Glass frits, a process for their production and their use in enamel barrier layers for stopping the migration of silver

A glass surface having deposited thereon an enamel barrier layer which stops the migration of silver, said layer being formed from a glass frit and optionally one or more colorants and/or opacifiers, said glass frit is essentially free of lead for forming an enamel capable of preventing Ag.sup.+ migration, said glass frit comprising 15 to 70% by weight zinc oxide, 15 to 40% by weight silicon dioxide and 5 to 25% by weight boron trioxide and containing dissolved in said glass 0.05 to 15 mol % of at least one member of the group consisting of sulfur and sulfides.

A method of preventing silver migration into glass comprising placing an enamel barrier layer formed from glass frit and optionally one or more colorants and/or opacifiers between sheet glass and a resistive layer containing silver and firing at a temperature of from 450.degree. C. to 800.degree. C., wherein said glass frit is essentially free of lead for forming an enamel capable of preventing Ag.sup.+ migration, said glass frit comprising 15 to 70% by weight zinc oxide, 15 to 40% by weight silicon dioxide and 5 to 25 % by weight boron trioxide and containing dissolved in said glass 0.05 to 15 mol % of at least one member of the group consisting of sulfur and sulfides.

A composite glass product comprising sheet glass, enamel barrier layer, and silver resistive layer made by a method comprising placing an enamel barrier layer formed from a glass frit and optionally one or more colorants and/or opacifiers between sheet glass and a resistive layer containing silver and firing at a temperature of from 450.degree. C. to 800.degree. C., wherein said glass frit is essentially free of lead for forming an enamel capable of preventing Ag.sup.+ migration said glass frit comprising 15 to 70% by weight zinc oxide, 15 to 40% by weight silicon dioxide and 5 to 25% by weight boron trioxide and containing dissolved in said glass 0.05 to 15 mol % of at least one member of the group consisting of sulfur and sulfides.

A composite glass article comprising a glass support layer, an enamel barrier layer deposited on said glass support layer, and a silver resistive layer deposited on said barrier layer, said enamel barrier layer being formed from a glass frit and optionally one or more colorants and/or opacifiers, wherein said glass frit is essentially free of lead for forming an enamel capable of preventing Ag.sup.+ migration, said glass frit comprising 15 to 70% by weight zinc oxide, 15 to 40% by weight silicon dioxide and 5 to 25% by weight boron trioxide and containing dissolved in said glass 0.05 to 15 mol % of at least one member of the group consisting of sulfur and sulfides.

A process for the production of a glass frit essentially free of lead for forming an enamel capable of preventing Ag.sup.+ migration, said glass frit comprising 15 to 70% by weight zinc oxide, 15 to 40% by weight silicon dioxide and 5 to 25% by weight boron trioxide and containing dissolved in said glass 0.05 to 15 mol % of at least one member of the group consisting of sulfur and sulfides, said process comprises melting a mixture comprising (a) glass forming oxide compounds, or non-oxide compounds which form glass forming oxides, corresponding to 15 to 70% by weight zinc oxide, 15 to 40% by weight silicon dioxide and 5 to 25% by weight boron trioxide and (b) 0.05 to 15 mol % of at least one member of the group consisting of sulfur and sulfides, at a temperature of 1,000.degree. to 1,300.degree. C. to dissolve said sulfur or said sulfides in said glass, cooling suddenly to form granules, and grinding said granules to form a frit.

A glass frit essentially free of lead for forming an enamel capable of preventing Ag.sup.+ migration, said glass frit comprising 15 to 70% by weight zinc oxide, 15 to 40% by weight silicon dioxide and 5 to 25% by weight boron trioxide and containing dissolved in said glass 0.05 to 15 mol % of at least one member of the group consisting of sulfur and sulfides;

• said glass frit being produced by a process comprising melting a mixture comprising (a) glass forming oxide compounds, or non-oxide compounds which form glass forming oxides, corresponding to 15 to 70% by weight zinc oxide, 15 to 40% by weight silicon dioxide and 5 to 25% by weight boron trioxide and (b) 0.05 to 15 mol % of at least one member of the group consisting of sulfur and sulfides, at a temperature of 1,000.degree. to 1,300.degree. C. to dissolve said sulfur or said sulfides in said glass, cooling suddenly to form granules, and grinding said granules to form a frit.