JPS61101433A - Glass composition for chemical reinforcing - Google Patents

Abstract

PURPOSE:A glass composition for chemical reinforcing having high diffusion rate of K<+>, improved melting properties and molding properties, obtained by blending SiO2 with B2O3, Al2O3, MgO, ZnO, Li2O, Na2O, K2O, and ZrO2 in specific ratios, respectively. CONSTITUTION:A glass composition having basic components consisting of 60-72wt% SiO2, 5-10wt% B2O3, 3-6wt% Al2O3, 5-10wt% MgO, 0-6wt% ZnO, 0-2wt% LiO2, 8-14wt% Na2O, 3-6 K2O, and 3-6 Al2O3+ZrO2 a clarifier (As2O3, Sb2O3, etc.) and a colorant (NiO, CoO, etc.). This glass composition shows high strength by chemically reinforcing treatment, and is easily melted and molded because of low melting and operation points.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a glass composition for chemical strengthening by ion exchange.

[Conventional technology]

Glass is immersed in a molten salt containing alkali metal ions at a temperature below the strain point, and the alkali metal ions in the glass are exchanged with alkali metal ions with a larger atomic radius in the molten salt, producing compressive stress on the glass surface. The so-called chemical strengthening method has been known for a long time. Further, as the alkali metal ions used, Ha+ in the glass is converted into Ha+ in the molten salt.
Replacement with S, S, K15tler (J,
Amer, Ceram, Soc.

VOl, l). Then, in order to speed up the diffusion rate of + in the glass, AJ203 or z was added to the glass.
The inclusion of ro2 is a patent of Corning (
For example, equity W3 tI/-201,29, Tokuko Sho I! 7
- Hiroshi 7970, Tokuko Sho 1-//327, etc.). However, glasses containing a large amount of Al2O3 or ZrO2 have the disadvantage of high melting and forming temperatures.

Improving the meltability of glass and increasing the diffusion rate of +5iO2
69-7I1%, Na2O5-13%p K20 A=
/ 2%.

Na2O 20/J~/9%, 1203'4%
Below, Zr02II% or less, Al2O3+ZrO2
2-7%, MgO 10% or less.

ZnOs% or less, MgO+ZnO2/, 2%, B
2O3 11% or less.

5i02+Na2O+ to 20+Ajl'203+ZrO
It consists of 2+MgO+ZnO+B2O394% or more. However, even with this composition, the melting humidity is still high,
The melting point defined by the viscosity of glass as to2g is 1s
It is 0°C or higher.

[Problem that the invention seeks to solve]

The present invention has a high diffusion rate of + during ion exchange and a melting point of 1! An object of the present invention is to provide a glass composition for chemical strengthening that has excellent meltability and formability at temperatures below 00°C.

[Means for solving problems]

In order to solve the above problems, the glass composition of the present invention is
The basic components indicated by are within the following range.

5i02 60~72 B2o3j~l0 A12033~6 (However, Az2o3+zro2 J
~4) MgO! r~10 zno o~ 6 Li20 0-2 Na20 J ~/4' to 20 3 6 [Function] 5i02 Main component forming the Nigarasu skeleton,
When it is less than 60%, the glass becomes chemically unstable and has poor water resistance and acid resistance, and when it exceeds 72%, its melting temperature becomes high.

B2O3 forms a glass skeleton and lowers the melting temperature and molding temperature of the glass, but 1. If it is less than t%, the effect of lowering the melting temperature will be poor, and if it exceeds 10%, it will melt,
B2O3 tends to volatilize during molding, and defects such as striae and devitrification are likely to occur due to compositional fluctuations.

AA203 In addition to making Nigaras chemically stable,
Promotes ion exchange of + to Na+. If it is less than 3%, the effect of promoting ion exchange will be small, and if it exceeds 6%, the melting temperature of the glass will be high and the glass will be prone to devitrification.

Note that zro2 also has the same effect as Al2O3, so Al2
The range of O3+ZrO2 is also 3 to 6%.

MgO: Reduces the viscosity of the glass at high temperatures without reducing the diffusion rate in the glass, making it easier to melt the glass. If it is less than 5%, the effect is poor, and if it exceeds 10%, the glass tends to devitrify.

ZnOj Improves the meltability of glass like MgO, but is not essential in this application because the meltability is improved by the addition of B2O3 and MgO. However, under conditions where SO3 dissolved in molten glass is reduced in a reducing atmosphere and causes amber coloration, the presence of ZnO in the glass fixes the reduced S as colorless ZnS and prevents amber coloration. , preferably 2% or more.

For example, when glass is formed into a plate shape using 70-Tobath, glass containing 8% is likely to cause amber coloring, but this can be prevented by containing 2% or more of ZnO in the glass. However, ZnO has the disadvantage of making the temperature-viscosity curve of the glass steeper, thereby impairing formability, so its content should not exceed 4%.

It is preferable to contain about 0.3% since it improves the meltability of Li2O Nigarasu, but it is not essential since the raw material is expensive. Moreover, since there is no effect of improving meltability even if the content exceeds 2%, the upper limit is set at 2%.

Na2O: 4% is necessary for ion exchange with + to produce the required compressive stress in the glass surface layer.

However, if it exceeds lψ%, the chemical durability of the glass decreases.

K2O: Coexists with Na2O to promote + diffusion, so at least 3% is required. But 6%
If it exceeds , the alkali gold component in the glass becomes too large,
Reduces the chemical durability of glass.

- In addition to the above components, clarifiers (e.g. AS203ySb203.Se3.C1,
F, etc.), colorants (e.g. Ni0,000.Se, MnO
211Ja2o3 +Pr601, etc.) or impurities may be contained.

〔Example〕

Glass raw materials were prepared to have the composition shown in Table 1, melted in a platinum crucible, cast into a mold, and slowly cooled to obtain a sample. After chemically strengthening the sample glass by immersing it in KNO3 molten salt for 20 hours, the surface compressive stress value was measured. On the other hand, as a measure of the meltability of the glass, the melting point (temperature at which the viscosity of the glass is 102 voids) and working point (the temperature at which the viscosity of the glass is 10' voids) was measured.

The results are shown in Table 1.

Example numbers /-4 in Table 1 are glasses within the glass composition range of the present invention, and Example numbers 7 to 2 are glasses outside the range.

The glasses of Example No./-4 all have high surface compressive stress and the melting point is well below 1600°C, but the glass of Example No. 7 has A6203 + zro2 of 9j%, so it is difficult to carry out the implementation. Example number Zaori's glass is B2O
Since the amount of 3 or MgO is small, the melting point is higher than /jtoq''C, and the working point is also higher than the concave glass of the composition i of the present invention.

〔Effect of the invention〕

The glass of the present invention exhibits higher strength than conventional glasses through chemical strengthening treatment, and has a lower melting point and working point, making it easier to melt and mold.

IRI-

Claims (1)

[Claims] (1) Displayed as a basic component in weight%, SiO_2 60-72 B_2O_3 5-10 Al_2O_3 3-6 MgO 5-10 ZnO 0-6 Li_2O 0-2 Na_2O 8-14 K_2O 3-6 Al_2O_3+ZrO_2 3-6 A glass composition for chemical strengthening having