Pigments based on silica and iron oxide and method of production thereof

 

The invention is intended for chemical and ceramic industry and can be used to obtain enamels, glass, ceramics, cements, plastics, laminates, inks, rubbers, and also to furnish their surfaces. Highly dispersed silica dust obtained by condensation of gases released during the production of silicon metal and/or alloys thereof, is mixed with iron oxide. The content of the fine silica dust 70-98 wt. per cent, of oxide of iron 2-30 wt.%. The mixture aglomerados, calcined at 800-1300^oWith 1-24 hours Burnt pigment mix, crushed, finally stirred and control color. The finished pigment is metered and Packed. After agglomerating can additionally carry out spraying and pre-firing and subsequent cooling. Pigments are red-orange hue. Porcelain containing 5% of the pigments according to the invention have the following chromaticity coordinates Hunter-LAB: L=36-46; as=10-18; b=7-11. The resulting pigments have low cost and high quality. 5 C. and 16 h. p. F.-ly, 1 Il.

The technical field to which the invention relates the Invention relates to the production of pigments. More precisely onaylanmistir and in particular, in the production of ceramic materials and products. Component of these pigments, representing silica, obtained from superfine microchromosomes dust (quartz dust) or of fine silica dust, which is the most distinctive feature of the invention.

The prior art Natural pigments based on silica and iron has been known since ancient times because of their chromophore properties. They are widely used in ceramic production for coloring the masses and create a color in the range - pale yellow, brownish-yellow, reddish-yellow - brown - orange - reddish when introducing them in large quantities from 2 to 12 wt.%. However, they are essentially devoid of uniformity due to the variation of physico-chemical properties of the coatings.

There were several attempts in the quest to reproduce the characteristic properties of natural dyes of this type, but these efforts have always encountered the limitation caused by the necessity to obtain products of good quality at competitive cost relative to market prices established for natural products.

In our previous projects have been various attempts Voprosy Fe₂O₃it was from 5 to 15 wt.%, and the gel may be subjected to drying, roasting and grinding to obtain a product of good quality.

In U.S. patent 3005724 (1961) source product is colloidal silica as a source of silica and a source of iron oxide is preferably ferric sulfate, you get a suspension, which is subjected to gelation by adding alkaline solution. This gel is dried and subjected to calcination at temperatures from 900 to 1400^oWith, and then it is crushed to obtain a pigment.

On the other hand, there are patents in which to improve the properties of synthetic pigments based on iron oxide using a thin silica dust. In these cases, the silica is used in small quantities from 0.25 to 10%, and it is used to improve fluidity and coloring properties of pigments compared with those obtained by artificial iron oxides.

In U.S. patent 4221607 and 4229635 described methods for producing iron oxide of this type, starting from a solution of melanterite as a source of iron oxide, to which is added a small amount of silica (0.25 to 10% wt.) with the aim of obtaining zeleznicnych pigments with improved with the yoke and get iron pigment, which "behaves" better in the firing process, whereas in the method according to U.S. patent 4229635 iron type after the firing process and during the process of leaching of the dye, before final drying and grinding, which allows to obtain a pigment with improved fluidity.

Were not found references to use superfine melhoramentos dust for the production of pigments based on silica and iron oxide.

Brief description of the invention the present invention is to obtain inorganic pigments based on silica and iron oxide system Fe₂About₃and SiO₂using superfine microclimatology dust or fine silica dust as a source of silica, and the design method for industrial production of this pigment. The resulting pigments can have a red-orange tint, mainly when using them in the manufacture of ceramic products with low porosity, such as porcelain ceramic products. They represent a competitive alternative from the point of view of the quality and prices of natural materials, such as ceramics Thiviers used at the present time. The product comes with a C is a direct dispersion, that eliminates the need for grinding.

