Aromatic polysulphone coated article and bonded structure

Claim 1

A solid surface hving a baked on, substantially crosslinked coating formed from an adhesive composition comprising an aromatic polysulphone whose number average molecular weight is sufficiently high to give a reduced viscosity of at least 0.3 (measured at 25°C on a solution in dimethyl formamide containing 1 g of polymer in 100 cm 3 of solution) and which contains at least 0.2 aromatically bound hydroxy end-groups per 100 polymer repeat units, said coating being characterized by its increased adhesion to said surface as evidenced by increased shear strength compared with the case where said coating is formed from a similar polysulphone with less than the indicated number of aromatically bound hydroxyl groups, the polysulphone being crosslinked at the molecular weight thereof being increased subsequent to coating by baking the coating in the presence of oxygen, said increased molecular weight and substantial crosslinking being evidenced by the insolubility of the baked polysulphone coating in dimethyl fomamide at 25°C compared with the solubility of the aromatic polysulphone in the non-baked coating and the solubility of the aromatic polysulphone when baked in the absence of air under otherwise comparable conditions.