JPH06278149A - Manufacture of cellulose triacetate film - Google Patents

Abstract

PURPOSE:To enable a cellulose triacetate film which is excellent in a planar property even though dried quickly at high temperature in its manufacture by a solution film-forming method. CONSTITUTION:A cellulose triacetate film stripped off from a flow-extending part 10 is dried with drying parts 20, 30. The cellulose acetate film dried with the drying parts 20, 30 is sent to a planar property improving part 50. It is carried while being wound around a heating roller group 54 in a heating chamber 51 of the planar property-improving part 50, and unevenness generated with the drying parts 20, 30 is leveled. Just thereafter, it is solidified under a planar state as it is while being wound around a cooling roller group 56.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing a cellulose triacetate film having good flatness.

[0002]

2. Description of the Related Art One of the methods for producing a cellulose triacetate film is a solution casting method in which a dope is cast on a band or a drum and then stripped and dried.

Conventionally, as a drying method in this solution film-forming method, for example, as shown in FIG. 2, a cellulose triacetate film 73 peeled from a casting surface (drum surface) 71 is provided in a drying chamber 72. In addition, there is a method of drying with hot air a, infrared rays, etc. while it is passed over a large number of rollers 74 and moved between the large number of rollers 74 (referred to as a roller conveyance method) (US Pat. No. 2,319,053 specification, etc.). ).

There is also a method in which both side edges of the cellulose triacetate film peeled from the casting surface are dried while being conveyed without being stretched while being held by tenter clips or the like (JP-A-62-46625). , JP-A-62-4
6626 publication). This method is effective when the residual solvent of the cellulose triacetate film peeled off from the casting surface is very large and the surface of the cellulose triacetate film is damaged by contact with the roller surface when the method is carried out by the roller transport method.

By the way, the solution film forming method has a big problem that the film forming speed is slow, and it has been an industrially important issue to increase the drying speed also in the drying step. Therefore, it is preferable to peel off the cellulose triacetate film from the casting surface as soon as possible, and dry at a high temperature from both sides of the cellulose triacetate film,
A gelling agent therefor, for example, a high-boiling solvent such as butanol is included in the dope (US Pat. No. 2,607,704, US Pat. No. 2,739,069, etc.), and a method of increasing the drying temperature is also used. Was proposed.

[0006]

However, in the above-mentioned conventional method, the flatness of the cellulose triacetate film is poor. That is, when the cellulose triacetate film is conveyed in the drying step, continuous wrinkles (hereinafter, referred to as streak burrs) are generated in the conveying direction, and the streak burrs frequently occur as the temperature becomes high. For example, the pitch is 30 to 50 mm, the height of unevenness during transportation is 5 to 6 mm (0.5 to 1.0 m when stationary and no tension).
m) streaks were occurring.

The cause of this streaking is that, as a result of the research conducted by the inventors of the present invention, the elastic modulus of the cellulose triacetate film is lowered by high temperature drying, and the film is easily stretched in the direction due to the conveying tension acting in the conveying direction. At this time, it was found that a compressive force acts in the width direction of the cellulose triacetate film, so that it buckles and deforms, and as a result, streaks occur.

[0008] When the cellulose triacetate film is used as a support for a photographic film or the like, the stripes cause uneven thickness of the emulsion layer.

The present invention solves the above problems and provides a method for producing a cellulose triacetate film having good flatness without causing streaks even when the drying speed is increased by high temperature drying to form a high speed film. With the goal. Another object of the present invention is to make it possible to produce a photographic film capable of forming an emulsion layer having a uniform thickness.

[0010]

The present invention has been made to achieve the above object, and a method for producing a cellulose triacetate film of the present invention comprises casting a dope for a cellulose triacetate film on a band or a drum. Casting step, a drying step of drying the cellulose triacetate film stripped from the band or drum of this casting step, and a flatness improving step of flattening the irregularities of the cellulose triacetate film dried in this drying step. The step of improving the flatness is a roller heating step in which the cellulose triacetate film that has undergone the drying step is heated while being heated by a heating roller to be flattened, and immediately after this roller heating step is cooled while being conveyed by a cooling roller. And a roller cooling step for solidifying the cellulose triacetate film. It is constructed the door as a feature.

