SU1285093A1 - Method of producing pulp for making electrically insulating paper grades - Google Patents

Abstract

The invention relates to a method for producing cellulose for the manufacture of electrical insulating paper types and improves the quality of cellulose by increasing the content of oi-cellulose therein. The method consists in the fact that after preliminary hydrolysis of the wood phase in the vapor phase, boiling is carried out in an alkaline sulfide-containing solution. As the sulfide-containing solution, the following solution is used, containing, g of sulfur / l: sodium sulfide 4-12; sodium polysulfide 4-12, sodium polysulfate 3-10. This method allows to obtain high-quality cellulose with a content of 93-94% about -cellulose. 1 tab.

Description

The invention relates to the production of pulp and is intended for use in the pulp and paper industry in the production of pulp for electrical insulation paper, in particular for capacitor paper.

The purpose of the invention is to increase the content of oi -cellulose in the target product.

According to the proposed method for producing cellulose, which includes the preliminary hydrolysis of wood raw material in the vapor phase and subsequent boiling with an alkaline sulfide-containing solution, a solution containing, g of sulfur / l: sodium sulfide () A-12 is used as the alkaline sulfide-containing solution; sodium polysulfide (,) 4-12; sodium thiosulfate (, jO) 3-10.

The sodium polysulfide present in the sulphide-containing solution is easily oxidized by the oxygen contained in the chips already at the stage of impregnation of wood with an alkaline solution according to the scheme:

07

Na, S

+ 2NaOH +

H, 0

, +

as a result of the consumption of oxygen, the possibility of its influence on the process of alkaline destructing of cellulose is excluded. This effect begins to manifest itself at a concentration of sodium polysulfide of 4 g sulfur / l and higher, reaching a maximum value at a concentration (NajS.) In an alkaline sulfide-containing solution of 7-9 g sulfur / 40. An increase in polysulphide sodium in an alkaline solution of more than 12 g of sulfur / l leads to a decrease in the content of α-cellulose in the target product and the viscosity index of the copper cell resulting from the oxidative stabilization of tree hemicellulose in the process of alkaline destruction.

Example 1 (known method), Q A wood chips (20 tons in terms of absolutely dry weight) with a humidity of 45-50% are loaded into a 110 m boiling pot, then into the boiler

Example 4, Steam treatment and the prehydrolysis stage are carried out as in Example 1. Then, the calculated amount of alkaline sulfide-containing solution (40-42 m of oxygen-catalytically oxidized oxygen of white liquor) is poured into the cooking apparatus. l: 12, Na.2S 4, Na, S.03 3, Got water with a temperature of 20-90 ° C. The cooking process is carried out at 16043 ° C to

in the volume of 10–12 m, saturated parts of Kappa units are fed to the lower and upper degrees of cellulose delignification of 224 parts of the boiler. The finished pulp is flushed, the temperature in the apparatus is added, sorted, sour, cast.

SO with the simultaneous removal through and dried on the press Pat.

0

five

0

five

upper neck of the steam-air mixture boiler. After the chips are treated with steam at atmospheric pressure, the cooking vessel of the digester is closed and the contents of the boiler are heated with live steam to 150T2 ° C. After being heated at this temperature for 60 minutes, the calculated amount of the alkaline sulfide-containing solution (40-42 m of white liquor containing 16-18 g of sulfur / l) is poured into the cooking apparatus and cooked at 160 Hz: 3 C to the degree of delignification of cellulose units. Kappa. The finished pulp is washed, sorted, sour, cast and dried at the press press.

Example 2 Steam and pre-hydrolysis are treated as in Example 1. Then, a calculated amount of an alkaline sulfide-containing solution (40-42 m of oxygenated white liquor) oxygenated with oxygen is poured into the cooking apparatus.

g sulfur / l: Ka, I 4, 12,

,,

0

0 5 i

3. The cooking process is carried out at 160 ° C to the degree of delignification of cellulose unit Kapp. The finished pulp is washed, sorted, sour, crushed and cypiaT at the press press.

PRI me R 3. The treatment of wood chips with steam and the prehydrolysis stage is carried out as in Example I. Then, the calculated amount of alkaline sulfide-containing solution (40-42 m of oxygen-catalytically oxygenated air of white liquor) is poured into the cooking apparatus. / l: 6, 8,, jO, 5. The cooking process is carried out at 160 ± 3 ° C to a degree of delignification of cellulose 22 ± 3 units, Kappa. The finished pulp is washed, sorted, sour, melted

watered and dried in a press press.

i

Example 4, Steam treatment and the prehydrolysis stage are carried out as in Example 1. Then, the calculated amount of an alkaline sulfide-containing solution (40-42 m of oxygen-white oxygen catalytically air) is poured into the cooking apparatus. / l: 12, Na.2S 4, Na, S.03 3, the cooking process is carried out at 16043 ° C to

3: 1285093 4

Quality indicators of cellulose, in the proposed methods (examples 2, 3

obtained by the known (example 1)

and a) are presented in the table.

The yield of pulp from wood,%

Delignification degree, units Kappa

The content of OH cellulose,%

Viscosity of 0.8% copper ammonium solution, MPa-s

Breaking length, m

Claims (1)

A comparative analysis of the data presented in the table shows that the proposed method provides the possibility of obtaining high quality; pulp with an increased 93-94% content of cellulose content intended for the production of active filler capacitor papers with high electrical strength and low dielectric losses. Invention Formula The method of producing cellulose for the manufacture of electrical insulating fibers, 39 24.7 91.5 68 85 95 90 7800 7900 7700 7800 : Dov paper, including a previewer 25 thirty 35 hydrolysis of wood raw material in the vapor phase and subsequent cooking in an alkaline sulfide-containing solution, characterized in that, in order to improve the quality of cellulose by increasing its cellulose content, an alkaline sulfide-containing solution is used, containing g of sulfur / l Sodium sulfide 4-12 Polysulfide. rub 4-12 Sodium thiosulfate 3-10