Solvent casting process, polarizing plate protective film, optically functional film and polarizing plate

Inactive Publication Date: 2003-03-27
FUJIFILM HLDG CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

0007] Solving the foregoing problems, an object of the present invention is to provide a process for so

Problems solved by technology

Therefore, particularly great drying rate is required between the casting and the point of being stripped off.
However, it was found that, according to drying conditions, problems occur, such as foaming and degradation of film properties, such as, mechanical strength, transparency, retardation, flatness, etc.
On the other hand, in the case that the cast film containing volatile components in a high concentration is stripped off from a casting support by a tenter machine of a clip type, the film breaks at the portion caught by the clip, and it is difficult to continue carring the film by the tenter.
Therefore, the high-speed casting and improvement in the manufacturing speed of the film are difficult.
In addition, since the film stripped off from the casting support contains volatile

Method used

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  • Solvent casting process, polarizing plate protective film, optically functional film and polarizing plate
  • Solvent casting process, polarizing plate protective film, optically functional film and polarizing plate
  • Solvent casting process, polarizing plate protective film, optically functional film and polarizing plate

Examples

Experimental program
Comparison scheme
Effect test

example 3

Preparation of Optically Functional Film

[0160] Onto one surface of the triacetylcellulose film [thickness: 100 .mu.m, {(nx+ny) / 2-nz}.times.d=70 nm] prepared in Example 1, a gelatin layer (layer thickness: 0.1 .mu.m) was applied. Subsequently, a coating solution of long-chain alkyl-modified polyvinyl alcohol ("MP-203", Kuraray Co., Ltd.) was applied onto the gelatin layer and dried for 30 seconds by warm wind at 110.degree. C., followed by rubbing the coated film to form an oriented film. On the surface of the oriented film, a discotheque liquid crystal was applied. In details, a coating solution containing 20 mass % of the compound TE-8 (m=4) described in JP 8-43625A, and 0.1 mass % of photoinitiator (Ilgacure 907, produced by Ciba Geigy Japan Co., Ltd.) in methyl ethyl ketone was applied by a slide coater at a coating velocity of 20 m / minute, with a coating amount of 12 cc / m.sup.2, to form the discotheque liquid crystal layer with a thickness of 2.4 .mu.m. The discotheque liquid cr...

example 5

[0169] Dope E' was the same as Dope E except that matte agent was removed from Dope E in Example 4, and Dope F was the same as Dope E in Example 4. Using a multi-manifold type die, the dopes were simultaneously cast on the casting support in the same way as Example 4, while Dope E' formed the core part corresponding to the thickness of 70 .mu.m after drying, and Dope F formed outer layers on both surfaces of the core part corresponding to the thickness of 5 .mu.m after (trying. Then, the film stripped off from the casting support was carried by the pin tenter machine with the conditions of residual solvent of 280 mass % and a temperature -2.degree. C. The other conditions for casting and drying the film were the same as Example 4.

example 7

[0176] The dopes were cast and dried under the same conditions as Example 6 with the exception that the mean thickness of the film was 135 .mu.m, the residual solvent quantity of the film on stripped off from the belt being the casting support was 150%, the temperature and the thickness of the film in the area of being carried by the pin tenter was respectively 12.degree. C. and 200 .mu.m and the residual solvent quantity was 220%.

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Abstract

A process for solvent casting which comprises, casting a dope from a casting die onto a casting support, drying the cast dope on the casting support to form film, stripping off the film from the casting support, and further drying the film, wherein the dope has a solid matter content of from 17 mass % to 30 mass %, and a mean drying rate between the casting of the dope and the stripping off is more than 300 mass %/minute and not more than 1000 mass %/minute is proposed. The process for solvent casting for producing a film comprising the steps of casting a dope from a casting die to a casting support, forming the film by drying the dope to some extent, stripping off the film from the casting support and further drying the film while conveying the film with carrying it at both side edges of the film by a tenter under a specified condition is also proposed. The high-speed solution film forming methods enable to produce the film having good quality with stable conveying and with stable drying especially in the conveying of the film by the tenter machine in the drying steps after stripping off from the casting support.

Description

[0001] The present invention relates to a solvent casting process for producing cellulose triacetate film, etc. and polarizing plate protective film, optically functional film, or polarizing plate using the film produced by the solvent casting process.[0002] Generally, a part of films, such as cellulose acetate, polycarbonate, and cellophane are produced by solvent casting. In the solvent casting process, dope being a polymer solution is cast from a casting die onto a casting support of belt type or drum type, stripped off after being dehumidified to some extent on the casting support, dried while being carried by a tenter machine with being held at both side edges, and further dried while being conveyed over rollers (JP 62-46625A, JP 62-46626A, etc.).[0003] In order to improve productivity in such a solvent casting process, it is necessary to rapidly strip off the dope cast on the casting support. As a result, various technics for stripping off the dope quickly have been developed,...

Claims

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Application Information

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IPC IPC(8): B29C41/26B29D7/01C08J5/18
CPCB29C41/26B29D7/01B29K2001/00B29K2001/12B29K2023/38B29K2069/00B29K2077/10C08J5/18
Inventor TSUJIMOTO, TADAHIRO
Owner FUJIFILM HLDG CORP
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