SU1763528A1 - Method for preparation of cellulose acetate solution for fibre forming - Google Patents

Abstract

The essence of the invention: cellulose acetate is dissolved in a water-acetone mixture in the presence of trifluoroacetic acid in an amount of 0.006-0.06% by weight of cellulose acetate. 2 tab.

Description

The invention relates to the field of chemical technology, namely, to a method for preparing concentrated solutions of cellulose acetates for forming filaments.

A known method for producing solutions of cellulose acetates includes dissolving cellulose acetate in acetone in the presence of a mixture of modifiers — an organic or inorganic acid and an alkaline earth metal salt 1,

The disadvantage of this method is the need to introduce a large amount of modifying agents, acid and salt (more than 8-10 mg / eq). The process of supplementation consists of two stages: first, an acid is introduced, and then salt. In addition, molding by this method is carried out only from solutions of 20-22% concentration.

A method of preparing a solution for forming filaments, which includes dissolving cellulose acetate in an aqueous-acetone mixture in the presence of a lanthanum acetic acid modifier (2), is closest to the claimed method.

The disadvantage of this method is the high viscosity of the concentrated solutions, which complicates the process of forming filaments.

The aim of the invention is to obtain concentrated solutions with reduced viscosity.

The goal is achieved by the fact that in the method of obtaining a solution of cellulose acetate, including the dissolution of cellulose acetate in an aqueous-acetone mixture in the presence of a modifier, trifluoroacetic acid is used as a modifier in an amount of 0.006-0.06% by weight of cellulose acetate.

Trifluoroacetic acid is introduced directly at the stage of solution preparation or cellulose acetate is pretreated with trifluoroacetic acid vapors in a sealed vessel.

The invention is illustrated by examples.

PRI me R 1 (comparative).

A 25% solution of cellulose acetate in an acetone / water mixture is prepared in the flask.

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about.

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ate

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used in the manufacture of acetate fibers, i.e. 95: 5. The viscosity of the obtained spin solution at 20 ° С was 1180 pz (the data on the molding are presented in Table 1).

PRI me R 2 (comparative).

A 27% cellulose acetate solution is prepared in the flask. The viscosity of such a spinning dope is 2180 pz at 20 ° C. Due to the high viscosity of the solution, it is not suitable for forming filaments.

Froze

To a 27% solution of cellulose acetate in Example 2, was added 2.0 Omg / eq of trifluoroacetic acid. The viscosity of the obtained spin solution is 1370 pz at 20 ° C (data on the molding are presented in Table 1).

PRI me R 4.

1.0 mg / eq of trifluoroacetic acid was added to the solution of Example 2. The viscosity of the spinning solution is 1350 pz at 20 ° C. From the obtained cellulose acetate acetate solution, threads are formed (see data in Table 1).

PRI me R 5.

0.2 mg / eq of trifluoroacetic acid was added to the solution of Example 2, the viscosity of the solution was 1340 pz. This dope of cellulose acetate is tested for stability over time, 7 viscosity measurements have been made over the course of a month — the viscosity remains almost unchanged and is 1340–1345 pz (data on molding are presented in Table 1).

PRI me R b (comparative).

To the spin solution of Example 2, 0.11 mg / eq of trifluoroacetic acid was added. The viscosity of the resulting cellulose acetate solution was 1590 pz. (Data on the molding are presented in table 1).

PRI me R 7.

In a hermetically sealed vessel filled with trifluoroacetic acid, a mesh with an industrial sample of cellulose acetate is placed and treated with vapors of trifluoroacetic acid until it absorbs 0.4 mg / eq. trifluoroacetic acid. Further, a 27% spinning solution is prepared from such cellulose acetate, the viscosity of which is 1330 pz at 20 ° C. The obtained spinning solution of cellulose acetate is formed into threads. Data on their physico-mechanical characteristics are given in table 1.

Comparative data on the viscosity of the solutions and the molding conditions of the known and proposed methods are presented in Table 2.

Claims (1)

Invention Formula A method for preparing cellulose acetate solution for forming yarns, including dissolving cellulose acetate in an aqueous-acetone mixture in the presence of a modifier, characterized in that, in order to obtain a concentrated solution with reduced viscosity, trifluoroacetic acid is used as a modifier in an amount of 0.006-0. , 06% of mabs cellulose acetate. T b b p and c and I