JPH1177718A - Apparatus and method for drying cellulose triacetate film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the generation of elongation, deformation and wrinkles during tenter feed by specifying the blow-off angle from a blow-off port until the amt. of the solvent remaining in the web peeled from a support becomes a specific value, and specifying the difference between the upper and lower limit values of the wind velocity distribution on the surface of a film to blow off the drying gas. SOLUTION: A dope film (web) 1 of a cellulose acetate soln. (dope) peeled at a peel point 4 is introduced into a drying zone 9 while the dope cast on a support 3 from a die 2 is dried and fed by a tenter to be dried by the drying gas blown off from dryers 10 provided above and below the web 1. At this time, the blow-off angle of the drying gas from a blow-off port 14 is set to 30-150 deg. with respect to the plane of a film until the residual amt. of the solvent in the web 1 peeled from the support 3 becomes 4 wt.% and, when the wind velocity distribution on the surface positioned in the blow-off entending direction of the drying gas is set on the basis of the upper limit value of wind velocity, the difference between upper and lower limit values is set within a range of 20% or less of the upper limit value to blow off the drying gas to perform drying.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cellulose triacetate for high productivity while maintaining good flatness of a cellulose triacetate film used for a silver halide photographic material or a support of a liquid crystal image display device. The present invention relates to an apparatus and a method for drying a film. The present invention relates to a novel drying apparatus and a novel drying method for performing drying in a conventional tenter more efficiently and while taking into consideration the quality of a cellulose triacetate film such as flatness.

[0002]

2. Description of the Related Art An apparatus and a method for producing a cellulose triacetate film by a solution casting method for a cellulose triacetate film are shown in FIG.
Is cast from a die 2 onto an endlessly running support (for example, a belt or a drum) 3 having a mirror-finished surface, and the doped film is peeled off at a peeling point 4 (also referred to as a web). During this time, the web is dried by the introduced dry gas air 7 and wound up by a winder 8 as a cellulose triacetate film. For drying, a method of drying with infrared rays or the like has been used (for example, US Pat. No. 2,319,053). A method has also been developed in which the web is moved in a non-contact state with the suspended body by blowing the air and floating the web with the pressure instead of directly hanging the roll on a roll (for example, Japanese Patent Application Laid-Open No. 55-135046). ).

On the other hand, as a stretching method used to improve the mechanical strength of a film such as polyester or polypropylene, there is a tenter method in which both side edges of the film are fixed with clips or the like and stretched 2 to 6 times. A technology for manufacturing a substrate of a liquid crystal display panel from a film of a phenoxy resin or the like utilizing this tenter method has also been developed (Japanese Patent Application Laid-Open No. 59-211006), and it is known that a cellulose acetate film can be used for this film. It is suggested in some.

[0004]

The slowness of film formation by the solution casting method is a major problem because of the slow speed. In recent years, the film is transported by a tenter instead of a group of rolls and dried to increase the drying speed. (See, for example, JP-A-62-115035 or 62-46).
626). It is described that the use of a tenter improves the flatness of the cellulose triacetate film.However, in order to improve the flatness by this method, a long tenter must be installed. A bulky and inexpensive cellulose triacetate film cannot be provided. Generally, efficient drying is generally performed by strongly applying a drying wind to the web. However, in this case, loosening, wrinkling, partial deformation, and blowing unevenness are caused. Although the drying was efficient due to the appearance of streaks like that, no satisfactory product was obtained in terms of quality. Further, when the width of the web is increased in order to make the productivity more efficient, the above-mentioned defects become more remarkable.

Therefore, development of a more efficient drying apparatus or drying method has been desired.

An object of the present invention is to prepare a cellulose triacetate film by a solution casting method, and to reduce a residual solvent as much as possible to a level that hardly causes elongation, deformation, wrinkles, etc. even when dried during transport of a tenter. It is an object of the present invention to provide an efficient drying apparatus and method.

[0007]

Accordingly, the present inventor has developed a drying apparatus and a drying method capable of producing a wider cellulose triacetate film.

The above objects of the present invention can be achieved by the following (1) to (1)
The problem was solved by the embodiment of 6).

(1) A portion for casting a cellulose triacetate solution on a support running endlessly, drying the web by peeling the web from the support, and passing a dry gas while transporting the web by a tenter. In forming a cellulose triacetate film by a solution casting method in which a dry gas is blown toward a web from a blowout dryer having blowout ports located above and below the web conveyed in the tenter and dried, the web is supported. After peeling off from the film, until the residual solvent amount in the web becomes 4% by weight, the angle of blowing from the blowing port is in the range of 30 ° to 150 ° with respect to the film plane, and the blowing of dry gas is extended. When the wind speed distribution on the film surface located in the direction is based on the upper limit of the wind speed, the difference between the upper limit and the lower limit is the upper limit And within 20% drying apparatus cellulose triacetate film characterized by drying the web blows dry gas.

