JP2010046911A - Tentering machine and solution film-forming method using the same - Google Patents

Abstract

An object of the present invention is to eliminate inconvenience caused by holding a wet film with a clip that becomes hot.
A tenter device 10 extends a width direction while conveying a wet film 16 in one direction in a sealed casing 15 by infinite circulation of a pair of left and right chains 22 and 23 provided with a number of clips 45. . In stretching, the drying mechanism 12 blows dry air to raise the temperature of the wet film 16 stepwise and dry. The left and right chains 22 and 23 are guided by return guide portions 20c and 21c provided outside the casing 15 after gripping the wet film 16 by the transport guide portions 20a and 21a, and are opposite to the transport direction. In the direction and returned to the inside of the casing 15 again. Clip cooling mechanisms 13 and 14 are provided in the return guide portions 20c and 21c. The clip cooling mechanisms 13 and 14 cool the clip 45 that is heated in the casing outside the casing.
[Selection] Figure 1

Description

  The present invention relates to a tenter device for transporting a film in one direction by gripping both ends of the film with a plurality of clips provided on an endless chain, and blowing the drying air in the meantime to stretch the film in the width direction while drying. The present invention relates to a solution casting method using

  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 an optical film.

  Such a polymer film is mainly produced by a solution casting method. This solution casting method is roughly classified into a dope manufacturing method and a solution casting method. In the dope manufacturing method, a polymer solution (dope) containing a polymer such as cellulose acylate and a solvent is produced. In the solution casting method, a cast film formed by casting on a support on which a polymer solution runs is peeled off from the support to form a wet film, and then the wet film is dried while being stretched in the width direction. To make a polymer film.

  In the solution casting method, a tenter device is used to dry a wet film while stretching it in the width direction (Patent Document 1). The tenter device includes a pair of guide rails, a pair of chains guided by each guide rail, a plurality of clip groups attached to each chain at a predetermined pitch, and a drying unit that blows drying air from above and below the film surface. These are arranged inside the closed chamber by a casing so as not to leak harmful solvent gas such as methylene claloid to the outside. The casing is provided with a film inlet for supplying a wet film and a film outlet for discharging the dried wet film. Although solvent gas leaks also from these entrances and exits, since this casing itself is arrange | positioned in a building with much higher sealing property, solvent gas does not leak outside.

  Each chain is wound between a driving sprocket provided on the film outlet side and a driven sprocket provided on the film inlet side, and is arranged to face each other. The drive sprocket rotates so as to pull the opposite inner chain (forward chain) from the film inlet toward the film outlet. Each guide rail is disposed between the driving and driven sprockets, and includes an outward path guide for guiding the forward movement side chain and a return path guide for guiding the returning double movement side chain. And in order to make it extend | stretch in the width direction, a pair of guide rail is distribute | arranged so that rail width may be gradually expanded toward a film exit from a film entrance.

  On the driven sprocket side, when each clip moves from the return path guide to the forward path guide, the clip is opened to the open position, and preparations are made for gripping the wet film supplied from the film inlet. In the forward guide, the clip is moved to the closed position to grip the wet film. When traveling on the forward guide, the clip is maintained in the closed position, and the wet film is transported. At the position of the drive sprocket that turns back from the forward path guide to the backward path guide, the clip moves to the open position again, and the gripping of the wet film is released. Thereby, the wet film is conveyed toward the film exit. During this conveyance, drying air is blown stepwise by the drying unit. The drying section is divided into at least three sections in the film transport direction, for example, a preheating zone, a stretching zone, and a stretching relaxation zone, and an optimum drying temperature is set for each zone.

  Optical films are required to have a more uniform retardation value and thickness direction control of the film thickness. For this reason, when drying in a drying section, hot air is blown so that the temperature distribution of the wet film is uniform in the width direction (Patent Document 2).

  By the way, when the wet film is heated so as to be uniform in the width direction, the clip also becomes high temperature under the influence of the drying air. If the clip is at a high temperature when returning to the film entrance side again, when the wet film is gripped, foaming may occur at the gripped portion and its vicinity, and there is a possibility that the grip cannot be performed reliably. Therefore, the clip is cooled by blowing cooling air onto the clip while the clip passes through the return path guide.

  In the tenter device of Patent Document 1, as described in the paragraphs [0022] to [0025] of the specification, when the drying air is applied to the clip for a long time, the opening / closing operation of the clip may be lowered. A cover that prevents the air from being sprayed on the clip is provided throughout the area between the grip start position and the grip release position, and fresh air is supplied into the cover to prevent dry air from entering the cover. Yes.

JP 2006-116938 A JP 2000-313060 A

  By the way, in the tenter device described in Patent Document 1, since fresh air is sent into the cover provided in the entire region between the grip start position and the grip release position, the cover becomes wet as a cooling source with respect to the surroundings. It was found that the temperature on both sides of the film was lowered. It was also found that this phenomenon appears more prominently with wider films.

  The present invention is to solve the above-described problems, and provides a tenter device capable of uniformly drying a wide film in the width direction and a solution casting method using the tenter device.

  In order to achieve the above object, in the present invention, a cooling duct is provided so as to cover a part or all of a pair of return guide portions that guide an endless chain fed out of the casing outside the casing, and the cooling duct is cooled. A wind is sent in to cool the clips of each endless chain.

