ° C. A cooling dissolution method in which the swelling liquid 25 is cooled to a temperature of −100 to −30 ° C. can also be performed. By appropriately selecting such a heating dissolution method and a cooling dissolution method, TAC can be sufficiently dissolved in a solvent. After the dope 27 is brought to about room temperature by the temperature controller 16, the dope 27 is filtered by the filtering device 17 to remove impurities contained in the dope 27. The filtration filter used in the filtration device 17 preferably has an average pore diameter of 100 μm or less. The filtration flow rate is preferably 50 L / hr or more. The dope 27 after filtration is sent to the stock tank 41 in the film production line 40 via the valve 28 and stored here.

  As described above, the method of preparing the dope 27 after preparing the swelling liquid 25 requires a longer time as the concentration of TAC is increased, which may cause a problem in terms of manufacturing cost. Therefore, when the dope 27 is manufactured by such a method, the dope 27 having a target concentration can be adjusted by preparing the dope 27 having a lower concentration than the target concentration and then performing the concentration step. preferable. In this case, the dope 27 filtered by the filtering device 17 is sent to the flash device 30 through the valve 28, and a part of the solvent in the dope 27 is evaporated in the flash device 30. The solvent gas generated by the evaporation is condensed by a condenser (not shown) to become a liquid and is recovered by the recovery device 32. The recovered solvent is regenerated and reused as a solvent for dope preparation by the regenerator 33. This reuse is effective in terms of cost.

  Further, the concentrated dope 27 is extracted from the flash device 30 by the pump 34. At this time, in order to remove bubbles generated in the dope 27, it is preferable to perform a bubble removal process. Various known methods can be applied as a method for removing bubbles. For example, an ultrasonic irradiation method is mentioned. Subsequently, the dope 27 is sent to the filtering device 31 and filtered. Thereby, the foreign matter is removed from the dope 27. The temperature of the dope 27 during filtration is preferably 0 to 200 ° C. The filtered dope 27 is sent to the stock tank 41 and stored. A stirrer 61 that is rotated by a motor 60 is attached to the stock tank 41, and the dope 27 is constantly stirred by rotating the stirrer 61.

  The dope 27 can be manufactured by the above method. At this time, the TAC concentration in the dope 27 is preferably 5 to 40% by mass, more preferably 15 to 30% by mass, and particularly preferably 17 to 25% by mass. The mass ratio of the additive (mainly plasticizer) is preferably in the range of 1 to 20 when the mass of the entire solid content in the dope 27 is 100.

  In addition, about the raw material in the solution casting method which obtains a TAC film, a raw material, the additive dissolution method and addition method, the filtration method, the manufacturing method of dope, such as defoaming, from paragraph [0517] of JP-A-2005-104148 [0616] is described in detail in the paragraph. These descriptions can be applied to the present invention.

[Solution casting method]
A method for producing a film using the dope 27 produced by the above method will be described. FIG. 2 is a schematic view showing a film production line 40. However, the present invention is not limited to the form shown in FIG. The film production line 40 connected to the dope production line via the stock tank 41 includes a filtration device 42, a casting die 43, a casting band 46 stretched around rotating rollers 44 and 45, and a tenter dryer 47. Etc. are provided. Further, an ear-cutting device 50, a drying chamber 51, a cooling chamber 52, a winding chamber 53, and the like are arranged. The stock tank 41 is connected to the casting die 43 via a pump 62 and a filtration device 42.

As a material of the casting die 43, precipitation hardening type stainless steel is preferable, and its thermal expansion coefficient is preferably 2 × 10 ⁻⁵ (° C. ⁻¹ ) or less. In a forced corrosion test with an electrolyte aqueous solution, it has a corrosion resistance substantially equivalent to that of SUS316, and even when immersed in a mixture of dichloromethane, methanol, and water for 3 months, it does not cause pitting (opening) at the gas-liquid interface. Those having corrosive properties can also be used as the material of the casting die 43. In addition, it is preferable that the casting die 43 is manufactured by grinding a material that has passed one month or more after casting. Thereby, it is possible to prevent the dope 27 from flowing uniformly in the casting die 43 and causing streaks or the like in the casting film 69 described later. The finishing accuracy of the wetted surface of the casting die 43 is preferably 1 μm or less in terms of surface roughness, and the straightness is preferably 1 μm / m or less in any direction. The slit clearance of the casting die 43 can be adjusted in the range of 0.5 to 3.5 mm by automatic adjustment. About the corner | angular part of the liquid-contacting part of the lip | tip end of the casting die 43, R is 50 micrometers or less over the whole width. Moreover, it is preferable that the shear rate inside the casting die 43 is adjusted to be 1 to 5000 (1 / second).

  The width of the casting die 43 is not particularly limited, but is preferably 1.1 to 2.0 times the width of the film as the final product. Further, it is preferable to attach a temperature controller to the casting die 43 so that the temperature during film formation is maintained at a predetermined temperature, and the casting die 43 is preferably a coat hanger type. Furthermore, it is more preferable that a thickness adjusting bolt (heat bolt) is provided at a predetermined interval in the width direction of the casting die 43 and the casting die 43 is provided with an automatic thickness adjusting mechanism using a heat bolt. The heat bolt is preferably subjected to film formation by setting a profile according to a liquid feeding amount of a pump (preferably a high precision gear pump) 62 according to a preset program. Feedback control may be performed by an adjustment program based on a profile of a thickness gauge (not shown). Examples of the thickness gauge include an infrared thickness gauge, but are not particularly limited. The thickness difference between any two points in the width direction of the product film excluding the casting edge is preferably adjusted within 1 μm so that the difference between the minimum value and the maximum value in the width direction thickness is 3 μm or less. It is more preferable to adjust to 2 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 lip end of the casting die 43. A method for forming the cured film is not particularly limited, and examples thereof include ceramic coating, hard chrome plating, and a nitriding method. When using ceramics as the cured film, it can be ground and has low porosity, is not brittle and excellent in corrosion resistance, and has good adhesion to the casting die 43, while having good adhesion to the dope. Bad ones are preferred. Specific examples include tungsten carbide (WC), Al ₂ O ₃ , TiN, and Cr ₂ O ₃ , among which WC is preferable. This WC coating can be performed by a thermal spraying method.

  In order to prevent the dope 27 flowing out to the slit end of the casting die 43 from locally drying and solidifying, it is preferable to attach a solvent supply device (not shown) to the slit end. In this case, a solvent for solubilizing the dope 27 (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) is formed at both ends of the casting bead and at the end of the die slit. It is preferable to supply near the periphery of the three-phase contact line formed by the part and outside air. Supplying at 0.1 to 1.0 mL / min to each one side of the end is preferable because mixing of foreign matters into the cast film can be prevented. In addition, as a pump which supplies this liquid, it is preferable to use a pump with a pulsation rate of 5% or less.

  A casting band 46 is provided below the casting die 43 so as to span the rotating rollers 44 and 45. The rotating rollers 44 and 45 are rotated by a driving device (not shown), and the casting band 46 travels endlessly with the rotation. It is preferable that the casting band 46 can move at a moving speed, that is, a casting speed of 10 to 200 m / min. In order to set the surface temperature of the casting band 46 to a predetermined value, it is preferable that the heat transfer medium circulating device 63 is attached to the rotating rollers 44 and 45. The casting band 46 is preferably one whose surface temperature can be adjusted to -20 to 40 ° C. A heat transfer medium flow path (not shown) is formed in the rotating rollers 44 and 45 used in the present embodiment, and the heat transfer medium maintained at a predetermined temperature passes through the flow path. The temperatures of the rotating rollers 44 and 45 are maintained at a predetermined value.

