Rubber composition which is free of carcinogenic nitrosamine precursor and serves as connecting rubber

Abstract

A rubber composition which is free of precursor of at least one carcinogenic nitrosamine, is capable of vulcanization at a temperature of between 95° C. and 140° C., and has a vulcanization system which includes: a) sulfur; b) an accelerator compound; c) an ultra-accelerator compound; d) a vulcanization amine activator. A process for vulcanizing this composition in the manufacture of a new tire or in the repair and/or recapping of a worn tire.

We claim:  
     
         1 . A composition which is free of precursor of at least one carcinogenic nitrosamine containing at least one rubber selected from the group consisting of natural rubber, polyisoprene, polybutadiene, styrene-butadiene, styrene-isopreneland butadiene-isoprene copolymers, and styrene-butadiene-isoprene terpolymers, and capable of vulcanizing at a temperature between 95° C. and 140° C., characterized by the fact that it comprises, as vulcanization system: 
 a) sulfur;  
 b) at least one accelerator compound selected from the group consisting of benzothiazyl disulfide and mercaptobenzothiazole;  
 c) at least one ultra-accelerator compound selected from the group consisting of tetrabenzylthiuram disulfide and zinc dibenzyldithiocarbamate;  
 d) at least one vulcanization amine activator selected from the group consisting of amines, guanidines, aldehyde and amine condensates, and quaternary ammonium salts.  
 
     
     
         2 . A composition according to  claim 1 , characterized by the fact that it contains natural rubber or a mixture of natural rubber and at least one other rubber selected from the group consisting of polyisoprene polybutadiene, styrene-butadiene, styrene-isoprene, and butadiene-isoprene copolymers, and styrene-butadiene-isoprene terpolymers.  
     
     
         3 . A composition according to  claim 1 , characterized by the fact that it contains at least one additive selected from the group consisting of carbon blacks, extender oils, and tackiness agents.  
     
     
         4 . A composition according to  claim 1 , characterized by the fact that, for 100 parts by weight of the rubber or all the rubbers, the amount of sulfur is between 0.5 and 5 parts by weight.  
     
     
         5 . A composition according to  claim 4 , characterized by the fact that, for 100 parts by weight of the rubber or of all the rubbers, the amount of sulfur is between 1 and 3 parts by weight.  
     
     
         6 . A composition according to  claim 1 , characterized by the fact that, for 100 parts by weight of the rubber or all the rubbers, the amount of compound b) or all the compounds b) is between 0.1 and 3 parts by weight.  
     
     
         7 . A composition according to  claim 6 , characterized by the fact that, for 100 parts by weight of the rubber or of all the rubbers, the amount of compound b) or all compounds b) is between 0.2 and 2 parts by weight.  
     
     
         8 . A composition according to  claim 1 , characterized by the fact that, for 100 parts by weight of the rubber or all the rubbers, the amount of compound c) or all the compounds c) is between 0.2 and 3 parts by weight.  
     
     
         9 . A composition according to  claim 8 , characterized by the fact that, for 100 parts by weight of the rubber or all the rubbers, the amount of compound c) or all compounds c) is between 0.4 and 2 parts by weight.  
     
     
         10 . A composition according to  claim 1 , characterized by the fact that, for 100 parts by weight of the rubber or all the rubbers, the amount of compound d) or of all compounds d) is between 0.05 and 1 part by weight.  
     
     
         11 . A composition according to  claim 10 , characterized by the fact that for 100 parts by weight of the rubber or all the rubbers, the amount of compound d) or of all compounds d) is between 0.1 and 0.5 parts by weight.  
     
     
         12 . A composition according to  claim 1 , characterized by the fact that it comprises diphenylguanidine as compound d).  
     
     
         13 . A composition according to  claim 1 , characterized by the fact that it is capable of vulcanizing at a temperature of between 95° C. and 115° C.  
     
     
         14 . A composition according to  claim 1 , characterized by the fact that it is intended to be used in order to connect two prevulcanized parts of rubber, the composition serving as connecting rubber between said parts.  
     
     
         15 . A composition according to  claim 14 , characterized by the fact that it is intended to be used in order to manufacture a new tire.  
     
     
         16 . A composition according to  claim 14 , characterized by the fact that it is intended to be used in order to repair and/or recap a worn tire.  
     
     
         17 . A process consisting of vulcanizing a composition according to  claim 1  at a temperature of between 95° C. and 140° C.  
     
     
         18 . A process according to  claim 17 , characterized by the fact that the vulcanization is carried out at a temperature between 95° C. and 115° C.  
     
     
         19 . A process according to  claim 17 , characterized by the fact that it includes vulcanizing the composition to connect two prevulcanized parts of rubber, the composition serving as connecting rubber between said parts.  
     
     
         20 . A process according to  claim 19 , characterized by the fact that it includes vulcanizing the composition in the manufacture of a new tire.  
     
     
         21 . A process according to  claim 19 , characterized by the fact that it includes vulcanizing the composition in the repair and/or recapping of a worn tire.