Patent ID: 7317042

Claim:
An ink jet ink composition comprising water, a humectant, a surfactant, and composite polymer-dye particles, wherein said polymer-dye particles comprise a colorant phase containing a water insoluble dye and a water-insoluble polymer phase, said particles being associated with a water-dispersible polyester polymeric co-stabilizer, wherein the mean particle size of the water-dispersible polyester co-stabilizer is less than 200 nm, and wherein the composite polymer-dye particles are made by a process comprising the steps of: I) forming a colorant mixture comprising a water insoluble dye and an organic medium containing at least one ethylenically-unsaturated monomer; II) combining said colorant mixture with an aqueous mixture comprising a surfactant and said water-dispersible polyester co-stabilizer to form a colorant mixture/aqueous mixture; III) causing the colorant mixture/aqueous mixture to form a stable aqueous droplet mixture by using strong agitation; and IV) initiating polymerization to form composite polymer-dye particles comprising a colorant phase and a water insoluble polymer phase; wherein an addition polymerization initiator is added prior to initiating polymerization; and wherein polymer formed is a cross-linked polymer and the organic medium contains a mixture of ethylenically-unsaturated monomers comprising: a) at least one ethylenically-unsaturated monomer that is free of ionic charge groups and undergoes addition polymerization to form a substantially water-insoluble homopolymer; and b) at least one ethylenically-unsaturated monomer that is a cross-linker.