  The width of the casting band 46 is not particularly limited, but it is preferable to use one having a casting width of 1.1 to 2.0 times the casting width of the dope 27, and its length is 20 to 200 m. The thickness is preferably 0.5 to 2.5 mm, and the surface is preferably polished so that the surface roughness is 0.05 μm or less. The casting band 46 is preferably made of stainless steel, and more preferably made of SUS316 so as to have sufficient corrosion resistance and strength. Moreover, it is preferable that the thickness unevenness of the entire casting band 46 is 0.5% or less.

The rotating rollers 44 and 45 can also be used directly as a support. In this case, it is preferable that the rotation unevenness is 0.2 mm or less so that the rotation can be performed with high accuracy, and the average roughness of the surfaces of the rotating rollers 44 and 45 is preferably 0.01 μm or less. Therefore, the surface of the rotating roller is subjected to chrome plating so as to have sufficient hardness and durability. In addition, it is necessary to suppress the surface defects of the support (the casting band 46 and the rotating rollers 44 and 45) to the minimum. Specifically, there are no pinholes of 30 μm or more as surface defects, and the number of pinholes of 10 μm or more and less than 30 μm is 1 / m ² or less, and the number of pinholes of less than 10 μm is 2 / m ² or less. .

  The casting die 43, the casting band 46, and the like are housed in a casting chamber 64. The casting chamber 64 is provided with a temperature control facility 65 for keeping the internal temperature at a predetermined value, and a condenser (condenser) 66 for condensing and recovering the volatile organic solvent. A recovery device 67 for recovering the condensed and liquefied organic solvent is provided outside the casting chamber 64. Further, it is preferable that a decompression chamber 68 for controlling the pressure of the back surface of the casting bead formed from the casting die 43 to the casting band 46 is disposed, and this is also used in this embodiment. .

  An air duct 70 is provided near the peripheral surface of the casting band 46. Thereby, the casting film 69 formed on the casting band 46 is dried. Details of the air duct 70 will be described later. The casting chamber 64 is provided with a roller 75 that supports a casting film 69 peeled off from the casting band 46, that is, a wet film 74.

  The crossover portion 80 is provided with a blower 81, and the crusher 90 for finely cutting the scraps on the side end (ear) of the cut film 82 is provided on the ear clip device 50 downstream of the tenter dryer 47. It is connected.

  The drying chamber 51 is provided with a number of rollers 91, and an adsorption / recovery device 92 for adsorbing / recovering the solvent gas generated by evaporation is attached. In FIG. 2, the cooling chamber 52 is provided downstream of the drying chamber 51, but a humidity control chamber (not shown) may be provided between the drying chamber 51 and the cooling chamber 52. Further, a forced static elimination device (static elimination bar) 93 for adjusting the charged voltage of the film 82 to a predetermined range (for example, −3 to +3 kV) is provided downstream of the cooling chamber 52. In FIG. 2, the forced static eliminating device 93 is illustrated on the downstream side of the cooling chamber 52, but is not limited to this installation position. Furthermore, in this embodiment, a knurling roller 94 for applying knurling to both edges of the film 82 by embossing is appropriately provided downstream of the forced static eliminating device 93. Inside the take-up chamber 53, a take-up roller 95 for taking up the film 82 and a press roller 96 for controlling the tension during the take-up are provided.

  As shown in FIG. 3, in the vicinity of the casting film 69 immediately after formation, that is, immediately downstream of the casting die 43 and in the vicinity of the surface side where the casting film 69 of the casting band 46 is formed, An air duct 70 is provided for sending dry air to volatilize the solvent of the casting film 69. A blowing controller (not shown) for independently controlling each blowing condition such as air volume, wind temperature, humidity, and the like, and a wind controlled by the blowing controller are fed into the blowing duct 70 into the blowing duct 70. And a blower (not shown). The duct body 71 of the blower duct 70 includes a blower port 71 a that covers the entire width of the casting film 69 and a plurality of rectifying fins 100 for partitioning the blower port 71 a into a plurality of areas in the width direction of the casting band 46. Have. The rectifying fin 100 is used as a first rectifying member that rectifies the drying air from the air blowing port 71 a and sends it in parallel to the casting band 46. Thereby, it can suppress that unevenness | corrugation arises on the casting film 69. FIG. The duct main body 71 further includes a windproof plate 101 as a windproof member for suppressing the accompanying wind caused by the blowing.

  FIG. 4 is a schematic view of the duct body 71. The substantially box-shaped duct body 71 is provided so that both side members 71 b are above both side edges of the casting film 69 and perpendicular to the casting band 46. A large number of grooves 70e extending in the running direction of the casting band 46 are formed on the inner surfaces of the lower member 71c and the upper member 71d, and a thin plate-like rectifying fin is formed between the grooves 70e and 70e. 100 is fitted, and the rectifying fins 100 are provided perpendicular to the casting band 46.

  Both end members 71b are provided with a windproof plate 101 as a windproof member. A distance C1 (mm) from the windbreak plate 101 to the non-casting band 46 surface side of the casting film 69 is preferably 1 to 30 mm. More preferably, it is 3-27 mm, Most preferably, it is 5-25 mm. Thereby, since the accompanying air generated along with the drying air from the air blowing port 71a can be suppressed, the casting film 69 can be dried without causing unevenness. When C1 is less than 1 mm, the casting film 69 and the duct main body 71 are very close to each other, so that the dry air sent out from the air blowing port 71a strikes the casting film 69, and a large amount of unevenness occurs. End up. On the other hand, when C1 is larger than 30 mm, the duct main body 71 and the casting film 69 are too far away, so that the accompanying air cannot be suppressed and the wind flow may be disturbed. Unevenness unevenness may occur on the surface of the casting film 69. The windbreak plate 101 is provided with a shift mechanism (not shown) that can be moved up and down. Thereby, the position of the wind-proof board 101 in the up-down direction can be adjusted and determined arbitrarily. When the distance from the lower end of the windbreak plate 101 to the support (in the present embodiment, the casting band 46) is CA, and the thickness of the casting film 69 is CB, C1 is a length determined by CA-CB. That's it.

  The distance C2 (mm) between the duct body 71 and the cast film 69 is preferably 1 to 300 mm. More preferably, it is 2-50 mm, Most preferably, it is 5-200 mm. As a result, the drying air sent out from the air blowing port 71a does not stay in the lower part of the air blowing duct 70, and the functions of the rectifying fins 100 and the windbreak plate 101 are fully exhibited, and the drying air parallel to the casting film 69 is sent out. be able to. When C2 is larger than 300 mm, the casting membrane 69 and the duct body 71 are too far away, which is not preferable because it is necessary to increase the wind speed of the drying air. On the other hand, when C2 is less than 1 mm, the above-described range of C1 cannot be satisfied. In addition, since the drying air from the air blowing port 71a hits the casting film 69 strongly, there may be a problem that a large amount of oblique unevenness occurs on the surface of the casting film 69.

