JP2000233949A - Chemically reinforcing treatment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the damage at the time of handling at a low cost by applying a reinforcing salt solution, in which a thickener is added, on the optional part such as the edge end surface of a glass plate product and heat treating it to introduce a chemically reinforced layer on the surface of the glass to efficiently reinforce the glass at high productivity. SOLUTION: Only a part necessary for being reinforced in the glass plate product, particularly the edge part is coated with the reinforcing salt solution, in which the thickener is added to be about 0.01-1,000 poise in viscosity and heat treated at a temp. equal to or below the glass transition temperature of the glass after dried. The reinforcing salt in the reinforcing salt solution is constituted of nitrate, chloride, peroxide salt, perchlorate or the like of an alkali metal. As the thickener, a food additive base or the derivative such as curdlan, cellulose is used. The glass is reinforced by ion-exchanging between the glass and the reinforcing salt by the heat treatment to form a compressive stress layer on the glass inner surface. The reinforcing treatment is preferably continuously applied using a belt conveyer in the production line of a glass substrate or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The chemical strengthening solution is applied only to the end face of a glass substrate for a plasma display or a liquid crystal display, and then heat-treated, and the end face is chemically strengthened, so that cracks develop from the end face and chipping occurs. This is to prevent the generation of particles due to

[0002]

2. Description of the Related Art In general, glass is a brittle material, and its handling is very delicate. The glass is manufactured by generating cracks from the glass end face due to physical impact during glass handling or generating particles due to chipping. Sometimes it leads to breakage or failure.

Conventionally, the tempering treatment of glass is generally performed by air-cooling to leave thermal stress in the glass. However, the air-cooling treatment is performed by thermally cooling the glass in the thickness direction to be strengthened. Due to the difference in speed, tensile stress inside the glass,
This method is a physical strengthening method in which a compressive stress remains on the surface. However, as the thickness of a glass product has been reduced, the strengthening method by air-cooling has become difficult.

[0004] In particular, when the thickness of the glass is reduced to 1.5 mm or less, there is little difference in cooling speed in the thickness direction of the glass, and the temperature becomes instantaneously uniform. And it is more difficult to strengthen the air cooling. Therefore, a chemical strengthening treatment method of introducing a compressive stress layer to the surface of a glass sheet by thermally exchanging alkali ions on the glass surface with alkali ions having a larger atomic radius than the alkali ions was developed. . In particular, since the chemical strengthening treatment method can perform the strengthening process without being limited by the thickness and shape of the glass to be strengthened, it is a very effective means for strengthening the thin glass and the glass having a complicated shape. It has become.

[0005]

However, in order to perform the chemical strengthening process, a salt bath for the strengthening process is required according to the shape of the glass to be strengthened. Equipment is required. Further, the chemical strengthening treatment is generally performed in a batch system, and tends to be avoided due to productivity and cost problems.

In the present invention, there is provided a method for overcoming the drawbacks of the above-described chemical strengthening treatment, efficiently performing the chemical strengthening treatment, enabling continuous chemical strengthening treatment, improving productivity and reducing costs. The task is to provide.

[0007]

Means for Solving the Problems The present inventors have conducted intensive studies on the above-mentioned problems, and as a result, have found that the above-mentioned problems are achieved, and have completed the present invention.

That is, the tempering treatment of glass is a method applied to increase the physical strength of the glass itself, but it is also a very effective method for preventing breakage during handling in production and manufacturing processes. In the latter case, all of the damages are damages due to contact, such as chipping or crack progress at the edge of the end face, and there are very few cases where breakage occurs due to generation of an origin other than at the edge of the end face. That is, it can be said that the portion of the glass sheet product or the glass substrate that requires the strengthening treatment is located particularly at the edge of the end face. Therefore, in the present invention, by introducing a strengthening layer only to this end face portion by a chemical strengthening treatment method different from the conventional one, prevention of breakage during handling in the production and manufacturing process of glass sheet products and glass substrates, and further breakage It is characterized in that particles are prevented from being generated due to chipping at the time.

By utilizing the present invention, it is possible to continuously and easily perform chemical strengthening treatment in the production and manufacturing processes of window glass, glass sheet products for automobiles, and glass substrates for plasma displays and liquid crystal displays. It is thought that this leads to prevention of product damage and cost reduction.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

The solution temperature of the fortifying salt solution used in the present invention can be used at room temperature to 100 ° C. or lower, but is preferably maintained at 30 ° C. to 80 ° C. for use. This temperature range is necessary for preventing the liquid dripping of the applied portion when the fortifying salt solution is applied and for quickly drying.
It is even more preferable to dry using hot air after the application of the reinforcing salt solution.

It is also possible to prevent liquid dripping by increasing the amount of the thickener added. The amount of the thickener to be added must be from 0.01 poise to 1000 poise in solution viscosity after the addition. If it is less than 0.01 poise, the amount of the reinforcing salt adhering to the coated portion is small, and a sufficient reinforcing treatment cannot be performed. Conversely, at 1000 poise or more,
The carbonization of the strengthening salt solution during the heat treatment is remarkable, and there is a risk that the thermal diffusion of alkali ions in the strengthening salt may be hindered, which is not preferable. Unnecessarily attaching the fortifying salt solution causes dripping of the fortifying solution during drying or heat treatment,
Enhancements may be introduced beyond what is desired.

