RU1826936C - Fireproof veneer - Google Patents

Abstract

Usage: wood processing industry, production of wood laminated glued materials. Summary of the invention: fire-resistant plywood is made using 21-40 wt.% Diammonium phosphate relative to the weight of absolutely dry veneer. 1 tab

Description

The invention relates to the woodworking industry, in particular to the production of wood laminated glued materials.

The purpose of the invention is to obtain a low-combustible wood laminate with reduced smoke generating ability and toxicity of combustion products.

Statistical data on fires and numerous experimental studies indicate that the smokiness of the rooms and the toxicity of gases and aerosols generated by flame burning or decay of combustible materials have a dominant effect on deaths in fires. Accordingly, the most important indicators of combustible substances are smoke formation and toxicity of combustion products.

When wood materials are burned, a significant amount of unburned particles is formed, which are carried away by the flow of hot gases from the sample in the form of smoke. Particles of coal residue, which are easily separated from the carbonized surface by the same streams of hot gases, also contribute significantly to smoke formation. As a result, the smoke-generating ability of wood materials, in particular plywood, is very high, and in case of fire people can die due to loss of orientation in a smoky room,

The introduction of diammonium phosphate into plywood as antilirene, especially in an amount of not less than 21%, significantly changes the combustion pattern. If ordinary plywood during the pyrolysis produces a large amount of combustible gases and a small amount of coal residue and a liquid fraction, then with the introduction of the above amounts of diammonium phosphate, the equilibrium of the pyrolysis reactions is shifted due to the catalysis of the dehydration reactions of cellulose and lignin. As a result, the effective activation energy of the dehydration process decreases, the temperature of its onset decreases, the rate of formation and the amount of released water increase. The formation of combustible gases slows down significantly and the yield of non-combustible coal residue increases. Thereby, the intensity of the gas flows is reduced. On the other hand, carSL formed on the surface of fireproof plywood

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the bonded layer is dense and holistic unlike conventional plywood, i.e. particles of coal residue in a much smaller amount are separated from the surface by relatively weak streams of hot gases. All these phenomena lead to a sharp decrease in smoke formation during the thermal decomposition of fire-resistant plywood compared to conventional Plywood.

In flame retardant plywood, the toxicity of combustion products is reduced due to several factors. Firstly, the amount of toxic gases emitted during combustion is reduced, especially carbon monoxide, the role of which is considered to be dominant among the toxic combustion products. Secondly, the temperature of the combustion products decreases. And thirdly, smoke formation is sharply reduced. The reason for these phenomena lies in the catalytic effect of diammonium phosphate on the pyrolysis of wood. Thus, by introducing into the plywood 21% or more of diammonium phosphate, it is possible to obtain a material with low smoke generating ability and relatively low toxicity of combustion products,

Example. For the manufacture of fire-resistant plywood, veneered peeled birch veneer with a thickness of 1.5 mm, phenol-formaldehyde resin SFZh-3014 in a quantity of

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ve 120 r / m2 veneer and diammonium phosphate in an amount of 0-50 wt.% by weight of absolutely dry veneer. A resin impregnated with diammonium phosphate is applied, resin is collected, 7-layer bags are collected and placed in a press. In the press, packages are held at a temperature of 125 ° C and a pressure of 2.0 MPa for 7 minutes. Pressure relief is carried out for 5 minutes. Smoke generation coefficient and mass toxicity index are determined from the plywood samples obtained. The results are presented in the table.

Thus, the introduction of 21-40% diammonium phosphate into the veneer makes it possible to obtain fireproof plywood with low smoke generating ability and toxicity of high temperature decomposition products.

Claims (1)

The invention Fire-resistant plywood, including wood veneer, impregnated with diammonium phosphate and an adhesive layer of phenol-formaldehyde resin, characterized in that, in order to improve the fire retardant properties of the plywood by reducing the smoke-forming ability and toxicity of the combustion products, the content of diammonium phosphate in relation to the mass is absolutely absolute dry veneer is 21-40% by weight.