DE2524699A1 - Fire resistant resin bonded chipboard - from wood chips preimpregnated with magnesium salts and alkaline earth oxides - Google Patents

Abstract

Sheets of chipboard are prepd. from dried wood chips impregnated with a binder which are spread out to form a sheet and pressed at elevated temp., the chips before drying being preimpregnated with an aqueous soln. of a Mg salt and simultaneously mixed with an oxide obtd. by calcination of an alkaline earth carbonate. Unlike conventional chipboard, the product is non-inflammable. The Mg salt can be MgCl2 or MgSo4. The oxide can be obtd. by calcination of MgCO3 or of dolomite (a mixt. of MgCO3 and CaCO3). The binder can be urea-or phenolformaldehyde resin, usually contg. phosphate or borate to improve fire-resistance, thus enabling the proportion of wood to be increased, or an inorganic prod. pref. a polyphosphate.

Description

Method of manufacturing wood chipboard The invention relates to a process for the production of chipboard, in which the wood chips after a drying process wetted with a binding agent and then covered by sprinkling a mat, whereupon it is attached to the plate under pressure and temperature be pressed.

This known production method has the advantage that the production such chipboard can go on very quickly, so that the plate from the beginning until the end of the procedure is completed in about 30 minutes.

A disadvantage of such a chipboard, however, is that it is flammable due to its composition.

The invention is accordingly based on the object of veriahren initially mentioned type to create with which it is possible while maintaining the advantages inherent in the above-mentioned procedure To make chipboard produced by this process non-combustible.

This object is achieved according to the invention in that the wood chips Tor be subjected to a pretreatment of the treatment described above which they with an aqueous solution of magnesium salts with simultaneous addition are wetted by alkaline earth carbonates burnt to form oxides.

In this way it is achieved that in the subsequent in above As described, drying takes place a mineral coating of the wood fibers or wood chips occurs, which leads to the non-combustibility of the panels produced in this way.

There are processes for the production of non-combustible chipboard known, in which the wood fibers of a similar pretreatment as described above be subjected, however, after wetting, the wood fibers are subjected to a Qaell process subjected until a pulp is formed, which is then shaped into plates and over be dried for a longer period of time at temperatures of approx. 50 - 600 ° C. The production of such a plate therefore takes several days. Also serve in these known processes the magnesia bonds as a binder, which leads to Consequence has that in addition to their long production time the after known method produced plate significantly lower strength values than having the plate produced by the method according to the invention.

The Magnesiousalse in aqueous solution can be magnesium chlorides or also be magnesium sulfates. The use of magnesium chloride supplies in-their Fire behavior slightly better panels while using magnesium sulfate has the advantage that the treated wood chips at much higher temperatures can be dried, which further shortens the production time.

In the case of alkaline earth carbonates caustic burned to oxides, it can are either magnesium oxide or so-called dolomite, which is a mixture made up of magnesium carbonate and calcium carbonate. The use of dolomite can have the advantage that dolomite can be obtained more cheaply.

In the known manufacturing process for the production of combustible Chipboards are organic binders such as carbamide-formaldehyde resins or Phenol-feraldehyde resins, common.

It helps to strengthen the non-combustibility if the Binder when added with flame retardant Hinenlsalzen, such as phosphates and Borates can be sprayed and moistened with dasit, in particular in this way the Wood content can be increased.

Finally, it is possible to use mineral binders instead of organic binders inorganic binders, preferably based on phosphoric acid compounds, in particular polyphosphates to be used.

The non-combustible ones that can be produced with the method according to the invention Wood chipboard can have the compositions mentioned in the two examples below to have. The panels have different wood and mineral proportions, whereby the plate according to Example II with larger wood enteil lighter than that with the higher one ralische share according to example I. Both are non-flammable Plates.

Example 1 33.3 parts by weight of wood chips are combined with 26.7 parts by weight Magnesium chloride in aqueous solution with the simultaneous addition of 31.2 parts by weight Caustic burned magnesium oxide is wetted, whereupon the mixture is dried and is wetted with 8.8 parts by weight of a binder, whereupon the spreading into a mat and the pressing into a plate takes place.

Example II 38.9 parts by weight of wood chips are combined with 26.0 parts by weight Magnesia chloride in aqueous solution with the simultaneous addition of 26.0 parts by weight Caustic burnt magnesium oxide is wetted, whereupon the mixture is dried and mixed with 9.1 parts by weight of a binder is wetted, followed by spreading to form a Mat and pressing into a plate is done.

Claims (1)

Claims Process for the production of chipboard, in which the wood After drying, chips are wetted with a binding agent and then through Sprinkle to be spread out on a mat, whereupon it is pressurized and to the plate Temperature are pressed, characterized in that the wood chips before drying are subjected to a pretreatment in which they are soldered with water Magnesium salts with the simultaneous addition of alkaline earth carbonates caustic burnt to oxides are wetted. 2, method according to claim 1, characterized in that as magnesium salts Magnesium chloride can be used in aqueous solution. 3. The method according to claim 1, characterized in that the magnesium salts magnesium sulfate can be used in aqueous solution. 4. The method according to any one of claims 1 to 3, characterized in that that as caustic alkaline earth carbonates burnt to oxides, magnesium oxides are used will. 5. The method according to any one of claims 1 to 3, characterized in, that dolomite is used as the alkaline earth carbonate caustic burned to oxides. 6. The method according to any one of claims 1 to 5, characterized in that that organic binders, such as carbide-rmaldehyde resin. the phenol-formaldehyde resins, be used. 7. The method according to claim 6, characterized in that the binding agent When added, they are wetted with mineral salts that prevent the skin from developing, such as phosphates and roasts will. 8. The method according to any one of claims 1 to 5, characterized in that that mineral inorganic binders are used. 9. The method according to claim 8, characterized in that mineral inorganic binders based on phosphoric acid compounds, in particular Polyphosphates can be used. 10. The method according to any one of claims 1 to 9, characterized in that that 33.3 parts by weight of wood chips with 26.7 parts by weight of magnesium chloride in aqueous solution with the simultaneous addition of 31.2 parts by weight caustic burnt magnesium oxide are wetted, whereupon the mixture is dried and covered with 8.8 parts by weight of a binder is wetted, whereupon the spread to a Had and pressed into a plate. 11. The method according to any one of claims 1 to 9, characterized in that that 38.9 parts by weight of wood chips with 26.0 parts by weight of magnesium chloride in aqueous solution with the simultaneous addition of 26.0 parts by weight caustic burnt magnesium oxides are wetted, whereupon the mixture is dried and mixed with 9.1 parts by weight of a binder is wetted, whereupon the spreading to a Had and pressed into a plate.