JPS62115035A - Production of cellulose triacetate film - Google Patents

Abstract

PURPOSE:To produce the title film which has neither foam nor warpage in a high yield, by casting a specified solvent mixture contg. cellulose triacetate on a support and conveying the resulting film while tension is applied crosswise to the film. CONSTITUTION:18-35wt% mixture of cellulose triacetate and other component which is solidified after drying [e.g., triphenyl phosphate] and a solvent mixture of 87-75wt% methylene chloride and 13-25wt% other solvent (e.g., methanol) are placed in a pressure vessel and heated at 60 deg.C or above in an inert gas atmosphere to dissolve them and the soln. is cooled to obtain a dope 4. The dope 4 is cast on a support 4 which is cooled to 10 deg.C or below from a casting part 1 to a stripping part 2, dried and stripped to obtain a cellulose triacetate film 5. The both side edges of the film 5 is fixed by means of a tenter 6 and the film is travelled in zigzag manner through a dryer 8 and a dried by hot air 9.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing a cellulose triacetate film used as a support for photographic light-sensitive materials.

[Conventional technology]

Methylene chloride or a mixed solvent of methylene chloride and about 10% alcohol is generally used as a solvent when cellulose triacetate is formed into a film using the solution casting method. Because the speed is extremely slow, cellulose triacetate) K
Methanol, which is a poor solvent for the reaction, is further added.

However, since this methylene chloride-methanol mixed solvent still has a slow coagulation rate and takes time to peel off from the support, various studies have been conducted to improve it. For example, U.S. Patent Nos. 2,607,704 and 2,739.
, No. 069, Japanese Patent Publication No. 45-9074, Japanese Patent Publication No. 54-4
Various specifications such as No. 8862 disclose a method of promoting gluing by adding a poor solvent such as butanol or cyclohexane. Further, US Pat. No. 2,221,019 discloses a method of cooling cast dough to prevent gluing. U.S. Patent No. 3,793,043
The issue discloses a method of promoting glulation using metal salts.

On the other hand, a technology has also been reported that reduces the time required for stripping after casting to less than 5 minutes by casting a dope such as cellulose acetate glopionate onto a cooled drum and then air-drying and stripping it. (U.S. Patent No. 2.319,052
issue).

In addition, when a film is formed by this solution casting method, the drying method after peeling is generally as shown in Fig. 24.
The film 5 (hereinafter sometimes referred to as "web") peeled off from the support is passed through a number of rolls 41, 41. ... A method has been used in which the material is dried using hot air 9, infrared rays, etc. while passing between the parts (for example, US Pat. No. 2,319,053).

A method has also been developed in which the Kuep is not hung directly on the roll, but air is blown out and the 9 nibs are floated by the pressure, thereby moving the Kuep in a non-contact state with the hanging body (for example, Japanese Patent Publication No. 135046/1983). Such).

On the other hand, one of the stretching methods used to improve the mechanical strength of films such as polyester and polypropylene is to fix both side edges of the film with clips, etc.
There is one type of tenter that doubles stretching. A technology has also been developed to use this tenter system to manufacture substrates for liquid crystal displays and mother panels from films such as phenoxy resin (1986).
211006), it is suggested that a cellulose triacetate film can also be used for this film.

[Problem that the invention seeks to solve]

In the method of promoting gluing by adding a poor solvent such as butanol or cyclohexane or a metal salt, the support is rotated once after casting on an endless band or drum (hereinafter collectively referred to as the support). In the meantime, the solvent must be evaporated from the casting layer at least until it can be peeled off from the support, solidified, and peeled off from the support. However, it takes quite a while for the hair to dry before it can be peeled off.

