Method of bleaching pulp

 

(57) Abstract:

The method relates to a process of bleaching cellulose and can be used in the production of fibrous materials for various purposes. Cellulose is treated with hydrogen peroxide in alkaline medium in the presence of organic additives. As additives used 2,2-dipyridyl in the amount of 0.02 to 1.0% by weight of the absolutely dry fiber. The proposed method can improve the whiteness of the pulp and expands the range of adjuvants during peroxide bleaching. table 1.

The invention relates to a process of bleaching cellulose and can be used in the production of fibrous materials for various purposes.

There is a method of bleaching lignocellulosic material, which consists in the treatment of pulp with oxygen and peroxides in the presence of cyclic catasetinae and/or amines in alkaline environment [1]. However, the use of gaseous oxygen in the bleaching requires special equipment to create a sufficient concentration of bleaching agent in the reaction mixture.

Closest to the proposed to the technical essence and the achieved effect is a method of bleaching pulp by about the second additive catalytic type - 1,10-phenanthroline [2]. The disadvantage of this method is low efficiency activating action.

The purpose of the invention is the increase of white fibrous material and expansion of the range of activating additives during peroxide bleaching.

This goal is achieved by treating the pulp with hydrogen peroxide in alkaline medium at elevated temperature in the presence of organic additives, which is 2, 2'-dipyridyl in the amount of 0.02 to 1.0% by weight of the absolutely dry.with.) the fiber.

The use of additives 2,2'-dipyridyl you can achieve higher brightness pulp than without additives, which indicates the efficiency of bleaching.

According to the proposed method bleaching subjected namelennoy coniferous sulphate pulp with a hardness of 11 units of Kappa and white 37%. Cook the pulp suspension to a concentration of 10% in a solution containing 3% of hydrogen peroxide and 3% sodium hydroxide (by weight and.with. fiber), and a portion of the additive - 2,2'-dipyridyl (0,02 - 1,0% by weight.with. fiber). Parallel conduct Supervisory experience without additives. The suspension is thoroughly mixed and incubated at 90oC for 30 to 120 minutes and Then spend the following which the fiber is washed with water and prepare a standard casting to define whiteness. Performance white bleached thus cellulose in the table. The results presented in the table indicate the efficiency of peroxide bleaching using additive 2,2'-dipyridyl. Comparison of the action of additives 1,10-phenanthroline and 2,2'-dipyridyl shows that under identical conditions, the proposed Supplement more effective.

The following examples illustrate the invention.

Example 1 (experiments 1, 2). To 1 g and.with. unbleached pulp is poured 10 ml of a solution containing 3% of hydrogen peroxide, 3% sodium hydroxide and 0.02% 2,2'-dipyridyl (all by weight.with. fiber). The suspension is thoroughly mixed, placed in a thermostat and maintained at 90oC within 30 minutes after the mass bleaching leach, then kislovka and washed with water, then cook the casting to define whiteness. Parallel conduct Supervisory experience without the addition of 2,2'-dipyridyl.

Example 2 (experiments 3 - 21). The order of conducting the process of pulp bleaching is the same as in example 1. Differences consisting in the consumption of the proposed additions and the duration of the process presented in the table.

Example 3 (experiments 22, 23). The order of conducting the process is the same as in examples 1, 2. The profile is giving the proposed method can improve the whiteness of the fibrous semi-finished product.

Sources of information

1. Japan's bid N 59-137591, class D 21 C 9/16, 1984.

2. RF patent N 2040617, class D 21 C 9/16, 1995. Bull. N 21.

Method of bleaching cellulose by treatment with hydrogen peroxide in alkaline medium at elevated temperature in the presence of organic additives with subsequent alkali treatment and kislovka, characterized in that the organic additives used 2,2'-dipyridyl as of 0.02 to 1.0% by weight of the absolutely dry fiber.

 

Same patents:

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FIELD: pulp-and-paper industry, in particular method for PULP whitening.

SUBSTANCE: craft pulp mass with concentration of 2.5-5.0 % after oxygen-alkaline treatment is treated with potassium permanganate in consumption of 0.01-0.1 % based on dry cellulose at 40-80°C and pH 1.6-3.0 or with sulfuric acid solution in consumption of 1.0-1.5 % at 90°C for 30 min. In steps II and IV cellulose with concentration of 10 % is treated with hydrogen peroxide in consumption of 2 % based on mass of dry cellulose for 120 min at 80-90°C and pH 9.5-10.5 wherein consumption of sodium alkali and sodium silicate is 1.3 % and 2.5 %, respectively. In step III cellulose is treated with potassium permanganate in consumption of 0.01-0.4 % under step I conditions.

EFFECT: reduced consumption of whitening agents.

1 tbl, 9 ex

FIELD: pulp-and-paper industry, in particular method for pulp whitening.

SUBSTANCE: pulp mass with concentration of 5-10 % after oxygen-alkaline treatment in step I is treated with sulfuric acid in consumption of 5 % based on dry cellulose mass and pH 2.6-3.0. In step II peroxide treatment is carried out in alkali consumption of 1.0-1.3 % based on dry cellulose mass, and in step III pulp is treated with chlorine dioxide in consumption of 1.0-1.6 % based on dry cellulose mass at 70°C.

EFFECT: pulp with increased whiteness.

1 tbl, 17 ex

FIELD: pulp-and-paper industry.

