Glass plate for tempering

Abstract

Provided is a glass plate for tempering, which is characterized by having a small thermal expansion coefficient under a relatively low temperature, even when the plate is thin, while obtaining a sufficiently high surface compression by the steps involved in conventional thermal tempering. A glass plate for tempering is characterized by having a composition comprising 12.5 to 35 mol% of B2O3; having a composition wherein the difference [X-Y] between the total content X of compound selected from the group consisting of MgO, CaO, BaO, Na2O, and K2O and the total content Y of B2O3 is within a range of -5 to 10 mol%; and being subjected to tempering by heating and quenching.

Description

technical field [0001] The present invention relates to a glass plate for tempering capable of achieving the same or higher strengthening than conventional soda lime glass even when the thickness is thin, and a tempered glass plate obtained by tempering the glass plate. Background technique [0002] Reinforced glass overcomes the technical problem of glass, which is easy to break, and has been used in vehicles and buildings. The tempered glass referred to in the present invention is tempered glass that utilizes heat shrinkage of glass called thermal strengthening or physical strengthening, and refers to windows of vehicles such as passenger cars, trucks, buses, railways, ships, and aircraft. Tempered glass used, tempered glass used for headlights and tail lights, tempered glass used for windows, doors, and showcases of buildings and houses, tempered glass used for furniture such as partition walls, tabletops, bookshelves, and showcases, or office supplies Tempered glass use...

AI Technical Summary

Problems solved by technology

[0006] Regarding the reduction in density of glass, in the case of soda lime silica glass produced by the float process, which is generally used as a glass plate for strengthening, it is about 2.5g / cm at room temperature 3 , moreover, even silica glass is about 2.2g / cm 3 , there is a limit to low density

[0007] On the other hand, regarding the thinning of the thickness of glass, strengthening of glass is known as a technique capable of overcoming a decrease in strength. In thermal strengthening of glass, the temperature difference between the surface and the inside of the glass during cooling is used for strengthening. Therefore, in In the case of thin glass of 2.8 mm or less, it is difficult to strengthen due to temperature difference

As a thermally strengthened glass plate, when the temperature difference between the temperature near the yield point at which thermal strengthening begins and the strain point where the strain freezes is large, or when the coefficient of linear thermal expansion at high temperatures near the yield point is large, strengthening is easy It is preferable to carry on, but this kind of glass has a large linear thermal expansion coefficient from low temperature, so it is not suitable for the case where the linear thermal expansion coefficient at a relatively low temperature is desired to be small according to the application.

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