MXPA99001112A - Interference pigments that have a tone too - Google Patents

Abstract

A multilayer interference pigment having a blue mass tone, consisting of a carrier material in the form of platelets and a coating which is formed from: (i) a first layer of clear, colorless metal oxide, is described. , of high refractive index, (ii) a second layer of colorless, transparent, low refractive metal oxide, and (iii) a third outer layer of cobalt aluminate, glass containing cobalt or cobalt oxide, it is also possible that the first and third layers are exchanged. The metal oxides of high refractive index used consist of titanium dioxide, zirconium dioxide or tin oxide. Low refractive metal oxide used consists of silicon dioxide or aluminum oxide

Description

INTERFERENCE PIGMENTS WHICH HAVE A BLUE MASS TONE Description of the invention The invention is concerned with multilayer interference pigments having a blue mass tone. The colored interference pigments are already known. They contain either dye additives or metal dye oxides, the latter also possibly forming the layer that produces the interference colors. The play of colors effected by this means is limited in nature. In particular, pigments with blue or bluish colors have not been available to date in a satisfactory shade. Furthermore, the selection of the desired colors is also restricted, since the dyes can greatly reduce the chemistry and thermostability of the interference pigments. US Pat. No. 3,951,679 discloses colored pigments based on mica which are coated with metal oxide layers and can additionally carry a colored coat of Prussian blue. The Prussian blue layer is formed by the reaction of an iron compound that has been deposited on the substrate with a water soluble hexacyanoferrate. This pigment has the disadvantage that Prussian blue decomposes at a temperature of 200 to 300 ° C. U.S. Patent 4,968,351 describes a pearlescent luster pigment which is colored by means of a REF. 29320 adsorbed dye, a colored lacquer that is applied to the dye layer in order to intensify the adsorption of the dye. A disadvantage of this pigment is that upon contact with the organic solvents the organic dye is separated from the interference pigment. In addition, the organic dye deteriorates the weathering stability of the pigment. U.S. Patent 5 169 442 discloses a blue-green pigment consisting of a substrate comprising mica coated with metal oxide and an upper layer formed of a mixed oxide of magnesium oxide, calcium oxide, cobalt oxide and dioxide. titanium. The mass tone of this pigment, however, is not pure blue. It is the object of the invention to provide interference pigments having a blue mass tone that possess the light stability, chemical stability and weathering stability of customary commercial interference pigments. This object is obtained according to the invention by multilayer interference pigments having a blue mass tone, consisting of a carrier material in the form of platelets and a coating which is formed from: (i) a first layer of a colorless, transparent, high refractive index metal oxide, (ii) a second layer of colorless transparent metal oxide of low refractive index, and (iii) a third outer layer of cobalt aluminate, glass containing cobalt or cobalt oxide This object is additionally obtained according to the invention by multilayer interference pigments having a blue mass tone, consisting of a carrier material in the form of platelets and a coating which is formed from: (i) a first cobalt aluminate layer, glass containing cobalt or cobalt oxide, (ii) a second layer of colorless metal oxide, transparent of low refractive index, and (iii) a third outer layer of a transparent, colorless metal oxide of high refractive index. This object is also obtained according to the invention by a process for preparing the pigments according to the invention, in which: the carrier material in the form of platelets is suspended in water and the suspension is heated to a temperature of 50 100 ° C, a water soluble metal compound is added at a pH that is suitable for hydrolysis, such that a metal oxide hydrate of high refractive index is precipitated on the suspended particles, the pH required for the Precipitation of the respective metal oxide hydrate is established and maintained constant by the simultaneous addition of acid or base, - Subsequently, the pH is adjusted with a base to a value of 4 to 10 and a water-soluble metal compound is added, such that a metal oxide hydrate of low refractive index is precipitated