JP2001032187A - Bleaching assistant for cellulose pulp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the conventionally not available improvement of a bleaching degree of a cellulose pulp by using a specific polyalkylene glycol derivative as a bleaching assistant and adding it together with a bleaching agent to the cellulose pulp slurry. SOLUTION: This polyalkylene glycol derivative expressed by the formula: RO(AO)k(PO)m(EO)nH [R is an alkyl and preferably a 6-12C alkyl; AO is ethylene oxide or >=3C alkylene oxide, preferably a polyoxyalkylene obtained by a random copolymerization of propylene oxide; PO is propylene oxide; EO is oxyethylene; (k) is 2-30; (m) is 0-5; (n) is a number of >0 and <=10] as a bleaching assistant and added to a cellulose pulp slurry together with a bleaching agent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a bleaching aid for cellulose pulp and a method for bleaching cellulose pulp.

[0002]

2. Description of the Related Art Cellulose pulp, which is a raw material for paper, has coloring substances such as lignin adhered to the surface or inside of pulp fibers. Therefore, these substances are removed or decomposed and removed to improve whiteness. In order to bleach.
Various bleaching agents are used for bleaching cellulose pulp. For example, chlorine, hypochlorite, oxygen, hydrogen peroxide, chlorine dioxide, and the like have been used, but the most effective bleach is chlorine. However, when chlorine is used as a bleaching agent for cellulose pulp, the load on drainage is large.
Further, chlorine itself is a harmful substance, and has recently been pointed out as a cause of dioxin production. Therefore, it has been strongly required to reduce the amount of chlorine used as much as possible. In order to reduce the amount of chlorine used, it is conceivable to increase the bleaching efficiency of the cellulose pulp by some method or to use a bleaching agent other than chlorine. Oxygen is being used as a bleaching agent for cellulose pulp instead of chlorine. Oxygen is harmless in itself, and the load on drainage is small.However, oxygen has less bleaching power than chlorine, and various efforts have been made to improve the whiteness of cellulose pulp in oxygen bleaching. ing. In particular, with the advance of computerization in offices, the amount of paper consumption is increasing, and papers with high whiteness are now required. Improving the bleaching efficiency of cellulose pulp is urgent.

[0003] For example, Japanese Patent Application Laid-Open No. 5-51889 discloses that in the bleaching of cellulose pulp, the penetration of oxygen as a bleaching agent into pulp is promoted by adding a nonionic surfactant and an ethylenediaminetetraacetate derivative. A technique for improving the bleaching efficiency has been disclosed. JP-A-5-279979 discloses that bleaching efficiency is improved by adding a nonionic surfactant having a specific structure to the bleaching of cellulose pulp to promote the penetration of oxygen as a bleaching agent into the pulp. A technique for causing this to occur is disclosed. JP-A-5-186987 discloses a technique for improving the bleaching efficiency by adding an alkylene oxide adduct of allyl alcohol in the bleaching of cellulose pulp. Patent No. 2,84
No. 1,048 discloses a bleaching aid comprising a polyalkylene glycol derivative obtained by adding ethylene oxide and propylene oxide to a branched alcohol in a block or random manner.

[0004]

However, any of the above-mentioned bleaching aids has insufficient effect of improving the bleaching degree of cellulose pulp. Therefore, the present inventors have studied the compounds of various structures as bleaching aids to further improve the bleaching efficiency and reduce the amount of the bleaching agent, and as a result, a polyalkylene glycol derivative having a specific structure has been obtained. The inventors have found that there is an unprecedented effect of improving the bleaching degree of cellulose pulp, and have completed the present invention.

