JPH1177719A - Apparatus and method for producing cellulose triacetate film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the contamination generated within a tenter and to remove a generated contaminant by providing heating parts in the clips of the tenter in forming a cellulose triacetate film by using a soln. casting method using the tenter. SOLUTION: When a cellulose triacetate film is formed by a soln. casting method using a tenter, the clips 20 of the tenter have heating parts 21 built therein. The heating parts 21 built in the clips 20 are heat generators emitting heat upon energization and, for example, composed of nichrome wires. The heating parts 21 are built in both of a fixed stand 12 and the shoe 11 holding the film from above and heat a web 1 from both upper and lower surfaces thereof to carry the web 1. The heating parts 21 built therein are only built in the fixed stand and the fixed stand generates heat to transmit the same to a pin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a cellulose triacetate film useful for a silver halide photographic material or a liquid crystal image display, and an apparatus for producing the same. More specifically, the present invention relates to an apparatus and a method for producing a cellulose triacetate film of high quality without contamination when producing a cellulose triacetate film having a step of drying while transporting the cellulose triacetate film by a tenter.

[0002]

2. Description of the Related Art Schematic diagrams of a solution casting film forming method are shown in FIGS. A dope obtained by dissolving cellulose triacetate in a solvent such as methylene chloride is quantitatively sent to a die 2 by a pressure gear pump or the like, and is cast from the die 2 onto a metal support 3 having a mirror surface running endlessly. This is a method in which the web 1 is peeled off at a peeling point 4 before the film makes one round, dried by a drying air 5 in a drying box 5 through a roll group 6, and wound up to produce a cellulose triacetate film. In addition, as shown in FIG. 2, after peeling, the sheet is transported by a tenter 8 and dried.

[0003] One of the stretching methods performed to improve the mechanical strength and the like of a film such as polyester or polypropylene is to fix both side edges of the film with clips or the like.
There is a tenter method for stretching up 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 using this tenter method has also been developed (Japanese Patent Application Laid-Open No. 59-211006), and it is known that a cellulose triacetate film can be used for this film. Suggested during. On the other hand, one of the methods for producing a cellulose triacetate film is a solution casting film forming method in which a dope is cast on a casting surface of a support, for example, a belt or a drum, and the dope is separated and dried. In order to prevent width shrinkage due to drying in the process of drying the web from which the dope has been peeled off, a method of drying while transporting while holding both edges of the web with a tenter is described in Japanese Patent No. 2076430.

In FIGS. 4, 5, 6, and 9, generally, tenter clips include a clip 9 for holding the web 1 and pressing it and a pin-type clip 13 for inserting the web 1 into a number of pins. Most of the polyester width stretching tenters are of the type of pinching (holding), and a large number of clips 9 (in FIGS. 6 and 9, clips 9) are provided along endless loop rails 18 on both sides of the stretching machine. Are drawn), and the clipped web 1 driven by the chain 19 which is movable by the sprocket 17 is conveyed. After the clip 9 releases the web 1, it returns to its original position along the outer rail 18, and carries and transports the web again. In general, after the web is released, the polyester film is stretched at a high temperature after the web is released, and the web is generally allowed to cool as long as the web is not carried by the clip.

[0005]

In the method of producing a cellulose triacetate film using a tenter, dirt often occurs, which affects the flatness of the film and the coatability of a silver halide photosensitive photographic emulsion. In order to further improve the productivity, there is a need to stop the production for further removal of dirt or to decompose the production, thereby greatly reducing the productivity.

[0006] This phenomenon and its cause will be described. After the web is peeled off, it is transported and dried while being held on the clip and holding or stretching the width.After the released web is released from the clip, when the clip comes to the position where the web is added again, it remains on the clip. Debris can have various adverse effects on the new web. Foreign matter adhering to the clip is the one that remains sticky when the web is held when it is soft and becomes solid after drying, or the debris that is peeled off when released, plasticizer deposits, etc. There is, however, the dry wind splatters on the web that is scattered or becomes a large lump with clips, causing wrinkles and distortions from the edge of the web to the inside, impairing the flatness, and silver halide photosensitive photography After coating the emulsion, the photographic layer also had non-uniform portions, which had various adverse effects.

An object of the present invention is to prepare a cellulose triacetate film using a tenter,
By preventing the generation of foreign substances such as dirt generated in the tenter, and by removing foreign substances such as generated dirt, it has excellent quality such as flatness and coatability of the film,
It is an object of the present invention to provide a method and an apparatus for producing a cellulose triacetate film capable of producing a cellulose triacetate film having high productivity.