In such a method, the amount of solvent in the film at the time of peeling is generally limited to about 100% of the weight of the film after drying. Therefore, for example, % Kaisho 54-48862
As shown in the example of the publication, the upper limit speed at which the peeling is possible is 1.0 to 1.1 m/m when there are few gluing solvent caps.
Even when crystallizing an appropriate amount of gluing solvent, the drying time is approximately 330 seconds for a band with a circumference of 6 m.
．． 6 m/min (drying time for a 6 m band per circumference is about 140 seconds). For this reason, even if the lower limit of the film-forming speed that is cost-effective in the actual manufacturing process is 10 m/min, large equipment with a circumference of the support of 20 m or more is required. On the other hand, if the drying speed is increased in order to shorten the time until peeling, foaming occurs, and if the film is peeled off in a dry, opaque state, residual peeling occurs, which completely impairs the flatness and transparency of the film. Once these problems occur, they cause foaming and peeling one after another, so film formation must be stopped or production speed must be slowed down for cleaning, and even after restarting, these problems are close to the limit. By the way, it takes several hours because it is necessary to gradually increase the operating speed before returning to the normal operating state.

Also, in the method of gluing the cast Dogue by cooling it, it is necessary to evaporate a certain amount of the solvent before peeling off the film. The reason for this is not specifically stated in the patent publication, but in experiments conducted by the present inventors, the self-supporting properties of the peeled film deteriorated even if the film was simply subjected to gluing when most of the solvent remained. It was unsatisfactory. and,
Non-uniform elongation and deformation tended to occur at the peeling section and the subsequent conveyance section, and the film also contracted significantly during the drying process after peeling, making it impossible to obtain a film of good quality. In the method of the patent, as shown in FIG. 25, in order to remove the solvent, hot air 9 supplied from a tube 42 is blown out from a number of pores 43 in the latter half of the band 3 to accelerate drying. This was also done. However, with this method, the evaporation rate of the solvent from the film is very slow, and it takes a long time to remove the solvent to the extent that the above-mentioned problems such as elongation, deformation, and shrinkage do not occur, and the film forming speed is greatly reduced. It was difficult to raise the width.

On the other hand, no technology has been introduced to cellulose triacetate systems to date that allows the dope to be peeled off simply by casting a dope such as cellulose acetate glopionate onto a cooled support and air drying it. The reason for this is that (cellulose) IJ acetate has poor solubility in solvents, and a manufacturing method for high-strength dope suitable for factory production has not been developed, and that low-strength dope has the aforementioned problems and cannot be stably stripped by cooling alone. I'm busy with things I couldn't do.

In addition, increasing the drying rate in the drying step after peeling off the film from the support has a great advantage in increasing the film forming rate.

However, if you try to dry at a high temperature immediately after stripping to increase the drying speed, the surface of the web will have a pitch of 0.3
Wrinkles of about ~4.0 wsr have occurred, or foaming has appeared due to the residual amount of solvent such as methylene chloride (boiling point: 40° C.), making it unusable as a product. Therefore, in the past, after stripping, drying was carried out with care so that the film surface temperature did not exceed the boiling point of the solvent for a while, and, for example, drying was carried out at a high temperature only when the amount of solvent in the web became 30% by weight or less. Drying conditions were set. As a result, not only does drying take a long time, but the burden of managing the drying process also increases.

On the other hand, when these films are coated with photographic emulsion and made into photographic films, cut and cut, and then made into motion picture films by perforating SE-7 olefin holes, damage to the perforations and holes during projection can be avoided. To prevent this, the tear strength properties of the film are important.

An object of the present invention is to shorten the time from casting to stripping and the drying time after stripping to increase the film forming speed and to make the apparatus more compact.

Another object of the present invention is to provide a film forming method that does not cause foaming or peeling residue in the cast film, eliminates wrinkles or foaming in the drying process after peeling, and reduces the incidence of defective products. It is in.

[Failure to solve the problem]

This object of the present invention is achieved by using a dope containing a mixed solvent with a high concentration of cellulose triacetate and a specific composition, and by applying tension in the width direction of the film during drying.

That is, in the present invention, the concentration of the sum of cellulose triacetate and other components that become solid after drying is 18 to 35 parts by weight.
A cellulose triacetate film obtained by casting a dope having a dope of 13% to 25% by weight of a solvent other than methylene chloride in the solvent composition onto a support whose surface temperature is 10°C or less, and cast onto the support. It relates to a method for producing a cellulose triacetate film, which comprises peeling off the film from a support, transporting the film while applying tension in the width direction of the film, and drying the film.

