DD231060B1 - ADDITIONAL ADDITIVE TO GLASS ACIDS AND METHOD FOR THE PRODUCTION OF COLOR GLASSES - Google Patents

Description

Explanation of the essence of the invention

The object of the invention is to provide a coloring additive for glazes, which is a complex color oxide with silicate admixtures, the rate of dissolution in the glaze melt is relatively low due to its crystallinity, which is compatible with other color bodies, inexpensive to manufacture and in its preferred embodiment of a Secondary raw material with an advantageous particle size distribution exists.

Another object of the present invention was to provide a process for producing colored glazes with this coloring additive, which makes it possible to decorate colored clay-ceramic body pieces with high quality.

In accordance with the object, a coloring additive for ceramic glazes and a method for producing colored glazes were found. The characteristics of the additive and of the method can be found in the claim of the invention.

The coloring additive of the invention is partially crystalline and consists of an intimate mixture of

40-95% crystalline heavy metal oxides and

5-60% X-ray amorphous, predominantly glassy solidified schla cke similar material.

Small proportions of other crystalline phases are possible. The chemical composition is within the following limits: 35-65% Fe ₂ O ₃ ; 5-15% MnO; 0.5-2.5% Cr ₂ O ₃ ; 0-0.5% P ₂ O ₅ ; each 4-12% SiO ₂ ; Al ₂ O ₃ ; MgO; CaO.

An advantageous embodiment of the additive according to the invention is the electrostatic precipitator in electrical steel foundries with a sufficient proportion of high-quality steels in the production range. It has surprisingly been found that the additive according to the invention, due to its composition, the bonding of its main components and its particle size distribution without any kind of pretreatment or treatment can be added directly to the mill offset, causes reproducible discoloration of the glaze and can be used over a wider temperature range. The method consists in the direct addition of the additive according to the invention to the mill, in which the glaze slip is prepared as a raw or frit glaze. The addition may take place at the beginning or shortly before the end of the grinding.

The additive according to the invention is virtually inert to the grinding media (H ₂ O and adjusting agent). It causes no flocculation or other segregation in the slip. In special cases, can be dispensed with the per se known adjusting means in the Glazeschlickerbereitung, since the additive according to the invention acts as an actuating agent due to its calcium silicate content. This was observed especially in the preferred embodiment of the additive according to the invention.

The investigations carried out have shown that the inventive agent in connection with the inventive method is applicable in all Glasurversätzen that those skilled for glazing tonkeramischer shards at 1000-1300 ⁰ C known. It was found that the composition of the invention with addition of up to 10%, which is absolutely sufficient for intensive color development, depending on the glaze composition, firing time and firing temperature, the thermal expansion behavior and their Ausmelzverhalten practically not changed. Due to the material-related combination of the coloring heavy metals (iw iron, manganese and chrome), the color palette to be developed is limited to the shades yellowish-beige to deep brown. Other effects, eg. 8. a decorative mottling, can be achieved if the dissolution rate of the composition according to the invention in the glaze is adjusted by varying the grinding conditions. For this purpose, the expert requires only a few experiments. Advantageous glaze compositions are in the following ranges (in% by mass):

1000-1100 ⁰ C

55-65

7.5-10.5

2-5

2-5 2.5-5 2.5-5 <0.2

2-4

4-10

9-13

The addition according to the invention in its advantageous embodiment as electrostatic precipitator dust has a particle size distribution of 96% less than 0.063 mm.

Preferably 1 150-1 300 Ausschmelztemperatur 58-65 SiO ₂ 8-12 Al ₂ O ₃ 1-5 MgO 7-12 CaO 1.5-3.5 Na ₂ O 2-5 K ₂ O <0.2 Fe ₂ O ₃ 0.1-1.0 TiO ₂ 2-9 BaO 0-6 ZrO ₂ 0-5 ZnO - B ₂ O ₃

embodiments

The invention is further illustrated by the following embodiments, wherein it is not limited to these. starting materials

1. Coloring additive: intimate mixture of 40-95% crystalline heavy metal oxides and 5-60% glassy solidified slag-like material of the following composition (in% by mass):

56Fe ₂ O ₃ ; 11 MnO; 1.5 Cr ₂ O ₃ ; 0.1 P ₂ O ₅ ; each between 7 and 8 SiO ₂ ; Al ₂ O ₃ , CaO, MgO

2. Tonkeramische shards

Mass 1 of different clays, kaolins, feldspar and quartz, mass 2 of different clays, kaolins, calcite and quartz are prepared in a known manner, molded and dried, mass 2 at 1 100 ⁰ C preheated for 1 h.