  By the way, endless chains wound around drive sprockets and driven sprockets provided at both ends of the conveyance path provided in the casing are circulated endlessly in a pair, and the film is gripped by the parts facing each other in the conveyance direction. In conventional tenters that transport toward the end of the chain, the endless chain take-up has a structure that stretches the endless chain by moving the driven sprocket upstream of the transport direction in the film transport direction. If the adjustment is shifted left and right, the grip start position of the clip that first grips the film is also shifted left and right in the transport direction (axial direction). In this way, when the film is gripped on the left and right sides, stretching unevenness may occur.

  Therefore, it is desirable to have a structure in which the take-up of each endless chain is stretched in the film width direction. Each endless chain is preferably wound around at least four sprockets. For example, a drive sprocket provided on the downstream side in the conveyance direction of the conveyance path in the casing and a driven sprocket provided on the upstream side, and two driven sprockets provided on the upstream and downstream sides in the conveyance direction outside the casing; It is preferable to comprise. In this case, it is preferable that the driven sprocket provided outside the casing and upstream of the conveying direction is a tension sprocket that urges the endless chain in the film width direction.

  In the solution casting method, it is preferable that the polymer is cellulose acylate.

  In the present invention, a pair of return chains provided in a path between a pair of endless chains provided with a plurality of clips for gripping both ends of a wide film inside the casing, after releasing the grip, and returned to the inside of the casing. Since the cooling ducts are provided in the guide portions and the cooling air is sent into these cooling ducts, the clips of the left and right endless chains can be cooled outside the casing. Thus, unlike the conventional case, the cooling source is not disposed in the casing, and the temperature distribution in the film width direction in the casing can be kept uniform.

  In addition, since the driven sprocket provided outside the casing is moved in the film width direction to adjust the chain tension, the grip start position does not shift from side to side even if the chain is stretched. Generation of unevenness is suppressed.

  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.

  As shown in FIG. 1, the tenter device 10 includes a transverse stretching mechanism 11, a drying mechanism 12, and clip cooling mechanisms 13 and 14, and the transverse stretching of the wet film 16 in a room sealed by a heat insulating casing 15. I do. The clip cooling mechanisms 13 and 14 are arranged outside the casing 15.

  The casing 15 is provided with a film inlet 17 through which the wet film 16 is supplied and a film outlet 18 through which the wet film 16 is discharged. The wet film 16 is supplied from the film inlet 17, transported along the transport path 19, and discharged from the film outlet 18.

  The lateral stretching mechanism 11 includes a left rail 20, a right rail 21, left and right chains (endless chains) 22 and 23 guided by the rails 20 and 21, and the like. The right rail 21 is arranged along a locus in which the right chain 22 is infinitely circulated in a substantially rectangular shape by the four driven sprockets 24 to 27, and includes four conveyance guide portions 21a corresponding to each side of the rectangular shape, It comprises a guide portion 21b, a return guide portion 21c, and a feeding guide portion 21d. The left rail 20 is also arranged along a trajectory that causes the left chain 22 to endlessly circulate in a substantially rectangular shape by the four sprockets 32 to 35, and, like the right rail 21, the conveyance guide portion 20 a, the delivery guide portion 20 b, and the return guide. It consists of a part 20c and a feeding guide part 20d.

  The conveyance guide portions 20a and 21a of the left rail 20 and the right rail 21 are arranged to face each other, and the wet film 16 is conveyed between them. The rail widths of the transport guide portions 20a and 21a are arranged so as to gradually widen from the film inlet 17 toward the film outlet 18 in order to stretch the wet film 16 laterally. These conveyance guide parts 20a and 21a have a structure in which a plurality of guide parts are connected in series, and each guide part is attached so as to be movable in the film width direction. The rail width is changed according to the width before the wet film 16 is stretched or according to the stretch rate of the wet film 16.

  The width of the wet film 16 before stretching is, for example, preferably 1300 mm or more and 3000 mm or less, and more preferably 1300 mm or more and 2300 mm or less. The stretching ratio is preferably in the range of 1.1 to 1.8 times the width of the wet film 16 before stretching, and more preferably in the range of 1.1 to 1.5 times. . The thickness of the wet film 16 in this case is preferably a thin film of, for example, 15 μm or more and 100 μm or less, and the linear length along the transport direction of the transport guide portions 20a and 21a is, for example, approximately 10 m to 50 m. And a length of 25 m to 35 m is more preferable.

  Drive sprockets 25 and 32 are arranged between the conveyance guide portions 20a and 21a and the delivery guide portions 20b and 21b (corner portions). The delivery guide portions 20 b and 21 b are arranged substantially parallel to the film width direction, and guide the chains 22 and 23 toward the outside of the casing 15 through the chain outlets 40 and 41 provided in the casing 15. The pair of drive sprockets 25 and 32 rotate in synchronization with a motor and gear train (not shown). Moreover, the conveyance speed of the wet film 16 is 200 m / min or more, for example.

  Driven sprockets 26 and 33 are arranged between the delivery guide portions 20b and 21b and the return guide portions 20c and 21c (corner portions). The return guide portions 20c and 21c are provided outside the casing 15, and guide the chains 22 and 23 sent out by the driven sprockets 26 and 33 in a direction opposite to the conveying direction.

