JPH06134933A - Cellulose triacetate laminated film and production thereof - Google Patents

Abstract

PURPOSE:To easily peel a cellulose triacetate laminated film from a casting support while ensuring a sufficient wet heat resistance in producing the laminated film. CONSTITUTION:Pumps 33, 34 are driven to send a dope 11 for a cotton film and a dope 21 for a pulp film to a co-casting die 30. The sent-in dopes 11, 21 are cast on a band 37 as a two-layered structure wherein the dope 11 for the cotton film is positioned on a lower side and the dope 21 for the pulp film is positioned on an upper side. Therefore, only the dope 11 for the cotton film comes into contact with the band 37 and the dope 21 for the pulp film becomes a state not coming into contact with the band 37. The formed laminated sheet is dried by hot air (a) while fed in this state to be peeled off from the band 37 by a scraping roll 39.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cellulose triacetate laminated film useful as a support for a photosensitive material and a method for producing the same, and more specifically, cellulose triacetate excellent in peelability from a cast support and resistance to moist heat. The present invention relates to a laminated film and a manufacturing method thereof.

[0002]

2. Description of the Related Art A cellulose triacetate laminated film is produced by preparing a dope prepared by mixing cellulose triacetate and a plasticizer in a mixed solvent of 90 to 95% by weight of methylene chloride and 5 to 10% by weight of a lower alcohol. The dope is cast on a casting support to form a web. Then, after drying and solidifying the web, the produced film is peeled from the casting support.

However, since the above-mentioned dope solidifies slowly with evaporation, it takes a long time to peel the web from the support, resulting in low productivity.

Therefore, conventionally, various techniques have been proposed for promoting the solidification of the dope. For example, a technique of adding a gelation accelerator in the dope (Japanese Patent Publication No. 459074),
Techniques for increasing the amount of alcohol blended in the dope to 13 to 30% by weight (JP-A-54-48862) and techniques for adding a peeling accelerator to the dope (US Pat. No. 4,600,552) have been proposed. .

[0005]

However, the above-mentioned conventional techniques have problems, respectively. That is, in the technique of adding a gelling accelerator, when a gelling accelerator having a high boiling point is used, it is considered that evaporation is difficult even during the drying and curing of the web.
Therefore, it cannot be said that there is no possibility that the gelling accelerator remains in the film. As a result, when the film is used as a protective film for a polarizing plate, there is a possibility that it may cause a problem in terms of odor.

Further, in the technique of increasing the amount of alcohol blended, if the alcohol content in the dope is large, even if various blending components (for example, methylene chloride) are recovered from the used dope and are reused, they are isolated. -It is uneconomical because purification is difficult and only a small amount of pure material is recovered. In addition, alcohols are often hygroscopic, and therefore the use of large amounts of alcohol can lead to unwanted water incorporation into the dope. This causes deterioration of film quality.

Further, in the technique of adding a peeling accelerator, in a subsequent step, scratches due to slippage during transportation, defective bonding with another film due to an adhesive, and the like were derived.

The present invention solves the above-mentioned problems, has a good releasability without adding a special additive and the like, and
An object of the present invention is to provide a cellulose triacetate laminated film which retains resistance to moist heat and a method for producing the same.

[0009]

[Means for Solving the Problems] The inventors of the present invention have conducted extensive studies in order to achieve the above object, and cellulose triacetate prepared from cotton as a raw material has excellent releasability, and cellulose prepared from pulp as a raw material. It was found that triacetate has excellent resistance to heat and humidity. Then, further research was conducted, and it was found that when these films are combined, good peeling properties are maintained while maintaining good properties, and the present invention was completed.

That is, the cellulose triacetate laminated film of the present invention is characterized by having a cellulose triacetate film prepared from cotton and a cellulose triacetate film prepared from pulp.

In the method for producing a cellulose triacetate laminated film of the present invention, a dope containing cellulose triacetate prepared from cotton and a dope containing cellulose triacetate prepared from pulp are cast with a dope containing cellulose triacetate prepared from cotton. The casting is performed so as to be in direct contact with the supporting body.