  By changing the groove 70e into which the rectifying fin 100 is fitted, the interval C3 (mm) between the rectifying fins 100 can be adjusted. The interval C3 is preferably 30 to 80 mm, more preferably 35 to 75 mm, and particularly preferably 40 to 70 mm. Thereby, it can rectify | straighten more and can send out dry wind from the ventilation port 71a. When C3 is larger than 80 mm, the rectifying effect is inferior because the number of areas formed by dividing the inside of the air blowing port 71a is small. On the other hand, when C3 is less than 30 mm, there is almost no change in the rectification effect even when C3 is about 30 mm. In addition, since a great number of rectifying fins 100 are required, only labor and equipment costs are increased.

  Moreover, it is preferable that the lower end of the windbreak plate 101 is extended below the lower member 71 c of the duct body 71. It is preferable that the length L1 (mm) of the windbreak plate 101 protruding toward the casting film 69 is 10 to 35 mm. More preferably, it is 8-33 mm, Most preferably, it is 6-30 mm. Thereby, the effect | action of the windbreak board 101 of suppressing an accompanying wind can be expressed effectively. When L1 is larger than 35 mm, wind may stay in a region surrounded by the lower member 71c and the windbreak plate 101, which is not preferable because the flow of the drying air may be disturbed. On the other hand, when L1 is less than 10 mm, since the length of the windbreak plate 101 protruding downward is too short, the windbreak effect by the windbreak plate 101 may not be obtained.

  The air is blown from the air blowing port 71a so that the drying air flows in the entire width of the casting film 69. Therefore, the width W1 (m) of the duct body 71 in the width direction of the casting band 46 is preferably set to a value equivalent to the width W2 (m) of the casting film 69. In addition, the value of W1, W2 is not specifically limited, It can set suitably.

  Dry air is sent out from the blower port 71 to the cast film 69 immediately after the formation. This “immediately after formation” means when the amount of residual solvent in the cast film 69 is 300% by weight or more. As described above, when the rectified drying air is sent out while the amount of the residual solvent in the casting film 69 is large, that is, while the drying of the casting film 69 hardly proceeds, the occurrence of uneven unevenness can be further suppressed. it can. In the case where the residual solvent amount of the casting film 69 is less than 300%, a part of the casting film 69 has already been dried, and unevenness may occur on the surface thereof. For this reason, it is not preferable to proceed with drying in such a state because unevenness will remain when a film product is produced. The amount of the residual solvent is based on the dry amount. When the film weight at the time of sampling is x and the weight after the sampling film is dried is y, {(xy) / y} × 100 Is a value calculated by.

  The materials of the rectifying fins 100 and the windbreak plate 101 are not particularly limited. For example, a plastic plate or a metal plate made of stainless steel or the like may be used. In this embodiment, although the air duct 70 which divided the inside of the ventilation port 71a with the some rectification fin 100 was shown, if it is a form which has a some area | region which can function as a ventilation port, it applies to this invention. be able to. For example, you may use what integrated and combined the housing | casing which has the function of a some air blower as a ventilation duct.

  In this embodiment, one blower duct 70 is arranged immediately downstream of the casting die 43, but the arrangement location and the number of arrangements are such that the residual solvent amount of the casting film 69 is 300% by weight or more. The area is not particularly limited. For example, a plurality may be arranged in series along the traveling path of the casting band 46. When a plurality of air ducts 70 are arranged in this manner, the casting film 69 can be dried while further promoting the volatilization of the solvent in the casting film 69 and preventing unevenness of unevenness.

  Next, an example of a method for manufacturing the film 82 using the above-described film manufacturing line 40 will be described below. However, the present invention is not limited to the embodiment shown here.

The dope 27 is always made uniform by the rotation of the stirrer 61. The dope 27 can be mixed with additives such as a plasticizer and an ultraviolet absorber even during the stirring. After the dope 27 is sent to the filtration device 42 by the pump 62 and filtered, the dope 27 is cast from the casting die 43 onto the casting band 46. The driving of the rotating rollers 44 and 45 is preferably adjusted so that the tension generated in the casting band 46 is 10 ⁴ to 10 ⁵ N / m. Further, the relative speed difference between the casting band 46 and the rotary rollers 44 and 45 is adjusted to be 0.01 m / min or less.

  The speed fluctuation of the casting band 46 is preferably 0.5% or less, and the meandering in the width direction when the casting band 46 rotates once is preferably 1.5 mm or less. In order to control the meandering, a detector (not shown) for detecting the positions of both ends of the casting band 46 is provided, and feedback control is performed by a position controller (not shown) of the casting band 46 based on the measured value. More preferably, the position of the casting band 46 is adjusted. The casting band 46 immediately below the casting die 43 is preferably adjusted so that the positional fluctuation in the vertical direction accompanying the rotation of the rotary roller 55 is 200 μm or less. Further, the temperature of the casting chamber 64 is preferably set to −10 to 57 ° C. by the temperature control equipment 65. The solvent evaporated inside the casting chamber 64 is recovered by the recovery device 67 and then regenerated and reused as a dope preparation solvent.

  A casting bead is formed from the casting die 43 to the casting band 46, and a casting film 69 is formed on the casting band 46. The temperature of the dope 27 at the time of casting is preferably −10 to 57 ° C. Further, in order to stabilize the casting bead, the back surface of the casting bead is preferably controlled to a desired pressure value by the decompression chamber 68. The back surface of the bead is preferably decompressed in the range of −2000 to −10 Pa than the front surface. Further, it is preferable that a jacket (not shown) is attached to the decompression chamber 68 and the temperature is controlled so that the internal temperature is kept at a predetermined temperature. The temperature of the decompression chamber 68 is not particularly limited, but is preferably set to be equal to or higher than the condensation point of the organic solvent used. In order to keep the shape of the casting bead as desired, it is preferable to attach a suction device (not shown) to the edge portion of the casting die 43. The edge suction air volume is preferably in the range of 1 to 100 L / min. Drying air is applied to the casting film 69 that moves along with the running of the casting band 46 by the air duct 70 to promote evaporation of the solvent.

  After the casting film 69 has a self-supporting property, it is peeled off from the casting band 46 as a wet film 74 and then supported by a roller 75. It is preferable that the amount of residual solvent at the time of stripping is 20 to 250% by mass based on the solid content. Next, the paper is fed into a transfer section 80 provided with a large number of rollers, conveyed while being supported by the rollers, and then fed into a tenter dryer 47. In the transfer part 80, the drying of the wet film 74 is advanced by sending the drying air of desired temperature from the air blower 81. FIG. At this time, the temperature of the drying air is preferably 20 to 250 ° C. In the crossing section 80, the wet film 74 can be given draw tension by making the rotation speed of the downstream roller faster than the rotation speed of the upstream roller.

  Wet film 74 is fed into tenter dryer 47. In the tenter dryer 47, both ends of the wet film 74 are gripped by clips and dried while being conveyed. At this time, it is preferable that the interior of the tenter dryer 47 is partitioned into temperature zones, and the drying conditions are appropriately adjusted for each partition. Further, the wet film 74 can be stretched in the width direction using the tenter dryer 47. As described above, in the transfer section 80 and / or the tenter dryer 47, it is preferable that the wet film 74 is stretched by 0.5 to 300% in at least one of the casting direction and the width direction.

  The wet film 74 is dried to a predetermined residual solvent amount by the tenter dryer 47 and then sent to the downstream side as a film 82. At this time, both edges of the both ends of the film 82 are cut by the edge-cutting device 50. The cut side end portion is sent to a crusher 90 by a cutter blower (not shown) and crushed into chips. Since this chip can be reused for dope preparation, it is effective in terms of manufacturing cost. In addition, although the cutting process of the both ends of the film 82 can be omitted, it is preferable to carry out any of the processes from the casting process to the winding process of the film 82.