  Driven sprockets 24 and 34 are arranged between the return guide portions 20c and 21c and the feeding guide portions 20d and 21d (corner portions). The feeding guide portions 20 d and 21 d are arranged substantially parallel to the film width direction, and guide the chains 22 and 23 toward the inside of the casing 15 through chain inlets 42 and 43 provided in the casing 15.

  Driven sprockets 24 and 35 are arranged between the feeding guide parts 20d and 21d and the conveyance guide parts 20a and 21a (corner parts), and the driven sprockets 24 and 35 convey the returned chains 22 and 23 again. It feeds into the guide parts 20a and 21a.

  Each chain 22 and 23 is provided with a plurality of clips 45 for gripping the wet film 16. Each clip 45 is movable between the nip position and the nip release position, and is maintained at the nip position by, for example, its own weight or the urging force of the urging means. Each clip 45 nips the wet film 16 at the grip start position 46 on the driven sprockets 24 and 35 side of the transport guide portions 20a and 21a at the same time in the transport direction and releases the grip on the drive sprockets 25 and 32 side. At the position 47, the nip of the wet film 16 is released simultaneously on the left and right.

  In this embodiment, since only the right rail 21 is expanded with respect to the left rail 20 and the wet film 16 is extended in the width direction, the lengths of the transport guide portions 20a and 21a are different on the left and right. In order to configure the left and right clips 45 to return simultaneously to the grip start position 46, the length of any one of the feeding guide portions 20d and 21d, the return guide portions 20c and 21c, and the feeding guide portions 20d and 21d The lengths of the left and right chains 22 and 23 are the same by changing the length of the left and right chains.

  The driven sprockets 27 and 34 provided between the return guide portions 20c and 21c and the feeding guide portions 20d and 21d are movable in the film width direction, and the chain is stretched by a biasing means such as a spring 48. It is biased towards the direction. As a result, a constant tension can be individually applied without changing the length of the left and right chains 22 and 23 in the conveying direction, so that the gripping of the clip 45 at the gripping start position 46 is separated from the left and right. Can be solved reliably. The chain tension direction is not limited to the film width direction, and the distance between the drive sprockets 25 and 32 and the driven sprockets 24 and 35 may not be changed by take-up. For example, the driven sprockets 27 and 34 are connected to the driven sprocket 24. , 35 may be away from each other. Further, each of the left and right chains 22 and 23 is wound around four sprockets and endlessly circulated, but the number of sprockets for endless circulation is not limited to four, and may be four or more.

  The drying mechanism 12 dries the wet film 16 and includes four drying units 53 to 56. These drying sections 53 to 56 are for setting the film temperature to an appropriate temperature in the range of, for example, 140 ° C. to 200 ° C. from the film inlet 17 to the film outlet 18. A plurality of blower heads 57 that are long in the film width direction are arranged at a predetermined pitch in the transport direction. Each blower head 57 is arranged in parallel with the film surface above and below the conveyance path 19, and blows dry air from a plurality of outlets provided at a predetermined pitch in the width direction on the upper and lower surfaces of the wet film 16. The solvent gas volatilizes from the wet film 16 by drying. The casing 15 has an action of preventing the gas from leaking outside in addition to the heat insulation action.

  The clip cooling mechanisms 13 and 14 are formed long along the return guide portions 20c and 21c, and send the cooling air sent from the suction port 58 provided substantially at the center in the longitudinal direction along the return guide portions 20c and 21c. The cooling air is discharged to the outside from the discharge ports 59 and 60 provided at both ends in the longitudinal direction, and the clip 45 passing through the return guide portions 20c and 21c is cooled.

  As shown in FIG. 2, an inlet opening member 50 is attached to each of the left and right driven sprockets 24, 35 on the film inlet 17 side of the transport guides 20a, 21a. The inlet opening member 50 moves the clip 45 to the nip release position with the effort of the grip start position 46 and allows both sides of the wet film 16 to enter the nip position. Conversely, outlet opening members 51 are attached to the left and right drive sprockets 25, 32 at the film outlet 18, respectively. The outlet opening member 51 is provided only in the rear range including the grip release position, and sequentially displaces the clip 45 to the nip release position.

  The chain inlets 42 and 43 are provided with an air curtain mechanism 62 outside the frontage. Although not shown, an air curtain mechanism 62 is also provided outside the frontage at the chain outlets 40 and 41. These air curtain mechanisms 62 blow off an air curtain flow in the downward direction and block the outside air wind. The configuration is not limited to the air curtain mechanism 62, and an elastic curtain made of a material such as urethane may be provided and blocked.

  As shown in FIG. 3, the clip cooling mechanisms 13 and 14 include a cooling duct 65, a supply duct 66, a blower mechanism that sends cooling air (not shown) into the supply duct 66, and the like. The cooling duct 65 is formed in a cover shape that covers all or part of the return guide portion 21c. A supply duct 66 is connected to the suction port 58, and cooling air supplied from the supply duct 66 flows into the cooling duct 65 and cools the clip 45 passing therethrough. The cooling air is at a lower temperature than the drying air blown from the drying units 53 to 56. Thus, when the clip 45 comes to the grip start position 46 of the transport guide portions 20a and 21a, the cooling is performed at a temperature higher than the temperature raised by the drying mechanism 12, so that foaming occurs at and near the portion gripped by the clip 45. Inconveniences such as occurrence can be reliably prevented. Moreover, since the cooling mechanisms 13 and 14 cool the clip 45 outside the casing 15, the inside of the casing 15 can be performed without any influence. For this reason, the problem of lowering the temperature of the wet film 16 extending inside the casing 15 can also be eliminated. Note that an air volume adjustment valve 67 is attached to the supply duct 66, and the air volume can be adjusted according to the temperature of the clip 45 after the grip is released.

