JPS62120496A - Production of enameled substrate - Google Patents

Abstract

PURPOSE:To prevent the occurrence of defects such as cracking when fine glaze powder is electrodeposited on a metallic core and baked to produce an enameled substrate, by dissolving a specified polymer in a liq. for electrodeposition so as to strengthen the film of the electrodeposited fine glaze powder. CONSTITUTION:When fine glaze powder is electrodeposited on a metallic core for an enameled substrate and baked to produce an enameled substrate, a liq. for electrodeposition is prepd. by adding 300-400g/l fine powder of crystallizable glaze and about 0.2-50g/l nonionic polymer having vinyl acetal groups, vinyl acetate groups or alcohol groups to an alcoholic org. solvent such as ethanol. The polymer has >=200mol.wt. and compatibility with the org. solvent. The polymer is added so as to regulate the viscosity of the liq. for electrodeposition to <=20cps. The polymer acts as cushion and adhesive in the film of the electrodeposited fine glaze powder, so the strength of the film is improved and the occurrence of defects such as cracking can be prevented.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a method for manufacturing a crawling substrate.

(Prior Art) The xi method is often used as a method for producing a floating substrate because it is easy to keep the thickness of the coating film constant and has good throwing power. Conventionally, the electrodeposition solution consists of water, glaze fine powder, a substance for imparting a charge, such as a polyacrylic acid salt, an organic substance that has a viscosity of U14, and a clay material that improves binding properties. It consisted of However, recently, in order to improve the performance of floating substrates, studies have been conducted on organic solvent-based electrodeposition and glazes that can be used for electrodeposition without containing charge-imparting substances that cause voids. I'm bored. Yes
As a glaze, it is a glaze that can solve all the problems that could be solved with conventional amorphous glazes, such as the swelling of the glaze layer at the edge of the substrate and the swirling of yuzu in the through holes. We are also developing a glaze that crystallizes during firing.

(Problems to be solved by the invention) Using an organic solvent No. 1! Even in the case of the deposition method, the L-enameled substrate is manufactured by electrocoating fine glaze powder with N and S liquids containing organic solvents, drying the entire metal core, and then firing. During the process from electrodeposition to firing, the glaze fine powder layer on the metal core is relatively fragile, and great care must be taken during manufacturing. ! Note that when the organic solvent evaporates and evaporates, the evaporated hot metal is taken away from the metal core after IILM, so the temperature of the metal core decreases and binding may occur due to the humidity in the air. In this case, there is no change in appearance before firing, but after firing, streak-like cuts (sink marks) appear in the coating film. The present invention provides a method for manufacturing an enamel substrate that solves all of the above problems.

(Means for Solving the Problems) The present invention provides a method for strengthening a coating film made of fine powder of glaze after electrodeposition, in which an organic solvent used in the electrodeposition solution is added to the electrodeposition solution. I was thrilled to discover that a method for dissolving non-ionic polymeric substances, which are commonly used in baths, is effective. The date of inclusion of fine glaze powder in the electrodeposition solution is as follows:
The amount is preferably about 500 g/l to 400 g/l, but there is no particular restriction. The organic solvent may be a single bath agent or a mixed bath agent, but from the viewpoint of ease of electrodeposition, the majority is an alcohol solvent with a carbon number of 8 or less (typical examples include ethyl alcohol, isopropyl alcohol, butyl alcohol, etc.) The thermal decomposition temperature of the polymer substance to be mixed in air is approximately 600°C at most, and more preferably 500°C or less. It is desirable that the viscosity of the polymeric material used should be 20 centivoise or less when the polymeric material is completely mixed into the organic solvent used to prepare the electromagnetic liquid.

