JP4879061B2 - Solution casting equipment and method - Google Patents

Description

  The present invention relates to a solution casting apparatus and a method for conveying a web without dropping both side ends of the web before entering a tenter.

  Polymer films are widely used as optical functional films because they have excellent light transmission properties and flexibility and can be made into lightweight thin films. Among these, the cellulose ester film using cellulose acylate has toughness and low birefringence in addition to the above-described properties. This cellulose ester film is used as a protective film and an optical compensation film for polarizing plates, which are constituent members of liquid crystal display devices (LCDs) whose market has been expanding in recent years, including photographic photosensitive films.

  One method for producing a polymer film is a solution casting method. According to this solution casting method, a casting film is first formed by casting a dope containing a polymer and a solvent from a casting die onto a support. Then, after the cast film has a self-supporting property, the cast film is peeled off from the support as a wet film. Then, the wet film is dried with a tenter to reduce the residual solvent content. Thereby, a film is obtained. And after cutting the both ends of a film, it dries further with a drying apparatus. And the film which passed through the drying apparatus is wound up by the winding apparatus.

There are two types of tenter: pin tenter and clip tenter. The pin tenter includes an endless chain that circulates endlessly, a pin plate attached to the endless chain, and a plurality of pins attached on the pin plate. When the wet film enters the pin tenter, the pins are inserted into both end portions of the wet film. By inserting this pin, both end portions of the wet film are held. Further, the pin tenter is provided with an insertion brush for securely inserting the pin into both end portions of the wet film at a position where the insertion of the pin is started (see Patent Document 1).
JP 2003-103542 A

  However, although the wet film has a self-supporting property, it is extremely soft, so that both end portions thereof are easily detached from the wet film conveyance path. In particular, if both end portions of the wet film fall immediately before entering the pin tenter, the both end portions are not inserted into the pins of the pin tenter and the wet film may not be conveyed. In this case, the production line had to be stopped, and productivity was reduced.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a solution casting apparatus and method for transporting a web without dropping both side edges of a web when a very soft web such as a wet film enters a tenter.

The present invention conveys the web in a state in which a casting film containing a polymer and a solvent is peeled off from a casting support to obtain a web, and both end portions of the web are held on a tenter conveying path. And a transfer film forming facility that guides the web fed from the casting section on the transfer conveyance path to the tenter transfer path, wherein the tenter is below the tenter transfer path. A plurality of rotating drums lying on each other, an endless chain that is circulated around the rotating drum and rotated by rotation of the rotating drum, a pin plate that is attached to the endless chain, and both end portions in the width direction of the tenter conveyance path. A pin that is provided on the pin plate so as to be able to travel, and that is capable of penetrating both side ends of the web; And a downstream portion of the transfer conveyance path extends downward from the upstream side in the conveyance direction of the web toward the downstream side, and below the downstream end of the transfer conveyance path, A sag prevention means for preventing sag at both end portions of the web is provided, and a residual volatile content of the web in the transition part is 200% by mass or more and 300% by mass or less.

It is preferable that the sagging prevention means includes an air blowing portion that blows air against the both end portions. Moreover, it is preferable that the said fall prevention means is provided with the holding roller which hold | maintains the both-ends part of the said web.

The solution casting method of the present invention includes a film forming step of casting a dope containing a polymer and a solvent on a support to form a cast film, and the cast film has a self-supporting property. A film cooling process for cooling the cast film until the film cooling process, a stripping process for stripping the cast film after the film cooling process from the support to form a web, and a plurality of lying under the tenter transport path A rotating drum, an endless chain that is looped around the rotating drum and circulates by rotation of the rotating drum, a pin plate attached to the endless chain, and the pin plate that travels on both ends in the width direction of the tenter transport path Using a tenter having a pin that is capable of penetrating both side end portions of the web and an insertion portion that is disposed at an upstream end of the tenter transport path and penetrates both side end portions of the web through the pin. A tenter process for conveying the web in a state where both end portions of the web are held, and a transition process that is performed between the stripping process and the tenter process and guiding the web to the tenter, The downstream part of the web conveyance path in the crossing process extends downward from the upstream side of the web conveyance direction toward the downstream side, and uses a drop prevention means provided below the downstream end of the cross conveyance path. Thus, it is possible to prevent the both side end portions of the web from falling.