The cellulose triacetate film prepared from cotton (hereinafter referred to as cotton film) improves the releasability from the casting support, and is formed mainly from cellulose triacetate prepared from cotton. It is a film. Cotton is not particularly limited, and various cotton can be used, but cellulose triacetate prepared from cotton has an average degree of polymerization of 300 to 400 and an acetylation degree of 58.0 to.
It preferably has a glass transition point of 62.5 and a glass transition point of 115 to 125 ° C. The content of cellulose triacetate prepared from cotton is 70
% Or more is preferable. Such cellulose triacetate is prepared by a conventionally known method, for example, a solution uniform acetylation method and a fibrous acetylation method.

The cotton film usually contains a plasticizer, and examples of the plasticizer include triphenyl phosphate, tricresyl phosphate, triethyl phosphate, biphenyl diphenyl phosphate as a phosphate ester type, and the like. It is possible to use dimethyl phthalate, diethyl phthalate, dimethoxyethyl phthalate, etc. as the phthalic acid ester type, ethyl phthalyl ethyl glycolate as the glycolic acid ester type, other toluene sulfonamide type, triacetin, etc. alone or in combination. . The plasticizer content is preferably 5 to 30% by weight with respect to cellulose acetate. Further, various additives such as UV absorbers, dyes, and slip agents can be added depending on the application.

The thickness of the cotton film depends on the total thickness of the laminated film, but is 0.5 μm in order to ensure sufficient peelability.
Since it is preferably m or more, and the raw material cost becomes high and the wet heat resistance becomes poor, it is preferably within 50% of the total thickness of the laminated film.

The cotton film is formed by casting a dope containing cellulose triacetate prepared from cotton (hereinafter referred to as a dope for cotton film). This cotton film dope is obtained by dissolving the above-mentioned cotton triacetate prepared from cotton in a solvent. This solvent is preferably a mixed solvent of methylene chloride and a lower alcohol, and examples of the lower alcohol include methanol and ethanol.

A film made of cellulose triacetate prepared from pulp (hereinafter referred to as pulp film) is
It is a film that has good resistance to moist heat and is formed mainly from cellulose triacetate prepared from pulp. The pulp is not particularly limited, and various pulps can be used, but cellulose triacetate prepared from the pulp has an average degree of polymerization of 200 to 350 and an acetylation degree of 58.0 to 6
2.5, glass transition point of 115 to 125 ° C. is preferable. The content of cellulose triacetate prepared from pulp,
70% or more is preferable. Such cellulose triacetate is prepared by a conventionally known method, for example, a solution uniform acetylation method and a fibrous acetylation method.

Like the cotton film, the pulp film usually contains a plasticizer, and similarly various additives can be added depending on the intended use. Although the thickness of the pulp film depends on the total thickness of the laminated film, it is preferably 50% or more of the total thickness in order to secure sufficient wet heat resistance.

The pulp film is formed by casting a dope containing cellulose triacetate prepared from pulp (hereinafter referred to as a pulp film dope). This dope for pulp film is obtained by dissolving the cellulose triacetate prepared from the above-mentioned pulp in a solvent. This solvent is similar to the dope for cotton film.

The dope for the cotton film and the dope for the pulp film may have substantially the same viscosity, but it is preferable that the dope for the cotton film has a high viscosity and the dope for the pulp has a low viscosity. The viscosity is 700 cp and the viscosity of the pulp dope is 350 cp. By setting the viscosity in such a relationship, the flatness of the film surface can be improved without delaying the drying of the film on the casting support.

The cellulose triacetate laminated film of the present invention has the above-mentioned cotton film and pulp film, but if necessary, an antistatic layer, a slipping layer for improving running property in a camera, and prevention of scratches. Can be laminated with a protective layer, an antihalation layer, etc.
It is also possible to stack cotton films on both sides of the pulp film, which can prevent migration of the melt in the bulk.

In order to produce a cellulose triacetate laminated film comprising a cotton film and a pulp film as described above, the cotton film dope and the pulp film dope are brought into direct contact with the casting support. Cast. That is, the cotton film dope may be directly cast on the casting support, and the pulp film dope may be co-cast at the same time as the cotton film dope, but separately cast after the cotton film dope is cast. You may.

The casting support may be a drum or a band, but in the case of an optical application such as a polarizing film, since the flatness of the film is important, a high gas concentration on the support after casting is important. The presence of a field is preferable, and the one capable of taking a long time on the support is preferable. Further, in the peeling portion of the membrane from the support, it is preferable to lower the temperature of the support in order to improve the peelability from the support, for example, 20 ° C. or lower.

