SU1305227A1 - Method of bleaching pulp - Google Patents

Abstract

The invention relates to the α-pulp and paper industry and reduces the degree of destruction of cellulose while maintaining its whiteness. Unbleached sulphate pulp from coniferous woods, after chlorination and alkali, are treated with sodium hypochlorite solution. Before being treated with sodium hypochlorite, eosin or erythrosine in an amount of 0.05-0.50% by weight of absolutely dry fiber is added to the pulp. 2 tab.

Description

1 13

This invention relates to pulp bleaching processes and is intended for use in the pulp and paper industry.

The purpose of the invention is to reduce the degree of destruction of cellulose.

According to the proposed method, cellulose bleaching with sodium hypochlorite is carried out in the presence of eosin (2,4, 5,7-tetrabromf uorescein) or erythrosine (2,4,5,7 - tetraiodofluorescein), added in an amount of 0.05-0.50 % by weight of absolutely dry fiber.

Example 1. Unbleached sulphate pulp from coniferous wood species after the chlorination and alkali stage, with a delignification degree of 9.0 permanganate units (p.u.) and a polymerization degree of 1500

sodium hypochlorite solution (at a rate of 2% for active chlorine to absolutely dry fiber) for 60 minutes at 60 ° C. Before hypochlorite treatment, add to the pulp mass, eosin or erythrosine in an amount of 0.05-0.50 % by weight is absolutely cyxcJro fiber. At the same time, under the same conditions, control bleaches are carried out without an additive and with the addition of 3,6-di-tert-butyl pyrocatechol (3,6-DTBPK) as an inhibitor of cellulose destruction.

The results of the analysis of cellulose after hypochlorite bleaching are presented in table. one.

From the data table. 1 that cellulose bleaching with sodium hypochlorite in the presence of eosin and erythrosine in an amount of 0.05-0.10% by weight of absolutely dry fiber increases the degree of polymerization (viscosity), which indicates a decrease in the degree of destruction of cellulose while maintaining its whiteness.

PRI mme R 2. Sulfate pulp from coniferous woods after the chlorination and alkali stage, with a delignification degree of 9.0 bp. and polymerization degree 1500 is treated with sodium hypochlorite solution (at a rate of 2% for active chlorine to absolutely dry fiber) with different consumption of NaOH for 60 minutes at. Bleaching is carried out both in the presence of eosin additives and without additives. The parameters of the pulp after hypochlorite bleaching are presented in table. 2

The results of the experiments show that the addition of eosin can reduce the decrease in the degree of polymerization and, therefore, decrease the degree of destruction while reducing the consumption of NaOH and maintaining the whiteness of the pulp.

Table 1

 five

20

Control from 45

table 2

Continuation of table 2

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0.5 0.4 0.3

0.2

71.8 72.0 72.0 72, A

1090 1080 1040 1030

Claims (1)

Invention Formula A method of bleaching pulp, including chlorination, alkali and the treatment with sodium hypochlorite in the presence of an organic additive, o t is characterized in that, in order to reduce the degree of destruction of cellulose, as an organic Supplements use zosin or spectrosin in an amount of 0.05-0.50% by weight of absolutely dry fiber.