  As described above, the result of measuring the temperature distribution in the width direction of the wet film in the casing by employing the clip cooling mechanism provided outside the casing is described in the graph shown in FIG.

  In the graph shown in FIG. 4, the horizontal axis indicates the position in the width direction, and the vertical axis indicates the temperature. Reference symbol A shows a graph of the temperature distribution of the wet film 16 stretched by the tenter device 10 of the present embodiment in which the clip cooling mechanisms 13 and 14 are attached to the outside of the casing 15, and reference symbol B indicates the clip cooling mechanism. 1 shows a graph of the temperature distribution of a wet film stretched by a conventional tenter device attached to the inside of the casing. The conventional tenter device here has a configuration in which the return guide portion is arranged inside the casing and next to the conveyance guide portion. As shown in the figure, it was found that the graph indicated by the symbol A has a smaller temperature difference between the both ends with respect to the center in the width direction, and the temperature distribution in the width direction can be made substantially uniform. Moreover, although not shown with a graph etc., it turned out that the film | membrane properties of the width direction, such as a retardation and a film thickness, become uniform.

  Next, the manufacturing method of the said wet film is demonstrated. However, the manufacturing method and manufacturing apparatus described below are examples of the present invention, and the present invention is not limited thereto.

[material]
In the present embodiment, cellulose acylate is used as the polymer, and triacetyl cellulose (TAC) is particularly preferable as the cellulose acylate. Among 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 a ratio in which the hydrogen of the hydroxyl group at the 2-position in the glucose unit is substituted by an acyl group (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. The ratio of hydrogen being substituted by an acyl group (hereinafter referred to as “acyl substitution degree at the 3-position”), DS6 is the ratio of the hydrogen of the hydroxyl group at the 6-position in the glucose unit (hereinafter referred to as “acyl group”). (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, a dope having excellent solubility and low viscosity and good filterability can be produced in a non-chlorine organic solvent.

  Cellulose, which is a raw material of 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, n-butanol, etc., 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 a 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. Also for 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, 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 production method]
First, a dope is manufactured using the above raw materials. First, the solvent is sent from the solvent tank to the dissolution tank. Next, the TAC contained in the hopper is fed into the dissolution tank while being measured. The required amount of the additive solution is fed from the additive tank to the dissolution tank. In addition to the method of sending the additive as a solution, for example, when the additive is liquid at normal temperature, it can be sent to the dissolution tank in the liquid state. Further, when the additive is solid, a method of feeding into the dissolution tank using a hopper or the like is also possible. When a plurality of types of additives are added, a solution in which a plurality of types of additives are dissolved can be placed in the additive tank. Alternatively, a solution in which an additive is dissolved can be put in each of a plurality of additive tanks, and sent to the dissolution tank through independent pipes.

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

  The dissolution tank is provided with a jacket that wraps around its outer surface and a first stirrer that is rotated by a motor. Furthermore, it is preferable that the 2nd stirrer rotated by a motor is attached to the dissolution tank. The first stirrer is preferably provided with anchor blades, and the second stirrer is preferably a dissolver type eccentric stirrer. And the temperature of the dissolution tank is adjusted by flowing a heat transfer medium through the jacket, and the preferred temperature range is -10 ° C to 55 ° C. By appropriately selecting and using the types of the first stirrer and the second stirrer, a swelling liquid in which TAC is swollen in a solvent is obtained.

  The swelling liquid is sent to the heating device by a pump. The heating device is preferably a jacketed pipe, and further preferably has a configuration capable of pressurizing the swelling liquid. By using such a heating apparatus, the dope is obtained by dissolving the solid content in the swelling liquid under heating conditions or under pressure heating conditions. Hereinafter, this method is referred to as a heating dissolution method. In this case, the temperature of the swelling liquid is preferably 50 ° C to 120 ° C. Moreover, the cooling dissolution method which cools a swelling liquid to the temperature of -100 degreeC--30 degreeC can also be performed. TAC can be sufficiently dissolved in a solvent by appropriately selecting the heating dissolution method and the cooling dissolution method. After the dope is brought to about room temperature with a temperature controller, the impurities contained in the dope are removed by filtration with a filtration device. The filtration filter used in the filtration device preferably has an average pore diameter of 100 μm or less. The filtration flow rate is preferably 50 L / hr or more. The dope 83 after filtration is sent to the stock tank 71 in the film production line 70 of FIG. 5 and stored therein.

  By the way, as described above, the method of once preparing the swelling liquid and then using the swelling liquid as a dope increases the time required as the concentration of TAC is increased, which may be problematic in terms of manufacturing cost. . In that case, it is preferable to prepare a dope having a concentration lower than the target concentration and then perform a concentration step for obtaining the target concentration. When using such a method, the dope filtered by the filtration device is sent to the flash device, and a part of the solvent in the dope is evaporated in the flash device. The solvent gas generated by the evaporation is condensed by a condenser (not shown) to become a liquid and recovered by a recovery device. The recovered solvent is regenerated and reused as a solvent for preparing a dope by a regenerator. This reuse is effective in terms of cost.

