JP2007137962A - Preparation method of dope - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dope of an approximately constant temperature and of an even quality. <P>SOLUTION: A cylinder 24 is cooled by pouring a refrigerant 35 in a jacket 23 within an extruder 20. A swollen liquid 16 containing TAC and a mixed solvent stored in a tank 21 is suitably charged in the cooled cylinder 24. The swollen liquid 16 is agitated by rotating a screw 22. A dope (a first dope 17) is produced by dissolving TAC in the mixed solvent. A rotation frequency of the screw 22 is detected by a second controller 27, and a refrigerant circulator 25 is controlled in response to the frequency to adjust a flow rate of the refrigerant 35. A temperature of the discharged dope is measured by the use of a thermometer 36 set in an immediate vicinity of an extruder outlet 20a, and in response to the temperature, the refrigerant circulator 25 is controlled by a first controller 26. In such a manner described above, the dope of an approximately constant temperature and of an even quality can be obtained. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for preparing a dope.

  High molecular compounds (hereinafter referred to as polymers) are used in various fields because of their ease of handling and the ability to freely create shapes, and their manufacturing methods also depend on the product application. It exists in a wide variety. For example, a plastic film is prepared by a melt film-forming method in which a polymer is heated to a molten state or a liquid (hereinafter referred to as a dope) in which a solute such as a polymer is dissolved or dispersed in an organic solvent. It is manufactured by the solution casting method etc. which form into a film using. In this solution casting method, a film is produced by casting a dope on a support and then volatilizing a solvent in the dope.

  At this time, as the solvent used for the dope, the most appropriate one is selected in consideration of the solubility and volatility of the polymer, the influence on the human body and the environment, and the like. For example, when producing a cellulose triacetate (hereinafter also referred to as TAC in combination with cellulose triacetate (triacetylcellulose)) film which is often used as a photographic film base, methylene chloride (methylene chloride, dichloromethane) is used as a main solvent, Manufactured by a solution casting method. Since the TAC film produced in this way is excellent in optical isotropy, it is also used as an optical functional film such as a polarizing plate protective film (for example, see Non-Patent Document 1).

  However, methylene chloride, which is used as the main solvent, is a substance that may be adversely affected by humans and the environment, so it is necessary to switch to an alternative product. As an alternative to this methylene chloride, for example, methyl acetate, acetone, etc. that have little influence on the human body and the environment can be mentioned. However, these solvents have a problem that TAC is difficult to dissolve.

Then, when preparing dope, the cooling melt | dissolution apparatus using a screw mixer (screw extruder) is proposed as an apparatus which improves the solubility of TAC with respect to a solvent (for example, refer nonpatent literature 2). According to this method, TAC and acetone having a substitution degree of 2.80 (acetylation degree of 60.1%) to a substitution degree of 2.90 (acetylation degree of 61.3%) are -80 ° C or higher and -70 ° C or lower. After cooling, the mixture is heated to obtain a dope in which TAC is dissolved in 0.5 wt% or more and 5 wt% or less in acetone. Such a method of preparing a dope by cooling a solvent containing a polymer is referred to as a cooling dissolution method. Although the cooling dissolution method is applied to the spinning method technology, the cooling dissolution method has been studied in consideration of the mechanical properties and dyeability of the obtained fiber and the cross-sectional shape of the fiber, and is 10% by weight or more. It has also been reported that a dope having a concentration of 25% by weight or less can be obtained (for example, see Non-Patent Document 3).
Japan Society for Invention and Innovation Public Technical Bulletin No. 2001-1745 J. et al. M.M. G. Cowie et al., “Makromol, Chem” 1971, 143, 105. Kenji Kamide et al. “Dry-spinning of cellulose triacetate from acetone solution” Journal of Textile Machinery Society, (1981), 34, 57-61

  By the way, this cooling dissolution method is to secure the solubility of TAC in the solvent by holding the temperature for a predetermined time after cooling the raw material containing TAC and the solvent to a predetermined temperature. When applied to the dope manufacturing process, as used in Non-Patent Document 2, it is effective to use a cooling-type screw extruder capable of feeding a viscous liquid and having a high heat exchange rate. is there. However, when such a screw extruder (hereinafter referred to as an extruder) is used, it is important to uniformly control the solubility of the dope and the flow rate of liquid fed to the next process.

  However, if the physical properties of the dope raw material (or dope) inside the extruder are different, the temperature of the dope discharged from the extruder may not be constant due to the rotation of the screw of the extruder. If the temperature of the dope supplied to the next process is different in this way, for example, the manufacturing conditions in the following process such as the cooling process, the heating process, and the filtration process will be different. The conditions must be sought, resulting in a deterioration in productivity such as an increase in working hours.

  Therefore, the present invention proposes a dope preparation method capable of supplying a dope having a constant temperature to the next step while improving the solubility of the polymer in the solvent during dope preparation using an extruder. .

  The dope preparation method of the present invention is a dope preparation method for preparing a dope containing a polymer and a solvent, using an extruder having a screw having a rotation function and a jacket in which a channel is formed. A cooling and dissolving step of dissolving the polymer in the solvent by rotating the screw after supplying the polymer and the solvent into the extruder cooled by flowing the cooling medium into the screw, and the number of rotations of the screw The temperature of the dope discharged from the extruder is made substantially constant by adjusting the flow rate of the cooling medium according to the above.

  The temperature of the cooling medium is preferably set to −120 ° C. or higher and 0 ° C. or lower. Further, it is preferable to use at least one of methanol, dichloromethane, fluorocarbon, and hydrofluoroether as the cooling medium.

  It is preferable that the average temperature T (° C.) of the dope when discharged from the extruder is substantially constant in the range of −100 ° C. to 0 ° C. And in the extruder, it is preferable that the temperature range of dope is (T-5) degreeC or more and (T + 5) degreeC or less with respect to dope average temperature T (degreeC). In addition, it is preferable that a polymer is a cellulose acylate.

  According to the present invention, at the time of dope preparation, using an extruder that can be cooled by flowing a cooling medium through a channel formed in the jacket, the polymer and the solvent are cooled, and the screw is rotated and stirred. By doing so, the polymer can be dissolved in the solvent while exhibiting excellent solubility. Further, since the flow rate of the cooling medium is adjusted according to the number of rotations of the screw, a constant dope temperature can always be maintained. Thereby, since the temperature of the dope at the time of supplying to the next process is always constant, the film can be manufactured while maintaining excellent productivity under certain conditions regardless of the lot even after the next process.

