SU93153A1 - The method of impregnation of raw plywood veneer in the production of wood plastics - Google Patents

Description

Usually, raw wood veneer with a moisture content of 70-100% prior to impregnation with artificial resins in the production of wood plastics is dried to a moisture content of 4-6%, which consumes a significant amount of steam.

The described "method of impregnation of plywood veneer" is that, in order to avoid drying, the impregnation of the resin is applied to the raw CO 2 NI solution of water-soluble and synthetic soluble resins by diffusion.

The method of impregnating the raw plywood veneer is dried in the following way.

The veneer obtained from the shelling machine and containing 70-100% of water is subjected for 10-20 minutes. squeezing water on the press with a stepped pressure increase up to 160 kg / cm. The water content in the spar after pressing does not exceed 40%.

By squeezing water through a spar, it is not only possible to reduce the moisture content in it and equalize the amount of the latter in individual sheets, but also to ensure a constant moisture content in the veneer, which favorably affects the subsequent impregnation with artificial resins.

The veneer, which contains 40% of water after pressing, is impregnated with a solution of artificial resins and absorbs it in an amount determined by the difference in the water content of the original veneer and in the veneer after pressing. after which the impregnation process will occur by diffusion. When the impregnating solution is absorbed by the veneer in an amount equal to or greater than the amount of water pressed, the diffusion impregnation can be carried out outside the impregnation bath, for example, in the feet.

When calculating the concentration of the impregnating solution, the water contained in the veneer after pressing is taken into account.

In connection with the partial adsorption of the resin by the wood fibers, the resin concentration in the solution may decrease as the veneer is soaked, but it must not be lower than the limit value at which the separation of the solution occurs. For each type of resin, this value is not the same: for water-soluble resins, it should not be; x 20%, and for alcohol-soluble resins - 30%.

To maintain the desired concentration of the solution within these values, an artificial resin is added in the required amount after each impregnation.

In certain conditions (veneer thickness, type of resin, etc.) impregnation and uncompressed veneer is possible. HanpJiMCp, can be impregnated with thin shion with relative humidity up to 100% in a solution of a water-soluble phenol-formaldehyde resin, having “eukrulini molecules, with a mode that is somewhat longer compared with that of the pressed veneer.

During the impregnation of raw veneer in a diffusion manner, the resin penetrates into the vessels and intercellular spaces of deep wood layers and is evenly distributed there, which is confirmed by the increased water resistance of wood plastics compared to plastics obtained by impregnating dry veneer.

The subject of the invention. A method for impregnating raw plywood veneer in the production of wood plastics, carried out by mechanically removing excess water from the veneer and introducing into it, after water-soluble or alcohol-soluble, artificial: resins by diffusion.