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Preparation process of cellulose acetate
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A technology of cellulose triacetate and preparation process, applied in the field of polymer chemistry, can solve the problems of uneven activation, low degree of esterification, low viscosity, etc.
Inactive Publication Date: 2013-01-02
LUZHOU NORTH CHEM IND
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Abstract
Description
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Problems solved by technology
However, there are problems such as uneven activation in this method, resulting in uneven degree of esterification of the product, low degree of esterification, and low viscosity.
Method used
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Embodiment 1
[0033] 1. 1 part by weight of cellulose is activated with glacial acetic acid at 30°C for 1.2h, the mass ratio of cellulose to glacial acetic acid is 1:15, and cellulose refers to refined cotton.
[0034] 2. In the esterification process, the acetic acid in the activation process is directly used as the solvent, and the catalyst is added first. The amount is 0.006 times the weight of the cellulose. The catalyst refers to sulfuric acid with a mass concentration of 98%. Then add acetic anhydride as a reaction solution to fully acetylate the cellulose, and the amount is 6 times the weight of the cellulose. The esterification temperature is 45°C and the time is 3.5h. The use of lower temperature and less catalyst for the esterification reaction is beneficial to obtain higher viscosity cellulose acetate during the esterification process.
[0035] 3. Hydrolyze, add 85% acetic acid aqueous solution, add 0.5 times the amount of cellulose, and add slowly while stirring when the temperature...
Embodiment 2
[0042] 1. 1 part by weight of cellulose is activated with glacial acetic acid at 40°C for 1 hour, and the mass ratio of cellulose to glacial acetic acid is 1:20. Cellulose refers to materials with rich cellulose content such as refined cotton.
[0043] 2. In the esterification process, the acetic acid in the activation process is directly used as the solvent, and the catalyst is added first, and the amount is 0.05 times the weight of the cellulose. The catalyst refers to sulfuric acid with a mass concentration of 98%. Then add acetic anhydride as the reaction solution to fully acetylate the cellulose, and the amount is 4.5 times the weight of the cellulose. The esterification temperature is 50℃ and the time is 3h. The use of lower temperature and less catalyst for the esterification reaction is beneficial to obtain higher viscosity cellulose acetate during the esterification process.
[0044] 3. Hydrolysis. The hydrolyzed solution is an 86% acetic acid aqueous solution, and the ad...
Embodiment 3
[0050] 1. 1 part by weight of cellulose is activated with glacial acetic acid at 20°C for 1 hour, and the mass ratio of cellulose to glacial acetic acid is 1:8. Cellulose refers to a substance rich in cellulose such as refined cotton.
[0051] 2. In the esterification process, the acetic acid in the activation process is directly used as the solvent, and the catalyst is added first, and the amount is 0.01 times the weight of the cellulose. The catalyst refers to sulfuric acid with a mass concentration of 98%. Then add acetic anhydride as the reaction liquid to fully acetylate the cellulose, and the dosage is 6 times that of cellulose. The esterification temperature is 20℃, and the time is 8h. The use of lower temperature and less catalyst for the esterification reaction is beneficial to obtain higher viscosity cellulose acetate during the esterification process.
[0052] 3. Hydrolysis. The hydrolyzed solution is an 89% acetic acid aqueous solution, and the amount added is 1.1 time...
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Abstract
The invention belongs to the field of polymer chemistry, and relates to a preparation process of cellulose acetate. The process is easy to operate, and the product has high substitution degree and high viscosity. The preparation process comprises the following steps of: A, activating 1 weight part of cellulose by using 8 to 20 weight parts of glacial acetic acid at the temperature of between 20 and 60 DEG C; B, adding 4 to 6 weight parts of acetic anhydride and 0.005 to 0.05 weight part of catalyst, and performing esterification at the temperature of between 20 and 58 DEG C for 3 to 8 hours; C, adding 0.5 to 1.5 weight parts of high-concentration aqueous solution of acetic acid at the temperature of between 10 and 25 DEG C, and reacting till the content of the acetic acid is 60.5 to 62.5 percent, wherein the high-concentration aqueous solution of acetic acid is 80 percent aqueous solution of acetic acid; D, adding 0.3 to 1 weight part of 5 to 15 percent aqueous solution of acetate, and reacting for 15 to 45 minutes at normal temperature; and E, filtering, settling and granulating. By the process, a large amount of heat released in acetic anhydride reaction is avoided, and the substitution degree of cellulose is reduced. By adopting a low-temperature hydrolysis mode, the acetic acid content of fibers is more than or equal to 60.0 percent in high substitution degree; and the cellulose acetate is particularly suitable for manufacturing polarizing films in optical elements.
Description
Technical field [0001] The invention belongs to the technical field of polymer chemistry, and particularly relates to a preparation process of cellulose acetate. Background technique [0002] Cellulose Acetate (Cellulose Acetate, referred to as CA) is a cellulose ester obtained by acetylation of natural cellulose, and is an extremely important cellulose organic acid ester. According to its degree of esterification, it can be divided into multiple levels. The degree of esterification is between 2 and 3 and the amount of combined acetic acid is 48.5-58.8% is called cellulose diacetate; the cellulose is completely esterified, and the degree of esterification is 3, and the amount of combined acetic acid is 60.0-62.5 %, known as Tri-cellulose Acetate (TCA). [0003] As a photographic material, cellulose triacetate film has been widely used. And because the cellulose triacetate film has excellent smoothness and optical anisotropy, it is also used in the manufacture of liquid crystal d...
Claims
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Application Information
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