# US 5,344,488 A · Pigments > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,344,488 A - Document ID: US5344488A - Status: Granted - Kind: A - Application number: 07/979,860 - Filed: 1993-02-24 - Granted: 1994-09-06 - Earliest claimed: 1991-06-24 - Assignees: Merck Patent GmbH - Inventors: Peter Reynders; Hans D. Bruckner - Web page: https://patentgrep.com/patent/US5344488A ## CPC - 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} - C01P 2002/30: Three-dimensional structures - 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 2200/1054: the core consisting of a metal - 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 2200/301: Thickness of the core - C09C 2210/20: Optical properties in the UV-range - C09C 2220/10: Wet methods, e.g. co-precipitation - C09C 2220/103: comprising a drying or calcination step after applying each layer - 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 ## Abstract The application relates to pigments based on plate-like substrates which, if desired, are covered with one or more layers comprising metal oxides or metal oxide mixtures, zinc oxide being deposited on the surface of the substrates with the formation of a not entirely continuous layer. ## Claims ### Claim 1 Pigments based on plate-like substrates which, optionally, are covered with one or more layers comprising metal oxides or metal oxide mixtures, zinc oxide being deposited on the surface of the substrates with the formation of a discontinuous layer. ### Claim 2 (depends on 1) Pigment according to claim 1, in which the quotient from the sum of the areas of the discontinuous zinc oxide regions and the optionally coated substrate area below, which is defined as the degree of coverage with zinc oxide .theta., is between 0.02 and 0.95. ### Claim 3 (depends on 1) Pigment according to claim 1, in which the substrates are covered with an iron oxide layer or a mixed oxide layer containing iron oxide, on which zinc oxide has been deposited in the form of small needle-shaped crystallites. ### Claim 4 (depends on 1) Pigments according to claim 1, in which the substrates are covered with a titanium oxide layer or a mixed oxide layer containing titanium oxide, on which zinc oxide has been deposited in the form of small, essentially flat dots. ### Claim 5 Pigments based on plate-like substrates which, optionally, are covered with one or more layers comprising metal oxides or metal oxide mixtures, containing on the surface of the substrates a discontinuous zinc ferrite layer or a layer containing zinc ferrite. ### Claim 6 (depends on 1) Process for the preparation of pigments according to claim 1, characterised in that the plate-like substrates, which are covered with one or more layers comprising metal oxides or metal oxide mixtures, are suspended in water, in that an acid aqueous solution of zinc chloride or zinc sulfate is added to this suspension at a pH favourable for the deposition of zinc oxide, this pH being kept substantially constant by simultaneous addition of a base, and in that the product is separated off, washed, dried and, optionally, ignited. ### Claim 7 (depends on 3) Process for the preparation of pigments according to claim 3, characterised in that substrates covered with an iron oxide layer or a layer containing iron oxide are used and these substrates are suspended in water, an acid aqueous solution of chloride or zinc sulfide is added to this suspension at a pH favorable for the deposition of zinc oxide, this pH being kept substantially constant by simultaneous addition of a base, and the product is separated off, washed, and dried and not ignited or only ignited at low temperatures of less than 250.degree. C. ### Claim 8 (depends on 5) Process for the preparation of pigments according to claim 5, characterised in that substrates covered with an iron oxide layer or a layer containing iron oxide are used and these substrates are suspended in water, an acid aqueous solution of zinc chloride or zinc sulfate is added to the suspension at a pH favorable for the deposition of zinc oxide, this pH being kept substantially constant by simultaneous addition of a base, and the product is separated off, washed, dried, and ignited at temperatures of more than 650.degree. C. ### Claim 9 (depends on 6) Process for the preparation of pigments according to claim 6, characterised in that substrates covered with a titanium oxide layer or a layer containing titanium oxide are used. ### Claim 10 (depends on 1) A method of using pigments according to claim 1 which comprises adding said pigments to plastics, coatings or cosmetics.