A dope with a high concentration of cellulose triacetate is used, and it is suitable that the total concentration of cellulose triacetate and other components that become solid after drying is 18% by weight or more, preferably 20 to 35% by weight. Other components that become solid after drying include, for example, a plasticizer such as triphenyl phosphate, and various additives that may be added as necessary.

The solvent is a mixed solvent of methylene chloride and another solvent. Other solvents are C1-C4 alcohols such as methanol, n-butanol, etc., poor solvents for cellulose triacetate such as cyclohexane. These may be used alone or in combination of two or more. The mixing ratio is 87 to 75% by weight of methylene chloride, and therefore 13 to 25% by weight of other solvents.

The concentration of cellulose triacetate and the composition of the solvent are determined within the above range so that the dope can be easily produced by the method described below and gluing proceeds as quickly as possible at a predetermined temperature of 10° C. or lower. The gluing temperature of the dope depends on the concentration of cellulose triacetate, solvent composition, etc. A mixed solvent of 92% by weight of methylene chloride and 8% by weight of methanol) and methylene chloride 8
Figure 18 shows the results of measuring the relationship between cellulose triacetate concentration and gluing temperature using a mixed solvent of 3x tS, 7x fik% methanol, and 10% by weight n-butanol. As shown in the figure, the higher the dope roughness and the higher the poor solvent concentration in the composition, the higher the support temperature can be. It is also difficult to make a homogeneous dope. On the other hand, if the poor solvent content is 2 or more, there are disadvantages such as cloudiness in the dope and increased viscosity, which makes transportation difficult.

The present invention was achieved for the first time by developing a technology capable of industrially producing such a high concentration dope.

Such a high-concentration dope can be prepared by, for example, putting cellulose triacetate and the above-mentioned solvent in a pressurized container, sealing it, and heating it under pressure to a temperature above the boiling point of the solvent at normal pressure and within a range where the solvent does not boil. Obtained by stirring.

Cellulose triacetate, a solvent, and other additives that may be added as necessary may be roughly mixed in advance and then placed in a pressurized container, or they may be charged separately.

The type of pressurized container does not matter, as long as it can withstand a predetermined pressure. This pressurized container needs to be able to be heated as well as stirred.

Pressurization may be carried out by injecting an inert gas such as nitrogen gas, or may be carried out only by increasing the vapor pressure of the solvent by heating.

In addition, it is also possible to reduce the gas phase volume within the container by pressurizing some or all of the cellulose triacetate, solvent, and other additives after sealing the pressurized container.

Preferably, the heating is performed from the outside, and for example, a jacket type one is suitable.

In addition, it is also possible to provide heating by providing an external plate heater or the like and connecting it with piping for circulation.

The stirring blade is preferably long enough to reach near the container wall, and it is preferable to provide a scraping blade at the end to renew the liquid film on the container wall.

In addition, other gauges such as pressure gauges and thermometers should be installed as appropriate in the pressurized container.

The above raw materials are placed in a pressurized container and heated under pressure.

The heating temperature is a temperature above the boiling point of the solvent and within a range where the solvent does not boil. This temperature is preferably 60°C or higher, particularly preferably about 80 to 110°C. The pressure is determined so that the solvent does not boil at this set temperature.

After melting, the solution is cooled and then taken out from the container, or otherwise extracted from the container with a pump or the like, cooled with a heat exchanger or the like, and then used for film formation.

In this melting method, by applying pressure, it is possible to heat the material above the boiling point at normal pressure, and boiling is suppressed to prevent an overcondensation state from occurring, thereby preventing the formation of glue. Heating increases solubility and dissolution rate, making it possible to completely dissolve in a short period of time.

The dope casting method may be either the pan P casting method as shown in FIG. 19 or the drum casting method as shown in FIG. , especially the area around the peeled part 2. Since the interface between the support 3 and the P-P 4 is mainly involved in peeling, it is important to sufficiently cool the support surface. The method of cooling is not particularly limited, and any method using a refrigerant or cold air, a method using a heat type, etc. can be used. The cooling temperature is such that the surface temperature of the support is 10°C or less, preferably 5°C or less.

