Ink compositions with liposomes containing photochromic compounds

A printing process which comprises incorporating into an ink jet printer an ink composition which comprises an aqueous liquid vehicle, a photochromic material, and a vesicle-forming lipid, wherein vesicles of the lipid are present in the ink, and causing droplets of the ink to be ejected in imagewise pattern onto a substrate.

A printing process which comprises incorporating into an ink jet printer a first ink composition which comprises a first aqueous liquid vehicle, a first material selected from the group consisting of dyes and photochromic materials, and a first vesicle-forming lipid, wherein vesicles of the first lipid are present in the first ink, and a second ink composition which comprises a second aqueous liquid vehicle, a second material selected from the group consisting of dyes and photochromic materials, and a second vesicle-forming lipid, wherein vesicles of the second lipid are present in the second ink, causing droplets of the first ink to be ejected in imagewise pattern onto a substrate heated to a temperature above about 25.degree. C., and subsequently causing droplets of the second ink to be ejected in imagewise pattern onto the heated substrate, wherein at least one of the first ink and the second ink contains a photochromic material.

A process which comprises (a) incorporating into an ink jet printer an ink composition which comprises an aqueous liquid vehicle, a photochromic material having a first state corresponding to a first absorption spectrum and a second state corresponding to a second absorption spectrum, and a vesicle-forming lipid, wherein vesicles of the lipid are present in the ink;

• (b) causing droplets of the ink to be ejected in imagewise pattern onto a substrate;
• and (c) thereafter effecting a photochromic change in at least some of the photochromic material on the substrate from the first state to the second state.