  Hereinafter, embodiments of the present invention will be described in detail. 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 substitution degree of the acyl group to the hydroxyl group of cellulose satisfies all of the following formulas (I) to (III) are more preferable. In the following formulas (I) to (III), A and B represent the substitution degree of the acyl group with respect to the hydrogen atom in the hydroxyl group of cellulose, A is the substitution degree of the acetyl group, and B is 3 carbon atoms. The substitution degree of the acyl group of ˜22. In addition, it is preferable that 90 mass% or more of TAC is a particle | grain of 0.1-4 mm. However, the polymer that can be used in the present invention is not limited to cellulose acylate.
(I) 2.5 ≦ A + B ≦ 3.0
(II) 0 ≦ A ≦ 3.0
(III) 0 ≦ B ≦ 2.9

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

  The total degree of acylation substitution, 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. Here, DS2 is the ratio of the hydrogen of the hydroxyl group at the 2-position in the glucose unit (hereinafter referred to as the acyl substitution degree at the 2-position), and DS3 is the hydroxyl group at the 3-position in the glucose unit. This is the rate at which hydrogen is substituted by an acyl group (hereinafter referred to as the 3-position acyl substitution degree), and DS6 is the rate at which the hydrogen at the 6-position hydroxyl group is substituted by an acyl group in a glucose unit (hereinafter, (Referred to as the degree of acyl substitution at the 6-position).

  Only one type of acyl group may be used in the cellulose acylate of the present invention, or two or more types of acyl groups may be used. When two or more kinds of acyl groups are used, it is preferable that one of them is an acetyl group. 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 sum of the degree of substitution of the hydroxyl groups at the 2nd, 3rd and 6th positions by acyl groups other than acetyl groups When DSB is DSB, the value of DSA + DSB is preferably 2.22 to 2.90, and 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 value of DSA + DSB at the 6-position of cellulose acylate is 0.75 or more, more preferably 0.80 or more, and particularly preferably cellulose acylate of 0.85 or more. These cellulose acylates By using, a solution (dope) having better solubility can be produced. In particular, when a non-chlorine organic solvent is used, a dope having excellent solubility, low viscosity and excellent filterability can be produced.

  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 the cellulose acylate in the present invention 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, halogenated hydrocarbons having 1 to 7 carbon atoms are preferably used, and dichloromethane is most preferably used. From the viewpoint of physical properties such as solubility of TAC, peelability from cast film support, mechanical strength and optical properties of film, one or several kinds of alcohols with 1 to 5 carbon atoms are mixed in addition to dichloromethane. It is preferable to do. As for content 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, and n-butanol, but methanol, ethanol, n-butanol, or a mixture thereof is preferably used.

  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. Sometimes used. 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 the solvent.

  The details of cellulose acylate are described in paragraphs [0140] to [0195] of JP-A-2005-104148, and these descriptions can also be applied to the present invention. 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, and release accelerators. The details are described in paragraphs [0196] to [0516] of JP-A-2005-104148, and these descriptions can also be applied to the present invention.

[Dope Preparation Method]
(Swelling process)
In the swelling step, cellulose acylate as a raw material for the dope is mixed with a solvent such as a mixed solvent to swell the cellulose acylate in the solvent. The temperature of the solvent in the swelling step is preferably −10 ° C. or higher and 55 ° C. or lower, and is usually performed at room temperature. The ratio between the cellulose acylate and the solvent is determined according to the concentration of the dope finally obtained. In general, the amount of cellulose acylate in the swelling step is preferably 5% by weight or more and 30% by weight or less, more preferably 8% by weight or more and 20% by weight or less with respect to the dope to be prepared. Most preferably, it is at least 15% by weight. The swollen mixture of the solvent and cellulose acylate is preferably stirred until the cellulose acylate is sufficiently swollen. The stirring time is preferably 10 minutes or more and 150 minutes or less, and more preferably 20 minutes or more and 120 minutes or less because the cellulose acylate can be sufficiently swollen. In the swelling process, in addition to the solvent and cellulose acylate, additives such as a plasticizer, an anti-degradation agent, and an ultraviolet absorber are added for the purpose of imparting desired characteristics and expressing functions. May be.

(Dope production)
FIG. 1 is a process diagram showing a flow when preparing a dope in the present invention. The dope manufacturing process 10 includes a cooling dissolution process 11, a cooling process 12, a heating process 13, and a filtration process 14. And the dope 15 manufactured in this dope manufacturing process 10 is used for the film manufacturing process 50, and a film is manufactured.

  In the cooling and dissolving step 11, the swelling liquid 16 prepared as described above is stirred while being cooled by a single screw extruder (hereinafter referred to as an extruder) to prepare the first dope. Next, the first dope is supplied to the cooling step 12 and then continuously supplied to the heating step 13 to prepare the second dope. The second dope is filtered in the filtering step 14 to produce the dope 15. In this embodiment, the dope obtained after the cooling and dissolving step 11 is the first dope 17, the dope obtained after the heating step 13 is obtained after the second dope 18, and the second dope 18 is filtered. The dope 15 is referred to as the dope 15, but the cooling step 12, the heating step 13, and the filtration step 14 are omitted, and the dope 15 in which the polymer is sufficiently dissolved in the cooling and dissolving step 11 is used for manufacturing the film. You can also.

  FIG. 2 is a schematic view of the extruder 20 used in the dope manufacturing process 10. The extruder 20 includes a tank 21 and a screw 22 therein, and further includes a cylinder 24 including a jacket 23, a refrigerant circulator 25, a first controller 26, and a second controller 27. ing.

  A certain amount of swelling liquid 16 is stored inside the tank 21. Then, the swelling liquid 16 is appropriately charged from the tank 21 into the cylinder 24. The method of charging the swelling liquid 16 may be a batch type or a continuous type, but in this embodiment, a batch type is applied. Inside the cylinder 24, the swelling liquid 16 is agitated by rotating the screw 22 having the screw blade 22b attached to the screw shaft 22a. A jacket 23 divided into a plurality of parts is attached to the outer peripheral portion of the cylinder 24. It is preferable to use the jacket 23 partitioned in this manner because the swelling liquid 16 and the first dope 17 can be efficiently fed and temperature control such as cooling can be efficiently performed. In this embodiment, the jacket 23 is divided into two, and the inlet side is referred to as an inlet side jacket 23a and the outlet side is referred to as an outlet side jacket 23b.

