Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • 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
  • C09D11/00—Inks
  • C09D11/30—Inkjet printing inks
  • C09D11/32—Inkjet printing inks characterised by colouring agents
  • C09D11/322—Pigment inks
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • 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
  • C09D11/00—Inks
  • C09D11/30—Inkjet printing inks
  • C09D11/40—Ink-sets specially adapted for multi-colour inkjet printing

Definitions

• the present invention relates to an ink set.
• the present invention relates to an ink set suitable as an inkjet ink, particularly with improved green saturation.
• Inkjet recording is a method of recording in which ink droplets are ejected from extremely fine nozzles directly onto a recording medium to produce characters or images.
• This method has the advantages of low noise and good operability of the equipment used, as well as the ease of colorization and the ability to use plain paper as the recording medium, and therefore has come to be widely used in output devices in offices and homes in recent years. Meanwhile, with technological improvements in inkjet recording methods, industrial printers are also expected to be used as output devices for digital printing, and some printers are replacing analog printers.
• Patent Literature 2 discloses an ink set for inkjet recording, which includes a yellow ink, a magenta ink, and a cyan ink, and contains a specific pigment and a specific type of dispersant, and is said to improve the chroma of images and have excellent storage stability of the inks.
• An object of the present invention is to provide an ink set which has excellent saturation of primary and secondary colors, particularly excellent saturation of green, and which has excellent abrasion resistance of printed images.
• a yellow ink containing a binder, a dispersion resin, an aqueous solvent, and C.I. Pigment Yellow 74 as a pigment An ink set comprising a binder, a dispersion resin, an aqueous solvent, and a cyan ink containing C.I. Pigment Blue 15:3 as a pigment,
• the volume average particle diameter of the C.I. Pigment Yellow 74 is 80 to 120 nm, and the content of the C.I. Pigment Yellow 74 relative to the total amount of the yellow ink is 4.0 to 10.0% by mass,
• Pigment Blue 15:3 has a volume average particle diameter of 80 to 100 nm, and its content relative to the total amount of the cyan ink is more than 2.5% by mass and less than 5.5% by mass.
• the minimum film-forming temperature of the binder is 25° C. or higher;
• a magenta ink containing a binder, a dispersion resin, an aqueous solvent, and a solid solution pigment is provided,
• the solid solution pigment is composed of C.I. Pigment Red 122 and C.I.
• Pigment Violet 19 The mass ratio of C.I. Pigment Red 122 to C.I. Pigment Violet 19 in the solid solution pigment is 4/1 to 1/1;
• the volume average particle size of the solid solution pigment is 90 to 130 nm,
• the present invention provides an ink set that has excellent saturation of primary and secondary colors, particularly the saturation of green, and has excellent abrasion resistance of printed images.
• the present invention relates to an ink set including a yellow ink containing a binder, a dispersion resin, an aqueous solvent, and C.I. Pigment Yellow 74 as a pigment, and a cyan ink containing a binder, a dispersion resin, an aqueous solvent, and C.I. Pigment Blue 15:3 as a pigment,
• the volume average particle diameter of the C.I. Pigment Yellow 74 is 80 to 120 nm, and the content of the C.I. Pigment Yellow 74 relative to the total amount of the yellow ink is 4.0 to 10.0% by mass
• the volume average particle diameter of the C.I. Pigment Blue 15:3 is 80 to 100 nm, and the content of the C.I. Pigment Blue 15:3 relative to the total amount of the cyan ink is more than 2.5% by mass and less than 5.5% by mass.
• the ink set of the present invention is excellent in chroma of primary and secondary colors.
• the chroma (c * ) of green in particular can be improved without decreasing the color development of the secondary colors blue and red.
• the minimum film-forming temperature of the binder is 25° C. or higher, and the volume average particle diameter of the binder is equal to or smaller than the volume average particle diameter of at least one of the C.I. Pigment Yellow 74 and C.I. Pigment Blue 15:3, so that the ink set has excellent abrasion resistance of printed images.
• the pigment contained in the yellow ink is C. I. Pigment Yellow 74.
• the content of C. I. Pigment Yellow 74 relative to the total amount of the yellow ink is 4.0 to 10.0% by mass, and a range of 4.5 to 9.0% by mass is more preferable.
• the volume average particle diameter of C.I. Pigment Yellow 74 is 80 to 120 nm, and more preferably 90 to 110 nm.
• the volume average particle diameter of C.I. Pigment Yellow 74 is determined by a dynamic light scattering method, a laser diffraction method, or the like, which are general measurements of pigment dispersion particles.
• the pigment particles which are a dispersion liquid
• a laser scattering type particle size measuring device Nanotrac Wave II, manufactured by Microtrac, Inc.
