CS276208B6 - The way of protecting wood from fire by impregnation by dipping - Google Patents

Abstract

The purpose of the solution is to protect wood from fire by impregnation by dipping. The stated purpose is achieved by impregnating the wood in 25 to 85 wt. % solution of trihydrogenphosphoric acid at a temperature of 10 to 30 °C for 1 to 20 h and subsequent immersion in the same solution after addition is impregnated with sodium thiosulfate at a temperature of 10 to 30 °C for 5 min. up to 4 h and dried. The solution is used in construction, furniture and the mining industry.

Description

The invention relates to a method of protecting wood from fire by dipping. Wood or other lignocellulosic materials are used as a structural, decorative or insulating material in the construction, mining and furniture industries. Their non-slippery property is low fire resistance. So far, the most common method of protecting wood from fire is to impregnate wood with a combined process (JP 63137802, JP 61141786, DE 3537251). Impregnation is carried out by briefly soaking in 5 to 30 wt. % solutions or by coating. The disadvantage of the above-mentioned processes is that the impregnating agent of the materials can be gradually washed out with water, thereby reducing fire protection, aesthetic appearance and mechanical properties of the wood.

The above-mentioned drawbacks are substantially eliminated by the method of protecting wood from fire by impregnating the wood with impregnation of the wood by dipping in 25 to 85 wt. % of a solution of trihydrogenphosphoric acid at 10 to 30 ° C for 1 to 20 h, followed by impregnation by dipping in the same solution after addition of sodium thiosulfate at 10 to 30 ° C for 5 min. up to 4 h and dried. The advantage of the method of protecting wood from fire by impregnation by dipping compared to previously used solutions is that the sulfur is released from the salt by the concentrated acid solutions and forms a protective layer on the wood surface that heats it from the fire. The protective layer cannot be washed with water.

These examples illustrate, but do not limit the invention. Example 1

Ash plates (7 pcs.) 220 mm wide, 195 mm wide, and 10 mm thick are impregnated with 2 liters of 85 wt. % of trihydrogenphosphoric acid at 10 ° C for 1 h. Add crystalline sodium thiosulfate pentahydrate (500 g per 7 plates) and impregnate for 5 min. at 30 ° C. The plates are rinsed with water and dried to constant weight. A material is obtained whose flammability grade according to ČSN 73 0862 is C 1, hardly flammable (Q = 252.4), while the flood material has a flammability rating of C 2, a medium flammable mass (Q = 309.5). Example 2

The procedure is as in Example 1 except that the material is impregnated with 25 h in 25 wt. % of trihydrogenphosphoric acid at 30 ° C and 4 hours after addition of 100 g of crystalline sodium thiosulphate pentahydrate at 10 ° C. A material is obtained whose degree of flammability according to ČSN 73 0862 is C 1, hardly flammable (Q = 172.3).

The invention is of use in the construction, furniture and mining industries.

Claims (1)

PATENT REQUIREMENTS The method of protecting wood from fire by impregnation by dipping, characterized in that the wood is impregnated for a short time by dipping in 25 to 85 wt. % of a solution of trihydrogenphosphoric acid at 10 to 30 ° C for 1 to 20 h and subsequently impregnated by dipping in the same solution after addition of sodium thiosulfate to the impregnating acid solution at 10 to 30 ° C for 5 min. up to 4 h and dried.