  Before supplying the swelling liquid 16 to the inside of the cylinder 24, a cooling medium (refrigerant) 35 adjusted to a desired temperature in advance is sent to the inside of the jacket 23. At this time, the temperature of the first dope 17 at the extruder outlet 20a can be controlled by supplying the inlet-side refrigerant 35a into the inlet-side jacket 23a and the outlet-side refrigerant 35b into the outlet-side jacket 23b, respectively. it can. In the present invention, the refrigerant 35 is not particularly limited, but methanol, dichloromethane, fluorocarbon, hydrofluoroether or the like is preferably used. The temperature of the refrigerant 35 is preferably in the range of −120 ° C. or more and 0 ° C. or less, more preferably −100 ° C. or more and −40 ° C. or less, and most preferably −90 ° C. or more and −50 ° C. or less. However, it is not particularly limited.

  A thermometer 36 is attached in the vicinity of the extruder outlet 20a. With this thermometer 36, the temperature of the first dope 17 discharged from the extruder outlet 20a is measured. After the measurement, this temperature measurement value is transmitted to the first controller 26. Then, according to the received temperature measurement value, the refrigerant circulator 25 is controlled by the first controller 26 so that the temperature of the first dope 17 near the extruder outlet 20a is always constant. A second controller 27 that measures the number of rotations of the screw 22 is attached to the inside of the extruder 20. The rotation speed of the screw 22 is always transmitted to the second controller 27. A signal related to the rotational speed is transmitted from the second controller 27 to the refrigerant circulator 25. Then, the movement of the refrigerant circulator 25 is controlled in accordance with the change in the rotational speed of the screw 22, and the temperature of the first dope 17 near the extruder outlet 20a is adjusted to be substantially constant as described above. Has been. The refrigerant circulator 25 is provided with pumps 40 and 41 capable of adjusting the flow rate of the refrigerant, and a desired amount of the refrigerant 35 is sent to the jackets 23a and 23b by the pumps 40 and 41.

  As described above, according to the rotation speed of the screw 22, that is, the rotation speed of the screw 22 is changed from a high speed rotation to a low speed rotation, or according to a change in the rotation speed from the low speed rotation to the high speed rotation, the flow rate of the refrigerant 35. By changing the flow rate from a high flow rate to a low flow rate or from a low flow rate to a high flow rate, the average temperature T (° C.) of the first dope 17 at the extruder outlet 20a can be kept substantially constant. As described above, when the temperature (discharge temperature) of the first dope 17 when discharged from the extruder 20 is substantially constant, the TAC and the solvent are uniformly distributed in the cooling process 12 and the heating process 13 which are the next processes. Since the mixed dope can be prepared and the inclusion and aggregation of foreign substances can be suppressed, the load on the filter in the filtration step 14 can be suppressed, and a high-quality dope 15 can be produced. can do. In addition, regarding the rotation speed of the screw 22, high-speed rotation is a case where the rotation speed is 5 rpm or more and 200 rpm or less, and a high-speed flow rate is a case where liquid is fed at a high speed of 30 L / min or more and 200 L / min or less.

  Hereinafter, the dope preparation method by the extruder 20 is demonstrated. A desired amount (for example, 1.0 L / min or more and 5.0 L / min or less) of the swelling liquid 16 is charged from the tank 21 into the cylinder 24 in a batch manner. At this time, it is preferable to rotate the screw 22 at a high speed. In this case, the flow rate of the refrigerant 35 is preferably a high-speed flow rate for both the jackets 23a and 23b. Thereby, the production | generation of the 1st dope 17 which suppressed generation | occurrence | production of a foreign material etc., hold | maintaining sufficient manufacturing speed, and was maintained at temperature substantially constant with high purity can be manufactured by high productivity.

  As described above, the average temperature T (° C.) of the first dope 17 at the extruder outlet 20a is optimized by optimizing the manufacturing conditions such as the rotational speed and flow rate of the screw 22 by controlling the refrigerant circulator 25. Is substantially constant in a range from −100 ° C. to 0 ° C. In the extruder 20, the temperature range of the first dope 17 is set to (T−5) ° C. or more and (T + 5) ° C. or less with respect to the average temperature T. More preferably, the temperature range of the first dope 17 is (T−3) ° C. or more and (T + 3) ° C. or less with respect to the average temperature T.

  The first dope 17 discharged from the extruder outlet 20a is sent to the inside of a cooler (not shown) in which the cooling step 12 is performed. And the cooling melt | dissolution of the 1st dope 17 is further accelerated | stimulated within a cooler. The temperature t1 (° C.) and the residence time (minutes) inside the cooler are not particularly limited, but t1 is preferably −100 ° C. or higher and 0 ° C. or lower, more preferably −90 ° C. or higher. It is −30 ° C. or lower, and most preferably −80 ° C. or higher and −50 ° C. or lower. The residence time is preferably 0 minutes or more and 60 minutes or less, more preferably 5 minutes or more and 30 minutes or less, and most preferably 8 minutes or more and 15 minutes or less. Thereby, a solute such as a polymer is more easily dissolved in the solvent, and the uniform first dope 17 is obtained.

  After the cooling step 12, the first dope 17 is sent to the heating step 13. In the heating step 13, the first dope 17 sent to the inside of a heater (not shown) is heated. Thereby, the 2nd dope 18 by which the component which is not melt | dissolved by cooling melt | dissolution was melt | dissolved is obtained. At this time, the heating temperature t2 (° C.) and the residence time (minute) of the heater are not particularly limited, but t2 is preferably 0 ° C. or more and 100 ° C. or less, more preferably t2 is 10 It is 20 degreeC or more and 60 degrees C or less, Most preferably, t2 is 20 degreeC or more and 40 degrees C or less. The residence time is preferably 0 minutes or more and 30 minutes or less, more preferably 3 minutes or more and 20 minutes or less, and most preferably 5 minutes or more and 10 minutes or less. Although the form of the heater is not particularly limited, it is preferably a jacketed pipe capable of controlling the temperature. Further, in order to promote the dissolution of the polymer in the solvent, the first dope 17 and the first dope The structure which can pressurize 2 dope 18 is more preferable.

  The second dope 18 is brought to substantially room temperature by a temperature controller (not shown) and then sent to the filtration step 14. In the filtration step 14, the second dope 18 is filtered by a filter (not shown), and foreign matters are removed to obtain the dope 15. The filter used in the filter is not particularly limited, but the average pore diameter is preferably 100 μm or less. Moreover, it is preferable that the filtration flow rate is substantially constant. After the filtration, the dope 15 is sent to the film production line 50 to produce the film.

