Process of preparation of amino functionalized diene polymers, polymers of such type, rubber composition and tire casing containing those polymers

Abstract

The present invention provides a process for preparing amino functionalized diene polymers with 1,4-trans linkage content equal to or greater than 70%. The invention also concerns polymers of such type, a rubber composition and a tire casing containing those polymers. The process of preparation according to the invention comprises polymerizing at least one diene monomer by means of a lithium catalytic system, which comprises at least one hydrocarbon solvent, one compound A of a IIIA group metal, one compound B of an alkaline earth metal and one aminolithium initiator C. Amino functionalized diene polymers with high 1,4-trans linkage content according to the invention are such that the amino function, situated at the end of the polymer chain, is a tertiary amino function, the rate of functionalization of said polymers being equal to or greater than 50% and the 1,4-trans linkage content being equal to or greater than 70%. A rubber composition vulcanizable with sulfur according to the invention is such that it contains at least said polymer. A tire casing according to the invention is such that it contains said composition.

1 . An amino-functionalized diene polymer having a high 1,4-trans linkage content and an amino function situated at an end of the polymer chain, 
 wherein the amino function is a grafted noncyclic or cyclic tertiary amino function, such that the end of the polymer corresponds to the formula:                          wherein R 1  and R 2  are each an alkyl group, the number of carbon atoms of the R 1  and R 2  set ranging from 2 to 15, n being the whole number ranging from 2 to 15, 
 the functionalization rate of said polymer is equal to or greater than 50%, and  
 the 1,4-trans linkage content is equal to or greater than 70%.  
   
   
   
       2 . The amino-functionalized diene polymer according to  claim 1 , prepared by a process which comprises contacting a diene monomer with a catalyst system consisting essentially of at least one hydrocarbon solvent, a compound A of a group IIIA metal, a compound B of an alkaline earth metal, and an aminolithium initiator C.  
   
   
       3 . The amino-functionalized diene polymer according to  claim 2 , wherein compound A is a trialkyl aluminum, compound B is a barium or calcium or strontium alcoholate, and initiator C is a lithium amide or a polymer obtained by anionic means which presents a C—Li bond and an amino function group.  
   
   
       4 . A rubber composition vulcanizable with sulfur, containing a reinforcing filler, wherein said composition comprises at least one polymer according to  claim 1 .  
   
   
       5 . A tire casing comprising a composition according to  claim 4.