KR19980042869A - Pigment for making purple ceramic ornaments, preparation method thereof and use thereof - Google Patents

Abstract

The coating is applied by coprecipitation of oxide hydrates of one or more elements from a range of stobable support materials, in particular Al, Si, Sn, Pb, Ti, Nb, Ta, Sc, Y, La, Ce and Zn. Purple pigments according to the invention based on glass frits and water insoluble gold compounds or colloidal gold are distinguished from pigments of the prior art of similar composition by improving color stability upon high temperature firing. The pigment is obtainable by coprecipitation of an oxide hydrate and a gold compound or colloidal gold in the presence of a support material in the presence of a reducing material in the aqueous phase. Pigments containing gold compounds become purple upon heat treatment or by chemical reduction. Preferred pigments containing gold compounds, which can be used directly as decorative colorants, conveniently enhance coloration during firing of ornaments.

Description

Pigments for making purple ceramic ornaments, preparation methods thereof and uses thereof

The present invention relates to pigments for the production of purple ceramic ornaments, methods for their preparation and their use. The pigments are based on stobable support materials, in particular glass fluxes, oxide hydrates and gold compounds or colloidal gold. Colorless or colored pigments according to the invention, which can be used directly as decorative colorants, exhibit a stable glossy purple even at elevated temperatures upon firing.

Purple pigments based on ceramic materials and colloidal gold can be obtained by various methods, and have been used for a long time as producing ceramic ornaments, coloring plastics and as lacquers, cosmetics, glass colorants and decorative colorants.

Until recently, the method for preparing purple pigments was characterized by precipitating purple Cassius gold in gel form (colloidal gold adsorbed on tin oxide (IV) hydrate) from an aqueous gold salt solution using tin (II) salts, Mixing purple wet gold with finely divided glass, presintering the mixture at 600 to 800 ° C., where the gold particles are incorporated into at least some glass, and finely grinding the sintered material And, if necessary, several process steps of step (d) of adding a silver compound and / or other flux to give the desired color tone. A significant disadvantage of this process is that it is very difficult to separate the purple gold in gel form from the aqueous solution of precursor (a) and the color tone of the final pigment is affected by poor regeneration by aging the purple gold (e.g. browning on partial drying). In addition, a crushing step and an energy intensive sintering step that reduce space / time yield are also required. It has also been found that pigments prepared in this manner are not sufficiently stable in color at relatively high firing temperatures (about 1200 ° C.). That is, they become blurred under these firing conditions.

There have been many attempts to improve the methods mentioned above:

Coprecipitates of colloidal gold and oxide hydrates that are more easily filterable can be obtained by coprecipitation of purple gold in the presence of oxide hydrate forming materials such as Al and Sn salts, where the hue of the coprecipitates is more readily reproducible. At the same time it is more resistant to aging (Romanian Patent No. 64442B (Chemical Abstract 98 (26): 22 07 40e)). However, the remaining process steps for producing purple pigments correspond to the above-mentioned steps (b), (c) and (d), so the whole process still requires considerable effort. According to DD-PS No. 143 423, purple gold can also be precipitated in the presence of an inert material, for example kaolin, feldspar or pegmatite. The wet precipitate is then mixed homogeneously with the glass flux to adjust the color tone and further silver carbonate is added, wet milling and sintering at 650 to 680 ° C. and then milling again. This method also relates to the above mentioned disadvantages, in particular inadequate color stability at relatively high firing temperatures.

Pearlescent purple pigments based on thinner particles coated with metal oxides, in particular Mica coated with TiO ₂ , on which the tin oxide outer layer is coated with colloidal gold are known in the literature. DE-OS 37 31 174]. Here, the film containing gold is always placed on the metal oxide layer which must first be applied on the thin film support. The metal oxide or metal oxide hydrate layer, in particular the TiO ₂ or titanium dioxide hydrate layer, first hydrolyzes the metal salt to precipitate it in a thin film material, in particular mica particles, and then the tin salt or tin dioxide hydrate and gold in colloidal form with gold salts. The tin (IV) salt is hydrolyzed and precipitated simultaneously in the presence of a reducing agent, in particular tin (II) salt. After precipitation, it is calcined at 700 to 1100 ° C. The preparation of such pigments is quite complicated and expensive.

DE-OS 41 06 520 describes glass frits with an average particle diameter of 0.5 to 50 μm, coatings containing 0.05 to 5% by weight of colloidal gold and purple pigments based on any tint modifying metal. In the presence of free frit, a reducing agent such as glucose is used to reduce the water soluble gold compound in the aqueous suspension to provide a coating. The resulting pigments show unsatisfactory color stability during firing at high temperatures. That is, they blur as the firing temperature rises.

According to DE-OS 44 11 104, purple pigments can mix and / or grind the support material with the gold compound in anhydrous form, or contact a solution or suspension of the gold compound with the support material, wherein a soluble gold compound such as ammonia And a precipitant may be present, followed by heat treatment below the decomposition temperature of the gold compound and below the sintering temperature of the support material, where the gold compound is converted to colloidal gold. According to DE-OS 44 11 103, purple ornaments can also be made using pigment precursors prepared as above but can be made using pigment precursors which have not been heat treated and are therefore almost colorless. In the pigments or pigment precursors described in the following references, the chromogenic metal colloids or precious metal compounds each cover the surface of the material without further oxide hydrates. At a stoving temperature of 1000 ° C. or higher, such pigments or pigment precursors exhibit inadequate color brightness and the color depth decreases as the stoving temperature rises.

U. S. Patent 4,839, 327 describes products containing gold, consisting of finely divided materials such as metal oxides or mixed oxides, which are suitable as catalysts and have ultrafine gold particles having a particle diameter of less than 500 nm located thereon. The process involves first depositing gold hydroxide from a water soluble gold compound on a substrate in an aqueous phase and then converting the gold hydroxide to colloidal gold by treatment with a reducing agent or by heat treatment. In this document neither the color of the product is mentioned nor its use as a pigment. The thermal stability of the product obtained using this method does not correspond to the high temperature stoving, ie the thermal stability required at 1100 to 1300 ° C.