Detailed description of the invention, the Dyes according to the invention consist essentially of mixtures of silicon dioxide (silica) present in amounts of from 70 to 98 wt.%, and iron oxide present in different amounts in relation to a mixture of SiO₂and Fe₂About₃.

The present invention is used superfine microcompany dust or fine silica dust as a source of silicon dioxide. This dust is mainly produced as a by-product in the condensation of gases released during the process of obtaining silicon metal during arc melting) and alloys of silicon and other metals. Specified product has a high silica content in it (more than 90% of it is SiO₂and extremely small particle size (about 100 nm).

As a source of iron oxide can be used red and/or yellow iron oxide (natural and/or artificially derived) or salts and/or complexes of iron, which can be subjected to oxidation and/or decomposition during the firing process with the aim of obtaining iron oxide.

Small amounts of additives can be added is Tate dyes are pigments red-orange color, which can be used for dyeing all types of materials, preferably ceramic materials and, in particular, ceramic masses, which are ceramic materials with low porosity type porcelain ceramic products.

Depending on the composition, source of iron oxide, conditions subsequent roasting and processing, which is exposed to the dye, can be obtained with a wide range of colors within the red-orange tones.

In essence, the silica creates a layer of protective coating for iron oxide particles, protecting it from external damaging factors, such as temperature, atmosphere and/or destruction of other substances. This protective layer ensures that the iron oxide thus treated, will remain more stable during its use in ceramic mixtures, which are exposed to high temperatures in the production process.

These dyes are based on silica and iron are obtained by firing mixtures of starting materials at high temperatures with the formation of the pigment with the structure of tridymite [O₂Si] and/or cristobalite [SiO₂, modification of quartz, stable at temperatures >1470^oS] , which includes the oxide jelly is this the result is a stable or other structure depending on the firing conditions and present impurities.

Various mixtures of the starting materials can be prepared using dry or wet processes. In the dry process, the mixture of starting materials is obtained in the mill or mixer. The resulting mixture in a possible variant, but not necessarily be subjected to granulation in order to facilitate working with this mixture (meaning transport, dosing. . . ). In the wet process, a slurry of starting materials in water is prepared by grinding and dispersing the mixture is dried during the spraying process, in which receive the agglomerated material suitable for further processing.

These mixtures as raw materials, to a greater or lesser degree whether, in a possible variant, but may not necessarily subjected to preliminary drying, and then subjected to calcination (heat treatment at high temperature, which will have different physico-chemical transformations, which provide conversion material in its final state). The specified firing can be performed in furnaces of various types at temperatures of components from 800 to 1300^oWith, depending on the properties of silica, a source of iron oxide and additives used.

After baking, the product undergoes surgery to reduce the size of the particles in order to obtain a more uniform color. This operation is preferably performed in the plant for dry grinding with dynamic partitioning, which allows you to ensure that the size of more than 99% of particles are less than 40 microns.

EXAMPLES Example 1 87 kg superfine microchromosomes dust and 13 kg of red iron oxide, obtained by artificial means, is subjected to grinding in the mill of silica balls for 4 hours with 50 liters of water. The resulting suspension is dried, and the obtained granules are fired at a maximum temperature of 1,050^oWith over three hours. Get product red, which is ground in a mill with aluminum balls in dry conditions as long as the size of the 99% of the particles will not be less than 40 microns. This dye added to the standard mixture for porcelain ceramic in an amount of 5 wt.%, call ersey microchromosomes dust and 72 kg of red iron oxide, obtained by artificial means, is subjected to granulation in the intensive granulation with 80 liters of water. The obtained granulate is dried and subjected to calcination at 1025^oWith over 6 hours at this maximum temperature. Get the product of a reddish color, which is crushed as in example 1. The obtained chromaticity coordinates are L=40,3; a=15,0, and b=7,3.

Example 3 94 kg superfine microchromosomes dust and 6 kg of red iron oxide, obtained by artificial means, are treated the same way as in example 1. The obtained chromaticity coordinates are L=43,5; a=17,2 and b=8,5.

