HIGH PERFORMANCE COMPOSITE PYROTECHNIC PRODUCT WITHOUT Pb IN ITS COMPOSITION, AND PREPARATION THEREOF

Abstract

A high performance composite pyrotechnic product without lead in its composition, and that can be obtained on an industrial scale without encountering a problem of potlife for the intermediate paste, the product containing organic energetic charges and a combustion catalyst in a plasticized binder including a cured energetic polymer and at least one energetic plasticizer. In characteristic manner, the cured energetic polymer consists of a glycidyle azide polymer (GAP) having number average molecular weight (Mn) lying in the range 700 g/mol to 3000 g/mol, cured via its hydroxyl terminal functions with at least one curing agent of polyisocyanate type; and the combustion catalyst consists of bismuth citrate.

1 . A composite pyrotechnic product containing organic energetic charges and a combustion catalyst in a plasticized binder comprising a cured energetic polymer and at least one energetic plasticizer, wherein:
 said cured energetic polymer consists of a glycidyle azide polymer (GAP) having number average molecular weight (Mn) lying in the range 700 g/mol to 3000 g/mol, cured via its hydroxyl terminal functions with at least one curing agent of polyisocyanate type; and   said combustion catalyst consists of bismuth citrate.   
     
     
         2 . The composite pyrotechnic product according to  claim 1 , wherein said glycidyle azide polymer (GAP) has number average molecular weight (Mn) lying in the range 1700 g/mol to 2300 g/mol. 
     
     
         3 . The composite pyrotechnic product according to  claim 1 , wherein said at least one energetic plasticizer is of the nitrate and/or nitramine type. 
     
     
         4 . The composite pyrotechnic product according to  claim 1 , wherein said organic energetic charges are selected from:
 hexogen, octogen, hexanitrohexaazaisowurtzitane, nitroguanidine, ethylene dinitramine, N-guanylurea dinitramide, 1,1 -diamino-2,2-dinitro ethylene, bis(triaminoguanidinium)-5,5′-azotetrazolate, dihydrazinium 5,5′-azotetrazolate, 5,5′-bis(tetrazolyl)hydrazine, bis(2,2-dinitropropyl) nitramine, and nitropyrazole charges, and mixtures of such charges.   
     
     
         5 . The composite pyrotechnic product according to  claim 1 , containing 1% to 6% by weight, of said bismuth citrate. 
     
     
         6 . The composite pyrotechnic product according to of  claim 1 , further containing at least one additive. 
     
     
         7 . The composite pyrotechnic product according to  claim 6 , wherein said at least one additive comprises at least one curing catalyst and/or at least one stabilizer agent for said at least one energetic plasticizer. 
     
     
         8 . The composite pyrotechnic product according to  claim 1 , wherein in that its composition contains the following, expressed in percentages by weight:
 50% to 70% of said organic energetic charges;   10% to 14% of said cured energetic polymer;   10% to 30% of said at least one energetic plasticizer;   1% to 6%, of said bismuth citrate; and   0 to 4%, of at least one additive.   
     
     
         9 . A method of preparing a composite pyrotechnic product according to  claim 1 , comprising:
 preparing a homogeneous paste by:
 a) incorporating, at a temperature lying in the range 35° C. to 55° C., in said glycidyle azide polymer, said at least one energetic plasticizer, organic energetic charges, and other ingredients constituting said desired composite pyrotechnic product with the exception of any curing agent and any curing catalyst; and 
 b) stirring the resulting mixture under a partial vacuum at a temperature lying in the range 35° C. to 55° C.; 
   under a partial vacuum, at a temperature lying in the range 35° C. to 55° C., incorporating in said resulting homogeneous paste, said at least one curing agent and optionally at least one curing catalyst, followed by stirring the resulting mixture;   casting said stirred resulting mixture in at least one structure; and   heat treating said cast stirred resulting mixture in said at least one structure.   
     
     
         10 . The composite pyrotechnic product according to  claim 5 , containing 3% to 5% by weight of said bismuth citrate. 
     
     
         11 . The composite pyrotechnic product according to  claim 8 , wherein its composition contains, expressed in percentages by weight, 55% to 65% of said organic energetic charges. 
     
     
         12 . The composite pyrotechnic product according to  claim 8 , wherein its composition contains, expressed in percentages by weight 15% to 25% of said at least one energetic plasticizer. 
     
     
         13 . The composite pyrotechnic product according to  claim 8 , wherein its composition contains, expressed in percentages by weight, 3% to 5% of said bismuth citrate. 
     
     
         14 . The composite pyrotechnic product according to  claim 8 , wherein its composition contains, expressed in percentages by weight, 0.1% to 4% of said at least one additive.