  By the way, once the swelling liquid 16 is prepared as described above, the method of using the swelling liquid 16 as the dope 15 increases the time required for increasing the concentration of cellulose acylate, which is problematic in terms of manufacturing cost. There is a case. Therefore, in order to improve this problem, it is preferable to prepare the dope 15 having a concentration lower than the target concentration and then perform the concentration step to obtain the target dope concentration. In this case, the dope 15 after the filtration step 14 may be sent to a flash device (not shown) and concentrated by evaporating a part of the solvent in the dope 15 in the flash device. In addition, after the solvent gas generated by evaporation is condensed and liquefied by a condenser (not shown), it is recovered by a recovery device, and this recovered solvent is reused as a solvent for dope preparation by a regenerator. This is preferable because an effect can be obtained. Then, the concentrated dope 15 is extracted from the flash device by a pump. At this time, it is preferable that a bubble removal process is performed to remove bubbles generated in the dope 15. As this defoaming method, various known methods are applied, for example, an ultrasonic irradiation method. Thereafter, the dope 15 is sent to a filter to remove foreign substances, thereby becoming the dope 15 used for film production. However, the temperature of the dope 15 during filtration is preferably 0 ° C. or higher and 200 ° C. or lower.

  By the above method, the dope 15 having a cellulose acylate concentration of 5% by mass or more and 40% by mass or less can be manufactured. At this time, the cellulose acylate concentration is more preferably 15% by mass or more and 30% by mass or less, and most preferably 17% by mass or more and 25% by mass or less. Further, the concentration of the additive such as a plasticizer is preferably in the range of 1% by mass or more and 20% by mass or less when the total solid content in the dope 15 is 100% by mass. In addition, about the manufacturing method of dopes, such as the raw material in the solution film forming method used for manufacture of a cellulose acylate film, a raw material, an additive, the addition method, a filtration method, and defoaming, Unexamined-Japanese-Patent No. 2005-104148 [0517] paragraph to [0616] paragraph of the publication number, and these descriptions can also be applied to the present invention.

[Solution casting method]
Next, a method for producing a film using the dope 15 prepared by the above method will be described. In this embodiment, the manufacturing method of a cellulose acylate film is shown as the example. FIG. 3 is a schematic view showing the film manufacturing facility 50. However, the present invention is not limited to the form shown in FIG.

  The film production facility 50 includes a stock tank 51, a pump 52, a filtration device 53, a casting die 54, and a casting band 57 that is stretched around rotating rollers 55 and 56. Further, on the downstream side, a tenter dryer 58, an edge-cutting device 60, a drying chamber 61, a cooling chamber 62, a winding chamber 63 and the like are arranged.

  An agitator 71 that is rotated by a motor 70 is attached to the stock tank 51. The stock tank 51 is connected to a casting die 54 via a pump 52 and a filtration device 53.

As a material of the casting die 54, precipitation hardening type stainless steel is preferable, and its thermal expansion coefficient is preferably 2 × 10 ⁻⁵ (° C. ⁻¹ ) or less. Pitting (perforation) does not occur at the gas-liquid interface even when immersed in a mixed solution of dichloromethane, methanol, or water for 3 months in a forced corrosion test with an aqueous electrolyte solution that has approximately the same corrosion resistance as SUS316. Those having corrosion resistance can also be used as the material of the casting die 54. In addition, it is preferable that the casting die 54 is manufactured by grinding a material that has passed one month or more after casting. Thereby, it is possible to prevent the dope 15 from flowing uniformly in the casting die 54 and causing streaks or the like in the casting film 80 to be described later.

  The finishing accuracy of the wetted surface of the casting die 54 is preferably 1 μm or less in terms of surface roughness and the straightness is 1 μm / m or less in any direction. The clearance of the slit of the casting die 54 can be adjusted in the range of 0.5 mm to 3.5 mm by automatic adjustment. About the corner | angular part of the liquid-contacting part of the lip tip of the casting die 54, R is 50 micrometers or less over the whole width. Further, it is preferable that the shear rate in the casting die 54 is adjusted to be 1 (1 / second) or more and 5000 (1 / second) or less.

  The width of the casting die 54 is not particularly limited, but is preferably 1.1 times or more and 2.0 times or less the width of the film to be the final product. Further, it is preferable to attach a temperature controller (not shown) to the casting die 54 so that the temperature during film formation is maintained at a predetermined temperature, and the casting die 54 is of a coat hanger type. Is preferred. Furthermore, it is more preferable that thickness adjusting bolts (heat bolts) are provided at predetermined intervals in the width direction of the casting die 54 and the casting die 54 is provided with an automatic thickness adjusting mechanism using a heat bolt. The heat bolt is preferably formed by setting a profile in accordance with a liquid feeding amount of the pump 52 by a preset program. The pump 52 is preferably a high precision gear pump.

  At this time, 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, should be adjusted within 1 μm, and the difference between the minimum value and the maximum value in the width direction thickness should be adjusted to 3 μm or less. Is preferable, and 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 54. The method for forming the cured film is not particularly limited, and examples thereof include ceramic coating, hard chrome plating, and a nitriding method. When ceramic is used as the cured film, it can be ground, has a low porosity, is not brittle and has excellent corrosion resistance, and has good adhesion to the casting die 54, while it adheres to the dope 15. Is preferable. Specific examples include tungsten carbide (WC), Al ₂ O ₃ , TiN, and Cr ₂ O ₃ , among which WC is preferable. In addition, this WC coating can be performed by a thermal spraying method.

  A solvent supply device (not shown) is preferably attached to the slit end of the casting die 54 in order to prevent the outflow dope 15 from locally drying and solidifying. Further, a solvent for solubilizing the dope 15 (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) It is preferable to supply near the periphery of the three-phase contact line formed by outside air. At this time, it is preferable to supply the solvent to one side of the end portion at a rate of 0.1 mL / min to 1.0 mL / min, since foreign matters can be prevented from entering the casting film 80. 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 57 is provided below the casting die 54 so as to span the rotating rollers 55 and 56. The rotating rollers 55 and 56 are rotated by a driving device (not shown), and the casting band 57 travels endlessly with the rotation. It is preferable that the casting band 57 can move at a moving speed, that is, a casting speed of 10 m / min or more and 200 m / min or less. Further, in order to set the surface temperature of the casting band 57 to a predetermined value, it is preferable that the heat transfer medium circulation device 73 is attached to the rotary rollers 55 and 56, and the surface temperature of the casting band 57 is − It is preferable that the temperature can be adjusted to 20 ° C or higher and 40 ° C or lower. A heat transfer medium flow path (not shown) is formed in each of the rotating rollers 55 and 56 used in the present embodiment, and passes through the heat transfer medium held at a predetermined temperature therein. By doing so, the temperature of the rotating rollers 55 and 56 is maintained at a predetermined value.

  The width of the casting band 57 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 15, and the length is 20 m or more. It is preferable that the surface is 200 m or less, the thickness is 0.5 mm or more and 2.5 mm or less, and the surface roughness is 0.05 μm or less. The casting band 57 is preferably made of stainless steel, and more preferably made of SUS316 so as to have sufficient corrosion resistance and strength. Further, it is preferable to use a non-uniform thickness of the casting band 57 of 0.5% or less.