  The film 82 from which both end portions have been cut and removed is fed into the drying chamber 51 and further dried. Although the temperature in the drying chamber 51 is not specifically limited, It is preferable that it is the range of 50-160 degreeC. In the drying chamber 51, the film 82 is conveyed while being wound around the roller 91. The solvent gas generated by evaporation here is adsorbed and recovered by the adsorption recovery device 92. Thus, the air from which the solvent component has been removed is blown again as dry air inside the drying chamber 51. The drying chamber 51 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 50 and the drying chamber 51 to preliminarily dry the film 82, the temperature of the film 82 in the drying chamber 51 can be prevented from rapidly increasing. Therefore, the occurrence of the shape change of the film 82 can be further suppressed.

  The film 82 is cooled to approximately room temperature in the cooling chamber 52. A humidity control chamber (not shown) may be provided between the drying chamber 51 and the cooling chamber 52, and air adjusted to a desired humidity and temperature can be blown to the film 82 in the humidity control chamber. Is preferred. Thereby, it is possible to suppress the occurrence of curling of the film 82 and the occurrence of winding failure when winding.

  Further, the charged voltage while the film 82 is being conveyed by the forced static eliminator (static neutralization bar) 93 is set within a predetermined range (for example, −3 to +3 kV). FIG. 2 illustrates an example provided on the downstream side of the cooling chamber 52, but the position is not limited thereto. Further, it is preferable to provide a knurling roller 94 and to impart knurling to both edges of the film 82 by embossing. In addition, it is preferable that the unevenness | corrugation of the knurled location is 1-200 micrometers.

  Finally, the film 82 is taken up by the take-up roller 95 in the take-up chamber 53. At this time, it is preferable to wind up while applying a desired tension with the press roller 96. More preferably, the tension is gradually changed from the start to the end of winding. The film 82 to be wound is preferably at least 100 m in the longitudinal direction (casting direction). Moreover, it is preferable that the width | variety of the film 82 is 600 mm or more, and it is more preferable that it is 1400-1800 mm. The present invention is also effective when it is larger than 1800 mm. The present invention is also applied when manufacturing a thin film having a thickness of 15 to 100 μm.

  In the present embodiment, a form in which a single plate is used as the windproof plate 101 is shown, but the shape is not particularly limited as long as it is arranged so as to satisfy C1 to C3 described above. Another example of the windbreak plate 101 is a windbreak plate 112 (L-shaped) having an L-shaped lower end as shown in FIG. The L-shaped windbreak plate 112 may be formed by combining a plurality of two plates, or may be formed by a single plate. When such an L-shaped windbreak plate 112 is installed on both side members 71b of the air duct 70, the pressure loss of the flowing wind can be increased by the protruding portions 112a protruding in parallel with the casting band 46. Accompanied wind generated with the air blowing from the air blowing port 71a can be suppressed. Hereinafter, the air duct 70 provided with the L-shaped windbreak plate 112 is referred to as an L-shape. In addition, the same member as FIG. 4 attaches | subjects a same sign, and abbreviate | omits description. Further, the groove 70e is omitted to avoid complexity of the drawing.

  The length L2 (mm) of the windbreak plate 112 protruding in the direction parallel to the casting band 46 is preferably 2 to 20 mm. More preferably, it is 5-19 mm, Most preferably, it is 10-18 mm. However, when L2 is larger than 20 mm, the pressure loss becomes too large, and the flow of the drying air from the air blowing port 71a is disturbed. On the other hand, when L2 is less than 2 mm, the length of the windbreak plate protruding in parallel with the casting band 46 is too short, so that the pressure loss cannot be increased and the accompanying wind cannot be suppressed. The windbreak plate 112 is provided with a shift mechanism, which can be moved up and down on both side members 71b.

  Moreover, as shown in FIG. 6, the outstanding rectification effect can be acquired also by installing the rectification member (2nd rectification member) 122b in the lower member 71c of the ventilation port 70. As shown in FIG. The air duct 70 having such a configuration is referred to as a lower installation type. In addition, in order to avoid the complexity of a figure, illustration of the groove | channel 70e inside the ventilation port 71a and the rectifying fin 100 is abbreviate | omitted.

  The air duct 70 has a single windbreak plate 122a on each side member 71b and a plurality of rectifying members 122b on the lower member 71c. In this manner, when a plurality of rectifying members 122b are installed on the lower member 71c, the wind flowing between the lower member 71c and the casting band 46 can be rectified. As the rectifying member 122b, a rectifying fin used when installed in the air outlet 71a may be used. Hereinafter, the air duct 70 to which such a rectifying member 122b is attached is referred to as a lower member installation type.

  The shape and material of the rectifying member 122b are not particularly limited. However, the height H1 (mm) of the rectifying member 122b is preferably 10 to 20 mm. More preferably, it is 11-19 mm, Most preferably, it is 12-18 mm. If H1 is too large, particularly if it is larger than 20 mm, the flow of wind on the surface of the casting film 69 may be hindered. On the other hand, when H1 is less than 10 mm, the height of the second windbreak plate 122b is too low, so that the rectifying effect is inferior.

  Further, the rectifying member 122b is provided with a shift mechanism (not shown), and can thereby be freely moved back and forth to arbitrarily adjust the position of the rectifying member 122b. At this time, it is preferable to adjust the length L2 (mm) protruding from the front surface of the air blowing port 71a to be 10 to 100 mm. More preferably, it is 15-95 mm, Most preferably, it is 20-90 mm. Thereby, the outstanding rectification effect by the rectification member 122b can be acquired. The depth of the rectifying member 122b is not particularly limited as long as it can be arranged to satisfy L3.

  The rectifying member 122b is preferably arranged so that the interval C4 is 50 to 400 mm in the lower member 71c of the air duct 70. More preferably, it is 55-395 mm, Most preferably, it is 60-390 mm. Thereby, the rectification effect in the vicinity of the lower member 71c can be further increased. When the interval C4 is larger than 400 mm, the number of rectifying members 122b provided on the lower member 71c is too small, and the rectifying effect is inferior. On the other hand, when the distance C4 is less than 50 mm, the rectification effect is not improved even when compared to the case where C4 is about 50 mm. Further, since the number of the rectifying members 122b to be used is large, the equipment cost increases, which is not preferable. The number of the rectifying members 122b is not particularly limited as long as the distance C4 is appropriately selected according to the length of the lower member 71c.

  In the solution casting method of the present invention, when casting the dope, two or more kinds of dopes can be simultaneously laminated or sequentially laminated. Furthermore, you may combine both casting. When performing simultaneous lamination and co-casting, a casting die to which a feed block is attached may be used, or a multi-manifold casting die may be used. It is preferable that at least one of the thickness of the layer on the air surface side and the thickness of the layer on the support side is 0.5% to 30% of the thickness of the entire film. Furthermore, when performing simultaneous lamination co-casting, it is preferable that the high-viscosity dope is wrapped with the low-viscosity dope when the dope 27 is cast from the die slit to the support. Moreover, when performing simultaneous lamination | stacking co-casting, it is preferable that the dope which contact | connects an external field has a larger alcohol composition ratio than an internal dope among the casting beads formed from a die slit to a support body.

