JPH03223129A - Method for tempering sheet glass - Google Patents

Abstract

PURPOSE:To improve strength by dipping a cellular sintered gel obtained by a sol-gel method in a hydrolytic solution of a metal alkoxide. CONSTITUTION:A wet gel prepared from at least a metal alkoxide or silica particles as main raw material is injected into a hermetically sealed container and gelatinized to provide a gel, which is then dried and heated to afford a cellular sintered gel. The resultant sintered gel is subsequently dipped in a hydrolytic solution of a metal alkoxide to diffuse the aforementioned solution into the vicinity of the surface. The obtained gel is then dried and sintered.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a method for strengthening sheet glass, which enables application to cover glasses of wristwatches, various substrates, and the like.

[Prior Art] Conventional glass strengthening methods include surface treatment by ion exchange, precipitation of microcrystals inside the glass, and surface modification.

[Problems to be Solved by the Invention] However, in the above-mentioned conventional technology, the process becomes complicated and the manufacturing cost increases. Alternatively, introducing other components may cause problems such as loss of original optical properties.

Therefore, an object of the present invention is to provide a method for easily improving the strength of sheet glass while maintaining the properties other than the strength of the base glass.

[Means for Solving the Problems] The method for strengthening sheet glass of the present invention is characterized in that a porous sintered gel obtained by a sol-gel method using at least metal alkoxide or silica particles as a raw material is prepared by hydrolysis of metal alkoxide. A special feature of the present invention is to diffuse a hydrolyzed solution of a metal alkoxide near the surface of a porous sintered gel, and then dry and sinter it. Therefore, compressive stress is generated near the surface of the glass after sintering. Since this occurs on both the front and back surfaces, tensile stress is generated inside, and the strength of the glass plate as a whole is improved.

[Example] Ethyl silicate, ethanol, water, aqueous ammonia (2
9%) were mixed in a molar ratio of 1Nia and 6:4:0.0B, stirred for about 3 hours, and left to stand at room temperature.
The particles were grown and aged. Thereafter, by concentrating under reduced pressure, a silica fine particle dispersion with good dispersibility was prepared.

Next, using ethyl silicate in an amount equal to /4 of the amount of ethyl silicate used above, add 002N hydrochloric acid so that the weight ratio is 1:1, and stir for about 2 hours while cooling with ice to prepare a hydrolyzed solution. did.

Here, the pH value of the silica fine particle dispersion was adjusted to 4.5 by adding 2N hydrochloric acid, and then a hydrolyzed solution of ethyl silicate was mixed therein and sufficiently stirred until a homogeneous liquid sol was obtained. After that, 0.2N ammonia water was added dropwise to the liquid sol, the pH value was adjusted to 5.0, and 60×60×1
The sol was injected into a 5crR box-shaped container. Furthermore, the container was sealed with a lid to form a gel, thereby producing a wet gel. In this state, the linear shrinkage rate of wet gel is 7 to 8%.
The wet gel thus obtained, which was still immersed in the released solvent, was transferred to a drying container and dried in a constant temperature dryer kept at 70°C for about 3 weeks. The drying was completed and a plate-shaped white gel of 46 x 43 x 1.5 cnt was obtained.

The two gel bodies obtained were once heated in an oxygen/nitrogen atmosphere.
After heating to 00°C and cooling to room temperature, one of the gels was immersed in a previously prepared hydrolysis solution of ethyl silicate for 5 hours, dried at 70°C, and then immersed in oxygen / It was heated to 900°C in a nitrogen atmosphere. The purpose of the heat treatment at 900° C. here is to accelerate the condensation reaction of the gel, dehydrate it, and perform various treatments to remove the residues. Further, the gel body after this treatment was insufficiently densified and was porous.

These two gel bodies were further heated to 1350° C. under reduced pressure to vitrify, and then heated to 1750° C. in a nitrogen atmosphere, held for 30 minutes, and then slowly cooled.

The glass body thus obtained was a highly transparent, colorless, plate-like material with a size of approximately 50 x 30 x 1.0 mm.

In addition, the physical properties of the obtained glass include density, coefficient of thermal expansion,
The infrared and near-infrared absorption spectra almost matched those of silica glass.

However, the bending strength measurement results using the three-point support method showed that the glass in which the sintered gel body had been treated had a much larger value.

[Effects of the Invention] As described above, according to the uninvented method, it is easy to improve the mechanical strength of sheet glass.

Therefore, it can be applied to fields that require high strength, such as watch cover glasses, various substrates, and IC packages.

In addition, in the sol preparation step, B, Ti, and Ge.

Na, Oa, Li, At, Te, Zr, Os, Nd, O
It is possible to dope various elements such as r,
It is also easy to produce a variety of multi-component glasses with excellent strength and new glasses that do not have existing compositions.

that's all

Claims (1)

[Claims] At least, a porous sintered gel obtained by a sol-gel method using metal alkoxide or silica particles as a raw material is immersed in a metal alkoxide hydrolysis solution and diffused near the surface. Strengthening method.