# US 7,611,574 B2 · Interference pigment with a high covering power

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- Number: US 7,611,574 B2
- Document ID: US7611574B2
- Status: Granted
- Kind: B2
- Application number: 10/555,592
- Filed: 2004-05-05
- Published: 2007-02-08
- Granted: 2009-11-03
- Earliest claimed: 2003-05-08
- Assignees: Merck Patent GmbH
- Inventors: Helge Kniess; Gerhard Pfaff; Klaus Bernhardt
- Web page: https://patentgrep.com/patent/US7611574B2

## CPC

- C09C 1/0039: {consisting of at least one coloured inorganic material}
- C09C 1/0015: {Pigments exhibiting interference colours, e.g. transparent platelets of appropriate thinness or flaky substrates, e.g. mica, bearing appropriate thin transparent coatings}
- C09C 1/0021: {comprising a core coated with only one layer having a high or low refractive index}
- C09C 1/0066: {consisting of at least one coloured inorganic material}
- C01P 2004/61: Micrometer sized, i.e. from 1-100 micrometer
- C01P 2004/84: one phase coated with the other
- C09C 2200/1004: the core comprising at least one inorganic oxide, e.g. Al2O3, TiO2 or SiO2
- C09C 2200/102: the core consisting of glass or silicate material like mica or clays, e.g. kaolin
- C09C 2200/1062: the core consisting of an organic compound, e.g. Liquid Crystal Polymers [LCP], Polymers or natural pearl essence
- C09C 2200/1087: the core consisting of bismuth oxychloride, magnesium fluoride, nitrides, carbides, borides, lead carbonate, barium or calcium sulfate, zinc sulphide, molybdenum disulphide or graphite
- C09C 2200/205: of coloured inorganic materials
- C09C 2220/106: comprising only a drying or calcination step of the finally coated pigment
- Y10T 428/2991: Coated
- Y10T 428/2993: Silicic or refractory material containing [e.g., tungsten oxide, glass, cement, etc.]
- C09C: TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES (treatment of materials specially adapted to enhance their filling properties in mortars, concrete or artificial stone C04B14/00, C04B18/00, C04B20/00); PREPARATION OF CARBON BLACK {; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS}
- C01P: INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

The invention relates to an interference pigment with a high covering power, comprising at least one FeTiO3-containing layer, which is applied to a lamellar inorganic substrate and whose thickness and absorbing power can be precisely set. The invention also relates to a method for producing this interference pigment and to the use thereof.

## Claims

### Claim 1

A process for producing an interference pigment, comprising a flake-form inorganic substrate and at least one FeTiO3-containing layer thereon, where the FeTiO3 is present in a proportion of 8-100% by weight, based on the total weight of the layer, and is homogeneously distributed in the layer, and at least one further layer of metal oxides, metal oxide hydrates, MgF2 or BiOCl, said process comprising the following steps:
a flake-form inorganic substrate is suspended in water,
a water-soluble inorganic metal compound is added, and a pH at which a corresponding metal oxide hydrate, MgF2 or BiOCl is deposited on the substrate surface is set and kept constant,
a water-soluble inorganic titanium compound and a water-soluble inorganic iron compound in a molar ratio of 1:0.05 to 1:1, based on the oxides TiO2 and Fe2O3, are added simultaneously to the suspension at a temperature of 50 to 100° C. and a pH kept constant in the range from 1.4 to 4.0, during which the corresponding oxide hydrates of TiO2 and Fe2O3 are deposited on the substrate surface as a mixture,
the resultant coated substrate is separated off, optionally washed and dried, and
thermally treated at temperatures in the range from 500° C. to 1200° C. under reducing conditions.

### Claim 2 (depends on 1)

A process according to claim 1, where the FeTiO3 is present in a proportion of 15-99% by weight.

### Claim 3 (depends on 1)

A process according to claim 1, where the FeTiO3 is present in a proportion of 54-99% by weight.

### Claim 4 (depends on 1)

A process according to claim 1, where the flake-form inorganic substrate consists of natural or synthetic mica, talc, kaolin, glass flakes, SiO2 or TiO2 flakes, flake-form iron oxide or aluminium oxide, graphite flakes, BiOCl, flake-form holographic pigments or liquid crystal polymers (LCPs).

### Claim 5 (depends on 1)

A process according to claim 1, said process further comprising depositing on the FeTiO3 containing layer at least one layer package consisting essentially of a layer of non-absorbent material having a refractive index of n≦1.8 and a layer of non-absorbent material having a refractive index of n>1.8.

### Claim 6 (depends on 5)

A process according to claim 5, where the non-absorbent material having a refractive index of n≦1.8 consists essentially of SiO2, SiO(OH)2, Al2O3, AlO(OH), B2O3 or mixtures thereof, or of MgF2.

### Claim 7 (depends on 5)

A process according to claim 5, where the non-absorbent material having a refractive index of n>1.8 consists essentially of TiO2, ZrO2, ZnO, SnO2 or mixtures thereof, or of BiOCl.

### Claim 8 (depends on 1)

A process according to claim 1, where the FeTiO3-containing layer additionally comprises one or more further metal oxides in an amount of ≦20% by weight, based on the weight of the layer.

### Claim 9 (depends on 8)

A process according to claim 8, where the further metal oxide is selected from the group consisting of Al2O3, Ce2O3, B2O3, ZrO2 and SnO2 or mixtures thereof.

### Claim 10 (depends on 5)

A process according to claim 5, in which a further FeTiO3-containing layer is applied.