SU1708977A1 - Method for cellulose bleaching - Google Patents

Abstract

This invention relates to pulp bleaching technology and allows for a reduction in yield loss and improved pulp quality while reducing the consumption of chlorine dioxide. Cellulose is treated in four steps, the first and third of which are carried out by cycloaliphatic hydroperoxide, and the second and fourth steps are carried out with chlorine dioxide. As a cycloaliphatic hydroperoxide, a compound selected from the group containing di-

Description

This invention relates to pulp bleaching methods and can be used in the pulp and paper industry in pulp manufacturing.

Known methods of bleaching cellulose by treating bleaching agents such as chlorine gas, hypochlorites, chloramines, chlorine dioxide.

A known method of bleaching pulp from softwood and hardwood by using simultaneously with various chlorine compounds various inorganic and organic bleaching agents. As bleaching agents, hydrogen peroxides, sodium, barium, sodium perborate, peracetic, and semi-uniform acid are used. supropionic acid, as well as hydroxy- and aminocarboxylic acids. Organic acids having two or more carboxyl groups and one to ten hydroxyl groups are used. The amount of organic bleaching agents added is from 0.1 to 4%.

The disadvantages of this method are the destruction of the structure of the pulp during bleaching and a sharp decrease in its viscosity. In order to reduce cellulose degradation, magnesium complex compounds, such as carbonate, sulfate, hydroxide, and magnesium oxide, are added.

The closest is a method of bleaching cellulose in four steps using organic peroxide compounds, such as cyclic alcohol derivatives: cyclopentyl hydroperox The formula of the invention is a method of bleaching cellulose by treating it in four steps, the first and third of which are cycloaliphatic hydroperoxide, and the second and fourth chlorine dioxide characterized in that, in order to reduce yield losses and improve the quality indicators of cellulose while reducing the consumption of chlorine dioxide, As a cyclo78 aliphatic hydroperoxide, a compound selected from the group containing d- (1-hydroperoxycyclohexyl) -peroxide, di- (1-hydroperoxycyclopentyl) -peroxide is used. 1-hydroxy-1-hydroperoxycyclohexane, 1g11droxy-1-hydroperoxycyclopentane, 1 hydroperoxycyclohexylamini 1-hydroxyperoxycyclopentylamine.

Cellulose before bleaching

 Hydrogen peroxide 408763698365006, 5 and HjOj53

The use of peroxides obtained on the basis of cyclic alcohols

(according to the prototype)

Cyclohexyl hydroperoxide

O-OOH 56 36

Cyclopenyl hydroperoxide

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The use of peroxide containing active oxygen in the cycle

Dicumyl peroxide

CHj pH, / (OOS-OOO-S-CHO) 6526

- dHj CHj 1,2-Dioxa-6en () 5 Cyclohexane-3,6-dione

, 0. 57, 35 62

The use of peroxides, lolumsnii based on the CEESLIC ketsnoye

XI (according to the invention)

Di- (1-hydroxycyclohexyl) -neroxy, / 366010066958672005.0

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t2 1-Hydroxy "roxycyclopentyl-amine

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5 Editor A.Dolinich

Order 410 Circulation: Subscription

VNIIPI State Committee for Inventions and Discoveries at the State Committee on Science and Technology of the USSR 113035. Moscow, Zh-35, Raushsk emb. 4/5

Production and Publishing Combine Patent, Uzhgorod, Gagarin st., 101

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60007.0 (prototype)

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10265100 Compiled by L.Trofimuk Tehred M.MorgentalKorrektor M.Demchik

Claims (3)