SUBSTANCE: unbleached sulfate cellulose obtained from hardwood is subjected oxygen-alkali delignification, after which treated with chlorine dioxide in presence of oxyethylidenediphosphonic acid and then consecutively hydrogen peroxide and chlorine dioxide solutions. Process may be used in production of bleached fibrous intermediates.

EFFECT: increased whiteness and strength characteristics of cellulose and improved environmental safety of bleaching process.

2 cl, 1 tbl

FIELD: paper-and-pulp industry.

SUBSTANCE: cellulose delignification process comprises alkali treatment, delignification with hydrogen peroxide with sodium hydroxide and sodium silicate additive, and acid treatment. Alkali treatment consumes 0.5% hydrogen peroxide and 2.0% sodium hydroxide based on the weight of absolutely dry cellulose and is conducted for 2.0-2.5 h at 60-90°C. Acid treatment of delignified product is accomplished with aqueous hydrochloric acid, which is consumed in amount 1.0% based on the weight of absolutely dry fibers, while treatment is conducted for 30-60 min at ambient temperature.

EFFECT: enhanced economical efficiency without loss cellulose characteristics.

2 tbl, 11 ex

FIELD: textile, paper.

SUBSTANCE: method is referred to bleached wood pulp production from hardwood chips for their further use in different compositions for paper and cardboard production. Chipped wood is impregnated with alkali solution of sodium sulfite. Spent impregnating solution is then removed. Chipped wood is milled in two stages. In between components are treated by alkali solution of hydrogen peroxide at weight concentration 14-18% and final pH=9.5-10.0. Following the second stage of milling, pulp is dissolved to concentration 3.0-5.0% and cured during 30-60 minutes to pH=7.5-8.0. Pulp is chemically treated by alkali solution of hydrogen peroxide between milling stages at 75-85°C during 15-20 minutes.

EFFECT: decrease of chemicals consumption for impregnation and improvement of mechanical and optical properties of target product.

2 cl, 1 tbl, 4 ex

FIELD: paper industry.

SUBSTANCE: cellulose containing material from herbaceous plants is soaked in alkaline solution, washed, bleached, again washed, squeezed and dried. After soaking thermal-mechanical-chemical treatment is carried out in double-auger device, which consists of heated working chamber with impermeable wall and two parallel joined shafts arranged in it. Alternating injection auger and grinding cam tips are installed on shafts. At the same time prior to washing they additionally execute thermal-mechanical-chemical treatment in double-auger device, on shafts of which there are alternating injection and braking auger tips.

EFFECT: invention provides for cost-efficient method of cellulose making.

2 cl, 1 tbl

FIELD: chemistry.

SUBSTANCE: absorbent material is made by treating lignin-cellulose material in the presence of a catalyst from a transition metal with oxidation. The oxidising agent is selected from a group consisting of hydrogen peroxide, hypochlorite, hypochloric acid or any combination thereof. The lignin-cellulose material is treated at pH from approximately 2 to approximately 6. The treated lignin-cellulose material has viscosity equal to or less than approximately 17 cP. The treated lignin-cellulose material is subjected to dry grinding. The dry ground lignin-cellulose treated material is used as an absorbent intermediate layer for making absorbents.

EFFECT: improved bacteria inhibition properties.

2 cl, 17 ex, 16 tbl

FIELD: textile, paper.

SUBSTANCE: method relates to production of mechanical or chemical-mechanical wood pulp applied as raw material for manufacturing of paper or cardboard, and may be used and pulp and paper industry. According to this method wood pulp is exposed to fibrillation. Produced wood pulp is screened to separate wastes from acceptable materials. At the same time wastes are removed in amount of maximum 60% of overall amount of wood pulp. Wastes and acceptable material are bleached separately. Wastes are bleached with the help of peroxide or peroxy acid. After that bleached wastes are mixed with bleached acceptable material. After combination they are exposed to finishing grinding, at the same time amount of consumed energy makes approximately 10-1000 kW-hr/ton. Finishing grinding is carried out at low concentration. Then wood pulp is batched into paper- or cardboard-making machine. Wastes are bleached in alkaline medium.

EFFECT: improved strength of wood pulp and reduction of energy consumed for grinding.

12 cl, 1 dwg, 1 ex

FIELD: chemistry.

SUBSTANCE: method involves treating cellulose with sulphuric acid at the first step after oxygen-alkaline treatment. At the second step, peroxide bleaching is carried out in an alkaline medium in the presence of a stabiliser - magnesium sulphate. The third step involves treating cellulose with chlorine dioxide with its consumption not more than 0.5% for hardwood pulp and with chlorine dioxide consumption of 0.5-0.7% of the weight of absolutely dry cellulose for soft wood pulp. At the fourth step, cellulose is treated with hydrogen peroxide in an alkaline medium.

EFFECT: reduced consumption of chlorine dioxide, reduced corrosion of equipment and high environmental safety of the process.

1 tbl, 7 ex

FIELD: textile, paper.

SUBSTANCE: method is carried out by means of subsequent soaking of cellulose-containing herbal raw materials in alkaline solution, thermomechanical treatment, squeezing, washing, bleaching, squeezing, washing, squeezing and drying, besides, squeezing and washing are done in pulsating centrifuge.

EFFECT: higher yield of cellulose, reduced norms of consumption of initial reagents and water and reduced power inputs.

1 tbl, 3 ex

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