Electromagnetic radiation or thermally sensitive composition
The present invention provides coating compositions comprising (i) a) a compound containing a free carbonyl group and b) a nucleophile or (ii) a compound containing a free carbonyl group, which compound is substituted with one or more nucleophilic groups. The present invention also provides a process for the preparation of these compositions, substrates coated with these compositions and a process for their preparation, a process for preparing marked substrates using these compositions, and marked substrates obtainable by the latter process.
1. A coating composition comprising
a) a reducing carbohydrate selected from at least one of an aldose, a ketose, a reducing oligosaccharide and a reducing polysaccharide, and
b) an amine selected from at least one of an amino acid and an amino sugar,
wherein the molar ratio of the reducing carbohydrate to the amine is in the range of 10:1 to 1:10.
2. The coating composition of claim 1 , wherein the amine is at least one of 4-aminohippuric acid, 4-aminobenzoic acid, glycine, alanine, valine, leucine, isoleucine, proline, phenylalanine, tyrosine, tryphthophane, cysteine, methionine, serine, threonine, lysine, arginine, histidine, aspartic acid, glutamic acid, asparagine and glutamine.
3. The coating composition of claim 1 , wherein the amine is glucosamine or galactosamine.
4. The coating composition of claim 1 , wherein the reducing carbohydrate is glucose.
5. The coating composition of claim 1 , which also comprises a solvent.
6. The coating composition of claim 1 , which also comprises a polymeric binder.
7. The coating composition of claim 1 , which also comprises a catalyst.
8. A substrate coated with the coating composition of claim 1 .
9. A process for preparing a marked substrate, which comprises exposing those parts of the coated substrate of claim 8 , where marking is intended, to energy in order to generate a marking.