The rotating rollers 55 and 56 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 55 and 56 is preferably 0.01 μm or less. Therefore, the surface of the rotary rollers 55 and 56 is subjected to chrome plating or the like so as to have sufficient hardness and durability. In addition, it is necessary to suppress the surface defects of the support (the casting band 57 and the rotating rollers 55 and 56) to the minimum. Specifically, there are no pin hole of at least 30 [mu] m, pinholes or more and less than 10 [mu] m 30 [mu] m is not less 1 / m ² or less, it is preferable pinholes less than 10 [mu] m is 2 or / m ² or less.

  The casting die 54 and the casting band 57 are accommodated in a casting chamber 74. The casting chamber 74 is provided with a temperature control equipment 75 for keeping the internal temperature at a predetermined value, and a condenser (condenser) 76 for condensing and recovering the volatile organic solvent. In addition, a recovery device 77 for recovering the condensed organic solvent is provided outside the casting chamber 74. Note that a decompression chamber 78 for controlling the pressure of the back surface of the casting bead formed from the casting die 54 to the casting band 57 is preferably disposed behind the casting die 54. This is also used in the form. It is preferable that a jacket (not shown) is attached to the decompression chamber 78 and the temperature is controlled so that the internal temperature is kept at a predetermined temperature. The temperature of the decompression chamber 78 is not particularly limited, but is preferably adjusted so as to be equal to or higher than the condensation point of the solvent used. In addition, if a suction device (not shown) is attached to the edge portion of the casting die 54 and the edge suction air volume is in the range of 1 L / min to 100 L / min by this suction device, the shape of the casting bead is desired. It is preferable because it can be maintained.

  Near the peripheral surface of the casting band 57, air blowing ports 81, 82, 83 used for evaporating the solvent in the casting film 80 are provided. Further, in order to prevent the surface shape of the casting film 80 from being fluctuated by the drying air being blown onto the casting film 80 immediately after casting, a windshield plate is provided in the air blowing port 81 in the vicinity of the casting die 54. 84 is preferably provided. In addition, the installation location of each ventilation port 81-83 is not limited to this form, If it adjusts so that a solvent can be volatilized effectively by ventilating with respect to the casting film 80 Good. Moreover, although the form which provided the ventilation port was shown in this embodiment as a means to volatilize a solvent, the heating apparatus etc. which can heat the casting film 80 directly or indirectly can also be used.

  The crossing unit 90 includes a plurality of rollers 90 a and a blower 91. A tenter dryer 58 and an ear clip device 60 are disposed downstream of the crossover section 90. A crusher 92 for finely cutting the side end (ear) of the cut film 100 is connected to the ear clip device 60.

  A large number of rollers 93 and an adsorption / recovery device 94 for adsorbing and recovering the solvent gas generated by evaporation are attached to the drying chamber 61. In FIG. 3, the cooling chamber 62 is provided downstream of the drying chamber 61, but a humidity control chamber (not shown) is provided between the drying chamber 61 and the cooling chamber 62 to control the humidity of the film 100. May be.

  A forced static elimination device (static elimination bar) 95 for adjusting the charged voltage of the film 100 to be within a predetermined range (for example, −3 kV to +3 kV) is provided downstream of the cooling chamber 62. In addition, in FIG. 3, although the form which makes the forced static elimination apparatus 95 the downstream of the cooling chamber 62 is shown, it is not limited to this form. In this embodiment, a knurling roller 96 for applying knurling to both edges of the film 100 by embossing is provided downstream of the forced static eliminating device 95. Inside the winding chamber 63, a winding roller 97 for winding the film 100 and a press roller 98 for controlling the tension at the time of winding are provided.

  Next, an example of a method for producing a cellulose acylate film (hereinafter referred to as a film) 100 using the above-described film production facility 50 will be described below. However, the present invention is not limited to the embodiment shown here.

Inside the stock tank 51, the dope 15 is always made uniform by the rotation of the stirrer 71. The dope 15 is appropriately sent by the pump 52 to the filtration device 53 and filtered, and then cast from the casting die 54 onto the casting band 57. The driving of the rotary rollers 55 and 56 is preferably adjusted so that the tension generated in the casting band 57 is 10 ⁴ N / m or more and 10 ⁵ N / m or less. Further, the relative speed difference between the casting band 57 and the rotating rollers 55 and 56 is adjusted to be 0.01 m / min or less. The speed fluctuation of the casting band 57 is preferably 0.5% or less, and the meandering in the width direction when the casting band 57 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 57 is provided, and feedback control is performed using a position controller (not shown) of the casting band 57 based on the measured value. It is more preferable to adjust the position of the casting band 57 by performing the above.

  The casting band 57 located immediately below the casting die 54 is preferably adjusted so that the positional fluctuation in the vertical direction accompanying the rotation of the rotary roller 56 is 200 μm or less. The temperature of the casting chamber 74 is preferably set to −10 ° C. or more and 57 ° C. or less by the temperature control equipment 75. The solvent evaporated inside the casting chamber 74 is liquefied by the condenser 76 and then recovered by the recovery device 77 and reused as a dope preparation solvent.

  A casting bead is formed from the casting die 54 to the casting band 57, and a casting film 80 is formed on the casting band 57. The temperature of the dope 18 at the time of casting is preferably −10 ° C. or more and 57 ° C. or less. At this time, in order to stabilize the casting bead by the decompression chamber 78, the casting bead back surface is preferably decompressed in the range of −2000 Pa to −10 Pa from the front surface.

  The casting film 80 is moved as the casting band 57 travels. At this time, evaporation of the solvent in the casting film 80 is promoted by the drying air being applied to the casting film 80 by the air blowing ports 81 to 83.

  After drying of the casting film 80 is promoted to become self-supporting, the casting film 80 is peeled off from the casting band 57 as the wet film 101 while being supported by the peeling roller 102. The residual solvent amount of the wet film 101 at the time of stripping is preferably 20% by mass or more and 250% by mass or less based on the solid content. While the wet film 101 is transported while being supported by a large number of rollers 90 a in the transfer section 90, drying is accelerated by the drying air from the blower 91. At this time, the temperature of the drying air is preferably 20 ° C. or higher and 250 ° C. or lower. In the transfer section 90, when the rotational speed of the downstream roller among the plurality of rollers 90a is made faster than that of the upstream roller, it is possible to apply a draw tension to the wet film 101.