The method for producing a cellulose triacetate film of the present invention comprises a casting step of casting a dope for a cellulose triacetate film on a band or a drum, and a cellulose triacetate stripped from the band or the drum of this casting step. It has a drying step of drying the film, and a flatness improving step of flattening the unevenness of the cellulose triacetate film dried in this drying step, the flatness improving step is a far infrared ray of the cellulose triacetate film that has undergone the drying step. A roller heating step in which the roller is heated and flattened while being heated by a heater and heating roller,
Immediately after this roller heating step, a roller cooling step of cooling and transporting with a cooling roller to solidify the cellulose triacetate film is provided.

To heat and cool the cellulose triacetate film in the roller heating step and the cooling step of the flatness improving step, a plurality of heating roller groups and cooling roller groups are respectively provided, and after heating by the heating roller groups, cooling roller groups are provided. Even if it is cooled with, even if one heating roller and one cooling roller each having a large diameter are provided, and one heating roller is used for heating and then one cooling roller is used, the half surface of the one roller with a large diameter is heated. Alternatively, the other half surface may be used as a cooling portion, that is, one roller may be used as both a heating roller and a cooling roller, and the heating portion of one half surface may be heated and then the cooling portion of the other half surface may be cooled. However, a method using a roller group is preferable because scratches due to shrinkage are less likely to occur.

When the roller group is used, the number of the heating roller group and the cooling roller group is appropriately increased or decreased depending on the film forming speed, the roller temperature, the film thickness, and the residual solvent amount, but it is usually between 10 and 30. The diameter of the roller is preferably 5 to 20 cm, more preferably 7 to 15 cm.

The rollers are preferably arranged so as to be adjacent to each other in substantially the same plane or in the same two planes as the drying zone so that the roller path distance is sufficiently small. This is because if the distance of the roller path becomes long, streaks easily occur. That is, as a result of the research conducted by the present inventors, the occurrence of streaks is not directly related to the diameter or material of the roller, and the roller path distance, that is, until the film separated from one roller contacts the next roller. It turns out to be related to distance. The roller path distance changes depending on the rigidity of the conveyed cellulose triacetate film,
It is preferably 3 to 30 cm, more preferably 4 to 15 cm.

The temperature of the heating roller may be a temperature at which the cellulose triacetate film is sufficiently softened, preferably 100 to 190 ° C, more preferably 120 to 170 ° C.
If the temperature of the heating roller is too high, the plasticizer in the film is leached out, which is not preferable. To heat the heating roller,
The heating roller itself may be provided with a built-in heat source such as a heater, heated by hot air, or heated by an external heat source such as a far infrared heater. Further, the built-in heat source and hot air may be combined, the built-in heat source and external heat source may be combined, the hot air and external heat source may be combined, or the built-in heat source, external heat source, and hot air may be combined.

The temperature of the cooling roller may be any temperature at which the rigidity of the cellulose triacetate film is sufficiently obtained, preferably 10 to 95 ° C, more preferably 20 to 80 ° C. To maintain the cooling roller at a predetermined temperature, a cooling roller using warm air or a refrigerant having a predetermined temperature is used.

The interval between the end of heating by the heating roller and the cooling by the cooling roller is the interval at which the cellulose triacetate film having the unevenness flattened by the heating roller is cooled by the cooling roller while maintaining its flat state. It is set appropriately depending on the rigidity of the triacetate film.

[0018]

In the method for producing a cellulose triacetate film of the present invention, in the drying step, the cellulose triacetate film in which the flatness is deteriorated due to the buckling deformation in the width direction due to the conveying tension and the occurrence of streaks is wound around the heating roller. At the same time, it is softened by transportation and flattened by eliminating streaks. Immediately, it is rolled by a cooling roller and transported to be solidified and straightened.