[0008]

Means for Solving the Problems In order to achieve the above-mentioned object, the invention has been achieved by the following constitutions (1) to (6).

(1) An apparatus for producing a cellulose triacetate film, wherein a clip of the tenter has a built-in heating part when the cellulose triacetate film is formed by a solution casting method using a tenter.

(2) In forming a cellulose triacetate film by a solution casting method using a tenter, the clip on the tenter is released from the time when the clip is released to the time when the web is carried again. An apparatus for producing a cellulose triacetate film, comprising: an apparatus for removing foreign matter generated at a contact portion of a cellulose triacetate film.

(3) The apparatus for producing a cellulose triacetate film according to (2), wherein the clip has a built-in heating portion.

(4) Production of a cellulose triacetate film characterized in that, when a cellulose triacetate film is formed by a solution casting method using a tenter, the web is transported while supporting the web with a clip having a built-in heating part. Method.

(5) When a cellulose triacetate film is formed by a solution casting method using a tenter, the clip of the tenter is released from the web until the clip is carried again. A method for producing a cellulose triacetate film, comprising removing foreign matter generated at a contact portion of a cellulose triacetate film.

(6) The foreign matter is removed by using a jetting gas or liquid and a brush (5).
3. The method for producing a cellulose triacetate film according to 1.).

[0015]

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

The clip used in the present invention includes a clip 9 generally used in a polyester film stretching apparatus as shown in FIG. 4 or a pin type clip 13 as shown in FIG. , Both are useful.

As shown in FIG. 7 or FIG. 8, the first aspect of the present invention is a clip 20 having a structure in which a heating portion 21 is built in (enclosed). The heating part 21 contained in the clip is a heating element that generates heat when energized, for example, a nichrome wire. In the present invention, any heating element that generates heat when energized can be used. The heating part 21 is built in both the fixed base 12 and the shoe 11 sandwiched from above, and is heated and supported from both upper and lower surfaces of the web 1. FIG. 8 shows a schematic view of a pin-type clip 22 having a built-in heating part.
The fixing table 14 shown in FIG. 8 generates heat, and the heat is transmitted to the pin 15.
The amount of residual solvent at the time of contact between the clip or pin and the web is preferably 12% by weight or more and 50% by weight or less, and the surface temperature of the portion where the clip or pin contacts the web is 60 ° or more and 200 ° or less, particularly 80 ° C. It is preferably at least 120 °.

The heating section is energized by a conductor in the chain of the tenter.

It has been found that when heat is applied to the portion of the clip that is in contact with the web, the drying of the portion is accelerated and that web debris is less likely to appear when the clip is released, and that the adhesion of the plasticizer to the clip is significantly reduced. As a result, it has been found that not only the labor and labor required for cleaning the clip can be saved, the productivity can be improved, but also a high-quality cellulose triacetate film can be produced.

The outline of the second invention will be described with reference to FIG. 9. The clip 9 releases the web at the web release section 23, and thereafter the clip is turned around the sprocket 17 on the side opposite to the web side of the tenter, the cleaning section 24 and the drying section 24. Through the hood 27 divided into the section 25, the web 1 introduced again by the support section 26 is carried, and the width of the web is held in the tenter or stretched in the width direction. 2
In 4, a dirt is removed and cleaned with a jetting gas or liquid and with a brush. The drying section 25 is an area where the clip is dried when the cleaning section 24 uses the liquid. The cleaning unit 24 and the drying unit 25 are covered with a hood 27 so as to prevent contamination of the inside of the tenter because foreign matters removed from them come out. It prevents the spread of dirt.

As described above, the second aspect of the present invention is a method and an apparatus for removing foreign matter generated at a web contact portion of a clip by jetting gas or liquid. As a removing method, a cleaning nozzle 29 with a brush 32 as shown in FIG. 10 is used. The cleaning nozzle 29 with the brush 32 has a large number of injection ports 31, from which gas or liquid is injected from the inside to blow off foreign matter of the clip. A bristle brush 32 is provided to physically remove dirt.
The cleaning nozzle 29 is also rotatable. The material of the brush is not particularly limited as long as it is a usual bristle for a brush, but pig hair is preferably used. FIG. 11 is a conceptual diagram showing a positional relationship between the clip 9 and a cleaning nozzle 29 with a brush during cleaning.

