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Cellulose diacetate for retardation film

A technology of cellulose diacetate and phase difference film, which is applied in the direction of instruments, optics, optical components, etc., can solve the problems of inability to achieve uniform chemical composition and uneven molecular weight distribution, achieve uneven molecular weight distribution, reduce bright spot foreign matter, chemical Composition of uniform effect

Active Publication Date: 2012-07-18
DAICEL CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Therefore, in the synthesis of cellulose acetate, the desired opposite characteristics of uniform chemical composition and non-uniform molecular weight distribution cannot be achieved.

Method used

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  • Cellulose diacetate for retardation film
  • Cellulose diacetate for retardation film

Examples

Experimental program
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Effect test

Embodiment 1

[0148] The hardwood prehydrolyzed kraft pulp with an α-cellulose content of 98.4% by weight was pulverized into a cotton form with a disc refiner. 26.8 parts by weight of acetic acid were sprayed into 100 parts by weight of pulverized pulp (moisture content 8%), stirred and mixed sufficiently, and then pretreated by standing for 60 hours and activated (activation step). The activated pulp was added to a mixture containing 323 parts by weight of acetic acid, 245 parts by weight of acetic anhydride, and 13.1 parts by weight of sulfuric acid, and the acetylation was carried out for 90 minutes by adjusting the maximum temperature from 5°C to 40°C over 40 minutes. A neutralizing agent (24% magnesium acetate aqueous solution) was added over 3 minutes, and the amount of sulfuric acid (the amount of aged sulfuric acid) was adjusted to 2.5 parts by weight. Furthermore, after raising the temperature of the reaction bath to 75° C., water was added to set the reaction bath moisture (cured...

Embodiment 2~6、8、9、12~13

[0149] (Examples 2~6, 8, 9, 12~13 and comparative examples 1~7, 9, 11~12)

[0150] The preparation conditions of cellulose acetate are shown in Table 1. Under the conditions shown in Table 1, the same operation as in Example 1 was carried out to obtain cellulose diacetate.

[0151] [Table 1]

[0152]

Embodiment 7

[0154] Purification of cellulose diacetate

[0155] Disperse 100 parts by weight of the mixture containing cellulose diacetate obtained in Example 2 in 1,000 parts by weight of dichloromethane at room temperature (about 22° C.) Centrifugation was performed to obtain a gel-like precipitate. The gel-like precipitate was dispersed in 2,000 parts by weight of methanol, and centrifuged under the above conditions to obtain a precipitate. This methanol was washed twice. Furthermore, washing|cleaning was carried out twice using 50 weight% acetone aqueous solution instead of methanol. Thereafter, it was washed twice with 1,000 parts by weight of water, dried under reduced pressure at 40° C. until it became a constant weight, and 61 parts by weight of purified cellulose diacetate was obtained.

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Abstract

Disclosed is a cellulose acetate that enables a cellulose acetate optical film, which expresses optical properties when stretched, to achieve excellent stretchability and excellent optical properties after being stretched. Specifically disclosed is a cellulose diacetate for a retardation film, which has a total degree of substitution of acetyl groups of 2.27-2.56. The cellulose diacetate for a retardation film is characterized by having a degree of dispersion (Mw / Mn) of more than 3.0 but 7.5 or less, a degree of substitution at the 6-position of 0.65-0.85, a half width of the distribution of the degree of acetylation of 1.0-2.3 and a viscosity average degree of polymerization of 182-213 (inclusive). It is preferable for the cellulose diacetate for a retardation film to have a 6% viscosity of 120-230 mPas and a weight average molecular weight (Mw) of 205,000-235,000 (inclusive).

Description

technical field [0001] The present invention relates to a cellulose diacetate used for a cellulose ester film, an optical film, especially a retardation film, which has excellent optical characteristics, is easy to control the retardation value, especially Rth, and has uniform retardation characteristics. Background technique [0002] In recent years, thin and lightweight notebook computers have been developed. Along with this, there are increasing demands for thinner protective films and higher performance of polarizers used in display devices such as liquid crystal display devices. A liquid crystal display device expresses a display by controlling the polarization of liquid crystals. Therefore, a polarizer is required for the display, and a film obtained by stretching an iodine-containing PVA film is generally used as a polarizer. Since the polarizer is fragile, a polarizer protective film is used to protect the polarizer. As the polarizing plate protective film, a cellu...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G02B5/30C08B3/06G02F1/13363
CPCC08J5/18G02B5/3083C08J2301/12C08B15/02C08L1/12C08B3/06G02F1/13363C08L2666/26G02B5/30
Inventor 岛本周阿隅雄也
Owner DAICEL CORP
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