on the suspended particles. , the pH is kept constant by the simultaneous addition of acid or base, and - subsequently, the resulting product is washed, dried at a temperature of 60 to 180 ° C and calcined at a temperature of 500 to 1100 ° C, - then, the product is suspended in water and is coated at a pH of 3 to 10 with cobalt and aluminum oxide hydrate by addition and hydrolysis of the corresponding water-soluble metal compounds, the pH is kept constant by the simultaneous addition of a base , and - subsequently the product is washed, dried at a temperature of 60 to 180 ° C and calcined at a temperature of 500 to 1100 ° C. This object is also obtained according to the invention by a process for preparing the pigments according to the invention, in which: the carrier material in the form of platelets is suspended in water and the suspension is heated to a temperature of 50 100 ° C and is coated at a pH of 3 to 10 with cobalt and aluminum oxide hydrate by the addition and hydrolysis of the corresponding water-soluble metal compounds, the pH is kept constant by the simultaneous addition of base, - subsequently , the pH is adjusted with a base to a value of 4 to 10 and a water-soluble metal compound is added, in such a way that a metal oxide hydrate of low refractive index is precipitated on the suspended particles, the pH is maintains constant by the simultaneous addition of acid or base, and - then, a water-soluble metal compound is added to a pH appropriate for hydrolysis, such that a hydrate of metal oxide When the high refractive index is precipitated on the suspended particles, the pH required for the precipitate of the respective metal oxide hydrate is established and maintained constant by the simultaneous addition of acid or base, and - subsequently, the product is washed, dried at a temperature of 60 to 180 ° C and calcined at a temperature of 500 to 1100 ° C. The invention is also concerned with the use of the pigments according to the invention for pigment paints, printing inks, plastics, cosmetics and glazes or enamels for ceramics and glasses. For this purpose, they can be used as mixtures with the customary commercial pigments, examples are the inorganic and organic absorption pigments, the metal effect pigments and the LCP pigments. Suitable carrier materials for the pigments according to the invention are materials in the form of natural or synthetic platelets, which do not have an inherent color. Preferred carrier materials are phyllosilicates, metal oxide platelets and glass flakes and ceramic flakes. Particular preference is given to mica, talc, kaolin, synthetic mica and aluminum oxide and silicon dioxide platelets. The silicon dioxide platelets are produced according to the international patent application WO 93/08 237 in a continuous web by solidification and hydrolysis of a sodium silicate solution. The size of the carrier materials is not critical and can be matched to the particular proposed use. In general, the carrier materials in the form of platelets have a thickness between 0.05 and 5 μm, in particular between 0.2 and 2.0 μm. The extension in the other two dimensions is usually between 2 and 100 μm and in particular between 5 and 50 μm. The thickness of the individual layers of the pigment is essential for the optical properties of the pigment. For a pigment with intense interference colors, the thickness of the individual layers must be adapted to each other. In addition, it is possible, by means of an appropriate choice of layer thickness, obtain a particularly strong variation in color as a function of the viewing angle. This is obtained, for example, by the precipitation of a thick layer of Si02 (layer thickness >.;100 nm), to give pigments that have a pronounced angular dependence of the interference colors. The thickness of the individual layers of the pigments according to the invention are within the following ranges: Metal oxide of high refractive index: 70-110 nm Metal oxide of low refractive index: 60-110 nm Capa imparting color: 50-90 nm This gives rise, for example, to the following proportions for the individual constituents of a pigment according to the invention: 25-40% by weight of the carrier material 0.1-3% by weight of Sn02 20-40 % by weight of Ti02 (high refractive index metal oxide) 10-20% by weight Si02 (low refractive index metal oxide) 10-35% by weight of CoAl204. Tin dioxide serves only to induce rutile modification when titanium dioxide is used for the first layer. It is precipitated directly on the carrier