  According to the present invention, when a very soft web such as a wet film is transported, the both sides of the web are floated or held, so that the web can be transported without dropping the both ends of the web. Can do.

  A first embodiment of the present invention will be described. As shown in FIG. 1, the film production facility 10 includes a casting chamber 11, a crossing part 12, a pin tenter 13, a clip tenter 14, ear clip devices 15 a and 15 b, a drying device 16, and a cooling device 17. The winding device 18 is provided.

  In the casting chamber 11, a feed block 21 into which the dope from the dope production facility 20 is fed, a casting drum 22 as a support, a casting die 23 for casting the dope onto the casting drum 22, and casting. A stripping roller 26 for stripping the casting film 24 on the drum 22 as a wet film 25, a condenser 27 (condenser) for condensing and liquefying the solvent gas evaporated from the casting film 24 and the wet film 25, and a liquefied solvent. A recovery device 28 for recovery is provided. Further, a heat transfer medium supply device (not shown) is connected to the casting drum 22, and the surface temperature of the casting drum 22 is set to a desired value by supplying the heat transfer medium into the heat transfer medium supply device. The temperature is adjusted. Further, a temperature adjusting device 30 for adjusting the internal temperature is attached to the casting chamber 11.

  A dope channel is formed inside the feed block 21. By adjusting the arrangement of the flow paths, the casting film 24 having a desired structure can be formed. A decompression chamber 32 is attached to the casting die 23, and the decompression chamber 32 is used for a dope flow (hereinafter referred to as “bead”) from the discharge port of the casting die 23 to the casting drum 22. The back side is decompressed to stabilize the contact of the dope with the casting drum 22. A jacket (not shown) is attached to the decompression chamber 32, and the decompression chamber 32 is adjusted to a desired temperature.

  The casting drum 22 is composed of a stainless steel drum capable of continuous rotation. Further, the surface of the casting drum 22 is polished. As a result, a casting film 24 having excellent planarity is formed on the casting drum 22. A casting drum is used as the support, but the form of the support is not particularly limited. For example, a casting band wound around a pair of rollers and running endlessly may be used as the support. The support preferably has a width of about 1.1 to 2.0 times the casting width of the dope. The material of the support is preferably a material having corrosion resistance and high strength, such as stainless steel.

The shape, material, size and the like of the casting die 23 are not particularly limited, but it is preferable to use a coat hanger type because the casting width of the dope can be kept substantially uniform. Moreover, what has the discharge port about 1.1 to 2.0 times with respect to the casting width of dope is preferable. From the viewpoint of durability, heat resistance, etc., it is preferable to use precipitation hardening type stainless steel, and even if it is immersed in a mixed solution of dichloromethane, methanol and water for 3 months, it does not cause pores at the gas-liquid interface. Those having such corrosion resistance are preferred. Moreover, what has the corrosion resistance equivalent to the product made from SUS316 by the forced corrosion test in electrolyte aqueous solution can be used suitably. From the viewpoint of heat resistance, it is preferable to use one having a thermal expansion coefficient of 2 × 10 ⁻⁵ (° C. ⁻¹ ) or less.

Moreover, it is preferable that a cured film is formed at the tip of the discharge port of the casting die 23 for the purpose of improving wear resistance. The method for forming the cured film is not particularly limited, and examples thereof include ceramic coating, hard chrome plating, and nitriding treatment. When ceramics are used as the cured film, the cured film should be capable of grinding, have a high porosity, be superior in brittleness and corrosion resistance, and have a high degree of adhesion to the casting die. However, it is preferable to satisfy conditions such as low adhesion to the dope. Specific examples include tungsten carbide (WC), Al ₂ O ₃ , TiN, Cr ₂ O _{3 and the} like. Among these, WC is preferably used. The WC coating can be performed by a known thermal spraying method.

  In order to form the casting film 24 having excellent flatness, the dope contact surface of the casting die 23 is preferably smoothed by polishing or the like. Moreover, it is preferable to attach a suction device (not shown) to the edge portion of the casting die 23 and perform suction while setting the edge suction air volume to 1 to 100 L / min. Thereby, the flow of the wind which becomes a cause which forms an unevenness | corrugation on the surface of a bead can be reduced.