  From casting die, support structure, co-casting, peeling method, stretching, drying conditions for each process, handling method, curl, winding method after flatness correction, solvent recovery method, film recovery method, etc. This is described in detail in paragraphs [0617] to [0889] of Kai 2005-104148. These descriptions can be applied 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 [0112] to [0139] of JP-A-2005-104148. These descriptions can be applied 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. Furthermore, it is preferable to use this cellulose acylate film as a base film as a functional material provided with other functional layers. 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 layer, at least it is preferable that a kind of surfactant 0.1 to 1000 mg / ^{m 2} containing, it is preferable that at least one of a slip agent 0.1 to 1000 mg / ^{m 2} containing. Further, the functional layers, at least it is preferable that a kind of matting agent 0.1 to 1000 mg / ^{m 2} containing preferably contain at least one 1 to 1000 mg / ^{m 2} containing an antistatic agent.

  A method for imparting a surface-treated functional layer to a cellulose acylate film in order to realize various functions and properties is described in detail in paragraphs [0890] to [1087] of JP-A-2005-104148. It is included. These descriptions can be applied to the present invention.

(Use)
The cellulose acylate film is particularly useful as a polarizing plate protective film. Usually, two polarizing plates each having a cellulose acylate film bonded to a polarizer are bonded to a liquid crystal layer to produce a liquid crystal display device. However, the arrangement of the liquid crystal layer and the polarizing plate is not limited, and various known arrangements may be used. Japanese Patent Application Laid-Open No. 2005-104148 describes in detail TN type, STN type, VA type, OCB type, reflective type, and other examples of liquid crystal display devices. This description can be applied to the present invention. The application also describes an optically anisotropic layer and a cellulose acylate film provided with antireflection and antiglare functions. Furthermore, a use as an optical compensation film having a biaxial cellulose acylate film imparted with appropriate optical performance is also described. This can also be used as a polarizing plate protective film. Details are described in paragraphs [1088] to [1265] of JP-A-2005-104148. These descriptions can be applied to the present invention.

  Moreover, the cellulose triacetate film (TAC film) which is excellent in an optical characteristic by this invention can be obtained. This TAC film can be used as a polarizing plate protective film or a base film of a photographic photosensitive material. Furthermore, it can also be used as an optical compensation film for improving the viewing angle dependency of a liquid crystal display device for television applications. In particular, it is effective for applications that also serve as a protective film for a polarizing plate. Therefore, it is used not only for the conventional TN mode but also for the IPS mode, OCB mode, VA mode, and the like. In addition, you may comprise a polarizing plate using the said film for polarizing plate protective films.

  Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to these examples. The manufacturing method and manufacturing conditions will be described in detail only in the first embodiment.

  Next, examples of the present invention will be described. The formulation for preparing the dope used for film production is shown below.

[composition]
Cellulose triacetate (substitution degree 2.84, viscosity average polymerization degree 306, water content 0.2 mass%, viscosity 6 mass% in dichloromethane solution 315 mPa · s, average particle diameter 1.5 mm with standard deviation 0.5 mm Some powders) 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 plasticizer A (triphenyl phosphate) 7.6 parts by mass Plasticizer B (diphenyl phosphate) 3.8 parts by mass UV agent a: 2 (2′-hydroxy-3 ′, 5′-di-tert-butylphenyl) benzotriazole 0.7 part by mass UV agent b: 2 ( 2'-hydroxy-3 ', 5'-di-tert-amylphenyl) -5
Chlorbenzotriazole 0.3 parts by mass Citric acid ester mixture (citric acid, monoethyl ester, diethyl ester, triethyl ester mixture) 0.006 parts by mass fine particles (silicon dioxide (average particle size 15 nm), Mohs hardness about 7) 0. 05 parts by mass

[Cellulose triacetate]
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, free acetic acid 40 ppm, and sulfate ions. Was 15 ppm. The 6-position acyl substitution degree was 0.91, and 32.5% of all acetyl groups were acetyl groups substituted with the 6-position hydroxyl group. Moreover, the acetone extraction part which extracted this TAC with acetone was 8 mass%, and the weight average molecular weight / number average molecular weight ratio was 2.5. The obtained TAC has a yellow index of 1.7, a haze of 0.08, a transparency of 93.5%, a Tg (glass transition temperature; measured by DSC) of 160 ° C., and a crystallization heat generation of 6. It was 4 J / g. This TAC is synthesized using cellulose collected from cotton as a raw material. In the following description, this is called cotton raw material TAC.

  A dope 27 was prepared using the dope production line 10 shown in FIG. The plurality of solvents were mixed and stirred well in a 4000 L stainless steel mixing tank 12 having a stirring blade to obtain a mixed solvent. In addition, as each raw material of a solvent, that whose water content is 0.5 mass% or less was used. Next, TAC flaky powder was gradually added from the hopper 13. The TAC powder is put into the mixing tank 12 and is initially stirred at a peripheral speed of 1 m / sec. With a dissolver-type eccentric agitator 24 that stirs at a peripheral speed of 5 m / sec and a stirrer 22 having an anchor blade on the central axis. Dispersed under for 30 minutes. The temperature at the start of dispersion was 25 ° C., and the final temperature reached 48 ° C. Furthermore, the additive solution prepared in advance was fed from the additive tank 14 to the mixing tank 12 so that the total amount would be 2000 kg while adjusting the liquid feed amount with the valve 19. After finishing the dispersion of the additive solution, the high speed stirring was stopped. And the peripheral speed of the anchor wing | blade of the stirrer 22 was made into 0.5 m / sec, and also it stirred for 100 minutes, the TAC flakes were swollen and the swelling liquid 25 was obtained. Until the end of swelling, the inside of the mixing tank 12 was pressurized to 0.12 MPa with nitrogen gas. At this time, the inside of the mixing tank 12 had an oxygen concentration of less than 2 vol%, and kept a problem-free state in terms of explosion protection. Moreover, the water content in the swelling liquid 25 was 0.3 mass%.

  The swelling liquid 25 was fed from the mixing tank 12 to the jacketed pipe 15 using the pump 26. Using a jacketed pipe as the heating device 15, the swelling liquid 25 was heated to 50 ° C., and further heated to 90 ° C. under a pressure of 2 MPa to be completely dissolved. At this time, the heating time was 15 minutes. Next, the temperature of this solution was lowered to 36 ° C. by the temperature controller 16 and then passed through a filtration device 17 having a filter with a nominal pore diameter of 8 μm to obtain a dope (hereinafter referred to as pre-concentration dope). The primary pressure in the filtration device 17 was 1.5 MPa, and the secondary pressure was 1.2 MPa. Filters and piping exposed to high temperatures were made of Hastelloy (trade name) alloy.

This pre-concentration dope was flash-evaporated in a flash apparatus 30 at 80 ° C. and normal pressure to obtain a dope 27. The evaporated solvent was recovered with a condenser. The solid concentration of the dope 27 after the flash was 21.8% by mass. The condensed solvent was recovered by the recovery device 32, regenerated by the regenerator 33, then sent to the solvent tank 11 and reused as a dope preparation solvent. In the recovery device 32 and the regeneration device 33, distillation or dehydration was performed. The flash tank of the flash device 30 was provided with a stirrer (not shown) having an anchor blade on the stirring shaft, and the dope flashed at a peripheral speed of 0.5 m / second was stirred and defoamed. The temperature of the dope 27 in this flash tank was 25 ° C., and the average residence time of the dope in the tank was 50 minutes. The shear viscosity of the dope 27 collected and measured at 25 ° C. was 450 Pa · s at a shear rate of 10 (seconds ⁻¹ ).

