Aluminum phosphate or polyphosphate particles for use as pigments in paints and method of making same
AssigneesBunge Amorphic Solutions LLC, Universidade Estadual De Campinas
InventorsFernando Galembeck, João de Brito
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Abstract
An aluminum phosphate or polyphosphate-based pigment product is made by a process comprising contacting phosphoric acid with aluminum sulfate and an alkaline solution to produce an aluminum phosphate based product; and optionally calcining the aluminum phosphate based product at an elevated temperature, wherein the process is substantially free of an organic acid. The aluminum phosphate or polyphosphate-based pigment is amorphous. The amorphous aluminum phosphate or polyphosphate characterized by a bulk density of less than 2.30 grams per cubic centimeter and a phosphorus to aluminum mole ratio of greater than 0.8. The composition is useful in paints and as a substitute for titanium dioxide.
Claims42
A method of making a coating composition comprising an aluminum phosphate opacifying pigment consisting of amorphous aluminum phosphate, the method comprising the steps of:
- combining phosphoric acid with aluminum sulfate and sodium hydroxide to form a reactive mixture that forms an amorphous aluminum phosphate precipitate;
- drying the precipitate at a temperature less than about 130° C., wherein the dried precipitate is substantially free of open pores;
- and
- adding the amorphous aluminum phosphate to a binding polymer to form the coating composition, wherein the amorphous aluminum phosphate has a bulk density that is less than about 2.1 g/cc, wherein the amorphous aluminum phosphate has an average individual particle radius size from about 5 to 80 nanometers, and wherein the coating composition when dried to form a film has a structure characterized by enmeshed binding polymer and amorphous aluminum phosphate.
A method of making a coating composition comprising an aluminum phosphate opacifying pigment that consists of amorphous aluminum phosphate, the method comprising the steps of:
- combining phosphoric acid with aluminum sulfate and sodium hydroxide to form a mixture;
- reacting the mixture to form an amorphous aluminum phosphate precipitate, wherein the amorphous aluminum phosphate has a phosphorous to aluminum mole ratio of greater than about 0.8;
- and
- drying the precipitate at a temperature less than about 130° C., wherein the dried precipitate is substantially free of open pores;
- and
- adding the amorphous aluminum phosphate to a binding polymer to form the coating composition, wherein the amorphous aluminum phosphate has a bulk density that is less than about 2.1 g/cc.
A method of making a coating composition comprising an aluminum phosphate opacifying pigment consisting of amorphous aluminum phosphate, the method comprising the steps of:
- combining phosphoric acid with aluminum sulfate and sodium hydroxide to form a mixture;
- reacting the mixture to form an amorphous aluminum phosphate suspension;
- filtrating and washing the suspension into a cake;
- forming a dispersion of the washed cake;
- drying the cake to form amorphous aluminum phosphate particles, wherein the dried particles are substantially free of open pores;
- and
- adding the amorphous aluminum phosphate to a binding polymer to form the coating composition, wherein the amorphous aluminum phosphate has a bulk density that is less than about 2.1 g/cc, and wherein the coating composition when dried to form a film has a structure characterized by interpenetrating phases of binding polymer enmeshed with amorphous aluminum phosphate.
A method of making a coating composition comprising an aluminum phosphate opacifying pigment consisting of amorphous aluminum phosphate, the method comprising the steps of:
- simultaneously combining phosphoric acid with aluminum sulfate and an alkaline solution to form a mixture;
- reacting the mixture to form an amorphous aluminum phosphate precipitate, wherein the amorphous aluminum phosphate has a phosphorous to aluminum mole ratio of greater than 0.8;
- and
- drying the precipitate at a temperature less than about 130° C., wherein when in a powder form the amorphous aluminum phosphate has one to four closed voids per particle and has a macropore volume of substantially less than 0.1 cc/gram, wherein the amorphous aluminum phosphate has an average individual particle radius size of between 5 and 80 nanometers, and wherein the amorphous aluminum phosphate has a bulk density of less than 2.1 grams/cc;
- and
- adding the amorphous aluminum phosphate to a binding polymer to form the coating composition, and wherein the coating composition comprises a water-borne latex.
Dependencies are inferred from the claim text.