  A number of rollers 35 are installed in the crossover section 12. These rollers 35 convey the wet film 25 peeled off from the casting drum 22 to the pin tenter 13. Hereinafter, the transport direction of the wet film 25 is defined as the X direction. Further, a blower 40 is provided above the conveyance path of the wet film 25, and the blower 40 blows dry air on the wet film 25 to promote drying of the wet film 25.

  As shown in FIGS. 2 and 3, the pin tenter 13 is spanned between rotating drums 40 and 41 that are driven to rotate, the rotating drums 40 and 41, and the other rotating drum (not shown). Endless chains 42 and 43 that circulate according to rotation, a pin plate 45 attached to the endless chains 42 and 43, a number of pins 46 attached on the pin plate, and the pins 46 on both sides of the wet film 25. Pin insertion portions 47 and 48 to be inserted into end portions (hereinafter referred to as “ear portions”) 25a are provided. In addition, in order to avoid that a figure becomes complicated, the code | symbol 45 is attached | subjected to only one of several pin plates. The same applies to the pin 46.

  As shown in FIG. 3, the pin insertion portion 47 is provided above the rotary drum 40, and includes an insertion brush 50 and a cover 51 that houses the insertion brush 50. The insertion brush 50 includes a rotating shaft 50a and a brush 50b attached around the rotating shaft 50a. The rotary shaft 50a is rotatably attached to the cover 51 so that the brush 50b and the pin plate 45 are in contact with each other. Therefore, when the pin 46 approaches the contact position between the brush 50b and the pin plate 45, the pin 46 enters the brush 50b. The insertion brush 50 rotates in the counterclockwise direction (“R direction” in FIG. 3) according to the movement of the pin 46 that has entered the brush 50b. Since the other pin insertion portion 48 is the same as the pin insertion portion 47, the description thereof is omitted.

  When the wet film 25 enters the pin tenter 13, the ear 25 a is inserted into the tip of the pin 46. Then, the ear portion 25 a is inserted into the root portion of the pin 46 by the insertion brush 50. Thereby, the ear | edge part 25a is reliably hold | maintained by the pin 46. FIG.

  As shown in FIGS. 2 and 4, drop prevention devices 55 and 56 for preventing the drop of the ear part 25 a are provided below the ear part 25 a and immediately before the ear part 25 a is inserted into the pin 46. ing. The sagging prevention device 55 includes a case 57, an air supply device 59, and a holding roller 60. Note that the other drop prevention device 56 is the same as the drop prevention device 55, and a description thereof will be omitted.

  A predetermined number of air blowing holes 61 a are formed in the upper surface 61 of the case 57. An air intake hole 62 a is formed in the lower surface 62 of the case 57. The air supplier 59 supplies the air 63 into the case 57 through the air intake hole 62a. The air 63 supplied into the case 57 is blown to the ear portion 25a through the air blowing hole 61a. Thereby, the ear | edge part 25a floats. Here, in FIG. 4, only one of the plurality of air blowing holes is denoted by reference numeral 61 a in order to avoid the drawing from becoming complicated. The same applies to the air 63.

  The air blowing holes need not be limited to the round holes shown in FIG. For example, it may be a rectangular hole. Further, a nozzle for air blowing may be provided in place of the air blowing hole.

  The holding roller 60 includes a roller main body 64 and rotating shafts 65 attached to both ends of the roller main body 64. An opening 61b is formed in the upper surface 61 of the case, and the rotation shaft 65 is rotatably attached to the case 57 so that a substantially upper half of the roller body 64 is exposed from the opening 61b. The roller body 64 contacts the ear portion 25a and holds the ear portion 25a from below. Note that the holding roller 60 may be provided with a Teflon (registered trademark) coat or the like for preventing the film such as the wet film 25a from sticking. When smoothness is required, the holding roller 60 is subjected to the same processing as that performed on the surface of the casting drum 22.

