Composite pyrotechnic product with crosslinked binder and method for preparing same

Abstract

A composite pyrotechnic product, especially a propellant powder for barrel weapons, containing organic energetic charges in a crosslinked binder, has a composition, expressed as weight percentages, that contains from 78% to 90% of organic energetic charges, and from 10% to 22% of an energetic crosslinked binder obtained by crosslinking, via 8% to 12% of its azide functions, a polyglycidyl azide with a number-average molecular weight of between 700 and 3000 g/mol, with a crosslinking agent containing at least two propargyl functions in its chemical formula, in the presence of a polymeric gum, chosen from polyurethane-polyester gums, polyurethane-polyether gums and mixtures thereof, the number-average molecular weight of which is greater than 20000 g/mol and the Mooney viscosity of which is between 20 and 70 ML (5+4) at 100° C.; the at least one polymeric gum representing from 1% to 5% by weight of the composition of the pyrotechnic product.

1 . A composite pyrotechnic product containing organic energetic charges in a crosslinked binder, wherein a composition of said composite pyrotechnic product, expressed as weight percentages, contains:
 from 78% to 90% of organic energetic charges, and   from 10% to 22% of an energetic crosslinked binder obtained by crosslinking, via only 8% to 12% of its azide functions, a polyglycidyl azide with a number-average molecular weight of between 700 and 3000 g/mol, with at least one crosslinking agent containing at least two propargyl functions in its chemical formula, in the presence of a polymeric gum, chosen from polyurethane-polyester gums, polyurethane-polyether gums and mixtures thereof, a number-average molecular weight of which is greater than 20000 g/mol and a Mooney viscosity of which is between 20 and 70 ML (5+4) at 100° C.; said at least one polymeric gum representing from 1% to 5% by weight of the composition of said pyrotechnic product.   
     
     
         2 . The composite pyrotechnic product as claimed in  claim 1 , wherein said organic energetic charges consist of hexogen, octogen, nitroguanidine, ethylene dinitramine, N-guanylurea dinitramide, 1,1-diamino-2,2-dinitroethylene, bis(triaminoguanidinium) 5,5′-azotetrazolate, dihydrazinium 5,5′-azotetrazolate, 5,5′-bis(tetrazolyl)hydrazine, bis(2,2-dinitropropyl)nitramine, a nitropyrazole, or a mixture of such charges. 
     
     
         3 . The composite pyrotechnic product as claimed in  claim 1 , wherein said organic energetic charges contain ethylene dinitramine charges. 
     
     
         4 . The composite pyrotechnic product as claimed  claim 1 , wherein said polyglycidyl azide has a number-average molecular weight of between 1700 and 2300 g/mol. 
     
     
         5 . The composite pyrotechnic product as claimed in  claim 1 , wherein said at least one crosslinking agent is selected from the group consisting in dipropargyl succinate, dipropargyl maleate, tripropargyl tricarballylate, the benzyl ester of tripropargyl, and a dipropargyl polyethylene glycol with a number-average molecular weight of between 200 and 1500 g/mol. 
     
     
         6 . The composite pyrotechnic product as claimed in  claim 1 , wherein said polymeric gum has a number-average molecular weight of greater than 50000 g/mol. 
     
     
         7 . The composite pyrotechnic product as claimed in  claim 1 , wherein said polymeric gum is a polyurethane-polyester gum or a polyurethane-polyether gum. 
     
     
         8 . The composite pyrotechnic product as claimed in  claim 1 , wherein the composition also contains from 0.1% to 5% by weight of at least one additive. 
     
     
         9 . The composite pyrotechnic product as claimed in  claim 1 , wherein the composite pyrotechnic product consists of a propellant powder for barrel weapons. 
     
     
         10 . A process for preparing at least one composite pyrotechnic product as claimed in  claim 1 , comprising:
 a) providing the ingredients below:   organic energetic charges,   a polyglycidyl azide (PGA) with a number-average molecular weight of between 700 and 3000 g/mol,   at least one agent for crosslinking said polyazide, containing at least two propargyl functions in its chemical formula, and   a polymeric gum, chosen from polyurethane-polyester gums, polyurethane-polyether gums and mixtures thereof, the a number-average molecular weight of which is greater than 20000 g/mol and the a Mooney viscosity of which is between 20 and 70 ML (5+4) at 100° C.;   b) producing a pasty mixture from said ingredients; the organic energetic charges, polyglycidyl azide and polymeric gum being used in suitable proportions relative to the desired composition of the final product, and said at least one crosslinking agent in the amount required for crosslinking from 8% to 12% of the azide functions of said polyglycidyl azide;   c) producing, from said pasty mixture, of at least one element in a desired form; and   d) performing a heat treatment of said at least one element for crosslinking of said polyglycidyl azide.   
     
     
         11 . The process as claimed in  claim 10 , wherein said pasty mixture is prepared with a twin-screw extruder or a two-roll mill. 
     
     
         12 . The process as claimed in  claim 10 , wherein said pasty mixture is prepared at a temperature of between 15° C. and 45° C. 
     
     
         13 . The process as claimed in  claim 10 , wherein said at least one element is obtained by spinning or calendering. 
     
     
         14 . The process as claimed in  claim 10 , wherein said heat treatment is performed at a temperature above 45° C. and below 80° C. 
     
     
         15 . The composite pyrotechnic product as claimed in  claim 1 , wherein the composition, expressed as weight percentages, contains from 80% to 86% of organic energetic charges. 
     
     
         16 . The composite pyrotechnic product as claimed in  claim 3 , wherein said organic energetic charges contain hexogen charges and ethylene dinitramine charges. 
     
     
         17 . The composite pyrotechnic product as claimed in  claim 6 , wherein said polymeric gum has a number-average molecular weight of greater than 75000 g/mol. 
     
     
         18 . The composite pyrotechnic product as claimed in  claim 7 , wherein said polymeric gum is a polyurethane-polyester gum. 
     
     
         19 . The composite pyrotechnic product as claimed in  claim 8 , wherein said at least one additive is selected from formulation agents and plasticizers.