(2) A portion for casting a cellulose triacetate solution on an endlessly running support, drying the web by peeling the web from the support, and passing a drying gas through the web while transporting the web by a tenter. In forming a cellulose triacetate film by a solution casting method in which a dry gas is blown toward a web from a blowout dryer having blowout ports located above and below the web conveyed in the tenter and dried, the web is supported. After peeling off from the film, until the residual solvent amount in the web becomes 4% by weight, the angle of blowing from the blowing port is in the range of 30 ° to 150 ° with respect to the film plane, and the blowing of dry gas is extended. When the wind speed distribution on the film surface located in the direction is based on the upper limit of the wind speed, the difference between the upper limit and the lower limit is defined as the upper limit. It is within 0%, the drying gas blowing, drying a cellulose triacetate film, characterized by drying.

(3) In forming a cellulose triacetate film by the solution casting method, when the amount of the residual solvent in the web is 130% by weight or more and 70% by weight or more, the dry gas Wind speed on the web surface is 0.5m / sec or more and 20m / sec
Below, when the amount of the residual solvent is less than 70% by weight and 4% by weight or more, the wind speed of the dry gas is 0.5 m / sec or more and 40m /
A method for drying a cellulose triacetate film, characterized by drying by a dry gas wind blown out in seconds or less.

(4) In forming a cellulose triacetate film by the solution casting method, when the amount of the residual solvent in the web is 130% by weight or more and 70% by weight or more, the wind speed of the dry gas on the web surface is 0.1%. When the amount of the residual solvent is less than 70% by weight and 4% by weight or more, the wind speed of the dry gas is 0.5 m / sec.
(2) The method for drying a cellulose triacetate film according to (2), wherein the drying is performed by a dry gas wind blown at a speed of c to 40 m / sec.

(5) In forming the cellulose triacetate film by the solution casting method, when the temperature distribution of the dry gas in the width direction of the web is based on the upper limit value of the gas temperature, the upper limit value and the lower limit value are determined. A method for drying a cellulose triacetate film, wherein the difference is within 10% of the upper limit.

(6) In forming the cellulose triacetate film by the solution casting method, when the temperature distribution of the dry gas in the width direction of the web is based on the upper limit of the gas temperature, the upper limit and the lower limit are determined. The method for drying a cellulose triacetate film according to any one of (2) to (4), wherein the difference is within 10% of the upper limit.

(7) In forming a cellulose triacetate film by the solution casting method, when the amount of the residual solvent in the web is 4% by weight or more and 200% by weight or less, a blow mold positioned above and below the conveyed web. A method for drying a cellulose triacetate film, wherein the air flow ratio q (q = air flow on the upper surface of the web / air flow on the lower surface of the web) of the drying gas blown from the outlet of the dryer is 0.2 ≦ q ≦ 1.

(8) In forming a cellulose triacetate film by the above-mentioned solution casting method, when the amount of residual solvent in the web is 4% by weight or more and 200% by weight or less, a blow mold positioned above and below the conveyed web. Any of (2) to (6), wherein an air volume ratio q (q = air volume on the upper surface of the web / air volume on the lower surface of the web) of the drying gas blown out from the outlet of the dryer is 0.2 ≦ q ≦ 1. A method for drying a cellulose triacetate film according to any one of the above.

(9) In forming a cellulose triacetate film by the solution casting method, at least one kind of gas is used as a dry gas, and its average specific heat is 31.
A method for drying a cellulose triacetate film, which is from 0 J / K · mol to 250 J / K · mol.

(10) In forming a cellulose triacetate film by the solution casting method, at least one kind of gas is used as a drying gas, and its average specific heat is 3%.
The method for drying a cellulose triacetate film according to any one of (2) to (8), which is 1.0 J / K · mol or more and 250 J / K · mol or less.

(11) In forming a cellulose triacetate film by the solution casting method, the concentration of the organic compound that is liquid at room temperature and contained in the drying gas during drying is as follows:
A method for drying a cellulose triacetate film, characterized by drying with a dry gas having a saturated vapor pressure of 50% or less.

(12) In forming the cellulose triacetate film by the solution casting method, the concentration of the organic compound that is liquid at room temperature and contained in the drying gas during drying is as follows:
The method for drying a cellulose triacetate film according to any one of (2) to (10), wherein the drying is performed with a dry gas having a saturated vapor pressure of 50% or less.

(13) In forming the cellulose triacetate film by the solution casting method, the organic solvent of the exhaust gas of the dry gas after web drying is recovered in whole or in part, and is reused as the dry gas. A method for drying a cellulose triacetate film.

(14) In forming the cellulose triacetate film by the solution casting method, the organic solvent of the exhaust gas of the drying gas after web drying is recovered in whole or in part, and is reused as the drying gas. The method for drying a cellulose triacetate film according to any one of (2) to (12).