Example 4 In the mill silica balls of preparing a suspension of 65,8 kg superfine microchromosomes dust, 34.2 kg of ferrous sulfate (FeSO₄7H₂O) and 75.0 kg of water. The grinding takes 4 hours. The suspension is dried and receive a granulate, which is pre-calcined to decompose the sulphates and oxidation of iron oxide, and the mixture is then subjected to firing at a temperature of 1100^oC. coordinates of color who get fired for objects made with the amount of dye that is equal to 5% wt., are L=43,0; a=16,6 and b=10,5.

The drawing shows a block diagram used is alchemie (grinding)
4. Agglomeration
5. Precalcination
6. Firing
7. Cooling
8. Homogenization (mixing)
9. Dry grinding
10. Homogenization
11. Filling in mexcio

Claims

1. Pigment-based silica and iron oxide, wherein the silica component SiO₂obtained from superfine microchromosomes dust or fine silica dust and has a silica content of 70 to 98 wt.%, the content of iron oxide is in the range of 2 to 30 wt.%.

2. The pigment under item 1, characterized in that it is used, separately or in mixtures with other materials as a component in the composition of enamel, glass, ceramic materials, cements, plastics, laminates, printing ink and rubber.

3. The pigment according to any one of paragraphs.1 and 2, characterized in that it is used individually or in mixtures with other materials for finishing the surfaces of enamel, glass, ceramic materials, cements, plastics, laminates, printing ink and rubber.

4. A method of obtaining a pigment under item 1, characterized in that a) mix the raw materials; (b) aglomerados the mixture of starting materials, obtained in the previous step; (C) rc="https://img.russianpatents.com/chr/176.gif">From within 1 to 24 h;

d) mix the pigment obtained in the previous operation of the firing;

e) reduce the particle size of the resulting mixture of pigment;

f) finally mix the pigment with the control of the chromaticity coordinates of the obtained pigment; (g) is metered and pack the finished pigment.

5. The method according to p. 4, characterized in that stage a) and/or (b) execute in a dry mode.

6. The method according to p. 4, characterized in that stage a) and/or (b) perform in wet mode.

7. The method according to any of paragraphs.4 and 5, characterized in that the mixture of stage a) is obtained by grinding.

8. The method according to any of paragraphs.4 and 5, characterized in that the mixture of stage a) is obtained by dispersion, preferably in water.

9. The method according to any of paragraphs.4, 5 and 7, characterized in that the agglomeration stage b) contains granulation.

10. The method according to any of paragraphs.4, 6 and 8, characterized in that the agglomeration stage b) contains drying by spraying.

11. The method according to any of paragraphs.4-10, characterized in that, before stage (C) carry out the operation of pre-firing.

12. The method according to any of paragraphs.4-11, wherein after stage C) before homogenization of the resulting pigment perform cooling operation.

13. Way, struggling hard to keep myself those what he received in accordance with the method according to PP.4-13.

15. The pigment under item 14, characterized in that it is used individually or in mixtures with other materials as a component in the composition of enamel, glass, ceramic materials, cements, plastics, laminates, printing ink and rubber.

16. The pigment according to any one of paragraphs.14 and 15, characterized in that it is used individually or in mixtures with other materials for finishing the surfaces of enamel, glass, ceramic materials, cements, plastics, laminates, printing ink and rubber.

17. The use of fine silica dust as a source of SiO₂in the manufacture of inorganic pigments and/or dyes.

18. Application under item 17, wherein the source of silica was prepared by condensation of gases released during the production of silicon metal and/or alloys thereof.

19. The ceramic is characterized in that it includes in its membership the pigments according to any one of paragraphs.1-3, 14-16.

20. Ceramic under item 19, characterized in that it is porcelain ceramic.

21. Ceramic on p. 20, characterized in that it has the chromaticity coordinates Hunter-LAB the following is