Patent ID: 8440740

Claim:
A hardening composition comprising (i) a particulate glass and (ii) an acidic copolymer reactive with the particulate glass under aqueous conditions, characterized in that said particulate glass comprises a. 10-35% by weight of silica b. 10-35% by weight of alumina c. 3-30% by weight of zinc oxide d. 4-30% by weight of P 2 O 5 e. 3-25% by weight of fluoride, and said acidic copolymer has a mean molecular weight, M w , of from 50,000 to 200,000 and is obtainable by a process comprising the copolymerization of a mixture containing the following acids or hydrolysable derivatives thereof (1) acrylic acid, and (2) a compound of the following formula (II): wherein n is an integer of from 1 to 3, wherein said acidic copolymer has an acrylic acid to compound of formula II ratio between 98/2 and 85/15.