Although it is not necessary to use drying air, it may be used as long as it does not increase the surface temperature of the support.

The temperature of this drying air is preferably as high as possible within a range that does not cause foaming, and is particularly preferably at a temperature of 40°C or higher and lower than 40°C. It is necessary to apply the drying air to the film surface for at least 2 seconds or more, and it is preferable to apply the drying air for 2 seconds or more immediately after casting. Further, the direction in which the drying air is applied to the film surface may be arbitrary, such as vertically or obliquely, but it is preferable that the amount of air is sufficient to effectively dry the film. By using such drying air, the surface of the film is dried before peeling, and the stretching of the film after peeling can be prevented.

The cellulose triacetate film cast onto the support is peeled off from the support and then conveyed while being tensioned in the width direction of the film. To apply tension in the width direction of this film, there is a method of fixing both side edges of the film and transporting the film while maintaining a predetermined interval.
1111 of the film with enough force that the film is not stretched.
There is a method of transporting the 11 parts while being pulled outward in the width direction. That is, in the method of fixing both side edges, tension is applied to the film by preventing free shrinkage of the film. In the method of pulling the .mu.ml edge, free shrinkage of the film is prevented and tension is applied by actively pulling the film.

First, a method for fixing both side edges of the film will be explained. An embodiment of this method is shown in Figures 1 and 2.

Figure 1 shows 50 liters of film peeled off from the support.
11 is a plan view showing a state in which the edges are fixed by the width regulating device 6, and FIG. FIG.

As shown in FIG. 2, cellulose triacetate tape is cast from a casting section 1 onto a support 3, and a film 5 formed thereby is peeled off at a stripping section 2, and a film regulating device 6 It meanders through the drying chamber 8 with its both side edges fixed 1, during which time it is dried by hot air 9 and wound up.

For the width regulating device that fixes both side edges of the film (for example, pin clips as shown in Figure 3 may be used,
Alternatively, it is also possible to use a clip for a tenter used for stretching polycostel films, etc., as shown in FIG. Furthermore, a nip belt system as shown in FIG. 5 can also be used.

For example, the pin clip 10 is attached to a pin stand 1 as shown in FIG.
A large number of pins 12 are implanted in the chain 1, and the pins 12 are attached to a chain (not shown) in a row.

It is preferable that the length of the pin stand 11 is short in order to smooth the movement at the turn of the chain. The pins 12 implanted in the pin stand 11 are preferably arranged in a plurality of rows from the viewpoint of film retention strength, but in reality, two to three rows are sufficient. As a means for biting the pins 12 into the film, a biting roll 13 with grooves cut in accordance with the rows of pins as shown in FIG. 3 may be used, or a brush roll (not shown) may be used. You may. In addition, engineering,
It is also possible to make it bite by blowing air strongly.

When using clips, you can use at least one of those used for tenters. For example, if you attach a number of clips to a chain or the like as shown in FIG. After getting on top, the lever 16 is pushed down and the film 5 is held between the seats 17.

The nip belt method is a method in which the side line portion of the film is held down by a nip belt 18 and a pulley 19, as shown in a plan view in FIG. 5 and in a side sectional view in FIG. 6, for example. As shown in the front view in FIG. 7 and in the side view in FIG. 8, this method uses a large-diameter drum 20 and presses the stations on its circumferential surface with a nip belt 18. In that case, one large-diameter tram may be used, or ovt trams may be used consecutively.

Both side edges of the film fixed by the width regulating device are kept at a predetermined distance during conveyance. This interval may be constant, or may be wider or narrower than when the width regulation started as the width is being transported. The range in which this interval can be widened or narrowed is usually about ±20% of the interval at the start of width regulation. Of course, it is also possible to change this interval in an arbitrary pattern according to the conveyance. Generally, the film shrinks when it dries, so by keeping the gap constant or gradually narrowing it, you can create an appropriate amount of tension in the film.

Width regulation is usually performed immediately after peeling off from the support.

