Patent ID: 6911500

Claim:
A thermosetting elastomer composition based on modified polycyanurate with improved heat resistance, characterized in that it is obtainable by a process of polymerizing, in the presence of a catalyst (D), a mixture comprising at least: (A) a cyanate, (B) a block copolymer composed of a) at least one central block (B1) which is not miscible with the cyanate and which is sufficiently long to give the composition an elastomeric nature, and b) at least two end blocks (B2) situated either side of the central block and containing groups which are reactive with the cyanate, each of the blocks (B2) being sufficiently long to be miscible with the cyanate, and (C) a mineral filler which is reactive with the cyanate in proportions such that the ratio r is at least 5, but remains below a limit value to prevent phase inversion, said process comprising the steps of: I—mixing (A), (B), (C) and (D) to give a homogeneous mixture at a temperature greater than the melting temperature of (A) and (B) but less than approximately 130° C., II—polymerizing the mixture at a temperature of between approximately 130 and approximately 170° C., III—postcuring the polymerized mixture at a temperature greater than or equal to approximately 200° C., in order to complete the reaction and in that the Δσ rupt and Δε rupt values of the composition thus obtained are less than or equal to ±30%.