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AssigneeAGC Inc.
InventorsSuguru Murayama, Satoshi Kanasugi, Madoka Ono
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A glass for chemical strengthening has a Young's modulus E of 70 GPa or more. The glass satisfies X1+X2+X3 being 1760 or less. Here, X1 is a numerical value equivalent to a value [unit: kPa/° C.] obtained by multiplying the Young's modulus E by an average coefficient α of thermal expansion at 50° C. to 350° C., X2 is a numeral value equivalent to a value of a temperature Tf [unit: ° C.] at which a viscosity of the glass reaches 100 MPa·s, and X3 is a numerical value equivalent to a value of a difference [unit: 105 Pa·s] between the viscosity (100 MPa·s) at the Tf and a viscosity η+10 at a temperature 10° C. higher than the Tf.
A glass for chemical strengthening, having a Young's modulus E of 70 GPa or more, and satisfying X1+X2+X3 being 1760 or less,
A glass for chemical strengthening, having a Young's modulus E of 80 to 90 GPa and an average coefficient α of thermal expansion at 50° C. to 350° C. of 60×10−7 to 85×10−7/° C., and
A chemically strengthened glass, having a curved surface shape by bend-forming, and
Dependencies are inferred from the claim text.
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With 40% to 90% silica, by weight: containing aluminium oxide or an iron compound
By press-bending between shaping moulds: between opposing full-face shaping moulds
Containing aluminium oxide or an iron compound: containing an oxide of a divalent metal
Containing an oxide of a divalent metal: containing calcium oxide, e.g. common sheet or container glass
About 13 years 1 month of term left · ends 2 Dec 2039 (estimated)
The present invention relates to a glass for chemical strengthening and a chemically strengthened glass, and further relates to a method for manufacturing a chemically strengthened glass.
Thin and high-strength chemically strengthened glasses are used as cover glasses for display devices of mobile devices such as mobile phones and smart phones and cover glasses for onboard display members such as instrument panels and head-up displays (HUDs). In these display devices, a cover glass having a curved surface shape is sometimes required to improve operability and visibility. The cover glass having the curved surface shape can be produced by heating a flat glass sheet and bend-forming it into the curved surface shape using a forming mold (also referred to as three-dimensional forming) (see Patent Literature 1).
Patent Literature 2 discloses a lithium aluminosilicate glass having a glass transition temperature of 550° C. or less and capable of being subjected to three-dimensional forming and chemical strengthening.
FIG. 1 is a schematic view of a device used for bend forming of a glass sheet as one example.
FIG. 2 is a diagram schematically showing how a periphery of a fracture starting point is cracked in the case where a glass having no residual stress inside is fractured by uniform tensile stress.
A glass for chemical strengthening and chemically strengthened glass in the present invention are described below.
In the present description, the “chemically strengthened glass” means a glass after having been subjected to a chemical strengthening treatment. On the other hand, the “glass for chemical strengthening” means a glass before being subjected to a chemical strengthening treatment. The “glass for chemical strengthening” is a glass capable of being chemically strengthened.
In the present description, the “base composition of the chemically strengthened glass” is a glass composition of the glass for chemical strengthening. In the chemically strengthened glass, a compressive stress layer due to ion exchange is usually formed in a glass surface layer. Therefore, the glass composition of a portion not ion-exchanged matches the base composition of the chemically strengthened glass.