JPS59137591A - Bleaching of lignocellulose substance - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a method for bleaching lignocellulosic materials.

PRIOR ART In order to use lignocellulosic materials in many applications, it is necessary to bleach the pulp obtained by chemical or mechanical action. Unless kraft pulp is used for applications that do not require whiteness, such as packaging materials,
Bleaching is performed using bleaching agents and bleaching aids such as chlorine, hypochlorite (hypo), chlorine dioxide, oxygen, hydrogen peroxide, and caustic soda to remove residual lignin, etc., which is the cause of coloration in unbleached pulp. There is a need to.

When bleaching chemical pulp that requires strength, in order to maintain the strength of the pulp fiber itself, avoid one-step static bleaching to minimize the effect on the decomposition of carbohydrates (cellulose, etc.). Multi-stage bleaching, in which the bleaching agent and bleaching conditions are mildly changed, is commonly used.

Usually, the lignin is first chlorinated to make it soluble, and then the lignin is dissolved and extracted using an alkali over fire. Thereafter, a small amount of remaining lignin is further decomposed and removed using hypochlorite, chlorine dioxide, etc. to obtain a pulp with high whiteness.

This bleaching process (sequence) is expressed as (C) for chlorine treatment, (K) for alkaline treatment, (6) for hypochlorous acid treatment, (D) for chlorine dioxide treatment, and (ψ) for hydrogen peroxide treatment.
0-B-H-F4-D, 0-IC-D-E-D, 0-B-H-F4-D, 0-IC-D-E-D, 0-B-H-F4-D, 0-IC-D-E-D, 0-B-H-F4-D, 0-IC-D-E-D, according to the order of bleach and/or bleach aid used.
-11! - It is carried out in multiple bleaching stages such as H-D-P.

However, in the conventional method of using chlorine-based bleaching chemicals, the combustion recovery method cannot be used because the bleaching liquid contains chlorine ions. This is the reality.

In the oxygen bleaching method developed in recent years, the bleaching waste liquid can be recycled as a washing liquid for the pulp after cooking, and finally be burned and recovered together with the cooking waste liquid [Japanese Patent Application Laid-open No. 47-5202 (
Corresponding to U.S. Pat.
(Corresponding to Specification No. 73) j1 Currently, many oxygen bleaching devices are in operation in the world's major pulp and paper producing countries, including Japan. In the oxygen bleaching method, the bulb after cooking is immersed in a relatively low concentration alkaline solution, the solution is squeezed to increase the concentration of the bulb, it is loosened well, and oxygen is forced into a reactor under heating and pressure. This method oxidizes and decomposes residual lignin, resin, etc. and solubilizes it with alkali to bleach the pulp (The
Bleaching of Pu1p,, P
159-209, TappiPress 1979
). The degree of this oxidative decomposition reaction is mainly proportional to the temperature and oxygen pressure during bleaching, and the higher the temperature and the higher the drag pressure, the more convenient the reaction is.

However, the drawback of this method is that although the bleaching effect improves when the oxidation conditions are strengthened, cellulose etc. partially depolymerize.
This will result in a decrease in the mechanical properties of the pulp. To compensate for the drawbacks of oxygen bleaching, a protective agent was developed and
Magnesium carbonate, alkali metal Inorganic salts such as borates, titanium dioxide, silica, alkali metal silicates, and alkaline earth metal silicates are disclosed in Japanese Patent Publication No. 47-9203 (U.S. Pat. No. 3+652°386) as magnesium complex salts. It has been proposed that triethanolamine salt is effective, and JP-A-48-9370 and JP-A-49-133601 (corresponding to U.S. Pat. No. 3,951,732) have proposed that triethanolamine salt is effective. It has been shown that there is. Triethanolamine salt is more completely soluble in water than magnesium salt, so it is effective as a protective agent for the depolymerization of cellulose, etc. However, the presence of iron ions in the suspension of bleaching valves It has the disadvantage that it forms an iron ion complex compound and promotes the depolymerization of cellulose etc. due to its catalytic effect, thereby significantly reducing the viscosity of the pulp.

A method of adding a cyclic keto compound, that is, a quinone compound in the alkaline oxygen bleaching method of lignocellulosic materials is disclosed in JP-A-5J-109303 and JP-A-Sho 51-
No. 119801 (corresponding to Canadian Patent No. 1088261), but the purpose of these inventions is to recover the yield loss caused by oxygen bleaching by adding a quinone compound. , it is not intended to synergistically improve the whiteness of the bulb.

