Patent ID: 6881690

Claim:
A lead-free glass flux suitable for coating onto a glazed surface, comprising the following two glass compositions: (a) a glass composition which is essentially free from lead and which comprises, in weight percent, SiO 2 : 45 to 60%, Al 2 O 3 : 5 to 20%, B 2 O 3 : 15 to 30%, and one or more alkali metal oxides: 5 to 10%, provided that Li 2 O is contained in an amount of 2% or more, with the proviso that the total amount of said oxides is 90% or more of the total weight of the composition; and (b) a glass composition which is essentially free from lead and which comprises, in weight percent, SiO 2 : 60 to 75%, Al 2 O 3 : 5 to 20%, at least one of MgO, CaO, ZnO: 5 to 20% in total and one or more alkali metal oxides: 0.5 to 5%, provided that Li 2 O is contained in an amount of 0.5% or more, with the proviso that the total amount of said oxides is 90% or more of the total weight of the composition; wherein the glass compositions (a) and (b) are mixed such that the coefficient of thermal expansion of a glass molded product formed from the flux is 5.5×10 −6 K −1 or less.