[0005]

That is, the present invention provides a compound represented by the following general formula (1): RO- (AO) _k- (PO) _m- (EO) _n- H (1) (AO) _k represents a polyoxyalkylene group formed by random copolymerization of ethylene oxide and an alkylene oxide having 3 or more carbon atoms, PO represents an oxypropylene group, and EO represents an oxyethylene group. , K represents a number from 2 to 30, m represents a number from 0 to 5, and n represents a number from 0 to 1
Represents a number less than or equal to 0. ) Is a bleaching aid for cellulose pulp represented by

Further, the present invention relates to a bleaching agent together with the following general formula (1): RO- (AO) _k- (PO) _m- (EO) _n- H (1) (wherein R represents an alkyl group) , (AO) _k represents a polyoxyalkylene group formed by random copolymerization of ethylene oxide and an alkylene oxide having 3 or more carbon atoms, PO represents an oxypropylene group, EO represents an oxyethylene group, and k represents M represents a number from 0 to 5; m represents a number from 0 to 5;
Represents a number less than or equal to 0. This is a method for bleaching cellulose pulp, wherein a bleaching aid for cellulose pulp represented by the formula (1) is added to cellulose pulp.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In the general formula (1), R represents an alkyl group. Examples of the alkyl group include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, secondary butyl, tertiary butyl, pentyl, isopentyl, secondary pentyl, neopentyl, tertiary pentyl, hexyl, secondary hexyl, heptyl, Heptyl, octyl, 2-ethylhexyl, secondary octyl,
Nonyl, secondary nonyl, decyl, secondary decyl, undecyl, secondary undecyl, dodecyl, secondary dodecyl, tridecyl, isotridecyl, secondary tridecyl, tetradecyl, secondary tetradecyl, hexadecyl, secondary hexadecyl, stearyl, icosyl, docosyl, Tetracosyl,
Triacontyl, 2-butyloctyl, 2-butyldecyl, 2-hexyloctyl, 2-hexyldecyl, 2-
Octyldecyl, 2-hexyldodecyl, 2-octyldodecyl, 2-decyltetradecyl, 2-dodecylhexadecyl, 2-hexadecyloctadecyl, 2-tetradecyloctadecyl, monomethyl-branched-isostearyl and the like can be mentioned.

Among them, R represents a group having 6 to 6 carbon atoms.
Since the 12 alkyl groups have excellent penetrating power into cellulose pulp, the most excellent bleaching degree improving effect can be exhibited. Usually, R is a residue obtained by removing a hydroxyl group from an alcohol. These alcohols are industrially derived from natural alcohols derived from natural fats and oils; or Ziegler alcohols produced through a process of polymerizing ethylene by the Ziegler process (main components are linear primary alcohols), and olefins. Oxo alcohols produced by the oxo method of reacting carbon monoxide and hydrogen (the main component is a linear primary alcohol, which also contains a branched primary alcohol);
Manufactured by air oxidation of paraffin, manufactured as a single or mixed synthetic alcohol such as a secondary alcohol in which hydroxyl groups are randomly bonded to other than the terminal of the carbon chain, and any of these alcohols may be used. it can.

In the general formula (1), PO represents an oxypropylene group, EO represents an oxyethylene group,
(AO) _k represents a polyoxyalkylene group formed by random copolymerization of ethylene oxide and an alkylene oxide having 3 or more carbon atoms. Examples of the alkylene oxide having 3 or more carbon atoms include propylene oxide, butylene oxide, long-chain α-olefin oxide, styrene oxide and the like. As the alkylene oxide having 3 or more carbon atoms, propylene oxide is preferable.
When using more than one kind, it is preferable to use propylene oxide as one of them. The polymerization degrees k, m, and n represent the average number of moles of each alkylene oxide. k represents a number of 2 to 30, and preferably 2 to 2
It is 0, more preferably a number of 3 to 15. m represents a number of 0 to 5, preferably 0 to 2. n represents a number of more than 0 and 10 or less, preferably 0.1 to 5.

The compound represented by the general formula (1) can be produced in the same manner as in the case of a general alcohol alkylene oxide adduct. Specifically, first, after ethylene oxide and alkylene oxide having 3 or more carbon atoms are randomly added to an appropriate alcohol by kmole,
If necessary, propylene oxide is added in an amount of mmol. After that, it can be obtained by further adding n moles of ethylene oxide.

