DE1202120B - Process for preventing sticking in the manufacture of hard fiberboard - Google Patents

Description

Method of preventing sticking in the manufacture of hard fiberboard The present invention relates to manufacturing of all kinds of hard wood fiber boards (pressed boards).

As is known, wood fiber boards, etc., are manufactured by mechanically crushing wood and slurrying it in water, whereupon the slurry is formed into a sheet in a machine similar to a paper machine. The layer is drained until it is self-supporting and dried. In the case of hard or semi-hard wood fiber boards (press boards) and cardboard boxes, etc., pressing for 5 to 30 minutes at high temperature and high pressures (150 to 250 ° C and 25 to 100 kg / cm2) is carried out in order to consolidate the fiber material. During the pressing, the side of the layer which is opposite the wire side is in contact with the glossy plate, which is intended to give the fiberboard a smooth surface. During compression often occurs a disadvantage that the fibers adhere to the surface of the gloss plate, the appearance of the wood fiber board, etc., and deteriorates ührt f in an inferior product. In addition, this means that the glossy plate has to be changed frequently (often every 2 to 3 days) for cleaning. Such an exchange of the glossy plates naturally causes a decrease in production, which can amount to 100 / ", and of course incurs additional labor costs.

Usually the fiber layer is pre-pressed with connections treated, which give the wood fiber board, etc. a desired surface finish. Such substances are e.g. B. water-soluble cellulose, starch and alginic acid derivatives, that of fibreboard, etc. have an excellent surface finish and others impart desirable properties. Unfortunately, these named derivatives have that However, the problem of the fiber material sticking to the glossy plate is made even more difficult.

The method according to the invention for preventing sticking in the production of hard wood fiber boards, wherein a fiber layer is pressed at a temperature of 150 to 250 ° C and a pressure of 25 to 100 kg / cm2 with one side in contact with a glossy board and with the An oil and a water-soluble cellulose derivative are applied to the surface of the wet fiber layer before pressing, is characterized in that triethanolamine is added to the surface of the wet fiber layer before the heat pressing in such an amount that it is in contact with the glossy plate Surface layer is kept at a pH of 7 to 10 for 5 seconds to 5 minutes at the beginning of the pressing.

The triethanolamine is expediently the surface of the wet fiber layer added immediately before heat compression, advantageously in water or other solvents is dissolved or emulsified. Appropriately, a Surface-active compound added to prevent the penetration of this compound into the To facilitate fiber mass. The additional compound can also be used for surface treatment the layer used aqueous solution of the water-soluble cellulose, starch or alginic acid derivatives be dissolved or emulsified.

There is also a method of applying a casein coating Known paper. To prevent sticking to the hot gloss rollers, added certain amines, which affect the solubility of casein and a Reaction of the same with the added formaldehyde to catalyze.

The present invention, however, relates to a pressing of a still wet fiberboard, where the pressures and temperatures are much higher than in the known production of coated paper. Through the The special use of triethanolamine is intended to detach the finished fiberboard be made possible by the hot press plate; the claimed regulation of the pH value is in contrast to the above-mentioned known method only at the beginning of the pressing process necessary; also with the claimed method is no layer in the sense of a Coating formed.

Cellulose, starch or alginic acid derivatives that can be used are, for. B. water-soluble cellulose ethers and esters, such as cellulose sulfate, methyl cellulose, ethyl cellulose, methyl ethyl cellulose, oxyethyl cellulose, ethyloxyethyl cellulose, carboxymethyl cellulose, sulfomethyl cellulose, sulfoethyl cellulose, swollen starch, methyl starch, ethyl starch, alginic acid and their water-soluble salts. These compounds are normally used in amounts of 0.05 to 2, preferably 0.1 to 1 percent by weight, based on the fiber mass.

In addition to the above-mentioned adhesion of the lower wood fiber board, etc. on the plate gloss still the advantage is achieved according to the invention 'that the surface of the wood fiber board, etc. having better uniformity and dyeability. The physical properties of the finished press plate, etc., such as mechanical strength, water absorption and swellability in water, are not or only slightly impaired.

The invention is illustrated in more detail by the following examples. EXAMPLE 1 In the manufacture of a conventional hard wood fiber board, before the heat compression, an emulsion of the following mixture was sprayed onto the surface of the wet fiber layer: 55 parts of ethyloxyethyl cellulose, 70 parts of triethanolamine, 410 parts of tall oil esterified with glycerine, 45 parts of brown aniline paint, water to 30,000 Parts. The emulsion was used in an amount of 500 g / m 2 of the surface of the wood fiber board. It was found that this treatment completely eliminated sticking to the glossy plate during heat pressing. Example 2 Example 1 was repeated using the following mixture: 55 parts of carboxymethyl cellulose, 70 parts of triethanolamine, 410 parts of tall oil esterified with glycerine, water to 30,000 parts.

The results were the same as in Example 1. Example 3 Example 1 was repeated using the following mixture: 50 parts of ethyloxyethyl cellulose, 65 parts of triethanolamine, 400 parts of linseed oil, 20 parts of nonylphenolethylene oxide condensate (Berol VMA 09), 60 parts of brown aniline paint (Vesuvin), water to 30,000 parts.

The results were the same as in Example 1.

Claims (2)

Claims: 1. A method for preventing sticking in the production of hard wood fiber boards, wherein a fiber layer is pressed at a temperature of 150 to 250 ° C and a pressure of 25 to 100 kg / CM2 with one side in contact with a glossy plate and with the surface of the wet fiber layer before pressing an oil and a water-soluble cellulose derivative is applied gekennzeichn characterized et that the surface of the wet fiber layer in front of Wärmeverpressung also triethanolamine, in such an amount is added that in this way the standing with the gloss plate contacting surface layer at the beginning of pressing five seconds is held at a pH of 7 to 10 for up to 5 minutes. 2. The method according to claim 1, characterized in that a surface-active compound is added to the fiber material with the triethanolamine. Considered publications: German Patent Specifications No. 1010 370, 473 900.