  As described above, the ear portion 25a is made to reach the insertion start position of the pin 46 by floating or holding the ear portion 25a of the wet film immediately before entering the pin tenter 13 using the sagging prevention devices 55 and 56. be able to. Thereby, the conveyance of the wet film 25 can be performed stably. Here, it is preferable that the residual volatile content of the wet film 25 until it is peeled off from the casting drum 22 and enters the pin tenter 13 is 200% by mass or more and 300% by mass or less.

  As shown in FIG. 1, the clip tenter 14 is provided downstream of the pin tenter 13, grips and conveys the ear portion 25 a of the wet film coming out of the pin tenter 13, and performs drying. Thereby, the film 37 is obtained. The edge-cutting device 15 a cuts both side ends of the wet film 25 that has come out of the pin tenter 13. Further, the ear clip device 15b cuts both end portions of the film 37 that has come out of the clip tenter 14. A crusher 66 is connected to the ear-cutting devices 15a and 15b, and both end portions of the wet film 25 and the film 37 are crushed by the crusher 66 into chips. Then, the film 37 that has passed through the ear-cutting device 15 b is sent to the drying device 16. A large number of rollers 67 are provided inside the drying device 16, and the film 37 is dried while being conveyed by the rollers 67. The solvent gas generated from the film 37 in the drying device 16 is adsorbed and recovered by an adsorption recovery device 69 provided outside the drying device 16. The film 37 exiting the drying device 16 is sent to the cooling device 17 where it is cooled to approximately room temperature.

  The winding device 18 includes a winding roller 70, and the film 37 that has exited the cooling device 17 is wound into a roll by the winding roller 70. Further, the winding device 18 includes a press roller 71, and the press roller 71 controls the tension of the film 37 wound around the winding roller 70.

  Through the above steps, the film 37 having excellent flatness is manufactured stably at high speed. The width of the film 37 manufactured in the above embodiment is preferably 1400 mm or more and 2500 mm or less. In addition, even if it is a case where the width | variety of the film 37 exceeds 2500 mm, the effect of this invention can be acquired. Further, the thickness of the film 37 produced in the above embodiment is preferably 20 μm or more and 100 μm or less, more preferably 20 μm or more and 80 μm or less, and most preferably 30 μm or more and 80 μm or less.

  In addition, although the sagging prevention apparatus of this invention was introduce | transduced into the film manufacturing equipment, not only this but the sagging prevention apparatus of this invention can be introduced also into the web manufacturing equipment which manufactures a web.

  In the above embodiment, the case where a single-layer film is manufactured using one kind of dope has been described. However, the present invention is also effective when a cast film having a multilayer structure is formed. In this case, a known method such as casting a desired number of dopes simultaneously or sequentially may be used, and there is no particular limitation. Also, from the structure of casting die, decompression chamber, support, etc., co-casting, peeling method, stretching, drying conditions of each step, handling method, curling, winding method after flatness correction, solvent recovery method, film The collection method is described in detail in paragraphs [0617] to [0889] of JP-A-2005-104148, and the inventions according to these descriptions can also be applied to the present invention. In addition, the performance of the completed film, the degree of curling, the thickness, and the measurement methods thereof are described in paragraphs [1073] to [1087] of JP-A-2005-104148. The invention can also be applied to the present invention.

  It is preferable to perform a surface treatment on at least one surface of the completed film because the degree of adhesion with an optical member such as a polarizing plate can be increased. Examples of the surface treatment include vacuum glow discharge treatment, atmospheric pressure plasma discharge treatment, ultraviolet irradiation treatment, corona discharge treatment, flame treatment, acid treatment, alkali treatment, etc., and at least one of these treatments is performed. Is preferred.

  When a completed film is used as a base and a desired functional layer is provided on both sides or one side thereof, it can be used as various functional films. Examples of the functional layer include an antistatic layer, a cured resin layer, an antireflection layer, an easy adhesion layer, an antiglare layer, and an optical compensation layer. For example, when an antireflection layer is provided, an antireflection film capable of providing high image quality by preventing reflection of light can be obtained. The functional layer and the forming method are described in detail in paragraphs [0890] to [1072] of JP-A-2005-104148, and the inventions related to these descriptions can also be applied to the present invention. it can. Regarding specific uses of the polymer film, for example, TN type, STN type, VA type, OCB type, reflective type and the like described in paragraphs [1088] to [1265] of JP-A-2005-104148, etc. For use in liquid crystal display devices.