  Further, the concentrated dope is extracted from the flash device by a pump. Furthermore, it is preferable that a bubble removal process is performed to remove bubbles generated in the dope. As this defoaming method, various known methods are applied, for example, an ultrasonic irradiation method. The dope is then sent to a filtration device to remove foreign matter. In addition, it is preferable that the temperature of dope at the time of filtration is 0 degreeC-200 degreeC. The dope 83 is sent to the stock tank 71 and stored.

  By the above method, the dope whose TAC density | concentration is 5 mass%-40 mass% can be manufactured. More preferably, the TAC concentration is from 15% by mass to 30% by mass, and most preferably from 17% by mass to 25% by mass. The concentration of the additive (mainly 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 is 100% by mass. 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 dope manufacturing methods such as defoaming, paragraph [0517] of JP-A-2005-104148 To [0616] paragraph. These descriptions can also be applied to the present invention.

[Solution casting method]
Next, a method for producing a film using the dope 83 obtained above will be described. FIG. 5 is a schematic view showing a film production line 70. However, the present invention is not limited to the film production line as shown in FIG. The film production line 70 is provided with a stock tank 71, a filtration device 72, a casting die 73, a casting band 75 stretched around rotating rollers 68 and 74, the tenter device 10 of the present invention, and the like. Further, an ear clip device 76, a drying chamber 77, a cooling chamber 78, a winding chamber 79, and the like are arranged.

  A stirrer 81 that is rotated by a motor 80 is attached to the stock tank 71. The stock tank 71 is connected to the casting die 73 via a pump 82 and a filtration device 72.

As a material of the casting die 73, precipitation hardening type stainless steel is preferable, and its thermal expansion coefficient is preferably 2 × 10 ⁻⁵ (° C. ⁻¹ ) or less. And what has corrosion resistance substantially the same as that of SUS21d6 in a forced corrosion test with an electrolyte aqueous solution can be used as the material of the casting die 73, and further, in a mixed solution of dichloromethane, methanol and water for 3 months. Those having corrosion resistance that do not cause pitting (perforation) at the gas-liquid interface even when immersed are used. Furthermore, it is preferable that the casting die 73 is manufactured by grinding a material that has passed one month or more after casting. As a result, the dope 83 flows uniformly in the casting die 73, and streaks and the like are prevented from occurring in the casting film described later. The finishing accuracy of the wetted surface of the casting die 73 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 73 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-contact part of the lip | tip end of the casting die 73, the R shall be 50 micrometers or less over the whole width. Moreover, it is preferable that the shear rate inside the casting die 73 is adjusted to be 1 (1 / sec) to 5000 (1 / sec).

  The width of the casting die 73 is not particularly limited, but is preferably 1.1 to 2.0 times the width of the film as the final product. Moreover, it is preferable to attach a temperature controller (not shown) to the casting die 73 so that the temperature during film formation is maintained at a predetermined temperature. The casting die 73 is preferably a coat hanger type. Furthermore, it is more preferable that thickness adjusting bolts (heat bolts) are provided at predetermined intervals in the width direction of the casting die 73 and the casting die 73 is provided with an automatic thickness adjusting mechanism using heat bolts. The heat bolt is preferably formed by setting a profile according to the amount of pump 82 (preferably a high precision gear pump) according to a preset program. Further, feedback control may be performed by an adjustment program based on a profile of a thickness meter (for example, an infrared thickness meter) (not shown) in the film production line 70. The thickness difference between any two points in the width direction of the product film, excluding the casting edge, is adjusted to within 1 μm, and the difference between the minimum value and the maximum value in the width direction thickness is adjusted to 3 μm or less. Preferably, adjusting to 2 μm or less is more preferable. Moreover, 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 73. 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 ceramics are used as the cured film, it is preferable to use a ceramic that can be ground, has a low porosity, is not brittle, has good corrosion resistance, has good adhesion to the casting die 73, and does not have adhesion to the dope 83. Specific examples include tungsten carbide (WC), Al ₂ O ₃ , TiN, Cr ₂ O _{3 and the} like, and WC is particularly preferable. The 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 73 in order to prevent the flowing out dope 83 from being locally dried and solidified. Further, a solvent for solubilizing the dope 83 (for example, a mixed solvent of 86.5 parts by mass of dichloromethane, 13 parts by mass of methanol, and 0.5 parts by mass of n-butanol) It is preferable to supply to the peripheral part of the three-phase contact line which external air forms. At this time, it is preferable to supply at 0.1 to 1.0 ml / min to one side of the end portion, because mixing of foreign matters into the cast film can be prevented. In addition, it is preferable to use a pump with a pulsation rate of 5% or less as a pump for supplying this liquid.

  Below the casting die 73, there is provided a casting band 75 that spans the rotating rollers 68 and 74. The rotating rollers 68 and 74 are rotated by a driving device (not shown), and the casting band 75 travels endlessly with the rotation. The casting band 75 is preferably one that can move at a moving speed of 10 to 200 m / min. In order to set the surface temperature of the casting band 75 to a predetermined value, it is preferable that the heat transfer medium circulation device 84 is attached to the rotary rollers 68 and 74. The casting band 75 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 68 and 74 used in the present embodiment, and the heat transfer medium maintained at a predetermined temperature passes through the flow path. The temperatures of the rotary rollers 68 and 74 are maintained at a predetermined value.

