DE1066411B - Process for the production of semi-pulp from wood - Google Patents

Description

When it comes to wood processing, a fundamental distinction must be made between chemical and construction timber. At Construction wood has different requirements than chemical wood. If possible, the timber should not have any water contain more and be completely dry, this is not the case with chemical wood, which is to be processed into fibers demands. The greatest possible freedom from water in the construction timber is achieved through longer storage under special Conditions or artificial drying achieved. In addition, this is especially important for the lumber Interesting heartwood, which develops after the tree has been active for 30 to 40 years and as core, dead wood has a significantly lower water content than that on the outside sapwood located on the tree. The wood is the core through condensation reactions and the like solidified.

Chemical wood is stored in addition to the purpose of storage in order to ensure that it is not even to achieve high moisture content. A drying as is the case with construction timber, chemical wood is not necessary for pulp production. Lumber is generally dried to above the fiber saturation point, so have z. B. Hohelsnäne_ an average water content of fl ^^^ Br ^ sagespäne 31% ,. Peeling shavings from pulp production 34%, peeling shavings from wood pulp 48%, peeling shavings from ladder production 35%. The wood shavings as waste wood from pure construction timber are therefore in terms of moisture content well below the fiber saturation point of about 28%. Due to the long storage and drying In the construction timber, keratinization and hardening of the wood material occurs, which is particularly unfavorable noticeable in the wood chips. This chip material can only be recovered with difficulty due to swelling • ■ to make them operational. A quick impregnation of the wood with the digestion solution is made possible by the Prevents cornification.

It is known that half-pulp by the so-called neutral sulfite process using a weakly alkaline Prepare buffered sodium sulfite solution. It is also known to be semi-pulp after the semi-chemical Sulphate process or after chemical digestion to produce with caustic soda from wood. The use of hardwood is preferred.

Another known process is used to produce chemical wood, such as peeling chips, hems and sauerkraut used by grinding shops, and from it after an alkaline pretreatment and a subsequent Cooking with alkali or alkaline earth salts produces a semi-pulp-like product.

It is also known to produce a semi-pulp-like material from hardwoods by treatment with caustic soda solution in the vicinity of 100 ° C.

Method of extraction
of semi-pulp made of wood

Applicant:

Holzverzuckerungs-Gesellschaft mb H.,
Holzminden, Rumortalstr. 29

Dr.-Ing. Wilhelm Hüttinger, Holzminden,
has been named as the inventor

It is also known to use plant material, e.g. wood shavings, by mechanical treatment in to transfer a pre-shredded material and then with an aqueous solution of 0.5 to 0.7% To further mechanically crush caustic soda or alkaline earth Ixm temperatures of 60 ° C. This creates a Mass from which fiberboard or other shaped bodies can be produced. Through the treatment with alkali the mechanical digestion to wood fibers is supposed to be facilitated. It is about not about a semi-chemical digestion, but about mechanical defibration, from wood shavings To produce fiberboard, molded articles and the like.

Finally, it is known, wood chips, wood chemistry thus, be treated with an alkaline solution of l> ei 90 to 10O ⁰ C and then to carry out an acid sulfite pulping.

Finally, it is not new to subject peeling chips and wood shavings to mechanical pre-shredding and then to treat the pre-shredded material in a pulper at atmospheric pressure with the addition of alkali at 90 to 95 ° C. Then 10 to 15% caustic soda are used. After this treatment, a material is obtained in a further fiberizer which, at a freeness of 15 to 18 ⁰ SR, has a breaking length between 1600 and 2000 m.

In the method on which the invention is based are made from wood shavings during pre-extraction and subsequent boiling with neutral sulphite at the same degree of freeness, papers are obtained which have a tearing length of 50,000 to 6,000 m and are made from peeling chips have a height of 6000 to 7000 m.

The substance produced in this way is, as these values show, Far superior in strength to that produced by the method described above.

909 630/100

The method of the invention provides a pre-treatment of the aforementioned wood with an alkali or Erdalkalilösung with an initial p _H value of about 7, for example 9, and such a concentration in the heat before that after about 2 hours of exposure to a maximum of 110 ⁰ C. p _H value is below 7, for example, like 5 to 6 This pretreatment removes a large part of the resins distributed on the surface, the wood is swollen and gently attacked to such an extent that the sulphite liquor later used for cooking penetrates and some of the dark-staining wood extracts are removed without the alkaline treatment of the wood known browning occurs.

During the neutral boil-off following the pretreatment, a Get semi-pulp that can be used for light-colored cardboard and light-colored packaging paper.

example 1

6 kg of wood shavings with a dry matter (TS) content of 85.6% = 5.13 kg TS are with a first cooking liquor, consisting of 30 l of water and 15 g of NaOH, added, heated to 100 ° C and about Maintained at 100 ° C. for IVa hours. You then leave them Drain the cooking liquid and continue to treat it in the same digester with an alkali-buffered sodium monosulfite solution.

The spent liquor from the pretreatment has a _pH value of 6.1, that is in the weakly acidic region.

The reaction mass is heated to 18O ⁰ C and held for about a few hours under pumping at this temperature.

The lye is then allowed to run off and 3.63 kg of substance (atro) are then obtained, i.e. a yield of 70%. After grinding to 48 ° SR, the fabric produced gives a tear length of 6760 m and a bursting pressure of 2.6 at 80 g / m ^{2 of} paper.

Example 2

6.7 kg wood shavings with 89.3% TS = 6 kg of wood dry matter are mixed with a first cooking liquor, 301 g water with 12.5 CaO, p _H value 11.4. The chips mixture is heated, kept at 100 ⁰ C IV2 hours and then peeled off. The liquor has a _pH value of 6.2. Subsequently, the cooking material is treated with a buffered with alkali Natriummonosulfitlösung, _pH value, heating 7.4 to 18O ⁰ C, held for 3 hours at this temperature and then peeled off the spent liquor and the residue washed briefly. 4 kg of substance (dry weight) are obtained, i.e. a yield of 66.7%. After grinding to 31 ° SR, this paper has a tear length of 7500 m and a bursting pressure of 2.41 at 80 g / m ² paper.

Claims (1)

Claim: Process for the production of semi-pulp from wood which has dried above the fiber saturation point, e.g. B. from chips, characterized gekeWTzeTchnet that the wood an alkali or Erdalkalilösung with an initial _pH value of 7 and such a concentration is pretreated to me that after about 2 hours of exposure at about 80 to 100 ⁰ C, the p _H -value drops below 7, whereupon the neutral sulphite process is carried out. Considered publications:
German patents No. 831 188, 904 376,
906 650; U.S. Patent No. 1,773,419; Das Papier, 5th year, 1951, pp. 329 to 338.