Process for manufacturing a type and tyre bead structure

A process for forming a bead structure used in manufacturing a tyre comprising:

• (a) winding at least one bare metal wire or cord so as to form a plurality of coils, said coils being radially superimposed and axially arranged side-by-side with respect to one another, to obtain a bead core;
• (b) applying a layer of crosslinkable elastomeric material to the bead core obtained in step (a), to obtain a coated bead core wherein the layer of the crosslinkable material comprises:
• at least one elastomeric polymer;
• at least one rubber-to-metal adhesion promoting additive present in an amount ranging from 0.2 phr to 3 phr;
• and sulfur or derivatives thereof present in an amount ranging from 6 phr to 12 phr;
• (c) partially crosslinking said layer of crosslinkable elastomeric material at a temperature ranging from 125° C. to 150° C. and for a period of time ranging from 10 minutes to 40 minutes, to obtain 50% by weight to 60% by weight free sulfur with respect to the total weight of the sulfur present in said crosslinkable elastomeric material;
• and
• (d) applying a bead filler to the radial outer surface of the bead core obtained in step (c), to obtain a bead structure.