  Then, the wet film 101 is conveyed to the tenter dryer 58. In the tenter dryer 58, both ends of the wet film 101 are gripped by clips and dried while being stretched in the width direction while being conveyed. At this time, if the inside of the tenter dryer 58 is divided into a plurality of sections and the drying conditions are appropriately adjusted such as different temperatures for each section, the drying of the wet film 101 can be further promoted without causing wrinkles and wrinkles. It is preferable because it is possible. In the tenter dryer 58, it is preferable that at least one of the casting direction and the width direction of the wet film 101 is stretched by 0.5% or more and 300% or less. Thereby, since the effect which improves the orientation of the wet film 101 is acquired, the film 100 which shows the outstanding retardation value can be obtained.

  The wet film 101 is dried to a predetermined residual solvent amount by the tenter dryer 58 and then sent out downstream as a film 100. Both end portions of the film 100 are cut by the ear-cutting device 60. The cut side end portion is sent to a crusher 92 by a cutter blower (not shown), and then crushed into chips. In addition, since this chip is reused for dope preparation, cost reduction can be achieved. Although the cutting process of both side edges of the film can be omitted, since both sides of the film are often damaged by grip marks or excessive drying, the film is peeled off from the casting band 57 as the wet film 101. It is preferable to carry out either after the film is wound or until the film 100 is wound up.

  The film 100 whose both ends are cut is sent to the drying chamber 61, and drying is further promoted. Although the temperature inside the drying chamber 61 is not specifically limited, It is preferable that it is the range of 50 to 160 degreeC. In the drying chamber 61, the film 100 is conveyed while being wound around a roller 93. The solvent gas generated at this time is adsorbed and recovered by the adsorption / recovery device 94, and then the solvent component is removed, and the solvent gas is blown into the drying chamber 61 as dry air again. The drying chamber 61 is more preferably divided into a plurality of compartments in order to change the drying temperature. Further, if a preliminary drying chamber (not shown) is provided between the ear-clipping device 60 and the drying chamber 61 to preliminarily dry the film 100, the film temperature can be prevented from increasing rapidly in the drying chamber 61. 100 shape changes can be further suppressed.

  The film 100 sent to the cooling chamber 62 is cooled to approximately room temperature. When a humidity control chamber (not shown) is provided between the drying chamber 61 and the cooling chamber 62 and air adjusted to a desired humidity and temperature is blown onto the film 100 in the humidity control chamber, the film 100 This is preferable because curling can occur and winding failure during winding can be suppressed.

  Then, the charged voltage while the film 100 is being transported is adjusted by a forced static eliminator (static charge bar) 95 to be within a predetermined range (for example, -3 kV or more and +3 kV or less). Subsequently, knurling is applied to both edges of the film 100 by embossing by the knurling application roller 96. At this time, the unevenness of the knurled portion is preferably 1 μm or more and 200 μm or less.

  Finally, in the winding chamber 63, the film 100 is wound around the winding roller 97 while a desired tension is applied by the press roller 98. At the time of winding, it is more preferable that the film 100 can be wound up without wrinkles if the applied tension is gradually changed from the start to the end of winding. Moreover, it is preferable that the film 100 wound up shall be at least 100 m or more in the longitudinal direction. The width of the film 100 is preferably 600 mm or more, and more preferably 1400 mm or more and 1800 mm or less. However, the present invention can obtain an effect even when it is larger than 1800 mm. Note that the present invention is also applied when manufacturing a thin film 100 having a thickness of 15 μm or more and 100 μm or less when completed.

  In the solution casting method of the present invention, when casting the dope, two or more kinds of dopes can be simultaneously laminated co-casting or sequentially laminated co-casting. 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% or more and 30% or less of the total film thickness of the film composed of multiple layers by co-casting. . 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 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, decompression chamber, support structure, co-casting, peeling method, stretching, drying conditions of each process, handling method, curl, winding method after flatness correction, solvent recovery method, film recovery method Until now, it is described in detail in paragraphs [0617] to [0889] of JP-A-2005-104148, and these descriptions can also 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, and these descriptions are also applied to the present invention. Can do.

[surface treatment]
In the above-mentioned cellulose acylate film, it is preferable that at least one surface 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 above-described 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. As the functional layer, it is preferable to provide at least one of an antistatic layer, a cured resin layer, an antireflection layer, an easy adhesion layer, an antiglare layer, and an optical compensation layer.

This functional layer preferably contains at least one surfactant in the range of 0.1 mg / m ^{2 to} 1000 mg / m ² . Further, the functional layers preferably contain at least one sort of plasticizers in the 0.1 mg / m ² or more 1000 mg / m ² or less. Furthermore, the functional layer preferably contains at least one kind of matting agent in the range of 0.1 mg / m ^{2 to} 1000 mg / m ² . Furthermore, it is preferable that the functional layer contains 1 mg / m ² or more and 1000 mg / m ² or less of at least one antistatic agent. In addition to the above, the method for applying a surface-treated functional layer for realizing various functions and properties on cellulose acylate film is described in paragraphs [0890] to [1087] of JP-A-2005-104148. Detailed conditions and methods are also described, and these descriptions can also be applied to the present invention.

(Use)
The above-mentioned cellulose acylate film is particularly useful as a polarizing plate protective film. For example, a liquid crystal display device can be manufactured by bonding a polarizing plate in which a cellulose acylate film is bonded to a polarizer to a liquid crystal layer. In addition, arrangement | positioning with a liquid crystal layer and a polarizing plate is not limited, It can be set as well-known various arrangement | positioning. 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, but this method is also applicable to the present invention. can do. The application also describes a cellulose acylate film provided with an optically anisotropic layer and a cellulose acylate film provided with antireflection and antiglare functions. Furthermore, the use as an optical compensation film is also described as a biaxial cellulose acylate film imparting appropriate optical performance. This is described in detail in paragraphs [1088] to [1265] of JP-A-2005-104148, such as being able to be used in combination with a polarizing plate protective film. The invention can also be applied.

  In addition, the cellulose triacetate film (TAC film) obtained by the present invention is excellent in optical properties, so that it can be used as a polarizing plate protective film or a base film of a photographic photosensitive material, and can be used as a field of view for liquid crystal display devices for television applications. It can also be used as an optical compensation film for improving angular dependence. Especially, it is effective for the use which also serves as the protective film of a polarizing plate.

  Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to the embodiment shown here. Further, the manufacturing method and manufacturing conditions are shown in detail only in the first embodiment, and the description is omitted in the second to fourth embodiments. Examples 2 to 4 are comparative examples with respect to Example 1.

