Long unsaturated aliphatic chains as stabilisers for nitrate esters and nitrocellulose-based applications

Abstract

A nitrocellulose-based composition for use as a propellant or as a combustible item is provided. The nitrocellulose-based composition includes a nitrate ester-based component including nitrocellulose; and a stabiliser (I) in the form of a long aliphatic chain having at least two unsaturation sites, the compound having a molecular weight of at least (120) and an iodine number of at least (25).

1 . A nitrocellulose-based composition for use as propellant or as combustible item, said nitrocellulose-based composition comprising:
 (a) a nitrate ester-based component comprising nitrocellulose; and   (b) a stabiliser (I) in the form of a long aliphatic chain having at least two unsaturation sites, the compound having a molecular weight of at least 120 and an iodine number of at least 25.   
     
     
         2 . The nitrocellulose-based composition according to  claim 1 , wherein the nitrate ester-based propellant component consists of nitrocellulose alone (single base) or of a mixture comprising nitrocellulose in combination with at least a blasting oil and/or at least one energetic additive, thus defining a double or higher base composition. 
     
     
         3 . The nitrocellulose-based composition according to  claim 2 , wherein the blasting oil comprises at least a nitrated polyol, which is obtained by nitration of a polyol selected from a group consisting of glycerol, glycol, diethylene glycol, triethylene glycol and metriol. 
     
     
         4 . The nitrocellulose-based composition according to  claim 1 , wherein the stabiliser is a component capable of reacting with both degradation products of the nitrate ester, namely alkoxy radicals and NOx, mainly by a series of hydrogen abstraction of one labile proton of the stabiliser, located in the alpha-position of an unsaturation and recombinations with similar carbon-based free radicals or the NOx species from the ageing of nitrocellulose. 
     
     
         5 . The nitrocellulose-based composition according to  claim 5 , wherein the stabiliser is selected froth one or more of the following components and their derivatives:
 terpenes or terpenoids, including squalene, farnesol, myrcene, thymol, linolenic, carotenoids,   omega 3-6-9 unsaturated fatty acids including one or more of arachidonic acid, linolenic acid, mead acid, herring acid,   triglycerides derived from the above mentioned fatty acids including linseed oil; or   (co-)polymers including polyenes, unsaturated polyester resins, homopolymers copolymers of one or more of butadiene, isoprene, or pentadiene.   
     
     
         6 . The nitrocellulose-based composition according to  claim 5 , wherein the stabiliser consists of a component selected from a group consisting of polybutadiene, polyisoprene, squalene, farnesol, limonene, myrcene, lycopene and citral. 
     
     
         7 . The nitrocellulose-based composition according to  claim 1 , wherein the stabiliser is present in the composition in an amount comprised between 0.1 and 5.0 wt. % with respect to the total weight of the composition. 
     
     
         8 . The nitrocellulose-based composition according to  claim 1 , wherein the nitrate ester-based component comprises not more than 60 wt. % nitroglycerine with respect to the total weight of nitrate ester based propellant. 
     
     
         9 . The nitrocellulose-based composition according to  claim 1 , having a stability measured according to STANAC 4582 (Ed. 1) at a temperature of 90° C. without heat generation above 350 pW/g of at least 3.43 days. 
     
     
         10 . The nitrocellulose-based composition according to  claim 1 , further comprising one or more of the following compounds as complementary stabilisers:
 (a) a substituted phenol compound (2) having the general formula (2-1):   
       
         
           
           
               
               
           
         
       
       wherein : R 6  represents: (i) H, (ii) alkyl substituted or not, or (iii) an al koxy group; and R 7  and R 8  are same or different and represent (i) alkyl substituted or not, or (ii) alkoxy group;
 (b) a trialkoxy benzene (3) having the general formulae (3-1) or (3-II): 
 
       
         
           
           
               
               
           
         
       
       wherein R 9 , R 10  and R 11  are same or different and represent C1-5 alkyl unsubstitute or substituted with an alkoxy group; and
 (c) an aromatic compound (4) having a general formula (4-1): 
 
       
         
           
           
               
               
           
         
       
       wherein : R 12  represents, alkyl-substituted or not; R 13  represent (i) H, (ii) unsaturated alkyl group, 
       
         
           
           
               
               
           
         
         R 14  represents, H, alkyl-substituted or not, or OR 18 ; 
         R 15  represents, alkyl-substituted or not, aromatic ring-substituted or not, or OR 18 ; 
         R 16  represents, alkyl-substituted or not, aromatic ring-substituted or not, or OR 19 ; 
         R 17  represents, aromatic ring-substituted or not; 
         R 18  represents, alkyl-substituted or not, or aromatic ring-substituted; 
         R 19  represents, alkyl-substituted or not, or aromatic ring-substituted. 
         (d) a substituted phenol compound (5) having the general formula (5-1): 
       
       
         
           
           
               
               
           
         
       
       wherein: R 20 , R 21  and R 22  are the same or different and represent: (i) alkyl-substituted or not, (ii) alkoxy group.
 (e) a substituted phenol compound (6) having the general formula (6-1): 
 
       
         
           
           
               
               
           
         
       
       wherein: R 23 , R 24 , R 25  and R 26  are the same or different and represent: (i) alkyl-substituted or not, (ii) alkoxy group. 
     
     
         11 . The nitrocellulose-based composition according to  claim 1  further comprising one or more of the following additives:
 (a) a potassium salt; 
 (b) combustion moderators, such as phthalates, Cl and citrate derivatives; 
 (c) an anti-static agent; 
 and 
 (d) calcium carbonate 
 
       wherein the wt. % are expressed in terms of the total weight of the nitrocellulose-based composition. 
     
     
         12 . Use of a component (I) consisting of a long aliphatic chain having at least unsaturation sites for the stabilization of a nitrate-ester based composition comprising nitrocellulose for applications including propellants and combustible items. 
     
     
         13 . The nitrocellulose-based composition according to  claim 3 , wherein the blasting oil comprises at least a nitrated polyol, which is obtained by nitration of the glycerol. 
     
     
         14 . The nitrocellulose-based composition according to  claim 3 , wherein the at least one energetic additive is an energetic plasticizer selected from a group consisting of: butyl-NENA, and dinitrodiazaalkane (DNDA), or is an explosive selected from a group consisting of: RDX, HMX, FOX-7, FOX-12, CL20, and SMX. 
     
     
         15 . The nitrocellulose-based composition according to  claim 5 , wherein the stabiliser is polybutadiene. 
     
     
         16 . The nitrocellulose-based composition according  claim 1 , wherein the stabiliser is present between 0.2 and 2.0 wt. % with respect to the total weight of the composition. 
     
     
         17 . The nitrocellulose-based composition according  claim 1 , wherein the nitrate ester-based component comprises between 5 and 45 wt nitroglycerine, with respect to the total weight of nitrate ester based propellant. 
     
     
         18 . The nitrocellulose-based composition according  claim 1 , having a stability measured according to STANAC 4582 (Ed. 1) at a temperature of 90° C. without heat generation above 350 pW/g of at least 5 days. 
     
     
         19 . The nitrocellulose-based composition according  claim 11 , wherein the potassium salt is present and in an amount comprised between 0.001 and 1.5 wt. %. 
     
     
         20 . The nitrocellulose-based composition according  claim 11 ., wherein the anti-static agent is present and is graphite.