• the volume average particle diameter of C.I. Pigment Yellow 74 can be measured under the set conditions of a measurement time of 180 seconds and a number of repeated measurements of 3, with the dilution ratio adjusted so that the loading index value is 1.
• the binder contained in the yellow ink is used for the purpose of fixing the pigment in the ink to the recording medium. Unlike the dispersion resin described below, the binder is not adsorbed to the surface of the pigment in the ink, but is present in the ink dispersed in the aqueous solvent separately from the pigment and dispersion resin.
• the minimum film-forming temperature of the binder is preferably 25° C. or higher, and although it depends on the glass transition temperature of the components constituting the binder, it is usually more preferably in the range of 25° C. to 60° C., and even more preferably in the range of 30° C. to 45° C. When the minimum film-forming temperature of the binder is within the above range, film formation proceeds effectively under general drying conditions, and excellent abrasion resistance is achieved.
• the volume average particle diameter of the binder is preferably equal to or smaller than at least one of the volume average particle diameter of C.I. Pigment Yellow 74, which is a pigment constituting the yellow ink, and the volume average particle diameter of C.I. Pigment Blue 15:3, which is a pigment constituting the cyan ink, and more preferably equal to or smaller than both of the volume average particle diameters. More specifically, the volume average particle diameter of the binder is preferably 100 nm or less, and more preferably in the range of 40 to 80 nm.
• the volume average particle diameter of the binder can be determined by general measurements of dispersed particles, such as dynamic light scattering, laser diffraction, etc.
• the volume average particle diameter of the binder can be measured using a laser scattering type particle size measuring device, Nanotrac Wave II manufactured by Microtrac, Inc., by adjusting the dilution ratio so that the loading index value is 1, and setting the measurement time to 180 seconds and the number of repeated measurements to 3.
• binders include polyvinyl alcohol, gelatin, polyethylene oxide, polyvinylpyrrolidone, acrylic resins, urethane resins, olefin resins, modified polyolefin resins (such as acid-modified polypropylene), dextran, dextrin, carrageenan ( ⁇ , ⁇ , ⁇ , etc.), agar, pullulan, water-soluble polyvinyl butyral, hydroxyethyl cellulose, carboxymethyl cellulose, etc. These may be used alone or in combination of two or more.
• a vinyl polymer (A1) having a structural unit derived from an aromatic vinyl monomer and a glass transition temperature (Tg) of 50 to 100° C., or a vinyl halide polymer (A2) having a Tg of 50 to 100° C. can be used.
• the vinyl polymer (A1) may be a copolymer having a structural unit derived from an aromatic vinyl monomer and a structural unit derived from a (meth)acrylic monomer.
• the aromatic vinyl monomer include styrene, ⁇ -methylstyrene, o-methylstyrene, m-methylstyrene, and p-methylstyrene, and among these, styrene is preferred.
• Examples of the (meth)acrylic monomer include (meth)acrylic acid; and (meth)acrylic acid esters such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, pentyl (meth)acrylate, neopentyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and octyl (meth)acrylate.
• the vinyl polymer (A1) is preferably a styrene-acrylic resin.
• the content of the structural units derived from aromatic vinyl monomers in the total amount of the vinyl polymer (A1) is preferably in the range of 50 to 99 mass%, more preferably 80 to 99 mass%, and the content of the structural units derived from (meth)acrylic monomers in the total amount of the vinyl polymer (A1) is preferably in the range of 1 to 50 mass%, more preferably 1 to 20 mass%.
• Examples of the vinyl halide polymer (A2) include vinyl chloride (co)polymers, chlorinated polyolefins, and chlorinated rubbers, and vinyl chloride-acrylic polymers having structural units derived from vinyl chloride monomers and structural units derived from (meth)acrylic monomers are preferred.
• the (meth)acrylic monomers are as described above.
• the content of the structural units derived from vinyl chloride monomers in the total amount of the halogenated vinyl polymer (A2) is preferably in the range of 30 to 90 mass%, more preferably in the range of 50 to 80 mass%, and the content of the structural units derived from (meth)acrylic monomers in the total amount of the halogenated vinyl polymer (A2) is preferably in the range of 10 to 70 mass%, more preferably in the range of 20 to 50 mass%.
• the vinyl polymer (A) can be produced by emulsion polymerization, solution polymerization, suspension polymerization, bulk polymerization, etc.
• a vinyl polymer (A) having a core-shell structure is more preferred.
• a vinyl polymer having a core-shell structure in which structural units derived from an aromatic vinyl monomer or structural units derived from a vinyl chloride monomer are localized in the core portion, and structural units derived from a (meth)acrylic monomer are localized in the shell portion can be mentioned.
