Pyrotechnical, aerosol-forming composition for extinguishing fires and process for its preparation

Abstract

The invention relates to fire-extinguishing technology, in particular to pyrotechnical compositions for extinguishing fires and processes for their preparation. The invention allows to prepare pyrotechnical, aerosol-forming compositions with predetermined physico-mechanical properties, increased combustion velocity, reduced combustion temperature and large weight portion of solid particles with 1-2 μm in the aerosol. The pyrotechnical, aerosol-forming composition for extinguishing fires contains: as gas-aerosol-forming agent 2 fractions of dicyandiamide with 40-80 μm and 7-15 μm at a weight ratio of 80:20, as combustible binder 2 fractions of a polycondensate of formaldehyde with an organic compound, which is preferable selected from the group consisting of melamine, carbamide and phenol, with 70-120 μm and 10-25 μm at a weight ratio of 70:30, as oxidizing agent 2 fractions of an alkali nitrate with 15-25 μm and 1-7 μm with the following content of the components in % by weight: Gas-aerosol-forming agent 9-20 Combustible binder 6-14 Oxidizing agent the balance. The process for preparing the composition comprises the steps of pre-application of potassium chromate, potassium dichromate or ammonium dichromate, graphite on the surface of the oxidizing agent and the mixing of the components in a predetermined succession. The invention may be used in fire-extinguishing technology.

1 . Pyrotechnical, aerosol-forming composition for extinguishing fires, containing dicyandiamide as gas-aerosol-forming agent, a polycondensate of formaldehyde and an organic compound as combustible binder and an alkali nitrate as oxidizing agent, characterized in that the gas-aerosol-forming agent, the combustible binder and the oxidizing agent consist of two fractions: 40-80 μm and 7-15 μm at a weight ratio of 80:20, 70-120 μm and 10-25 μm at a weight ratio of 70:30, 15-25 μm and 1-7 μm at a weight ratio of 25:75, respectively, with the following content of the components in % by weight:  
                                           gas-aerosol-forming agent   9-20         combustible binder   6-14         oxidizing agent   the balance.                                           
 
     
     
         2 . Composition according to    claim 1   , characterized in that it contains a polycondensate of formaldehyde and melamine or carbamide as combustible binder.  
     
     
         3 . Composition according to    claim 1   , characterized in that it contains a phenolformaldehyde resin as combustible binder.  
     
     
         4 . Process for the preparation of the pyrotechnical, gas-aerosol-forming compositions for extinguishing fires according to any of    claims 1    to    3   , comprising the steps of mixing the combustible binder, the oxidizing agent and the gas-aerosol-forming agent in powder-form and molding of the mixture, characterized in that at first the fraction of the combustible binder with 70-120 μm is mixed with the fraction of the oxidizing agent with 10-25 μm and the fraction of the gas-aerosol-forming agent with 40-80 μm, and subsequently their fractions with 10-25 μm, 1-7 μm and 7-15 μm are added to the obtained mixture.  
     
     
         5 . Process for the preparation of the pyrotechnical, aerosol-forming compositions for extinguishing fires according to any of    claims 1    to    3   , comprising the steps of mixing a solution of the combustible binder, the oxidizing agent and the gas-aerosol-forming agent, and subsequently drying, granulating with drying and molding, characterized in that the mixing is carried out by dispersing the fraction of the oxidizing agent with 15-25 μm and the fraction of the gas-aerosol-forming agent with 40-80 μm in a solution of the combustible binder, and subsequently their fractions with 1-7 μm and 7-15 μm are added to the obtained mixture.  
     
     
         6 . Process according to any of claims  4 - 5 , characterized in that prior to the step of mixing potassium chromate or potassium dichromate or ammonium dichromate is applied in an amount of 1,0-3,5 wt. % from an aqueous solution onto the surface of the oxidizing agent of the fraction with 1-7 μm, and subsequently dried until constant weight is reached.  
     
     
         7 . Process according to any of claims  4 - 6 , characterized in that prior to the step of mixing graphite is applied in an amount of  0,2-0,5  wt. % onto the surface of the oxidizing agent of the fraction with 15-25 μm.