In that case, as shown in FIG. 9, it is also possible to connect directly to the width regulating device 6 without providing a stripping roll.

Furthermore, in case of space limitations, it is also possible to provide the width regulating device 6 at a distance from the support body 3, as shown in FIG. However, in that case, rapid drying must be avoided before controlling the cause.

Next, a method of pulling the 91Q edge will be explained.

One embodiment of this method is shown in FIGS. 11 and 12.

FIG. 11 is a plan view showing a situation in which both side edges of the film 5 peeled off from the support are being pulled by a pulling device 21, and FIG. 12 is a plan view showing a state in which both side edges of the film 5 are being pulled while being dried. FIG.

As shown in FIG. 12, cellulose triacetate dough is cast from the casting section 1 onto the support 3, the film 5 formed thereby is peeled off at the stripping section 2, and the both side edges are removed by the pulling device 21. While being pulled outward in the width direction, the sheet snakes through the drying chamber 8, during which time it is dried by hot air 9 and wound up.

In order to pull the side edges of the film outward in the width direction, it is necessary to grasp and hold both side edges of the film. As the gripping means, the pin clip f10 explained in the method for fixing the side edge portion, the tenter clip 7'14, etc. can be used.

The side edges of the film are pulled by pulling the gripping member. - The weight 1 means of the holding member is not particularly limited, but for example, a spring, a cylinder, a weight 9, etc. can be used.

The traction may be applied directly to the gripping member,
This may be carried out by pulling a chain or the like that drives the gripping member so that it can move in the width direction of the film.

Examples of the acceptance top beak are shown in FIGS. 13 to 17.

The example shown in FIG. 13 has a sliding par 22 at the bottom of the bottle clip 10.
This sliding par 22 is slidably supported by a ring 23, and this ring 23 is connected to a drive chain 24.
The chain 24 is fixed to the pink I
It is designed to run J, y f 10. A chain 25 is made to run along the outside of the bottle clip, and a spring 26 is used to connect the chain 25 with the bottle clip, so that the contracting force of the spring 26 can appropriately pull the bottle clip flO'. The rocket of the chain 24 and the rocket of the chain 25 (both not shown) are attached to the same shaft.
The lock cutter of the chain 24 can be engaged with the chain 24 for this purpose and can be slid in the axial direction. On the other hand, chain 25
The Suguro Kutha is fixed to the shaft.

The example shown in FIG. 14 is an example in which the spring 26 in the traction mechanism shown in FIG. 13 is replaced by an air cylinder 27.

In the example shown in FIG. 15, a goal roller 28 is attached to the bottom KA of a pin clip 7'lO, so that the bin clip 10 can run freely on the base plate 29, and a double layer on the side surface that slides and expands and contracts. '#30 is installed. This double U-shaped outer tube is attached to a fixed chain 25, and the pin clip f10 is driven and driven by this chain 25. A rope f31 is attached to the inner pipe of the second shift and ρ, and a weight 32 is suspended from the end of this rope 31, so that the weight of the weight 932 can pull the binkri f10. .

In the example shown in FIG. 16, a slide bearing 33 is attached to the bottom of the bottle clip 7°10 so that the bottle clip 10 can freely run on a slide base 34. Also, the bin clip arm 3 is attached to the bin stand 11 of the pin clip 7'IO.
A fixed arm 36 is fixed to the slide table 34. These pin clip arms 35 and fixed arms 36 are connected to the integral arm 3.
7 and is rotatably connected to form a link mechanism.

The integral arm 37 is formed into a substantially “<” shape with its substantially central portion bent, and its substantially central portion is rotatably connected to the fixed arm 36, and one end thereof is connected to the big ag arm 35. Rotatably connected. And integral arm 3
A weight 32 is attached to the other end of 7, and this weight 32
The integral arm 37 rotates around the fixed arm 36 due to the weight of
The arm 35 is configured to be pulled outwardly and pull the pin clip flO.

Further, a fixed chain 38 is provided below the slide table 34.
is attached to the chain 38, and is configured so that the chain 38 and f10 travel simultaneously as the chain 38 is driven.