The cellulose triacetate laminated film of the present invention comprises a support for a photosensitive material, a protective film for a polarizing plate, various plastic films (for example, a movie film, a release film, an insulating film, a calendar film, a sticker film, an OHP ( overhead projector) film, fingerprint collecting film, X-ray film, etc.), developing leader, magnetic recording tape, etc.

[0024]

In the present invention, the cotton film has a good releasability from the casting support, and the cellulose triacetate laminated film can be peeled off from the casting support very easily. Therefore, it is not necessary to add an additive such as a peeling accelerator, and problems such as odor and contamination of the surface of the casting support due to the additive do not occur. In addition, the pulp film ensures resistance to moist heat, and further reduces the cost.

[0025]

EXAMPLES An example of a cellulose triacetate laminated film and a method for producing the same according to the present invention will be described with reference to the drawings.

FIG. 1 is a partial sectional view showing the layer structure of a cellulose triacetate laminated film, FIG. 2 is a schematic view of a production apparatus for producing a cellulose triacetate laminated film,
FIG. 3 is a partially enlarged view of the above manufacturing apparatus.

In FIG. 1, reference numeral 10 indicates a film made of cellulose triacetate prepared from cotton (cotton film).
A film (pulp film) 20 made of cellulose triacetate prepared from pulp is laminated on the upper surface of the film 10.

Next, a method for producing the above cellulose triacetate laminated film will be described.

In FIG. 2, reference numeral 30 is a co-casting die for simultaneously casting two kinds of dopes.
A cotton film tank 31 and a pulp film tank 32 are connected to. A cotton film tank 31 is connected to a lower casting port (not shown) of the co-casting die 30, which is a casting port for directly casting the dope on the casting support, and an upper portion of the co-casting die 30. A pulp film tank 32 is connected to a casting port (not shown) -a casting port for casting the dope which is not in contact with the casting support. Also, a tank for cotton film
31 is filled with a cotton film dope 11 for forming the cotton film 10, and the pulp film tank 32 is filled with a pulp film dope 21 for forming the pulp film 20. Further, pumps 33 and 34 for transporting the dopes are provided between the co-casting die 31 and the tanks 31 and 32, respectively.

Further, reference numerals 35 and 36 are a pair of drums, and a casting band support (hereinafter referred to as a band) 37 as a casting support is wound around the drums 35 and 36. Each drum 35, 36 is provided with a water pipe (or a ventilation pipe) 38 for controlling the temperature of the drum, and a band.
A warm air supply means (not shown) for supplying warm air for drying the dope on the band 37 is provided in the vicinity of 37.

Further, adjacent to the side of one of the drums 35, a peeling roll for peeling off the solidified film.
39 is provided, and the casting port of the co-casting die 31 is adjacent to the upper side of the drum 35.

In order to manufacture the cellulose triacetate laminated film with the above-described manufacturing apparatus, first, the water pipe 38
Then, water adjusted to a predetermined temperature is passed to bring the drums 35 and 36 to a predetermined temperature, and the warm air a is blown onto the band 37 by the warm air supply means. Then, the drum 36 is driven to move the band 37, and the pumps 33 and 34 are also driven to send the respective dopes 11 and 21 to the co-casting die 30. As shown in FIG. 3, the fed dopes 11 and 21 have a two-layer structure in which the cotton film dope 11 is located on the lower side and the pulp film dope 21 is located on the upper side, and are cast onto the band 37. Therefore, only the cotton film dope 11 contacts the band 37, and the pulp film dope 21 does not contact the band 37. After being conveyed in this state and dried with warm air a, it is stripped from the band 37 by the stripping roll 39.

FIG. 4 is a partial cross-sectional view showing the layer structure of another embodiment of the cellulose triacetate laminated film of the present invention, and FIG. 5 is a schematic view of the main part of a production apparatus for producing the above cellulose triacetate laminated film.

The cellulose triacetate laminated film shown in FIG. 4 has a three-layer structure, that is, the cotton films 10, 10 are laminated on both sides of the pulp film 20.

In FIG. 5, the die 40 is a die for three-layer casting, and the pulp film dope 21 is fed to the center and the cotton film dope 11 is fed to both sides thereof so that a three-layer structure is formed. Cast. Other configurations are substantially the same as those of the manufacturing apparatus.