• the vinyl polymer (A) having a core-shell structure can be produced, for example, by polymerizing a monomer component including a (meth)acrylic monomer to produce a polymer (x) constituting the shell, and then supplying an aromatic vinyl monomer or the like to a reaction vessel and polymerizing it within the particles of the polymer (x) to form the core portion.
• vinyl polymer (A) examples include “JONCRYL PDX-7700”, “JONCRYL PDX-7780", “JONCRYL 89-E”, and “JONCRYL 89J” (all trade names (JONCRYL is a registered trademark), manufactured by BASF Japan Ltd.); “Hi-Loss X BE7503” (manufactured by Seiko PMC Corporation), “Vinyblan 745", and “Vinyblan 747” (manufactured by Nissin Chemical Industry Co., Ltd.).
• styrene-acrylic resin is more preferable from the viewpoints of improving the ejection stability of the ink, reducing costs, and improving the print density and image robustness of the resulting prints.
• the weight average molecular weight (Mw) of the binder is preferably 100,000 to 1,000,000, and more preferably 300,000 to 750,000.
• the Mw of the binder is a value measured in terms of standard polystyrene by gel permeation chromatography (GPC), and was determined by a GPC-MALS method in which a multi-angle light scattering detector was connected to GPC according to the measurement conditions described below.
• GPC main unit Agilent Technologies LC1100 series Column: Showa Denko SHODEX SB806MHQ Eluent: N/3 phosphate buffer (pH 3) containing N/10 sodium nitrate Flow rate: 1.0 ml/min Detector 1: Wyatt Technology, multi-angle light scattering detector DAWN Detector 2: Showa Denko Co., Ltd., differential refractive index detector RI-101
• the acid value of the binder is preferably 50 mgKOH/g or less, more preferably in the range of 10 to 50 mgKOH/g, and even more preferably in the range of 10 to 30 mgKOH/g.
• the binder content is preferably in the range of 0.4 to 3.0% by mass, more preferably 0.4 to 1.5% by mass, relative to the total amount of yellow ink.
• the binder content is in this range, the ejection stability and storage stability of the ink are improved.
• the image fastness of the printed matter can be further improved, and the ink tends to have excellent abrasion resistance without peeling even when water is dropped onto the printed matter or when it is rubbed with a cloth containing water.
• the dispersing resin contained in the yellow ink acts as a stable dispersing means for the pigment, adsorbing to the pigment surface and stabilizing the dispersion of the pigment in water and solvent components other than water through steric hindrance or electrostatic repulsion.
• the dispersing resin exists in a state where it is adsorbed to the pigment surface or covers all or part of the pigment surface.
• the dispersing resin corresponds to the solid content of the yellow ink.
• dispersing resin examples include polyvinyl alcohols, polyvinylpyrrolidones, acrylic resins such as acrylic acid-acrylic acid ester copolymers, styrene-acrylic resins such as styrene-acrylic acid copolymers, styrene-methacrylic acid copolymers, styrene-methacrylic acid-acrylic acid ester copolymers, styrene- ⁇ -methylstyrene-acrylic acid copolymers, and styrene- ⁇ -methylstyrene-acrylic acid-acrylic acid ester copolymers, aqueous resins of styrene-maleic acid copolymers, styrene-maleic anhydride copolymers, and vinylnaphthalene-acrylic acid copolymers, and salts of the aqueous resins.
• acrylic resins such as acrylic acid-acrylic acid ester copolymers
• dispersing resin commercially available products can be used, for example, "Ajisper (registered trademark)” PB series manufactured by Ajinomoto Fine-Techno Co., Ltd., "DISPER (registered trademark) BYK” series manufactured by BYK-Chemie, "EFKA (registered trademark)” series manufactured by BASF, "SOLSPERSE (registered trademark)” series manufactured by Lubrizol Japan, “TEGO (registered trademark) Dispers” series manufactured by Evonik, etc. can be mentioned.
• a compound exemplified as polymer (G) in WO2018/190139 can also be used as the dispersing resin.
• dispersing resins may be subjected to a crosslinking treatment with a crosslinking agent after dispersing the pigment.
• the dispersing resin is preferably a styrene-acrylic resin, and more preferably a styrene-acrylic random copolymer resin.
• the weight average molecular weight (Mw) of the dispersing resin is preferably 5,000 to 50,000, and more preferably 10,000 to 30,000.
• the Mw of the dispersing resin is a value measured in terms of standard polystyrene by gel permeation chromatography (GPC), and is determined by the same measurement method as that used to measure the weight average molecular weight of the binder described above.
