JPS6059356B2 - Pulp manufacturing method - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for producing pulp.

More specifically, in a method for producing pulp by cooking lignocellulose material, which is a raw material for pulp, in an alkaline cooking liquor or a cooking liquor containing sulfites, an improved pulp is produced in which a specific compound is present in the cooking liquor. Regarding the manufacturing method. Methods for producing pulp from lignocellulosic materials such as wood include the soda method, which involves cooking with a cooking liquor containing caustic soda or soda carbonate as the main ingredients, and the soda method, which involves cooking with a cooking liquor containing caustic soda and soda sulfide as the main ingredients. There are the Kraft method and the sulfite method, which involves cooking with a cooking liquor containing sulfites as a main component.

In all of these methods, the purpose is to remove lignin from lignocellulosic material by digestion to obtain only cellulose.

However, under normal cooking conditions that allow lignin to be eluted from the lignocellulosic material, the cellulose component is also dissolved, which has the disadvantage that the pulp yield is reduced.
This drawback is particularly noticeable in the soda method, which requires a long cooking time. On the other hand, although the Kraft method has a higher yield than the soda method, it has the drawback of producing foul-smelling mercaptans and hydrogen sulfide, which pollutes the atmosphere. In order to solve these problems, various improvement plans have been proposed in the past.

For example, in the Kraft method, it is known to use an oxidizing agent such as polysulfide (Na2Si) or a reducing agent such as sodium borohydroxide (NaBH4), hydrazine, or hydroxylamine in the cooking liquor; It is unstable in high-temperature cooking processes, requires a large amount of use, and is expensive. Furthermore, these methods also have the problem of bad odor due to sulfur compounds, and are therefore not preferred methods. recent years,
Anthraquinone monosulfonic acid (hereinafter referred to as A) is added to the soda method.
Abbreviated as MS. ) was proposed.
[ZellstOffpapier2l, NO. l. 3
~7 (1972) and East German Patent No. 98549/73]
.

A method has also been proposed in which AMS is used in the first step of the soda oxygen cooking method to improve the bulb yield. (
(U.S. Pat. No. 3,888,727) However, in recent years, in the paper manufacturing industry, which has required an almost completely closed system, the soda method using AMS produces sulfides derived from AMS in the chemical recovery process after cooking. ,
It has the disadvantage that mercaptans and hydrogen sulfide are generated in subsequent steps. After that, a method using an anthraquinone derivative instead of AMS (Japanese Patent Application Laid-open No. 51-43403,
JP-A-52-37803) and a method using a Ziels-Alder adduct of quinones such as naphthoquinone and butadiene (US Pat. No. 4,036,681) have been proposed.

Although anthraquinone compounds do not generate sulfides as described above, they have the disadvantage of being difficult to dissolve in cooking liquor, and therefore cannot be expected to have a cooking effect. In addition, the Ziels-Alder adduct is practically an adduct of industrial 1,4 naphthoquinone and 1,3-butadiene;
- Naphthoquinone contains acidic substances such as phthalic acid and benzoic acid, and when performing the Ziels-Alder reaction without removing these acidic substances, after the reaction, the solvent is separated from the reaction product by distillation etc. When taking out 4,4a,9a-tetrahydroanthraquinone, 1,4,4a,9
The enolization reaction of a-tetrahydroanthraquinone proceeds, and a considerable amount of 1,4-dihydroanthrahydroquinone is produced as a by-product. Since this has a high melting point, it is difficult to extract 1,4,4a,9a-tetrahydroanthraquinone, and it is not possible to obtain an industrially pure product, so that the cooking effect cannot be said to be sufficient. In addition, 1,4-dihydroanthrahydroquinone is extremely unstable as it is oxidized by molecular oxygen in the air, and there are problems in its handling. In view of the above circumstances, the present inventors have conducted various studies with the aim of obtaining an auxiliary agent that improves the cooking effect as a cooking agent, that is, the bulb yield and increases the cooking rate, and has found that dihydroanthraquinones, The present invention was achieved based on the discovery that tetrahydroanthraquinones or their quinhydrone compounds are particularly excellent.

That is, the gist of the present invention is to provide a method for producing a valve by cooking a lignocellulose material in an alkaline cooking liquor or a cooking liquor containing sulfite, in which the cooking liquor has the general formula (1).
or (■) (in the above general formula (1) or (■), R and x are an alkyl group, a hydroxyl group, an alkoxyl group,
Indicates an atom, an amino group, or a hydroxylamino group.

Moreover, m and n indicate the number of substituents and are integers of 0 to 4. ) or tetrahydroanthraquinones or quinhydrone compounds thereof are present. To explain the present invention in detail, the dihydroanthraquinones or tetrahydroanthraquinones represented by the general formula (1) or (■) used in the present invention are a combination of naphthoquinone, benzoquinone or a derivative thereof and butadiene or a derivative thereof. The Ziels-Alder reaction product can then be produced with high purity by oxidizing it while controlling the pH and temperature.