  Next, the dope 27 was irradiated with weak ultrasonic waves to remove bubbles, and then passed through the filtration device 31 while being pressurized to 1.5 MPa using the pump 34. In the filtering device 31, first, a sintered fiber metal filter having a nominal pore diameter of 10 μm was passed, and then a sintered fiber filter having a nominal pore diameter of 10 μm was passed. At this time, the primary side pressure was 1.5 MPa and 1.2 MPa, and the secondary side pressure was 1.0 MPa and 0.8 MPa. After filtration, the dope 27 whose temperature was adjusted to 36 ° C. was sent and stored in a 2000 L stainless steel stock tank 41. In the stock tank 41, stirring was always performed at a peripheral speed of 0.3 m / sec by a stirrer 61 having an anchor blade on the central axis.

  The film 82 was manufactured using the film manufacturing line 40 shown in FIG. The dope 27 was sent from the stock tank 41 to the filtration device 42 using a high-precision gear pump 62 having a function of increasing the pressure on the primary side. At this time, feedback control for the upstream side of the gear pump 62 was performed by an inverter motor so that the primary pressure was 0.8 MPa. The gear pump 62 has a volumetric efficiency of 99.2% and a discharge rate variation rate of 0.5% or less. The discharge pressure was 1.5 MPa. After passing the dope 27 through the filtration device 42, the dope 27 was fed to the casting die 43.

  The dope 27 is cast from the discharge port of the casting die 43 while adjusting the flow rate so that the width is 1.8 m and the film thickness of the dried film is 80 μm and the casting width of the dope 27 is 1700 mm. did. At this time, the casting speed was 20 m / min. Further, a jacket (not shown) was attached to the casting die 43, and a heat transfer medium was supplied into the casting die 43 to adjust the temperature of the dope 27 to 36 ° C. During the film formation, the piping through which the casting die 43 and the dope 27 pass was all kept at 36 ° C. The casting die 43 is a coat hanger type die, and thickness adjusting bolts are provided at a pitch of 20 mm, and a die having an automatic thickness adjusting mechanism using a heat bolt is used. This heat bolt can also set a profile according to the liquid feed amount of the gear pump 62 by a preset program, and is fed back by an adjustment program based on the profile of an infrared thickness meter (not shown) installed in the film production line 40. The thing which has the performance which can also be controlled was used. The film excluding the end 20 mm has a thickness difference of 1 μm or less at any two points 50 mm apart, the thickness variation in the width direction is 3 μm / m or less, and the total thickness is ± 1.5% or less. Adjusted as follows.

  A decompression chamber 68 was installed on the primary side of the casting die 43. The decompression degree of the decompression chamber 68 was adjusted so as to produce a pressure difference of 1 to 5000 Pa before and after the casting bead according to the casting speed. Moreover, the pressure difference on both sides of the casting bead was set so that the length of the casting bead was 20 to 50 mm. The decompression chamber 68 was provided with a mechanism that can be set to a temperature higher than the condensation temperature of the gas around the casting portion. A labyrinth packing (not shown) was provided on the front and back surfaces of the bead at the discharge port of the casting die 43, and openings were provided at both ends of the discharge port. Further, an edge suction device (not shown) for adjusting the disturbance of both edges of the casting bead was attached to the casting die 43.

As the material of the casting die 43, precipitation hardening type stainless steel having a thermal expansion coefficient of 2 × 10 ⁻⁵ (° C. ⁻¹ ) or less was used. The finishing accuracy of the liquid contact surface of the casting die 43 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. A WC (tungsten carbide) coating was applied to the lip end of the casting die 43 by a thermal spraying method to provide a cured film. As for the corner portion of the wetted surface, R processed so as to be 50 μm or less over the entire width of the slit was used.

  In order to prevent the dope 27 to be cast from being locally dried and solidified at the discharge port of the casting die 43, 86.5 parts by mass of dichloromethane and 13 parts by mass of acetone are used as a solvent for solubilizing the dope 27. The mixed solvent A was prepared by mixing 0.5 parts by mass of 1-butanol and 0.5 ml / min was supplied to the interface between the both side ends of the casting bead and the discharge port. At this time, the pulsation rate of the pump supplying the mixed solvent A was set to 5% or less. Further, the pressure on the back side of the casting bead was reduced by 150 Pa from the front side by the decompression chamber 68. The decompression chamber 68 was provided with a jacket (not shown), and the temperature was adjusted by supplying a heat transfer medium adjusted to 35 ° C. into the jacket. The edge suction device is capable of adjusting the edge suction air volume so as to be in the range of 1 to 100 L / min, and in the present embodiment, this is in the range of 30 to 40 L / min. It was adjusted.

The dope 27 was cast from the casting die 43 on the casting band 46 installed in the casting chamber 64 having wind pressure fluctuation suppressing means (not shown). As the casting band 46, an endless band made of SUS316 was used which was polished to have a width of 2.1 m, a length of 70 m, a thickness of 1.5 mm, and a surface roughness of 0.05 μm or less. The thickness unevenness of the entire casting band 46 was 0.5% or less. The casting band 46 was driven by the two rotating rollers 44 and 45. At this time, the tension in the conveying direction of the casting band 46 is 1.5 × 10 ⁵ N / m ² , and the relative speed difference between the casting band 46 and the rotary rollers 44 and 45 is 0.01 m / min or less, The speed fluctuation of the casting band 46 was adjusted to 0.5% or less. Further, both end positions of the casting band 46 were detected, and the meandering in the width direction of one rotation was controlled to be 1.5 mm or less. The positional fluctuation in the vertical direction between the die lip tip and the casting band 46 immediately below the casting die 43 was set to 200 μm or less.

As the rotating rollers 44 and 45, those capable of feeding a heat transfer medium therein were used so that the temperature of the casting band 46 could be adjusted. A 40 ° C. heat transfer medium was passed through the rotating roller 44 for drying. On the other hand, a heat transfer medium at 5 ° C. was passed through the rotating roller 45. The surface temperature of the central part of the casting band 46 immediately before casting was 15 ° C., and the temperature difference between both side ends was 6 ° C. or less. The casting band 46 has no pinholes of 30 μm or more, the pinholes of 10 μm to 30 μm are 1 piece / m ² or less, and the pinholes of less than 10 μm are 2 pieces / m ² or less. No endless band used. The temperature of the casting chamber 64 was kept at 35 ° C. by the temperature control equipment 65. The casting film 69 on the casting band 46 was first dried by sending a drying air flowing parallel to the casting film 69. The overall heat transfer coefficient from the dry air to the cast film 69 was 24 kcal / (m ² · hour · ° C.).

  A blower duct 70 was provided as a blower upstream of the upper part of the casting band 46 (see FIG. 3). At this time, as shown in FIG. 4, as the air duct 70, a rectifying fin 100 made of stainless steel is provided in the air outlet 71a so that the distance C3 is 50 mm. Further, both side members 71b of the air duct 70 are provided. A single windproof plate 101 was installed. At this time, it was installed such that C1 (mm) was 5 mm. Further, the casting film 69 was dried by sending a drying air of 135 ° C. out of the air blowing port 71a. Note that the oxygen concentration in the dry atmosphere on the casting band 43 was maintained at 5 vol% by replacing air with nitrogen gas. The solvent in the casting chamber 64 was condensed and recovered by setting the outlet temperature of the condenser (condenser) 66 to −10 ° C.