SUMMARY OF THE INVENTION A method for bleaching cellulose by treating it in four steps, the first and third of which are carried out by cycloaliphatic hydroperoxide, and the second and fourth chlorine dioxide, characterized in that, in order to reduce yield losses and improve the quality of cellulose while reducing the consumption of chlorine dioxide, as a cyclo 1708977 8 aliphatic hydroperoxide use a compound selected from the group consisting of d- (1-hydroperoxycyclohexyl) peroxide, di- (1-hydroperoxycyclopentyl) peroxide, 1-hydroxy-1-hydroperoxycyclohexane, 1hydroxy-1-hydroperoxycyclohexylamine 1-hydroxyleroxycyclopentylamine. example Bleach Pulp values after the 1st stage of bleaching Pulp values after four stages of bleaching Rigidity Vyazg Belize Viscosity, White, Gap Losses P.E. Delignification,%. bone, mPas on the, % mPas Kaya length, n output _{t ί} I Pulp before bleaching OF 2 '' Hydrogen peroxide Η ₂ 0χ 53 40 87 63 69 83 6500 6.5 Application peroxides obtained. based cyclic alcohols (by prototype) 3 Cyc loge Xi PG idroperoxide O'un 56 36 84 64 70 81 6000 7.0 4 Cyclopene Tyl Hydroperoxide □> 00H 58 Application 34 85 60 ! peroxides containing 72 active 81 oxygen in 5500 the cycle 7.0 (prototype) 5 Dicumyl peroxide 6 1,2-dioxabenz (· ->] cyclohexane-3,6-diO ABOUT 57 35 62 62 The use of peroxides derived from (according to the invention) cyclic ketones Di- (1-hydroperoxy cyclohexyl) -pe- 1-G idroxy-1-hydro 36 60 100 66 95 86 7200 5.0 peroxycyclohexane Qh ° ^H ' Di- (1-hydroperoxyxycyclolentyl) -peroxide 103 64 87 87 7000 4.8 87 7500 5.0, 112 61 110 10 1-hydroxy-1-hydro- leroxycyclopemtan Q-00H 47 47 112 60 109 eleven He is 1-Hydroperoxy- <cyclohexylamim C3g ^UN 46 48 105 63 87 ΝΗ 87 7500 87 7200 5,0 5.2 12 1-Hydroxyperoxycyclopentyl-> vnin 102 65 100 7300 5,0 Editor A. Dolinich Compiled by L. Trofimuk Tehred M. Morgenthal Corrector M. Demchik Order 410 Circulation Subscription VNIIIPI of the State Committee for Inventions and Discoveries at the State Committee for Science and Technology 113035. Moscow, Zh-35, Raushskaya nab., 4/5 Production and Publishing Plant Patent, 101, Gagarin St., Uzhgorod, processing temperature 70 ^u C, duration 60 min, delignification degree after the first stage 37%. Second stage: bleaching with chlorine dioxide, consumption СГГ 1.0%, temperature 70 ° С, duration 180 min., Third stage: bleaching with peroxides based on cyclic alcohols, peroxide consumption 0.8%, stabilizer consumption 0.8%, consumption No. ОН 1%, temperature 70 ° С, duration 180 min. Fourth step: chlorine dioxide bleaching, consumption СГГ 0.6%, processing temperature 70 ° С, duration 180 min. After bleaching, the pulp had a brightness of 81%, a breaking length of 5500-6000 m, chemical losses during bleaching amounted to 7%. Example 3 (in table. No. 5 and 6). For comparison, the cellulose sample of Example 1 was bleached with anhydride-based peroxide in one step (II), according to one embodiment of the prototype. As a bleach used peroxide containing in the cycle of active oxygen-dicumyl perox CH ₃ sn ₃ LED ^ t-0-OCO CH ₃ C11 ₃ and 1,2-dioxabenz [d] cyclohexane-3,6-dione. G After the 1st stage, cellulose had high stiffness and low viscosity. The degree of delignification was only 23%. Further completion according to the D-P-D scheme is impractical. In the following examples, the proposed cyclic ketone bleaches were used. For example, p4 (in the table. Nos. 7 and 8). The cellulose sample of Example 1 was bleached according to the complete P-D-P-D scheme using two pe-based cyclohexane di- (1 hydroperoxycyclohexyl) peroxide - 1-hydroxy-1-hydroxycyclohexane. First stage: peroxide bleaching, consumption 3%, processing temperature 70 ° С, duration 60 min. Second stage: chlorine dioxide bleaching, СIОg consumption 0.6%, temperature 70 ° С, duration 180 min. Third stage: peroxide bleaching, peroxide consumption 0.8%, duration 180 min. oxides on UN Qo-ochr un ^and Q-ooh he Fourth step: chlorine dioxide bleaching, conditions according to example 2. In this and subsequent examples, no stabilizer was used. 5 As a result of bleaching, cellulose with a whiteness of 86-87%, a breaking length of 7000-7200 m, a viscosity of 87.95 mPas was obtained. Chemical losses amounted to 4.8-5.0%. EXAMPLE 5 (in table. Yu No. 9 and 10). The cellulose sample of Example 1 was bleached according to the full PD-PD scheme using peroxides based on cyclopentane 1-hydroxy-1-hydroperoxycyclo pentane G> o-ochr UN UN di- (1-hydroperoxyroxy-pentyl) peroxide. The bleaching conditions of example 4. As a result of bleaching, cellulose with a whiteness of 87%, a breaking length of 7500 m, a viscosity of 109-110 mPas was obtained. Chemical losses amounted to 5%. Example 6 (in the table. GF 11 and 12). The cellulose sample of example 1 was bleached according to the scheme P-D-P-D. Amino peroxides G> UN were used as bleach - 1-hydroperoxycyclopentylamine and NH ₂ <> O0H min. - hydroperoxycyclohexyl bleaching Conditions according to example 4. As a result of bleaching using aminoperoxides, the cellulose quality indicators are at the same level as when using other 4Q cyclic ketone peroxides. The use of organic peroxides on the basis of cyclic ketones provides: a reduction in yield losses of cellulose 45 by 1.0-1.5% compared with known bleaching methods; 35% increase in the brightness of cellulose compared with known methods of bleaching with other peroxides; achievement of a high degree of 50 delignification (55-60%) while maintaining viscosity almost at the initial level; increase in breaking length by 1000-1500 m; reduction of chlorine dioxide consumption by 2-4 kg / t. 55 The method can be carried out at enterprises for the production of pulp using the proposed bleaching. televisions. the preparation of which does not require complex equipment ¹ Foot, heat flow and high energy costs.