For example, 1,4-naphthoquinone and 1,3-butadiene are usually subjected to a Ziels-Alder reaction in an organic solvent such as benzene. ~1
2 and then air oxidation at a temperature of 70° C. or lower will produce 1,4-dihydroanthraquinone. In this case, if the pH exceeds 12 or the temperature is too high, anthraquinone will be produced as a by-product, which is not preferable. Then, by filtering and washing with water, 1,4-dihydroanthraquinone with good purity can be obtained. Next, the quinhydrone compound is a reaction product obtained, for example, by the Ziels-Alder reaction of 1,4-naphthoquinone and 1,3-butadiene, that is, 1,4,4a,
? - by heating tetrahydroanthraquinone in e.g. acetic acid, an aromatic hydrocarbon in the presence of air, 1,
A quinhydrone compound, which is a molecular compound consisting of 4-dihydroanthraquinone and 1,4-dihydroanthrahydroquinone, is obtained.

Furthermore, dihydroanthraquinones, tetrahydroanthraquinones, or quinhydrone compounds thereof having substituents can be similarly obtained by using butadiene derivatives having corresponding substituents as starting materials for the Ziels-Alder reaction. The dihydroanthraquinones of general formula (1) include 1,4-dihydroanthraquinone and its substituted substances, such as 1-methyl-, 2-methyl-,
Alkyl substituents such as 2,3-dimethyl and 2-ethyl;
Hydroxy-substituted products such as 5-hydroxy; alkoxy-substituted products such as 5-methoxy; amino-substituted products such as 5-amino and 6-amino; and especially 1,4-
Dihydroanthraki, non is preferred.

1,4-dihydroanthraquinone is a yellow crystal and is stable even in air.

Tetrahydroanthraquinones of general formula (■) include 1,4,5,8-tetrahydroanthraquinone and its substituted substances, such as 2,6-1 or 2,7-dimethyl-, 2,3,6,7-tetramethyl, etc. Examples include alkyl-substituted products of, and 1,4,5,8-tetrahydroanthraquinone is particularly preferred. This compound also has yellow crystals and has good storage stability as an industrial product. In addition, examples of quinhydrone compounds include, for example, 1,4-dihydroanthraquinone and 1,4-dihydroanthraquinone of general formula (1), or 1,4,5,8-tetrahydroanthraquinone and 1,4, These include 5,8-tetrahydroanthrahydroquinone and their substituted products, and unlike mere mixtures, these are molecular compounds with hydrogen bonds, so they are extremely stable, and generally have a black-purple color with a metallic luster. It is a crystal.

In the present invention, one or more of the above compounds are added to the cooking liquor. The lignocellulosic materials used as valve raw materials targeted in the present invention include Scots spruce, Sakhalin fir,
Coniferous trees such as fir, hardwoods such as birch, beech, and maple,
Others include straw, bagasse, etc. In order to carry out the method of the present invention, these raw material wood chips are soaked in water for more than ten hours in advance, and then 0.00 of the absolute dry weight of the chips is soaked in water for more than ten hours or more.
5-3, preferably 0.01-1. Bulbing is performed using a cooking liquor to which the compound of the present invention is added in an amount corresponding to the heel weight %.

The composition of the cooking liquor is, for example, 8 to 2 percent effective alkali in the soda method, and 4 to 2 percent effective alkali in the Kraft method.
A cooking liquor composition having a sulfidity of about 10 to 3% by weight is usually used.

The cooking temperature may be the same as in the conventional method, but in the case of the present invention, the cooking temperature can be lower than that without additives,
Also, if the cooking time is the same at the same temperature, the kappa number (
(indicating the residual amount of lignin), the temperature is usually 160 to 200°C for the Sonida method and 140 to 200°C for the Kraft method.
The temperature is about 200°C. According to the present invention, the cooking rate and bulb yield can be improved over conventional methods using AMS or anthraquinones as a cooking aid. Further, the additive of the present invention can be produced industrially stably and easily. Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to the following Examples unless the gist thereof is exceeded.

In addition, in the following examples, % indicates weight percent. Example 1 Coniferous wood chips soaked in water in advance were placed in a rotary stirring autoclave, and the additive of the present invention and a conventionally known additive for comparison were added to a soda cooking liquor containing 16% caustic soda as an effective alkali relative to bone dry chips. cooking temperature 17
0℃, time to reach the same temperature 90 minutes, 80 minutes at the same temperature
It was held for a minute to form a bulb.

Claims (1)

[Claims] 1. A method for producing pulp by cooking a lignocellulose material in an alkaline cooking liquor or a cooking liquor containing sulfites, wherein the cooking liquor has a general formula (I) or (II) ▲mathematical formula, chemical formula, There are tables, etc. ▼・・・・・・( I
)▲There are mathematical formulas, chemical formulas, tables, etc.▼・・・・・・(I
I) (In the above general formula (I) or (II), R and X represent an alkyl group, a hydroxyl group, an alkoxyl group, a halogen atom, an amino group, or a hydroxylamino group. Also, m and n represent the number of substituents. is an integer from 0 to 4), or a quinhydrone compound thereof.
2. A method for producing pulp, characterized in that the dihydroanthraquinone according to claim 1 is 1,4-dihydroanthraquinone. 3. A method for producing pulp, characterized in that the tetrahydroanthraquinone according to claim 1 is 1,4,5,8-tetrahydroanthraquinone.