| abstract |
An ink composition comprising (a) water, (b) pigment particles, (c) at least one humectant, (d) at least one polyurethane having an average molecular weight of at least 10,000 and a sufficient number of acid groups to provide an acid number from 60 to 130, and being present at a weight concentration of greater than 0.7%, and (e) at least one water soluble acrylic polymer comprising carboxylic acid groups, present at a weight concentration of greater than 0.6%, wherein the acid groups on the polyurethane and acrylic polymers are at least partially neutralized only with a monovalent inorganic base. |