When the amount of residual solvent in the cast film 69 reached 50% by weight, the film was peeled off as a wet film 74 from the cast band 46 and supported by the roller 75. The stripping tension is 1 × 10 ² N / m ² and the stripping speed (stripping roller draw) is 100.1 to 110% with respect to the speed of the casting band 46 in order to suppress stripping failure. Adjusted within the range. The surface temperature of the peeled wet film 74 was 15 ° C. The solvent gas generated by drying was condensed and liquefied by a condenser 66 adjusted to −10 ° C. and then recovered by a recovery device 67, and the solvent was removed so that the water content was 0.5% or less. The drying air from which the solvent was removed was heated again and reused as drying air. The wet film 74 was conveyed through the roller of the crossing section 80 and sent to the tenter dryer 47. In the transfer section 80, a drying air of 40 ° C. was blown from the blower 81 to the wet film 74 and dried while applying a tension of about 30 N to the longitudinal direction of the wet film 74.

  In the tenter-type dryer 47, the wet film 74 was conveyed while being stretched in the width direction in a state where both end portions of the wet film 74 were held by clips. The clip was conveyed by a chain and cooled by supplying a heat transfer medium at 20 ° C. The tenter dryer 47 was divided into three zones, and the drying air temperature in each zone was set to 90 ° C., 110 ° C., and 120 ° C. from the upstream side. The gas composition of the drying air was set to a saturated gas concentration at −10 ° C. At the outlet of the tenter dryer 47, drying was performed by adjusting the conditions of the drying zone so that the amount of residual solvent in the film 82 was 7% by mass. When the width of the wet film 74 before stretching was 100%, the film was stretched so that the width after stretching was 103%. The stretching ratio (tenter driven draw) from the roller 75 to the inlet of the tenter dryer 47 was 102%.

  The stretching rate inside the tenter dryer 47 is 10% or less in the difference between each substantial stretching rate at any two points at a position 10 mm or more away from the biting start position by the clip, and any 2 at 20 mm apart. The difference in the stretching ratio of points was 5% or less. The ratio of the length from the clip clamping start position to the clamping release position with respect to the length from the inlet to the outlet of the tenter dryer 47 was 90%. The solvent evaporated in the tenter dryer 47 was condensed and liquefied at a temperature of −10 ° C. by collecting a condenser (condenser) and setting its outlet temperature to −8 ° C. This condensed solvent was reused after adjusting the water content to be 0.5% by mass or less. Then, the film was sent out from the tenter dryer 47 as a film 82.

Within 30 seconds from the exit of the tenter dryer 47, the ears 50 mm on both sides of the film 82 were cut using an NT-type cutter as the ear-cutting device 50. At this time, the cut ears were blown to a crusher 90 by a cutter blower (not shown) and crushed into chips of about 80 mm ² on average, and this chip was used again as a dope preparation raw material. The air in the tenter dryer 47 was replaced with nitrogen gas, and the oxygen concentration in the dry atmosphere was maintained at 5 vol%. In addition, the film 82 was preheated in a predrying chamber (not shown) to which drying air at 100 ° C. was supplied before drying at a high temperature in the drying chamber 51 described later.

  The film 82 was dried at a high temperature in the drying chamber 51. The drying chamber 51 was divided into four, and drying air of 120 ° C., 130 ° C., 130 ° C., and 130 ° C. was sent from a blower (not shown) from the upstream side. The conveying tension of the film 82 by the roller 91 was set to 100 N / m, and the film was dried for about 10 minutes until the residual solvent amount finally reached 0.3% by mass. At this time, the wrap angle of the roller 91 (film winding center angle) was 90 degrees and 180 degrees (exaggerated in FIG. 2). The material of the roller 91 was made of aluminum or carbon steel, and the surface was hard chrome plated. Moreover, the surface shape of the roller 91 used was a flat one or a mat formed by blasting. Film position fluctuations due to the rotation of the roller 91 were all 50 μm or less. The roller deflection at a tension of 100 N / m was selected to be 0.5 mm or less.

  The solvent gas contained in the drying air was adsorbed and recovered using an adsorption recovery device 92. The adsorbent used here was activated carbon, and desorption was performed using dry nitrogen. The collected solvent was reused as a dope preparation solvent after adjusting the water content to 0.3 mass% or less. The drying air contains plasticizers, UV absorbers and other high-boiling substances in addition to the solvent gas, so these were removed by a cooler and pre-adsorber to be removed by cooling and used for recycling. 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 a condensation method among all the evaporation solvents was 90 mass%, and most of the remainder was collect | recovered by adsorption collection.

  The dried film 82 was conveyed to a first humidity control chamber (not shown). A drying air of 110 ° C. was sent out to the transition part between the drying chamber 51 and the first humidity control chamber. Air having a temperature of 50 ° C. and a dew point of 20 ° C. was sent to the first humidity control chamber. Further, the film 82 was transported to a second humidity control chamber (not shown) that suppresses the curling of the film 82. In the second humidity control chamber, air of 90 ° C. and humidity 70% was sent directly to the film 82.

  The film 82 after humidity control was cooled to 30 ° C. or lower in the cooling chamber 52 and then subjected to ear cutting again at both ends with an ear cutting device (not shown). In addition, a forced static elimination device (static elimination bar) 93 was installed so that the charged voltage of the film 82 being conveyed was always in the range of −3 to +3 kV. Further, knurling was applied to both ends of the film 82 by a knurling roller 94. The knurling was imparted by embossing from one side of the film 82. At this time, the width for applying the knurling was 10 mm, and the pressing pressure by the knurling application roller was set so that the height of the unevenness was 12 μm higher than the average thickness of the film 81.

  Finally, the film 82 was conveyed to the winding chamber 53. The winding chamber 53 was kept at a room temperature of 28 ° C. and a humidity of 70%. An ion wind neutralization device (not shown) was installed inside the winding chamber 53 so that the charged voltage of the film 82 was -1.5 to +1.5 kV. The film (thickness 80 μm) 82 thus obtained had a width of 1475 mm and a total winding length of 3940 m. The diameter of the winding roller 95 was 169 mm. The tension at the start of winding was 300 N / m, and the tension at the end of winding was 200 N / m. In addition, the fluctuation width (sometimes referred to as the oscillating width) of the winding deviation at the time of winding was set to ± 5 mm, and the winding deviation period with respect to the winding roller 95 was set to 400 m. The pressing pressure of the press roller 96 against the winding roller 95 was set to 50 N / m. The temperature of the film 82 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.

  A film 82 was produced using the same dope 27 and production method as in Example 1. However, an L-shape in which an L-shaped windbreak plate 101 was attached to both side members 71b was used as the air duct 70 (see FIG. 5). In addition, the kind, arrangement | positioning conditions, and C1 of the rectifying fin 100 were made into the same conditions as Example 1. FIG.

  A film 82 was produced using the same dope 27 and production method as in Example 1. However, as the air duct 70, a lower installation type in which a single windproof plate 122a is attached to both side members 71b and a plurality of rectifying fins 100 are attached to the lower member 71c as windproof plates 122b (see FIG. 6). . In addition, the kind, arrangement | positioning conditions, and C1 of the rectifying fin 100 were made into the same conditions as Example 1. FIG.

  A film 82 was produced using the same dope 27 and production method as in Example 1. However, as the air duct 70, the windproof plate 101 was not attached, and the air duct 71a only with the rectifying fins 100 installed therein was used. The type and arrangement conditions of the rectifying fins 100 were the same as those in the first embodiment.