The integral arm 37 is separable and the weight 32 is movable, so that the weight 32 automatically moves the web 11 when turning.
1I (inner 1'!II), the pin clip 10 can be retracted even if the pin of the pin clip 10 is facing downward.

In the example shown in FIG. 17, the pin clip arm 35, integral arm 37, and bowl 32 are connected to the spring 3 on the traction machine side shown in FIG.
This is an example in which 9 is substituted. In this example, the fixed arm 36 is bent toward the pin clip 10 at approximately the center to form a bent portion 40, and the bent portion 40 and the pin clip 110 are connected by a spring 39. The contracting force of the spring 39 is used to appropriately pull the pink flo.

In these examples, N1 variations are possible.

For example, in the examples shown in Figures 13, 14, or 17, the repulsive force of a spring or air cylinder may be used, or as shown in Figure 15, a double pipe may be used to connect the chain into one unit. It's okay. Further, the running system of the binder and the rig may also be a sol roller system as shown in FIG. 15. vice versa,
In the example shown in FIG. 15, it is also possible to change the driving method or traveling method of the pin clip to the example shown in FIG. 13.

Further, in these examples, it is also possible to replace the pin clip with a tenter rig as shown in FIG.

Although it is necessary to grip and hold the film at both side edges, it is also possible to pull the film from only one side edge and simply fix the position of the other side edge.

The number of traction devices may be one, or two or more may be connected in series.

The sheep attraction is determined to suit the purpose. The width of the film may be almost constant from the start of traction, or may be expanded or narrowed within a range of about ±20% from the start of traction as the film is conveyed.

The traction force may be the same throughout the travel route, or may be changed midway along the travel route if necessary.

Traction is usually performed immediately after peeling off the support.

In that case, as in the case of the width regulating device shown in FIG. 9, it is also possible to connect directly to the traction device 21 without providing a stripping roll.

After stripping, if the amount of solvent in the web is up to 50% by weight, 61/Ayota 2~40//1m'', and from 50% by weight to 30 layers, 1511/8Z~100.9/Tomo2 Preferably traction.

Also, due to space constraints, the traction device flit21 is attached to the support body 3 as in the case of the width regulating device shown in FIG.
It may be provided separately from the However, in that case, rapid drying must be allowed to occur before towing.

The drying means is not limited, and for example, hot air, infrared rays, etc. may be used. The drying temperature may be set to be higher than the boiling point of the solvent immediately after width regulation or traction, and the drying temperature can be heated to around 100° C. at once. To speed up drying, it is best to blow drying air onto both sides of the film, and the angle of the air should also be perpendicular to the film surface. Drying temperature/IP turn can also be set freely,
For example, the temperature is often set divided into 100° C. for the first half and 120° C. for the second half.

[For production]

In the method of the present invention, peeling off due to the adhesion between the support and the film is not rate-limiting. The rate-determining condition in the present invention is to give the film enough strength to overcome the influence of its own weight and its inertia when peeled off from the support, and that force is usually 17% compared to the adhesive force.
10 or less.

This makes it possible to significantly speed up the process. As a result, for example, if equipment with an effective length of 20 m was conventionally used, it is now sufficient to use equipment with an effective length of 2 to 3 m to maintain the same speed, significantly reducing equipment costs and running costs. I can do it.

Next, in the method of the present invention, since the undried dough is not heated to a high temperature, foaming due to boiling of the solvent does not occur at all. In the conventional method, foaming occurs when the temperature of the undried film exceeds the boiling point of methylene chloride, which is the main solvent, at 40°C.

In addition, the method of the present invention does not use the conventional solidification of the dope by drying as the main mechanism, but uses the dulceting of the dope under specific conditions at low temperatures as the main mechanism for stripping.
As long as the surface temperature of the support is sufficiently low, no peeling remains. As a result of the above, there is an advantage that the speed can be freely increased or decreased without considering the problem of remaining on the support, which has been the biggest problem in conventional cellulose triacetate film formation.

