CS241106B2 - Method of ceramic objects' surface quality treatment and increase of its breaking resistance - Google Patents

Abstract

1. Process for improving the surface finish and the fracture behaviour of ceramic articles, wherein an unfinished article is first furnished with a primer, then preheated and electrostatically coated with a plastics powder which forms a lacquer film at raised temperature, characterized in that the unfinished article is cleaned with a silane wash, then preheated to approximately 160 degrees C with drying of the remaining silane, then the plastics powder is applied onto the silane as bond-promoting agent, is heated to approximately 190 degrees C and, after cooling, is coated with a transparent organic wet lacquer by dipping or spraying.

Description

BACKGROUND OF THE INVENTION The present invention relates to a method of adjusting the surface quality of a ceramic article and enhancing it.

resistance to breakage of, for example, flower pots, flower bowls and vases, jugs, art products, dishes, heater linings and building materials such as roofing tiles, wall and floor paneling tiles, as well as pipes.

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Ceramic products of the aforesaid types are delivered for use without firing without any surface treatment; therefore, due to their porosity, they have a rough surface and are more or less permeable to liquids and gases depending on their pore volume.

This leads, for example, to relatively large evaporations in pots and, over time, to the formation of efflorescence, which over time makes the pot unsightly.

It is known to provide ceramic articles with glaze. This happens during the preliminary firing at ^t e ^pl of ^thee Mezice ^{H 900 F 950 °} C and ^P oc ^hl Assigning it en ^{d of d} of m ^p vcxlné sus ^to Enns eramic ^to a mixture ^of a. p and ^s are firing temperature within obv ^{Y 2,} E 1 00 and ¹ 500 ° C.

This creates a hard or colored coating that lends the object not only an attractive appearance, but also impermeability to gases and liquids. Burning, however, is very costly due to the time it takes between 1 and 3 days, and because of the high firing temperature.

A further disadvantage of traditional clay or ceramic products with or without glaze is their relatively low resistance to breakage and the tendency to form sharp-edged fracture surfaces.

In addition, the rough surface of the glazed ceramic articles creates a considerable risk of environmental contamination and the resulting need for care, but this is to some extent limited by the fact that the cleaning agents easily settle in the pores of the product or possibly even enter the interior of the container and cause damage.

Finally, the risk of shattering is not negligible, as conventional clay or ceramic products are extremely fragile.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for adjusting the surface quality of ceramic articles, which would improve it and provide greater resistance to breakage.

The object of the invention was solved by first applying a silane liquor to the preform,^pot^E se^at te^plO^you 1⁶⁰ Noc: 2 ° C^polotovar^exE^dE^hscreams and dries,^gavee se o^pand^three st^{he says}him ele^ktrosta tactically charged layer of plastic powder based on epoxy, polyester, polyurethane, acrylate,^eventand^dpolyvini^lC^hof chloride of up to 70^of se^at temperatures up to²⁰⁰ ° C layer^pr^ášku melt or cure.

Further, according to the invention, the plastic powders are applied to the blank individually or several types simultaneously or in succession, optionally as a mixture of powders.

According to the invention, a two-component plastic powder is also applied to the blank.

Finally, according to the invention, a coating layer of an organic lacquer, in particular a colored lacquer, is applied to the workpiece with the molten or cured plastic layer applied by dipping or spraying.

The plastic coating applied by the method according to the invention increases the resistance of the ceramic article to breakage, increases the surface quality of the ceramic product and prevents efflorescence due to its high density. In addition, it provides a smooth, easy-to-care surface which is hygienic and extremely pleasant to the touch, so that the coated containers are also suitable as drinking containers.

In addition, due to the pore filling of the ceramic article with a coating, low evaporation losses are possible, which allow potting watering in pots more efficiently. In addition, in the case of closed bottom containers, the trays may be omitted, otherwise necessary to prevent moisture damage to the surrounding objects.

In the following, the method according to the invention is described in detail in relation to the attached drawing indicating a conventional pot.

The starting material is a known clay-fired pot 7, which is put into rotation and sprayed first with 3% silane lye to clean the surface and simultaneously apply silane as a substrate.

The preform is then preheated to 160 ° C and dried. The silane coating formed after drying serves to mediate adhesion of coating 2 - then electrostatically deposited.

The preheated preform, pot 1, is then re-rotated, sprayed with a conventional spray gun for 10 seconds with powdered particles whose electrostatic charge is between 30 and 40 kW and whose size is below 100 yum to form a layer of approx. thickness 60 to 70 дип.

In this case, the starting blank can be partially covered by a template according to the desired boundary of the areas to which the coating is not to be applied.

After coating 2 is applied, the blank is made through a tunnel furnace where the coating 2 is cured at a temperature of about 190 ° C. Thereafter, the preformed pot 1, which is coated with a coating 22, is cooled slowly to room temperature and dipped in a glazing organic varnish, provided with a coating layer 3.

In a long-term experiment several pots 7 coated with an epoxy or polyester resin coating 2 were observed. An extremely high resistance to atmospheric influences was found.

Furthermore, the coating 2 proved to be insensitive to water, plants and water for watering. In a long-term experiment, adhesion was examined by a 72 hour test to detect sweating at 45 ° C and 100% humidity, as well as a grid test at a grid line distance of 2.5 mm. In both tests, an extremely high adhesion was found, especially also at the intersections of the cutting lines.

At the same time, compared to pots 7 of the same type but not coated 2, a considerably lower consumption of potting water and a pot-free surface of pots without any effect on plant growth was found.

Claims (4)

SUBJECT OF THE INVENTION Method for adjusting the surface quality of ceramic articles and increasing their resistance to breakage, characterized in that a silane lye is first applied to the semi-finished product, then the semi-finished product is preheated and dried at 160 ° C, further sprayed with an electrostatically charged plastic powder coating. an epoxy, polyester, polyurethane, acrylate or polyvinyl chloride base with a thickness of up to 70 ° C, whereupon the plastic powder layer melts or cures at a temperature of up to 200 ° C. 2. Method according to claim 1, characterized in that the plastic powders are applied to the workpiece individually or several types simultaneously or in succession, optionally as a mixture of powders. 3. Method according to claim 1 or 2, characterized in that two-component plastic powder is applied to the semi-finished product. Method according to one of Claims 1 to 3, characterized in that a semi-finished product with a molten or cured plastic layer applied by dipping or spraying is applied to the coating layer of an organic lacquer, in particular colored paint.