SU988948A1 - Method of preparing paper pulp for making capacitor papper - Google Patents

Description

The invention relates to a method for the preparation of paper pulp for the manufacture of capacitor paper and is intended for use in pulp and paper industry. The current level of capacitor wiring requires a substantial increase in the quality of capacitor paper, both in terms of tgef and dielectric strength. The quality of the capacitor paper is largely determined by the chemical composition and the physicomechanical properties of the semi-finished product. A prerequisite for achieving good electrical characteristics of the paper is the purity of the pulp in terms of mineral composition and organic impurities. Reducing the amount of organic impurities in cellulose gives a decrease in the dielectric loss tangent only in the region of low positive temperatures. In light of the above, special significance for the production of condenser paper, the product acquires cellulose with a high content of (/ -cellulose (92-95% and a minimum ash content of optimal composition). Condenser paper production technology, including pulp dissolving, predresolving, swelling and grinding of paper pulp, is known. - pressing, drying and finishing of paper web.A typical semi-finished product for the production of capacitor paper is sulphate pulp containing d -cellulose 85%, ash 0.25%, pentosan 10%. Known cellulose with a pL-cellulose content of up to 92-95% tl. However, its field of use is limited to the production of electrolytic paper, where grinding is carried out to 0-60% HR.For capacitor paper with improved electrical characteristics, such cellulose cannot be used because it gives a low the degree of fibrillability of the fibers during the grinding of non-existing equipment at the present time cannot be ground to 97-98RS, and consequently, it is impossible to obtain a paper web with a satisfactory structure that provides an acceptable electric ical strength paper-dielectric. A known method of preparing paper pulp for the manufacture of capacitor paper from cellulose with a high content of oi-cellulose, consisting in dissolving, swelling of cellulose in an aqueous solution of oxygen-containing acid selected from the group containing phosphoric, acetic or boric acid, and grinding G2 J. The disadvantage of the described The method consists in the fact that the concentration of acids in waste water, even at its minimum consumption, exceeds the permissible rate (0.1 mg / l). The aim of the invention is to reduce the acid concentration in the wastewater. This goal is achieved in that according to the method of preparing paper stock for the manufacture of capacitor paper, including dissolving the swelling of cellulose in an aqueous solution of oxygen-containing acid selected from the group containing phosphoric, acetic or boric acid, and grinding, according to the invention, swelling of cellulose in aqueous acid solution lead before its dissolution. The difference of the proposed method of preparing paper pulp for producing capacitor paper from the known one is that the operation for pulping pulp in an aqueous solution of oxygen-containing acid is carried out before pulp dissolving, i.e. cellulose in the sheets is swelling. This solution allows for effective cellulose swelling with a significant reduction in acid consumption. If the prototype acid consumption is 0.5-10% by weight of abs. dry fiber at the concentration of the aqueous solution of acid 0, in accordance with the invention, the concentration required for swelling is achieved at an acid consumption of 0.1-0.3% by weight of absolute fiber, i.e. at a tenfold decrease, which ensures a decrease in the concentration of acid in the waste water to 0.016–0, “V mg / l, with a permissible rate of 0.1 mg / l. - An example. Take 70 g of absolute acetic cellulose in the form of a sheet, the content of cL-cellulose is 92. Cellulose is soaked in a 0.03% solution of boric acid (boric acid consumption 0.1% by weight of cellulose). Then it swells in this solution for 16 hours. After swelling, the cellulose is dissolved in a laboratory mesh for 3-5 minutes and placed in a laboratory roll, filled with deionized water to a concentration of 2% and milled. The finished paper pulp has the following indicators Grinding degree, SHR