Patent ID: 11891527
Assignee: SICPA HOLDING SA
Field: Basic materials chemistry (Chemistry)
Classification: CPC C  B | IPC B  C

Claim 7:
8. The security ink according to claim 1, wherein the one or more IR absorbing materials are prepared by a method comprising the followings steps:
a) manufacturing a mixture containing:
i) iron compounds (A) selected from Fe(III) compounds, Fe(III)/Fe(II) compounds and mixtures of these in a percentage of about 20 wt-% to about 90 wt-% by weight of the mixture, selected from the group consisting of oxides, hydroxides, oxide hydroxides, carbonates, carboxylates such as oxalates, formates, acetates, citrates, lactates, orthophosphates, phosphonates, metaphosphonates, pyrophosphates, sulfates and mixtures thereof,
ii) reduction agents (B) in a percentage of about 5 wt-% to about 50 wt-% by weight of the mixture, selected from the group consisting of phosphonic acid [H3PO3], phosphorus trioxide [P2O3], phosphinic acid [H3PO2], phosphorus tetroxide [P2O4], hypodiphosphoric acid [H4P2O6], diphosphoric acid [H4P2O5], hypodiphosphonic acid [H4P2O4], Fe salts and Met salts of the above mentioned acids, and mixtures thereof as solids, aqueous solutions or suspensions,
iii) optional phosphate donor (C) in a percentage of about 0 wt-% to about 50 wt-% by weight of the mixture, selected from the group consisting of phosphoric acid [H3PO4] as an aqueous solution, metal phosphate [Metx(PO4)z] or acid metal phosphate [MetxHγ(PO4)z] with 1≥x≥4, 1≥y≥5 and 1≥z≥4 as a solid or aqueous solutions or suspension, diphosphoric acid [H4P2O7], metaphosphoric acid [(HPO3)n] with n≥3 or their salts, phosphorus pentoxide [P2O5], and mixtures thereof, and
iv) optional metal (M) donor (D) in a percentage of about 0 wt-% to about 50 wt-% by weight of the mixture, selected from metal compounds of one or more metals from the group consisting of K, Rb, Cs, Mg, Ca, Sr, Ba, Sc, Y, La, Ti, Zr, Hf, Nb, Ta, Cr, Mo, W, Mn, Cu, Zn, B, Al, Ga, In, Si, Sn, Sb, Bi, and the lanthanoids, and selected from the group consisting of oxides, hydroxides, oxide hydroxides, carbonates, oxalates, formates, acetates, citrates, lactates, orthophosphates, pyrophosphates and sulfates of the above mentioned metals and mixtures thereof,
wherein the weight percentage of each of the components (A) to (D) of the mixture is based on a percentage of each of the components (A) to (D) not including any solvent and/or suspension agent,
b) obtaining the mixture, wherein the mixture contains aqueous and/or organic solvents, and is dried at a temperature of less than about 400° C., and
c) treating the dry or dried mixture at a temperature between about 400 and about 1200° C.