Multistep sulfite cellulose bleaching process

FIELD: paper-and-pulp industry.

SUBSTANCE: invention is designed for use in production of bleached sulfite cellulose with reduced level of resins and fats for manufacturing paper and cardboard in multistep bleaching processes. Process according to invention comprises treatment of pulp with sodium hypochlorite solution in presence of chemical additive, bucking and souring of pulp, sad chemical additive being aqueous mixture of ethoxylated fatty alcohols having density 0.99-1.1 g/cm3 in amount 0.04-0.08% of the weight of absolutely dry cellulose. Bucking of pulp is carried out in presence of detergent named VIK-1 used in amount 0.1-0.3% of the weight of absolutely dry cellulose. Souring is carried out in presence of aqueous solution of quaternary polyammonium compound (BZK-2) used in amount 0.4-0.8% of the weight of absolutely dry cellulose.

EFFECT: reduced gumminess of bleached sulfite cellulose and enhanced whiteness at the same cost.

1 tbl, 3 ex

 

The invention relates to the pulp and paper industry and can be used in the production of bleached pulp with a lower content of resins and fats for the manufacture of paper and cardboard in the processes of multi-stage bleaching.

The known method a multi-stage bleaching of sulfite pulp, comprising the step be in the presence of polyoxyethylene parameningeal branched nonalnum radical and a degree of oksietilirovannye 10-12 (see SU 1527350, A1, D 21 C 9/12, 07/12/89).

When this chemical additive is introduced in a quantity of 0.2-0.5% of the mass of absolutely dry pulp.

The bleached pulp obtained in a known manner, characterized by a reduced content of resins and fats (0,39-0,51%) and high mechanical strength (breaking length - 7800 m, fracture resistance - 1200 CDP).

A known method of reducing tar sulfite pulp by finishing it with the use of surfactants in an alkaline environment (see Aichanov V.R. and other Lower tar sulfite viscose cellulose with the help of surfactants. Abstract information "Pulp, paper, and paperboard" - M.: 1970, No. 18, p.7-8).

At the same time as surfactants in a known way using detergent Schkopau, W-OF representing a product of oksietilirovannye mixture of technical fatty alcohols.

Cellulose, refined from the local way characterized by the following tar the use of additives in the amount of 0.5% by weight of the fibers: the content of the resin in the cellulose - 0,23%; the use of additives to 1.0% by weight of the fiber content of resin in the cellulose - 0,17%; the use of additives to 1.5% by weight of the fiber content of resin in the cellulose of 0.07%.

However, the known method does not allow to obtain a bleached sulfite pulp with the required quality level.

The closest analogue of the claimed invention to the technical essence is a way of multi-stage bleaching pulp, comprising the treatment of pulp with a solution of sodium hypochlorite in the presence of chemical additives, bucking pulp and kislovka (see SU 1618802 A1, D 21 9/08, 11.04.1984). At the same time as additives in a known way using hypophosphite sodium or waste production in the amount of from 0.005 to 0.060% by weight of absolutely dry pulp.

The known method provides improved mechanical strength of the pulp and white, and low mass fraction of the resin in the cellulose.

When the bleaching of pulp scheme G-G-K mass fraction of the resin bleached sulfite pulp 0.33 to 1.05%, the bleaching of pulp by the scheme X-S-X-G-D-G-K mass fraction of the resin bleached sulfite pulp is 0.20-0,52%, the bleaching of pulp scheme G-X-(D-Y)-G-G-D-G-D-mass is I share the resin bleached sulfite pulp is 0.17-0.40 per cent, where G is the treatment with sodium hypochlorite; - kislovka; X is chlorine; Y is bucking; Dr. chlorine dioxide.

However, the known method does not allow to obtain a bleached sulfite pulp with the required level of quality of the wood increased tar, such as pine, a mixture of aspen and birch.

New technical result from use of the proposed technical solution is the reduction of tar bleached sulfite pulp while increasing whiteness while maintaining its low cost.

This new technical result is achieved in that in the method a multi-stage bleaching of sulfite pulp, including the treatment of pulp with a solution of sodium hypochlorite in the presence of chemical additives, bucking pulp and kislovka as chemical additives on the processing stage of the pulp with sodium hypochlorite solution using an aqueous mixture of ethoxylated fatty alcohols with a density of 0.99-1.1 g/cm3in the amount of 0.04 to 0.08% by weight of absolutely dry pulp, bucking pulp is carried out in the presence of detergent VIC-1 in the amount of 0.1-0.3% of the mass of absolutely dry pulp, and kislovka are in the presence of an aqueous solution of Quaternary polyammonium compounds AFC-2 in the amount of 0.04 to 0.08% by weight of absolutely dry pulp.