(15) A method for drying a cellulose triacetate film, wherein the concentration of the organic solvent used for the dope in the dry gas in forming the cellulose triacetate film by the solution casting method is 1,000 ppm or less.

(16) When forming a cellulose triacetate film by the solution casting method, the concentration of the organic solvent used for the dope in the dry gas is 1,000 ppm or less, wherein (2) to (14). A method for drying a cellulose triacetate film according to any one of the above.

[0025]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in detail below.

FIG. 2 is a schematic view of a film casting apparatus according to the present invention. While drying a cellulose triacetate solution (hereinafter sometimes referred to as a dope) cast on a support 3 from a die 2, a dope film (hereinafter sometimes referred to as a web) 1 peeled at a peeling point 4 while drying is first dried. It is introduced into the zone 9, conveyed by a tenter, and dried by a drying gas blown from a blow dryer 10 above and below the web.
Further, there may be a pre-drying step without using a tenter before the first drying zone.

The shape of the outlet of the blow-out type dryer and the type of the dryer are shown in FIG. 11 with a long slit 19 type, and FIG. 13 shows a type with a plurality of slits 19 in one blow-out type dryer. Further, there are a kana-shape slit 21 shown in FIG. 15 and a punch plate dryer having a large number of round outlets 14 shown in FIG. 3, and the punch plate dryer has a uniform wind speed distribution and a uniform blow angle. It is a desirable dryer from the viewpoint of the production. When the amount of the residual solvent becomes 4% by weight or less, the web is drawn around by the roll group 6 in the second drying zone, dried by the introduced dry gas air 7, and finally cooled in the cooling zone 11 to be wound. It is taken up by the take-up machine 8. The dry gas air blown out from the blowout type dryer is discharged to the exhaust port 12 of the first drying zone.
Is discharged from The second drying zone may be of a tenter type, or may be a transport of a group of rolls as shown in FIG. 2, and a similar drying zone may be connected to the third and fourth zones.

FIG. 3 shows the punch plate 1 of the blow-out type dryer 10.
FIG. 3 is a plan view schematically showing an arrangement of round outlets 14 of a dry gas style (a plate provided as an outlet surface in an outlet type dryer and having many round outlets).

FIG. 4 is a sectional view of the first drying zone 9.
The dry gas wind blown from the blow-out dryer 10 located above and below the web 1 is indicated by an arrow 17, the angle between the web 1 and the dry gas wind 17 is θ, and h is the center of the punch plate 13 and the web 1. Shown as the distance.

FIG. 5 is a plan view of the punch plate 13. The arrangement of the outlets 14 of the punch plate 13 is shown.
The interval of No. 4 is indicated by a, and the diameter of the outlet 14 is indicated by b. 11 and 13 are plan views of the slit type dryer. FIG. 15 is a plan view of a slit dryer having a katakana-shaped V-shaped outlet.

FIG. 6 is a sectional view of the punch plate dryer 10. The embodiment in which the outlet 14 is embedded as a tube inside the punch plate dryer 10 is shown. This tube is called a straightening tube 15. Dry gas wind to punch plate dryer is inlet 1
Introduced from 6.

FIGS. 12 and 14 are sectional views of the slit type dryer. There is a flow straightening groove 20 having the same effect as the flow straightening tube 15 of FIG.

FIG. 7 is a schematic diagram showing the angle θ between the web 1 and the blown dry gas air 17.

FIG. 8 is a diagram showing the relationship between the width of the blow-out dryer and the width of the web, showing an embodiment in which the blow-dryer 10 is arranged wide from both ends of the web 1 by w and w '.

9 and 10 are plan views of the web 1, the blow-out dryer 10 and the dry gas air inlet 16 as viewed from above. FIG. 9 shows the introduction of the dry gas air from one direction, and FIG. 10 shows that the introduction ports 16 are introduced from both ends of the blowout type dryer 10.

The first point of the present invention is that the web 1 is kept in the first drying zone 9 between the time when the web 1 is peeled from the support 3 at the peeling point 4 and the time when the residual solvent amount becomes 4% by weight. While drying both ends of the web 1 by the tenter, the web 1 is dried by the drying gas blown out from the punch plate dryers 10 above and below the web 1. 7 is preferably between 30 ° and 150 °, as shown in FIG. 7, preferably between 60 ° and 120 °, and most preferably 90 °. The method of changing the angle at which the drying gas is applied to the web is performed by changing the angle of the whole blowout dryer. Further, it is preferable that the wind speed distribution of the dry gas blown out at that time is narrow, and when the distribution is based on the upper limit of the wind speed, it is important to narrow the difference between the upper limit value and the lower limit value to within 20% of the upper limit value. It is. To achieve this, the arrangement of holes in the punch plate,
This is due to the opening ratio of the outlet, the structure of the flow straightening tube, and the like. The opening ratio of the outlets is determined by the distance a between the holes and the diameter b of the holes in FIG.
The distribution is determined by the depth of the flow straightening tube into the punch plate dryer.