If the mixing amount is larger than this amount, electrodeposition becomes difficult to increase γL1
It's not impossible at all, although it's possible that it might be difficult to do so. The effect of mixing polymeric substances is actually seen in C
from L2g/β, with a maximum amount of 50 g/A. If the mixture exceeds this n, there is a strong tendency for voids to occur, probably because the polymer substance is not fully gasified and released during firing during the manufacturing of the floating substrate. It becomes unusable. When using a polymer that ionizes, it is possible to perform cationic or anionic electrodeposition using the ions, but the purpose of the present invention is to perform electrodeposition using the electric charge of the enamel glaze. It is not suitable for methods that use polymeric substances to strengthen the coating film. Furthermore, if incompatible polymeric substances are used, the electrodeposited solution may not be uniform, which may be a hindrance. The present invention is particularly effective when applied to crystallized glazes. In other words, in the case of amorphous glazes, small defects after electrodeposition tend to flow during subsequent firing.
Although this is not often a problem, in the case of crystallized glazes, the defects quickly crystallize during firing and solidify without sufficiently repairing defects. Therefore, even small chips or cracks that adhere to the metal core and form in the coating film of the fine glaze powder after the flJ is applied and before firing become fatal defects.

According to the present invention, γL can completely strengthen the main body strength after electrodeposition, and all such defects can be almost completely eliminated. The polymer substances actually used have a molecular weight of 200 or more, and include vinyl acetal groups (such as vinyl formal and vinyl butyral groups), vinyl acetate groups, and alcohol groups (
For example, those containing vinyl alcohol groups, glycol, etc. are allowed. The present invention is to dissolve a polymeric substance in the electrodeposition solution, and in order to improve the properties, other substances such as clay or filler components may be added to 5j02. Z
It is convenient to mix rO2,5iZr04°Altos, etc. into the electrodeposition solution.

(Function) The coating film after electrodeposition is densely packed with glaze particles and has a certain degree of hardness, but since it maintains its strength simply by the particles catching on each other, even slight vibrations and organic solvents will not affect it. Even the influence of a slight amount of condensed water due to a drop in temperature during evaporation and transpiration can cause particles to shift, causing cracks and the like. In the present invention, by completely dissolving the polymeric substance in the electrodeposition liquid, the polymeric substance is infiltrated between the particles of the coating film after electrodeposition, and has the role of a cushioning material and an adhesive. This is intended to solve the problem of defects caused by the fragility of the steel.

(Example) Glaze component is 5iOz+ B2031Sr in oxide representation
4aQg of crystallized glaze fine powder consisting of O, MgO, and BaO, 5g of butyral resin with a medium degree of polymerization (average degree of polymerization 500 to 1QOO), and isopropyl alcohol 11 were completely mixed.
A voltage of 500 V was applied in an electrodeposition solution, and all electrodeposition was performed on an iron core with a through hole. Dry this at 120°C for 15 minutes,
After applying an impact to the exposed part of the iron core that had not been heated, the product was fired, and no defects were found in the product.

On the other hand, if butyral resin is not included in the above formulation, even if a small impact is applied to the electrodeposited coating without causing any change in appearance, the coating will form streaks after baking. The membrane was 4〈 and the internal iron core was exposed.

(Effects of the invention) In the electrodeposition of glazes using organic solvents, handling and environment during production were limited due to the brittleness of the coating film, but the present invention has been developed to improve m is sufficient even in the state of
The film is strong, and defects in the product coating due to handling or environment are largely suppressed.

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Claims (1)

[Claims] 1. A method for manufacturing an enamel substrate, which includes a step of depositing fine powder of enamel glaze on a metal core by electrodeposition and then firing, wherein the electrodeposition liquid contains an organic solvent and fine powder of enamel glaze of 0.2 to 0.2%. 50
A method for producing an enamel substrate, characterized in that it contains a nonionic polymeric substance that is compatible with the organic solvent in an amount of g/l. 2. The method for manufacturing an enamel substrate according to claim 1, wherein the majority of the organic solvent is an alcohol solvent. 3. The method for producing an enamel substrate according to claim 1 or 2, wherein the enamel glaze is a crystallized glaze. 4. The nonionic polymer substance has a vinyl acetal group,
The method for producing an enamel substrate according to claim 1, 2 or 3, which is a polymeric substance containing either a vinyl acetate group or an alcohol group and having a molecular weight of 200 or more.