JPS5913588B2 - Manufacturing method for products with glassy coating - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a method of manufacturing a product having a vitreous coating.

5. Products with a vitreous film are products made by forming a metal layer on the surface of glass, plastics, ceramics, etc. (by vapor deposition, plating, laminating, etc.) or from the metal layer surface of the glass, plastics, ceramics themselves. A glass-free film is formed on the surface of the material to improve corrosion resistance, weather resistance, hardness, acid resistance, alkali resistance, and water resistance.

Such products have been manufactured in the following manner. That is, it was manufactured by applying an aqueous alkali silicate solution to the surface of the material, drying it, and baking it to form a glassy film based on the alkali silicate on the surface of the material.In this way, The glassy coating of the obtained product has high hardness, and when subjected to sufficient heat treatment, has high water resistance, acid resistance, and alkali resistance.
However, in this glassy film, the alkali metals in the film react with carbon dioxide and sulfur dioxide gas in the atmosphere over time, become glacier-soluble components, migrate to the surface, dry, and become crystals. There was a problem that efflorescence (efflorescence) was generated due to the precipitation. '5 In order to avoid this, after forming a glassy film on the material, this is treated with nitric acid,
Alkali metals in the film are removed by immersing the film in a dilute aqueous solution such as sulfuric acid, hydrochloric acid, or phosphoric acid for a short time. In this case, in order to effectively prevent the occurrence of efflorescence10, it is necessary to increase the concentration and temperature of the aqueous solution of these acids, and to immerse the product with the glassy film therein for a relatively long time. There is a need. However, when this was done, the vitreous coating itself was dissolved in the acid aqueous solution, resulting in a problem in that the strength of the vitreous coating 5 was reduced. Furthermore, when acids are used, the working environment deteriorates due to odors and the like, and problems such as pollution arise, so a huge amount of equipment is required to deal with these problems.

This invention was made in view of these circumstances, and involves coating the surface of a material with an alkaline silicate water bath solution, drying it to form an alkali silicate film, and baking this alkali silicate film onto the material surface. A method for manufacturing a product having a vitreous film by forming a vitreous film, the method comprising:
The gist of the method is to perform a dealkalization treatment with an aqueous aluminum salt solution of a strong acid at an appropriate stage after drying the aqueous alkali silicate solution. In other words, this invention uses an aluminum salt aqueous solution of a strong acid to carry out the dealkalization treatment, instead of using an aqueous acid solution as in the conventional method. It is possible to prevent efflorescence.

A transparent glassy film can be formed on the surface of the material by dealkalization treatment using such a strong acid aluminum salt aqueous solution. A more detailed explanation of the action of the strong acid aluminum salt bath solution is as follows.

That is, the siloxane bonds that constitute the alkali silicate film are produced by the following reaction. This reaction is not 100% complete unless it is at a high temperature of about 600°C.

However, base materials with low transformation points such as aluminum cannot be fired at such high temperatures, so in the end,
The following groups remain on the surface of the film. When such a film is treated with a strong acid aluminum salt bath, groups are generated by substitution of S1 with Al.

Al has a 4-coordination with respect to oxygen, but has a 3+ charge, so the above group has a negative charge. Therefore, the surface of this film has the same number of N as the number of Al substitutions.
Therefore, a can be fixed. Even though the film has been treated with alkalization, alkali is not completely eliminated.

Therefore, when SO2 gas etc. permeate, residual alkaline content oozes out to the film surface, but in the film where Al substitution has occurred, the alkali content that is about to ooze out is fixed by the Al group, so it is not possible to Loretsense is prevented. On the other hand, dealkalization treatment using cold water or hot water or dealkalization treatment using an acid aqueous solution does not cause Al substitution, and therefore it is thought that oozing of residual alkali components cannot be prevented. Next, this invention will be explained in detail.

This invention uses an aqueous alkali silicate solution for film formation.

Examples of alkali silicates include sodium silicate, potassium silicate, lithium silicate, and the like. Among them, sodium silicate is often used. Sodium silicate is commonly called water glass and has the general formula Na2O-
It has NsiO2 and can be divided into the following depending on the number of n. n = 2 (No. 1 water glass), n = 2.5 (No. 2 water glass), n = 3 (No. 3 water glass), n = 4 (No. 4 water glass)
. In addition, lithium silicate has the general formula Li2O, nSlO
2, potassium silicate has the general formula K2O-NSlO
Has 2. Materials to which the aqueous alkali silicate solution is applied include, but are not limited to, glass, plastics, ceramics, etc., with metals deposited on their surfaces, as well as glass, plastics, and ceramics themselves. It's not a thing. An alkaline silicate water solution is applied to such materials.