The use of peroxide as an oxygen bleach accelerator in the alkaline oxygen bleaching method for lignocellulosic materials is disclosed in Japanese Patent Publication No. 47-9204 (U.S. Pat. No. 3,694,309).
No. 3.719.55 '2
specification, JP-A-52-77202 and 1982
International Sulfite Pulp
ingConference (Toronto.

Canada) Preprint P 143-1
The proposal was rejected in 48. This method of using peroxide and oxygen in combination can provide sufficient whiteness even if the lignocellulosic material is in contact with oxygen for a short time, and compared to the conventional method when comparing the chromaticity over a given day, The degree of depolymerization is small and pulp with high viscosity can be produced. Moreover, the combined oxygen peroxide bleaching method is effective at low oxygen pressure, and does not necessarily require the pressure-resistant container normally used for oxygen bleaching. There are advantages to not doing so.

However, Mizumoto Akihashi et al. investigated multifaceted bleaching methods using oxygen and peroxide, and found that even at low oxygen pressures, this bleaching method achieves the same whiteness as oxygen bleaching methods that increase oxygen pressure due to the whitening-enhancing effect of peroxide. However, this reaction promotion effect has no selectivity and significantly accelerates the depolymerization reaction of cellulose, etc. Under the same oxygen pressure, the kappa number decreases and the yield The disadvantage is that the rate also decreases. Therefore, it has been found that in order to maintain the yield, the oxygen pressure must be further reduced, and as a result, the advantage of increased whiteness disappears.

(Object of the invention) The present invention was made to solve the above-mentioned drawbacks of the bleaching method in combination with oxygen peroxide. It is to provide.

Still another object is to provide a high-strength bleached pulp, a still further object is to provide a low-pressure method of bleaching that does not necessarily require a pressure vessel, and a still further object is to provide a bleaching method that does not necessarily require a pressure vessel.
It is to provide a bleaching method with a low D load, and other objects will become clear from the description below.

The present invention relates to a method for bleaching lignocellulosic materials, characterized in that the cellulosic materials are treated in the presence of oxygen, peroxides and cyclic keto compounds and/or cyclic amino compounds in the presence of an alkaline medium.

Next, the elements constituting the present invention will be explained in detail.

Peroxides used in the bleaching system of the present invention include hydrogen peroxide, sodium peroxide, peracetic acid, t-butyl peroxide,
m-chlorobenshade, cumene hydroperoxide,
Known peroxides such as tetrahydrofuran hydroperoxide can be used. Also, compounds that react with oxygen in the bleaching system to form so-called "in situ" peroxides, such as tetrahydrone (converted to α-tetrahydrofuran hydroperoxide), cumene (converted to cumene hydroperoxide), acetaldehyde (converted to cumene hydroperoxide), Chemicals such as (converts to peracetic acid) can also be used.

Although the effects of the fundamental invention can be exhibited at a high addition rate of peroxide to pulp, it is preferably from 01% to pulp weight.
It is about 1α0chi (H202 conversion), but more preferably 1.0chi to 5.0chi.

As the oxygen used in the bleaching system of the present invention, both oxygen and oxygen-enriched air can be used, but oxygen gas can be used if the volume of the reaction vessel, pressurization, and reaction efficiency are taken into consideration. It is preferable to do so.

To maximize the effects of the present invention, high pressure (10 to 9/C
(m2 or more), the effect is greater when the oxygen pressure is lower, preferably IK17cm2~10K
ylon", more preferably 1 to 7/crn2 to 5Kf
/m12.

Therefore, since the reaction can be carried out at relatively low pressure, there is no need for conventional high-pressure oxygen bleaching equipment, and both vertical and horizontal reactors can be used. , Alui may inject oxygen into the mixer where the pulp is mixed with peroxide.

The cyclic keto compounds or cyclic amine compounds used in the bleaching system of the present invention include the following. Examples of the cyclic keto compounds include benzoquinone, naphthoquinone, anthraquinone, anthrone, 7-enanthrenequinone, and alkyls of the quinone compounds. , amino and hydroxy derivatives, hydro derivatives of said compounds and their tautomers are preferred, and also the group consisting of unsubstituted and lower alkyl substituted Diels-Alder reaction adducts of naphthoquinones and benzoquinones. It can be appropriately selected from 9,10-diketohydroanthracene or 9,10-dioxyhydroanthracene-based compounds selected from.