  The width of the casting band 75 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 83, 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 75 is preferably made of stainless steel, and more preferably made of SUS21d6 so as to have sufficient corrosion resistance and strength. Moreover, it is preferable that the thickness unevenness of the entire casting band 75 is 0.5% or less.

It is also possible to use the rotating rollers 68 and 74 directly as a support. In this case, it is preferable that the rotation can be performed with high accuracy so that the rotation unevenness is 0.2 mm or less. In this case, it is preferable that the average roughness of the surfaces of the rotating rollers 68 and 74 is 0.01 μm or less. Therefore, the surface of the rotating rollers 68 and 74 is subjected to chrome plating or the like to give sufficient hardness and durability. In addition, it is necessary to suppress the surface defects of the support (the casting band 75 and the rotating rollers 68 and 74) to the minimum. Specifically, there is no pinhole of 30 μm or more, 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 preferably ² / m ² or less.

  The casting die 73, the casting band 75, etc. are accommodated in the casting chamber 85. The casting chamber 85 is provided with a temperature control equipment 86 for keeping the internal temperature at a predetermined value, and a condenser (condenser) 87 for condensing and recovering the volatile organic solvent. A recovery device 88 for recovering the condensed organic solvent is provided outside the casting chamber 85. Further, it is preferable that a decompression chamber 89 for controlling the pressure of the back surface of the casting bead formed from the casting die 73 to the casting band 75 is disposed, and this is also used in this embodiment. .

  Air blowing ports 90, 91, 92 are provided near the peripheral surface of the casting band 75 in order to evaporate the solvent in the casting film 93. Further, a wind shielding plate 94 is provided at the air blowing port 90 in the vicinity of the casting die 73 in order to suppress the surface variation of the casting film 93 due to the drying air being blown onto the casting film 93 immediately after casting. It is preferable.

  An online pressure gauge (hereinafter referred to as a pressure gauge) for measuring the pressure and temperature in the casting chamber 85 online and an online thermometer (hereinafter referred to as a thermometer) are provided. These pressure gauges and thermometers are connected to a controller (not shown). Then, the pressure value and temperature measured by the pressure gauge and thermometer are transmitted to the controller online. The pressure gauge and the thermometer are not particularly limited, and known ones can be used, but it is preferable that a differential pressure gauge is used as the pressure gauge and a thermocouple is used as the thermometer.

  The crossover part 100 is provided with a blower 101, and the ear clip device 76 downstream of the tenter device 10 is a crusher for finely cutting the waste at the side end (referred to as an ear) of the cut film 102. 103 is connected. The tenter device 10 is also provided with a pressure gauge and a thermometer, and the measured pressure value and temperature are transmitted to the controller online.

  The drying chamber 77 is provided with a number of rollers 104, and an adsorption recovery device 105 for adsorbing and recovering the solvent gas generated by evaporation is attached. In FIG. 5, the cooling chamber 78 is provided downstream of the drying chamber 77, but a humidity control chamber (not shown) may be provided between the drying chamber 77 and the cooling chamber 78. A forced static elimination device (static elimination bar) 106 for adjusting the charged voltage of the film 102 to a predetermined range (for example, −3 kV to +3 kV) is provided downstream of the cooling chamber 78. In FIG. 5, the forced static eliminating device 106 is illustrated on the downstream side of the cooling chamber 78, but is not limited to this installation position. Furthermore, in this embodiment, a knurling roller 107 for applying knurling to both edges of the film 102 by embossing is appropriately provided downstream of the forced static elimination device 106. The winding chamber 79 is provided with a winding roller 108 for winding the film 102 and a press roller 109 for controlling the tension during winding.

  Next, an example of a method for manufacturing the film 102 using the above-described film manufacturing line 70 will be described below. The dope 83 is always made uniform by the rotation of the stirrer 81. The dope 83 may be mixed with additives such as a plasticizer and an ultraviolet absorber even during the stirring.

After the dope 83 is sent to the filter device 72 by the pump 82 and filtered, the dope 83 is cast from the casting die 73 onto the casting band 75. The driving of the rotary rollers 68 and 74 is preferably adjusted so that the tension generated in the casting band 75 is 10 ⁴ to 10 ⁵ N / m. Further, the relative speed difference between the casting band 75 and the rotating rollers 68 and 74 is adjusted to be 0.01 m / min or less. It is preferable that the speed fluctuation of the casting band 75 is 0.5% or less, and the meandering in the width direction that occurs when the casting band 75 rotates once is 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 75 is provided, and feedback control is performed by a position controller (not shown) of the casting band 75 based on the measured value. More preferably, the position of the casting band 75 is adjusted. The casting band 75 immediately below the casting die 73 is preferably adjusted so that the positional fluctuation in the vertical direction accompanying the rotation of the rotary roller 74 is 200 μm or less. The temperature of the casting chamber 85 is preferably set to −10 to 57 ° C. by the temperature control equipment 86. The solvent evaporated inside the casting chamber 85 is recovered by the recovery device 88 and then regenerated and reused as a dope preparation solvent.