The method of application does not matter. The material may be immersed in an aqueous alkali silicate solution, or an aqueous alkaline silicate bath solution may be sprayed onto the material. In this case, the concentration of the aqueous alkali silicate solution is adjusted depending on the required thickness of the vitreous film, but generally, if the concentration is 30% by weight or more (hereinafter abbreviated as 1-%), it will not be possible to immerse it. As a result, the thickness of the resulting film becomes too large, causing foaming or cracking during drying and baking, making it difficult to form a good glassy film. In order to ensure corrosion resistance, chemical resistance, etc., a thick vitreous coating is necessary (or at least one layer is required). Generally, the film thickness is approximately 5 μm or less, and preferably 0.5 to 2 μm. If such a glassy film is to be formed by one immersion, the concentration of the alkaline silicate water bath solution may be adjusted to 15% or less. It is more preferable to immerse the material one more time after drying, as this will greatly reduce the occurrence of pinholes, etc.This invention applies the alkaline silicate water bath solution to the material in this way, At an appropriate stage after drying the applied alkaline silicate permanent solution, dealkalization treatment is performed with a strong acid aluminum salt water bath.

In other words, the applied aqueous alkali silicate solution dries and the water evaporates, forming an alkali silicate film on the surface of the material (it may be partially formed), or after drying, baking is performed to form a glassy film on the surface of the material. At the stage when is formed, dealkalization treatment is performed using a strong acid aluminum salt aqueous solution. This dealkalization treatment can be carried out by spraying a strong acid aluminum salt aqueous solution onto the material on which the alkali silicate film or glassy film has been formed, or (1) spraying the material on which the above film has been formed into a strong acid aluminum salt aqueous solution. The aluminum salt aqueous solution of a strong acid used for the dealkalization treatment includes, for example, aluminum chloride, aluminum nitrate, aluminum sulfate, etc.
~30(f) Aqueous solution is used. From the viewpoint of effectiveness, it is preferable that the treatment with the aqueous solution be carried out with the temperature of the aqueous solution set within the range of room temperature to 80°C. In addition, the dry density of the aqueous alkali silicate solution applied to the surface of the material mentioned above is 150
It is preferable to carry out slowly at a temperature of about 1600C. The subsequent baking process is usually carried out at a temperature higher than the drying temperature, up to about 400°C, thereby evaporating trace amounts of water in the alkali silicate film and forming the alkali silicate film. This is the process of producing a product with a glass film by vitrifying it and baking it onto a material as a glass film. It is up to you whether you want to perform the above dealkalization treatment on the material that has been coated with the alkaline silicate water bath and dried, or on the material that has been coated, dried, and baked, but in terms of effectiveness, the former is preferred. It is more important to do this to the latter than to do it to the latter. In the product having the glassy film obtained in this way, the alkali metal that causes efflorescence is removed from the film, so that the occurrence of efflorescence over time is prevented. Next, examples will be described together with comparative examples.

[Example 1] An aluminum plate with a purity of 99.7% and a thickness of 1 inch was hub-polished, thoroughly degreased with a neutral detergent, and washed with water.

Next, pour this into water glass No. 3 (manufactured by Nihon Kagaku Kogyo Co., Ltd.).
It was immersed in a 5% aqueous solution. Next, this was dried at 90-95°C for 30 minutes, then at 130-140°C for 10 minutes, and then baked at 170-180°C for 20 minutes. This board is A
After being immersed in a 5(:f) aqueous solution (60° C.) of 1Cl3.9H2O for 2 minutes for dealkalization treatment, it was washed with water and dried at room temperature. This was used as a sample prisoner. [Comparative Examples 1 and 2] An aluminum plate treated with water glass and dried in the same manner as in Example 1 was immersed in a nitric acid aqueous solution at a temperature of 60°C and a concentration of 2001 for 2 minutes for dealkalization treatment, and subsequently treated with a nitric acid solution of a concentration of 101. ) of NaOH
After neutralization with a water bath solution, it was washed with water and dried at room temperature.

This was designated as sample (8). Further, an aluminum plate treated with water glass, dried and baked in the same manner as in Example 1 was used as a sample (C) without being subjected to dealkalization treatment. These three samples were placed in a closed box filled with saturated water vapor at room temperature, sulfur dioxide gas was pumped in so that the sulfur dioxide concentration in the box was 500%, and the samples were left in that atmosphere for one day, and then heated to 95°C. A forced efflorescence test was conducted with one cycle being one hour of standing in an oven.