The test results comparing the characteristics of the examples of the present invention and the comparative examples will be described below. [Example 1] Using the following dope, a cotton film layer 10 having a thickness of 5 μm and a thickness of 45 μ shown in FIG.
A cellulose triacetate laminated film consisting of m pulp film layers was prepared. The temperature of the die is 30
℃, the temperature of the hot air was 100 ℃. Dope for cotton film; Cellulose triacetate prepared from cotton 18% by weight (linter cotton with a degree of polymerization of about 350) Triphenyl phosphate 2.5% by weight Mixed solvent 79.5% by weight (methylene chloride / methanol weight ratio = 92/8) Dope for pulp film Cellulose triacetate prepared from pulp 18% by weight (hardwood pulp with a degree of polymerization of about 290) Triphenyl phosphate 2.5% by weight Mixed solvent 79.5% by weight (methylene chloride / methanol weight ratio = 92/8)

Comparative Example 1 Using the same dope for pulp film as in Example 1, a single layer pulp film having a thickness of 50 μm was produced. Other conditions are the same as in Example 1. Film-forming speed test In the production of the films of Example 1 and Comparative Example 1, the time during which film peeling from the support was possible without causing surface defects was measured. Example 1 was 75 seconds, while Comparative Example 1 was 98 seconds, which was about 25% faster than Comparative Example 1.

Example 2 A cotton film having a thickness of 12 μm
m, and the thickness of the pulp film layer was 113 μm, which was the same as in Example 1.

[Embodiment 3] The thickness of the cotton film is 30 μm.
m, and the thickness of the pulp film layer was set to 95 μm.

Comparative Example 2 Using the same pulp film dope as in Example 1, a 125 μm thick single layer pulp film was produced. Other conditions are the same as in Example 1.

Comparative Example 3 Using the same cotton film dope as in Example 1, a 125 μm thick single layer cotton film was produced. Other conditions are the same as in Example 1.

Comparative Example 4 Using the following dope, a monolayer film in which cotton and pulp were mixed was produced. Other conditions are the same as in Example 1. Cellulose triacetate prepared from cotton 2% by weight Cellulose triacetate prepared from pulp 16% by weight Triphenyl phosphate 2.5% by weight Mixed solvent 79.5% by weight (methylene chloride / methanol weight ratio = 92/8) Dope viscosity 513 Poise

[Comparative Example 5] A single layer film in which cotton and pulp were mixed was produced using the following dope. Other conditions are the same as in Example 1. Cellulose triacetate prepared from cotton 5% by weight Cellulose triacetate prepared from pulp 13% by weight Triphenyl phosphate 2.5% by weight Mixed solvent 79.5% by weight (methylene chloride / methanol weight ratio = 92/8) Dope viscosity 545 Poise heat resistance test Example Each of the films of Examples 2 and 3 and Comparative Examples 2 to 5 was attached to glass with an adhesive, stored under conditions of 80 ° C. and humidity of 90% RH, and the time until discoloration was measured by visual observation. The results are shown in Table 1. Plate-out test In continuous production, the time until the surface of the support was contaminated and discoloration was observed was observed and compared. The results are shown in Table 1.

[0044]

[Table 1]

Example 4 A cotton film layer having a thickness of 10 μm shown in FIG. 1 was produced by the production apparatus shown in FIG. 2 using the following dope.
A cellulose triacetate laminated film consisting of 10 and a pulp film layer having a thickness of 90 μm was prepared. The temperature of the die was 30 ° C and the temperature of the hot air was 100 ° C. Dope for cotton film; Cellulose triacetate prepared from cotton 20% by weight (linter cotton with a degree of polymerization of about 350) Triphenyl phosphate 2.8% by weight Mixed solvent 77.2% by weight (methylene chloride / methanol weight ratio = 92/8) Dope viscosity 950 Poise Dope for pulp film; Cellulose triacetate prepared from pulp 16% by weight (hardwood pulp with a degree of polymerization of about 290) Triphenyl phosphate 2.2% by weight Mixed solvent 81.8% by weight (methylene chloride / methanol weight ratio = 92/8) Dope viscosity 350 poise The obtained film was an optically excellent film in which finer irregularities and step-like thickness changes were smaller than those of Example 5 described later.

Example 5 The same as Example 4 except that the viscosity of the cotton film dope and the viscosity of the pulp film dope were both 650 poises. Flatness test The surface of the pulp film layer of each film of Examples 4 and 5 was evaluated by visual observation. As a result, in Example 4, finer irregularities and step-like thickness changes were smaller than in Example 5.