The fortifying salt in the fortifying salt solution mainly comprises nitrates, chlorides, peroxides and perchlorates of alkali metals. For example, a compressive stress layer is formed on the inner surface of glass by ion exchange between sodium in the glass and potassium in the strengthening salt solution, or by exchange of sodium or lithium in the glass with sodium or potassium ion in the strengthening salt solution. As a result, the glass is strengthened. Examples include the following fortified salt solutions.

Distilled water 50-90 parts Potassium nitrate 7-15 parts Sodium nitrate 2-10 parts Potassium chloride 4-10 parts Sodium chloride 2-8 parts Potassium chlorate 0.5-5 parts Sodium chlorate or hypochlorous acid Sodium 0.5-5 parts Thickener 0.1-5 parts were mixed and adjusted.

[0015] In particular, the thickener is not limited to the kind,
If it is 0.1 part or less and 5 parts or more, there is a danger that the strengthening salt will flow down or carbonize significantly during the heat treatment of the substrate after the application of the strengthening salt, the ion exchange action is hindered, and a predetermined strengthening layer cannot be formed. Representative thickeners include the following food additive systems, or derivatives thereof.

Curdlan, cellulose, cassia gum, casein, cassia gum, gaddy gum, carrageenan, carrageenan, karaya gum, carob bean gum, xanthan gum, xanthan polysaccharide, chitin, chitosan, guar gum, guar flower, guar gum, glucosamine, gluten, kelp extract, kelp Mucilage, psyllium, psyllium seed gum, psyllium husk, gazein, xanthan gum, gellan, gellan gum, gellan polysaccharide, sclero gum, scleroglucan, fibrin glycol, tamarind, tamarind gum, tamarind seed gum, tara gum, dimple glycol , Tragacanth, tragacanth gum, triacanthos, triacanthos gum, trolloa

The mixing ratio of distilled water and each salt must be changed depending on the composition of the glass to be strengthened or the roughness of the surface.

The chemically strengthened layer is introduced by applying the strengthened salt solution in the above-mentioned predetermined region thinly to the portion of the glass to be strengthened which needs to be strengthened, drying and heat-treating the glass at the transition temperature or lower. The heat treatment temperature and time vary depending on the composition of the glass to be strengthened and the thickness of the strengthening layer desired to be introduced.

The method of applying the reinforcing salt solution is not particularly limited.
It can be used in various ways such as spray coating, dipping coating and brush coating. In this case, it is preferable to remove deposits that inhibit the thermal diffusion of alkali ions in the strengthening salt solution, such as fixing of inorganic components on the surface of the glass to be strengthened, before applying the strengthening salt solution.

The surface roughness of the surface to which the reinforcing salt solution is applied is as follows:
Preferably, Ra = 0.01 μm or more. This is to minimize liquid dripping during the heat treatment of the fortifying salt solution.

[0021]

EXAMPLES (Example 1) 1, soda lime glass 2, aluminosilicate glass 3, aluminoborosilicate glass 4, borosilicate glass The reinforcement of the present invention is applied to the end faces of glass plates having different glass compositions from 1 to 4 described above. After applying a salt solution, drying and heat-treating, and introducing a reinforcing layer on the glass surface, the static pressure strength of each sample was measured using a universal testing machine. For each sample, a glass plate having a thickness of 0.8 mm cut into a size of 100 mm square was used. The fortifying salt solution is composed of 10 parts of potassium nitrate, 6 parts of sodium nitrate, and 6 parts of potassium chloride.
Parts, 4 parts of sodium chloride, 3 parts of potassium chlorate, 3 parts of sodium hypochlorite, 3 parts of thickener, and 65 parts of distilled water. The solution was applied with a brush. Glass surface roughness of coated surface is Ra
= 0.1 μm. The heat treatment temperature of each applied sample is as shown in Table 1. The strength was measured for each sample in which the reinforcing layer was introduced at the four side end faces of each plate-shaped sample. A static load was applied to the center of the plane of the sample while supporting the four sides of the sample, and the static strength before breaking was measured.

Table 1 shows the measurement results of the static strength with respect to the heat treatment temperature and time of each sample. As shown in Table 1, the static strength of each sample was increased as the heat treatment time was increased, and it was confirmed that the strength was 1.5 times that of the blank even after the treatment for 30 minutes.

As described above, according to the present invention, the strength of glass can be increased by an inexpensive and simple method, the time for strengthening the glass is short, and chemical strengthening can only be performed by a conventional batch method. However, continuous strengthening treatment became possible. For example, in a manufacturing process of a glass substrate or the like, after the polishing process, a process of applying this strengthening salt solution to the four side edges of the glass substrate using a brush or a sponge and a heat treatment process of the glass substrate after the application are provided. The process can be performed on a linked conveyor, and can be performed in a flow operation. And the breakage of the glass substrate product in the subsequent process can be reduced, and it is an epoch-making thing which can greatly improve the productivity such as the production time and the production efficiency. Inexpensively,
It can be provided in large quantities.

Claims (4)

[Claims] A glass sheet characterized by forming a chemically strengthened layer on an arbitrary part of a glass sheet product by applying a strengthening salt solution containing a thickener to an arbitrary part of the glass sheet article and heat-treating the applied solution. Product enhancement method. 2. A method for strengthening a glass sheet product, wherein a chemical strengthening layer is formed by applying a strengthening salt solution containing a thickener thereto and heat-treating the glass sheet product, particularly only on the edge end face. 3. A flat glass product reinforced by the method of claim 1. 4. A flat glass product reinforced by the method of claim 2.