<> When this chemical additives used in the stages hypochlorite treatment, be and kislovka receive industrially by the following normative documents:

- water mixture of ethoxylated fatty alcohols with a density of 0.99-1.1 g/cm3(UMC-1) TU 2484-114-05800142-2002;

detergent VIC-1 in THE 2381-002-24063040-2002;

aqueous solution of Quaternary polyammonium compounds AFC-2 on THE other 2484-073-05800142-2001.

The aggregate used in the proposed method, chemical additives in the stated quantitative range allows to obtain a bleached sulfite pulp, high whiteness, low-tar and fats.

It should be noted that the use of these chemical additives changes the cost of bleached pulp by only 2%, while significantly improving the quality of the pulp, which excludes material costs continued use of cellulose due to the lack of problems with harmful resin. Under the proposed multistage bleaching can be used sulfite pulp obtained by cooking wood vysokoporistyh species: aspen, birch and pine.

The present invention is illustrated by the following examples:

Example 1. Method a multi-stage bleaching of sulfite pulp is as follows:

mass sulfite pulp, characterizing the I following quality indicators:

the Kappa number- 27
the content of resins and fatsa 1.5%
breaking length, m- 9100
resistance:
- fracture, CDP- 1500
- tearing, mn- 480
- punching shear, kPa- 420

bleach according to the scheme: X-S-G-G-K;

- stage be carried out in the presence of detergent VIC-1 in the amount of 0.3% by weight of absolutely dry pulp;

- stage hypochlorite bleaching in weight enter the UMC-1 aqueous mixture of ethoxylated fatty alcohols with a density of 0.98-1.1 g/cm3in the amount of 0.04% by weight of absolutely dry pulp;

- at the stage of kislovka in the mass of the injected aqueous solution of Quaternary polyammonium compounds AFC-2 in the amount of 0.04% by weight of absolutely dry pulp.

The resulting mass is washed and determine the quality of the resulting bleached sulfite pulp by standard methods.

Indicators of quality of bleached sulfite pulp in the table.

Used in the bleaching of sulfite pulp get cooking wood vysokoporistyh species (aspen, birch and pine) at pH boiling solution of 2,3-2,8, the concentration of SO2the 4.5-5.5% and a temperature of VA is key 153-156° C.

Example 2. Method a multi-stage bleaching of sulfite pulp is done according to the scheme: G-S-G-K. using sulfite pulp quality characteristics as in example 1:

- stage hypochlorite bleaching in the mass of the injected aqueous mixture of ethoxylated fatty alcohols as in example 1, in the amount of 0.08% by weight of absolutely dry pulp;

- at the stage be injected detergent VIC-1 in an amount of 0.1% of the mass of absolutely dry pulp;

- at the stage of kislovka enter AFC-2, as in example 1, in the amount of 0.08% by weight of absolutely dry pulp.

The resulting mass is washed and define the indicators of quality bleached pulp, which is shown in the table.

Used in the bleaching of sulfite pulp receive, as in example 1.

Example 3 (the prototype).

Sulphite pulp from a mixture of spruce, pine and birch, obtained as in example 1, bleach scheme G-G-K. In the second stage G in weight enter the waste sodium hypochlorite production KSC-1 in the amount of 0.005% by weight of absolutely dry pulp at a pH of 7.3 within 60 minutes After kislovka mass is washed. Indicators of quality bleached pulp are shown in table.

As can be seen from the table, the proposed method in comparison with the known increases whiteness and the mechanical strength of the bleached pulp and the reduction of tar is fat in cellulose.

Table
Indicators of quality bleached pulpExamples
12Prototype
White, %88,087,586,6
The tar and fat, %0,170,100,38
Mechanical strength:
- breaking length, m820085006800
- resistance:
fracture, CDP12001250700
punching shear, kPa370390290

Method a multi-stage bleaching of sulfite pulp, including the treatment of pulp with a solution of sodium hypochlorite in the presence of chemical additives, bucking pulp and kislovka, characterized in that as chemical additives on the processing stage of the pulp with sodium hypochlorite solution using an aqueous mixture of ethoxylated fatty alcohols with a density of 0.99-1.1 g/cm3in the amount of 0.04 to 0.08% from the assy absolutely dry pulp, bucking pulp is carried out in the presence of detergent VIC-1 in the amount of 0.1-0.3% of the mass of absolutely dry pulp, and kislovka are in the presence of an aqueous solution of Quaternary polyammonium compounds AFC-2 in the amount of 0.04 to 0.08% by weight of absolutely dry pulp.