  A casting bead is formed from the casting die 73 to the casting band 75, and a casting film 93 is formed on the casting band 75. The temperature of the dope 83 during casting is preferably −10 to 57 ° C. 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 89. 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 89 and the temperature is controlled so that the internal temperature is kept at a predetermined temperature. The temperature of the decompression chamber 89 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 maintain the desired shape of the casting bead, it is preferable to attach a suction device (not shown) to the edge portion of the casting die 73. The edge suction air volume is preferably in the range of 1 L / min to 100 L / min.

  The casting film 93 moves as the casting band 75 travels. At this time, drying air is applied to the casting film 93 through the air blowing ports 90, 91, 92 to promote evaporation of the solvent. And although the surface shape of the cast film 93 may fluctuate by blowing of this dry wind, the wind-shielding board 94 has suppressed this fluctuation | variation. In addition, it is preferable that the surface temperature of the casting band 75 is −20 ° C. to 40 ° C. The pressure in the casting chamber 85 is measured with a pressure gauge. The pressure value is in the range of 0.09 MPa (absolute pressure) to 0.105 MPa. The temperature in the casting chamber 85 is measured with a thermometer. The temperature is in the range of 10 ° C to 50 ° C. In order to maintain these values, the controller controls the temperature control of the temperature control equipment 86, the air temperature from the air blowing ports 90, 91, 92, the air flow rate, and the like as appropriate.

  After the casting film 93 has a self-supporting property, it is peeled off from the casting band 75 while being supported by the peeling roller 110 as the wet film 16. The amount of residual solvent at the time of stripping is preferably 20% by mass to 250% by mass based on the solid content. Thereafter, the transfer unit 100 provided with a large number of rollers is conveyed, and the wet film 16 is fed into the tenter device 10. In the transition part 100, the drying of the wet film 16 is advanced by sending the drying air of desired temperature from the air blower 101. FIG. At this time, the temperature of the drying air is preferably 20 ° C to 250 ° C. In the transition section 100, it is also possible to apply a draw tension to the wet film 16 by making the rotation speed of the downstream roller faster than the rotation speed of the upstream roller.

  The tenter device 10 grips both ends of the wet film 16 with clips, and dries and stretches the wet film 16 in the width direction while conveying the wet film 16 in one direction (casting direction). Drying is performed by appropriately adjusting the drying conditions for each of a plurality of drying units 53 to 56 (see FIG. 1) obtained by dividing the inside of the tenter device 10 into a plurality of temperature zones. As described above, it is preferable that at least one direction of the wet film 16 in the casting direction and the width direction is stretched by 0.5% to 300% by the crossing portion 100 and / or the tenter device 10.

  After the wet film 16 is dried to a predetermined residual solvent amount by the tenter device 10, it is sent out downstream as a film 102. At this time, both edges of the both ends of the film 102 are cut by the edge-cutting device 76. The cut side end portion is sent to a crusher 103 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 it is possible to omit the step of cutting the both end portions of the film 102, it is preferable to carry out any of the steps from the casting step to the step of winding the film 102.

  The film 102 from which both end portions have been cut off is sent to the drying chamber 77 and further dried. Although the temperature in the drying chamber 77 is not specifically limited, It is preferable that it is the range of 50 to 160 degreeC. In the drying chamber 77, the film 102 is conveyed while being wound around a roller 104, and the solvent gas generated by evaporation is adsorbed and recovered by the adsorption recovery device 105. The air from which the solvent component has been removed is blown again as dry air inside the drying chamber 77. The drying chamber 77 is more preferably divided into a plurality of sections in order to change the drying temperature. In addition, when a preliminary drying chamber (not shown) is provided between the ear opener 76 and the drying chamber 77 to preliminarily dry the film 102, the temperature of the film 102 in the drying chamber 77 can be prevented from rapidly increasing. Therefore, the occurrence of the shape change of the film 102 can be further suppressed.

  The film 102 is cooled to approximately room temperature in the cooling chamber 78. A humidity control chamber (not shown) may be provided between the drying chamber 77 and the cooling chamber 78, and air adjusted to a desired humidity and temperature can be blown to the film 102 in the humidity control chamber. Is preferred. Thereby, it is possible to suppress the occurrence of curling of the film 102 and the occurrence of winding failure when winding.

  Moreover, the forced static elimination apparatus (static elimination bar) 106 sets the charged voltage while the film 102 is conveyed to a predetermined range (for example, −3 to +3 kV). In FIG. 5, the forced static elimination device 106 is provided on the downstream side of the cooling chamber 78, but the position is not limited thereto. Furthermore, it is preferable to provide a knurling roller 107 and to apply knurling to both edges of the film 102 by embossing. In addition, it is preferable that the unevenness | corrugation of the knurled location is 1-200 micrometers.

  Finally, the film 102 is taken up by the take-up roller 108 in the take-up chamber 79. At this time, it is preferable to wind the sheet while applying a desired tension with the press roller 109. More preferably, the tension is gradually changed from the start to the end of winding. The film 102 to be wound is preferably at least 100 m in the longitudinal direction (casting direction). Further, the width of the film 102 is preferably 600 mm or more, more preferably 1300 mm or more and 3000 mm or less, and further preferably 1500 mm or more and 2500 mm or less. The present invention is also effective when the film 102 having a width exceeding 3000 mm is formed. Note that the thickness of the completed film 102 is adjusted to be 15 μm or more and 100 μm or less.