The bleaching aid of the present invention can be prepared by selecting a specific oxyalkylene group as represented by the above general formula (1) and a specific oxyalkylene group such as (AO) _k- (PO) _m- (EO) _n. By performing the addition polymerization in order, a superior effect of improving the bleaching degree is exhibited.By using this bleaching aid, more excellent bleaching than when pulp bleaching is performed with the bleach alone is performed. And can reduce the amount of bleach used. The amount of the bleaching aid used in the present invention varies depending on conditions such as the type of the cellulose pulp to be bleached, the bleaching agent to be used, the target whiteness, and the like. 005 to 3% by weight, more preferably about 0.01 to 2% by weight.

The types of cellulose pulp to be bleached include, for example, chemical pulp such as kraft pulp, chemical ground pulp, semi-chemical pulp, sulfite pulp and alkali pulp; groundwood pulp, refiner mechanical pulp, thermomechanical pulp and the like. Mechanical pulp and the like are mentioned, and the bleaching aid of the present invention exerts the effect of improving the degree of bleaching on both wood pulp and non-wood pulp.

The bleaching aid of the present invention exerts an effect of improving the bleaching degree on any bleaching agent. Examples of bleaching agents used for bleaching cellulose pulp include chlorine, hypochlorite, chlorine dioxide, oxygen, ozone, hydrogen peroxide,
Examples include peracetic acid (salt), percarbonate (salt), perboric acid (salt), and the like. Among them, oxygen-based bleaching agents, such as oxygen, ozone, hydrogen peroxide, peracetic acid (salt), percarbonate (salt), and perboric acid (salt), which are desirable from the viewpoint of load on wastewater and safety, etc.
When used together with a bleaching agent such as the above, the effect of improving the bleaching degree is remarkable, and the bleaching aid of the present invention is particularly effective. The amount of the bleaching agent varies greatly depending on the type of bleaching agent, the type of cellulose pulp to be bleached, the target whiteness, the bleaching conditions such as temperature, and the like. 1-20% by weight, more preferably 0.5%
10 to 10% by weight, most preferably 1 to 5% by weight.

The bleaching aid of the present invention is used in the bleaching step of cellulose pulp for other components such as alkalis such as sodium hydroxide, magnesium salts such as magnesium sulfate, chelating agents, defoamers, peroxide stabilizing agents. Agent and the like.

The bleaching aid of the present invention can be used in combination with other surfactants. Other surfactants include, for example, fatty acid soaps, alkyl sulfonates, alkyl benzene sulfonates, higher alcohol sulfates,
Polyoxyethylene alkyl ether sulfate,
Anionic surfactants such as polyoxyethylene alkyl phenyl ether sulfate, dialkyl sulfosuccinate, higher alcohol phosphate, alkyl benzene phosphonate, aliphatic amide phosphonate, and alkyl naphthalene sulfonate formalin condensate; Examples include nonionic surfactants such as polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene alkyl ester, sorbitan alkyl ester, and polyoxyethylene sorbitan alkyl ester. Among these, particularly preferred are polyoxyethylene alkyl ether sulfate, polyoxyethylene alkyl phenyl ether sulfate, dialkyl sulfosuccinate, polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether and the like.

The bleaching of cellulose pulp is generally performed by pulverizing a raw wood or non-wood pulp, digesting the pulp, and adding about 50 to 20 to the obtained cellulose pulp slurry.
A bleaching agent is added at 0 ° C. for bleaching. The bleaching aid of the present invention may be added to the system in this bleaching step, and the cellulose pulp may be during or after the digestion.

The bleaching aid of the present invention has a low concentration of cellulose pulp slurry (10% by weight) in the bleaching step.
Less), medium concentration (10-20% by weight) or high concentration (20%
% By weight) can be used. Among them, an example of the bleaching conditions of the cellulose pulp at a medium concentration is shown below.