Finally, pigments based on colloidal gold and glaze stable compounds such as ZrSiO ₄ , SnO ₂ or Al ₂ O ₃ are known from British Patent 1 436 060. It is prepared through a solid state reaction. This pigment does not contain oxide hydrate, and the color is poor in brightness and poor in appearance.

It is an object of the present invention to provide a pigment for producing a purple ceramic ornament with improved high temperature stability, wherein the color of the stowed ornament is due to colloidal gold. The pigments should be able to be used for stoving at high temperatures, ie above 1000 ° C., in particular from 1100 to about 1300 ° C., and using prior art pigments based on purple Cassius gold precipitated in the presence of a support material at a given gold content in the pigment. Darker colored ornaments should be obtained. Another object is to provide a suitable method for preparing such pigments.

This object is achieved by substantially stoving materials, in particular one or more finely divided support materials (a) from glass frit, Al, Si, Sn, Pb, Ti, Zr, Nb, Ta, Sc, Y, La, Ce and Zn A support consisting of at least one oxide hydrate (b) of at least one element from a range comprising and at least one water insoluble gold (II) or gold (I) compound or colloidal gold (c) (wherein calculated as oxide The material and the oxide hydrate are present in a weight ratio of 10 to 0.1 and the gold content of the pigment is 0.05 to 10% by weight), one or two in the absence of a reducing agent for gold compounds in the presence of a support material in an aqueous or aqueous-organic phase. Co-precipitating the above oxide hydrate with a water insoluble gold compound or colloidal gold (where a solution containing at least one soluble gold compound or colloidal gold, the solubility of the metal present in the oxide hydrate One or more combinations and one or more precipitants are used), when the water-insoluble gold compound present in the co-precipitate is converted to colloidal gold, which is reduced by co-precipitation using a conventional reducing agent or by pyrolysis at 100 to 300 ° C. Achieved by a pigment suitable for producing a purple ceramic ornament on high temperature firing, obtainable by a method of

Pigments according to the invention which contain a gold compound in the coprecipitate are usually almost colorless, but the coprecipit is brown when coprecipitated with a water-soluble sulfide. Almost colorless or brown pigments containing one or more gold compounds are hereinafter referred to as unreduced pigments. Almost colorless indicates that the unreduced pigments in fact exhibit a color derived from the support material, the oxide hydrate and the precipitated gold compound, but do not exhibit the purple color obtained by thermal decomposition of the gold compound or only by a chemical reduction step during firing of the ornament. Means that. These unreduced pigments are typically white, light yellow or gray or may be brown as mentioned above. The unreduced pigments according to the invention, based on the coprecipitation of oxide hydrates and gold compounds prepared in the presence of a support material, are not only the simplest for their preparation but also use colloidal gold solutions at high temperatures for a given gold content. Particularly preferred is to obtain a purple colored ornament which is darker than the pigment according to the invention, which is already purple because the coprecipitate containing the gold compound is reduced and then coprecipitated. Why the unreduced pigments according to the invention, i.e. pigments containing gold compounds, have better thermal stability than the pigments according to the invention containing colloidal gold, i.e. why the ornaments have a darker color upon high temperature firing It is not clear yet. Surprisingly, both types according to the invention are much more thermally stable than pigments of the prior art having similar compositions and identical gold content. The pigments of the prior art have low thermal stability and are practically withheld during high temperature firing of ornaments.

The pigments according to the invention consist essentially of at least one finely divided support material, at least one oxide hydrate and at least one water insoluble gold compound or colloidal gold. The term substantially includes a total amount of other compounds, such as one or more color tone enhancing metal compounds, of the elements from the range the pigments include Ag, Cu, Co, Ni, Ru, Rh, Pd, Os, Ir and Pt compounds. It may further contain up to about 10% by weight or less. In addition, small but effective amounts of organic pigments may be present as substantially colorless pigments. Pigments colored in this way have the advantage that the prints thus produced are readily visible before firing. Finally, conventional pigment aids such as flow aids may also be present.

Storing material during firing of ornaments such as finely divided glass frits, natural and synthetic silicates such as aluminosilicates, together with mixed oxides and metal oxides such as SiO ₂ , ZrO ₂ , SnO ₂ , TiO ₂ and colorless blueite It is used as a support material for pigments. Particularly preferred support material is finely divided glass frit. Glass frits of various different chemical compositions are known; The composition determines the properties of the glass frit, in particular the melt behavior and coefficient of expansion, which are critical for application. When producing purple pigments stowed at elevated temperatures, ie at temperatures above 1000 ° C., in particular from 1100 to about 1300 ° C., those skilled in the art soften at the intended firing temperatures and have a beneficial effect on promoting coloration. Mitch will choose a glass frit. The average particle diameter is typically 1-10 μm and 90% of the particles should preferably be less than 20 μm. From a variety of commercially available glass frits one can choose a glass frit that best fits the support to be decorated on which the pigments according to the invention will be based; Thus, defects such as flaws, cracks, pinholes and blurs in the ceramic ornament can be prevented.

The term oxide hydrate is a gel as obtained by precipitation of soluble compounds of Al, Si, Sn, Pb, Ti, Zr, Nb, Ta, Sc, Y, La, Ce and Zn from the aqueous solution in the form of oxides and / or hydroxides. Means a precipitate in the form. In soluble compounds and oxide hydrates, Si, Sn, Ti, Zr and Ce are tetravalent, Nb and Ta are tetravalent, and Al, Sc, Y, La and optional Ce are trivalent. The term oxide hydrate includes an oxide forming gel and when thermally treated according to the invention at 100 to 300 ° C. to decompose the gold compound, it also comprises a precipitate obtained by drying the precipitate at ordinary conditions, generally below 100 ° C. do.

Preferred oxide hydrates formed during coprecipitation are aluminum, silicon, tin, titanium and zirconium oxide hydrates, with pigments having an oxide hydrate of tetravalent.