9.10-diketohydroanthracene compounds include 1.4.4a, 9a-tetrahydro-9,10-diketoanthracene, 1.4.4a, 9a to 5.8, 1
Oa-octahydro-9,10-diketoanthracene and 'X,4-dioxy-9,10-diketoanthracene are suitable. Examples of 9,10-dioxyhydroanthracene-based compounds include 1,4-dihydro-9゜10-dioxyanthracene, 1.4.5.8-tetrahydro-
9,10-dioxyanthracene, 1°4, 5.8.8
a, 10a-hexahydro-9,10-dioxyanthracene or their sodium salts are suitable.

Examples of the cyclic amino compound (nitrogen-containing heterocyclic compound) include phenazine, dihydrophenazine, quinoxaline, and their alkyl, alkoxy, hydroxy, carboxy, and amino derivatives.

The amount of these compounds added to pulp is 0.01 to 5.
The weight is preferably about 102 to 3.0 inches.

The pulp density applicable to the bleaching system of the present invention is from 1 to 65
(weight) is preferably about 5 to 2 degrees, and the pulp density after mixing with meji, alkaline medium or peroxide is 1 to 20
% is preferable.

The bleaching temperature is 70-160℃ and p1 is preferably 80-1.
The temperature is about 50°C. The reaction time is 5 to 120 minutes, preferably 20 to 90 minutes. Reaction pressure is 1-10K
17cm2, preferably 1-5K17cm2.

The alkaline medium used in the bleaching system of the present invention, for example, the alkaline chemicals in aqueous solution 1, include sodium hydroxide, sodium carbonate, sodium bicarbonate, ammonia, Kraft white liquor, oxidized white liquor, green liquor, oxidized green liquor, tetrabo The amount of alkali added to the bulb is 0.5~ in terms of Na2O! A ratio of 1.0 is preferable.

In carrying out the bleaching of the present invention, a peroxide solution containing a cyclic keto compound or a cyclic amino compound may be impregnated into alkaline pulp and then pressurized with oxygen. A peroxide solution may be added to alkaline-maintained pulp containing said compound, and then pressurized with oxygen. Furthermore, oxygen may be applied to alkaline-maintained pulp containing said compound, then The peroxide solution may be added in several portions, and a number of methods can be applied.

The lignocellulosic material to be bleached in the present invention is GP
(groundwood pulp), RMP (IJ finer mechanical pulp), TMP (thermomechanical pulp), cap (
chemical ground pulp), sep (semi-chemical pulp), SP (sulfide pulp), KP (kraft pulp), AP (alkali pulp), waste paper pulp (deinked secondary fiber), etc. Needless to say, it can be applied to any wood pulp. Although the bleaching method of the present invention can be carried out as a standalone bleaching step, it may also be substituted as part of a conventional bleaching sequence.

(Examples of the Invention) Next, the present invention will be described with reference to Examples, but the present invention is not limited thereto in any way.

In the examples set forth below, experiments on oxygen bleaching of lignocellulosic materials and measurements of physical properties of the pulp were carried out by the following procedure unless otherwise indicated.

(Oxygen bleaching experiment) Softwood pulp (Douglas fir) and hardwood pulp (
Beech) 20 ot each (absolutely dry) was placed in a Teflon bag, and a predetermined amount of alkali proportional to the kappa number (kappa number xo, 1%), a predetermined amount of peroxide, and a predetermined amount of a cyclic keto compound and a cyclic amine compound were added. and further increase the pulp density to 15
A predetermined amount of water was added to make the pulp 10%, and after stirring well, the pulp was placed in a rotary autoclave.

The air in the autoclave was replaced with oxygen, and then oxygen was introduced under pressure until a predetermined pressure was reached. The autoclave was heated to raise the temperature from 60° C. to a predetermined temperature in 30 minutes, and the reaction was carried out at the predetermined temperature for a predetermined time.

After the reaction was completed, the sample was taken out and centrifuged and washed.

(Measurement of physical properties of pulp) Regarding the physical properties of pulp, centrifugally dehydrated and washed pulp was measured using PF Emil with Canadian 7 Leeness 6oooCK.
Beaten, TAPPI test method T 205os-71 (:r
xs, pa2o9) weighing 609/
The measurement was performed on a sheet of m2. In addition, each test method was performed according to the following method.

Whiteness J Engineering EI P 8123 The following measurements are based on the paper pulp strength test method (J Engineering gP
8210), Rupture Length J-K SP 8113 Ratio Rupture J-K SP 8112 Ratio Tear J-K 111 P 811S.

Examples 1-2 and Comparative Examples 1-2 Examples 1-2 and Comparative Examples 1-2 show experiments using Douglas fir pulp.