The formulation relating to the preparation of the polymer solution (dope) used in this example is shown below.
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-chlorobenzotriazole 0.3 parts by mass of citric acid ester mixture (citric acid, Ethyl ester, diethyl ester, triethyl ester mixture) 0.006 parts by weight fine particles (silicon dioxide (average particle size 15 nm), Mohs hardness: about 7) 0.05 parts by weight

  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 had 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 heating value 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.

  According to the dope manufacturing process 10 shown in FIG. 1, the dope 15 was prepared using the above-described raw materials and the extruder 20 shown in FIG.

  An appropriate amount of the swelling liquid 16 prepared in advance and stored in the tank 21 was put into the cylinder 24, and the screw 22 was rotated at a high speed to perform stirring and mixing. Before introducing the swelling liquid 16 into the cylinder 24, a hydrofluoroether at −90 ° C. is fed into the jacket 23 as a refrigerant, and the first flow rate at the extruder outlet 20a is adjusted while adjusting the flow rate of the refrigerant. The temperature of the dope 17 was controlled. In Example 1, the average temperature of the first dope 17 in the vicinity of the extruder outlet 20a was −70 ° C. The amplitude of this average temperature was ± 2 ° C.

  Further, the temperature control near the extruder outlet 20a is performed by constantly measuring the temperature of the first dope 17 with the thermometer 36 and adjusting the refrigerant circulator 25 with the first controller 26 based on the measured temperature value. It was. Furthermore, the second controller 27 is provided inside the extruder 20 and the refrigerant circulator 25 is adjusted based on the rotational speed while measuring the rotational speed of the screw 22 so that the temperature of the first dope 17 is substantially constant. I managed to be.

  The first dope 17 that was stirred and mixed and adjusted to have a substantially constant temperature was extruded from the extruder outlet 20a to a cooler (not shown), where cooling dissolution was promoted (cooling step 12). At this time, the extrusion flow rate of the first dope 17 was 1.5 L / min. And the cooled 1st dope 17 was sent out to the heating machine (not shown), and the mixed solvent etc. were fully dissolved by heating, and it was set as the 2nd dope 18 (heating process 13). Finally, after the second dope 18 was brought to about room temperature by a temperature controller (not shown), impurities were removed by filtering with a filter (not shown) to obtain a dope 15 (filtering step 14). The dope 15 was very excellent in solubility (solubility ◎) such that almost no insoluble components could be confirmed.

  The film 100 was manufactured using the film manufacturing equipment 50 shown in FIG. By rotating the stirrer 71 inside the stock tank 51, the dope 15 that has been kept uniform is sent to the filtering device 53 by the pump 52 and filtered, and then flows from the casting die 54 onto the casting band 57. Extended. At this time, the flow rate is adjusted from the discharge port of the casting die 54 so that the width is 1.8 m and the film thickness of the dried film is 80 μm, and the casting width is 1700 mm and the dope 15 is cast. did. The casting die 54 was provided with a jacket (not shown) capable of controlling the temperature by supplying a heat transfer medium therein, and the temperature of the dope 15 was adjusted to 36 ° C.

  The casting die 54 was a coat hanger type die having thickness adjusting bolts provided at a pitch of 20 mm and having an automatic thickness adjusting mechanism using a heat bolt. The heat bolt can also set a profile according to the amount of liquid delivered by the pump 52 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 manufacturing facility 50. 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. In addition, a decompression chamber 78 was installed on the primary side of the casting die 54. The dope 15 was cast while stabilizing the casting bead by adjusting the degree of decompression of the decompression chamber 78.

As the material of the casting die 54, precipitation hardening type stainless steel having a thermal expansion coefficient of 2 × 10 ⁻⁵ (° C. ⁻¹ ) or less was used. The finishing precision of the liquid contact surface of the casting die 54 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 54 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 15 to be cast from being locally dried and solidified at the discharge port of the casting die 54, 86.5 parts by mass of dichloromethane and 13 parts by mass of acetone are used as a solvent for solubilizing the dope 15. The mixed solvent A in which 0.5 part by mass of 1-butanol was mixed was prepared, and 0.5 ml / min was supplied to each interface between the both 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.

  Drying air was blown from the blowing ports 81 to 83 toward the casting film 80 formed on the casting band 57 so as to go in the transport direction, thereby promoting drying. After the casting film 80 was dried and became self-supporting, the casting film 80 was peeled off from the casting band 57 by the peeling roller 102 to obtain a wet film 101. The oxygen concentration in the dry atmosphere on the casting band 57 is maintained at 5 vol% by substituting air with nitrogen gas. Further, the solvent inside the casting chamber 74 is replaced with a condenser (condenser) 76. The outlet temperature was set at −10 ° C. and condensed.

  While the wet film 101 was conveyed through the roller 90 a of the crossing section 90, drying air was blown from the blower 91 to accelerate drying, and the dried film was sent to the tenter dryer 58. In the transfer part 90, 40 ° C. dry air was blown from the blower 91 while transporting with a tension of about 30 N applied to the longitudinal direction of the wet film 101. In the tenter dryer 58, the wet film 101 was conveyed while being stretched in the width direction in a state where both end portions of the wet film 101 were gripped by the tenter clip. The interior of the tenter dryer 58 was divided into three sections, and the drying air temperature in each section was set to 90 ° C., 110 ° C., and 120 ° C. from the upstream side. At this time, the gas composition of the drying air was set to a saturated gas concentration at −10 ° C. Then, at the outlet of the tenter dryer 58, the film was dried until the residual solvent amount became 7% by mass to obtain a film 100.

Within 30 seconds from the exit of the tenter dryer 58, the 50 mm ears on both sides of the film 100 were cut using an NT-type cutter as the ear-cutting device 60. At this time, the cut ears were blown to a crusher 92 by a cutter blower (not shown) and crushed into chips having an average of about 80 mm ² , and this chip was used again as a dope preparation raw material. The air in the tenter dryer 58 was replaced with nitrogen gas, and the oxygen concentration in the dry atmosphere was maintained at 5 vol%. In addition, the film 100 was preheated in a predrying chamber (not shown) to which drying air at 100 ° C. was supplied before being dried at a high temperature in the drying chamber 61 described later.

  The film 100 was dried at a high temperature in the drying chamber 61. The drying chamber 61 was divided into four sections, and drying air at 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 100 by the roller 93 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 (film winding center angle) of the roller 93 was 90 degrees and 180 degrees (exaggerated in FIG. 2). The material of the roller 93 was made of aluminum or carbon steel, and hard chrome plating was applied to the surface. Moreover, the surface shape of the roller 93 used was a flat surface and a surface formed by matting by blasting. Film position fluctuations due to the rotation of the roller 93 were all 50 μm or less.

