Coupling agent for an elastomeric composition comprising a reinforcing filler

Abstract

Coupling agent consisting of a combination of: 10 to 90% of a blend of poly(alkylphenol) polysulfides of formula: in which: R is an alkyl radical containing 1 to 20 carbon atoms; n and n′ are two integers from 1 to 8; p is an integer from 0 to 50; and 10 to 90% of bis(triethoxysilylpropyl)tetra-sulfide. Reinforcing filler-containing vulcanizable elastomeric composition using this. Molded article obtained by forming and heating the composition.

1 . A sulfur-vulcanizable elastomeric composition comprising at least one diene elastomer and at least one reinforcing filler obtained by a process comprising mixing of said elastomer and said filler with an effective amount of a coupling agent consisting of a combination of 
 10 to 90%, of a product (I) consisting of a blend of poly(alkylphenol) polysulfides of formula                          in which:    R is an alkyl radical containing 1 to 20, carbon atoms;    n and n′ are two integers, which may be identical or different, from 1 to 8;    p is an integer from 0 to 50; and    10 to 90%, of a product (11) consisting of bis(triethoxysilylpropyl)tetrasulfide.    
   
   
       2 . The elastomeric composition as claimed in  claim 1 , characterized in that one or more diene elastomers chosen from polybutadiene and poly(styrene/butadiene) are used.  
   
   
       3 . The elastomeric composition as claimed in  claim 1 , characterized in that a white reinforcing filler is used.  
   
   
       4 . The elastomeric composition as claimed in  claim 3 , characterized in that the white filler is silica, by itself or as a mixture with alumina.  
   
   
       5 . The elastomeric composition as claimed in  claim 1 , characterized in that a mixture of compounds of formula (I) is used in which R is an alkyl radical containing at least one tertiary carbon via which R is linked to the aromatic ring.  
   
   
       6 . The elastomeric composition as claimed in  claim 5 , characterized in that R is a tert-butyl or tert-pentyl radical.  
   
   
       7 . The elastomeric composition as claimed in  claim 1 , characterized in that, in said blend of compounds of formula (1), a mixture is used in which the average value of n and of n′ is about 2 and the average value of p is about 5.  
   
   
       8 . The elastomeric composition as claimed in  claim 1 , characterized in that the (1)/(11) weight ratio is from 1 to 3.  
   
   
       9 . The elastomeric composition as claimed in one of  claim 3 , characterized in that it is obtained by mixing, with 100 parts by weight of diene elastomer(s): 
 10 to 200, parts by weight of white reinforcing filler; and    0.5 to 10, parts by weight of said coupling agent as defined above.    
   
   
       10 . The elastomeric composition as claimed in  claim 9 , characterized in that 50 to 100 parts by weight of silica and 5 to 7 parts by weight of the coupling agent are mixed with 100 parts by weight of said at least one diene elastomer.  
   
   
       11 . The elastomeric composition as claimed in  claim 1 , characterized in that non-sulfur-containing additives are incorporated.  
   
   
       12 . The elastomeric composition as claimed in  claim 11 , characterized in that the diene elastomer, the reinforcing filler, the products (I) and (II) and the non-sulfur-containing additives are subjected to mechanical working, including at least one thermal step at a temperature of between 130° C. and 170° C.  
   
   
       13 . The elastomeric composition as claimed in  claim 11 , characterized in that a vulcanization system comprising sulfur and vulcanization accelerators is added by mechanical working.  
   
   
       14 . (canceled)  
   
   
       15 . A molded article obtained by forming the composition as defined in  claim 13  followed by heating.  
   
   
       16 . The molded article as claimed in  claim 15 , characterized in that it is a tire tread.  
   
   
       17 . The elastomeric composition of  claim 1 , comprising 50 to 70% of said product (I).  
   
   
       18 . The elastomeric composition of  claim 1 , characterized in that R contains 4 to 10 carbons atoms.  
   
   
       19 . The elastomeric composition of  claim 1 , characterized in that n and n′ are form 1 to 4  
   
   
       20 . The elastomeric composition of  claim 1 , comprising 30 to 50% of said product II.  
   
   
       21 . The elastomeric composition of  claim 8  characterized in that the ratio (I)/(II) is about 2.  
   
   
       22 . The elastomeric composition of  claim 9  comprising between 20 and 150 parts by weight said white reinforcing filler.  
   
   
       23 . The elastomeric composition of  claim 9  comprising 2 to 8 parts by weight of said coupling agent.  
   
   
       24 . The elastomeric composition of  claim 12  characterized in that said temperature is between 130° and 150°.  
   
   
       25 . A coupling agent comprising a combination of: 
 10 to 90%, of a product (I) consisting of a blend of poly(alkylphenol) polysulfides of formula:                          in which:    R is an alkyl radical containing 1 to 20, carbon atoms;    n and n′ are two integers, which may be identical or different, from 1 to 8;    p is an integer from 0 to 50; and    10 to 90%, of a product (11) consisting of bis(triethoxysilylpropyl)tetrasulfide.    
   
   
       26 . The elastomeric composition as claimed in  claim 25 , characterized in that a mixture of compounds of formula (I) is used in which R is an alkyl radical containing at least one tertiary carbon via which R is linked to the aromatic ring.  
   
   
       27 . The elastomeric composition as claimed in  claim 25 , characterized in that the (I)/(II) weight ratio is from 1 to 3.  
   
   
       28 . The elastomeric composition of  claim 27  characterized in that the ratio (I)/(II) is about 2.