SU834285A1 - Paper pulp production method - Google Patents

Description

The invention relates to the paper industry and can be used in the production of bleached types of cellulose by alkaline methods. Methods are known in which a number of reducing agents and oxidizing agents such as boron sodium hydride, hydrazine, hydroxylamine, anthraquinone and its derivatives, and the like, are used to increase the yield of the target product by stabilizing the carbohydrate part during alkaline cooking of wood. 13 However, the aforementioned additives did not find industrial application due to the high cost of reagents and the scarcity of raw materials used for their production, the unresolved issues of chemical regeneration, difficulties in further chemical processing of cellulose arising from chemical impurities. It is more expedient to use for these purposes products and wastes of wood-chemical production. There is a method in which black liquor, selected in the first cooking period at a temperature of about, containing the maximum amount of non-degraded hemicelluloses, after cooling and possibly stabilizing with sodium borohydride or polysulfide, is used in subsequent alkaline cooking in the amount of 20-30% of the volume throughout the cooking liquid G. However, the low content of carbonyl groups in this liquor (O, 5TO, 8% of the organic part), which have a stabilizing effect on the carbohydrate part of the wood, does not allow to increase the yield of the semifinished product. The mechanical strength of the target product is not high enough. The purpose of the invention is to increase the yield and mechanical strength of cellulose. The goal is achieved by the fact that in the method of producing cellulose by alkaline cooking of the initial cellulose-containing raw material in the presence of an additive of a lignin-containing product of chemical processing of avesina, a water-insoluble oxidized hydrolysis lignin with a carbonyl content of 3-10% is used as a pig-containing product.

Oxidized hydrolysis lignin is taken in the amount of 0.5-2.5% by weight of absolutely dry wood.

Oxidized hydrolysis lignin (OHL) is a high molecular weight, water-insoluble oxidation product of hydrolysis lignin, containing 3-1% of carbonyl groups by weight of the starting lignin, which are determined by a known method.

The use of OHL with a high content of carbonyl groups allows an increase in the yield of the semi-finished product due to the stabilization of the carbohydrate part by oxidation of the reducing end groups, while the mechanical strength indices are higher than those of cellulose obtained by conventional alkaline methods and also using black liquor selected in the first cooking period .

Example 1. In laboratory autoclaves, alkaline cooking (sulphate and soda) of birch and spruce chips is carried out.

In tab. 1 shows the cooking modes

Table 1

3.5

Hydromodule

Alkali consumption,% by weight of absolutely dry wood 16

The final cooking temperature, s

172

Duration of rise to the final temperature, min

Duration of standing

at the final temperature,

min

For each wood species and each type of cooking liquor (white liquor and caustic soda), 3 yeri boiling processes are carried out: still sulphate or soda boiling; according to a well-known method with the addition to each autoclave of 30% of the volume of the whole black liquor added liquid selected in the previous cooking during the period when the temperature in the autoclave

3.5

3.5

23

20

169

172

168

65

65

100

85

bypot loot (this alkali is taken into account when calculating the consumption of alkali for cooking) and according to the proposed method with the addition to the autoclave as a suspension in the cooking liquor 1% OGL based on the weight of absolutely dry wood with a carbonyl content of about 7%.

B tab. 2 shows the results of cooking.

cm

s a k

you in

H

Example 2. According to the mode indicated in the table. 1, sulphate and soda pulping of spruce shepa with OGL additives is carried out (1% by weight of absolutely dry wood sulphate

on,%

Sulfate-Delignin degree of fication

Natron-Output Cellulon PS,%

I Natron-Delignini Degree

on f.

From tab. 3, it can be seen that with an increase in the carbonyl content of the added OHL, the yield of cellulose and the degree of lignin removal increase.

In comparison with the known method, the increase in yield is 0.4-O, 9% for sulphate cooking and 0.4-1% for soda. Compared to conventional sulphate and soda melts, the yield is increased by O, 7-1.2% and 0.8-1.4%, respectively.

springs) containing different amounts of carbonyl groups.

The results are shown in Table. 3

Table 3

Increasing the content of carbonyl groups in OGL over 10% is technically difficult to implement.

Example 3, Sulfate and soda boiling spruce whisks are carried out with the addition of various amounts (O-5%) of OGL with a carbonyl content of about 7% according to the regime given in tab. 1, (. Stand at the final temperature for soda cooking is reduced by 20 minutes).

In tab. 4 presents the results of cooking.

s e

Yu "

H

with

Yu

Yu

Oj

with rT

h

cm

cm

og

BUT

"G

L1 "

with

with

with

with

-ABOUT)

with

Th

° 1 cT

g

WITH

t

"L

01

00

H

with

with t

(M

Claims (2)

with As can be seen from tab. 4, an increase in the amount of added OHL from 0.5 to 2.5% causes an increase in the yield of cellulose without changing the degree of delignification, and with a further increase in the amount of OGL added along with an increase in cellulose release, a noticeable decrease in the degree of lignin removal is observed. The proposed method does not differ technologically from conventional cooking methods, it can be used for both periodic and Henpef iBHbix processes. The advantage of the proposed arrangement is also the possibility of using part of the hydrolytic lignin, usually exported to the tap, and considering that in many enterprises there are cooking and hydrolysis production facilities or they are located geographically close to the use of the invention will bring a significant economic effect. Claim 1. The method of obtaining cellulose by alkaline cooking of the raw pulp-containing raw material in the presence of an additive of a lignin-containing product of chemical processing, wood processing, so that, in order to increase the yield and mechanical strength of cellulose, As a lignin-containing product, water-insoluble, oxidized hydrolysis lignin is used with a carbonate content of 3-10%. 2. The method according to p. 1, about t l and h and s and that the oxidized hydrolysis lignin is taken in an amount of 0.5-2.5% by weight of absolutely dry wood. Sources of information taken into account in the examination of the LHoeton H.-So.dla oicj itive softVHOool Puepinq-ia major pego Process. . paper c-anotdcn, 1977, NOe 78, No. 10, 19-24. 2.Di6eeiis., Moreus S.-l. Ribr-P (for vui-tfi Qeci cuftd-fcion of Coo-kinql t or Con annuncf hem-seeeeubose. Svenak Papersti (1968, No. 15, p. 5O9 (prototype).