• the acid value of the dispersing resin is preferably 50 mgKOH/g or more, more preferably in the range of 80 to 200 mgKOH/g, and even more preferably in the range of 90 to 150 mgKOH/g.
• the content of the dispersion resin is preferably in the range of 0.5 to 2.5% by mass, and more preferably in the range of 0.8 to 2.0% by mass, based on the total amount of the yellow ink.
• the aqueous solvent constituting the yellow ink preferably contains one or more aqueous solvents having a Hansen solubility parameter (HSP) polarity term ( ⁇ P ) of 9 or less and a hydrogen bond term ( ⁇ H ) of 18 or less.
• HSP Hansen solubility parameter
• ⁇ P Hansen solubility parameter
• ⁇ H hydrogen bond term
• the content is preferably in the range of 0.1% by mass or more and less than 4.0% by mass, more preferably in the range of 0.3 to 3.5% by mass, and even more preferably in the range of 0.3 to 1.5% by mass, relative to the total amount of the yellow ink. It is believed that the inclusion of such an aqueous solvent suppresses pigment aggregation and makes it possible to increase the wettability of the pigment surface, resulting in excellent dispersion stability.
• the dispersion term ⁇ D , polar term ⁇ P , and hydrogen bond term ⁇ H have been calculated by Hansen and subsequent researchers, and are listed, for example, in Polymer Handbook (4th edition) VII-698 to 711.
• Hansen's solubility parameters for many solvents and resins have been investigated, and these solubility parameters are listed, for example, in Industrial Solvents Handbook (by Wesley L. Archer). They can also be calculated using Hansen Solubility Parameters in Practice (HSPiP) software.
• the polarity term of the HSP of the above-mentioned aqueous solvent is preferably from 3 to 9, and more preferably from 4 to 7.
• the hydrogen bond term of the HSP of the above-mentioned aqueous solvent is preferably from 3 to 18, and even more preferably from 4 to 17.5.
• the boiling point of the aqueous solvent described above under atmospheric pressure is preferably 150° C. or higher, and more preferably in the range of 150° C.
• the water contained in the yellow ink is preferably pure water or ultrapure water from which impurities such as ionic impurities have been removed as much as possible, such as ion-exchanged water, ultrafiltered water, reverse osmosis water, distilled water, etc.
• the water may be sterilized by ultraviolet irradiation, addition of hydrogen peroxide, etc.
• the water content is preferably in the range of 30 to 90% by mass, and more preferably in the range of 40 to 80% by mass, based on the total amount of the yellow ink, from the viewpoints of the property of being able to dry quickly on the surface of the recording medium after printing (drying property) and ejection stability.
• the yellow ink may contain an aqueous solvent other than the aqueous solvents described above.
• the other aqueous solvent can have the role of adjusting the viscosity of the ink, the role of further improving the ejection stability when printing by the inkjet printing method, the role of preventing the inkjet ink from drying in the ejection nozzles of the inkjet head, the role of adjusting the drying property described above, etc.
• aqueous solvents include, for example, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycols having a molecular weight of 2000 or less, propylene glycol, dipropylene glycol, tripropylene glycol, isopropylene glycol, isobutylene glycol, 1,3-propanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, 1,3-butanediol, 3-methyl-1,3-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 2-methyl-2,4-pentanediol, 1,2-hexanediol, 1,6-hexanediol, mesoerythritol, pentaerythritol, glycerin, etc.
• solvents having a boiling point in the range of 180 to 300° C. are preferred, and propylene glycol or glycerin are more preferred.
• propylene glycol and glycerin are used in combination as other aqueous solvents, aggregation and precipitation of the pigment in the ink are less likely to occur, and the viscosity can be adjusted to a desired level while maintaining dispersion stability, which is preferable from the standpoint of improving the ejection stability when printing by an inkjet printing method and of making it easier to improve the drying properties of the ink after printing.
• the content of the other aqueous solvent is preferably in the range of 0.1 to 35% by mass, and more preferably in the range of 15 to 35% by mass, based on the total amount of the yellow ink.
• the pigment contained in the cyan ink is C.I. Pigment Blue 15:3.
• the content of C.I. Pigment Blue 15:3 relative to the total amount of the cyan ink is more than 2.5% by mass and less than 5.5% by mass, more preferably in the range of 2.7 to 5.3% by mass, and even more preferably in the range of 3.0 to 4.0% by mass.
• the volume average particle diameter of C.I. Pigment Blue 15:3 is 80 to 100 nm, and more preferably 85 to 95 nm.
• the volume average particle diameter of C.I. Pigment Blue 15:3 is determined by a dynamic light scattering method, a laser diffraction method, or the like, which are general measurements of pigment dispersion particles, and an example of the measurement method is the same as the measurement method of the volume average particle diameter of C.I. Pigment Yellow 74 described above.
