Optical article comprising a hard coat, and production method

A sol-gel composition forming upon cure a coating for (meth)acrylic polymer-based substrates, the sol-gel composition comprising:

• (i) a hard coat solution comprising, by weight relative to its total weight:
• 130 to 230 parts of a silane hydrolysate that is a hydrolysate of an epoxysilane of formula (V):
• wherein:
• R1 is an alkyl group with 1 to 6 carbon atoms,
• R2 is a methyl group or a hydrogen atom,
• a is a whole number from 1 to 6, and
• b is 0, 1 or 2,
• 30 to 800 parts of colloid particles of inorganic oxide, and
• 5 to 20 parts of an aluminum chelate that is a compound formed by reacting an aluminum alcoholate or acylate with at least one nitrogen-and sulphur-free sequestrating agent containing oxygen as the coordinating atom;
• and
• (ii) an adhesion promoter comprising a dendritic polymer having hydroxyl and alkoxysilane groups at terminal ends thereof,
• wherein:
• the dendritic polymer is a hyperbranched polymer or a dendrimer having:
• a degree of functionality in hydroxyl and alkoxysilane of from 5 to 60,
• a number average molar mass Mn ranging from 1000 to 15000g/mol, and
• a functionalization ratio hydroxyl/alkoxysilane ranging from 0.4 to 2.5;
• a content of the adhesion promoter is from 1 to 15% by weight, relative to a total weight of the sol-gel composition;
• and
• the coating for (meth)acrylic polymer-based substrates is an ophthalmic coating.