  Next, the raw material of dope manufactured with the dope manufacturing equipment 20 is shown below.

  It is preferable to use cellulose ester as a dope raw material because a highly transparent film can be obtained. Examples of the cellulose ester include lower fatty acid esters of cellulose such as cellulose triacetate, cellulose acetate propionate, and cellulose acylate butyrate. Especially, it is preferable to use a cellulose acylate from the height of transparency, and it is preferable to use a triacetyl cellulose (TAC). The dope used in the above embodiment includes triacetyl cellulose (TAC) as a polymer. Thus, when using TAC, it is preferable that 90 mass% or more of TAC is a particle | grain of 0.1-4 mm.

As said cellulose acylate, in order to obtain a film with higher transparency, it is preferable that the substitution degree of the acyl group to the hydroxyl group of cellulose satisfies all of the following formulas (a) to (c). A and B in the following formula represent the substitution degree of the acyl group with respect to the hydrogen atom in the hydroxyl group of cellulose. Specifically, A is the substitution degree of the acetyl group, and B has 3 to 22 carbon atoms. The degree of substitution of the acyl group.
(A) 2.5 ≦ A + B ≦ 3.0
(B) 0 ≦ A ≦ 3.0
(C) 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 (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 of the esterification of the hydroxyl group of cellulose for each of the 2-position, 3-position and 6-position. The degree of substitution 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 with an acyl group, and DS3 is a ratio in which the hydrogen of the hydroxyl group at the 3-position in the glucose unit is substituted with an acyl group. DS6 is the ratio in which the hydrogen of the 6-position hydroxyl group is replaced by an acyl group in the glucose unit.

  Only one kind of acyl group may be used for cellulose acylate, or two or more kinds 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 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. Furthermore, 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. When such cellulose acylate is used, a dope having excellent solubility can be prepared. In the case of using the cellulose acylate as described above, if a non-chlorine solvent is used, a dope having very excellent solubility, low viscosity, and excellent filterability can be prepared. .

  Cellulose, which is a raw material for cellulose acylate, may be obtained from either linter cotton or pulp cotton, but is preferably obtained from linter cotton.

  The acyl group having 2 or more carbon atoms of cellulose acylate may be an aliphatic group or an aryl group, and is not particularly limited. For example, cellulose alkylcarbonyl ester, alkenylcarbonyl ester, aromatic carbonyl ester, aromatic alkylcarbonyl ester and the like can be mentioned. Further, each may 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. .

  The details of cellulose acylate that can be used in the present invention are described in paragraphs [0140] to [0195] of JP-A-2005-104148, and these descriptions also apply to the present invention. Can do.

  The solvent used as the dope raw material is preferably an organic compound that can dissolve the polymer used. However, in the present invention, the dope means a mixture obtained by dissolving or dispersing the polymer in the solvent, and therefore a solvent having low solubility with the polymer can also be used. Examples of the solvent that can be suitably used include aromatic hydrocarbons such as benzene and toluene, halogenated hydrocarbons such as dichloromethane, chloroform, and chlorobenzene, and alcohols such as methanol, ethanol, n-propanol, n-butanol, and diethylene glycol. , Ketones such as acetone and methyl ethyl ketone, esters such as methyl acetate, ethyl acetate and propyl acetate, ethers such as tetrahydrofuran and methyl cellosolve, and the like. Two or more kinds of solvents may be selected from these solvents and mixed solvents may be used. Among these, use of dichloromethane is preferable because a dope having excellent solubility can be obtained and the solvent in the cast film can be volatilized in a short time to form a film.

  As said halogenated hydrocarbon, a C1-C7 thing is used preferably. Furthermore, from the viewpoints of compatibility with the polymer, peelability which is an index of ease of peeling of the cast film peeled off from the support, mechanical strength of the film, optical properties, etc., dichloromethane has 1 to 5 carbon atoms. It is preferable to use one of these alcohols or a mixture of several alcohols. The content of alcohol is preferably 2 to 25% by weight, more preferably 5 to 20% by weight, based on the entire solvent. Specific examples of the alcohol include methanol, ethanol, n-propanol, isopropanol, n-butanol, etc. Among them, it is preferable to use methanol, ethanol, n-butanol, or a mixture thereof.