As the gas to be injected, air or nitrogen gas is used. As liquids, water, methylene chloride, fluoroalcohol, 1,3-dioxolan, 1,
4-Dioxane, methyl acetate and the like can be used, but water with the lowest risk is preferred.

As described above, the foreign matter generated at the portion where the clip and the web come into contact with each other is, for example, a scum that has been cut off from the web, a cut end, an adhered substance obtained by solidifying the plasticizer vapor, and the like. Refers to all foreign substances generated in the periphery.

The solution casting method used in the present invention is generally a method for forming a cellulose triacetate film. That is, cellulose triacetate is dissolved in a good solvent for cellulose triacetate, for example, methylene chloride or the like to form a dope, which is quantitatively sent to a dice by a pressure gear pump or the like, and cast on a support. The dope film is a method of producing a cellulose triacetate film by separating the dope film by making a round around the support, transporting the web by a tenter and drying, and further drying through a tenter or a roll group if necessary.

The average acetylation degree of the cellulose triacetate used in the present invention is 58.0% or more and 62.5% or less, and in the present invention, this range is called cellulose triacetate. Generally, cellulose acetate having an acetylation degree of 53% or more and 56% or less is called cellulose diacetate, and has an acetylation degree of 58% or more and 62.5%.
The following are called cellulose triacetates.
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 was determined by the acetyl group (CH ₃
CO) in weight percent, with 4
4.8%. 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 can be measured by a method described in ASTM D-817-97, such as a test method for cellulose acetate.

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 of the present invention is more preferably 25.
0 to 350. The viscosity average polymerization degree can be measured with an Ostwald viscometer, and is determined from the measured intrinsic viscosity [η] of cellulose triacetate by the following formula.

DP = [η] / Km where DP is the viscosity-average degree of polymerization, Km is a constant of 6 × 10 ^-4 methylene chloride, acetone, methyl acetate, and fluorocarbon are used as the organic solvent for the cellulose triacetate solution used in the present invention. Alcohol (boiling point 40 ° C or higher and 165 ° C or lower), methyl acetoacetate, 1,3-dioxolan, 1,
4-dioxane and the like.

In addition to the above 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.

A plasticizer can be used in the present invention to increase the water resistance of the cellulose triacetate film or 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.

[0031]

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

(Example 1) Cellulose triacetate 1
00 parts by weight, 380 parts by weight of methylene chloride, 50 parts by weight of ethanol and 12 parts by weight of triphenyl phosphate (plasticizer) were mixed and dissolved to obtain a dope. A pressurized type gear pump capable of precisely feeding the solution was cast from a coat hanger type die so that the thickness of the cellulose triacetate film was 125 μm. Dried on the support, peeled off after about one round,
The web was introduced into a tenter, and both ends were gripped with clips to maintain the width so that the width did not shrink. A clip having a built-in heating portion was used, and the surface temperature of the web contact portion of the clip was 90 ° C. The drying air in the tenter was dried at 60 ° C. at the beginning, 90 ° C. in the middle and 110 ° C. in the latter half. After leaving the tenter, pass through the roll group dryer
The film was dried at 20 ° C. and wound up to obtain a cellulose triacetate film roll of 500 m. One sample was taken out from a position of 500 m from the beginning as a sample and used for evaluation.

(Evaluation method) <Flatness> Each sample was cut out to a size of 90 cm in width and 100 cm in length, and five 50 W fluorescent lamps were arranged side by side on the sample stand.
Fixed at a height of 1.5 m to illuminate from an angle of °, placed each film sample on the sample stage, visually observed the unevenness reflected on the film surface, and judged as follows .

A: All five fluorescent lamps looked straight B: Some fluorescent lamps seemed to bend slightly C: Fluorescent lamps seemed to be slightly bent D: Fluorescent lamps seemed to undulate E: Fluorescent Small undulations can be seen even in large turns with large lights.

<Unevenness of Coating> An undercoat layer and a back layer having the following formulation were applied to each film and dried, and a gelatin solution containing the following dye was applied and dried on the undercoat surface.

(Undercoat coating solution) Vinyl acetate: maleic anhydride alternating copolymer 3 g Acetone 810 g Isopropanol 150 g (Back layer coating solution) Tin oxide: antimony oxide composite fine particles (average particle diameter 0.05 μm) 14 g Cellulose diacetate 6 g Acetone 800 g Cyclohexanone 200 g (Gelatin coating solution) Gelatin 4 g Water 100 g Methyl violet (dye) 0.2 g Saponin 0.1 g Each sample was placed on a charkasten, and coating unevenness was evaluated as follows.