Mass index ADD, dg Fibrillation degree,% pH of the aqueous extract Grinding time, h Castings (paper samples) 10 g / m are made of the obtained pulp voltage, Electric strength, KB / MM Content of e-samples of paper Acid concentration in water, waste with OTLEVb paper samples, mg / l2,5. PRI mme R 2. Take 70 g of absolutely dry cellulose in the form of a stack of sheets, the content of o-cellulose in it is 92%. Cellulose is soaked in P, 03% phosphoric acid solution (consumption of phosphoric acid 0.1% by weight of cellulose). Then it swells in this solution for 16 hours. After swelling, the pulp is dissolved in a laboratory mixer for 3-5 minutes, and placed in a laboratory roll, filled with deionized water to a concentration of 2% and grind. The finished paper pulp has the following indicators: Grinding degree, ShR 97.0 Fibrillation degree,% 92-93 Bulk ADD indicator, dg30.2 pH of water extract Grinding time, h 7 0 From the resulting paper pulp, the castings are pressed (samples of paper Mass .10 g / m Thickness, µm 36, O Density, g / cm 0.67 Breakdown voltage, V77 Electrical strength, KB / MM 21.5 HjP04 content in paper samples Traces Acid concentration in water, about a stroke common low tide: boom samples mg / l - 2.5. EXAMPLE 3: Take 70 g of absolutely dry cellulose in the form of dust sheets, the content of cjt-cellulose 92 The cellulose is soaked in a Qv2% -HOM solution (the consumption of carboxylic acid is 0.5% by weight of cellulose. Then it swells in this solution for 16 h. After swelling, the cellulose is dissolved in a laboratory blender for a minute, the laboratory roll is placed Pour deionized water to concentration and grind. Ready-made paper has the following indicators, milling degree, SR 97.5 Mass index, ADD, dg30.0 Fibrillation level,% 93-9 pH of water extract 5.7 Grinding time, h 7.0 From the resulting paper pulp from the prepared castings (samples of papers Mass 10 g / cm Tol thickness, µm 37.0 Density, g / cm 0.66 Breakdown voltage, H 825 Electric strength, KB / MM 22.3 Content, paper samples Traces Acid concentration in water, waste when the paper samples are poured, mg / l 12.5 PRI M 4. Take 70 g of absolutely dry cellulose in the form of a leaf of a sheet, sbderzhaniya (-cellulose in it 92. Cellulose is soaked in 0, a solution of phosphoric acid, the water ratio is 1: 3 (consumption of phosphoric acid 0, 5% by weight of cellulose). Then it swells in this solution for 16 hours. After swelling, the pulp is dissolved in a laboratory mixer for min. And placed in a laboratory roll, filled with deionized water to a concentration of 2% and milled. The finished paper pulp has the following indicators: Grind degree, SR 97, ADD mass ratio, dg30.1 Fibrillation rate,% 93-9 pH of aqueous extract 5-7 Grinding time7 h Castings are made of the obtained paper pulp (paper samples). Weight 10 g / m Thickness, mkm, 36.0 Density, g / cm 0.66 Breakdown voltage, V792 Electrical strength, KB / MM 22.0 Content in paper samples Traces Acid concentration in water, waste at sample ebb Paper 12.5 The table summarizes the data characterizing the raw materials, the technological parameters of the mass preparation process, the characteristics of the mass, castings and waste water. For comparison, similar information is given on the traditional industrial method (pos. 1) and on the method of pro-. tetipu. The proposed method is not the ledge on the technological parameters and characteristics of the material of the prototype, has the advantages of the acid content in the wastewater.

Table continuation

97.2

30.2

97, 30.1 98.0 31.0

37.0 ohm

5.8 36.0 0.66 81 5.7 21.6 0.67 800 6.6

Continuation of the table

Claims (1)

Claim I A method of preparing paper pulp 40 for the manufacture of condenser paper, comprising dissolving, swelling cellulose in an aqueous solution of an oxygen-containing acid selected from the group consisting of phosphoric, acetic 45 or boric acid, and grinding, characterized in that, in order to reduce the acid concentration 0.0016 0.0080 0/016 0,048 1. The minimum dilution factor in the industrial wastewater K = 55 0.08 2. Minimum dilution ratio 0.0016 when descending into the river K = 3 0.0080 0.016 0,048 0.08 1.6 __________________ in wastewater, cellulose swelling in an aqueous acid solution is carried out before its dissolution.