The method for producing the cellulose triacetate film of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic view of a manufacturing apparatus for carrying out the method for manufacturing a cellulose triacetate film.

In FIG. 1, reference numeral 10 is a casting portion for casting a cellulose triacetate film dope, and reference numerals 20 and 30 are first drying portions for sequentially drying the cellulose triacetate film 40 peeled from the casting portion 10. And a second drying section, and a reference numeral 50 is a flatness improving section for eliminating streaking of the cellulose triacetate film 40 sent from the second drying section 30. An undercoat coating section 60 is provided between the first drying section 20 and the second drying section 30.

The casting part 10 comprises a band 11 cooled to a predetermined temperature and a casting port 12 provided on the upper part thereof. Also, the first and second drying sections 20 and 30, respectively,
Hot air supply ports 21 and 31 for supplying the hot air a to the room are provided, and a plurality of rollers 22 and 32 for conveying the cellulose triacetate film 40 are provided.

The flatness improving section 50 is provided with a heating chamber 51 and a cooling chamber 52 adjacent to each other, and a large number of heating rollers 53 are arranged in the heating chamber 51 so as to be adjacent to each other on a substantially same plane. group
54, a cooling roller group 56 in which cooling rollers 55 are arranged adjacent to each other on the substantially same plane in the cooling chamber 52 is a heating roller group 54.
Are arranged in succession. Further, the heating chamber 51 is provided with a hot air supply port 57, and the hot air b is supplied from the hot air supply port 57 into the room. The cooling chamber 52 is provided with a cooling air supply port 58. The cooling air supply port 58 supplies the cooling air c into the room.

In order to manufacture a cellulose triacetate film with the above-described manufacturing apparatus, first, a dope having a predetermined composition is cast from the casting port 12 to the band 11 and dried under a temperature condition in which the cast dope does not foam. Carry while carrying. Then, when the self-retaining property is exhibited to some extent, it is peeled off from the band 11, then sent to the first drying section 20, and is fed by the rollers 22 while feeding the hot air a from the hot air supply port 21, and dried until the undercoating is possible. The thus-dried cellulose triacetate film 40 is sent to the undercoat application section 60, and the undercoat agent for a photographic light-sensitive material is applied. Then, apply the undercoated cellulose triacetate film 40 to the second drying section.
It is sent to 30 and dried as in the first drying chamber 20.

Next, a cellulose triacetate film
40 is sent to the flatness improving section 50, first, by blowing hot air in the heating chamber 51 and carrying it while being wound by the heating roller group 54, the surface is flattened by softening and removing the generated burrs, then In the cooling chamber 52, while cooling air is blown, the cooling roller group 56 solidifies the flat state. Therefore, the cellulose triacetate film 40 discharged from the cooling chamber 52 is wound up in a good flat state with no surface irregularities.

FIG. 2 is a schematic view of another example in which the flatness improving portion of the manufacturing apparatus for carrying out the method for manufacturing a cellulose triacetate film is changed.

In this manufacturing apparatus, a far-infrared heater 59 is arranged in the heating chamber 51 so as to face the heating roller 53, and the other structure is the same as that of the manufacturing apparatus of FIG. In this manufacturing apparatus, in the heating chamber 51, the far infrared heater 59
Thus, the heating roller 53 and the cellulose triacetate film are heated. The heating with hot air may or may not be performed at the same time.

[0028]

【Example】

Example 1 Cellulose triacetate 21% by weight, triphenyl phosphate 3% by weight, methylene chloride 65
% By weight, 7% by weight of methanol, and 4% by weight of butanol
Was prepared and cast by a band casting machine as shown in FIG. During the drying process, an undercoat for a photographic emulsion was applied using an undercoat machine to produce a cellulose triacetate film having a thickness of 120 μm. The drying temperature is 20 in the first drying chamber.
Was 110 ° C., the second drying chamber 30 was 120 ° C., the heating chamber 51 of the flatness improving section 50 was 130 ° C., and the cooling chamber 52 was 50 ° C.

