DE285822C - - Google Patents

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~ JVi 285822 CLASS 48 c. GROUP

Dr. ERNST HEILMANN in GÜSTRCW i. M.

Opacifier for the production of white enamels.

Patented in the German Empire on November 24, 1911.

For the production of white opacities in enamel, tin oxide is used almost exclusively used as a mill additive. The attempts made so far, cheaper and concerning to produce equivalent substitutes for the clouding process generally have to did not lead to technically useful results.

From Tscheuschner, glass manufacture,

ίο 5th ed. 1885 ,. P. 552, and Wilkens-Schumacher, Die Keramik Tonfabrikate, 5th ed. 1884, p. 189, it can be seen that the Natronaluminat and the clay has attributed opacifying properties. This is to note that a substance that opacifies glass by no means always leads to opacity of enamels is usable. For such an opacifier one must, apart from the opacity, require that it react to a certain extent with the so-called cover enamel occurs and smooth surfaces are created.

Tests carried out have also shown that sodium aluminate, regardless of whether it is used without further ado or after annealing, enamels are added, at all there is no significant turbidity. Rather, it creates an almost transparent river.

Pure aluminum oxide behaves in much the same way when used unannealed will. With pre-annealed, pure aluminum oxide, however, it is possible to create tarnished enamels to get. However, one must then use such large amounts of aluminum oxide that a rough one and thus for the enamel technique completely unusable surface is created. · This is due to the fact that annealed Aluminum oxide does not dissolve in the glass flux to the extent that the requirement for that The formation of a well-clouded enamel with a smooth surface is given.

Magnesium oxide, which is also pure white, has never been used as an opacifier for Email has been suggested, and attempts made in this direction have also yielded a negative result.

The surprising result has now been found that mixtures of magnesium · And aluminum oxide or zinc oxide Aluminum oxide, i.e. from substances that are not used on their own as opacifiers for enamels can be, give good clouding effects when they have been heated so high that it leads to the formation of spinels or if there is an excess of one of the mixture components Formation of solid solutions of the spinels with magnesium oxide or aluminum oxide occurs.

In Wilkens-Schumacher, Die keramischen Tonfabrikate 1884, p. 174, spine rope-like bodies (R ₂ O ₃ RO), such as alumina cobalt oxide, alumina zinc oxide cobalt oxide, etc., are listed, which are to be used as stains for the production of colored glazes. However, it cannot be concluded from this that annealed mixtures of aluminum oxide with magnesium oxide or aluminum oxide with zinc oxide are suitable as opacifiers for white enamels. Whitening agents for iron enamel are also added as a mill additive to the cover enamel and essentially only work through fine mechanical

Claims (2)

mechanical distribution in the glass flow (cf. J. Grünwaid, Theory and Practice of the Sheet Metal and Cast Enamel Industry, p. 87). The clouding effect of the annealed mixtures in enamels is increased if tin oxide, zirconium oxide, titanic acid, silicic acid or other white-colored, fire-resistant materials or corresponding mixtures of the substances mentioned are added to the mixtures of aluminum oxide and magnesium oxide or aluminum oxide and zinc oxide and the mixture is annealed. Additions of 10 percent are sufficient, calculated on the mixture of aluminum and magnesium oxide or aluminum oxide and zinc oxide, i.e. H. if 5 percent of the opacifier is used on the enamel mass, 1/2 percent is broken down in order to achieve considerably stronger opacity effects compared to the pure, annealed mixtures. The plus in effect is greater than it is. can act as a purely additive effect. It remains to be seen whether the additives only increase the opacity or also improve the capacity of the opacifier in the enamel. These iron properties of annealed mixtures of aluminum and magnesium oxide or aluminum oxide and zinc oxide, regardless of whether they are used pure or with the additives mentioned, by no means, otherwise they would already have a technical use in the multiple attempts to create a substitute for tin oxide found. The unexpected effect is also evident from the fact that z. B. calcium spinel and barium spinel, which are also white-colored compounds, are completely useless for clouding purposes; namely, they completely decompose when they are melted down with the cover enamel. In contrast to this, zinc spinel has proven to be a good opacifier, but due to its toxicity it should only be used for so-called cosmetic enamel. The new invention has made important economic progress. This is obvious when one considers that the annealed mixtures can be produced much cheaper than tin oxide, which was previously used on a larger scale for enamel alone. The savings compared to tin oxide are still considerable when the above-mentioned additives are used to improve the clouding effect. . Ρ.Λ T E N T - A N S P R Ü C H E: " 1. Opacifier for the production of white enamels, characterized in that es' from mixtures of magnesium and aluminum oxide or zinc and aluminum oxide exists that have been heated so high that it leads to the formation of .Spinelles or if there is an excess of one of the mixture components to form solid solutions of the spinels with magnesium oxide or aluminum oxide comes. 2. opacifier according to claim 1, characterized in that it is next to the Spinels or the solid solutions white-colored refractory materials such as Contains silica, tin oxide, zirconium oxide or titanic acid.