Examples 1 and 2 are hydrogen peroxide as a peroxide and 9,10-anthraquinone (AQ) as a cyclic keto compound (Example 1) and 1.4 to Douglas 7 Arcraft pulp, a softwood with a kappa number of 31.2, respectively. .4a, 9a-
Tetrahydro-9,10-diketoanthracene (THA
Q, ) (Example 2) to caustic powder (vs. pulp xtz
%) to carry out oxygen bleaching.

In the comparative example, caustic soda was added (5%, 12% based on pulp).
) Example of bleaching pulp using only oxygen (Comparative Example 1)
and an example (Comparative Example 2) in which hydrogen peroxide and caustic soda were added to the same pulp to perform oxygen bleaching.

The results are shown in Table 1 below.

Examples 3 to 4 and Comparative Examples 3 to 4 Examples 6 to 4 and Comparative Examples 3 to 4 used Douglas fir pulp with a kappa number of 51.2, and the digestibility (kappa number) of the pulp after oxygen bleaching was the same. This shows an experiment in which the bleaching conditions were changed to achieve the desired results.

Comparative Example 3 was an experiment conducted using only oxygen bleaching without the addition of hydrogen peroxide, and Comparative Example 4 was an experiment in which 1 liter of hydrogen peroxide was added and the holding temperature was lowered by 10°C than in Comparative Example 3. In addition, Example 6 further contains 9,10-anthraquinone (AQ
) was added to α5 to increase the oxygen pressure to 3 K17c as in Comparative Example 4.
This is an experiment conducted by lowering m2, and Example 4 is the same as Example 3.
Instead of AQ, 1.4.4a, 9a-tetrahydro-9,10-diketoanthracene (THAQ) was added to reduce the oxygen pressure by 5 kg/α2 as in Comparative Example 4, and the holding time This is an experiment in which the time was shortened by 5 minutes.

The results are shown in Table 2.

Examples 5 to 6 and Comparative Examples 5 to 6 Examples 5 to 6 and Comparative Examples 5 to 6 show experiments using beech bulb, a hardwood material with a kappa number of 1a5.

Example 5 uses sodium peroxide as the peroxide and anthrone as the cyclic keto compound, and Example 6 uses sodium peroxide as the peroxide and anthraquinone monosulfonic acid sodium (AMS) as the cyclic keto compound. Oxygen bleaching was performed in the same manner as in 1-2.

Comparative Example 5 is an example of oxygen bleaching alone, and Comparative Example 6 is an example of oxygen bleaching in combination with sodium peroxide.

The results are shown in Table 3 below.

Examples 7 to 8 and Comparative Examples 7 to 8 In Examples 7 to 8 and Comparative Examples 7 to 8, beech pulp (kappa number 1a5) was used, and the bleaching conditions were changed to make the digestibility of the pulp the same after oxygen bleaching. The experiment conducted is shown below.

Comparative Example 7 is an example of only oxygen bleaching, and Comparative Example 8 is an example in which 1% of cumene hydroperoxide is added, and the temperature is lowered to 1% compared to Comparative Example 7.
An experiment in which the temperature was lowered by 0°C and the alkali addition rate was decreased by α5 degrees; Example 7 was an experiment in which 1 inch of anthrone was added, the temperature was lowered by 5 degrees Celsius, and the oxygen pressure was lowered by 4 Ky/cm2 than in Comparative Example 7; Example 8 is an experiment in which 1% of 7enazine was added in place of the anthrone in Example 7, and the temperature was lowered by 5° C. and the oxygen pressure was lowered by 4 Kg/cm'' than in Comparative Example 7.

The above results are shown in Table 4.

(Effects of the Invention) As is clear from Tables 1 to 4 above, oxygen bleaching using a combination of a cyclic keto compound, a cyclic amino compound, and a peroxide in an alkaline medium is effective regardless of the difference between softwood and hardwood pulp. In this case, under the same bleaching conditions, the pulp yield can be improved without impairing the bleachability or pulp strength, and the wastewater load is small.

In addition, when the same degree of digestion is achieved, the bleaching temperature, bleaching time, alkali addition rate, and oxygen pressure can be significantly reduced individually or in combination, which is a great advantage in terms of equipment.

Patent applicant: Oji Paper Co., Ltd. Agent Hiroshi Nakamoto Ii Ue Akira

Claims (1)

[Claims] (1) A method for bleaching lignocellulosic material, which comprises treating lignocellulosic material in the presence of oxygen, peroxide, and a cyclic keto compound and/or a cyclic amino compound in the presence of an alkaline medium.