The main reason why wrinkles appear on the surface of a cellulose triacetate film during the drying process is thought to be due to uneven shrinkage of the film during the evaporation process of the solvent. Therefore, if high temperature drying is performed rapidly in a state where the solvent content is high, the non-uniformity of the solvent distribution becomes large, non-uniform shrinkage occurs, and the surface quality deteriorates. This non-uniformity in solvent distribution is inherent during drying and cannot be removed. Measures can only be taken against uneven shrinkage.

This non-uniform contraction occurs in all directions, but conveyance tension is acting in the conveyance direction, and the shrinkage is
A sufficient suppressive effect is produced.

Therefore, by using a conveyance means that can suppress this shrinkage in the width direction perpendicular to the conveyance direction where no suppressing force is applied, it is possible to avoid deterioration of the surface quality.
High temperature drying is possible.

In conventional conveyance using rolls, the frictional force between the rolls and the film can act as a force to suppress this uneven shrinkage.
This frictional force is extremely small compared to the shrinkage force, and has little effect on preventing deterioration of surface properties. Also, rapid shrinkage on the roll may cause scratches on the surface of the film.

One method of transporting the film is to blow air out of a nozzle, float the film using the dynamic or static pressure of the air, and transport the film in a non-contact manner. This method is normally used in the drying process after coating, but even if it is used immediately after stripping the film, the ability to suppress shrinkage in the width direction of the film will be insufficient even if the scratches mentioned above can be prevented. Similarly, there is no effect of preventing deterioration of surface properties.

Therefore, it is necessary to employ a transportation method other than the above.

In other words, so that the film cannot freely shrink in the width direction,
By drying while transporting the film with both sides fixed or with the film pulled in the width direction,
Deterioration of surface quality can be prevented.

In addition, the method of regulating the width and the method of pulling in the width direction also have another important effect. If the solvent content after stripping is 50% or more by weight of the dry film, foaming will occur if the film surface temperature exceeds the boiling point of the solvent, and the film cannot be used as a product. Conventionally, this has been prevented by slowing down the drying speed so that the film surface temperature is below the boiling point of the solvent. However, after drying,
By using a conveying method that restricts the width or pulls the membrane in the width direction, it has become possible to dry the membrane without foaming even if the membrane surface temperature exceeds the boiling point of the solvent. This is done by fixing or pulling the film width in the width direction so that it cannot freely shrink, resulting in strong tension in the film width direction, increasing the internal pressure within the film and raising the boiling point. It is thought that there is.

〔Example〕

Example 1 Cellulose triacetate 25% by weight, triphenyl phosphate 3% by weight, methylene chloride 60% by weight+i
Prepare a dope consisting of H and 12 layers of methanol,
This was cast in a Citram casting machine using a conventional method. The solvent content of the film in the peeled part was 65% by weight.

Both edges of this film were fixed with pins as shown in Figure 6 and dried with dry air at 105°C while maintaining the same distance between them, and the change in solvent content over time was measured.
The results shown in the white circles in the figure were obtained. This film had no foaming at all, and the surface measured with a three-dimensional roughness meter had no irregularities as shown in FIG. 22.

Cut this film into 40 m x 80 pieces, make a 5 m long incision in the center of the width along the long side, and cut into 10 pieces.
When the tear strength was measured with a load of 0g, it was 8O-x.
oo, 9/120μ.

Example 2 A dope with the same composition as in Example 1 was used and was pulled in the width direction using a device equipped with a traction T9 structure as shown in FIG. 16.
The sample was dried with dry air at 5° C., and the change in solvent content over time was measured, and the result was approximately the same as that shown in FIG. 21 of Example 1. Oh yeah
It is the same as in Example 1, with no foaming and no unevenness.
Moreover, the tear strength was also approximately the same as in Example 1.

Comparative Example Next, for comparison, the same film was dried with dry air at 65°C without width regulation or traction, and the change in solvent content over time was measured, as shown by the black circles in Figure 21. The results were obtained. This film was foamed, and the surface measured with a three-dimensional roughness meter was also uneven as shown in FIG. 23. Moreover, when the tear strength of this film was measured under the same conditions as in the example, it was 40 to 50 I! /120μ.