• the binder contained in the cyan ink is the same as the binder contained in the yellow ink, and the details are as described above.
• the content of the binder in the cyan ink is preferably in the range of 0.4 to 3.0% by mass, more preferably in the range of 0.4 to 1.5% by mass, based on the total amount of the cyan ink.
• the binder content is in the above range, the ejection stability and storage stability of the ink are improved.
• the image fastness of the printed matter can be further improved, and even when water is dropped on the printed matter or when the printed matter is rubbed with a cloth containing water, the ink does not peel off, and tends to have excellent abrasion resistance.
• the dispersion resin contained in the cyan ink is the same as the dispersion resin contained in the yellow ink, and the details are as described above.
• the content of the dispersion resin in the cyan ink is preferably in the range of 0.3 to 2.5% by mass, and more preferably in the range of 0.5 to 2.0% by mass, based on the total amount of the cyan ink.
• the aqueous solvent contained in the cyan ink is the same as the aqueous solvent contained in the yellow ink, and the details are as described above.
• the suitable contents of the aqueous solvent and water are also the same as those of the yellow ink.
• the ink set of the present invention when the content of the pigment (C.I. Pigment Yellow 74) in the yellow ink and the content of the pigment (C.I. Pigment Blue 15:3) in the cyan ink both satisfy the above-mentioned ranges, the pigment dispersion stability, ejection stability, storage stability, and sufficient print density are ensured, while the chroma of the primary and secondary colors of the obtained printed matter is excellent.
• the chroma (c * ) of green in particular can be improved without decreasing the chroma of blue and red, which are the secondary colors.
• the ink set of the present invention may further include a magenta ink.
• the pigment contained in the magenta ink is a solid solution pigment consisting of C.I. Pigment Red 122 and C.I. Pigment Violet 19. Commercially available products can be used for each of these pigments.
• the mass ratio of C.I. Pigment Red 122 to C.I. Pigment Violet 19 (C.I. Pigment Red 122/C.I. Pigment Violet 19) is 4/1 to 1/1, and more preferably in the range of 3.5/1 to 2.5/1.
• the mass ratio of C.I. Pigment Red 122 to C.I. Pigment Violet 19 is within the above-mentioned range, the chroma of red is excellent.
• the method for producing the solid solution pigment is not particularly limited, and known methods disclosed in JP-A-11-49998, JP-A-2000-319534, JP-A-2003-253150, etc. can be applied.
• the solid solution pigment means a pigment that exists as a mixed crystal (crystallized in a mixed state) of multiple pigment molecules, and is different from a simple mixture of two or more pigments. Whether or not a solid solution pigment has been formed can be confirmed by X-ray diffraction analysis. In the case of a mixture of two pigments, the X-ray diffraction pattern obtained is equivalent to the superposition of the X-ray diffraction patterns of the respective pigments, and the peak intensity is proportional to the blending ratio. On the other hand, when a solid solution pigment is formed, the formed crystals show their own diffraction pattern.
• the content of the solid solution pigment relative to the total amount of the magenta ink is from 4.0 to 10.0% by mass, and preferably from 5.0 to 9.0% by mass.
• the volume average particle diameter of the solid solution pigment is 80 to 150 nm, and more preferably 90 to 130 nm.
• the volume average particle diameter of the solid solution pigment is determined by a general measurement method for pigment dispersion particles, such as dynamic light scattering method or laser diffraction method, and an example of the measurement method is the same as the measurement method for the volume average particle diameter of C.I. Pigment Yellow 74 described above.
• the binder contained in the magenta ink is the same as the binder contained in the yellow ink and the cyan ink, and the details are as described above.
• the content of the binder in the magenta ink is preferably in the range of 0.4 to 3.0% by mass, more preferably in the range of 0.4 to 1.5% by mass, based on the total amount of the magenta ink.
• the binder content is in the above range, the ejection stability and storage stability of the ink are improved.
• the image fastness of the printed matter can be further improved, and even when water is dropped on the printed matter or when the printed matter is rubbed with a cloth containing water, the ink tends to not peel off and has excellent abrasion resistance.
• the dispersion resin contained in the magenta ink is the same as the dispersion resin contained in the yellow ink and the cyan ink, and the details are as described above.
• the content of the dispersion resin in the magenta ink is preferably in the range of 0.3 to 2.5 mass % relative to the total amount of the magenta ink, and more preferably in the range of 0.5 to 2.0 mass %.
• the aqueous solvent contained in the magenta ink is the same as the aqueous solvent contained in the yellow ink and the cyan ink, and the details are as described above.