The radius of the heating roller 53 is 5 cm and is 12 cm.
20 pieces are arranged at a pitch of, and the radius of the cooling roller 55 is 5 cm.
20 pieces were arranged at a pitch of 12 cm, and the conveyance speed was 60 cm / sec.

Then, the obtained cellulose triacetate film was coated with a photographic emulsion to evaluate the coating unevenness.
As the evaluation method, after development, color unevenness was visually determined using transmitted light.

As a result, despite being dried at high temperature,
The flatness of the film was good, and there was almost no coating unevenness of the photographic emulsion.

[Embodiment 2] The flatness improving step in Embodiment 1 was changed to a heating method using a far infrared heater shown in FIG. The same dope for cellulose triacetate film as in Example 1 was used, and the thickness was 120 under the same conditions as in Example 1.
A μm cellulose triacetate film was produced.
However, the heating chamber 51 in the flatness improving step was 100 ° C., and the temperature of the cellulose triacetate film heated by the far infrared heater was 150 ° C.

Then, the obtained cellulose triacetate film was coated with a photographic emulsion in the same manner as in Example 1 to evaluate the coating unevenness.

As a result, despite the high temperature drying,
The flatness of the film was good, and there was almost no coating unevenness of the photographic emulsion.

Comparative Example Using the same dope as in Example, the same dope as in Example was cast-cast under the same conditions as in Example, and the undercoat coating for photography and the drying were performed. However, the cellulose triacetate film exiting the second drying chamber 30 was wound up as it was without being sent to the flatness improving section 50.

Then, the obtained cellulose triacetate film was coated with a photographic emulsion in the same manner as in Examples to evaluate the coating unevenness.

As a result, since the film was dried at a high temperature, the flatness of the film was poor and the coating unevenness of the photographic emulsion was noticeable.

[0038]

INDUSTRIAL APPLICABILITY According to the present invention, since the cellulose triacetate film can be dried at high temperature and high speed while keeping the flatness thereof excellent, the production rate of the cellulose triacetate film can be remarkably increased. As a result, a good quality photographic film with a uniform emulsion layer formed,
It can be manufactured at low cost.

[Brief description of drawings]

FIG. 1 is a schematic view of a manufacturing apparatus for carrying out the method for manufacturing a cellulose triacetate film of the present invention.

FIG. 2 is a schematic view of a flatness improving section using a far infrared heater of a manufacturing apparatus for carrying out the method for manufacturing a cellulose triacetate film of the present invention.

FIG. 3 is a schematic view of a manufacturing apparatus for carrying out a conventional method for manufacturing a cellulose triacetate film.

[Explanation of symbols]

 10 ... Casting section 20 ... First drying section 30 ... Second drying section 40 ... Cellulose triate film 50 ... Flatness improving section 51 ... Heating chamber 52 ... Cooling chamber 53 ... Heating roller 54 ... Heating roller group 55 ... Cooling roller 56 ... Cooling roller group 59 ... Far infrared heater

Claims (2)

[Claims] 1. A casting step of casting a dope for a cellulose triacetate film on a band or a drum, a drying step of drying the cellulose triacetate film peeled from the band or the drum of the casting step, and a drying step. And a flatness improving step for flattening the unevenness of the dried cellulose triacetate film, wherein the flatness improving step is carried out by heating the cellulose triacetate film which has undergone the drying step with a heating roller and heating the roller to flatten it. A method for producing a cellulose triacetate film, which comprises a step and a roller cooling step in which the cellulose triacetate film is solidified by being conveyed while being cooled by a cooling roller immediately after the roller heating step. 2. A casting step of casting a dope for cellulose triacetate film on a band or a drum, a drying step of drying the cellulose triacetate film peeled from the band or the drum of the casting step, and a drying step. It has a flatness improving step of flattening the unevenness of the dried cellulose triacetate film, and the flatness improving step is carried out while heating the cellulose triacetate film which has undergone the drying step with a far-infrared heater and a heating roller to flatten it. And a roller cooling step of immediately after the roller heating step, the roller cooling step of cooling and transporting with a cooling roller to solidify the cellulose triacetate film.