  In the solution casting method of the present invention, when casting the dope 83, two or more types of dopes can be simultaneously co-casting or sequentially 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 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 83 is cast from the die slit to the support. In the case of simultaneous lamination and co-casting, it is preferable that the dope 83 in contact with the outside of the casting bead formed from the die slit to the support has a higher alcohol composition ratio than the inner dope 83.

  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 Up to this point, the details are described 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 [1073] to [1087] of JP-A-2005-104148, and these descriptions are also applied to the present invention. Can do.

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

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

  Further, it is preferable to use the cellulose acylate film as a base film as a functional material provided with another functional layer. 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.

The functional layer, at least one surfactant preferably contains ^{2 0.1mg / m 2 ~1000mg / m} , that at least one of a slip agent 0.1mg ^{/ m 2} ~1000mg ^/ m 2 containing Is preferred. Further, the functional layers, at least one matting agent preferably contains ^{2 0.1mg / m 2 ~1000mg / m} , to at least one sort of antistatic agents ^1mg / ^{m 2 ~1000mg} / m 2 containing Is preferred. In addition to the above, the method for applying a surface-treated functional layer for realizing various functions and properties on cellulose acylate film is described in paragraphs [0890] to [1072] of JP-A-2005-104148. Detailed conditions and methods are also described, and these descriptions can also 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 attached to a polarizer are attached 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 can be employed. Japanese Patent Application Laid-Open No. 2005-104148 (for example, paragraphs [1088] to [1265]) describes in detail TN type, STN type, VA type, OCB type, reflection type, and other examples of liquid crystal display devices. This method can also be applied to the present invention. In addition, in the same application, a description of a cellulose acylate film provided with an optically anisotropic layer, a cellulose acylate film provided with antireflection and antiglare functions, and biaxiality imparting appropriate optical performance. The use as a cellulose acylate film as an optical compensation film is also described. This can also be used as a polarizing plate protective film.

  Moreover, the cellulose triacetate film (TAC film) which is excellent in an optical characteristic by the manufacturing method of this invention can be obtained. The TAC film can be used as a polarizing plate protective film or a base film for a photographic photosensitive material, and can also be used as an optical compensation film for improving the viewing angle dependency of a liquid crystal display device for television. In particular, it is effective for applications that also serve as a protective film for a polarizing plate. Therefore, it is used not only in the conventional TN mode but also in 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.

It is the schematic of the tenter apparatus of this invention. It is sectional drawing which shows the conveyance guide part and return guide part which were provided in the casing of the tenter apparatus, and has shown the holding | grip start position which hold | grips a wet film. It is sectional drawing which shows the conveyance guide part and return guide part which were provided in the casing, and has shown the center position of the conveyance direction. It is a graph which shows the temperature in the width direction position of the wet film currently extending | stretching with a tenter apparatus, the code | symbol A has shown the temperature when using this embodiment, and the code | symbol B has shown the temperature when using a conventional apparatus, respectively. . It is the schematic of the film manufacturing line using this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Tenter apparatus 13, 14 Clip cooling mechanism 15 Casing 19 Conveyance path 20a, 21a Conveyance guide part 20c, 21c Return guide part 22 Left chain 23 Right chain 45 Clip 46 Grasp start position 47 Grasp release position 65 Cooling duct 70 Film production line

Claims (4)

While the film is transported along a transport path provided in the casing while gripping both sides of the film having a width of 1.3 m or more and 3.0 m or less with a plurality of clips provided on a pair of endless chains, the film surface In a tenter device that stretches in the width direction while drying the film by blowing dry air on the film surface by a blowing head arranged in parallel with
A pair of return guide portions that are provided outside the casing and guide the endless chain that is fed out of the casing until it is returned to the conveying path in the casing;
A pair of cooling ducts that are provided so as to cover a part or all of each of the return guide portions, and that cool the clip by the cooling air that is fed;
A tenter device comprising: Each of the endless chains includes a driving sprocket provided in the casing and downstream of the conveying direction in the conveying direction, a driven sprocket provided in the upstream side, and an upstream / downstream side of the casing and in the conveying direction. Is wound around at least four sprockets with two driven sprockets
2. The driven sprocket provided outside the casing and upstream of the transport direction is a tension sprocket that urges the endless chain in the film width direction. Tenter device. A dope containing a polymer and a solvent is cast from a casting die onto a support to form a cast film, and the cast film is formed as a wet film having a width of 1.3 m to 3.0 m from the support. While the film is transported along the transport path provided in the casing while being gripped by a plurality of clips provided on a pair of endless chains, the film surface is peeled off and sent to the tenter device. In the solution film-forming method of blowing the drying air on the film surface by a blowing head arranged in parallel with the film and stretching the wet film in the width direction while drying and winding the stretched film,
A chain returning step for returning an endless chain fed out of the casing into the casing by a pair of return guides provided outside the casing;
And a clip cooling step of cooling the clip by sending cooling air from a pair of cooling ducts provided so as to cover a part or all of each of the return guide portions.   4. The solution casting method according to claim 3, wherein the polymer is cellulose acylate.

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