Patent ID: 8323014

Claim:
An expandable bladder for tyre-vulcanising apparatuses, having a toroidal conformation, comprising: at least one first layer of a first elastomer material and one second layer of a second elastomer material different from said first elastomer material; wherein said second layer is at a position radially external to said first layer; wherein said first and second layers are mutually coupled by an undulated interface profile; wherein said interface profile defines mechanical-engagement elements between the first and second elastomer materials; wherein the mechanical-engagement elements result in mechanical engagement between the at least one first layer and the at least one second layer, wherein said undulated interface profile comprises a continuous strip-like element extending around the geometric axis of the bladder according to circumferential coils in side by side relationship, wherein said continuous strip-like element comprises a first and a second elongated elements mutually coupled along their longitudinal extension, each elongated element comprising a base portion and an apex portion, the base portions of the elongated elements being in mutual contact and the apex portions of the elongated elements extending in a substantially transverse direction with respect to the direction of mutual contact between the base portions, and wherein said first and second elongated elements are each one interposed between two mutually opposite sides of the other.