RU1807146C - Process for manufacturing offset paper - Google Patents

Abstract

SUMMARY OF THE INVENTION: According to a method for manufacturing paper for offset printing, polyacrylamide is added to the paper pulp in an amount of 0.02-0.30% by weight of absolutely dry fiber before being diluted with polyacrylamide acidic water. The ratio of polyacrylamide added to the pulp and polyacrylamide used to treat recycled water / is from 1: 1 to 10: 1. 1 tab.

Description

The invention relates to the pulp and paper industry and can be used in the production of paper with a high content of high yield semi-finished products.

The aim of the invention is to improve the quality of paper and the intensification of the process by increasing the degree of removal of solutes from the diluted pulp.

The goal is achieved by the fact that, according to the method of making paper, comprising treating the acidic circulating water with PAA, diluting the pulp with treated circulating water, according to the invention, prior to diluting the treated circulating water with PAA, PAA is added in an amount of 0.02-0. 3% by weight of absolutely dry fiber (a.s.w.) with a mass ratio of the specified PAA and PAA fed to the treatment of recycled water, from 1: 1 to 10: 1.

In the proposed method, there is an improvement in the quality of paper containing

wood pulp, and the intensification of the process with a simultaneous increase in the retention of kaolin and fine fiber.

The proposed fractional introduction of PAA into paper pulp and circulating water when a large quantity of high-yield semi-finished products is contained in the pulp leads to the fact that dissolved substances contained in circulating water are sorbed on kaolin and fine fibers, and those contained in the pulp are sorbed on large fibers and withdrawn from the paper flow. As a result, the efficiency of flocculating additives introduced into the paper pulp just prior to casting is improved, in order to ensure the retention of fines on the PM paper, to intensify the process, and to improve the quality of the paper. In this case, the distribution of the flow rate of PAA flows into paper pulp and recycled water depends on the concentration of fibrous mass and, as a result, on the contamination of the flow with organic substances.

WITH

about

h

Ј o

sstv. The concentration of fiber in the pulp before mixing it with recycled water is several times higher than the concentration of fiber in recycled water, which requires a large consumption of PAA.

PRI me R 1. Prepare pulp from 24% sulfate softwood pulp, milled to 28 ° SH, 38% thermomechanical mass with a degree of grinding 75 ° SH, 38% of the chemical-thermomechanical mass with a degree of grinding 78 ° SH, concentration the pulp is 3%, 8% of the mass of A. is introduced into the pulp rosin glue and 15% by weight kaolin. Next, anionic PAA is introduced into the paper pulp in an amount of 0.1% by weight of a.s. at. and aluminum sulfate was added to a pH of 4.9 wt. The mass is kept for 40 minutes. Anionic PAA in the amount of 0.02% of the mass of a.c.w. is introduced into the acidic circulating water (pH 4.8) taken from the BDM circulating water collector, after which the treated circulating water is mixed with the prepared paper pulp. The concentration of finished paper pulp is 0.6%. Next, paper pulp is cast in the usual manner using flocculants (PAA, PEI, etc.) just before the casting in the amount of 0.02% of the mass of the a.v.v., pressed and dried. Paper tests are carried out according to standard procedures.

The remaining experiments were performed similarly to experiment 1. The ratio of PAA introduced into the paper pulp and recycled water, as well as paper quality indicators and process parameters are given in the table.

In parallel, for comparison, control experiments (4,6,6,7) were carried out, in which the foreign dosages of anionic PAA were given to the mass and to the circulating water. Experience 8 was performed according to the technology described in the prototype (example 6), but using the fibrous composition described previously.

As can be seen from the table, the proposed method of paper production by fractional

treatment of PAA recycled water and paper pulp with their subsequent mixing leads to an increase in mechanical strength indicators: breaking length by 16-25% (rel.), compared with the processing of PAA only pulp (example 6) or only recycled water (example 7), resistance to fracture by 40-100%, structural strength according to Scott by 24/36% (rel.), surface strength to plucking by 26-33%, dehydration rate by 18-36%, increase filler retention.

The optimum ratio of PAA introduced into the pulp and PAA introduced into the circulating water is from 1: 1 to 10: 1. The optimal consumption of PAA introduced into the paper pulp is 0.02-0.3% by weight of ac. When the consumption of PAA in paper pulp more than 0.3% (experiment 5) is not observed

further improvement of the properties, which leads to overuse of PAA. With the consumption of PAA supplied to the pulp in an amount of less than 0.02% (experiment 4), there is no improvement in the quality of the paper compared to the prototype and an improvement in the dewatering rate of the pulp.

Claims (1)

SUMMARY OF THE INVENTION A method for producing paper for offset printing, comprising treating acidic circulating water with polyacrylamide, diluting pulp with treated circulating water, and casting a web, wherein, for the purpose of improving the quality of paper and intensifying the process by increasing the degree of removal of dissolved substances from the diluted paper pulp in the manufacture of paper containing wood pulp, before dilution with treated recycled water, polyacrylamide is introduced into the paper pulp in an amount of 0.02-0.30% by weight absolutely dry fiber at a mass ratio of the specified polyacrylamide to polyamide fed to the treatment of recycled water, from 1: 1 to 10: 1.  Reverse water is treated with aluminate and, together with PAA with a pH of 7 in the presence of cationic PAA, the anionic PAA consumption is 0.03%. cationic. PAA 0.03%.