SU891688A1 - Method of preparing cellulose low-substituted alkali-soluble xanthogenates - Google Patents

Description

With the help of cellulose, the latter is pretreated with 30-50% aqueous solution of urea, followed by pressing and heat treatment at 140-160 ° C.

Example. The cellulose treatment is carried out with 30-50% aqueous solutions of urea ramium at room temperature, the processing time is 10-30 minutes. The subsequent pressing is carried out up to 170-200% (by weight of cellulose) and the heat treatment of the pressed cellulose is carried out at 140-160 ° C for 1060 minutes. Depending on the concentration of urea in the solution, cellulose carbamates are obtained with varying degrees of substitution {table. one) .

Carbamates of cellulose of various replacement stages are treated with an 18% solution of NaOH at 20 ° C for 160 minutes, followed by pressing to 22.5 times, weight. The pressed alkaline cellulose is crushed and 10-15% carbon disulfide from the mass of pulp is added to it and xanthogenication is carried out for 2 hours at 20 C.

The dissolution of the obtained cellulose xanthates is carried out in a 4% aqueous solution of NaOH for 1 h at 10-20 ° C. The data obtained are given in table. 2

Cellulose xanthates form viscous concentrated solutions containing 8–9% o-cellulose and 56% N aOH,

To clarify the stability of cellulose carbamate obtained at the intermediate stage of the process to alkali, cellulose carbamate preparations with different nitrogen content are treated with 18% -BBM NaOH solution at 20 ° C, then the water is washed to pH 7 and dried. The obtained samples do not contain nitrogen and, therefore, in the process of alkaline treatment, the carbamates are completely washed.

The advantage of the proposed method in comparison with the known method is a more significant reduction in the harmfulness of the production of viscose fiber by reducing the amount of carbon disulfide required for the process. According to a known method, alkaline soluble cellulose xanthates are obtained at a consumption of carbon disulfide of 22–25% by weight (i-cellulose, and according to the proposed method, at a consumption of 10–15%, which is 2-3 times lower than the amount of carbon disulfide that provides a sharp decrease in the harmfulness of viscose production.

When implementing this method, there is no need for equipment that is required in the implementation of the double mercerization method.

The proposed method can be carried out on an industrial scale on existing equipment.

In addition, according to the proposed method, it is possible to spin the obtained alkali cellulose up to two times; when merging a conventional cellulose on an operating apparatus, squeezing to more than 2.75-3 times the weight is not possible. An increase in the degree of squeezing and a decrease in the amount of NaOH in the squeezed and crushed alkaline, respectively. Cellulose significantly reduces the consumption of carbon disulfide for a side reaction with NaOH during xanthogenesis.

Table

10 20 30

170 185 200

0.13

1.08

10 40 60 2.55 0.31 3.8 0.47

Claims (2)

Invention Formula The method of obtaining low-substituted alkaline soluble cellulose xanthates by mercerization and subsequent xanthogenesis of cellulose, in order to simplify the process and reduce the consumption of carbon disulfide, the pulp is pretreated with a 30-50% aqueous solution of urea followed by Table 2 pressing and heat treatment at: 140-160C. Sources of information taken into account in the examination 1. Rogovin Z.A. Fundamentals of chemistry and technology of chemical fibers. M., Himi, 1974, v. 1, p. 213. 2. Rogovin Z.A. and Ginsberg MA Artificial fiber. M., Gizlegprom, 1952, p. 52 (prototype).