• the suitable contents of the aqueous solvent and water are also the same as those of the yellow ink and the cyan ink.
• the ink set of the present invention further comprises a magenta ink
• the ratio of the concentration of the solid solution pigment contained in the magenta ink to the concentration of the pigment contained in the cyan ink is preferably 1.5 or more, and more preferably in the range of 1.5 to 3.0.
• magenta/cyan concentration ratio is within the above range, the secondary colors tend to have an excellent balance of saturation.
• the ink set of the present invention may further include a black ink.
• the coloring material of the black ink is not particularly limited.
• an inorganic pigment for example, iron oxide or carbon black produced by a contact method, a furnace method, a thermal method, or the like can be used.
• black pigments include C.I. Pigment Black 1, 6, 7, 8, 10, 26, 27, and 28, and specific examples of commercially available products include No. 2300, No. 2200B, No. 900, No. 960, No. 980, No. 33, No. 40, No. 45, No. 45L, and No. 50L manufactured by Mitsubishi Chemical Corporation.
• a self-dispersing pigment may be used in which a dispersibility-imparting group (hydrophilic functional group and/or a salt thereof) or an active species having a dispersibility-imparting group is bonded (grafted) to the surface of the pigment directly or indirectly via an alkyl group, an alkyl ether group, an aryl group, or the like.
• Examples of commercially available self-dispersion pigments that are manufactured industrially include Microjet CW-1, BONJET BLACK CW-1, BONJET BLACK CW-1S, BONJET BLACK CW-2, and BONJET BLACK CW-3 (all trade names; manufactured by Orient Chemical Industries Co., Ltd.), CAB-O-JET 200 and CAB-O-JET 300 (all trade names; manufactured by CABOT Corporation), SENSIJET Black SDP100, SENSIJET Black SDP1000, and SENSIJET Black SDP2000 (all trade names; manufactured by Sensient Technologies).
• the above-mentioned dispersing resin is not necessary.
• Each ink constituting the ink set of the present invention may further contain a surfactant.
• a surfactant When the ink contains a surfactant, the ink discharged from the nozzle of the inkjet head easily wets and spreads on the surface after landing on the print medium, which makes it easier to prevent printing defects. In addition, the surface tension of the ink is reduced, which makes it easier to improve the leveling property.
• the surfactant include anionic surfactants, nonionic surfactants, cationic surfactants, and amphoteric surfactants, with anionic surfactants and nonionic surfactants being preferred.
• anionic surfactant examples include alkylbenzenesulfonates, alkylphenylsulfonates, alkylnaphthalenesulfonates, higher fatty acid salts, sulfates or sulfonates of higher fatty acid esters, sulfates or sulfonates of higher alcohol ethers, higher alkyl sulfosuccinates, polyoxyethylene alkyl ether carboxylates, sulfates of polyoxyethylene alkyl ethers, phosphates or alkyl phosphates.
• nonionic surfactant examples include glycol surfactants, silicone surfactants, fluorine surfactants, and acetylene diol surfactants.
• glycol surfactants include polyoxyethylene alkyl ethers, polyoxyethylene alkylaryl ethers, polyoxyethylene fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene sorbitol fatty acid esters, polyoxyethylene glycerin fatty acid esters, polyglycerin fatty acid esters, polyoxyethylene alkylamines, polyoxyethylene fatty acid amides, and polyoxyethylene-polyoxypropylene block copolymers.
• silicone surfactants include polysiloxane compounds, polyether-modified organosiloxanes, etc.
• examples of commercially available silicone surfactants include the "BYK (registered trademark)" series manufactured by BYK Japan KK and the “KF” series manufactured by Shin-Etsu Chemical Co., Ltd.
• fluorosurfactants include perfluoroalkyl carboxylates, perfluoroalkyl sulfonates, oxyethylene perfluoroalkyl ethers, perfluoroalkyl phosphates, perfluoroalkyl betaines, perfluoroalkyl amine oxides, etc.
• fluorosurfactants examples include the "Megafac (registered trademark)” series manufactured by DIC Corporation, the “Ftergent (registered trademark)” series manufactured by Neos Corporation, and the “Novec (registered trademark)” series manufactured by Sumitomo 3M Limited.
• Acetylene diol surfactants are surfactants that have a carbon-carbon triple bond in the molecule, and examples of such surfactants include acetylenic diol (having an acetylenic bond and two hydroxyl groups in the same molecule) surfactants, and surfactants in which alkylene oxides such as ethylene oxide and propylene oxide are added to acetylenic diol.
• surfactants examples include alkylene oxide adducts of 2,4,7,9-tetramethyl-5-decyne-4,7-diol and 2,4,7,9-tetramethyl-5-decyne-4,7-diol, and alkylene oxide adducts of 2,4-dimethyl-5-decyne-4-ol and 2,4-dimethyl-5-decyne-4-ol.