  The solvent gas contained in the drying air was adsorbed and recovered using an adsorption recovery device 94. 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 plasticizer, UV absorber, and other high-boiling substances in addition to solvent gas, so these were removed by a cooler and a pre-adsorber that were cooled and removed, and were recycled and used. And adsorption / desorption conditions were set so that VOC (volatile organic compound) in the outdoor exhaust gas was finally 10 ppm or less. Moreover, the solvent amount collect | recovered by 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 100 was conveyed to the 1st humidity control chamber (not shown). A drying air of 110 ° C. was sent out to the transition part between the drying chamber 61 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. Furthermore, the film 100 was conveyed to the 2nd humidity control chamber (not shown) which suppresses generation | occurrence | production of the curl of the film 100. FIG. In the second humidity control chamber, air of 90 ° C. and humidity 70% was sent directly to the film 100.

  The film 100 after humidity control was cooled to 30 ° C. or lower in the cooling chamber 62, and then the ears were cut again at both ends with an ear-cutting device (not shown). In addition, a forced static elimination device (static elimination bar) 95 was installed so that the charged voltage of the film 100 being conveyed was always in the range of −3 to +3 kV. Further, knurling was applied to both ends of the film 100 by a knurling roller 96. The knurling was imparted by embossing from one side of the film 100. 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 100.

  Finally, the film 100 was conveyed to the winding chamber 63. The winding chamber 63 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 63 so that the charged voltage of the film 100 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 97 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. Further, the fluctuation width (sometimes referred to as an 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 97 was set to 400 m. The pressing pressure of the press roller 98 against the winding roller 97 was set to 50 N / m. The temperature of the film 100 during winding was 25 ° C., the water content was 1.4% by mass, and the residual solvent amount was 0.3% by mass.

  A film 100 was produced using the dope 15 produced by the same preparation method as in Example 1 and the film production facility 50. However, in the extruder 20, hydrofluoroether adjusted to −90 ° C. was supplied as a refrigerant to the inside of the jacket 23 as in Example 1, but the operation was performed without adjusting the flow rate. . As a result, the average temperature of the first dope 17 in the vicinity of the extruder outlet 20a was −70 ° C., and the average temperature amplitude was ± 6 ° C. When the solubility of the obtained dope 15 was confirmed, Although there was no problem in film production (solubility ○), the undissolved components were confirmed slightly in comparison with Example 1.

A film 100 was produced using the dope 15 produced by the same preparation method as in Example 1 and the film production facility 50. However, in the extruder 20, when an operation was performed while supplying a CFC refrigerant R23 (CHF ₃ ) adjusted to −90 ° C. as a refrigerant to the inside of the jacket 23 and adjusting the flow rate, the extruder 20 The average temperature of the first dope 17 in the vicinity of the outlet 20a was −50 ° C., but the amplitude of the average temperature was ± 10 ° C. When the solubility of the obtained dope 15 was confirmed, the undissolved component was confirmed. (Solubility x).

  A film 100 was produced using the dope 15 produced by the same preparation method as in Example 1 and the film production facility 50. However, in the extruder 20, water adjusted to 25 ° C. was supplied as a refrigerant to the inside of the jacket 23, and the operation was performed without adjusting the flow rate. As a result, the average temperature of the first dope 17 in the vicinity of the extruder outlet 20a was 25 ° C., and the amplitude of the average temperature was ± 5 ° C. Moreover, when the solubility of the obtained dope 15 was confirmed, a very large amount of undissolved components were confirmed (solubility xx).

  From the results of the above Examples, in Examples 1 and 2 in which the refrigerant adjusted to a predetermined temperature was supplied to the extruder 20 used when preparing the dope 15, and the operation was performed while adjusting the flow rate. A dope 15 exhibiting excellent solubility could be obtained. However, in contrast to Example 1, in Example 2, since the amplitude of the average temperature is large, it is effective to always manage the circulating flow rate of the refrigerant in order to obtain the dope 15 having a small average temperature variation. It turns out that. On the other hand, in Example 3, the refrigerant adjusted to the same temperature as in Examples 1 and 2 in which the dope 15 having excellent solubility was obtained, and the dope was prepared while adjusting the flow rate. However, the dope 15 showing satisfactory solubility could not be obtained. Therefore, it was confirmed that the kind of the refrigerant affects the solubility of the dope 15. Further, in Example 4, a very large amount of undissolved residue was present in the prepared dope 15. As a cause of this, in Example 4, a refrigerant whose temperature was adjusted to below zero was used in the other examples, whereas water adjusted to 25 ° C. was used as a refrigerant. It is thought that it was not possible.

  As described above, in the dope preparation method for preparing a dope containing a polymer and a solvent, a cooling medium is provided in the flow path using an extruder having a screw having a rotating function and a jacket having a flow path formed therein. It was confirmed that the polymer can be sufficiently dissolved in the solvent by supplying the polymer and the solvent after rotating the extruder and then rotating the screw. It was also confirmed that the temperature of the dope discharged from the extruder can be made substantially constant by adjusting the flow rate of the cooling medium according to the number of rotations of the screw.

It is process drawing which shows the flow of the dope manufacturing process used for this invention. It is the schematic of the extruder used for this invention. It is the schematic of the film manufacturing equipment used for this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Dope manufacturing process 11 Cooling melt | dissolution process 15 Dope 20 Single screw extruder 20a Extruder exit 22 Screw 23 Jacket 25 Refrigerant circulating machine 35 Refrigerant 50 Film production equipment 100 Film

Claims (6)

In a dope preparation method for preparing a dope comprising a polymer and a solvent,
Using an extruder having a screw with a rotating function and a jacket formed with a flow path,
Cooling dissolution in which the polymer is dissolved in the solvent by rotating the screw after supplying the polymer and the solvent into the extruder cooled by flowing a cooling medium through the flow path. Having a process,
A method for preparing a dope characterized in that the temperature of the dope discharged from the extruder is made substantially constant by adjusting the flow rate of the cooling medium according to the number of rotations of the screw.   The dope preparation method according to claim 1, wherein the temperature of the cooling medium is set to −120 ° C. or more and 0 ° C. or less.   3. The dope preparation method according to claim 1, wherein at least one of methanol, dichloromethane, fluorocarbon, and hydrofluoroether is used as the cooling medium.   4. The average temperature T (° C.) of the dope when discharged from the extruder is substantially constant in a range of −100 ° C. to 0 ° C. 4. Dope preparation method.   5. The temperature range of the dope is not less than (T−5) ° C. and not more than (T + 5) ° C. with respect to the average dope temperature T (° C.) inside the extruder. Dope preparation method. The dope preparation method according to any one of claims 1 to 5, wherein the polymer is cellulose acylate.

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