DE2057643A1 - Process for the production of a hollow glass block with an enamel coating - Google Patents

Description

VE 159

Applicant: Compagnie de Saint-Gobain-Pont-a-Mousson 62, Boulevard Victor Hugo
92 - Neuilly-sur-Seine / France

Process for the production of a hollow glass block with an enamel coating

The invention relates to a method for producing a hollow glass block with a burned-in glaze or enamel coating on at least one outer visible surface, in which the glaze or enamel powder is applied to the cold glass surface and baked at a temperature above the upper transformation point of the glass.

To cover glass blocks with a glaze or enamel, is known per se. However, enamels or glazes are used with stoving temperatures below the above Transformation point of the glass. Such low melting points However, enamels or glazes are not resistant against atmospheric influences. · so that they are attacked by them and become unsightly in the long run. You will therefore in Hegel only used for coatings on the inside of the glass blocks.

10982471151

BATH ORIGINAL

VE 159 - 2 -

Resistant enamels or glazes, on the other hand, have a higher melting point. They require baking temperatures that are above the upper transformation point of the glass and around the dilatometric softening point of conventional glasses. Their stoving temperature is given as at least 57O ⁰ C, for example.

At the high levels required for such resistant enamels At baking temperatures, the glass is softened to such an extent that the risk of deformation is extremely high. Schor at low stress it begins to give way and loses its shape. This risk of deformation is particularly great with one Hollow body closed on all sides, like a hollow glass block because the air trapped inside expands when heated, creating a considerable internal pressure leads. The walls give in to this overpressure and are deformed, making the glass blocks unsaleable.

The invention has for its object to avoid the difficulties referred to, and a method producing Zuin before. To create hollow glass blocks with a coating of high-melting enamel, through which undesired deformation of the stone is avoided.

The method according to the invention consists in that in the case of high-melting enamels with above the upper Tranofozmationspunktes the enamel powder is applied to the finished cold glass block, and the cold glass brick with the enamel powder without previous preheating superficially heated to the stoving temperature and only briefly at this temperature ο Time is kept that although the outer layers of the glass block take the baking temperature, the inner layers

_ 3 _
109824/1151

BATH ORIGINAL

PU 139 _ 3 _

but still, remain sufficiently rigid to allow for any deformation to avoid the overpressure arising inside the glass block.

It has been shown, for example, that with a commercially available hollow glass block these 'conditions are met if the glass blocks provided with the enamel powder coating are placed directly in an oven with a temperature of 57O ⁰ C without preheating and are kept in this oven for a maximum of 15 minutes.

In a further development of the invention, the glass block is very quickly to a temperature of about after the burn-in process Cooled 20 ° below the upper transition point, whereupon the further cooling takes place at the normal, very low cooling rate.

With the aid of the method according to the invention, glass blocks can be produced with any enamel application. E.g. continuous transparent enamel layers for the production of colored ones Glass blocks or non-transparent, i.e. opaque, enamel. be applied. One-color or melir-colored figurative representations can of course also be lifted from continuous layers raise.

The new method is to be explained in more detail using an example will:

A 19 x 19 x 8 large one, welded together from two pressed half stones Hollow glass block with an average wall thickness of? mm becomes with a Email order in the form of a picture. The job itself can be done by any method, for example also according to the known decal process.

- 4 1 09824/1151

BATH ORIGINAL

VE 159

The enamel powder requires a stoving temperature of the least
at

at least 57O ⁰ G. The upper transformation point of the glass lies

After the enamel powder has been applied, the cold glass block is placed in an oven with a temperature of 58O ° C. without any preheating and left in this oven for 10 hours. During this time the surface layers of the glass block have reached a temperature of 570 ° C, and the enamel powder melts and is burned into the glass surface. There is a strong temperature gradient within the walls of the glass block, and after this time there is still a sufficient temperature gradient to give low temperature below 54O ⁰ C on to the already softened outer layers despite the building up excess pressure in the interior of the stone sufficient support. After 10 Hinuten the glass blocks are removed from the oven, cooled by briefly holding in air very quickly to about 520 ⁰ C; and then placed in a cooling furnace, in which it has been slowly cooled to room temperature in a known manner within about 5 hours in order to avoid any build-up of tension during the cooling process; to avoid.

BATH ORIGINAL

109824/1151

Claims (2)

VE 139 - 5 - Godfather to spray before fiJ Process for the production of a hollow glass block with sinen: Burned-in glaze or enamel coating on at least one outer visible surface, in which the glaze or enamel powder is applied to the cold glass surface and at a temperature above the upper transformation point of the glass is baked in, characterized in that when using high-melting erna ils with above the upper transformation point of the glass enamel powder is applied to the finished, cold glass block, and that with the enamel powder provided cold glass blocks without prior preheating superficially on the egg burn temperature heated and only hooded at this temperature for such a short time It becomes clear that the outer layers of the glass structure do not take on the stoving temperature, but the inner layers still do Remain sufficiently rigid to prevent the stone from deforming due to the overpressure created inside the glass block to avoid. 2. The method according to claim 1, characterized. That the glass building leg very quickly up to after the burn-in process a temperature of about 20 ° below the upper transfer peak is cooled, whereupon the further AbIdUvI-UiIt-; Follows with normal slow cooling speed.