• acetylenic diol surfactants include the "Surfynol (registered trademark)” series manufactured by Evonik, the “Olfine (registered trademark)” series manufactured by Nissin Chemical Industry Co., Ltd., and the “Acetylenol (registered trademark)” series manufactured by Kawaken Fine Chemical Co., Ltd.
• acetylene diol surfactants are more preferred from the viewpoint of easily preventing the occurrence of printing defects.
• the HLB value of the surfactant is preferably 15 or less, more preferably 10 or less.
• the HLB value of the surfactant is preferably 2.5 or more, more preferably 3.5 or more.
• the HLB value of the surfactant is more preferably in the range of 3.5 to 9.
• the content thereof is preferably in the range of 0.01 to 5 mass %, and more preferably in the range of 0.1 to 2 mass %, relative to the total amount of each ink.
• the surfactant may be used alone or in combination of two or more.
• each ink constituting the ink set of the present invention may further contain other additives such as pH adjusters, preservatives, polyolefin wax, antioxidants, viscosity adjusters, wetting agents (drying inhibitors), penetrating agents, chelating agents, plasticizers, and UV absorbers, as necessary.
• additives such as pH adjusters, preservatives, polyolefin wax, antioxidants, viscosity adjusters, wetting agents (drying inhibitors), penetrating agents, chelating agents, plasticizers, and UV absorbers, as necessary.
• pH adjusters include potassium dihydrogen phosphate, disodium hydrogen phosphate, sodium hydroxide, lithium hydroxide, potassium hydroxide, ammonia, diethanolamine, triethanolamine, triisopropanolamine, potassium carbonate, sodium carbonate, and sodium hydrogen carbonate.
• preservatives include sodium benzoate, sodium pentachlorophenol, sodium 2-pyridinethiol-1-oxide, sodium sorbate, sodium dehydroacetate, 1,2-dibenzisothiazolin-3-one, etc.
• preservatives such as "ACTICIDE (registered trademark) B20” (product name, manufactured by Thor Japan Co., Ltd.) and “Proxel (registered trademark) GXL” (product name, manufactured by SC Johnson Co., Ltd.).
• polyolefin waxes examples include waxes or copolymers produced from olefins such as ethylene, propylene, butylene, or derivatives thereof, such as polyethylene wax, polypropylene wax, polybutylene wax, and modified waxes thereof.
• oxidized polyethylene wax obtained by oxidatively modifying polyethylene wax is preferred from the viewpoint of improving image fastness of printed matter.
• Commercially available polyolefin waxes may be used, such as the "AQUACER (registered trademark)" series (manufactured by BYK Japan).
• antioxidant include phenol-based antioxidants, amine-based antioxidants, phosphorus-based antioxidants, and sulfur-based antioxidants.
• each ink constituting the ink set of the present invention further contains other additives
• the amount of such additives is preferably in the range of 0.01 to 5% by mass, and more preferably in the range of 0.02 to 3% by mass, based on the total amount of each ink.
• the method for preparing each ink constituting the ink set of the present invention is not particularly limited, and the inks can be prepared by mixing the above-mentioned components.
• the above-mentioned components may be mixed all at once or sequentially.
• the binder may be dissolved or dispersed in water or another solvent and then mixed.
• the pigment may be dispersed together with a dispersing resin in water or another solvent and then mixed.
• a dispersing machine such as a bead mill, ultrasonic homogenizer, high-pressure homogenizer, paint shaker, ball mill, roll mill, sand mill, sand grinder, Dyno Mill, Dispermat, SC Mill, Nanomizer, etc. can be used.
• the viscosity at 25°C of each ink constituting the ink set of the present invention is preferably in the range of 2.0 to 12.0 mPa ⁇ s, more preferably in the range of 2.5 to 5.0 mPa ⁇ s, and even more preferably in the range of 3.0 to 4.0 mPa ⁇ s, from the viewpoints of providing excellent storage stability and ejection stability, and of reducing deviation in the landing position on a recording medium caused by deflection of ink droplets when used in an inkjet recording system, and of easily suppressing the occurrence of streaks in printed matter.
• the viscosity of the ink is a value measured, for example, using a cone-plate type rotational viscometer equivalent to an E-type viscometer under the following conditions.
• the surface tension at 25°C of each ink constituting the ink set of the present invention is preferably 20 mN/m or more, more preferably 25 mN/m or more. Such surface tension is preferably 40 mN/m or less, more preferably 35 mN/m or less. If the surface tension is within this range, when used in an inkjet recording method, the ink has good wettability on the surface of the recording medium from the ejected droplets, and tends to have sufficient wetting and spreading after landing.