It is essential to the present invention that the pigments contain support materials and oxide hydrates in addition to gold compounds or colloidal gold. Support Material and Oxide Hydrate Formation A soluble metal compound is generally used in a ratio where the weight ratio of the support material to the oxide hydrate in the pigment, calculated as an oxide, is from 10 to 0.1. Preferred weight ratios are 10 to 1, in particular 6 to 2. When coprecipitation is carried out in the absence of a support material and the support material is subsequently mixed with the coprecipitate, it appears purple upon firing the ornament but has significantly lower thermal stability and color strength than the unreduced pigments according to the invention of the same gold content. Pigments not obtained according to the invention are obtained.

The unreduced pigments according to the invention are substantially water insoluble gold (I) or gold (III) and gold (I) or preferably gold (II) soluble in water or in homogeneous aqueous-organic media and precipitants. It contains a mixture of various insoluble gold compounds obtained during the coprecipitation carried out in the absence of a reducing agent for the gold compound from the compound. Both organic and inorganic gold compounds can be used as soluble gold compounds. Suitable soluble gold compounds are lithium, sodium and potassium dicyanoaurate (I), tetrahaloauric (III) acids and their hydrates, in particular tetrachloroauric acid and its hydrates, lithium, sodium and potassium disulfitoaurate ( I), a gold compound from the range containing the alkali metal dithiosulfatoaurate (I), gold (I) thiolate, especially the gold compound of water-soluble mercaptocarboxylic acid and mercaptoamino acid. Since coprecipitation is carried out using conventional alkaline precipitants, in particular alkali metal oxides, alkali metal silicates, alkali metal sulfides and aqueous or gaseous ammonia, substantially the water insoluble gold (I) and gold (III) compounds are gold oxides. Or hydroxide and gold amine hydroxide and gold sulfide. Since tetrachlorouric acid is a particularly preferred water soluble gold compound and sodium hydroxide solution or aqueous ammonia are particularly preferred precipitants, the substantially water insoluble gold compounds in the unreduced pigments are gold (III) hydroxides and gold amine hydroxides. Water-soluble sulfides or hydrogen sulfides may be used alone or as a precipitating agent with other bases such as sodium hydroxide solution.

Colloidal gold can be prepared by known methods in aqueous or aqueous-organic phases by reducing soluble gold compounds. Handbuch der praparativen anorganischen Chemie by G. Brauer, 3rd edition, volume II, page 1011 describes the reduction of HAuCl ₄ using formaldehyde as a reducing agent in boiling water and K ₂ CO ₃ as a phase acceptor. A method is described; Other possible manufacturing methods are described in another publication, Nature Physical Science, volume 241 (1973), 20-22. The aqueous colloidal gold solution thus obtained is used for coprecipitation of the pigments according to the invention containing colloidal gold.

The gold content of the pigments according to the invention is 0.05 to 10% by weight, preferably 0.5 to 5% by weight. Particular preference is given to pigments having a gold content of from 0.5 to 2.5% by weight.

So far it is not clear why the unreduced pigments according to the invention and the pigments according to the invention which are reduced or directly contain colloidal gold exhibit substantially higher thermal stability during firing of ornaments than prior art pigments of similar composition. Therefore, the pigment according to the present invention can be characterized by the production method. An essential step of the process is the co-precipitation of one or more oxide hydrates with a gold compound or colloidal gold in the presence of a support material in an aqueous or aqueous-organic phase. It is essential to the present invention that no reducing agent for reducing the gold compound to colloidal gold is present during coprecipitation. When a pigment containing at least one gold compound obtained from the coprecipitation is converted to a purple pigment containing colloidal gold, a method of reducing after coprecipitation using a conventional reducing agent or pyrolyzing the gold compound in the pigment at 100 to 300 ° C Is possible. Pyrolysis is less desirable than chemical reduction.

Thus, the pigments according to the invention comprise at least one oxide hydrate of at least one element from the range comprising Al, Si, Sn, Pb, Ti, Zr, Nb, Ta, Sc, Y, La, Ce and Zn. The presence of at least one finely divided support material in which a substantially water-insoluble gold (III) or gold (I) compound or introduced colloidal gold is suspended with a stobable material in the absence of a reducing agent for the gold compound in an aqueous or aqueous-organic phase. And a solution containing at least one soluble compound, at least one water soluble gold compound, or colloidal gold of a metal contained in the oxide hydrate and at least one precipitant, the weight ratio of the support material to the oxide hydrate calculated as the oxide 10 to 0.1, in particular 10 to 1, the gold content in the pigment is 0.05 to 10% by weight, in particular 0.5 to 5% by weight), co-precipitate When separating from the liquid phase to dry or converting an insoluble gold compound containing coprecipitate to colloidal gold, the coprecipitate is treated with a reducing agent in the aqueous phase and then separated from the aqueous phase and dried or dried coprecipitate is 100 It may be prepared by the step of heat treatment at 300 ℃.

Ag, Cu, Co, Ni, Ru, Rh, Pd, Os, Ir and Pt in addition to the components essential to the present invention, namely one or more support materials, one or more oxide hydrate forming metal compounds and one or more soluble gold compounds or colloidal gold solutions A water soluble tint modifying compound may also be present during coprecipitation. These color tone modifying components also precipitate substantially like hydroxides or oxide hydrates during coprecipitation.

Coprecipitation is carried out in aqueous or aqueous-organic phase. If organic solvents are present they are water soluble organic solvents such as water soluble alcohols, ketones and ethers. Preferably, the coprecipitation proceeds in an aqueous phase or at least primarily in an aqueous phase. Water-soluble organic solvents are generally used only when one reaction component, such as a gold compound or oxide hydrate forming compound, is not sufficiently water soluble or the aqueous solution of such a compound is not stable. Coprecipitation is usually carried out at 5 to 100 ° C., especially at 15 to 30 ° C., with vigorous stirring.

Soluble metal compounds used in the process of the invention are compounds which can be precipitated by varying the condensation and / or pH value after hydrolysis as an oxide hydrate or oxide forming gel, in an aqueous phase or an aqueous organic phase. Suitable soluble compounds include, for example, tin chloride (IV) and its hydrates, tin sulfate (IV) dihydrate; AlCl ₃ , aluminum acetate, aluminum sulfate, aluminum nitrate; Zirconium sulfate (IV) tetrahydrate, Zr (NO ₃ ) ₄ , zirconium chloride hydrate; Chlorides, nitrides or acetates of scandium, yttrium, lanthanum, cerium and zinc; Water soluble silicates, especially water glass; Titanium sulfate. Preferred sources of oxide forming gels of Si, Ti, Zr are monomeric or oligomeric alkoxy compounds of these elements, wherein the alkoxy group preferably has 1 to 3 carbon atoms, and between two metal atoms other than the alkoxy group OH groups and oxygen bridges may also be present. Examples include Si (OC ₂ H ₅ ) ₄ , Ti (OC ₂ H ₅ ) ₄ , Zr (OC ₂ H ₅ ) ₄ , (HO) _n-3 (C ₂ H ₅ ) _n Si-O-Si (C ₂ H ₅ ) _n (OH) _n-3 where n is 1, 2 or 3.

One or more dissolved oxide hydrate-forming compounds, one or more dissolved gold (I) or preferably gold (III) compounds or colloidal gold introduced as a solution and any one or more dissolved color-modifying compounds are aqueous or aqueous-organic. Coprecipitation to precipitate using one or more precipitants in the presence of a finely divided support material suspended therein in a phase can be carried out in various ways. Precipitation agents are generally basic compounds or compounds which have a basic function in the aqueous phase, in particular alkali metal hydroxides or ammonia. For example, it may be convenient to further use water-soluble sulfides or hydrogen sulfides. The pH value is simply determined by these precipitants. These precipitants should also allow the oxide hydrate forming compound and the gold compound or the colloidal gold introduced and any color modifying compound to precipitate almost simultaneously. During the coprecipitation, particles of the support material suspended in the reaction mixture are surrounded by the coprecipitation. Upon coprecipitation, the precipitant is initially introduced into a suspension containing a support material, a solution of an oxide hydrate forming compound, a solution of gold or colloidal gold and a solution of any color tone modifying compound or a mixture of the mentioned solutions into the initial mixture. Can be introduced. The ratio of the amounts of acid present in the alkaline precipitant and / or formed by the hydrolysis of the oxide hydrate forming compound is adjusted to each other so that coprecipitation proceeds as completely as possible. The pH value at the end of the coprecipitation can be in the acidic or alkaline range, for example in the range of 0.5 to 12. As is apparent from the examples, preferred final pH values are from about 0.5 to about 10.5. Coprecipitation can be controlled by temperature as well as pH value. In another embodiment of coprecipitation, the oxide hydrate forming compound solution and the precipitant aqueous solution or precipitant combination may be introduced simultaneously into the support material and the suspension containing the gold compound or colloidal gold dissolved therein. In another embodiment, the precipitant solution may be introduced into a suspension containing the support material, dissolved gold compound or colloidal gold, and dissolved oxide hydrate forming compound. When choosing a method of preparing coprecipitation using a solution of colloidal gold, it should be borne in mind that colloidal gold is sensitive to the electrolyte content, affecting the particle size of the Au particles and consequently the color. After coprecipitation, usually with vigorous stirring, the resulting coprecipitate can be separated from the liquid reaction medium in a conventional manner, washed and then dried.

To prepare pigments containing colloidal gold, reducing agents for conventional gold compounds in the presence of any color modifying compound before, preferably after separation, of the coprecipitate containing the insoluble gold compound from the liquid reaction medium Can be handled using Reduction typically proceeds in an aqueous medium at room temperature or mild elevated temperatures. Examples of effective reducing agents are the mentioned salts based on sulfite, thiosulfate, dithionite, nitrite, phosphite, hypophosphite and acids, hyponitrite H ₂ N ₂ O ₂ , oxohyponite H ₂ N ₂ O ₃ , hydrazine, hydroxylamine and salts thereof, hydrogen peroxide, metal hydrides, and especially complexes of metal hydrides with aldehydes such as formaldehyde, urotropin and glucose. The reducing agent is preferably used in a superstoichiometric amount relative to the amount required to reduce the gold compound and any color tone modifying compound. The reduced pigment is separated from the aqueous reaction medium and dried.

Instead of converting the gold compound in the coprecipitate to colloidal gold using a reducing agent, the gold compound may be converted by thermal decomposition. For this purpose the unreduced coprecipitate is heat treated at 100 to 300 ° C., which treatment is preferably carried out in a fluidized bed reactor. When heat treated at 300 ° C. or lower, the conversion of the oxide hydrate to oxides containing no hydroxyl groups is not complete. Pigments according to the invention containing colloidal gold can be obtained not only by chemical reduction of the above-mentioned coprecipitates or by heat treatment thereof, but also by directly using a colloidal gold solution in the coprecipitates. This embodiment has a lower consumption of reducing agent and a higher space time yield than a method comprising a reduction step after coprecipitation.

The pigments according to the invention are used as colored glazes, enamels, plastics, glass colorants and adornment colorants in the same way as pigments in the prior art, and thus can also be used to produce purple ceramic adornments. Purple reduced pigments are preferably suitable for coloring plastics. Pigments specifically tailored to the specific application can be used: pigments based on low melting frit for glass colorants, pigments based on high melting point frit for magnetic colorants, rapid firing colorants and colorants for wall tiles. The rheological behavior of glazes and enamels is not improved by pigments adapted to the glass frit of glazes and enamels. As a decorative use, pigments are typically converted into pastes with liquid media, paste screens printed on a moving support and transfer agents which provide coatings in a known manner. The transfer agent is moved over the support in a known manner and then stowed. The firing temperature depends on the material to be decorated. Although firing of ceramic support base ornaments has been mainly carried out at 800 to 900 ° C., the benefits of so-called high temperature rapid firing are now increasing, and pigments can be stowed at temperatures above 1000 ° C., in particular from 1100 to about 1250 ° C. have.

A significant advantage of the pigments according to the invention is that they are better in high temperature stability than when using similar types of pigments of the prior art, and are therefore more heavily colored and glossy in decoration, often yielding opaque and matte ornaments. You may. This high temperature stability is distinguished in that the pigment becomes less severely blurred upon high temperature firing than the pigments of the prior art. Another advantage of the pigments according to the invention containing gold compounds can be obtained in a particularly simple manner and makes the reduction step unnecessary since the actual reduction of gold compounds to colloidal gold does not occur during firing. Various pigments of different hue can be obtained by selection of the support material and the oxide hydrate forming compound.

The following examples illustrate the invention in more detail. The examples cover both the preparation and the use of the pigments according to the invention as compared with the use of the pigments prepared using the methods of the prior art.

Example 1

525 g of high temperature rapid calcination (HTS) frit (product number 90234 of Cerdeck AG, consisting essentially of SiO ₂ , PbO, CaO, B ₂ O ₃ and SnO ₂ ; grain size distribution: 90% less than 10 μm), 1000 ml of concentrated ammonia water and 1700 ml of water are introduced into a glass beaker. With stirring and a solution (pH less than 1) made from a water 1250ml in the tin tetrachloride pentahydrate (SnCl ₄ · 5H ₂ O) amount of tetra-chloroauric acid hydrate (HAuCl ₄ · H ₂ O) corresponding to 305g and 8.8g gold Add drop wise within 15 minutes. The pH is lowered from 12.5 to 9 during addition at room temperature. The resulting pigment, which is rarely colored and has not been reduced, is filtered, washed and dried at 60 ° C. The calculated weight ratio of glass frit to oxide based oxide hydrate is 4 in the case of SnO ₂ . The gold content of the pigment is 1.34% by weight relative to the sum of the glass frit and SnO ₂ .

The resulting pigment was converted to a paste (56 parts by weight of pigment and 44 parts by weight of medium) using a printing medium (8082 manufactured by Chredde AG) and applied to a glazed magnetic surface using a known indirect screen printing method, 30 Stove at 1220 ° C. for minutes. Typical purple color is obtained; Brightness is measured using a Hunter Lab spectrophotometer and converted to the L ^* , a ^* and b ^* values of the CIE-Lab system (DIN 5033, part 3).

L = 38; a = 29; b = 3.1 (hunter)

L ^* = 45.8; a ^* = 34.9; b ^* = -3.9 (CIE-wrap)

The colored magnetic surface obtained above was stowed twice at 1220 ° C. for 30 minutes to investigate its restoring stability. There is no visually discernible color change.

L = 38.6; a = 29.3; b = 3.26 (Hunter)

L ^* = 45.5; a ^* = 34.3; b ^* = -4.2 (CIE-wrap)

Example 2

Suspension of 100 ml of 32% aqueous ammonia, 100 ml of water, 0.1 g of AgCl (to improve the color tone), and glass frit (product number 10150 from charddec AG) with lead as the main ingredient SiO ₂ , B ₂ O ₃ and Na ₂ O Prepared as this initial mixture. Then, a solution prepared from SnCl ₄ · 5H ₂ O and 200 g of HAuCl ₄ · H ₂ O in 200 ml of water is added dropwise to the suspension with stirring. The final pH value is 8.5. The resulting pigment is filtered off, washed and dried at 60 ° C. The weight ratio of glass frit to SnO ₂ is 1.6 and the gold content is 2.1 weight percent with respect to the sum of the frit and SnO ₂ . After indirect printing on glazed porcelain and firing at 1220 ° C. for 30 minutes, the brightness (CIE-wrap) is as follows:

L ^* = 42.7; a ^* = 20.4; b ^* =-6.9.

Example 3

A suspension of 200 ml of water, 150 ml of a 5% NaOH solution and glass frit (product number 10150 from Cherdec Age) without lead is prepared as the initial mixture. Then, 17.5 g of tin tetrachloride in 50 ml of water and a 0.2 g solution of gold in the form of HAuCl ₄ · H ₂ O are added dropwise with stirring. The resulting pigment is filtered off, washed and dried at 60 ° C. The weight ratio of glass frit to SnO ₂ is 1.3 and the gold content is 1.14 wt% based on the sum of frit and SnO ₂ .

After 30 minutes of glazing porcelain at 1220 ° C., the brightness (CIE-wrap) is as follows:

L ^* = 38.8; a ^* = 32.1; b ^* = -5.7.

Example 4

A suspension of 100 ml of water, 27 g of ZrOCl ₂ · 8H ₂ O, 0.1 g of gold in the form of HAuCl ₄ · H ₂ O and a lead free glass frit (product number 10150 from Cherdec Age) are prepared as an initial mixture. A solution prepared from 20 g of sodium water glass and 35 ml of 5 M sodium hydroxide is added dropwise to the suspension with stirring. The resulting pigment is filtered off, washed and dried at 60 ° C. Next, indirect printing and stoving are usually performed. CIE-Lab brightness is as follows:

L ^* = 52.0; a ^* = 27.7; b ^* = + 5.8.

Example 5

A suspension of 100 ml of water, 60 ml of concentrated ammonia water and 30 g of quartz powder (SiO ₂ ) is prepared as an initial mixture. A solution prepared from 17.5 g of tin tetrachloride · 5H ₂ O in 80 ml of water and 0.2 g of gold in the form of HAuCl ₄ · H ₂ O is added to the suspension with stirring. The final pH value is less than 10. The resulting pigment is filtered off, washed and dried at 60 ° C. The pigment is converted into a paste in a conventional manner and applied to a glazed porcelain and stowed at 1220 ° C. for 30 minutes. CIE-lab brightness is as follows: L ^* = 61.8; a ^* = 11.8; b ^* = -2.1. The ratio of SiO ₂ to SnO ₂ is 4 and the gold content is 0.53% by weight relative to the sum of SiO ₂ and SnO ₂ .

Example 6

The pigment obtained according to example 1 is mixed with 0.01% permanent red (Cheist). In this way a pigment powder of a color similar to the subsequent calcined color is obtained. The powder is applied to a glazed magnetic surface in a similar manner to Example 1 and stowed (1220 ° C., 30 minutes). There is little difference compared to the results obtained in Example 1: L ^* = 48.2; a ^* = 33.3; b ^* = -4.1.

Example 7

50 ml of tetraethyl orthosilicate are stirred in a suspension prepared from 0.18 g of NaAuCl ₄ (0.1 g of Au), 9 g of ZrO ₂ , 25 ml of ethanol and 25 ml of concentrated hydrochloric acid. The mixture is stirred for 5 hours and then dried at 60 ° C. in a drying cabinet. A gray-purple pigment is obtained.

Example 8

26 g of a high temperature rapid firing (HTS) frit (product number 10150 from Cerdec AG), 20 ml of concentrated ammonia water and 100 ml of water are placed in a glass beaker. Then, 15.3 g of tin tetrachloride and pentahydrate in 60 ml of water and 0.36 g (Au 0.2 g) of HAuCl ₄ · H ₂ O are added dropwise with stirring. The resulting pale yellow suspension is combined with 160 ml of a 5% by weight solution of H ₃ PO ₂ and heated at 80 ° C. for 2 hours. After several hours, the suspension shows the typical color of the purple colorant. The resulting pigment is filtered off, washed and dried at 60 ° C. The weight ratio of frit to SnO ₂ is 4 and the gold content (relative to the sum of frit and SnO ₂ ) is 0.61 wt%. Typically after application and firing (1220 ° C., 30 minutes), the CIE-wrap brightness is as follows: L ^* = 53.6; a ^* = 28; b ^* = -4.2.

Example 9

5 g of the pigment obtained according to Example 1 are suspended in 50 ml of water. Then 10 ml of 8% by weight hydrazinium hydroxide are stirred therein and the mixture is stirred for 1 hour. The suspension is grayed out. The resulting purple pigment is filtered, washed and dried at 60 ° C., then applied to a magnetic surface using known indirect screen printing methods and stowed at 1220 ° C. for 30 minutes. Typical CIE-wrap brightness of purple colorants was found as follows: L ^* = 42.7; a ^* = 28.1; b ^* = -5.1.

Example 10

5 g of the pigment obtained according to Example 1 are suspended in 50 ml of water. Then 10 ml of 5% by weight H ₃ PO ₂ solution is stirred therein and the mixture is stirred at 80 ° C. for 1 hour. The suspension becomes blue-purple. The resulting pigment is filtered, washed, dried at 60 ° C. and then applied to porcelain using known indirect screen printing methods and then stowed at 1220 ° C. for 30 minutes. Typical purple color appears. Hunter brightness corresponding to CIE-lab brightness is as follows: L = 30; a = 31; b = -2; L ^* = 36.0; a ^* = 38.0; b ^* = -2.8.

Example 11

The pigment obtained according to Example 1 is heat treated at 250 ° C. for 2 hours in a fluidized bed. The resulting pigment is applied to the magnetic surface using known indirect screen printing methods and stowed at 1220 ° C. for 30 minutes. Typical purple color appears. Hunter brightness corresponding to CIE-Lab brightness is: L = 38.8; a = 18.5; b = -1.9; L ^* = 45.5; a ^* = 22.6; b ^* = -2.4.

12 to implementation

Examine the following parameters: (i) Influence of the weight ratio of the support material to oxide hydrate calculated as oxide and (ii) Influence of firing temperature. Unreduced pigment is prepared in a similar manner to that of Example 1. The support material used is a high temperature rapid calcining frit (product number 10150 from Cherdeck AG), using SnCl ₄ · 5H ₂ O as the oxide hydrate forming compound and HAuCl ₄ · H ₂ O as the soluble gold compound. The gold content of all pigments (relative to the sum of frit and SnO ₂ ) is 1.3% by weight. After coprecipitation, the pigment was washed and dried (60 ° C.), then converted to a paste in a similar manner to Example 1, and then the paste was applied to the glazed magnetic surface by indirect screen printing and stowed at 1220 ° C. for 30 minutes. do. The L ^* a ^* b ^* values for DIN 5033 (part 3) are shown in the following table. From these values (i) lightness only depends slightly on the ratio of the support material to the oxide hydrate calculated as oxide and (ii) the pigments exhibit elevated temperature stability, ie they are stowed at 1220 ° C instead of 1140 ° C or 1180 ° C. If it is, it is slightly blurred.

Heating temperature Weight ratio of frit to oxide hydrate calculated as oxide CIE-Lab L ^* a ^* b ^* 1140 ℃ 942.31.51 38.6 27.1 -1.637.8 31.0 -1.938.6 27.6 -1.840.6 26.7 -2.140.4 27.6 -2.1 1180 ℃ 942.31.51 39.6 24.3 -1.039.5 27.5 -1.839.5 26.3 -1.941.2 25.2 -2.338.9 27.9 -1.9 1220 ℃ 942.31.51 45.7 19.2 +0.841.1 23.3 -0.442.7 21.7 0.044.3 21.2 -1.842.2 23.0 -2.5

Example 13

Coprecipitation is carried out in a similar manner to the method of Example 1 in the absence of frit using SnCl ₄ · 5H ₂ O and HAuCl ₄ · H ₂ O. Then mix the frit in it.

The composition is the same as in Example 1, where Au is 1.34% by weight and the weight ratio of frit to oxide hydrate calculated as oxide is 4. L ^* a ^* b ^* values are shown in the following table.

CIE-Lab L ^* a ^* b ^* Example 1 (according to the invention) 45.8 34.9 -3.9 Example 13 (Not in accordance with the present invention) 73.6 8.6 -2.1

Example 14

Reduced Pigment: The effect of the amount of reducing agent used to reduce 10 g of the unreduced pigment obtained according to Example 1 is investigated. After conventional application and firing, the pigment brightness is shown in the following table.

H ₃ PO ₂ (50%) 1ml H ₃ PO ₂ (50%) 10ml L ^* a ^* CIE-wrap ^* 36.038.5-2.5 54.515.9-2.3

Example 15

a) 17.5 g of high temperature rapid firing (HTS) frit (Product No. 90234 of Cerdec AG), 10 ml of 25% ammonia and 60 ml of water are placed in a glass beaker as an initial mixture. 10.18 g of tin tetrachloride pentahydrate (SnCl ₄ · 5H ₂ O), 0.29 g of Au in the form of tetrachloroauric acid and 50 ml of water are added dropwise within 10 minutes with stirring. At room temperature, the pH drops from 11.8 to 3.3 during the addition. The resulting white coprecipitate is filtered off, washed and dried at 70 ° C. The resulting pigments constituting the direct upholstery colorant are converted into a paste in the printing medium (80820 from Chredek AG) (56 parts by weight of pigment and 44 parts by weight of medium) and using a known indirect screen printing method (100T screen fabric). It was then applied to the glazed magnetic surface and stowed at 1220 ° C. with a 90 minute firing cycle in a gas pushed-bat oven. Brightness is measured using a Hunter Lab spectrophotometer and converts the L ^* , a ^* and b ^* values of the CIE-Lab system (DIN 5033, part 3):

L ^* = 82.15; a ^* = 6.56; b ^* = -1.77

b) and c):

Example 15a is repeated while increasing the amount of ammonia water used during coprecipitation while maintaining a constant batch size. The amount of NH ₃ used, the initial and final pH values and the L ^* a ^* b ^* values of the stowed pigments are shown in the following table.

Example 15a 15b 15c NH ₃ solution (25%) ml 10 20 40 Initial pH 11.8 12.1 12.5 Final pH 3.3 9.6 10.3 L ^* 82.1 46.2 36.7 a ^* 6.6 25.9 29.3 b ^* -1.8 -2.9 -1.4

d), e) and f):

Half of the coprecipitation prepared according to Examples 15a-15c is suspended in 50 ml of water as a wet filtrate cake. 1 g of hypophosphorous acid (50%) is added to each and the mixture is stirred at 80 ° C. for 2 hours. The purple coprecipitate obtained in each case is filtered off, washed and dried at 70 ° C. Print and dry in a similar manner to Examples 15a-15c. L ^* a ^* b ^* values are shown in the following table.

Example 15d 15e 15f Coprecipitate used in the reduction step of each example 15a 15b 15c L ^* 74.2 47.5 41.6 a ^* 15.1 25.5 24.8 b ^* -4.2 -3.8 -2.2

Example 16

A solution prepared from 10.18 g of tin tetrachloride pentahydrate (SnCl ₄ · 5H ₂ O), 0.29 g of gold in the form of tetrachloroauric acid and 50 ml of water was subjected to a high temperature rapid firing (HTS) frit (product no. Together with the initial mixture into a glass beaker. 0.49 g of sodium sulfide (about 35%) dissolved in 12 ml of 5 M sodium hydroxide solution is added dropwise within 10 minutes with stirring. At room temperature, the pH value increases from 0.15 to 0.86 during the addition. The resulting dark brown coprecipitate is filtered off, washed and dried at 70 ° C. The resulting decorative colorant was converted to a paste in the printing medium (80820 from Chredek AG) (57 parts by weight pigment and 43 parts by weight medium) in a conventional manner, and glazed porcelain using a 100 T screen fabric with indirect screen printing. The surface is applied and stowed at 1220 ° C. in a 90 minute firing cycle in a gas pushed bat oven. Brightness is measured using a Hunter Lab spectrophotometer and converted to L ^* , a ^* and b ^* values of the CIE-Lab system.

L ^* = 58.49; a ^* = 15.24; b ^* = -0.90.

Example 17

High temperature rapid firing (HTS) frit containing lead dissolved in 50 ml of water (Product No. 90234 of Chredek AG; Grain size distribution: 90% less than 10 μm) 17.5 g, 12 ml of 5M sodium hydroxide solution and 0.49 g of sodium sulfide It is introduced into the glass beaker as a mixture. 10.18 g of tin tetrachloride pentahydrate (SnCl ₄ · 5H ₂ O), 0.29 g of Au in the form of tetrachloroauric acid and 50 ml of water are added dropwise within 10 minutes with stirring to a strong alkaline suspension having a pH of 13.30. Add at room temperature. At the end of copulation the pH value is 1.1. The resulting brown coprecipitate is filtered off, washed and dried at 70 ° C. After printing and firing, the brightness of these decorative colorants is as follows:

L ^* = 44.0; a ^* = 31.8; b ^* =-4.9.

Comparing Examples 15, 16 and 17 with the same support material and oxide hydrate, the same support material to oxide hydrate ratio, and the same gold content, the type of co-precipitation and precipitant had a decisive effect on the color of the pigment (decorative colorant). Becomes clear.

Example 18

Lead free high temperature rapid firing (HTS) frit dissolved in 50 ml of water (product no. 901368 from cherdec AG, consisting essentially of SiO ₂ , CaO, Al ₂ O ₃ , B ₂ O ₃ and Na ₂ O; granule size distribution: 17.5 g of 90% less than 8 μm), 20 ml of 5M sodium hydroxide solution and 0.49 g of sodium sulfide (about 35%) are introduced into the glass beaker as an initial mixture. 10.18 g of tin tetrachloride pentahydrate (SnCl ₄ · 5H ₂ O), 0.29 g of Au in the form of tetrachloroauric acid and 50 ml of water are added dropwise within 10 minutes with stirring. At the end of copulation the pH value is 1.9. The resulting brown coprecipitate obtained at room temperature is filtered off, washed and dried at 70 ° C. After printing and firing, the brightness of the pigments tested directly as decorative colorants is as follows:

L ^* = 47.6; a ^* = 29.0; b ^* = -4.5.

Example 19

25 g of high temperature rapid calcination (HTS) frit dissolved in 50 ml of water, consisting of product number 90234 of Cherdeck AG, SiO ₂ , PbO, CaO, B ₂ O ₃ and SnO ₂ ; grain size distribution: 90% less than 10 μm 50 ml of concentrated ammonia water and 200 ml of water are introduced into the glass beaker as an initial mixture. A mixture of 17.5 g of tin tetrachloride pentahydrate (SnCl ₄ · 5H ₂ O) in 30 ml of water and 37 ml of an aqueous colloidal gold solution having a gold content of 10 mg / ml prepared from HAuCl ₄ by reducing formaldehyde was added dropwise within 10 minutes while stirring. do. At room temperature, the pH value drops from 12.5 to 9 during the addition. The resulting purple coprecipitate is filtered off, washed and dried at 60 ° C.

The resulting pigment, with a gold content of 1.13% by weight, was converted to a paste in the printing medium (80820 from Chredek AG) (56 parts by weight of pigment and 44 parts by weight of medium), and the magnetic surface glazed by the known indirect screen printing method. Apply and stow at 1220 ° C. for 30 minutes. Brightness is measured using a Hunter Lab spectrophotometer and converted to L ^* , a ^* and b ^* values of the CIE-Lab system (DIN 5033, part 3):

L ^* = 56.4; a ^* = 22.0; b ^* = -4.1 (CIE-wrap).

The pigments according to the invention are better in high temperature stability than pigments of the prior art of similar type and can obtain darker colored upholstery.

Claims (11)

Substantially, it includes at least one finely divided support material (a) from a stoavable material, in particular glass frit, Al, Si, Sn, Pb, Ti, Zr, Nb, Ta, Sc, Y, La, Ce and Zn A support material and an oxide composed of at least one oxide hydrate (b) of at least one element and at least one water soluble gold (III) or gold (I) compound or colloidal gold (c) The hydrate is present in a weight ratio of 10 to 0.1 and the gold content of the pigment is 0.05 to 10% by weight), one or two or more oxide hydrates in the absence of a reducing agent for gold compounds in the presence of a support material in an aqueous or aqueous-organic phase One or more soluble compounds of metals present in oxide hydrates by coprecipitating with water-insoluble gold compounds or colloidal gold (wherein at least one soluble gold compound or solution containing colloidal gold) And at least one precipitant is used), when converting the water-insoluble Au compound present in the co-precipitate into colloidal gold, reducing and co-precipitating by using a conventional reducing agent or by pyrolysis at 100 to 300 ° C. Pigment suitable for producing purple ceramic ornaments at high temperature firing, obtainable as a. The method according to claim 1, characterized in that the glass frit is contained as a support material, the oxide hydrate of Sn or Zr, in particular Sn, is contained as the oxide hydrate, and the weight ratio of the glass frit to the oxide hydrate calculated as the oxide is 10 to 1. Pigment. A gold (III) hydroxide, a gold (III) amine hydroxide or a gold sulfide as a gold compound, characterized in that the gold content of the pigment is 0.5 to 5% by weight. Pigment. The water-insoluble gold compound according to claim 1 or 2, using a reducing agent from the range comprising aldehyde, hydrazine, sulfite, dithionite, thiosulfate, phosphite, hypophosphorous acid and hypophosphite. , In particular a colloidal gold obtained by the reduction of gold (III) hydroxide or gold (III) amine hydroxide in an amount of 0.5 to 2.5% by weight. The method according to any one of claims 1 to 4, wherein at least one substance from the range containing alkali metal hydroxide, alkali metal silicate, alkali metal sulfide and / or ammonia is used as precipitant and the pH value at the end of coprecipitation is about Pigment from 0.5 to about 10.5. At least one oxide hydrate of at least one element and at least one substantially water insoluble gold (III) from the range comprising Al, Si, Sn, Pb, Ti, Zr, Nb, Ta, Sc, Y, La, Ce and Zn Or a reducing agent for a gold compound in the presence of at least one finely divided support material from the range of substantially stoving materials in which the gold (I) compound or the introduced colloidal gold is suspended therein in an aqueous or aqueous-organic phase. Co-precipitated in the absence of (wherein a solution containing one or more soluble compounds of metals contained in oxide hydrates, one or more water soluble gold compounds or colloidal gold, and one or more precipitants are used as Used in an amount of 10 to 0.1 by weight, and the gold content in the pigment is 0.05 to 10% by weight), The coprecipitate is separated from the liquid phase and dried (where the insoluble gold compound contained in the coprecipitate is converted to colloidal gold), The pigment according to any one of claims 1 to 5, characterized in that the coprecipitate is treated with a reducing agent in an aqueous phase and the dried or dried coprecipitate separated from the aqueous phase and heat treated at 100 to 300 ° C. Manufacturing method. The method of claim 6, wherein at least one precipitant from the range comprising alkali metal hydroxides, alkali metal silicates, alkali metal sulfides and ammonia is used for coprecipitation, and (i) the precipitant is used as a solution of a support material, an oxide hydrate forming compound, and It may be initially introduced into a suspension containing a solution of a gold compound or a mixture of these solutions may be introduced into the initial mixture, or (ii) an oxide hydrate forming compound solution and an aqueous solution of a precipitant may be added to a suspension containing a support material and a dissolved gold compound. Or (iii) introducing a precipitant solution into a suspension containing the support material, the dissolved gold compound and the dissolved oxide hydrate forming compound. 8. Process according to claim 6 or 7, characterized in that the coprecipitation is carried out by a method wherein the final pH value is about 0.5 to 12, in particular about 0.5 to 10.5. The compound according to any one of claims 6 to 8, wherein dithionite, thiosulfate, sulfite, phosphite, hypophosphorous acid, hypophosphite, formaldehyde, eurotropin, hydrazine, hydroxylamine, hyponitrite A reducing agent from the range comprising (H ₂ N ₂ O ₂ ), oxohyponitrite (H ₂ N ₂ O ₃ ) and glucose is used as reducing agent. The glass frit is used as a support material, tin (IV) compounds, in particular SnCl ₄ .5H ₂ O, are used as oxide hydrate forming soluble compounds, and HAuCl ₄ is a soluble gold compound. Used as a method. Use of a pigment according to any one of claims 1 to 5 for producing purple ceramic ornaments, in particular purple ornaments produced by high temperature firing.