SU1756434A1 - Method of producing cellulose for electrolytic capacitor paper - Google Patents

Abstract

Use: in the pulp and paper industry in the production of pulp for the manufacture of paper, mainly high-absorbing, for electrolytic capacitors. SUMMARY OF THE INVENTION 1 chopped wood raw material is subjected to preliminary water hydrolysis in the vapor phase at 165-170 ° C and a water ratio of 2.0: 1-2.5: 1, sulphate cooking of the prehydrolyzed raw material is carried out, after which the cooking product is acidified in two stages followed by washing. The first stage of an acidic solute is carried out with a solution of orthophosphoric acid or with an aqueous solution of sulfuric anhydride, and the second stage with an aqueous solution of orthophosphoric acid at pH 2.8-5.0. Washing is carried out with production or deionized water. 3 of p. F-ly, 2 tab.

Description

The invention relates to a method for producing cellulose for the manufacture of paper for electrolytic capacitors, is intended for use in the pulp and paper industry and can be used for the manufacture of high-absorbance paper for electrolytic capacitors.

A method is known for producing cellulose for making paper for electrolytic capacitors by sulphate coniferous wood with preliminary hydrolysis. After boiling, the pulp is treated with a solution of SOa in an amount of 2-3% relative to the weight of absolutely dry cellulose fiber, then it is refined with 40-80 sodium hydroxide solution. g / l, subjected to the second acid treatment with a solution of SOa and washed with chemically desalted water.

The disadvantage of this method is that the cellulose obtained is characterized by low mechanical strength and insufficient chemical purity. In addition, the known method does not find practical application because of the high consumption of caustic soda and the problem of utilization (utilization) of waste NaOH solutions from the refining stage.

I (a closest to the technical essence and the achieved result to the proposed is a method of producing cellulose for the production of paper for electrolytic capacitors, including predgidrolizu wood raw material at 155-160 ° C for 1 h at a water ratio of 2: 1, boiling, washing, sour sulfur anhydride in two stages with intermediate washing, additional acidic hydrochloric acid and washing. However, cellulose

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for, obtained by a known method, contains quite a lot of sulphate and chloride ions and does not provide the paper with the required degree of capillary absorption ™. In addition, sulfuric anhydride is used as an acidic pearewja in the process, which leads to contamination of wastewater and air with sulfur compounds, and also worsens the working conditions of the staff. All this requires additional capital expenditures on air and wastewater treatment.

The chain of the invention is to improve the quality of cellulose with one time improvement of working conditions. reducing pollution and simplifying the process.

The goal is achieved by the fact that in the known method of producing cellulose for the manufacture of paper for electrolytic capacitors, which includes preliminary water hydrolysis of wood raw material 8 to the vapor phase, cooking, two-stage souring and washing, preliminary water hydrolysis is carried out at 165-170 ° C, o the second stage kislovka is carried out with an aqueous solution of orthophosphoric acid at pH 2.8-5.0,

In the first stage, the acid is carried out with an aqueous solution of sulfur dioxide or with an aqueous solution of phosphoric acid,

 Washing is carried out with production or deionized water.

Preliminary hydrolysis is carried out at a water ratio from 2.0: 1 to 2.5: 1.

In accordance with the proposed method, cellulose fibers are obtained that are well purified from lignin and hemicelluloses. with a highly developed submicroscopic capillary structure, which contributes to a significant increase in the absorbency of the paper sheet. In the process of sulphate cooking with a preliminary high-temperature prehydrolysis in the vapor phase, cellulose is less subjected to alkaline depolymerization than during cold refining.

The use of orthophosphoric acid at the stage of the kislovka reduces the contamination of cellulose at the stages of the kislovka and washing with sulphate and chloride ions. The presence of orthophosphates in the suspension prevents the adsorption of sulphates and chlorides on cellulose fibers from untreated industrial water. In cellulose, an oxidized phosphoric acid, no accumulation of sulphate ions is observed during its long-term storage, since the possibility of oxidative conversion of sulphites to sulphates under the influence of atmospheric oxygen is completely excluded.

PRI me R 1 Chip from pine wood before sulphate pulping is subjected to preliminary water hydrolysis in the vapor phase at 165 ° C for 1 h and a water ratio of 2.5: 1. Temperature rise to

0 of the specified value is carried out for 1.5 hours. After prehydrolysis, white liquor is poured into the boiler at the rate of 21% active NaaO to the weight of absolutely dry wood. Sulfate cooking is carried out at

5,165 ° C and a water ratio of 4.0.1, up to permachganet pulp stiffness of 90 units and a damping rate of 1 m mass - 2500 pcs. The turnover of the cooking pot is 8.0 hours.

The washed, sorted and condensed cellulose is then subjected to treatment with a solution of orthophosphoric acid in two stages. In the first stage, the acid bath is carried out at a pH of 5.0 and a temperature of 20 ° C for 1 hour. Solution of pyrophosphoric acid

5 is 04% by weight of absolutely dry cellulose. Then the cellulose is washed with production water of usual quality, concentrated and then in the second stage is treated with a solution of phosphoric acid.

0 acid in an amount of 1.2% by weight of absolutely dry cellulose, which provides a pH of 2.8 at 20 ° C for 1 hour. After the acid, the pulp is washed with industrial water until the pH is 6.5. The outflow of water also leads to industrial water.

