Aluminum phosphate or polyphosphate particles for use as pigments in paints and method of making same

Aluminum phosphate or polyphosphate particles for use as pigments in paints and method of making same

NOVELTY – An amorphous aluminum phosphate or polyphosphate (I) comprises a bulk density of 1.95 – 2.3 g/cm3 and a phosphorus to aluminum mole ratio of greater than 0.8. USE – In paint; as an ingredient in a varnish, printing ink and plastic; and as a white pigment e.g. for adding to a mixture containing titanium dioxide (claimed). ADVANTAGE – The method results in non-crystalline aluminum phosphate having unique physical and chemical characteristics i.e. nano-sized and low-density particles, that form closed voids after drying and result in hollow particles that are capable of scattering light, and exhibit non-stoichiometry. The aluminum phosphate particles (at least 10%) resist coalescence upon drying. Due to the non-stoichiometry, various formulations of the aluminum phosphate can be prepared by changing the fabrication process and thus final product composition, and is suitable for inclusion in various pigment formulations. This also provides easy swelling control, which is beneficial for its performance. The formation of aluminum phosphate does not require extensive drying step of the phosphate, which increases the complexity and cost of manufacturing. As the preparation is carried out at controlled pH levels, it is nearly neutral and avoids the environmental and toxicological problems and forms a zero-effluent product. The aluminum phosphate provide various benefits when included in paint such as; development of opacity or whiteness during the fabrication or application process of the paint; extensive distribution in the film with intimate association with resin and inorganic paint fillers to form clusters that serve as sites for extensive void formation after drying of the paint; synergism with titanium dioxide in respect of hiding power due to the void formation and cost reduction by replacement of titanium dioxide; stability towards settling, which allows uniform paint dispersion; compatibility with latex particles by mechanisms of capillary adhesion, followed by inter-cluster mediated electrostatic adhesion to form bicontinuous network; and compatibility towards the other particulate solids of paint fillers. DETAILED DESCRIPTION – INDEPENDENT CLAIMS are included for the following: (1) an amorphous aluminum phosphate or polyphosphate-based pigment product (I’) prepared by: contacting phosphoric acid with aluminum sulfate and an alkaline solution, substantially in the absence of organic solvent; and optionally calcining the aluminum phosphate based product at an elevated temperature; and (2) making a white pigment comprising amorphous aluminum phosphate or polyphosphate involving: combining phosphoric acid, aluminum sulfate and sodium hydroxide into a suspension; filtering and washing the suspension into a cake; forming dispersion of the washed cake; drying the cake; polymerizing the dry product; and micronizing the product.

Main Application Field

A60 (Additives and Compounding Agents If the usage is very restricted it may be classified under the individual polymer or process involved.); E33 (Compounds of Be, Mg, Ca, Sr, Ba, Ra, Sc, Y, La, Ac, Al, lanthanides (Rare-earths), Th.); E32 (Compounds of Ti, Zr, Hf, Cu, Ag, Au, Zn, Cd, Hg, Ga, In, Te, Ge, Sn, Pb, As, Sb, Bi.); G01 (Inorganic pigments and non-fibrous fillers (C09C).); G02 (Inks, paints, polishes – polymer-based paints and inks are also classified in Section A (C09D, F, G).)




Patent number: US2006045831-A1;WO2006024959-A2;BR200403713-A;NO200701088-A;EP1807475-A2;AU2005278909-A1;KR2007060084-A;CN101018831-A;JP2008511530-W;IN200701542-P1;BR200514279-A;MX2007002326-A1;KR1060852-B1;WO2006024959-A3;AU2005278909-B2;CA2577927-C;CN101018831-B;JP5496459-B2;IN288652-B




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