  Recently, a solvent composition not using dichloromethane has been proposed in order to minimize the influence on the environment. For this purpose, ethers having 4 to 12 carbon atoms, ketones having 3 to 12 carbon atoms, and esters having 3 to 12 carbon atoms are preferable, and these are preferably used by being mixed appropriately. These compounds may have a cyclic structure, and compounds having two or more functional groups of ether, ketone and ester, that is, any of -O-, -CO-, and -COO- are also used as a solvent. Can be used. In addition, the solvent may have another functional group such as an alcoholic hydroxyl group. In addition, when it has two or more types of functional groups, the carbon number should just be in the prescription | regulation range of the compound which has either functional group, and it does not specifically limit.

  Depending on the purpose, the dope may be added with various known additives such as a plasticizer, an ultraviolet absorber (UV agent), a deterioration preventing agent, a slipping agent, and a peeling accelerator. For example, as the plasticizer, phosphate plasticizers such as triphenyl phosphate and biphenyldiphenyl phosphate, phthalate plasticizers such as diethyl phthalate, and various known plasticizers such as polyester polyurethane elastomers are used. be able to.

  Moreover, it is preferable to add fine particles to the dope for the purpose of preventing adhesion between films or adjusting the refractive index. As the fine particles, a silicon dioxide derivative is preferably used. The silicon dioxide derivative in the present invention includes silicon dioxide and a silicone resin having a three-dimensional network structure. As such a silicon dioxide derivative, it is preferable to use an alkylated surface. Fine particles that have been subjected to a hydrophobic treatment such as an alkylation treatment have excellent dispersibility in a solvent, so that a dope can be prepared without agglomeration of the fine particles, and a film can be produced. It is possible to produce a film with few state defects and high transparency.

  As described above, as the fine particles whose surface is alkylated, for example, Aerosil R805 (manufactured by Nippon Aerosil Co., Ltd.) which is commercially available as a silicon dioxide derivative having an octyl group introduced on its surface can be used. . In order to obtain a highly transparent film while ensuring the effect of adding fine particles, the fine particle content relative to the solid content of the dope is preferably 0.2% or less. Further, the average particle diameter is preferably 1.0 μm or less, more preferably 0.3 to 1.0 μm, and particularly preferably 0.4 to 0 so that the fine particles do not hinder the passage of light. .8 μm.

  As described above, in the present invention, it is preferable to prepare a dope using TAC as a polymer in order to obtain a highly transparent polymer film. In this case, it is preferable that the ratio of containing TAC is 5 to 40% by weight with respect to the total amount of the dope after mixing the solvent, additives and the like. More preferably, the ratio containing TAC is 15 to 30% by weight, and particularly preferably 17 to 25% by weight. Moreover, it is preferable to make the ratio which contains an additive (mainly a plasticizer) into 1 to 20 weight% with respect to the whole solid content including the polymer, other additives, etc. which are contained in dope.

  Note that various additives such as solvents, plasticizers, ultraviolet absorbers, deterioration inhibitors, slipping agents, release accelerators, optical anisotropy control agents, retardation control agents, dyes, release agents, and the like, and fine particles are disclosed in JP-A-2005. No. 104148, paragraphs [0196] to [0516] describe in detail, and these descriptions can also be applied to the present invention. Further, it is a method for producing a dope using TAC. For example, materials, raw materials, additive dissolution methods and addition methods, filtration methods, defoaming, and the like are also disclosed in JP-A-2005-104148 [0517]. It is described in detail from paragraph to [0616] paragraph, and these descriptions can also be applied to the present invention.

  A film 37 was manufactured in the film manufacturing facility 10 shown in FIG. An appropriate amount of the dope was sent from the dope production facility 20 to the casting die 23 via the feed block 21, and the dope was cast from the casting die 23 onto the continuously rotating drum 22 to form a casting film 24. . The discharge port of the casting die 23 was a slit having a width of 1.8 m. The temperature of the dope at the time of casting was set to 36 ° C. The internal temperature of the feed block 21 was 36 ° C. The pressure behind the bead was reduced to 600 Pa and the pressure behind the bead was reduced.