Example 2. Cellulose obtained by sulphate cooking with prehydrolysis in the vapor phase with process parameters set forth in example 1, was washed, sorted and thickened, and processed at the first stage of a sour solution with an orthophosphoric acid solution in an amount of 1.2% by weight of absolutely dry cellulose provided The pH of the medium is 2.8 at a temperature of 20 ° C for 1 hour. Then the cellulose is washed with industrial water of usual quality and then, in the second stage, is treated with a solution of phosphorus

0 acid in the amount of 0.6% by weight of absolutely dry cellulose, which ensures the pH of the medium is 4.5 at a temperature of 15 ° C for 1 hour. After the acid, the cellulose is washed with deionized water until the pH of the medium 5.8.

5 Cellulose reflux is also carried out on dsionized water,

Example 3. Chip from pine wood before sulphate cooking is subjected to preliminary water hydrolysis (water ratio 2.0: 1) in the vapor phase at 170 ° C

for 1 hour. Sulfate cooking of pre-hydrolyzed chips is carried out with the parameters set forth in example 1.

The washed, sorted and condensed cellulose is then first treated in the first stage of a souring with an aqueous solution of sulfuric anhydride at a rate of 0.9% by weight of absolutely dry cellulose at a pH of 3.5 and a temperature of 10 ° C for 0.5 h. After treatment with a solution the sulfuric anhydride, the cellulose is washed with ordinary cassette production water, thickened with 0m, and then in the second stage it is treated with a solution of orthophosphoric acid in an amount of 1.0% by weight of absolutely dry cellulose, which provides a pH of 3.2 at a temperature of 15 ° C After 2 hours of acidification, the pulp is washed with industrial water until the pH is 6.2. Cellulose reflux is also carried out on ordinary quality industrial water.

Example 4. Cellulose obtained by sulphate cooking with prehydrolysis in the vapor phase with the process parameters set forth in example 3, after washing, sorting and thickening, is treated at the first stage of a kislovka with a solution of sulfuric anhydride in an amount of 0.9% by weight of absolutely dry cellulose providing pH of the medium 3.5 at a temperature of 15 ° C for 0.5 h. The pulp washed with industrial water in the second stage is treated with a solution of orthophosphoric acid in an amount of 0.7% by weight of absolutely dry cellulose, providing a pH of 4.3 at temperature of 15 ° C for 1 h

After the second acid stage, the cellulose is washed with deionized water until the pH of the medium is 6.0. Cellulose reflux is also conducted on deionized water.

Example 5 (known) Before sulphate pulping, pine wood chips are subjected to preliminary water hydrolysis in the vapor phase at 155 ° C for 1 hour and a water ratio of 2,01 The temperature is raised to a predetermined value for 1.5 hours. After prehydrolysis, white liquor is poured into the boiler calculating 22% Na20 by weight of absolutely dry wood. Sulfate welding is carried out at 163 ° C to a permanganate hardness of cellulose of 120 units and a dust content of 1 m2 of a mass of 2500 pcs. The cooking pot turnover was 8.5 h.

The washed, sorted and condensed cellulose is treated with a solution of sulfur dioxide in two steps with a total consumption of 2.0% by weight of absolutely dry cellulose. In the first stage, the kislov process is carried out with the consumption of SOs

1.0% at a pH of 3.5%, temperature 15 ° C for 1 hour. After removal of the reaction products by washing with water of usual quality and thickening, the cellulose is treated with a second solution of sulfuric anhydride at a flow rate of 1.0% at pH 2 ,eight. temperature is 15 ° C for 1 hour. Then the pulp is washed with water, concentrated and treated with an aqueous solution of hydrochloric acid at a rate of 0.1% by weight of absolutely dry pulp for 2.0 hours at 15 ° C. After acidification, the cellulose is washed with production water to a pH of 6.2. For pulping, production is also used.

water

In tab. 1 presents the results of tests of pulp obtained by the proposed and known methods; table 2 - quality indicators of paper made

from cellulose obtained by the proposed method (example 3), and for comparison of the known and the requirements of GOST.

Comparative analysis of the data presented in Table. 1 shows that the cellulose obtained by the proposed method is characterized by high values of a-cellulose content, low values of the mass fraction of ash 0.14-0.16% (according to the known 0.20%), iron 0, 0008-0.0013% (0.0017%), chloride ions 0.0005-0.0006% (0.0008%) and sulfate ions 0.0010-0.0018% (0.0080%).

As can be seen from the table. 2, the invention makes it possible to manufacture an electrolytic paper with capillary absorbency 2 times higher than by a known method. In addition, the invention makes it possible to reduce emissions of highly toxic sulfur dioxide into wastewater and the atmosphere, to improve the working conditions of workers, to enrich wastewater entering biological treatment with orthophosphates,

Claims (4)

1. A method of producing cellulose for the manufacture of paper for electrolytic capacitors, including preliminary water hydrolysis of wood raw material in the vapor phase, cooking, and souring in two stages and washing, characterized in that, in order to improve the quality of cellulose while simultaneously improving working conditions, reducing environmental pollution and simplifying the process, the preliminary aqueous hydrolysis is carried out at 165-170 ° C, and the acidic in the second stage is carried out with an aqueous solution of phosphoric acid acid at pH 2.8-5.0. 2. The method according to claim 1, wherein in the first stage, the Kislovka is carried out with an aqueous solution of sulfurous anhydride or an aqueous solution of orthophosphoric acid. 3. The method according to claim 1, characterized in that the production of waste is carried out. water or deionized water. 4. A method according to claim 1, characterized in that the preliminary hydrolysis is carried out at a water ratio from 2.0: 1 to 2.5: 1. Table 1 table 2