(A) In case of oxygen bleaching Pulp concentration: 10 to 15% by weight Oxygen concentration: 10 to 30 kg / pulp t Alkaline medium: 20 to 30 kg / pulp t Magnesium sulfate: 0 to 3 kg / pulp t Processing temperature: 80 to 130 ° C. Processing time: 0.5-2 hours Top internal pressure: 3-6 kg / cm ² G

(B) Ozone bleaching Pulp concentration: 10 to 15% by weight Ozone concentration: 0.1 to 3% by weight Processing temperature: 10 to 80 ° C Processing time: 1 to 60 minutes

(C) In the case of hydrogen peroxide bleaching Pulp concentration: 10 to 20% by weight Hydrogen peroxide concentration: 0.1 to 3% by weight Processing temperature: 50 to 90 ° C Processing time: 1 to 5 hours Before or after the bleaching step, chlorine bleaching with chlorine, hypochlorite, chlorine dioxide or the like may be performed.

[0021]

The present invention will be described more specifically with reference to the following examples. In the following examples, parts and percentages are by weight unless otherwise specified. Unbleached domestic hardwood under the following bleaching conditions using each of the bleaching aids of the present invention products 1 to 10 and comparative products 1 to 3 shown in Table 1 below and oxygen as a bleaching agent as a bleaching aid. The pulp was bleached. In Table 1, the number of moles of the alkylene oxide added is an average number. EO represents an oxyethylene group, PO represents an oxypropylene group, BO represents an oxybutylene group, and SO represents an oxystyrene group. (EO) / (PO) represents random polymerization, and (EO)-(PO) represents block polymerization.

[0022]

[Table 1]

<Bleaching conditions> Pulp: Unbleached pulp of domestic hardwood (Kappa value: 19.
1) Pulp concentration: 13% (in slurry) Oxygen concentration: 1.5% (relative to absolutely dry pulp) Alkaline concentration: 2.0% (calculated as sodium hydroxide NaO ₂ , relative to absolutely dry pulp) Bleaching aid concentration: 0 0.07% (vs. absolutely dry pulp) Reaction temperature: 110 ° C. ± 5 ° C. Reaction pressure: 5.5 kg / cm ² G Processing time: 1 hour Reaction vessel: autoclave After the obtained bleached pulp is sufficiently washed with water After drying, the kappa value, which is an index of the bleaching degree of each pulp, was measured according to JIS-P-8221. Table 2 shows the results.

[0024]

[Table 2]

[0025]

The effect of the present invention is to provide a bleaching aid comprising a polyalkylene glycol derivative having a specific structure and exhibiting an unprecedented effect of improving the bleaching degree of cellulose pulp.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Masatake Hosaka 7-35 Higashiogu, Arakawa-ku, Tokyo Asahi Denka Kogyo Co., Ltd. F-term (reference) 4L055 AD20 BB17 BB18 BB20 EA30 FA05

Claims (3)

[Claims] 1. The following general formula (1): RO— (AO) _k — (PO) _m — (EO) _n —H (1) (wherein R represents an alkyl group and (AO) _k represents ethylene Represents a polyoxyalkylene group formed by random copolymerization of an oxide and an alkylene oxide having 3 or more carbon atoms, PO represents an oxypropylene group, EO represents an oxyethylene group, and k represents a number of 2 to 30. , M is a number from 0 to 5, and n is greater than 0 and 1
Represents a number less than or equal to 0. A bleaching aid for cellulose pulp represented by). 2. The bleaching aid for cellulose pulp according to claim 1, wherein R is an alkyl group having 6 to 12 carbon atoms and the alkylene oxide having 3 or more carbon atoms is propylene oxide. 3. A method for bleaching cellulose pulp, comprising adding the bleaching aid according to claim 1 or 2 together with a bleaching agent to a cellulose pulp slurry.