  As the casting drum 22, a stainless steel drum capable of controlling the number of rotations was used. The surface temperature of the casting drum 22 was set to −10 ° C. by supplying the refrigerant from the heat transfer medium supply device into the casting drum 22. The temperature inside the casting chamber 11 was always 35 ° C. using the temperature control device 30.

  When the casting film 24 was cooled and gelled and became self-supporting, the casting film 24 was peeled off as a wet film 25 by the peeling roller 26. The peeled wet film 25 was sent to the crossover section 12 and conveyed while being supported by a plurality of rollers 35 provided in the crossover section 12. During the conveyance, the air 37 adjusted to 40 ° C. was supplied from the blower 40 to dry the film 37.

  As shown in FIG. 2 to FIG. 4, sagging prevention devices 55 and 56 are provided below the wet film ear 25a and just before the pin 46 is inserted into the ear 25a. Air was blown to the ear portion 25a from the air blowing holes of the sagging prevention devices 55 and 56, and the ear portion 25a was lifted. Further, the ears were held by the holding rollers of the sagging prevention devices 55 and 56. The wet film ear 25a was securely inserted into the pin 43 by the pin insertion portions 48 and 49 of the pin tenter 13.

As shown in FIG. 1, the wet film 25 that passed through the pin tenter 13 was sent to the clip tenter 14. The clip tenter 14 was transported while gripping the ears 25a of the wet film 25, and the wet film 25 was dried during the transport. As a result, a film 37 was obtained. Both end portions of the wet film 25 and the film 37 were cut using the ear-cutting devices 15a and 15b. Both ends of the cut wet film 25 and the film 37 were sent to a crusher 66 through a cutter blower (not shown) and crushed into chips having an average of about 80 mm ² .

  A pre-drying chamber (not shown) was provided between the ear opener 15b and the drying device 16, and the film 37 was preheated by supplying drying air at 100 ° C. and then sent to the drying device 16. In the drying device 16, the film 37 is conveyed while being wound around a plurality of rollers 67, and drying is performed during the conveyance. The internal temperature of the drying device 16 was adjusted so that the film surface temperature of the film 37 was 140 ° C. The drying time of the film 37 in the drying device 16 was 10 minutes. The film surface temperature of the film 37 was measured using a thermometer (not shown) provided immediately above the conveyance path of the film 37 and in the vicinity of the surface. In the drying device 16, after recovering the solvent gas volatilized from the film 37 using an adsorption recovery device 69 having an adsorbent composed of activated carbon and a desorbent composed of dry nitrogen, the water content is reduced to 0.3 wt% or less. The water in the solvent gas was removed until

  A humidity control chamber (not shown) is provided between the drying device 16 and the cooling device 17, and air having a temperature of 50 ° C. and a dew point of 20 ° C. is supplied to the film 37. % Air was blown to adjust the humidity, and the curl generated in the film 37 was corrected. Next, the film 37 was sent to the cooling device 17, and the film 37 was gradually cooled until it became 30 degrees C or less.

  The film 37 was sent to the winding device 18, and was wound by a winding roller 70 having a diameter of 169 mm while applying a pressing force of 50 N / m to the film 37 by the press roller 71. At the time of winding, the tension at the start of winding of the film 37 was 300 N / m, and the tension at the end of winding was 200 N / m. Thus, a roll-shaped film 37 was obtained.

  The completed film 37 had a width of 1700 mm and a film thickness of 80 μm. In addition, the average drying rate of the cast film and the film was set to 20% by weight / min throughout the film forming process.

