DE1001117B - Dry extinguishers and process for their manufacture - Google Patents

Description

GERMAN

Fire extinguishing agents have been known for a long time which, in addition to water, also foam-producing substances such as Contain saponin or protein compounds. Such extinguishing agents become one at the source of the fire A layer of show that stifles the fire. Further fire extinguishing agents are known which, in addition to water, contain crust-forming substances such as water glass, graphite, Contains barite or silicone. When using such agents it has been shown that in In some cases the foam is soon destroyed or the crust flakes off, leaving only an insufficient one or temporary extinguishing effect is achieved. Dry extinguishing agents in powder form are also known, as an essential part of z. B. Natriutnbicarbonat, which under the action of Heat releases carbonic acid and thus prevents the air supply to the flame. Such fire extinguishing agents have the disadvantage that they do not adhere to the burning object and therefore do not offer long-term protection.

It is also known to dissolve or disperse synthetic resins in water and to use these solutions or Dispersions, optionally after the addition of phosphoric acid salts and / or borates and / or Inorganic crust-forming substances and / or carbohydrate and / or protein-containing substances as To use fire extinguishing agents; the disadvantage of these agents is that they are not stable, but rather tend to subsequent hardening of the dissolved resin and thus make the application more difficult.

It has now been found that these disadvantages are avoided and an excellent extinguishing effect is achieved if dry extinguishing agents are used which, in finely divided form, contain condensation products of urea with formaldehyde, phosphoric acid and / or boric acid, their compounds or their addition products with the condensation products. When they hit the source of the fire, such dry extinguishing agents form a well-adhering, very tough and difficult-to-destroy carbon-containing foam, which prevents the air from entering, thereby extinguishing the flame and suppressing any further burning of the material. At the same time, the excellent thermal insulation prevents the combustible material from flaring up again. Presumably the foam arises in such a way that the condensation product changes into a viscous state under the influence of heat and in this state is converted into foam by gases which are formed during the heat under the action of phosphoric acid or boric acid; At the same time, at least partial decomposition of the condensation product takes place, which on the one hand allows a higher carbon material to develop, on the other hand. "Dry extinguishing agents and processes
for their manufacture

Applicant:

German gold and silver refinery

formerly Roessler, Frankfurt / M.,

Weißfrauenstr. 9

Dr. Wilhelm Schulenburg, Frankfurt / M.,
has been named as the inventor

contributes to the formation of foam itself through the development of gas.

In place of formaldehyde, form ^ aldehyde-supplying substances such. B. Parafccmaldehyde or Hexamethylenetetramine can be used. Instead of urea, you can also use its derivatives, e.g. B. Use thiourea, dicyandiamide, melamine, guanidine.

Instead of phosphoric acid or boric acid, their compounds, e.g. B. their salts are used will. As have been particularly suitable, for. B. the ammonium salts of phosphoric acid have been proven, those in the heat with the elimination of ammonia and water vapor during foam formation help along. With good success you can z. B. also the addition products of phosphoric acid or boric acid need of urea-formaldehyde resins.

It has been shown that particularly good effects are achieved when the dry extinguishing agent on 1 part of the urea-formaldehyde condensation product 1 to 4 parts of phosphoric acid or boric acid or contains their compounds.

In some cases it is useful to check the carbon content of the foam that forms in the heat to increase by adding carbohydrates to the other ingredients, e.g. B. starch, sugar, or dextrin CellulO'Severbindungen, and / or protein-containing substances, z. B. glue can be added. The addition of these substances but should not be more than 0.7 parts to 1 part of phosphoric acid or boric acid or their compounds.

In addition to the substances mentioned, the dry extinguishing agents according to the invention can also contain other

609 766/269

contain known inorganic crust-forming substances in finely divided form, e. B. asbestos flour, kieselguhr, Plaster of paris, barite or the like.

For the production of the dry extinguishing agent according to the invention one proceeds appropriately so that urea or its derivatives with formaldehyde or Formaldehyde-producing substances are condensed. The condensation product is then hardened, crushed and mixed with the other ingredients. One can also proceed in such a way that-condensation of the formaldehyde or the formaldehyde-supplying substances with urea or its derivatives in the presence one or more of the remaining solid components of the dry extinguishing agent is carried out. This mixture is then hardened and crushed and can optionally also be mixed with other solid components be mixed up.

Examples

20th

1. A urea-formaldehyde resin, obtained by condensing 1 mol of urea with 2.5 mol of formaldehyde as paraformaldehyde in the presence of 0.5 mol of phosphoric acid, is finely ground so that there is a sieve of at least DIN 40 (1600 Meshes / cm ² ) and intimately mixed with monoammonophosphate of the same grain size in a ratio of 1: 2.5 with the addition of 7% dextrin powder.

2. 600 g of a condensation product of dicyandiamide and formaldehyde are finely ground with 1200 g of diammonophosphate, 50 g of boric acid and 140 g of soluble starch, passed through a sieve of 1400 mesh / cm ² and mixed with 70 g of finely ground gypsum.

3. 300 g of dimethylolurea, 50 g of urea orthophosphate, 350 g of monoammonophosphate, 75 g of asbestos flour and 150 g of dextrin are mixed well and finely ground so that the mixture passes through ^{a 1600 mesh / cm 2 sieve without residue.} When it is thrown at the source of the fire by the pressure of carbonic acid, it forms a flame-suffocating solid foam layer.

Claims (7)

Patent claims: 1. Dry extinguishing agent, characterized in that it condensation in finely divided solid form products of formaldehyde or substances that supply formaldehyde with urea or its derivatives and phosphoric acid and / or boric acid, their compounds or their addition products with the formaldehyde condensation product contain. 2. Dry extinguishing agent according to claim 1, characterized in that it is based on 1 part of the condensation product Contain 1 to 4 parts of phosphoric acid and / or boric acid or their compounds or addition products. 3. Dry extinguishing agent according to claim 1 or 2, characterized in that it contains carbohydrate and / or contain proteinaceous substances. 4. Dry extinguishing agent according to claim 3, characterized in that it is based on 1 part of phosphoric acid and / or boric acid or its compounds or addition products less than 0.7 parts of carbohydrate and / or contain protein-containing substances. 5. Dry extinguishing agent according to Claims 1 to 4, characterized in that it forms crusts contain inorganic substances in a finely divided state. 6. Process for the production of dry extinguishing agents according to Claims 1 to 5, characterized in that that formaldehyde or formaldehyde-producing substances with urea or its derivatives condensed, hardened, crushed and mixed with the other ingredients. 7. A method for the production of dry extinguishing agents according to claim 1 to 5, characterized in that that the condensation of formaldehyde or the formaldehyde-supplying substances with urea or its derivatives in the presence of one or more of the other solid constituents of the Dry chemical is carried out. Publications considered:,
French patent specification No. 910 468. © 609 766/269 1.57