DD219514A1 - TWO-STAGE PROCESS FOR PRODUCING WOODEN SLIP - Google Patents

Abstract

The invention relates to a two-stage process for the production of groundwood pulp. Its task is to propose a method that allows a gentle and effective extraction of the fiber out of the wood structure and is applicable in conventional systems. According to the invention, the object is achieved by subjecting the wood in a first stage to a pressure treatment of from 0.1 to 1.5 MPa and then defibering the wood under atmospheric conditions.

Description

-,. ·. ^v /. .

Two-stage process for the production of groundwood

Field of application of the invention :

The invention relates to a two - stage process for producing wood pulp in a wood grinder according to the press or continuous principle and is used in the paper industry.

Characteristics of the known tecTrni see solutions

- The production of stone-groundwood of higher quality can be achieved by improving the plastification conditions of lignin. The basis for this is the strong temperature and luminous dependence of the plastification of the lignin. , ''.

In the long-known brown sanding process by hydrothermal treatment of wood at temperatures around 160 ⁰ C, a state of lignin is reached, which allows for a longer period of time, the detachment of long supple fibers .. The disadvantage of the method is'. intense browning of the wood. Pur-the whiteness ^: Schlifferzeugung is therefore the strongly developed in recent years loops under pressure of greater importance (DE 2877039). The process prevents evaporation phenomena in the immediate IPaserherauslösung by a pressure atmosphere in the grinding chamber and the associated boiling point increase of the process and Kapillarwassers of the wood .. This makes it possible, the resulting temperatures in the wood for a more favorable plasticizing the middle

lamette and thus to gain longer, smoother fibers. The improvement of the wood pulp quality, however, is .with a great technical equipment. Effort connected. > Here. comes that the method is tied to the press grinder principle and that the service life of the grinder stones are greatly reduced due to the high load. It has also been proposed to improve the conditions of Faserherauslösung by special stone structures or the use of chemicals for boiling point of the water (DB 290194-3, DE 2853716, DS 3010394). The realization of these steps, however, encounters considerable difficulties. : · ;. , . ' , ·. '''.' ·.: -

Furthermore, it is known to pre-warm the wood before the grinding process (WP D 21 B / 261 A24). Different types of energy storage * are used. The method attaches particular importance to favorable heat transfer, as it has condensing water vapor. However, this means that the plastification area of lignin can not be reached. - - '

Aim of the invention;

The invention has set itself the goal to achieve an improvement in the pulp quality and thus an increase in use of groundwood. ·

Essence of the invention . ₍ ' ^v .

The invention has for its object to propose a method that allows a gentle and effective extraction of the fiber from the timber structure and is applicable in conventional systems.

According to the invention the object is achieved in that. the wood in a first stage of a pressure treatment of 0.1 to 1.5 MPa at temperatures between 100 and 160 ⁰ C and in a saturated atmosphere (here are also 100% Wssser conceivable) subjected and thus a plasticization of lignin is achieved.

The temperature increase in the. Hoiah can be achieved both by thermal energy in the form of water vapor or heated Wasser'als .'- .. Also by electrical energy in the form of high-frequency energy. The treatment time should be minimized as required, but should not exceed 3 hours ... ''. ; · .. '.' .. · ... '..'''. -. 'Ih the "2 * stage, the wood is then pulped in a wood grinder according to the continuous action or press principle means of a special grinding wheel at atmospheric pressure and spray water temperatures between 5O ⁰ O ⁰ C and 80.

Example of execution ^see ' .

The invention will be explained in more detail below with reference to an exemplary embodiment, wherein the following method steps are necessary:.

1. Loading the treatment room with pulpwood;

2. applying the pressure atmosphere; , ;

3 · Energy input into the wood in the form of heat energy (energy source water or water vapor) or electrical energy (high-frequency energy) until reaching the plastication area between 1OG - 160 ⁰ C;

4. Return of the energy carrier media as required; 5 · removal of wood from the treatment room; , 6. Grinding of the wood under atmospheric conditions} at spray water temperatures between 50 ⁰ G and 80 ⁰ C on a grinder stone or a suitable abrasive body, eg. _: B .. steel wheel. :

Further process variables are determined by the purpose of the HoIz cut. , ^R. :

Claims (4)

Inventions claim h . , ,. '' 1. Two-stage process for the production of groundwood in a wood sander after the press / or. Continuously principle characterized, in that the timber before being fed to the grinding zone at temperatures between .100: C and 'be in a saturated atmosphere of a pressure "and IGO ^0: treatment of 0.1 to 1.5 MPa is exposed and that thereafter a defibration of the wood is carried out under atmospheric conditions at spray water temperatures between 50 and 80 ⁰ C. 2. Two-stage process according to point 1.dadurch in that the energy supply during the pressure treatment by heat energy in Iform of water vapor or heated water "or by electrical energy in the form of high-frequency energy 3. Two-stage procedure, after items 1 and 2 _; characterized in that the wood pulp produced is optimized by Nachmahlung or fractionation in its quality. 4. Two-stage process according to item 1 to 3, characterized in that inferior wood qualities are used .. '.