material. This technique is described in more detail in U.S. Patent 4 867 794. The metal oxide layers are preferably applied by a wet chemical method, it is possible to employ wet chemical coating techniques developed for the preparation of pearlescent luster pigments.; techniques of this kind are described, for example, in DE 14 67 468, DE 19 59 988, DE 20 09 566, DE 22 14 545, DE 22 15 191, DE 22 44 298, DE 23 13 331, DE 25 22 572, DE 31 37 808, DE 31 37 809, DE 31 51 343, DE 31 51 354, DE 31 51 355, DE 32 11 602, DE 32 35 017 or elsewhere in additional patent documents and other publications . For the coating, the particles of the substrate are suspended in water and one or more hydrolysable metal salts are added to a pH which is suitable for hydrolysis and is chosen in such a way that the metal oxides and / or the Metals are precipitated directly on the particles without any instance of secondary precipitation.The pH is usually kept constant by the simultaneous dosed addition of a base.The coating can also be carried out, furthermore, by gas-phase coating in a bed reactor For example, it is possible, for example, to apply the processes proposed in EP 0 045 851 and EP 0 106 235 to prepare pearlescent luster pigments.As a metal oxide with a high refractive index, use is made of titanium dioxide, dioxide zirconium oxide or tin oxide, preference is given to titanium dioxide.As the metal oxide of low refractive index, it is used dioxide silicon or aluminum oxide, preference is given to silicon dioxide. For the application of titanium dioxide layers, preference is given to the technique described in U.S. Patent 3 553 001. An aqueous titanium salt solution is added slowly to a suspension, heated to a temperature of about 50-100 °. C, especially 70-80 ° C, of the material to be coated and a substantially constant pH of about 0.5-5, in particular about 1.5-2.5, is maintained by the simultaneous dosed addition of a base, for example, aqueous solution of ammonia or aqueous solution of alkali metal hydroxide. As soon as the desired layer thickness of the Ti02 precipitation has been obtained, the addition of the titanium salt solution and the base is stopped. This process, also called the titration process, is notable for the fact that it avoids an excess of titanium salt. This is obtained by feeding the hydrolysis only the amount per unit time that is necessary for the uniform coating with the hydrated Ti02 and which can be received per unit time by the available surface area of the particles to be coated. There is therefore no production of titanium dioxide particles hydrated or precipitated on the surface to be coated. For the application of silicon dioxide layers, the following process will be used: A solution of sodium silicate is dosed in a suspension, heated to a temperature of 50-100 ° C, especially 70-80 ° C, of the material to be coated. The pH is kept constant at a value of 4 to 10, preferably 6.5 to 8.5, by the simultaneous addition of 10% hydrochloric acid. Agitation is carried out for an additional 30 minutes immediately after the addition of silicate solution. The precipitation of aluminum oxide hydrate on materials in the form of platelets is known from US Pat. No. 4,084,983. The material is suspended in water and this suspension is heated judiciously at relatively high temperatures, for example, between 40 and 95 °. C. Then, an aqueous acidic solution of a water soluble aluminum salt, for example, aluminum chloride, aluminum nitrate, potassium aluminum sulfate or aluminum sulfate or an alkaline aqueous solution of an aluminate, for example, sodium aluminate or Potassium aluminate is added to the suspension. The concentration of Al ions in the current saline solution is between 0.1 and 5 moles / liter. At the same time, alkali or acid is added in order to establish a pH of between 3 and 10, preferably between 4 and 9. A suitable alkali comprises, in particular, alkali metal hydroxides and ammonium hydroxides, preferably aqueous NaOH. or NH3 gas. In the case of the addition of acid, preference is given to HCl, H2SO4 or HN03. The addition of the alkali or acid is regulated in such a way that the pH of the suspension remains as constant as possible during the precipitation. The precipitation of cobalt oxide hydrate is described in more detail in EP 0 342 533. It is carried out at a pH of 4 to 9. Since the precipitation conditions of the cobalt oxide hydrate and the oxide hydrate of aluminum are virtually identical, co-precipitation of both oxide hydrates is possible.

