Use of an additive in the production of copper(II) hydroxide phosphate

1 . A method for preparing copper(II) hydroxide phosphate comprising:

a) producing a reaction mixture from an aqueous solution or dispersion of a copper(II) compound and phosphoric acid,

b) converting the copper(II) compound with the phosphoric acid in the reaction mixture, and phosphoric acid

c) separating copper(II) hydroxide phosphate from the reaction mixture,

wherein the conversion in step b) is effected in an unpressurized manner,

wherein at least one chelating agent is added to the reaction mixture in method step a) and/or b), wherein if the chelating agent is a phosphoric acid or a salt thereof, the phosphoric acid or the salt is a di- or polyphosphoric acid or a salt thereof.

2 . The method according to claim 1 , wherein the at least one chelating agent is selected from the group consisting of amino, carboxylic, phosphoric, sulfuric and sulfonic acids and the salts, esters and amides thereof, polyvalent alcohols, nitriles, bipyridines, phenanthrolines, polyvalent phenols, polyvalent amines, polyvalent ethers, lactams, oximes, urea derivatives, polyvalent ketones and aldehydes, thiols, and combinations thereof.

3 . The method according to claim 1 , wherein the copper(II) compound is selected from the group consisting of copper(II) hydroxide, copper(II) sulfate, copper(II) carbonate, basic copper(II) carbonate, copper(II) halides, and combinations thereof.

4 . The method according to claim 1 , wherein the at least one chelating agent is an amino acid or the salt thereof, wherein the amino acid is selected from the group of proteinogenic amino acids.

5 . The method according to claim 1 , wherein the at least one chelating agent is a carboxylic acid, a hydroxycarboxylic acid or the salt thereof, wherein the carboxylic acid or hydroxycarboxylic acid is selected from the group consisting of formic acid, acetic acid, glycolic acid, lactic acid, benzoic acid, oxalic acid, tartaric acid, malic acid, citric acid, isocitric acid, trimesic acid and combinations thereof.

6 . The method according to claim 1 , wherein the at least one chelating agent is a saccharide selected from the group consisting of mono- and oligosaccharides.

7 . The method according to claim 1 , wherein the at least one chelating agent is ascorbic acid.

8 . The method according to claim 1 , wherein the at least one chelating agent is a surfactant.

9 . The method according to claim 1 , wherein the at least one chelating agent is added in a total amount of chelating agents of from 0.1 to 5.0 wt.-% in relation to the amount of the copper(II) compound.

10 . The method according to claim 1 , wherein the copper(II) hydroxide phosphate obtained in method step c) has a phase purity of >95%.

11 . The method according to claim 1 , wherein in the CIELAB L*a*b* colour space in accordance with DIN EN ISO 11664-4, the copper(II) hydroxide phosphate obtained in method step c) has an L* value of >80.

12 . The-method according to claim 1 , wherein the copper(II) hydroxide phosphate obtained in method step c) consists of particles that have a median particle size in the range of from 2 to 10 μm after determination using laser diffraction analysis in accordance with DIN-ISO 13320-1.

13 . The method according to claim 1 , wherein the copper(II) hydroxide phosphate obtained in method step c) consists of particles that are rod-shaped, wherein the aspect ratio is in the range of from 1:3 to 1:10.

14 . A copper(II) hydroxide phosphate prepared by the method according to claim 1 , wherein the copper(II) hydroxide phosphate has an L value in the L*a*b* colour space of >78.

15 . A method for preparing copper(II) hydroxide phosphate comprising:

a) producing a reaction mixture from an aqueous solution or dispersion of a copper(II) compound and phosphoric acid,

b) converting the copper(II) compound with the phosphoric acid in the reaction mixture and

c) separating copper(II) hydroxide phosphate from the reaction mixture,

wherein the conversion in step b) is effected in an unpressurized manner,

wherein at least one chelating agent is added to the reaction mixture in method step a) and/or b), and

wherein the copper(II) hydroxide phosphate obtained in method step c):

i) has a phase purity of >95%,

ii) has an L* value of >80 in the CIELAB L*a*b* colour space in accordance with DIN EN ISO 11664-4,

iii) consists of particles that have a median particle size in the range of from 2 to 10 μm after determination using laser diffraction analysis in accordance with DIN-ISO 13320-1, and/or

iv) consists of particles that are rod-shaped, wherein the aspect ratio is in the range of from 1:3 to 1:10.

16 . A copper(II) hydroxide phosphate prepared by the method according to claim 15 , wherein the copper(II) hydroxide phosphate has an L value in the L*a*b* colour space of >78.