A: very smooth without unevenness B: slight fine unevenness C: slightly uneven feeling D: clear unevenness visible E: very large unevenness visible

(Embodiment 2) The clip is not of the heating type, and after the clip releases the web, the cleaning nozzle 24 with the brush 32 shown in FIG. 10 is set in the cleaning section 24 in the hood 27 shown in FIG. And sprayed with 50 ° C. water at a rate of 50 cc / sec per second.
A film was prepared in the same manner as in Example 1 except that air at 0 ° C. was blown at a speed of 100 cc / sec / second to dry the clip, and a cleanness in the tenter was maintained. Provided.

(Example 3) A film was prepared in the same manner as in Example 2 except that a clip having a built-in heating portion was used and the temperature of the contact portion of the clip with the web was 90 ° C. 1 sample from 500m from the beginning
One sheet was cut out and used for evaluation.

(Comparative Example) A film was produced in the same manner as in Example 1 except that a normal clip having no heated portion was used. Similarly, one comparative sample was cut out from a place of 500 m and subjected to evaluation. .

The results are shown in Table 1.

[0042]

[Table 1]

(Results) The samples of Example 1 and Example 2 were hardly stained and had no problem in flatness and coatability, but the film of the comparative example had very poor flatness and coatability. Note that the film shown in Example 3 and using the clip having a built-in heating part and washed and dried in the washing part and the drying part in the tenter showed the best flatness and coatability.

[0044]

In producing a cellulose triacetate film using a tenter, factors that deteriorate the flatness and coatability due to foreign matter that easily occurs in the tenter are as follows.
By incorporating a heating portion in the clip or by equipping the clip with a cleaning device, a cellulose acetate film having excellent flatness and coatability could be produced.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a solution casting method of cellulose triacetate film.

FIG. 2 is a schematic diagram of one embodiment of a solution casting method for cellulose triacetate film using a tenter immediately after peeling.

FIG. 3 is a schematic diagram of one embodiment of a solution casting method for cellulose triacetate film using a tenter after drying.

FIG. 4 is a side view of a clip;

FIG. 5 is a conceptual diagram of a pin-type clip.

FIG. 6 is a schematic plan view of a tenter.

FIG. 7 is a conceptual side view of a clip having a built-in heating portion.

FIG. 8 is a conceptual diagram of a pin-type clip having a built-in heating part.

FIG. 9 is a plan view of a tent and a tenter having a washing unit and a drying unit.

FIG. 10 is a sketch drawing of a cleaning nozzle with a brush.

FIG. 11 is a conceptual diagram illustrating a positional relationship between a cleaning nozzle with a brush and a clip during cleaning.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Web 2 Die 3 Support 4 Peeling point 5 Drying box 6 Roll group 8 Tenter 9 Clip 10 Lever 11 Shu 12 Fixing stand 13 Pin type clip 14 Fixing stand 15 Pin 16 Tenter 17 Sprocket 18 Rail 19 Chain 20 Clip 21 Built-in heating part 22 Clip (built-in heating part) 23 Clip release part 24 Cleaning part 25 Drying part 26 Carrying part 27 Hood 28 Exhaust port 29 Cleaning nozzle 31 Injection port 32 Brush

Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08L 1/12 C08L 1/12 B29K 1:00 B29L 7:00

Claims (6)

[Claims] 1. An apparatus for producing a cellulose triacetate film, wherein when the cellulose triacetate film is formed by a solution casting method using a tenter, a clip of the tenter has a built-in heating part. 2. In forming a cellulose triacetate film by a solution casting method using a tenter, the clip of the tenter is released after the clip of the tenter releases the web and before the web is supported again. An apparatus for producing a cellulose triacetate film, comprising: an apparatus for removing foreign matter generated in a contact portion. 3. The apparatus for producing a cellulose triacetate film according to claim 2, wherein the clip has a built-in heating portion. 4. A method for producing a cellulose triacetate film, which comprises transporting a cellulose triacetate film while supporting the web with a clip having a built-in heating portion when forming the cellulose triacetate film by a solution casting method using a tenter. . 5. When a cellulose triacetate film is formed by a solution casting method using a tenter, the clip of the tenter is released from the time when the clip of the tenter releases the web to the time when the web is supported again. A method for producing a cellulose triacetate film, comprising removing foreign matter generated at a contact portion. 6. The method for producing a cellulose triacetate film according to claim 5, wherein the foreign matter is removed using a gas or liquid to be sprayed and a brush.