3. Glaze slip of feldspar, barium carbonate, kaolin, quartz, calcite, zirconium silicate, talc (Example 1 + 2) and commercial glaze frit quartz, kaolin, zinc oxide (Example 3) of the following composition (in% by mass);

ZrO ₂ - 4.91 -

From the components mentioned are prepared in known and usually glazes of the specified compositions and added based on the dry mass of the glaze:

Example 1 5% of the coloring additive about 10 minutes before completion of the milling process

Example 2 5% coloring additive, 4.6% Fe ₂ O ₃ and dried manganese-containing sludge corresponding to 1.8% MnO ₂ at the beginning of the grinding process

Example 3 5% of the coloring additive at the beginning of the grinding process

This prepared glazes are applied to the dried cullet of mass 1 (Example 1 + 2) or the culled cullet of mass 2 (Example 3) and burned at 1 25O ⁰ C or 1 050 ° C.

Example 1 gives a silky matt glaze with dark specks, in example 2 and 3 shiny brown glazes.

example 1 Example 2 Example 3 62.5 59.4 59.5 9.94 11.61 8.95 4.53 1.09 2.49 8.99 10.40 2.52 2.18 2.39 3.73 3.30 3.47 3.73 0.15 - - 0.47 0.03 - 7.94 3.40 3.32 - 3.30 4.97 10.79

Claims (4)

Invention claim: 1. Coloring additive for glazes, characterized in that it consists of an intimate mixture of Spinel phases, predominantly magnetite (Fe ₃ O ₄ ) and - X-ray amorphous substance the chemical composition (in% by mass) 35-65 Fe ₂ O ₃ OO ₂ P ₂ O ₅ 5-15MnOJeWeMs-I- ^ SiO ₂ , Al ₂ O ₃ , MgO 0.5-2.5Cr ₂ O ₃ consists with a grain size distribution of at least 90% smaller 0.063mm. 2. Coloring additive according to item 1, characterized in that it is an electrostatic precipitator of the production of electrical steel foundries. 3. A process for the preparation of colored and decorative glazes, characterized in that the coloring additive in proportions of 1 to 20Ma .-% (based on the dry matter) directly to the mill. the glaze slip treatment is added and the glaze slip is then applied to clay-ceramic, possibly bruised shards and burned at 1 000 to 1 300 ° C. 4. The method according to item 3, characterized in that the glaze slip additionally up to 10% Fe ₂ O ₃ or MnO ₂ , the latter are preferably added in the form of a resulting in the production of potassium permanganate manganese sludge. Field of application of the invention: The invention relates to a coloring additive for glazes and a method for producing colored glazes for preferably clay-ceramic products. Characteristic of the known technical solutions For a number of ceramic products, the application of a glaze is known to be indispensable for the formation of the desired performance properties. It is prepared by grinding the glaze offset with water and optionally adjusting agents to a suspension and applied as such. If the glaze offset contains water-soluble or toxic components, these are fused with SiO ₂ and converted into a glassy granulate, the frit. This is then ground to Glazeschlicker after addition of the remaining glaze components. Raw and frit glazes are basically transparent, i. their decorative effect is determined by the shards. If, for aesthetic reasons, a colored and / or cloudy glaze is desired, appropriate additives must be added to the glaze slip. In general, these are synthetic or processed natural raw or secondary raw materials. Their essential deficiency (annealing, fine grinding, washing) can be seen in the necessary treatment (SINGER, F. & SINGER, S.S .: Industrial ceramics, Springer-Verlag Berlin u.a. 1969). For coloring and clouding of glazes, experience has shown that pigments, which are virtually insoluble compounds in the glaze flow, or color oxides, are used. The color oxides usually dissolve in the glaze. The number of colors and shades that can be achieved is practically unlimited, and the number of suitable recipes is immense. Glaze offsets are known in which part of the costly glaze raw materials is replaced by cheaper products. For this one uses u.a .: - Different rocks, such. B. Basalt (BALDUIN, H., GRÖSSL, K .: Sprechsaal 108/1975/9, pp. 503-506), Perl it (SU patent 464 544), Liparit (SU patent 547 405), granodiorite (DD-WP 206139) - various ores (SU patent 408921, 355.111) - various slags (DD-WP 157327) - flux-rich clays - Products of the binder industry (DE-OS 2701 064). Due to the almost always given levels of coloring elements in these and similar substances, a more or less specific coloring of the glazes is achieved in addition to the replacement of frit or glaze raw materials with flux effect at the same time. Of course, the substances mentioned and the processes based on their use for the production or coloring of glazes adhere to certain disadvantages that are contrary to a broad application (uneven composition, harmful admixtures, additional processing effort). Object of the invention The aim of the invention is to provide a coloring substance for glazes and to find a process for the production of colored glazes on clay ceramic shards.