# US 9,752,038 B2 · Water-based ink for ink-jet recording, and ink-jet recording method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,752,038 B2 - Document ID: US9752038B2 - Status: Granted - Kind: B2 - Application number: 14/867,747 - Filed: 2015-09-28 - Published: 2016-10-06 - Granted: 2017-09-05 - Earliest claimed: 2015-03-31 - Assignees: Brother Kogyo Kabushiki Kaisha - Applicants: Brother Kogyo Kabushiki Kaisha - Inventors: Yuki Okumura; Mitsunori Maeda - Web page: https://patentgrep.com/patent/US9752038B2 ## CPC - C09D 11/322: Pigment inks - C09D 11/00: Inks - C09D 11/30: Inkjet printing inks - C09D 11/38: characterised by non-macromolecular additives other than solvents, pigments or dyes - 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 There is provided a water-based ink for ink-jet recording containing: a pigment; a surfactant; and water, wherein dynamic surface tension of the water-based ink measured under a condition of temperature of 25 degrees Celsius and lifetime of 10 ms is not less than 35 mN/m; and dynamic surface tension of the water-based ink measured under a condition of temperature of 25 degrees Celsius and lifetime of 50 ms is not more than 34.5 mN/m. ## Claims ### Claim 1 A water-based ink for ink-jet recording comprising: a pigment; a nonionic surfactant; an anionic surfactant; and water, wherein dynamic surface tension of the water-based ink measured under a condition of temperature of 25 degrees Celsius and lifetime of 10 ms is not less than 35 mN/m; dynamic surface tension of the water-based ink measured under a condition of temperature of 25 degrees Celsius and lifetime of 50 ms is not more than 34.5 mN/m; and a weight ratio (A/N) of a blending amount (A) of the anionic surfactant to a blending amount (N) of the nonionic surfactant in the water-based ink is in a range of 0.28 to 0.70. ### Claim 2 (depends on 1) The water-based ink for ink-jet recording according to claim 1, wherein the dynamic surface tension of the water-based ink measured under the condition of temperature of 25 degrees Celsius and lifetime of 10 ms is in a range of 35.5 mN/m to 38 mN/m. ### Claim 3 (depends on 1) The water-based ink for ink-jet recording according to claim 1, wherein the surfactant is a nonionic surfactant, and HLB of the nonionic surfactant is in a range of 8 to 12. ### Claim 4 (depends on 1) The water-based ink for ink-jet recording according to claim 1, wherein the surfactant is a nonionic surfactant, and HLB of the nonionic surfactant is in a range of 8 to 9. ### Claim 5 (depends on 1) The water-based ink for ink-jet recording according to claim 1, wherein the surfactant is an acetylenic glycol-based nonionic surfactant. ### Claim 6 (depends on 1) The water-based ink for ink-jet recording according to claim 1, wherein the surfactant is an acetylenic glycol-based nonionic surfactant represented by the following formula (1): in the formula (1), “m” and “n” are identical to each other, and are numbers satisfying: m+n=1 to 15; and R1, R2, R3 and R4 are identical to one another or different from one another, and each of R1, R2, R3 and R4 is a straight-chain or branched-chain alkyl group of which carbon atom number is 1 to 5. ### Claim 7 (depends on 6) The water-based ink for ink-jet recording according to claim 6, wherein in the formula (1), the “m” and “n” are numbers satisfying: m+n=1 to 6. ### Claim 8 (depends on 6) The water-based ink for ink-jet recording according to claim 6, wherein the pigment and the acetylenic glycol-based nonionic surfactant represented by the formula (1) are blended in the water-based ink so as to satisfy the following condition (I): (N1/P)×100≧3.3 condition (I): in the condition (I), N1 represents a blending amount (% by weight) of the acetylenic glycol-based nonionic surfactant represented by the formula (1) in an entire amount of the water-based ink; and P represents a blending amount (% by weight) of the pigment in the entire amount of the water-based ink. ### Claim 9 (depends on 1) The water-based ink for ink-jet recording according to claim 1, wherein the surfactant is a nonionic surfactant represented by the following formula (2): in the formula (2), “x” is a positive integer in a range of 3 to 10. ### Claim 10 (depends on 6) The water-based ink for ink-jet recording according to claim 6, wherein a content of the acetylenic glycol-based nonionic surfactant represented by the formula (1) in the water-based ink is in a range of 0.2% by weight to 0.6% by weight. ### Claim 11 (depends on 1) The water-based ink for ink-jet recording according to claim 1, further comprising glycerol, and a content of the glycerol in the water-based ink is in a range of 8% by weight to 30% by weight. ### Claim 12 (depends on 6) The water-based ink for ink-jet recording according to claim 6, further comprising glycerol; wherein a weight ratio (G/N1) of a blending amount (G) of the glycerol to a blending amount (N1) of the acetylenic glycol-based nonionic surfactant represented by the formula (1) in the water-based ink is in a range of 15 to 95. ### Claim 13 (depends on 1) The water-based ink for ink-jet recording according to claim 1, wherein a difference obtained by subtracting the dynamic surface tension of the water-based ink measured under the condition of temperature of 25 degrees Celsius and lifetime of 10 ms from the dynamic surface tension of the water-based ink measured under the condition of temperature of 25 degrees Celsius and lifetime of 50 ms is in a range of 2.0 to 5.0. ### Claim 14 (depends on 1) The water-based ink for ink-jet recording according to claim 1, wherein the pigment is a self-dispersible pigment. ### Claim 15 (depends on 1) The water-based ink for ink-jet recording according to claim 1, wherein the pigment is a self-dispersible pigment modified by a carboxyl group. ### Claim 16 (depends on 1) The water-based ink for ink-jet recording according to claim 1, wherein a content of the pigment in the water-based ink is not less than 7% by weight. ### Claim 17 An ink-jet recording method comprising: preparing a water-based ink for ink-jet recording which contains a pigment, a nonionic surfactant, anionic surfactant, and water, wherein dynamic surface tension of the water-based ink measured under a condition of temperature of 25 degrees Celsius and lifetime of 10 ms is not less than 35 mN/m, and dynamic surface tension of the water-based ink measured under a condition of temperature of 25 degrees Celsius and lifetime of 50 ms is not more than 34.5 mN/m, and a weight ratio (A/N) of a blending amount (A) of the anionic surfactant to a blending amount (N) of the nonionic surfactant in the water-based ink is in a range of 0.28 to 0.70; and discharging, to a recording medium, the water-based ink by an ink-jet system. ### Claim 18 (depends on 17) The ink-jet recording method according to claim 17, wherein an ink-jet head of a piezoelectric system is used to discharge the water-based ink onto the recording medium. ### Claim 19 (depends on 17) The ink-jet recording method according to claim 17, wherein an ink-jet head, having a plurality of nozzles which are formed in the ink-jet head and of which inner diameter is in a range of 10 μm to 30 μm, is used to discharge the water-based ink from the plurality of nozzles onto the recording medium. ### Claim 20 (depends on 2) The water-based ink for ink-jet recording according to claim 2, wherein dynamic surface tension of the water-based ink measured under a condition of temperature of 25 degrees Celsius and lifetime of 50 ms is in a range of 32.0 mN/m to 33.8 mN/m. ### Claim 21 (depends on 2) The water-based ink for ink-jet recording according to claim 2, wherein dynamic surface tension of the water-based ink measured under a condition of temperature of 25 degrees Celsius and lifetime of 50 ms is in a range of 31.4 mN/m to 33.8 mN/m.