CS240579B1 - Impregnating agent - Google Patents

Abstract

Impregnating agent based on phenol-formaldehyde condensates for impregnation of porous materials. The agent consists of a mixture of linear oligomers of condensation products of phenol, cresols and xylenols with formaldehyde, which are obtained during the purification of 2,6-xylenol by selective ortho-condensation with formaldehyde or paraformaldehyde, or their solutions in solvents.

Description

The invention relates to an impregnating agent for impregnating porous materials such as wood and paper against the effects of moisture, mold, fungi and bacteria.

It is known that phenolic substances are effective disinfectants and fungicides. However, free phenols are not very resistant to water, which is why condensates of phenol with formaldehyde are used for impregnation of wood and paper. It has now been found that phenol-formaldehyde condensates, which are waste products of the dry cleaning of 2,6-xylenol, are excellent impregnating agents.

The subject of the invention is an impregnating agent for impregnating porous materials based on phenol-formaldehyde condensates consisting of 20 to 100% by weight mixtures of linear oligomers of condensation products of phenol, cresols and xylenols with formaldehyde, which is obtained during the purification of 2,6-xylenol using formaldehyde or paraformaldehyde with a softening point of 50 to 80 °C and up to 80% by weight of alcohols, ketones, esters, aromatics, chlorinated hydrocarbons or mixtures thereof, based on the total weight of the impregnating agent.

The source of 2,6-xylenol is the reaction mixture after methylation of phenol, which contains mainly methylphenols (o-, m- and p-cresols). To a lesser extent, quantitatively insignificant, other products of phenol methylation are also present. Depending on the reaction conditions of phenol methylation, the reaction mixture contains a different ratio of o-cresol and 2,6-xylenol, depending on whether the main methylation product is o-cresol or 2,6-xylenol. After distilling off a significant part of the o-cresol, 2,6-xylenol remains in the rest of the reaction mixture as the main and most important component. Of the other methyl derivatives of phenol, o-, m- and p-cresols alone account for 90 to 95 % by weight of impurities.

From this mixture, 2,6-xylenol was isolated mainly by physical methods such as rectification, crystallization, or fractional crystallization, or a combination of these methods. Recently, suitable methods for refining crude xylenol by selective orthocondensation with paraformaldehyde or formaldehyde in the presence of catalysts have been found.

The condensation reaction product is essentially a mixture of linear oligomers (mainly dimers and trimers) of condensation products of phenol, cresols and xylenols with formaldehyde. The chemical structure is identical to cresol ortho-novolacs. The condensate is a neutral substance with a flash point higher than 140 °C, insoluble in water and paraffinic saturated hydrocarbons, easily melting usually between 50 and 80 ³ C and soluble in a number of organic solvents, mainly in alcohols such as methanol, ethanol, cyclohexanol, cyclic and aliphatic ketones such as ethyl methyl ketone, diethyl ketone, cyclohexanone, esters such as methyl formate, ethyl formate, ethyl acetate, methyl acetate, aromatic hydrocarbons such as benzene, toluene, chlorinated hydrocarbons such as chlorobenzene, chloroform, trichloroethylene and mixtures thereof. The properties of this waste product can be advantageously used in practical applications. Impregnation with waste condensate can be carried out in the form of a solution, preferably in alcohol, or a melt, for example by spraying, dipping in the melt, etc. The surfaces of materials treated with this condensate are smooth, shiny, mechanically and weather-resistant, and transparent. Transparency allows the use of coatings where it is important that the structure of the original material remains visible. Waste condensate solutions and melts can be colored as desired, using a variety of organic dyes and inorganic pigments.

The invention will be illustrated by the following example: % in the example are by weight.

Example 1

500 g of 2,6-xylenol was refined by the method described in the description of the invention to the Czechoslovak patent No. 231 085, example 1. The xylenol used for refining contained 202% of other methyl derivatives of phenol.

After the described refining process and distillation of pure xylenol, the residue in the reboiler was mixed with 150 g of ethanol and the resulting solution of the condensation residue was separated from a small amount of solid phase by filtration. 302 g of solution was obtained. The concentration of the waste product dissolved in ethanol was determined by evaporation and was 51.02 %/o. A wooden cube prism of 6 cm edge made of dried fir wood was impregnated with the prepared solution, which was alternately wetted with water (30 min) and, after wiping the water from the surface, freely dried in a stream of air. The maximum weight gain of the impregnated cube in 30 cycles was 2.6 %/o. The condensate coating on the walls of the cube remained unchanged.

The weight gain of the same unimpregnated test specimens ranges between 18 and 25%. After several cycles, the specimens crack.

Example 2

By the method described in Example 4, see Czechoslovak Patent No. 230,842, 1,000 g of crude 2,6-xylenol was refined. The xylenol used for refining contained 20.2% of other methyl derivatives of phenol.

After completion of the refining and distillation of xylenol, the residue in the reboiler was mixed with 700 grams of a mixture of toluene and methanol (1:1) and the resulting solution was filtered.

999 g of solution was obtained, which, according to the determination by evaporation, contained 308 g of dry matter.

Tests of the effectiveness of solution impregnation were carried out in the same way as in Example 1.

The maximum weight gain of the impregnated cube in 30 cycles was 2.6%. The condensate coating on the cube walls remained unchanged.

Example 3

Xylenol containing 6.4% of other alkylated methyl derivatives of phenol was refined by the method described in the invention applications. Part of the residue after refining was always dissolved in an organic solvent or a mixture of organic solvents and the solutions were used to impregnate wooden test specimens, as described in Example 1. The remaining parts of the condensate were also used for impregnation, but the impregnation was carried out from the melt.

A summary of the experiments and results is given in the table.

Example 3.1 3.2 3.3 3.4 3.5 3.6 Refining according to AO no. 232,834 235,679 232,870 235,607 235,608 236 128 Example 3 13 4 1 5 7 Melting point residue in °C 73 65 80 69 71 72 Weight distillation remainder in g 96 96 92.4 96.2 93.8 93.1 Solution condensate to impregnate Weight condensate in g 16 24 24 24 10 5 Weight solvents in 160 24 90 90 100 100 Type ethanol, methanol, solvents acetone toluene ' ethanol (1:1) acetone (64: 36) ethanol chloroform Increment masses prism Impregnation from solution in % 2.2 2.6 2.5 2.5 1.9 3.5 From the melt in % 1.8 1.8 1.8 1.8 1.8 1.8 Appearance impregnated areas smooth, shiny, without cracks ¹ Note: Weight gain of the prism was established-

out after 30 cycles.

For weight gains of non-impregnated bodies, see example 1.

The starting amount of crude xylenol for all tests was 1000 g. The other substances were changed in the ratio of the components used in the cited example of the aforementioned author's certificate.

Claims (1)

SUBJECT An impregnating agent based on phenol-formaldehyde condensates for impregnating porous materials, characterized in that it consists of 20 to 100% by weight of a mixture of linear oligomers of the condensation products of phenol, cresols and xylenols and formaldehyde which is lost during purification of 2,6-xylenol 50 to 80 ° C and up to 80% by weight of alcohols, ketones, esters, aromatics, chlorinated hydrocarbons or mixtures thereof, based on the total weight of the impregnating agent.