  A film 82 was produced using the same dope 27 and production method as in Example 1. As the air duct 70, the same single sheet type as in Example 1 was used, but C1 was set to 35 mm.

[Comparative Example 1]
A film was produced using the same dope 27 and production method as in Example 1. However, as the air duct, one in which the rectifying fin 100 and the windbreak plate 101 were not installed was used.

[Film evaluation]
The unevenness on the surface of each produced film was evaluated. Evaluation was made using an electronic micrometer (manufactured by Anritsu Electric Co., Ltd.), and the thickness was measured at any 10 locations on the film, and the relative standard deviation RSD (unit:%) was calculated from the average value and deviation of the measured values. The calculation was performed. RSD is a value obtained by {(deviation) / (average value)} × 100. And the number of the uneven | corrugated unevenness | corrugation evaluation result in Table 1 represents the following results.
1: When the RSD value is less than 5% and the flatness is extremely excellent 2: When the RSD value is 5% or more and less than 10% and the flatness is excellent 3: The RSD value is 10% or more and 15% Although unevenness unevenness is slightly recognized
When there is no problem as a product 4: The RSD value is 15% or more and less than 20%, and unevenness is confirmed.
When there is no problem 5: The RSD value is 20% or more, and clear unevenness frequently occurs.
Cannot be used as

  Table 1 shows the evaluation results and production conditions of the films produced in Examples 1 to 5 and Comparative Example 1.

The composition of the dope 27 of Example 1 was changed to the following.
[composition]
Cellulose triacetate (TAC) 100 parts by mass (acetyl group substitution degree 2.81 (acetylation degree 60.2%), Mw / Mn = 2.7, viscosity average polymerization degree 305, viscosity of 6% by mass in dichloromethane solution 350 mPa · s)
-Dichloromethane (first solvent) 430 parts by mass-Methanol (second solvent) 48 parts by mass-Plasticizer A 7.6 parts by mass-Plasticizer B 3.8 parts by mass The above-mentioned plasticizer A is triphenyl phosphate ( TPP), plasticizer B is biphenyl diphenyl phosphate (BDP).

  An additive liquid A was prepared with the retardation control agent shown in Chemical formula 1, a part of the dope 27 and a solvent of dichloromethane: methanol = 9: 1 (mass ratio) and filtered.

  Further, the additive liquid B was prepared by mixing fine particles (trade name; Aerosil R972, Nippon Aerosil Co., Ltd.), a part of the dope 27 and a solvent of dichloromethane: methanol = 9: 1 (mass ratio). . In the additive liquid B, the following fine particles were dispersed by an attritor so that the volume average particle diameter was 0.7 μm. The additive liquid B after dispersion was filtered.

  The additive liquid B was mixed with the additive liquid A using an in-line mixer, and this mixed liquid was mixed with the dope 27 using an in-line mixer. In this way, a liquid having a matting agent content of 1% by mass and a retardation control agent of 6% by mass was obtained for casting when the film 82 was formed. Other conditions are the same as those in the first embodiment.

  The dope 27 subjected to casting was the same as in Example 6, and the other conditions were the same as in Example 2.

  The dope 27 subjected to casting was the same as in Example 6, and the other conditions were the same as in Example 3.

  The dope 27 subjected to casting was the same as in Example 6, and the other conditions were the same as in Example 4.

  The dope 27 subjected to casting was the same as in Example 6, and the other conditions were the same as in Example 5.

[Comparative Example 2]
The dope 27 subjected to casting was the same as in Example 6, and the other conditions were the same as in Comparative Example 1.

  The same evaluation as in Examples 1 to 5 and Comparative Example 1 was performed on the films obtained in Examples 6 to 10 and Comparative Example 2. The evaluation results and manufacturing conditions are shown in Table 2.

  According to the above embodiment, when the present invention is used, it is possible to manufacture the film 82 having excellent flatness by suppressing the generation of unevenness on the surface of the casting film 69 due to the flow of the drying air and the accompanying air. confirmed.

The schematic of the dope production line in this invention is shown. The schematic of the film production line in this invention is shown. The arrangement | positioning figure of the ventilation duct in the casting chamber in this invention is shown. The schematic of the ventilation duct (one piece type) in this invention is shown. The schematic of an example (L-shaped) of the ventilation duct in this invention is shown. The schematic of an example (rectifier fin type) of the ventilation duct in this invention is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Dope production line 27 Dope 40 Film production line 46 Casting band 64 Casting chamber 69 Casting film 70 Blowing duct 82 Film 100 Rectification fin 101 Windshield

Claims (12)

Casting comprising casting film forming means for casting a dope from a casting die on a traveling support to form a casting film, and air blowing means for sending air to the entire width region of the casting film immediately after being formed. In the device
The air blowing means is provided so that the air blowing port faces in the direction in which the support travels,
The air outlet is provided with a first rectifying member that divides into a plurality in the width direction of the support so that the wind to be emitted is blown substantially in parallel with the support and in the traveling direction of the support. A casting apparatus characterized by.   The casting apparatus according to claim 1, wherein a plurality of the first rectifying members are provided in the blower opening at an installation interval of 30 to 80 mm or less.   The air blowing means has a substantially box-shaped air blowing portion having the air blowing port on one side, and wind-proof members for suppressing accompanying air generated along with the air blowing are provided on both side surfaces of the air blowing portion. The casting apparatus according to claim 1 or 2, wherein   4. The casting apparatus according to claim 3, wherein the wind-proof member is a wind-proof plate that is provided perpendicularly to the support and extends toward the support.   The casting apparatus according to claim 4, wherein a distance C1 between the lower end of the windbreak plate and the casting film is 1 mm or more and 30 mm or less.   The distance C2 between the lower surface of the blower section and the casting film is 1 mm or more and 300 mm or less, and is larger than the distance C1 between the windproof member and the casting film. Casting equipment.   A rectifying plate as a second rectifying member is provided on the lower surface of the air blowing portion so that the air emitted from the air blowing port is substantially parallel to the support body and blows in the direction of travel of the support body. The casting apparatus according to any one of claims 1 to 6, wherein the casting apparatus is provided along a traveling direction.   The casting apparatus according to claim 7, wherein a plurality of the current plates are provided at an installation interval of 50 to 400 mm in the width direction of the support.   A solution casting apparatus comprising: the casting apparatus according to any one of claims 1 to 8; and a drying unit that dries the casting film peeled off as a film from the support. A casting process in which a dope is cast on a traveling support to form a cast film, and the cast film is blown to the cast film immediately after the formation by a blowing means, and the cast film is peeled off as a film from the support. In a solution casting method having a drying step of drying
By directing the air blowing port of the air blowing means having the air blowing port over the entire width of the casting membrane in the direction of travel of the support and dividing the air blowing port in advance in the width direction of the casting membrane, the air blowing port. The solution casting method according to claim 1, wherein a wind coming out of the support blows in a direction substantially parallel to the support and in a traveling direction of the support. A plurality of first rectifying members for partitioning the air blowing port in the width direction are provided in the air blowing port,
The solution casting method according to claim 10, wherein an installation interval of the first rectifying members is set according to disturbance in a direction of air blowing from the air blowing port. The blower unit has a blower part having the blower opening on one surface facing the traveling direction of the support, and windproofing is provided on both sides of the blower part to suppress the accompanying wind generated by the blown air. Members are provided,
The solution casting method according to claim 10 or 11, wherein a distance C1 between the windproof member and the casting film is set according to the wind force of the accompanying wind.

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