Glass Articles with Improved Chemical and Mechanical Durability

Abstract

A glass article may formed from a glass composition that may include from about 70 mol. % to about 78 mol. % SiO₂, from about 3 mol. % to about 13 mol. % alkaline earth oxide, X mol. % Al₂O₃, and Y mol. % alkali oxide. The alkali oxide may include Na₂O in an amount greater than or equal to about 9 mol. % and less than or equal to about 15 mol. %. The ratio of Y:X may be greater than 1. The glass article may be free of boron and compounds of boron. The glass article may have a compressive stress layer with a compressive stress greater than or equal to about 250 MPa and depth of layer greater than or equal to about 25 μm. The glass article may have at least a type HGA2 hydrolytic resistance according to the ISO 720 standard.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]The present application claims priority to U.S. Provisional Patent Application Ser. No. 61 / 551,163, filed Oct. 25, 2011 (Attorney Docket No. SP11-240P) and entitled “Glass Compositions With Improved Chemical and Mechanical Durability,” the entirety of which is incorporated by reference herein.BACKGROUNDField[0002]The present specification generally relates to glass articles and, more specifically, to chemically and mechanically durable glass articles.Technical Background[0003]Historically, glass has been used as a preferred material for many applications, including food and beverage packaging, kitchen and laboratory glassware, and windows or other architectural features, because of its hermeticity, optical clarity and excellent chemical durability relative to other materials. For various applications, glass articles must have acceptable chemical durability, which often depends on the context in which the glass article is used. For example...

AI Technical Summary

Benefits of technology

[0008]According to one embodiment, a glass article may be formed from a glass composition comprising from about 70 mol. % to about 78 mol. % SiO2, from about 3 mol. % to about 13 mol. % alkaline earth oxide, X mol. % Al2O3, and Y mol. % alkali oxide. The alkali oxide may comprise Na2O in an amount greater than or equal to about 9 mol. % and less than or equal to about 15 mol. %. The ratio of Y:X may be greater than 1. The glass article may be free of boron and compounds of boron. The glass article may comprise a compressive stress layer with a compressive stress greater than or equal to about 250 MPa and depth of layer greater than or equal to about 25 μm. The glass article may have at least a type HGA2 hydrolytic resistance according to ISO 720.

Problems solved by technology

However, use of glass for many applications is limited by the mechanical performance of the glass.

Additionally, in the food and beverage packaging industry, glass breakage is a safety concern for the end user as the broken package and / or the contents of the package may injure the end user.

Breakage can be costly to many food or beverage packaging industries because, for example, breakage within a filling line may require that neighboring unbroken containers be discarded as the containers may contain fragments from the broken container.

Breakage may also require that the filling line be slowed or stopped, lowering production yields.

Further, non-catastrophic breakage (i.e., when the glass cracks but does not break) may cause the contents to lose their sterility which, in turn, may result in costly product recalls.

However, for many glass article applications it is desirable or required to have complex geometries, thin walls (˜1-1.5 mm), and are produced from low expansion glasses (30-55×10−7K−1) making many glass articles unsuitable for strengthening by thermal tempering.

However, glass compositions which exhibit a moderate susceptibility to chemical tempering generally exhibit poor chemical durability and vice-versa.

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