SU651010A1 - Method of obtaining copolymers of cellulose acetate - Google Patents

Description

(54) A METHOD FOR OBTAINING COPOLYMER ACETATE PULP OF LIQUID, eg, acetone or methylene chloride, i.e. According to the existing technology of the dry molding method. The purpose of the invention is to obtain from polymers soluble in low boiling organic solvents and to simplify the process. For this, grafting is carried out on freshly planted cellulose diacetate with an acetic acid content in the aqueous suspension of 1.5-3.0%, and using vinyl acetate and methacrylic acid as a mixture of vinyl acetate monomers, taken in a ratio of 19: 11: 1, respectively. Cellulose acetate used in graft copolymerization is prepared according to a known technology. The preactivated cellulose is treated with an acetylating agent, followed by neutralization of the acetylation catalyst. The resulting cellulose triacetate is scrubbed, then the cellulose diacetate is precipitated with washing to an acidity of 1.5-3.0%. The bitumen suspension of cellulose acetate is evacuated, heated to 60 ° C and this mixture of vinyl monomers is added. The copolymerization is carried out in an inert gas in the presence of an initiator at a temperature of 80 ° C. Thus, the process of modifying cellulose acetate is combined with the process of its preparation and eliminates the stages of final washing, drying, packaging the finished (unmodified) cellulose acetate, and also obtaining a suspension from it, which is necessary for carrying out the copolymerization by a known method. The resulting cellulose acetate copolymer is soluble in low-boiling organic solvents and can be used to form fibers or films or other products from solutions using a dry method. Copolymer working solutions are less structured and have a lower viscosity than solutions of unmodified cellulose acetate. The presence of carboxyl groups and vinyl acetate in the resulting copolymer makes it possible to obtain products with lower electrification, increased abrasion resistance, better coloration, high hygroscopicity, and, in case of use for varnishes, with increased adhesion to metal and wood compared to unmodified cellulose acetate. The characteristics of the cellulose acetate copolymer fiber according to the invention in comparison with the unmodified acetate fiber are given in the table.

10.3

Acetate

Example 1. Take 5.3 g of loosened cellulose, loaded into the activator and at a temperature activate 2.0 kg of acetic acid. The activated cellulose from the activator is transferred to the apetil tor, where 7.1 l of acetic anhydride is treated at 18–22 ° C for 30 min. Cellulose acetylation is then carried out in three stages: first, 1.5 hours with a mixture of 10 liters of methylene chloride, 2 liters of acetic acid and 6 ml of sulfuric acid, then 1 hour at 18-22 ° C with a mixture of 5 liters of methylene chloride, 2 liters of acetic acid acid and 6 ml of sulfuric acid and, finally, for 6-9 hours at 18-4 O With a mixture of 5 l of methylene chloride, 2 l of acetic acid, lY, l ml of sulfuric acid and 11 ml of perchloric acid.

12

3,

5550

3.6 10

20962

At the end of the acetylation process, the resulting triacetate is hydrolyzed to diacetate by treatment with a mixture of 2.8 l of water and 5.4 acetic acid while simultaneously stripping methylene chloride. Thereafter, the cellulose diacetate is precipitated from the syrup.

The diacetate precipitate is decanted free from the mother liquor and washed with desalted water. The mother liquor and the washing waters are fed to the regeneration of acetic acid, and desalted water is supplied to the plant with cellulose diacetate to obtain the module of bath 8. The content of acetic acid in the aqueous suspension is 1.5-3.0%.

Claims (3)

The resulting suspension when salinization is deaerated by pumping and heating to. Upon reaching the temperature of 60 ° C, the vacuum is eliminated with nitrogen and, in a stream of nitrogen, the previously prepared cm monomers consisting of 3.32 kg of acetate wines, 0.18 kg of methacrylic acid (ratio 19: 1) and 0.056 kg ne are fed into the suspension. recy benzoyl. The reaction mass is heated to 80 ° C for 20-30 minutes and copolymerization is carried out for 3 hours. After 3 hours, a sample of the mother liquor is taken and the content of monomers is determined. It is 0.1%. The contents of the apparatus are cooled until the mixer is stopped and the suspension is set aside. The decantation mother liquor is drained, and the copolymer product precipitate is poured with desalted water. Then crushed, washed, dried and packed. The yield of cellulose diacetate copolymer is 9 kg. The resulting copolymer contains 1.0% carboxyl groups, the viscosity of its 25% aqueous solution in acetone is 100 seconds, and the moisture content is 1.5%. Example 2. A copolymer of diacetate and cellulose was prepared analogously to example 1, using a mixture consisting of 2.8 kg of vinyl acetate, 0.7 kg of methacrylic acid (4: 1 ratio) and 0.056 kg of benzoyl peroxide as vinyl monomers. The obtained copolymer contains 3.6% of carboxyl groups, the viscosity of its 25% aqueous solution in acetone corresponds to a time of 500 s, the moisture content is 1.5%. Example 3. Cellulose diacetate copolymer is obtained as in Example 1. A mixture of 2.45 kg of vinyl acetate, 1.05 kg of methacrylic acid (ratio 7: 3) and 0.056 kg of benzoyl peroxide is used as the vinyl monomers. . The resulting copolymer contains 4.7% of carboxyl groups, the viscosity of its 25% aqueous solution in acetone corresponds to a time of 480 s, the moisture content is 1.5%. Example 4. A cellulose diacetate copolymer was prepared as in Example 1. A mixture of 1.75 kg of vinyl acetate, 1.75 kg of methacrylic acid (1: 1 ratio) and benzoyl peroxide was used as vinyl monomers. The resulting copolymer contains 7.1% carboxyl groups, its 25% solution in acetone has a viscosity corresponding to a time of 520 s, a moisture content of 1.5%. The method allows to obtain copolymers of cellulose diacetate from which articles can be molded (fibers, films, etc.). At the same time, the obtained molded products have good physicomechanical and sanitary-hygienic properties. The copolymerization of cellulose acetate and vinyl monomers is simplified because it eliminates the steps of washing, drying and packaging unmodified cellulose acetate, as well as preparing a suspension from it. The method, as well as the processing of the product of this method, can be performed on existing industrial equipment. Claims A method for producing cellulose acetate copolymers by grafting vinyl monomers onto cellulose diacetate in an aqueous suspension, characterized in that, in order to obtain copolymers soluble in low-boiling organic solvents, and to simplify the process, grafting is carried out on the freshly precipitated cellulose diacetate on the content of the content. in aqueous suspension 1.5-3.0%, and as a vinyl monomer a mixture of vinyl acetate and methacrylic acid is used, taken in a ratio of 19: 1 - 1: 1, respectively. Sources of information taken into account in the examination 1. French patent number 1399515, cl. From 08 V. 1965. 2. Authors certificate of the USSR 364693, cl. D 01 F 2/28, 1973. 3. US patent 2,865,872, cl. 260-17, 1958.