The second point of the present invention is that the wind speed of the dry gas air 17 impinging on the web 1 is reduced to a
When the amount of the residual solvent is less than 70% by weight and 4% or more, it is 0.5 m / sec or more and 40 m / sec or less when the amount of residual solvent is less than 70% by weight and 4% or more.
sec or less. When the amount of the residual solvent is large, it is easy to blow and generate unevenness unless performed at a relatively low wind speed. When the amount of the residual solvent is reduced, a strong air volume is preferable within this range.

In the third invention, in order to minimize the temperature unevenness with respect to the entire width of the web 1, when the upper limit of the gas temperature of the dry gas is used as a reference, the difference between the upper limit and the lower limit is set to the upper limit. It must be kept within 10%. For this purpose, there are various elements and means, but it is preferable to feed dry gas air from both sides of the blow-out dryer 10 as shown in FIG. As shown in FIG. 9, the air blow from one side is not very good at the balance point, and the degree of drying differs between the inlet side and the non-inlet side at the back.

According to a fourth aspect of the present invention, the balance of the amount of air blown from the blowout dryers 10 above and below the web 1 is as follows.
When the amount of the residual solvent is 4% by weight or more and 200% by weight or less, the ratio q (q = air amount on the upper surface of the web / air amount on the lower surface of the web) of the dry gas applied to the upper and lower sides of the web is 0.2 ≦ q ≦ 1. Is to balance and blow out. When the width of the web is narrow, a good quality cellulose triacetate film can be obtained by q = 1, but when the width of the web is wide, the slack becomes large due to the weight of the web, and the flutter of the web becomes severe due to the wind, Poor finish quality. Therefore, the larger the width, the smaller q, that is, by increasing the air volume on the lower side by 5 times, it is possible to improve the flatness even with a wide web. If it exceeds 5 times, the web flaps and surface properties, wrinkles, scratches, etc. are likely to occur.

According to a fifth aspect of the present invention, at least one kind of dry gas is used, and the average specific heat is 31.0 J / K · mo.
1 or more and 250 J / K · mol or less,
Drying can be performed more efficiently. This shortens the drying time due to the effect of increasing the heat transfer coefficient to the web. . As the gas having a high specific heat preferably used in the present invention, for example, water (3
3.6 J / K · mol or less), carbon dioxide (39.2 J / K
/ K · mol or less) methanol (46.4), ethanol (79.1), acetone (81.5) 1-butanol (118.8), pentane (135.1), hexane (163.6), Heptane (188.0) and octane (217.2) can be mentioned, and various gases can be combined. Therefore, nitrogen (28.9) or air (29.4) may be used as a mixture with the above gas. The specific heat of the mixed dry gas is expressed as follows.

Cp _mix = Cp ₁ × r ¹ + Cp ₂ × r ² + Cp ₃
× r ³ ... where Cp _mix is the specific heat of the mixed gas, Cp ₁ is the specific heat of gas 1, r ¹ is the mixing ratio of gas 1, Cp ₂ is the specific heat of gas 2, r
² is the mixing ratio of gas 2, Cp ₃ is the specific heat of gas 3, and r ³ is the mixing ratio of gas 3.

In the sixth invention, it is important that the gas having a high specific heat evaporating from the web is dried at a concentration that does not cause aggregation.

According to a seventh aspect of the present invention, the organic solvent obtained by evaporating the used exhaust gas from the web in a solvent recovery tower or the like is recovered, and the remaining dry gas is reused, or the whole or a part thereof is reused to reduce the cost. can do.

In the eighth invention, it is necessary to keep the concentration of the evaporated organic solvent in the dry gas at 1000 ppm or less from the viewpoint of safety.

Excellent effects can be produced by combining the above inventions, and especially when all the inventions are combined, the drying apparatus can obtain the maximum effect, and the drying apparatus that exhibits the maximum effect can be obtained. We can provide a method.

The amount of residual solvent used in the present invention was determined by measuring the web weight A by placing a web sampled at a measurement point in a weighing bin, and then measuring the web sample at 110 ° C.
After heating for 1 hour at room temperature, the mixture is cooled to room temperature so as not to adsorb moisture, weighed, and calculated according to the following formula using the weight B of the dried film.

