Compositions: coating or plastic – Materials or ingredients – Pigment – filler – or aggregate compositions – e.g. – stone,...
Patent
1997-09-02
1999-08-03
Green, Anthony
Compositions: coating or plastic
Materials or ingredients
Pigment, filler, or aggregate compositions, e.g., stone,...
106 3165, 106493, 106499, 106504, 428403, 428469, 428472, 523200, 524441, C09C 164
Patent
active
059319968
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention concerns coloured aluminium pigments, a process for the production thereof and use thereof.
Aluminium pigments are used widely in coatings as special-effect pigments. The term special-effect pigments is used to denote pigments which have a directed reflection at oriented, metallic or highly light-refractive particles of a predominantly flat configuration (German Standard DIN 55944). They are always of plate-like or flake-like configuration and have very large particle diameters compared with dye pigments. Their optical properties are determined by reflection and interference. Depending on transparency, absorption, thickness, singlelayer or multi-layer structure, the special-effect pigments exhibit a metallic shine, a pearl shine, interference or interference reflection. The main area of use are in the cosmetics and automobile sector, and in addition in colouring plastic materials, paints, leather coatings, in the printing industry and in the ceramic industry. (For a comprehensive representation of the technical background, see W. Ostertag, Nachr. Chem. Techn. Lab. 1994, 9, 849.).
The special-effect pigments which are most frequently used are aluminium flakes and coated mica flakes, wherein aluminium pigments exhibit a typical metal shine and coated mica flakes exhibit a typical pearl shine.
In recent years the need for coloured special-effect pigments has increased greatly. Therefore for example oxide-covered copper and brass flakes, substrates which are coated with transition metal oxides, such as muscovite, phlogopite or glass, guanine single-crystals (fish silver), BiOCl-single crystals, flake-form haematite single-crystals, flake-form phthalocyanines or crushed thin multi-layer films with a Fabry-Perot-structure are used as special-effect pigments.
In order to achieve colour effects inter alia aluminium pigments are also mixed with transparent dye pigments. The colouristic options with that method are however limited insofar as it is not possible in that way to achieve interference effects and therefore the pigments do not have a pearl shine. However, because of the transparency, interference pigments with a pearl shine, which are mostly based on coated mica flakes, have a poorer covering capability than aluminium pigments. Attempts have therefore been made to produce pigments with the good covering capability of aluminium flakes and the colouristic options of interference pigments, by colouring aluminium pigments.
U.S. Pat. No. 4,328,042 and EP-A-0 033 457 describe the production of gold-coloured aluminium pigments by the deposition of iron oxide, wherein iron pentacarbonyl is oxidised with oxygen in a fluidised bed of the aluminium flakes, the bed being produced by fluidisation with inert gas. The disadvantage of that procedure is the very high level of technological expenditure.
U.S. Pat. No. 5,037,475 describes the production of aluminium pigments which are coloured by fixing colour pigments on the metal surface. The colour pigments are fixed by way of carboxyl group-bearing polymers. A protective layer can be applied by polymerisation, to improve the adhesion. However the pigments produced in that way have only a low level of colour intensity.
WO 91/04293 (PCT/US90/05236) describes the colouring of aluminium pigments by fixing poly -coated colour pigments from aqueous solvents on the metal surfaces by way of electrostatic forces. In that situation the coating result depends in a complex manner on the type of aluminium pigment, the nature of the polymer coating on the colour pigments, the solvent composition and the pH-value.
EP-A-0 328 906 discloses titanium dioxide-coated metal pigments, inter alia also aluminium pigments, which are produced by hydrolysis of an organic titanate ester compound, for example tetraisopropoxytitanium, in the presence of the metal flakes which are suspended in an organic medium, at pH of from 4 to 8. Various colour shadescan be achieved with that process by varying the thickness of the titanium dioxide layer. Maintaining speci
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Mebarek Denise
Reisser Wolfgang
Eckart-Werke Standard
Green Anthony
Lucas James A.
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