Use of transition metal compounds in imageable coatings

A method for forming an image on a substrate, which comprises coating the substrate with a substantially visible light-transparent aqueous dispersion or suspension, of an amine compound of molybdenum, tungsten or vanadium that changes colour on heating or irradiation, and heating or irradiating the coating, wherein the amine is a secondary or tertiary alkylamine in which each alkyl group has up to 12 carbon atoms, and the amine has up to 24 carbon atoms wherein the amine compound is of molybdenum (VI).

A coated substrate, wherein the coating is a substantially visible light-transparent layer comprising an amine compound of molybdenum, tungsten or vanadium that changes colour on heating or irradiation, wherein the amine is a secondary or tertiary alkylamine in which each alkyl group has up to 12 carbon atoms and the amine has up to 24 carbon atoms, and wherein the substrate is also substantially transparent to visible light, wherein the amine compound is of molybdenum (VI).

A solution of an amine compound of molybdenum, tungsten or vanadium that changes colour on heating or irradiation and one of the following:

• a thermoplastic polymer;
• or a photopolymerisable monomer,
• and wherein the amine is a secondary or tertiary alkylamine in which each alkyl group has up to 12 carbon atoms and the amine has up to 24 carbon atoms, wherein the amine compound is of molybdenum (VI).

A method for forming an image on a substrate, which comprises coating the substrate with a substantially visible light-transparent solution, in an organic solvent, of an amine compound of molybdenum, tungsten or vanadium that changes colour on heating or irradiation, and heating or irradiating the coating, wherein the amine is a secondary or tertiary alkylamine in which each alkyl group has up to 12 carbon atoms and the amine has up to 24 carbon atoms, wherein the coating is irradiated using a laser, and wherein the laser light has a wavelength of 800-1500 nm.

A method for forming an image on a substrate, which comprises coating the substrate with a substantially visible light-transparent aqueous dispersion or suspension, of an amine compound of molybdenum, tungsten or vanadium that changes colour on heating or irradiation, and heating or irradiating the coating, wherein the amine is a secondary or tertiary alkylamine in which each alkyl group has up to 12 carbon atoms and the amine has up to 24 carbon atoms, wherein the coating is irradiated using a laser, and wherein the laser light has a wavelength of 800-1500 nm.