DE1209274B - Fire-retardant molded wooden body - Google Patents

Description

Fire-retardant molded wood-based bodies The difficulty in application known fire retardants for wood-based molding is that this Means, e.g. B. in wood chipboard, such as panels, the mechanical properties very adversely affect. Probably the adverse effects are, first of all partly due to the fact that the process of curing the synthetic resin binder is disturbed. As a result, the bonding of the wood-based material particles to one another is disadvantageous affects and as a result the necessary mechanical strengths of the finished Wood-based molded body no longer achieved. The reduction in strength also depends on the amount of fire retardant added. It has become general has shown that more fire retardants are required for adequate protection are considered to be allowed to maintain the necessary strength at all can.

Another difficulty is the incorporation of the fire protection agents into the molded wood-based body.

The wood material particles are glued with synthetic resin, mostly on urea, seldom bound on a melamine or phenolic resin basis. These are predominantly called processed aqueous solutions.

The fire protection agents are liquid or solid (in Powder form). In both cases, the protective agents can directly affect the wood-based material forming wood particles such as chips or fibers or the liquid synthetic resin glue can be added.

The direct addition to the chips requires the continuous ones that are customary today Manufacturing process very cumbersome dispensing devices. When adding liquid Protecting the chips, there is a risk of too much moisture in the wood chip materials is introduced, which has a harmful effect when hot-pressing the molded body. With powdery Protective agents, there is a risk of segregation.

The dry powder trickles down and the even powder Distribution in the molded wood-based body is not guaranteed.

More favorable is the addition of fire retardants to the liquid glue. With liquid fire retardants, however, there is a risk of the glue becoming too thick is diluted, thereby losing its cohesiveness and also too much moisture in the Chip-glue mixture is introduced. Powdered agents only dissolve to a limited extent and accordingly thicken the liquid glue in a very disadvantageous way, which nevertheless should be applied to the wood chips in as finely a distribution as possible. Puts one, ttm the means completely, to bring into solution and to reduce the If you add water or other solvents to increased viscosity, there is again a risk the occurrence of excessive moisture in the chip-glue mixture.

It has now been shown that it is surprisingly easier and more effective Way succeeds in solving these problems satisfactorily and thus wood-sulfur molded bodies with excellent properties. if the molded body is a fire retardant contains, which boric acid and antimony trioxide in the weight ratio of boric acid: antimony trioxide contains at least 1: 1.

It is of course possible that there are more known fire-retardant agents additionally contain or per se known measures are made to hinder the ignition or the penetration of fire.

The molded wood-based bodies according to the invention are advantageous here Impregnated throughout with the fire retardant, even if it is also for special wood it is possible that z. B. contain only further outlying layers of fire retardant or at least some enrichment in fire retardants compared to lower have lying shields.

In fact, it has been shown that the moldings according to the invention, especially chipboard, excellent fire-retardant properties with no reduction in potential of mechanical properties. Boric acid is naturally acidic, but is very sparingly soluble in water at room temperature.

Antimony trioxide reacts roughly neutrally and is also only very bad soluble. Each of the two substances has a certain fire protection effect. A mixture However, of the two results in a much increased effect when using boric acid with more than half the amount is included.

Particularly favorable effects are achieved when the weight ratio from boric acid to antimony trioxide about 2: 1 to about 10: 1, preferably about 7: 1.

The property of particularly poor solubility at room temperature Boric acid and also antimony trioxide are another advantage in the frame the invention. These compounds are also insoluble when mixed with liquid glue.

Both substances float evenly as the finest particles distributed in the liquid glue. With a correspondingly fine pulverization, the sprayability becomes of the glue-fire protection mixture not disturbed. The viscosity is increased, however, but not to the extent that it is complete with the fire protection agent hitherto striven for Solution would be the case. So it is quite possible the lower viscosity increase by adding a little water to reduce it again to such an extent that it is sprayed of the glue mixture is quite possible.

In this way, about 100 percent by weight and more of one Mixture of boric acid and antimony trioxide, based on the solid resin content of the liquid Glues, add, if necessary with a little water, without affecting the pH value or the The viscosity or other properties of the glue are changed in an impermissible manner. the The addition of water that may be recommended also depends on the value set by the supplier Solid resin content of the liquid glue. Glues with a solid resin content are common from about 50 to 75%. However, less than 1000 / o is sufficient to achieve such a protective effect to achieve that the wood-based molded body hardly ignites and on itself in any case goes out immediately as soon as the igniting flame is removed.

It is of course also possible to separate the fire protection means to add glue to the chips in solid or suspended form, albeit such Measure will probably only be preferred in special cases. According to the invention the certain flame retardants containing wood-based molded bodies charred without to promote an open fire. This forms a layer of carbon that itself does not burn and due to its poor thermal conductivity an extremely good one Gives thermal protection.

Claims (1)

Claim: Fire-retardant molded wood-based body with a Flame retardant content, characterized in that a flame retardant it contains boric acid and antimony trioxide in a weight ratio of 1: 1 to about 10: 1, preferably about 7: 1. Documents considered: German Patent No. 232 380; British Patent No. 731 130; Kollmann, technology of wood and the Holzwerkstoffe, Volume 2 (1955), p. 118.