Residual solvent amount (% by weight) = {(AB) / B} × 100 The average acetylation degree of the cellulose triacetate used in the present invention is 58.0% or more and 62.5% or less. In this case, this range will be referred to as cellulose triacetate. Generally, cellulose acetate having a degree of acetylation of 53% or more and 56% or less is called cellulose diacetate, and cellulose acetate having a degree of acetylation of 58% or more and 62.5% or less is called cellulose triacetate. In addition to the degree of acetylation, the indication of the degree of reactivity includes the degree of substitution or the degree of acetylation. The acetylation degree is expressed in terms of acetic acid (CH ₃ COOH)% by weight when acetic acid reacts with the hydroxyl group of cellulose, and is 62.5% when the acetic acid is reacted at the maximum. The degree of acetylation is expressed in terms of the acetyl group (CH ₃ CO) weight% at the time of the reaction, and is 44.8% at the highest reaction.
The degree of substitution represents the degree to which the acetyl group has reacted with the OH group of the cellulose molecule, and the case where all the OH groups have reacted is represented as 3.00. This means that three acetyl groups were substituted for three OH groups in the glucose unit, the minimum unit of the cellulose molecule. The degree of acetylation was measured using ASTM D-
817-97 can be measured by the method described in Test Methods for Cellulose Acetate and the like.

The polymerization degree (average viscosity) of the cellulose triacetate used in the present invention is preferably from 220 to 500. Generally, a cellulose triacetate film containing cellulose triacetate, the degree of polymerization is required to be 200 or more in order for the mechanical strength of the fiber or the molded article to be tough, and is described in "Cellulose Handbook" edited by Hiroshi Sobue and Nobuhiko Migita. Asakura Shobo (1985)
It is described in "Plastic Materials Course 17" edited by Hiroshi Marusawa and Kazuo Uda, Nikkan Kogyo Shimbun (1970). The polymerization degree of the cellulose triacetate film of the present invention is more preferably from 250 to 350. The viscosity average polymerization degree can be measured by an Ostwald viscometer, and is determined from the measured intrinsic viscosity [η] of the cellulose triacetate film by the following equation.

DP = [η] / Km In the formula, DP is a viscosity average degree of polymerization, and Km is a constant of 6 × 10 ^-4. Cellulose as a raw material of cellulose triacetate used in the present invention includes cotton linter and wood pulp. And cellulose triacetate from either of them can be used, or may be used as a mixture. Some raw materials have many low molecular weight components. JP-A-9-9
Nos. 5538, 9-95544 and 9-5557 disclose that cellulose triacetate having a low molecular weight easily undergoes crystallization in a cooling dissolution method, and the presence of fine crystals reduces the dissolution in acetone. Cellulose triacetate solution (hereinafter sometimes referred to as dope) has low stability, and microcrystals are easily generated again. It is further stated that the optical properties of the resulting film are also reduced.

The cellulose triacetate used in the present invention is preferably a photographic grade, and a commercially available photographic grade is obtained by satisfying qualities such as viscosity average polymerization degree, acetylation degree and low molecular weight component. Can be done. Manufacturers of photographic grade cellulose triacetate include Daicel Corporation, Coatles, Hoechst, Eastman Kodak, etc. Any photographic grade cellulose triacetate can be used.

The organic solvent of the cellulose triacetate solution used in the present invention includes methylene chloride, acetone, methyl acetate, fluoroalcohol (boiling point 40 ° C. or more and 165 ° C. or less), methyl acetoacetate, 1,3-dioxolan, 1,4- And dioxane.

In addition to the above-mentioned organic solvents, so-called poor solvents which promote solubility or increase the peeling rate and have little solubility in cellulose triacetate are also usefully used. For example, methanol, ethanol, propanol, 1-butanol, cyclohexanone and the like can be mentioned.

Plasticizers can be used in the present invention to increase the water resistance of the cellulose triacetate film and to improve the mechanical properties.

As the plasticizer, phosphoric acid esters, carboxylic acid esters, glycolic acid esters and the like are preferably used. Examples of phosphate esters include triphenyl phosphate (TPP), tricresyl phosphate (TCP), cresyl diphenyl phosphate (CDP).
P), octyl diphenyl phosphate (ODPP),
Examples include diphenylbiphenyl phosphate (BDP), trioctyl phosphate (TOP), and tributyl phosphate (TBP). Examples of carboxylic acid esters include dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), and dioctyl. Examples include phthalate (DOP), diethylhexyl phthalate (DEHP), dibutyl sebacate (DBS), and examples of glycolic acid esters include triacetin (TA), ethylphthalylethyl glycolate (E
PEG), methylphthalylethyl glycolate (MPE)
G) and the like, and are preferably used. Particularly, TPP, DEP, EPEG, and BDP are preferable. These plasticizers may be used alone or in combination of two or more.
The amount of the plasticizer added is 5 to cellulose triacetate.
It is preferable that the content be in the range of 8% by weight to 16% by weight. These compounds may be added together with the cellulose triacetate and the solvent during the preparation of the cellulose triacetate solution, or may be added during or after the solution preparation.

[0055]

EXAMPLES The present invention will be described below in detail with reference to examples, but embodiments of the present invention are not limited thereto.

(Basic conditions) The conditions for forming the cellulose triacetate film described here are basic, and are the basis of the conditions in the following examples. Using a dope consisting of 100 parts by weight of cellulose triacetate, 350 parts by weight of methylene chloride, ethanol and 12 parts by weight of TPP, a dope film was formed on a stainless steel belt running endlessly having a mirror surface from a die, and when the belt was rotated substantially once. The web is dried in the drying zone shown in FIG. 2 after the peeling and the amount of the residual solvent at the entrance of the first drying zone is set to 130%.

