DE3507375A1 - IMPROVED CLAY BRICK MATERIAL - Google Patents

Abstract

1. Tile material, in particular roof tiles, essentially consisting of conventional fired tile clays and a watertight coating, characterised in that a glass-like intermediate layer is arranged on the fired tile clay, on which intermediate layer an engobe layer is in turn arranged.

Description

BAYER AKTIENGESELLSCHAFT 5090 Leverkusen, Bayerwerk Group Administration RP Patent Department Br / Kü-c ^υ ''"* · '^ ^J

Improved clay brick material

The present invention relates to improved clay tile materials, particularly roof tiles, the have practically no water absorption capacity, which can, however, be produced in a conventional manner - with regard to firing temperatures, firing times or setting in the kiln.

Clay roof tiles are weathered after they have been laid

exposed. In very unfavorable cases, water penetrating the surface can go through the broken glass to the Get to the bottom. In any case, excessive water absorption endangers frost resistance. In bricks common relatively rough, unresponsive CaO grains can become too by reacting with water and CO2 Blast off the brick surface.

There has been no shortage of attempts to improve these clay tiles. For example, by increasing the firing temperature, it may be possible to reduce the water absorption to decrease the brick. Because of the usually very narrow sintering intervals of brick masses, this works easily to undesired deformation of the bricks during fire. 35

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In addition, an increase in the firing temperature is an often unacceptable additional cost factor.

It would also be conceivable through a fine ceramic Preparation of the brick mass increases the degree of sintering during the subsequent fire in the sense of a higher compression support financially. CaO could react and thus no longer give cause for blasting off. Such a preparation however, it is usually much too expensive and is not recommended for most brick materials self.

The present invention now relates to improved clay tile materials, in particular roof tiles, which consist essentially of conventional burnt brick clays and a waterproof coating, and the are characterized in that there is a vitreous intermediate layer on the brick clay and then another Engobe layer is located.

The invention also relates to a method for producing such materials. The water absorption of Clay roof tiles are practically prevented without the conventional firing method - in terms of temperature, Firing time and setting in the furnace - something has to be changed.

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The following substances can be used as the starting material for the clay brick material according to the invention will:

a) Brick clay with the main mineral components quartz, hat and Kaolinite and secondary particles, e.g. feldspar and Calcite. A typical composition would be about 40 * illite, 40 \ kaolinite, 20% quartz. The maximal Particle size should be less than 2 mm if possible.

b) Glass-like intermediate layer

Consisting of, for example, 85 to 95 * of an alkali-earth-alkaline aluminum borosilicate frit and 5 to 15 * clay (coefficient of thermal expansion 35 to 75. 10 " ⁷ ^ C" ¹ ).

c) engobes

Consists of 65 to 85 V of a suitable clay and 35 to 15% of an alkali-alkaline-earth-aluminoborosilicate frit. The coefficient of thermal expansion must be matched to the brick clay mass will. The same applies to the dry and Burn rate.

The brick materials according to the invention can generally be produced as follows: 30th

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Immediately after the shaping process, the molded brick is For example, a very thin layer of glaze (glass-like intermediate layer) is applied by spraying.

Then a Engobe applied, which can consist of the clays used to manufacture the brick or suitable Engobetones, each with the addition of a certain proportion of binding frits. Then the bricks fired in the usual way, being placed so close together that they are at least punctiform touch.

The baking temperatures are - depending on raw material between 900 and 1100'C, preferably 950-1050 C. ^e

The brick is solidified during the fire. The glaze layer forms with the one immediately below a thin but completely glazed intermediate layer made of the brick clay. The one about it applied engobe fulfills three tasks:

1. is because the engobe only has a small amount of melt phase developed during the fire, prevents the bricks from sticking together in the event of a fire,

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2. the external appearance of the brick is compared to that Uncoated brick is not changed, as is the case when using normal glazing processes were,

3. the engobe can be colored in almost any color.

The glazing of the brick underneath the engob layer means that water absorption is practically reduced to zero. This has two important consequences: 15

1. this guarantees frost resistance,

2. Inferior clays can also be used as raw materials for bricks can be used, provided that their sintering behavior provides sufficient solidification, dimensional stability and dimensional stability results during the fire.

The inferiority of such clays can e.g. in the practically frequently occurring contents of natural limestone inclusions exist, which are not sufficiently comminuted in the preparation of the brick mass for reasons of cost can be. These limescale inclusions are converted to CaO in the fire and can pass through when the bricks are used Hydration and fecarbonation to blast off the brick surface.