If cobalt oxide is used as the layer imparting color, then the cobalt oxide hydrate is likewise precipitated by the process described above. If a glass containing cobalt is used as the layer imparting color, the procedure is as follows: Cobalt oxide hydrate and silicon oxide hydrate are co-precipitated as a mixed precipitate on the carrier material, as a first or third layer, under the conditions summarized above. In this case, the glass structure is formed in the course of the product calcination. The tungsten bronzes of the general formula MxW03 can also be used as the layer imparting color. The alkali metal tungstates deposited on the carrier material are subsequently reduced with hydrogen or other appropriate reducing agent to such an extent that a compound of the formula M0.3WO3 is formed. These tungstates are of an intense blue-violet color. It is additionally possible to subject the finished pigment to a post-coating or post-treatment process which additionally increases light stability, weathering stability and chemical stability or which facilitates handling of the pigment, especially its incorporation into different media. Appropriate post-coating and post-treatment processes are those described for example in DE-C 22 15 191, DE-A 31 51 354, DE-A 32 35 017 or DE-A 33 34 598. The examples that they continue to propose to illustrate the invention without restricting it.

Example 1 100 g of mica (10-60 μm) are suspended in 2 liters of deionized water and the suspension is heated to a temperature of 75 ° C with stirring. A pH of 1.8 is established with diluted HCl with a solution of 3.2 g of SnCl4"5H20 and 10 ml of 37% HCl in 50 ml of deionized water is dosed at a rate of 2 ml / minute. kept constant with 32% NaOH After 30 minutes of stirring, 450 ml of TiCl4 solution (400 g / liter) are dosed in a similar way at a rate of 2 ml / minute.The pH is kept constant by the simultaneous addition of 32% NaOH The pH is subsequently adjusted to 7.0 with NaOH and the mixture is stirred for 30 minutes Now, a solution of sodium silicate (135 g of sodium silicate, 27% relative to SiO 2, diluted with 135 g of water) is dosed at a rate of 2 ml / minute, the pH is kept constant by the addition of 10% HCl After the end of the addition, stirring is carried out for 10 minutes at a temperature of 75 C. After this, the suspension is filtered with suction and the solid product is l salt-free shelf with deionized water and drying at a temperature of 110 ° C. After the subsequent calcination, at a temperature of 800 ° C for 30 minutes, the product is sieved and resuspended in 2 liters of deionized water. The pH is adjusted to 7.5 with NaOH and kept constant during the addition of a solution of 132 g of Co (N03) 2'6H-0 and 218 g of A1C13'6H20 in 1200 ml of deionized water, added at a rate of 2 ml / minute The suspension is subsequently stirred for 30 minutes and filtered with suction and the solid product is washed free of salt with deionized water and dried at a temperature of 110 ° C. The dried product is subsequently calcined at a temperature of 1000 ° C for 30 minutes and after cooling it is sieved. 290 g of gold interference pigment having a blue mass tone is obtained. According to the X-ray structural analysis, the pigment according to the invention consists of mica Ti02 in the modification of rutile and CoAl204 (spinel). The photoactivity of the pigments is within the range of commercial, customary Ti02 pigments. The results of short-term weathering tests in the water immersion test (1-layer system, conventional coating material) are very good. Gray scale values [DIN 54001; ISO Standard 105 Section A02]: 16 h / 66 ° C = 5-4 and 20 H / 80 ° C = 4-5.

Example 2 100 g of Si02 flakes (prepared according to WO 93/08 237) are suspended in 2 liters of deionized water and the suspension is heated to a temperature of 75 ° C. A solution consisting of 12 g of SnCl4-5H20 and 40 ml of 37% HCl in 370 ml of water at a pH of 1.8 is dosed at a rate of 2 ml / minute. During the addition, the pH is kept constant with 32% NaOH solution. After the end of the addition of the SnCl 4 solution, stirring is carried out for 10 minutes and then 620 ml of TiCl 4 solution (410 g of TiCl 4 / liter of water) are dosed at a rate of 2 ml / minute. During the coverage operation, the pH is kept constant by the addition of 32% NaOH solution. After 30 minutes, the pH is adjusted to 7.0 with NaOH and a solution of sodium silicate (190 g of sodium silicate diluted with 190 g of water) is dosed at a rate of 2 ml / minute, the pH is kept constant by the simultaneous addition of 10% HCl. After the end of the addition, the stirring is continued at a temperature of 75 ° C for 15 minutes. The pigment is filtered, washed free of salt, dried at a temperature of 60 to 180 ° C and finally calcined at a temperature of 800 ° C for 60 minutes. After subsequent sieving, the product is suspended again in 1250 ml of deionized water. After a pH of 7.5 has been established, a solution of 100 g of Co (N03) 2 and 164 g of A1C13-6H20 in 900 ml of water is added at a rate of 2 ml / minute, the pH is kept constant with NaOH The mixture is subsequently stirred for 30 minutes, filtered, washed and the solid product washed free of salt, dried at a temperature of 60 to 180 ° C and calcined at a temperature of 1000 ° C. A gold interference pigment having a blue mass tone is obtained.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is the conventional one for the manufacture of the objects or products to which it refers. Having described the invention as above, property is claimed as contained in the following:

Claims (16)