In the first drying zone, a drying gas is blown out from a punch plate dryer positioned above and below the web while being transported by a tenter to perform drying. The drying gas temperature here is 60 ° C. Thereafter, the cellulose triacetate film is dried at 90 ° C. in the second drying zone and subsequently at 100 ° C. (for example, in the third drying zone), and then cooled to room temperature and wound up. The thickness of the cellulose triacetate film is set to 120 μm.

(Measurement of Planarity) The cellulose triacetate film thus prepared was scanned at 10 points in the width direction of the film by a probe with a stylus type three-dimensional surface roughness meter surf coder manufactured by Kosaka Laboratories, and each point was scanned by 10 mm. The flatness was evaluated by the average value of the obtained center line average roughness: Ra (μm) at five points.

Example 1 In a first drying zone, as shown in FIG. 8, a punch plate dryer 10 having a width w 200 mm wider than both edges in the width direction of the web at regular intervals in the web transport direction is provided. The dry gas blowing angle (θ in FIGS. 4 and 7) at the blowing port 14 of each punch plate 13 was set to 80 ° with respect to the plane of the web.
The distance between the punch plate dryer and the film (h in FIG. 4) was 100 mm for each of the upper and lower sides. The diameter (14, b in FIG. 5) of the outlet of the punch plate is set to 10 mm, and the interval between the outlets (a in FIG. 5) is arranged at intervals of 10 mm in the width direction of the web. The center of a was aligned with the center, and the intervals between all the outlets were made equidistant, and the entire processed portion was arranged. Also, a flow straightening tube was attached to the outlet as shown in FIG. 6 so that the dry gas wind was emitted perpendicularly from the punch plate. Using this dryer, air at 60 ° C.
Blowed in sec. When the wind speed was measured near the web surface with a portable anemometer manufactured by Nippon Kanomax Co., Ltd., 10.5 to 9.8 m / sec was measured, and the difference between the upper and lower limits of the wind speed was 6. 7%. Thereafter, the film was dried and wound up according to the basic conditions to obtain a cellulose triacetate film.

[Comparative Example 1] As a comparison, drying was performed by setting the drying gas blowing angle θ of the punch plate dryer at 10 ° and the distance h between the blow-out opening of the punch plate and the web at 100 mm, and drying the same. After drying and winding, a comparative cellulose triacetate film was obtained.

Table 1 shows the results.

[0062]

[Table 1]

(Results) Film 1 was small in surface roughness and excellent in flatness. The surface roughness of the comparative film 1 was very large and the flatness was poor. First
Sampling was performed at the outlet of the drying zone, and when the amount of the residual solvent was measured, the difference in the drying from 22% by weight to Comparative 1 was clearly small. In comparison, it is considered that the blowout angle θ was small and sufficient heat transfer was not obtained.

[Example 2] In the first drying zone, Example 1 was used.
Using the same drying device as above, the amount of residual solvent at the time of peeling the belt was 130 wt% and 100 wt%, and the blowing speed of air was 10 m / sec and 15 m / sec.
10 m for a web having a residual solvent amount of 68% by weight.
/ Sec, 15 m / sec and 25 m / sec, and dried to obtain a cellulose triacetate film.

[Comparative Example 2] The amount of residual solvent at the time of peeling was 130
The webs of 100 wt% and 100 wt% were blown with air and dried at an air velocity of 25 m / sec to obtain a comparative cellulose triacetate film.

Table 2 shows the results.

[0067]

[Table 2]

(Results) It is within the scope of the present invention to apply a dry gas wind at a high air velocity to a web having a large amount of residual solvent to increase the surface roughness, thereby improving the flatness and drying at a high speed. Is good.

Example 3 Dry gas at 60 ° C. was supplied to the punch plate dryer in the first drying zone from both sides as shown in FIG. When the temperature distribution in the punch plate dryer at this time was examined, the lower limit was 57 ° C., and the ratio of the difference between the upper limit and the upper limit temperature of 60 ° C. was 5%.

COMPARATIVE EXAMPLE 3 As shown in FIG. 9, a dry gas was supplied to one side of a punch plate dryer, and the residual solvent of the dry gas supply side and the web not supplied were sampled at the outlet of the first drying zone. Measured.

Table 3 shows the results.

[0072]

[Table 3]

(Results) When the drying gas was supplied from both sides, there was almost no temperature unevenness in the punch plate dryer, whereas in the comparative example supplied from one side, the temperature unevenness was severe, and the drying did not proceed on the side opposite to the supply side. The cellulose triacetate film had unbalanced properties.

Example 4 Drying was performed by changing the balance q of the drying gas blown from the punch plate dryers above and below the web in the first drying zone.