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The glaze used must meet two conditions:

1. Must be their viscosity and their wetting behavior be adjusted in relation to the brick mass so that a completely closed glazed layer can arise

2. the coefficient of thermal expansion (CTE) must be around 7. 10 ~ ⁷ 'C " ¹ lower than the CTE of the brick mass in order to reliably avoid the formation of hairline cracks.

In its drying and burning shrinkage behavior, the engobe must be limited to the shrinkage of the Brick matched. The sintering behavior must be controlled via the composition of the engobe so that a sufficient hardness is achieved without the sticking between the bricks under the practically occurring Pressure between the bricks can occur.

The subject matter of the present invention will now be explained in more detail using the following example will.

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■ 0.

example

Roof tiles made on an existing production a glass-like intermediate layer, and an engobe layer was sprayed on the top by prior heating to 60 ^# C successively. The roof tile mass contained illite, kaolinite and quartz as the main mineral components and, to a lesser extent, feldspar and calcite as secondary components.

The coefficient of thermal expansion of at 980 * C and 48

The firing time of the fired mass was 55 '10 "' * C ~. The firing shrinkage was 6 k.

The vitreous intermediate layer consisted of 90% a frit of the following composition and 10 \ slurried kaolin:

SiO ₂ 56 B ₂ ° 3 17th Al ₂ O ₃ 12th K ₂ O 4th CaO 11

The coefficient of thermal expansion of the frit was 49 '10 " ^{7 0} C" ¹ .

The engobe consisted of 75% of the clay FTRA (Fuchs'sehe Clay pit) and 25% of a frit of the following composition: 35

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SiO ₂ 56 B ₂ O ₃ 26th Al ₂ O ₃ 4th Na ₂ O 11 BaO 3

Under the above-mentioned firing conditions, the clay FTRA has a coefficient of thermal expansion of 49 · 10 ~ ⁷ 'C " ^1. The frit has a coefficient of thermal expansion of 77' 10" ⁷⁰ C " ^1. This results in arithmetic

for the engobe a coefficient of thermal expansion of 55 / which corresponds exactly to that of the brick mass. The firing shrinkage the engobe is 6 *.

The liter weight of the slip for the vitreous intermediate layer was set at 1550 g / l. the The fineness of the grind corresponded to 1 weight percent residue on the 10,000 mesh sieve. The order thickness was

3 g / 100 cm *.

The liter weight of the slip of the engobe was 1300 g / l. The fineness of the grind corresponded to 6% by weight of the residue on the 16,900 mesh screen. The order volume was

4 g / 100 cm ² . The application of the engobe immediately followed the application of the vitreous intermediate layer (wet-in-Na &application>.

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The Zeigel were in an industrial tunnel furnace at 980 * C Burned for 48 hours. The bricks were fired vertically in cassettes in accordance with the normal firing method, with the bricks touching each other point-like and flat. After this No damage to the engobe layer was visible at the points of contact.

To assess the compaction effect, uncoated and coated in the manner described Bricks determine the water absorption or water permeability in the following way:

A glass cylinder, open on both sides and having a diameter of 8 cm, was placed on the surface and sealed with a silicone ring. The cylinders were filled with water to a height of 10 cm. To the A water stain was visible on the underside of uncoated bricks after three hours. In the case of the coated brick, water loss was under the Measurement accuracy cannot be determined. On the uncoated bricks, the first lime chipping was observed in the areas exposed to water after three days. Stepped on the coated bricks no quay bursts.

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Claims (4)

Claims 1. Brick material, especially roof tiles, essentially consisting of the usual burnt brick clay and a waterproof coating, thereby characterized in that there is a vitreous intermediate layer on the fired brick clay and on it again there is an engobe layer. 2. Brick material according to claim 1, characterized shows that the coefficient of thermal expansion (CTE) the vitreous intermediate layer by 4-7 units (10 * C ~ M lower than the CTE of the brick mass is. 3. Brick material according to claim 1 or 2, characterized in that that the coefficient of thermal expansion and the drying and burning shrinkage of the engobe with correspond to the corresponding values of the brick mass . 4. A method for producing brick material according to any one of claims 1 to 3, characterized in that that a glass-like intermediate layer and then an engobe layer on the brick clay applies and after intermediate drying the material burns at temperatures between 900 and 1100'C. Le A 23 641