 

Same patents:

FIELD: paper-and-pulp industry.

SUBSTANCE: invention is designed for use in production of bleached sulfite cellulose with reduced level of resins and fats for manufacturing paper and cardboard in multistep bleaching processes. Process according to invention comprises treatment of pulp with sodium hypochlorite solution in presence of chemical additive, bucking and souring of pulp, sad chemical additive being aqueous mixture of ethoxylated fatty alcohols having density 0.99-1.1 g/cm3 in amount 0.04-0.08% of the weight of absolutely dry cellulose. Bucking of pulp is carried out in presence of detergent named VIK-1 used in amount 0.1-0.3% of the weight of absolutely dry cellulose. Souring is carried out in presence of aqueous solution of quaternary polyammonium compound (BZK-2) used in amount 0.4-0.8% of the weight of absolutely dry cellulose.

EFFECT: reduced gumminess of bleached sulfite cellulose and enhanced whiteness at the same cost.

1 tbl, 3 ex

FIELD: textiles; paper.

SUBSTANCE: method refers to production of pulp from flax raw material and can be used in the paper-pulp industry for producing of pulp for chemical processing as well as for example of cotton wool, paper and cardboad. The method is realised by means of consequent simultaneous tillage and purification of flax-cuke or flax straw, washing and cutting of the material. Then it is soaked, processed in a thermochemical way, washed through and bleached. Then it is washed again, wrung and dried. Following thermomechanic processing of the pulp containing material it is possible to perform maturation in the alkaline solution.

EFFECT: efficiency increase of method of producing of pulp from flax raw material with high degree of chaff.

2 cl, 1 tbl, 12 ex

FIELD: textile fabrics, paper.

SUBSTANCE: method is related to bleaching of hardwood sulphate pulp and may be used in pulp and paper industry for production of fibrous semi-finished products for production of printing types of paper. Suggested method is realised in the following manner. Unbleached hardwood sulphate pulp is disintegrated in water, then squeezed, placed into bleaching bath and delignificated by sodium hypochlorite with its consumption of 3% (in units of active chlorine) from mass of absolutely dry fiber. Then cellulose mass is flushed by water. Then double-stage bleaching of cellulose is carried out by sodium chlorite in acid medium with intermediate alkaline extraction. At the first stage of bleaching sodium chlorite consumption makes 1.5-2.5% (in units of active chlorine), and at the second stage of bleaching it makes 0.4-0.5% (in units of active chlorine) from mass of absolutely dry cellulose. After the first stage of bleaching by sodium chlorite mass is flushed by water and exposed either to oxidising alkaline treatment in the presence of hydrogen peroxide at its expenditure of 0.5%, expenditure of sodium hydroxide of 2.0% from mass of absolutely dry fiber, or alkaline treatment with hydrogen peroxide at its expenditure of 1.0%, expenditure of sodium hydroxide of 0.5%, sodium silicate - 3.0% from mass of absolutely dry fiber. After alkaline extraction cellulose is flushed, and the second stage of bleaching by sodium chlorite is carried out. Afterwards mass is flushed with water, and its acid treatment is carried out with hydrochloric acid.

EFFECT: improved quality of bleached cellulose, enhanced efficiency of process and ecological safety.

1 tbl, 6 ex

FIELD: textile, paper.

SUBSTANCE: procedure refers to production of wood pulp and can be implemented in pulp-and-paper industry. The procedure consists in whitening fibres of sulphate pulp with a whitening agent on base of chlorine and in washing whitened fibres of sulphate pulp. Upon washing fibres of sulphate pulp are subject to interaction with at least one optic whitener before mixing ponds. Interacting is carried out in solution at pH from 3.5 to 8.0 and temperature from 60 to 80C during 0.5-6 hours. The invention also refers to wood pulp produced by the said procedure.

EFFECT: increased whiteness and optic brightness of paper at decreased utilisation of optic whitener.

22 cl, 11 dwg, 11 tbl, 7 ex

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