Patent ID: 7723402

Claim:
An ink comprising: a solvent; a colorant; and a binder polymer, wherein the ink is characterized by having a surface tension of from about 20 mN/m to about 60 mN/m, a viscosity of less than 50 centipoise, and good adhesion to a medical device, wherein the binder polymer is a poly(vinyl alcohol) or a derivative thereof which comprises multiple olefinically unsaturated groups and is capable of being crosslinked under free radical polymerization conditions in the absence of a crosslinker to form inter- and intra crosslinkages so that a macromolecular matrix is formed to bind and/or trap pigments onto a medical device and to ensure no visible and microscopic (˜10×) observation of colorant bleeding, smearing, or delamination in a color image printed on the medical device with said ink, wherein each intra-crosslinkage is an intramolecular covalent bond formed between a pair of olefinically unsaturated groups which belong to the same binder polymer molecule, wherein the inter-crosslinkage is an intermolecular covalent bond formed between a pair of olefinically unsaturated groups each belonging to one of two binder polymer molecules.