[Comparative Example 4] Similarly to Example 4, drying was performed with the air volume ratio q set to 0.1.

Table 4 shows the results.

[0077]

[Table 4]

(Results) The air flow balance q above and below the web was changed from 0.2 to 1.0, but a good cellulose triacetate film was obtained with good dryness and flatness. As a comparison, when the lower side was dried with an air volume 10 times as high as that of the upper side, wrinkles occurred and wrinkles occurred, and deterioration in flatness was observed.

Example 5 A web having a large specific heat was mixed with a dry gas blown from a punch plate dryer to dry the web. Air is converted to nitrogen gas (Cp = 28.9 J / Km)
ol, 60 ° C.), and when passing pentane gas (Cp = 135.1 J / K · mol, 60 ° C.) as a gas having a high specific heat through the drying zone having the lowest temperature, the gas is heated at 60 ° C. so that condensation does not occur. 40% of the saturated vapor pressure of
4 hPa). A mixed gas of nitrogen gas and pentane gas was used.

Comparative Example 5 As a comparison, drying was performed using argon (Cp = 20.8 J / K · mol, 60 ° C.) as a dry gas.

Table 5 shows the results.

[0082]

[Table 5]

(Results) The argon gas as the comparative drying gas had a significantly lower drying rate than the mixed gas of the present invention, and the flatness was also deteriorated.

[0084]

According to the present invention, a drying apparatus and a method which can be produced at high speed and high efficiency while being compact can be developed, and a low cost cellulose triacetate film can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic view of a conventional solution casting film forming apparatus.

FIG. 2 is a schematic diagram of a solution casting method film forming apparatus of the present invention.

FIG. 3 is a plan view of a punch plate.

FIG. 4 is a sectional view of a first drying zone.

FIG. 5 is a plan view of one embodiment of a punch plate.

FIG. 6 is a sectional view of a punch plate dryer.

FIG. 7 is a schematic view showing an angle between a dry gas wind blown from a blowout type dryer and a web plane.

FIG. 8 is a view showing the relationship between the width of a blow-type plate dryer and the width of a web.

FIG. 9 is a plan view of one embodiment in which the blow-out dryer has a dry gas inlet on one side.

FIG. 10 is a plan view of an embodiment in which a blow-out type dryer has drying gas inlets on both sides.

FIG. 11 is a plan view of a blow dryer (slit dryer) having a slit blow outlet.

FIG. 12 is a sectional view of a slit type dryer.

FIG. 13 is a plan view of a slit dryer having a plurality (two) of slit outlets.

FIG. 14 is a cross-sectional view of a slit dryer having a plurality (two) of slit outlets.

FIG. 15 is a plan view of a slit dryer having a C-shaped slit outlet.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 web 2 casting die 3 support 4 peeling point 5 drying zone 6 roll group 7 drying gas wind 8 winder 9 first drying zone 10 blow-out dryer (punch plate dryer) 11 cooling unit 12 exhaust outlet 13 blowout Punch plate (punch plate) of mold dryer 14 Blow-out port 15 Rectifier tube 16 Dry gas inlet 17 Blow-out dry gas 18 Blow-out surface of slit-type dryer 19 Slit 20 Rectifying groove 21 C-shaped slit a Punch plate blow-out port Spacing b Diameter of punch plate outlet h Distance between web and center of punch plate w and w 'Distance between both ends of wide punch plate and edges of web θ Angle between dry gas blowing direction and web plane

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kazuyuki Shimizu, Konica Corporation, 1 Sakuracho, Hino-shi, Tokyo In-house (72) Inventor Masami Akira Konica Corporation, 1 Sakuracho, Hino-shi, Tokyo

Claims (16)