1. Claims 1. A multilayer interference pigment having a blue mass tone, consisting of a carrier material in the form of platelets and a coating that is formed from: (i) a first layer of a colorless metal oxide, transparent, with high refractive index, (ii) a second layer of transparent metal oxide with a low refractive index, and (iii) a third external layer of cobalt aluminate, glass containing cobalt or cobalt oxide.
2. 2. A multilayer interference pigment having a blue mass tone, consisting of a carrier material in the form of platelets and a coating which is formed from: (i) a first layer of cobalt aluminate, glass that contains cobalt or cobalt oxide, (ii) a second transparent, low-refraction, colorless metal oxide layer, and (iii) a third outer layer of a transparent, high-refraction transparent metal oxide.
3. 3. The interference pigments according to claim 1 or 2, characterized in that the carrier material in the form of platelets comprises natural or synthetic mica, other phyllosilicates, glass plates, aluminum oxide platelets, or silicon dioxide platelets.
4. The interference pigments according to one of claims 1 to 3, characterized in that the transparent, high-refractive metal oxide is titanium oxide, zirconium oxide or tin oxide.
5. The interference pigments according to one of claims 1 to 4, characterized in that the transparent, colorless, low-refractive metal oxide is silicon dioxide or aluminum oxide.
6. 6. A process for the preparation of the pigments according to claim 1, characterized in that: the carrier material in the form of platelets is suspended in water and the suspension is heated to a temperature of 50 to 100 ° C, a compound of Water-soluble metal is added at a pH which is suitable for hydrolysis, such that a metal oxide hydrate of high refractive index is precipitated on the suspended particles, the pH required for the precipitation of the respective hydrate of oxide of metal is established and maintained constant by the simultaneous addition of acid or base, - subsequently, the pH is adjusted with a base to a value of 4 to 10 and a water-soluble metal compound is added, such that a hydrate of Low-refractive metal oxide is precipitated on the suspended particles, the pH is kept constant by the simultaneous addition of acid or base, and - subsequently, the The resulting product is washed, dried at a temperature of 60 to 180 ° C and calcined at a temperature of 500 to 1100 ° C, - then, the product is suspended in water and is coated at a pH of 3 to 10 with cobalt and hydrate of aluminum oxide by addition and hydrolysis of the corresponding water soluble metal compounds, the pH is kept constant by the simultaneous addition of a base, and - subsequently the product is washed, dried at a temperature of 60 to 180 ° C and calcined at a temperature of 500 to 1100 ° C.
7. The process for the preparation of pigments according to claim 2, characterized in that: - the carrier material in the form of platelets is suspended in water and the suspension is heated to a temperature of 50 to 100 ° C and is coated to a pH from 3 to 10 with cobalt and aluminum oxide hydrate by the addition and hydrolysis of the corresponding water-soluble metal compounds, the pH is kept constant by the simultaneous addition of base, - - Subsequently, the pH is adjusted with a base to a value of 4 to 10 and a water-soluble metal compound is added, such that a metal oxide hydrate of low refractive index is precipitated on the suspended particles, the pH is kept constant by the simultaneous addition of acid or base, and - then, a water-soluble metal compound is added to a pH appropriate for hydrolysis, such that a metal oxide hydrate of high refractive index is precipitated on the suspended particles, the pH required for the precipitate of the respective metal oxide hydrate is established and maintained constant by the simultaneous addition of acid or base, and - subsequently, the product is washed, dried at a temperature of 60 to 180 ° C and calcined at a temperature of 500 to 1100 ° C. C.
8. The process according to claim 6 or 7, characterized in that the carrier material in the form of platelets comprises natural or synthetic mica, other phyllosilicates, glass flakes, aluminum oxide platelets or silicon dioxide platelets.
9. The process according to one of claims 6 to 8, characterized in that the transparent, high-refraction, colorless metal oxide is titanium dioxide, zirconium dioxide or tin oxide.
10. The process according to one of claims 6 to 9, characterized in that the metal oxide, colorless, transparent, of low refractive index is silicon dioxide or aluminum oxide.
11. The process according to one of claims 6 to 9, characterized in that after the intermediate drying of the material to be coated, the metal solids are applied by CVD (chemical vapor deposition) in a fluidized bed reactor.
12. 12. The use of the pigments according to claim 1 6 2, for pigment paints, printing inks, plastics, cosmetics and glazes or enamels for ceramics and glasses.
13. The use according to claim 12, characterized in that the pigments are used as mixtures with the customary commercial pigments.
14. 14. The use of pigments according to claim 1 or 2 for laser marking of plastics.
15. 15. Paints, printing inks, plastics, cosmetics, ceramics and glasses which have been pigmented with the pigment according to claim 1 or 2.
16. 16. Markable plastics by laser comprising pigments according to claim 1 or 2.