〔Effect of the invention〕

In the method of the present invention, the base stripped by cooling drum casting has a high volatile content, has no stress history on the support, and can be freely shrunk by drying. This can then be dried while controlling shrinkage. For this reason, while preventing the occurrence of wrinkles due to free contraction,
It is possible to control the shrinkage rate and stress over a wide range, and as a result, it is possible to easily obtain the flatness and strength required for photographic films.

In addition, since the time during casting and subsequent drying is shortened, the overall film forming speed can be dramatically increased, and it is possible to form dung and dirt. Further, the film is free from foaming and no peeling remains 9, thereby reducing the incidence of defective products. Furthermore, sufficient tear strength necessary for a photographic film can be obtained.

[Brief explanation of drawings]

FIG. 1 is a plan view showing a state in which the film peeled from the support is transported with both side edges fixed, and FIG. 2 is a plan view showing the film peeled from the support and dried by the method of the present invention. Fig. 3 is an inclined view showing the state in which both edges of the film are fixed and conveyed, and Fig. 4 is an inclined view showing the state in which the film is transported with both edges fixed. Fig. 5 is a side view showing another example of the tool. Fig. 5 is a plan view of an example in which the side edges are nipped and fixed with a belt, and Fig. 6 is a side sectional view thereof. Fig. 7 Secure it with a belt.
FIG. 8 is a front view of another example, and FIG. 8 is a side view thereof. Fig. 9 is a side view of an example in which the width regulating device is directly connected to the support without providing a stripping roll, and Fig. 10 is a side view of an example in which the width regulating device is separated from the support. . FIG. 11 is a plan view showing the state in which the film peeled off from the support is being transported while being pulled on both side edges;
The figure shows the state in which the film peeled off from the support is dried by the method of the present invention (I'lti side view). Figures 13 to 17 are side views showing examples of the traction skewer structure. Figure 18 shows the results of measuring the relationship between cellulose triacetate concentration and gelation temperature for dopes using two mixed solvents: methylene chloride-methanol or methylene chloride-methanol-n-butanol. 20 is a schematic view of a band casting device and FIG. 20 is a diagram showing an outline of a drum casting device. FIG. 21 shows the change over time in the solvent content of a film obtained by carrying out the method of the present invention, compared to that of a conventional method. Figure 22 is a cross-sectional view showing the planar state of the film obtained by drying the method of the present invention and Figure 23 by the conventional method. Figure 24 is a drum casting apparatus. FIG. 25 is a side view showing the conventional cooling stripping method of the band casting apparatus. 1... Casting section 2... Stripping section 3...・Support 5
... Film 6 ... Control device 8 ... Drying room 9 ... Hot air 10 ... Pink clip 14 ... Rizzo for tenter 18 ... Nip belt 21 ...
Traction device 26...Paper 27...Air cylinder 32...Weight Patent applicant: Fuji Photo Film Co., Ltd. Patent attorney: 1) Masahiro Naka, Figure 1, Figure 2, Figure 3, Figure 5, Figure 6 Figure 7th ry! i Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 Figure 13 Figure 18 Figure 20 Figure 21 @ Figure 22 Figure 23 Figure 24

Claims (4)

[Claims] (1) A dope with a concentration of the sum of cellulose triacetate and other components that become solid after drying is 18 to 35% by weight, and a proportion of solvent other than methylene chloride in the solvent composition is 13 to 25% by weight, at a surface temperature of Cellulose is cast on a support at 10° C. or lower, and after the cellulose triacetate film cast on the support is peeled from the support, the film is conveyed while applying tension in the width direction and dried. Method for manufacturing triacetate film (2) The method for producing a cellulose triacetate film according to claim 1, which provides tension in the width direction of the film by fixing both side edges of the cellulose triacetate film and maintaining a predetermined distance between them. (3) The cellulose triacetate film according to claim 1, in which tension is applied in the width direction of the film by pulling the side edges of the cellulose triacetate film outward in the width direction with a force that does not stretch the film. Production method (4) The method for producing a cellulose triacetate film according to claim 1, 2 or 3, in which the dope is cast onto the support and then drying air is applied to the surface of the cellulose triacetate film on the support.