[Claims] Claims: 1. A portion for casting a cellulose triacetate solution on a support that runs endlessly, drying the web by flowing a dry gas while transporting the web by a tenter after peeling the web from the support, In forming a cellulose triacetate film by a solution casting method in which a drying gas is blown out toward a web from a blowout dryer having blowout ports located above and below the web conveyed in the tenter, the web is separated from the support. After peeling, before the amount of the residual solvent in the web becomes 4% by weight, the blowing angle from the blowing port is in the range of 30 ° to 150 ° with respect to the film plane, and the drying gas blowing extending direction. When the wind speed distribution on the film surface located at the upper limit of the wind speed is set as a reference, the difference between the upper limit value and the lower limit value is set to 20 of the upper limit value. %, A drying gas is blown out, and the web is dried to dry the web. 2. A part for casting a cellulose triacetate solution on a support running endlessly, drying the web by flowing a drying gas while transporting the web by a tenter after peeling the web from the support, and In forming a cellulose triacetate film by a solution casting method in which a drying gas is blown out toward a web from a blowout dryer having blowout ports located above and below the web conveyed in the tenter, the web is separated from the support. After the film is peeled off, until the amount of the residual solvent in the web becomes 4% by weight, the blowing angle from the blowing port is in the range of 30 ° to 150 ° with respect to the plane of the film, and the blowing and extension of the drying gas is performed. When the wind speed distribution on the film surface located in the direction is based on the upper limit value of the wind speed, the difference between the upper limit value and the lower limit value is defined as 2 of the upper limit value. A method for drying a cellulose triacetate film, wherein the drying is performed by blowing a drying gas within 0%. 3. A method for forming a cellulose triacetate film by the solution casting method, wherein when a residual solvent amount in the web is 130% by weight or less and 70% by weight or more, a web of a dry gas blown out from the blow-out type dryer is used. When the wind speed on the surface is 0.5 m / sec or more and 20 m / sec or less, and the residual solvent amount is less than 70 wt% and 4 wt% or more, the wind speed of the dry gas is 0.5 m / sec or more and 40 m / sec.
A method for drying a cellulose triacetate film, characterized by drying by a dry gas wind blown out in seconds or less. 4. When forming a cellulose triacetate film by the solution casting method, when the amount of residual solvent in the web is 130% by weight or less and 70% by weight or more, the wind speed of the dry gas on the web surface is 0.5 m / Sec or more 20
m / sec or less, and when the residual solvent amount is less than 70% by weight and 4% by weight or more, the dry gas blown at a wind speed of 0.5 m / sec or more and 40 m / sec or less on the web surface of the dry gas. 3. The method according to claim 2, wherein the drying is performed.
4. The method for drying a cellulose triacetate film according to the above. 5. When forming a cellulose triacetate film by the solution casting method, when the temperature distribution of the dry gas in the width direction of the web is based on the upper limit value of the gas temperature, the difference between the upper limit value and the lower limit value is determined. Is within 10% of the upper limit of the cellulose triacetate film drying method. 6. In forming a cellulose triacetate film by the solution casting method, when the temperature distribution of the dry gas in the width direction of the web is based on the upper limit of the gas temperature, the difference between the upper limit and the lower limit is determined. The method for drying a cellulose triacetate film according to any one of claims 2 to 4, wherein the upper limit value is within 10% of the upper limit value. 7. A blowout dryer positioned above and below a conveyed web when a residual solvent amount in the web is 4% by weight or more and 200% by weight or less in forming a cellulose triacetate film by the solution casting method. Wherein the air flow ratio q (q = air flow on the upper surface of the web / air flow on the lower surface of the web) of the dry gas blown out from the blowout port is 0.2 ≦ q ≦ 1. 8. A blowout dryer positioned above and below a conveyed web when a residual solvent amount in the web is 4% by weight or more and 200% by weight or less in forming a cellulose triacetate film by the solution casting method. 7. The airflow ratio q (q = airflow on the upper surface of the web / airflow on the lower surface of the web) of the dry gas blown out from the blowout port of (2) satisfies 0.2 ≦ q ≦ 1. A method for drying a cellulose triacetate film. 9. In forming a cellulose triacetate film by the solution casting method, at least one kind of gas is used as a drying gas, and its average specific heat is 31.0 J.
/ K · mol or more and 250 J / K · mol or less, a method for drying a cellulose triacetate film. 10. When forming a cellulose triacetate film by the solution casting method, at least one kind of gas is used as a drying gas, and its average specific heat is 31.0%.
The method for drying a cellulose triacetate film according to any one of claims 2 to 8, wherein the content is not less than J / K · mol and not more than 250 J / K · mol. 11. When forming a cellulose triacetate film by the solution casting method, the concentration of an organic compound in a liquid at room temperature contained in a drying gas during drying is 50%.
%. A method for drying a cellulose triacetate film, characterized by drying with a dry gas having a saturated vapor pressure of not more than 10%. 12. When forming a cellulose triacetate film by the solution casting method, the concentration of an organic compound in a liquid at room temperature contained in a dry gas during drying is 50%.
The method for drying a cellulose triacetate film according to any one of claims 2 to 10, wherein the drying is performed with a drying gas having a saturated vapor pressure of not more than 10%. 13. A method for forming a cellulose triacetate film by the solution casting method, wherein all or a part of an organic solvent of an exhaust gas of a dry gas after web drying is recovered and reused as a dry gas. For drying a cellulose triacetate film. 14. A method for forming a cellulose triacetate film by the solution casting method, wherein all or a part of an organic solvent of an exhaust gas of a drying gas after web drying is recovered and reused as a drying gas. The method for drying a cellulose triacetate film according to any one of claims 2 to 12. 15. A method for drying a cellulose triacetate film, wherein a concentration of an organic solvent used for dope in a dry gas is 1000 ppm or less when forming a cellulose triacetate film by the solution casting method. 16. The organic solvent used for dope in a dry gas in forming a cellulose triacetate film by the solution casting method has a concentration of 1000 ppm or less. Drying method for cellulose triacetate film.