Aqueous pigmented inks for ink jet printers

Claim 1

A pigmented ink comprising an aqueous carrier medium and particles of pigment stabilized by an AB or BAB block copolymer wherein: (a) the A segment is a hydrophobic homopolymer or copolymer of an acrylic monomer having the formula CH.sub.2 ═C(X)(Y) wherein X is H or CH 3; and Y is C(0)OR 1 , C(O)NR 2 R 3 , or CN, wherein R 1 is an alkyl, aryl, or alkylaryl group having 1 to 20 carbon atoms, and R 2 and R 3 are hydrogen or an alkyl, aryl, or alkylaryl group having 1 to 9 carbon atoms; said A segment having an average molecular weight of at least approximately 300 and being water insoluble; and (b) the B segment is a hydrophilic polymer, or salt thereof, of (1) an acrylic monomer having the formula CH.sub.2 ═C(X) (Y.sup.1), wherein X is H or CH 3; and Y 1 is C(O)OH, C(O)NR 2 R 3 , C(O)OR 4 NR 2 R 3 or C(O)OR 5 ; wherein R 2 and R 3 are hydrogen or an alkyl, aryl, or alkylaryl group having 1 to 9 carbon atoms; R 4 is an alkyl diradical having 1 to 5 carbon atoms; and R 5 is an alkyl group having 1 to 20 carbon atoms and containing one or more hydroxyl or ether groups; or (2) a copolymer of the acrylic monomer of (1) with an acrylic monomer having the formula CH.sub.2 ═C(X)(Y) where X and Y are the substituent groups defined for said A segment; said B segment having an average molecular weight of at least approximately 300 and being water soluble, with the proviso that said B segment(s) constitute approximately 10 to 90% of said block copolymer, by weight.