The results were as follows. Sample (A): No efflorescence observed even after 5 cycles. (B): Efflorescence I after 2 cycles. (C): Significant efflorescence after 1 cycle. Furthermore, (8), (O) efflorescence was analyzed. The result is Na2s
It was O4.

Furthermore, the acid resistance and alkali resistance of these (A), (B), and (C) were all excellent. i.e. 10% hydrochloric acid,
A 10% aqueous solution of caustic soda was dropped onto the surface of the sample, the sample was covered and left for 30 minutes, then washed with water and examined for residue, but no abnormalities were found. [Example 2] After polishing the hub and degreasing with a neutral detergent, a copper plate with a thickness of 1 μm was coated with lithium silicate (manufactured by Nissan Chemical Co., Ltd., LS
It was immersed in a 15% aqueous solution of S35, Ll2O.3.5Si02).

Next, this was heated at 90 to 95°C for 30 minutes, then heated to 130°C.
After drying at ~140℃ for 10 minutes, drying at 190~200℃
Baked for 20 minutes. This board is Al(NO3)3.6H
After being immersed in a 10% aqueous solution of 20'(6'C) for 2 minutes for dealkalization treatment, it was washed with water and dried at room temperature.

This was designated as sample (D). [Comparative Examples 3, 4] Example 2
A copper plate treated with a lithium silicate water bath solution, dried and fired in the same manner as above was immersed in a 5% aqueous sulfuric acid solution at a temperature of 60° C. for 2 minutes to dealkalize it.

Next, this was washed with water and dried to form a sample (D.
A copper plate treated with lithium silicate hydrochloride, dried and fired in the same manner as in Example 1 was used as a sample (}' without dealkalization treatment).
). A forced efflorescence test similar to that in Example 1 was conducted on these samples Q)), (D, and (F')).

The results were as follows. Sample (11): No efflorescence observed until 5 cycles (8: Efflorescence after 3 cycles) (F): Efflorescence after 2 cycles In addition, acid resistance, alkali resistance, etc. were determined in the same manner as in Example 1. The results of the chemical resistance test for sample (1) L (F4), (
F') Both were beautiful.

[Example 3] A half mirror made by vapor-depositing aluminum on a glass plate was immersed in a 10% water bath solution of potassium silicate (Potassium silicate A, K2O, 3.5S102, manufactured by Nihon Kagaku Kogyo Co., Ltd.). and 30 minutes at 90-95℃, 130-14
After drying at 0℃ for 10 minutes, drying at 180-190℃ for 20 minutes.
Bake for a minute.

Add this to an 8% water bath solution (6'C) of Al2(SO4)3.
After being immersed for a minute and dealkalized, it was washed with water and dried at room temperature. This was designated as sample (G. [Comparative Examples 5 and 6]) It was treated with a potassium silicate aqueous solution in the same manner as in Example 3, dried,
The fired half mirror was dealkalized by immersing it in hydrochloric acid at a temperature of 60°C and a concentration of 50 l for 2 minutes, and then treated with 7 l of NaOH at a concentration of 1%. After neutralizing with bath solution, it was washed with water and dried at room temperature.

This was used as the sample circle. Further, a half mirror treated with an aqueous potassium silicate solution, dried, and fired in the same manner as in Example 3 was used as sample (1) without being subjected to dealkalization treatment. A forced efflorescence test similar to that in Example 1 was conducted on these samples (0, (1, (1)).

The results were as follows. Sample (C1): No efflorescence observed until 5 cycles l-0: Efflorescence I (1): Significant efflorescence after 1 cycle Chemical resistance test conducted in the same manner as in Example 1 The results for both samples (GJL (1)) were good.

Claims (1)

[Claims] 1. Glass is produced by applying an aqueous alkali silicate solution to the surface of the material and drying it to form an alkali silicate film, and then baking this alkali silicate film onto the material to form a vitreous film on the surface of the material. 1. A method for producing a product having a glassy film, the method comprising dealkalizing the product with an aqueous aluminum salt solution of a strong acid at an appropriate stage after drying the aqueous alkali silicate solution. 2. A method for manufacturing a product having a vitreous coating according to claim 1, wherein the dealkalization treatment with an aqueous solution of a strong acid aluminum salt is carried out by spraying. 3. A method for manufacturing a product having a vitreous film according to claim 1, wherein the dealkalization treatment with an aqueous solution of a strong acid aluminum salt is carried out by immersion.