Process and device for cross-linking/expanding a blank for a safety support for a tire and support obtained by this process

Abstract

A process for cross-linking/expanding at least one cross-linkable, expandable blank, which is intended to form all or part of an elastomeric safety support for a tire in which: the cross-linking consists of curing the expandable or expanded blank in a bath of fluid at excess pressure which is contained in an enclosure, such that the blank interacts with the bath independently of the enclosure, the temperature of the bath having a maximum value of between 110° C. and 210° C. and the absolute pressure of said bath having at least a value equal to or greater than 14 bar, and the expansion consists of curing the cross-linkable or cross-linked blank in the bath, the temperature of the bath having a maximum value of between 110° C. and 210° C., and the absolute pressure of the bath having at least a value equal to or greater than 5 bar and a final pressure-relief value substantially equal to 1 bar, for expanding the blank such that its increase in volume is unlimited with respect to the enclosure.

1 . A safety support for mounting on a wheel rime within a tire, at least a section of the support comprising a cross-linked, expanded rubber composition having a cellular structure composed of closed cells, wherein the support or section thereof comprises, radially toward the inside of its outer surface, an intermediate layer, the thickness of which is between 5% and 30% of the smallest dimension of a cross-section through said the support or section, and a core and in which the density of the intermediate layer is less than that of the core.  
   
   
       2 . A support or section of said support according to  claim 1 , having a maximum density in a surface layer at the location of its outer surface, radially to the outside of said intermediate layer.  
   
   
       3 . A support or section of said support according to  claim 1 , having an average density of between 0.04 and 0.4.  
   
   
       4 . A support or section of said support according to  claim 3 , having an average density substantially equal to 0.13.  
   
   
       5 . A support or section of said support according to  claim 1 , having the respective diameters of said cells vary on average from 0.1 mm to 2 mm over a cross-section of said support or section.  
   
   
       6 . A support or section of said support according to  claim 1 , wherein it consists of one or more blanks each of which are based on a copolymer of isoprene and isobutylene.  
   
   
       7 . A support or section of said support according to  claim 1 , wherein it comprises, as reinforcing filler, a blend of 10 to 30 phr silica and 10 to 30 phr carbon black (phr: parts by weight per hundred parts of elastomer(s)).  
   
   
       8 . A support or section of said support according to  claim 1 , comprising a base intended to be mounted on a wheel rim and a crown intended to bear on the tread of said tire following a drop in pressure within the tire, characterized in that it has at least one longitudinal groove extending over said crown substantially level with the latter, in the direction of the length of said support or section of support.  
   
   
       9 . A support or section of said support according to  claim 1 , having at least one longitudinal cutout in its mass, which extends in the direction of the length of said support or section of support.  
   
   
       10 . A support according to  claim 1 , wherein it is substantially in the form of a torus.  
   
   
       11 . A section of a support according to  claim 1 , wherein it is substantially in the form of a portion of a torus.  
   
   
       12 . A section of a support according to  claim 1 , wherein it is substantially of linear form.