# US 10,766,993 B2 · ABA block copolymer, dispersant, and pigment dispersion composition > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,766,993 B2 - Document ID: US10766993B2 - Status: Granted - Kind: B2 - Application number: 16/068,198 - Filed: 2017-01-13 - Published: 2019-01-03 - Granted: 2020-09-08 - Earliest claimed: 2016-02-03 - Assignees: Otsuka Chemical Co., Ltd. - Applicants: Otsuka Chemical Co., Ltd. - Inventors: Hikaru Umemoto - Web page: https://patentgrep.com/patent/US10766993B2 ## CPC - C08F 293/005: {using free radical "living" or "controlled" polymerisation, e.g. using a complexing agent} - B41M 5/00: Duplicating or marking methods; Sheet materials for use therein (by using light-sensitive materials G03; electrography, magnetography G03G {; repeatedly usable boards or tablets for writing or drawing B43L1/00}) - B41M 5/0023: {Digital printing methods characterised by the inks used (inks per se C09D11/00)} - C08F 293/00: Macromolecular compounds obtained by polymerisation on to a macromolecule having groups capable of inducing the formation of new polymer chains bound exclusively at one or both ends of the starting macromolecule (on to polymers modified by introduction of unsaturated end groups C08F290/02) - C09D 11/033: characterised by the solvent - C09D 11/037: characterised by the pigment - C09D 11/106: containing macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds - C09D 11/107: from unsaturated acids or derivatives thereof - C09D 11/322: Pigment inks - C09D 11/326: characterised by the pigment dispersant - C09D 153/00: Coating compositions based on block copolymers containing at least one sequence of a polymer obtained by reactions only involving carbon-to-carbon unsaturated bonds; Coating compositions based on derivatives of such polymers - C08F 2438/00: Living radical polymerisation - C08F: MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS - B41M: PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING, (correction of typographical errors B41J; processes for applying transfer pictures or the like B44C1/16; fluid media for correction of typographical errors by coating C09D10/00; printing textiles D06P) - C09D: COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR (cosmetics A61K; processes for applying liquids or other fluent materials to surfaces, in general, B05D; staining wood B27K5/02; glazes or vitreous enamels C03C; natural resins, French polish, drying-oils, driers, turpentine, per se, C09F; polishing compositions other than French polish, ski waxes C09G; adhesives or use of materials as adhesives C09J; materials for sealing or packing joints or covers C09K3/10; materials for stopping leaks C09K3/12; processes for the electrolytic or electrophoretic production of coatings C25D) ## Abstract Provided is an ABA block copolymer that can offer a pigment dispersion composition having excellent dispersion stability when used as a pigment dispersant in an aqueous medium. An ABA block copolymer including: an A block containing a structural unit represented by a general formula (1) below and a structural unit derived from a vinyl monomer with an acid group; and a B block containing a structural unit derived from a vinyl monomer with an aromatic ring group or an alicyclic alkyl group, the ABA block copolymer having an acid value of 30 to 250 mgKOH/g. In the general formula (1), R1 is a hydrogen atom or a methyl group and R2 is an alkyl group having 2 to 10 carbon atoms. ## Claims ### Claim 1 An ABA block copolymer comprising: an A block containing a structural unit represented by a general formula (1) below and a structural unit derived from a vinyl monomer with an acid group; and a B block containing a structural unit derived from a vinyl monomer with an aromatic ring group or an alicyclic alkyl group, the ABA block copolymer having an acid value of 30 to 250 mgKOH/g, wherein in the general formula (1) R1 is a hydrogen atom or a methyl group and R2 is an alkyl group having 2 to 10 carbon atoms, the structural unit represented by the general formula (1) is at a content of 20 to 80% by mass in 100% by mass of the A block and wherein the content of the structural unit derived from a vinyl monomer with an acid group is, in 100% by mass of the A block, 5 to 40% by mass. ### Claim 2 (depends on 1) The ABA block copolymer according to claim 1, wherein the acid group is at least one selected from the group consisting of a carboxyl group, a sulfonic acid group, and a phosphoric acid group. ### Claim 3 (depends on 1) The ABA block copolymer according to claim 1, wherein a content of the B block is 20 to 80% by mass in 100% by mass of the entire ABA block copolymer. ### Claim 4 (depends on 1) The ABA block copolymer according to claim 1, wherein the ABA block copolymer has a polydispersity index (PDI) of less than 2.0. ### Claim 5 (depends on 1) The ABA block copolymer according to claim 1, wherein the ABA block copolymer is formed by living radical polymerization. ### Claim 6 (depends on 1) A dispersant containing the ABA block copolymer according to claim 1 and/or a neutralized product of the ABA block copolymer. ### Claim 7 (depends on 6) A pigment dispersion composition containing the dispersant according to claim 6, a pigment, and an aqueous dispersion medium. ### Claim 8 (depends on 7) The pigment dispersion composition according to claim 7, wherein the pigment dispersion composition is an ink-jet ink.