The dope raw materials used in this example are shown below.
Cellulose triacetate 100 parts by weight Dichloromethane 320 parts by weight Methanol 83 parts by weight 1-butanol 3 parts by weight Plasticizer A 7.6 parts by weight Plasticizer B 3.8 parts by weight UV agent a 0.7 part by weight UV agent b 0.3 part by weight Part citrate ester mixture 0.006 parts by weight fine particles 0.05 parts by weight

  The cellulose triacetate has a substitution degree of 2.84, a viscosity average polymerization degree of 306, a water content of 0.2% by weight, a viscosity of 6% by weight in a dichloromethane solution of 315 mPa · s, an average particle diameter of 1.5 mm, and a standard deviation of 0.8. 5 mm powder, plasticizer A is triphenyl phosphate, plasticizer B is diphenyl phosphate, and UV agent a is 2 (2′-hydroxy-3 ′, 5′-di- tert-butylphenyl) benzotriazole, UV agent b is 2 (2′-hydroxy-3 ′, 5′-di-tert-amylphenyl) -5-chlorobenzotriazole, and the citrate ester compound is It is a mixture of acid, monoethyl ester, diethyl ester and triethyl ester, and the fine particles have a mean particle size of 15 nm and a Mohs hardness of about 7 It is silicon. In addition, when the dope is prepared, a retardation control agent (N—N-di-m-toluyl-N—P-methoxyphenyl-1,3,5-triazine-2,4,6-triamine) is used as a film. It added so that it might become 4.0 weight% with respect to the total weight.

  In the above embodiment, the ears 25a can be reliably reached at the insertion start position of the pin 46 by floating and holding the ears 25a of the wet film 25 by the sagging prevention devices 55 and 56. Thereby, the wet film 25 was able to be conveyed stably.

It is the schematic of a film manufacturing equipment. It is a top view which shows the fall prevention apparatus of this invention, and its periphery. It is a front view which shows the fall prevention apparatus of this invention, and its periphery. It is sectional drawing of the sagging prevention apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Film manufacturing equipment 13 Pin tenter 22 Casting drum 55,56 Drop prevention device 60 Holding roller 61a Air blowing hole 63 Air

Claims (4)

A casting part that peels off a casting film containing a polymer and a solvent from a casting support, and obtains a web; and a tenter that transports the web while holding both side ends of the web on a tenter transporting path; In the solution film-forming facility provided with a transition part that guides the web sent out from the casting part on the transition transport path to the tenter transport path,
The tenter is
A plurality of rotating drums lying below the tenter transport path;
An endless chain that wraps around the rotating drum and circulates by rotation of the rotating drum;
A pin plate attached to the endless chain;
Pins that are provided on the pin plate so as to travel on both side ends in the width direction of the tenter transport path, and that can penetrate both side ends of the web;
An insertion portion that is arranged at the upstream end of the tenter conveyance path and that penetrates both side ends of the web through the pin;
The downstream portion of the transfer conveyance path extends downward from the upstream side in the conveyance direction of the web toward the downstream side,
Below the downstream end of the transfer conveyance path, a drop prevention means for preventing the side edges of the web from dropping is provided,
The solution casting apparatus, wherein the web has a residual volatile content of 200% by mass or more and 300% by mass or less at the transition part. The solution casting apparatus according to claim 1 , wherein the sagging prevention means includes an air blowing portion that blows air toward the both end portions . The solution casting apparatus according to claim 1 , wherein the sagging prevention means includes a holding roller that holds both end portions of the web . A film forming step of casting a dope containing a polymer and a solvent on a support to form a cast film;
A film cooling step for cooling the cast film until the cast film is self-supporting;
A stripping step of stripping the cast film after the film cooling step from the support to form a web;
A plurality of rotating drums lying below the tenter conveying path, an endless chain that is looped around the rotating drum and circulates by the rotation of the rotating drum, a pin plate attached to the endless chain, and a width direction of the tenter conveying path A pin that is provided on the pin plate so as to run on both side edges and that can penetrate both side edges of the web; and a difference that is disposed at the upstream end of the tenter transport path and that penetrates both sides of the web through the pins. A tenter process for transporting the web in a state where both end portions of the web are held, using a tenter having a recessed portion,
A transition step that is performed between the stripping step and the tenter step and guides the web to the tenter;
The downstream part of the web conveyance path in the crossing step extends downward from the upstream side in the web conveyance direction toward the downstream side,
A solution casting method characterized by using a drop prevention means provided below a downstream end of the transfer conveyance path to prevent a drop at both end portions of the web.

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