RU2217539C1 - Method of cellulose production - Google Patents

Abstract

FIELD: pulp and paper industry, production of sulfite cellulose with decreased share of gums and fats. SUBSTANCE: invention presents a method to produce cellulose, that can be used in the wood-pulp and paper industry to produce sulfite cellulose with decreased share of gums and fats. The cellulose-bearing raw materials are exposed to cooking in sulfite cooking liquor at the presence of a surface-active substance of the nonionic type of hydroxyethylated alkylphenols on the basis of terpolymers of propylene of the following formula: C₉H₁₉C₆H₄O(C₂H₄O)_n, where C₉H₁₉ - alkyl radical izonyl, affixed to phenol, predominantly in a para position to a hydroxyl group, "n" - average number of gramme-molecules hydroxyethylene affixed to one mole of alkyl phenols. The surface-active substance is taken in amount of 0.3-0.5 % from the mass of absolutely dry raw materials. EFFECT: effective decrease of the overall and harmful gummosity of cellulose. 2 cl, 2 tbl, 5 ex

Description

 The invention relates to methods for producing cellulose and can be used at the pulp and paper industry in the production of sulfite pulp with a reduced content of resins and fats.

A known method of producing sulfite cellulose, according to which when cooking wood chips with a sulfite solution, an additive is used: anionic surfactant (surfactant) is a mixture of sodium salts of isomeric alkyl sulfonic acids with a chain length of the alkyl radical C ₁₁ -C ₁₈ and cationic surfactant is a mixture of methyldiethylaminomethyl derivatives polyethylene glycol ethers of alkyl phenols, with a total consumption of anionic and cationic surfactants 0.125-0.350% by weight of absolutely dry wood chips (SU 988940, class D 21 C 3/06, 07/21/81.

 The disadvantage of this method is the insufficiently high effect of the degumming of cellulose (40.5-30.6%).

 Closest to the proposed method is a method of producing cellulose by treating cellulose-containing raw materials with a boiling solution based on sulfuric acid salts (sulphite or bisulphite) at elevated temperature and pressure in the presence of a surfactant - a mixture of polyethylene glycol ether of oleic alcohol (trade name Oksanol-O-18) and oxyethylated n-nonylphenol with a branched nonyl radical and a degree of hydroxyethylation of 9-10 (trade name Neonol AF 9-10) when the ratio of these components of the mixture corresponds from 1.0: 1.5 to 1.5: 1.0. The specified surfactant is taken in an amount of 0.4-0.6% by weight of absolutely dry raw materials (SU 1559024, class D 21 C 3/06, 9/08, 28.03.88). This method is selected as a prototype.

 The disadvantages of this method are the low degree of desalting (33.7-30.3%), the relatively high consumption of surfactants (0.4-0.6% of absolutely dry wood chips) used in the cooking of wood, maintaining the rigidity of cellulose at the same level increased consumption of surfactants.

 In pulp and paper production, two concepts are distinguished: total resinity and “harmful” resinity of cellulose. A characteristic feature of a “harmful” resin is its stickiness and ability to aggregate into large particles. The total resinity of cellulose is important in paper production only insofar as it determines the “harmful” resinity, which can give sticky formations that cause production difficulties: deposition of resin on equipment (sortings, pipelines, etc.), contamination of clothes of paper machines, and this in turn, to breakage of the paper web, scrap of paper (tar spots, holes, etc.) and machine downtime due to blowing or washing of paper nets.

 In the known methods there are no studies to reduce the "harmful" resin.

 Signs of the prototype, which are common with the claimed invention, include the cooking of cellulose-containing raw materials with sulfite cooking solution in the presence of a surfactant.

 The objective of the invention is to increase the efficiency of reducing the total and "harmful" resinous cellulose.

The problem is solved due to the fact that in the known method, including the cooking of cellulose-containing raw materials with sulphite cooking liquor, nonionic surfactants are used as additives — ethoxylated alkyl phenols based on propylene trimers, which are a technical mixture of polyethylene glycol ethers of monoalkyl phenols of the following composition:
C ₉ H ₁₉ C ₆ H ₄ O (C ₂ H ₄ O) _n H,
where C ₉ H ₁₉ is an alkyl radical of isonyl attached to phenol mainly in the para position to the hydroxyl group,
n is the average number of moles of oxyethylene attached to one mole of alkyl phenols.