[0047]

INDUSTRIAL APPLICABILITY According to the present invention, the film can be easily peeled from the casting support, and therefore the production rate can be increased. Further, it is possible to sufficiently secure the moist heat resistance.

[Brief description of drawings]

FIG. 1 is a partial sectional view of an example of a cellulose triacetate laminated film of the present invention.

FIG. 2 is a schematic view of a manufacturing apparatus for carrying out the method for manufacturing a cellulose triacetate laminated film of the present invention.

FIG. 3 is a partially enlarged view of a manufacturing apparatus for carrying out the method for manufacturing a cellulose triacetate laminated film of the present invention.

FIG. 4 is a partial cross-sectional view of another embodiment of the cellulose triacetate laminated film of the present invention.

FIG. 5 is a schematic view of another manufacturing apparatus for carrying out the method for manufacturing a cellulose triacetate laminated film of the present invention.

[Explanation of symbols]

10 ... Cellulose triacetate film prepared from cotton 11 ... Dope for cotton film 20 ... Cellulose triacetate film prepared from pulp 21 ... Dope for pulp film 30, 40 ... Co-casting die 31 ... Cotton film tank 32 ... Pulp film Tank 35 ... Drum 37 ... Band

[Procedure amendment]

[Submission date] November 19, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0019

[Correction method] Change

[Correction content]

The dope for the cotton film and the dope for the pulp film may have substantially the same viscosity, but it is preferable that the dope for the cotton film has a high viscosity and the dope for the pulp has a low viscosity. The viscosity is 700P, and the viscosity of the pulp dope is 350P. By setting the viscosity in such a relationship, the flatness of the film surface can be improved without delaying the drying of the film on the casting support.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0036

[Correction method] Change

[Correction content]

The test results comparing the characteristics of the examples of the present invention and the comparative examples will be described below. [Example 1] Using the following dope, a cotton film layer 10 having a thickness of 5 μm and a thickness of 45 μ shown in FIG.
A cellulose triacetate laminated film consisting of m pulp film layers was prepared. Dope for cotton film; Cellulose triacetate prepared from cotton 18% by weight (linter cotton with a degree of polymerization of about 350) Triphenyl phosphate 2.5% by weight Mixed solvent 79.5% by weight (methylene chloride / methanol weight ratio = 92/8) Dope for pulp film Cellulose triacetate prepared from pulp 18% by weight (hardwood pulp with a degree of polymerization of about 290) Triphenyl phosphate 2.5% by weight Mixed solvent 79.5% by weight (methylene chloride / methanol weight ratio = 92/8)

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0044

[Correction method] Change

[Correction content]

[0044]

[Table 1]

[Procedure amendment 4]

[Document name to be amended] Statement

[Name of item to be corrected] 0045

[Correction method] Change

[Correction content]

Example 4 A cotton film layer having a thickness of 10 μm shown in FIG. 1 was produced by the production apparatus shown in FIG. 2 using the following dope.
A cellulose triacetate laminated film consisting of 10 and a pulp film layer 20 having a thickness of 90 μm was produced. Dope for cotton film; Cellulose triacetate prepared from cotton 20% by weight (linter cotton with a degree of polymerization of about 350) Triphenyl phosphate 2.8% by weight Mixed solvent 77.2% by weight (methylene chloride / methanol weight ratio = 92/8) Dope viscosity 950 Poise Dope for pulp film; Cellulose triacetate prepared from pulp 16% by weight (hardwood pulp with a degree of polymerization of about 290) Triphenyl phosphate 2.2% by weight Mixed solvent 81.8% by weight (methylene chloride / methanol weight ratio = 92/8) Dope viscosity 350 poise The obtained film was an optically excellent film in which finer irregularities and step-like thickness changes were smaller than those of Example 5 described later.

Claims (2)

[Claims] 1. A cellulose triacetate laminated film comprising a cellulose triacetate film prepared from cotton and a cellulose triacetate film prepared from pulp. 2. A dope containing cellulose triacetate prepared from cotton and a dope containing cellulose triacetate prepared from pulp are cast so that the dope containing cellulose triacetate prepared from cotton is in direct contact with a casting support. Of cellulose triacetate laminated film characterized by: