DE3224867A1 - Colorants and pigments of sphene structure, process for their preparation and their use - Google Patents

Abstract

The present invention relates to colorants and pigments of sphene structure of the system x CaO . SnO2 . SiO2 which additionally contain at least one colouring guest component, processes for their preparation and their use.

Description

Color bodies and pigments with a spherical structure, process too

Their preparation and their use The present invention relates to Color bodies and pigments with, Sphenstruktur, the additional at least one coloring Have guest components, processes for their production and their use.

Color bodies with a spherical structure are characterized by their high temperature stability and have been known in pink to purple-red color since the 13th century.

The mineral of this color is the malayite with the formula CaO.SnO2.SiO2 (also called tin sphene); the red color is due to the incorporation of Cr3 + ions into the Due to host lattice.

Synthetically manufactured hot pink color bodies and other color bodies with Sphere structure, as described in DE-A 2 038 007, contain about equal atomic proportions of Ca, Sn and Si.

Ceramic pink color bodies, such as those obtained according to DE-A 3,023,941, are also used and which have the advantage of being lead-free contain Ca, Sn and Si in approximately equal atomic proportions.

The molar ratio (CaO + Si02): SnO2 is about 2.

The production price of the Sphen color bodies is essentially due to the Determined Sn content. It is therefore desirable to use color bodies and pigments with a spherical structure provide that with comparable color properties, small proportions of Sn exhibit.

The aim of this invention is thus to provide products of this type to deliver.

Surprisingly, it has now been found that these requirements are met are made up of color bodies and pigments with a spherical structure of the general formula x CaO. y SnO2 z SiO and a proportion of additional coloring guest components in which the molar ratio of less than 1.3 and the ratio of y x + z x y Z greater than is 3.

Those color bodies and pigments in which, moreover, the molar ratio of z / x is greater than.

All systems can be used as coloring guest components according to DE-A 2 038 007 in the host.

lattice of the tin-Sphens can be installed. However, these are preferred Cr (III) - and / or Au (III) - and / or La (III) compounds, so that you can get pink Types receives.

The present invention not only leads to cheaper color bodies and pigments but also to products with improved colors. If the color of the enamels or ceramic glazes (semiopake or transparent frits) judged by the Hunter color measurement system (from Hunter, Fairfax, Virginia, USA), sc the red value (+ a) can be increased by the measures according to the invention and the yellow value (+ b) be lowered. If the L-values are reduced at the same time (see table l) the result is a more saturated and brilliant one compared to the prior art Shade of red.

The upper limit for the ratio (CaO + SiO2): SnO2 is thereby stipulated that the sphenoid structure must still be present by X-ray. Particularly good results are achieved with values greater than 4.

The color bodies and pigments according to the invention can thereby be obtained that the starting and guest components used for the production are homogeneous mixed, annealed at temperatures between 5000C and 14000C and finally on the mixed grain size can be ground up.

As raw materials for the components in the host grid, they all come from Annealing oxide-forming compounds in question. CaO and SnO2 can be used directly or from the corresponding hydroxides, carbonates, sulfates, oxalates, formates, Halides and metals are obtained, with tin the oxidation state +2 and +4, depending on the existence of the respective connection, come into consideration. Preferred white lime hydrate and tin powder are used.

The raw materials for the SiO2 component are silicon powder, silicon halides, Quartz powder, precipitated or pyrogenic silicas and silica sol are used. epreferred highly dispersed silicas are used as SiO2 sources.

The coloring guest components are also used as oxides or in the form of compounds that form corresponding trivalent oxides on annealing. Compounds of other oxidation states also come into consideration here, which occur during of the body glow and preparation processing into the oxidation state (+ 3) skip. The concentration of the total coloring oxides should be below 10 MOL-% are based on the calcium used.

Cr203 pigments are preferably used as the raw material for the Cr (III) component and / or pigments of the type Me1 CrIII (Si2O6) with Me1 = Li and Na, as they are in the DE-A 3 103 818 are described. By suitable selection of these pigments as raw materials for pink color bodies, the pink-red coloring can be used in shades of neutral red to be controlled purple-red. So you win e.g.

with the lithium compound LiI CrIII (Si2O6) a more bluish pink than with the sodium compound.

The raw materials used should be mixed intensively, whereby it is advisable to use powder that is as finely divided as possible. A wet mix, e.g. a ball mill, is preferable to a dry mix.

The annealing of the raw material mixture takes place between 5000C and 14O00C, preferably between 12000C to 13500C in rotary drum, t4uffel, chamber, plate ovens or in other suitable devices.

In a preferred method of making color bodies and Pigments with a spherical structure are used in a preliminary stage to produce tin powder and hydrate of lime between 5000C and 1400 ° C, preferably between 8000C and 1000 ° C, oxidized annealed and the homogenized overall system is then heated between 5000C and 14000C, preferred between 1200 ° C and 1350 ° C. For the homogenization of the.

The precursor product is generally a dry milling, e.g. in a pin or cross beater mill is sufficient, but the BET surface area should must be greater than 1 m / g before further use.

The color bodies and pigments according to the invention are outstandingly suitable for coloring enamels and ceramic glazes.

The invention is explained below by way of example.

Examples 1 and 2 (comparative example) (see Table 1) Equimolar amounts of Ca (OH) 2, amorphous SnO2 and quartz powder (98% by weight below 15 p particle size) mixed wet and the coloring components added: These are chromium oxide (predominant Particle size 0.3 m) and in example 2 additionally La2O3 (99.9 Zig). After drying of the raw material mixture, the product was ground in a cross beater mill and Annealed for 2 hours at 13000C. The pink colored body became after cooling ground wet in a ball mill, filtered off and washed with 1.5 l of water. That dried product was then used for deagglomeration in a cross beater mill ground.

Examples 3 - 10 (Table 1) According to the molar shown in Table 1 Composition and the specified conditions, the product was analogous to the example 1 and 2 produced. It was annealed for 1 hour at 13000 ° C. in each case.

In Example 6, Kosmochlor NaCr (Si206) with a Cr203 source was used BET surface area of 4.3 m2 / g used, in example 1'-Spodumene LiCr (Si206) with a BET surface area of 4.2 2 / g. In Examples 8 to 10, a highly disperse silica was used used - Wessalon S R - a commercial product from Degusa AG -87% by weight SiO2, BET surface area 160 m2 / g.

In example 10, Sn powder (chem.

pure, from Merck) and Ca (OH) 2 in the specified molar composition wet mixed, dried and deagglomerated for the entire raw material batch. Afterward preheating took place at 800 ° C. (4 hours) in the electric furnace. The intermediate product obtained consists mainly of calcium stannate. It got wet with Wessalon S 6 and Cr203 mixed and worked up as in Comparative Examples 1 and 2.

All examples given showed in the X-ray powder diagram according to Debye-Scherrer a well crystalline phase with a spherical structure.

For assessing the color in the TiO2-containing semi-opaque Blechemail WF 3701 (commercial product from Bayer AG) (Table 1), 4% by weight of color bodies were used. The enamelling was carried out according to the state of the art (2.5 minutes for 8300C).

To determine the relative color strength according to DIN 53 234, the The color bodies described are ground in a sand mill until the pigment is fineness (BET = approx. 10 m2 / g).

The dried and deagglomerated mixed pigment was in a varnish based on an alkyd resin with a medium oil content (AlkydalC F 48 - commercial product from Bayer AG) with a Red Devil shaker for 30 minutes (10 % PVC). The relative color strength was determined in an opaque layer on polyester film.

Example 1 with a color strength of 100 was used as a reference sample.

Table 1: Manufacture of pink stains with molar composition Manufacture of color coordinates game of the raw material mixture conditions of the enamelling in oxides: CaO SnO2 SiO2 (CaO + SiO2): SnO2 SiO2: CaO Cr2O3 La2O3 L a b (x) (y) (z) x + z (x / y) # # y V1 1.0 1.0 1.00 2.0: 1 1 0.02 - 2h, 1300 ° C 75.09 7.92 4.17 V2 1.0 1.0 1.02 2.0: 1 0.02 0.02 2h, 1300 ° C 75.23 8.31 5.17 3 1.0 1.25 4.25 4.2: 1 0.8 0.05 - -70.71 13.31 5.01 4 1.0 0.83 2.83 4.6: 1 1.21 0.03 - - 67.77 15.6 4.11 5 1.0 0.83 2.83 4.6: 1 1.21 0.05 - - 60.80 13.32 5.65 6 1.0 1.0 3.4 4.4: 1 1 0.03 0.007 CrO3-NaCrSi2O6 69.59 14.43 4.25 7 1.0 0.83 2.83 4.6: 1 1.21 0.05 - LiCrSi2O6 63.52 13.56 2.37 8 1.0 1.0 3.4 4.4: 1 1 0.04 - Wessalon S R 66.79 14.70 2.74 as SiO2 source 9 1.0 0.9 3.1 4.6: 1 1.11 0.04 - Wessalon S R 67.72 15.60 4.15 as SiO2 source 10 1.0 0.9 3.1 4.6: 1 1.11 0.04 - Wessalon S R 65.69 16.75 2.50 as SiO2 source Sn as SnO2 source Table 2: Relative color strength example Relative color strength /% 7 V1 100 V2 100 3 113 4 140 5 154 6 128 7 141 8 192 9 169 10 160

Claims (1)

Claims 1. Color bodies and pigments with a spherical structure of the general Formula x CaO. y SnO2. z SiO2 and additional coloring guest components, thereby characterized in that the molar ratio is less than 1.3 and the ratio of y x + z is greater than 3. y 2. color bodies and pigments according to claim 1, characterized in that that the molar ratio is greater than 2. x 3. Color bodies and pigments according to one of claims 1 and 2, characterized characterized in that the coloring guest components Cr (III) - and / or Au (ITI) - and / or La (III) compounds are and in amounts of 0.0S to 10 wt .-%, preferably 0.1 up to 5 wt. t, based on the calcium used. 4. A method for producing the color bodies and pigments according to a of claims 1 to 3, characterized in that for the production of the color bodies and pigments with a spherical structure, the starting and guest components used are homogeneous mixed, at temperatures between 5000C and 14000C annealed and finally be ground to the desired grain size. 5. The method according to claim 4, characterized in that the starting components Oxides and / or compounds which form oxides when annealed. 6. The method according to any one of claims 4 or 5, characterized in that that highly disperse silica is used as the SiO2 component. 7. Method according to one of claims 4 to 6, characterized in that which is used as CaO and SnO2 components, preferably white lime hydrate and Sn powder will. 8. The method according to claim 7, characterized in that the lime white hydrate and the Sn powder initially between 5000C and 1400 ° C, preferably between 8000C and 10000C, annealed in an oxidizing manner and then homogeneous with the other components mixed and annealed between 5000C and 14000C. 9. The method according to any one of claims 4 to 8, characterized in, that the coloring Cr (III) components in the form of Cr2O3 compounds and / or compounds of the type Me CrIII (Si206) with Me1 = Li, Na can be used. 10. Use of the color bodies and pigments according to Claims 1 up to 9 'for coloring enamels and ceramic glazes.