 The specified surfactant is taken in an amount of 0.3-0.5% by weight of absolutely dry raw materials.

 The trade name is Neonol AF 9-12, manufactured according to TU - 2483-077-05766801-98 (n = 12; 9 is the average number of carbon atoms in the alkyl radical).

 Signs that distinguish it from the prototype are the use of one type of surfactant of a nonionic type as an additive (Neonol AF 9-12). Distinctive features in combination with the known ones provide a decrease in the total and “harmful” resin content of cellulose.

 The proposed method for producing cellulose is carried out in the following sequence.

Spruce wood chips are loaded into an autoclave. The cooking solution on a sodium-magnesium base is preheated to 70-75 ^o C, the preparation Neonol AF 9-12 is dissolved in it in an amount of 0.3-0.5% by weight of absolutely dry wood, poured into an autoclave and the pulp is cooked. After cooking, the resulting cellulose is washed with cold water.

 Examples of specific performance.

Example 1. Chips from spruce wood were loaded into an autoclave and poured with a cooking solution on a sodium-magnesium base, which was previously heated to a temperature of 70-75 ° C. Then pulp was cooked according to the following temperature conditions:
- rise in temperature to 115 ^o C - 1.5 hours,
- parking at a temperature of 115 ^o C - 2.0 hours,
- rise in temperature to 160 ^o With - 2.0 hours,
- cooking at a temperature of 160 ^o C - 2.0 hours.

 The hydraulic unit during cooking was 5: 1.

 After cooking, the pulp was washed with cold water.

Examples 2-5. Spruce wood chips were loaded into an autoclave. The cooking solution on a sodium-magnesium base was preheated to a temperature of 70-75 ^o C and the preparation Neonol AF 9-12 was dissolved in it in an amount of 0.3-0.6% by weight of absolutely dry wood. Next, the cooking solution was poured into an autoclave and pulp was cooked according to the temperature regime described in Example 1. After cooking, the resulting pulp was washed with cold water.

 The values of the effectiveness of reducing the total and “harmful” resin content, as well as the effect of Neonol AF 9-12 additive on the yield, stiffness and mechanical strength of cellulose are presented in table. 1 and 2.

 From the data table. Figure 1 shows that the addition of Neonol AF 9-12 in an amount of 0.3-0.6% by weight of absolutely dry wood did not practically affect the pulp yield and contributed to a decrease in the pulp hardness.

 As can be seen from the presented results, the most effective decrease in the total resin content of cellulose occurs according to the proposed method in the presence of Neonol AF 9-12 in the amount of 0.4 and 0.5% by weight of absolutely dry wood (41.6 and 50.4%), while the “harmful” resin content is reduced by 59.4 and 69.0%. An increase in the consumption of surfactants - Neonol AF 9-12 to 0.6% did not lead to a further effective reduction in the mass fraction of the total and "harmful" resin in cellulose.

 The data table. 2 show that the addition of Neonol AF 9-12 during pulping does not impair the mechanical strength of the pulp.

 The proposed method for producing cellulose in comparison with the prototype allows to increase the efficiency of reducing the overall resin content of cellulose (up to 50.4%); to increase the manufacturability of the cooking solution through the use of one type of surfactant; reduce the consumption of surfactants for cooking wood; reduce the rigidity of the pulp, which accordingly leads to a decrease in the duration of pulping. Along with these advantages, the proposed method allows to reduce the "harmful" resinous cellulose up to 69%.

Claims (2)

1. A method of producing cellulose, including cooking a cellulose-containing raw material with a sulfite cooking liquor in the presence of an additive, characterized in that the additive is a non-ionic type surfactant — ethoxylated alkyl phenols based on propylene trimers, which are a technical mixture of polyethylene glycol ethers of monoalkyl phenols of the following composition: C ₉ H ₁₉ C ₆ H ₄ O (C ₂ H ₄ O) _n H, where C ₉ H ₁₉ is an isonyl alkyl radical attached to phenol, mainly in the para position to the hydroxyl group; Zn is the average number of moles of oxyethylene attached to one mole of alkyl phenols. 2. The method according to claim 1, characterized in that the specified surfactant is taken in an amount of 0.3-0.5% by weight of absolutely dry raw materials.

Images