• the pH at 25°C of each ink constituting the ink set of the present invention is preferably 7.0 to 11.0, and more preferably 7.5 to 10.5, from the viewpoint of improving the storage stability and ejection stability of the ink, improving the wetting spread, print density, and image fastness when printed on a recording medium, and from the viewpoint of suppressing deterioration of the components constituting the ink application or ejection device (ink ejection port, ink flow path, etc.).
• the ink set of the present invention can be applied to various ink jet recording methods such as thermal jet type, piezoelectric type, continuous ink jet type, roller application type, spray application type, and the like, and to recording devices using these recording methods.
• Examples of recording media to which droplets of the ink set of the present invention are deposited include plain paper, cast glossy paper in which a coating is applied to the surface of plain paper and an ink-receiving layer with excellent surface gloss is formed by a casting method to impart gloss to the surface, and polymer-coated glossy paper in which an inkjet recording layer containing a resin as a main component is formed.
• the present invention has been described above, but the present invention is not limited to the configuration of the above-mentioned embodiment.
• the ink set of the present invention may have any other configuration in addition to the configuration of the above-mentioned embodiment, or may be replaced with any configuration that exhibits a similar function.
• Binder 1 Styrene-acrylic resin (MFT: 36° C., volume average particle size 60 nm, Mw 500,000, acid value 20 mg KOH/g, manufactured by DIC Corporation)
• Styrene-acrylic random copolymer resin Mw 18,000, acid value 110 mgKOH/g
• Pigment Dispersion Y (Yellow)> 150 g of yellow pigment, 60 g of dispersion resin, 75 g of PG, and 19.4 g of 34 mass% potassium hydroxide aqueous solution were charged into an intensive mixer (manufactured by Nippon Eirich Co., Ltd.) with a capacity of 1.0 L, and kneaded for 25 minutes at a rotor peripheral speed of 2.94 m/s and a pan peripheral speed of 1 m/s.
• an intensive mixer manufactured by Nippon Eirich Co., Ltd.
• Pigment dispersion C (Cyan)> Pigment dispersion C (pigment concentration: 20% by mass) was prepared in the same manner as for pigment dispersion Y, except that a cyan pigment was used instead of the yellow pigment.
• Pigment dispersion M (Magenta)> Pigment dispersion M (pigment concentration: 20% by mass) was prepared in the same manner as pigment dispersion Y, except that a magenta pigment was used instead of the yellow pigment.
• Abrasion resistance (coated paper)
• the ink sets of each Example and Comparative Example were each loaded into an Epson inkjet printer (PX-S740), and full solid printing was performed on coated paper (product name "SWORD iJET (registered trademark) 4.3 Gloss", manufactured by Mitsubishi Paper Mills, basis weight 104.7 g/m 2 ) to obtain an ink coating film.
• the obtained coating film was dried at room temperature (25° C.) for 12 hours.
• a Gakushin type friction tester RT-300 manufactured by Daiei Scientific Instruments Manufacturing Co., Ltd.
• the dried coating film was rubbed 50 times at a load of 100 g/cm 2 using the same paper as the printing substrate as a friction element.
• the degree of peeling of the coating film was visually observed, and the abrasion resistance (image fastness) was evaluated according to the following criteria.
• ⁇ Evaluation criteria> ⁇ : No scratches were observed on the printed matter, or only slight scratches were observed. ⁇ : Many scratches were observed on the printed matter, and dark coloring was observed in parts of the friction piece paper.
• the ink set satisfying the requirements of the present invention provides a good balance of the chroma of the secondary colors red, green and blue, and can particularly improve the chroma of green.
• Comparative Examples 1 and 2 in which the yellow ink content and the cyan ink pigment content do not satisfy the requirements of the present invention, both have poor green saturation.
• Comparative Example 1 in which the cyan ink pigment content is lower than the requirements of the present invention, also has low blue saturation, while Comparative Example 2, in which the cyan ink pigment content is higher than the requirements of the present invention, has low red saturation.
• Comparative Example 3 which does not contain a binder that satisfies the requirements of the present invention, reduces the abrasion resistance of the printed matter.
• aggregation of pigments in the ink is suppressed and dispersion stability is improved, making it possible to achieve a balance between ink density (OD) and improved saturation in printed matter.
• the ink set of the present invention has improved saturation of primary and secondary colors, especially green saturation, and has excellent abrasion resistance of printed images. Therefore, it is particularly useful as an inkjet ink for industrial inkjet printers.

Landscapes

• Chemical & Material Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Wood Science & Technology (AREA)
• Organic Chemistry (AREA)
• Inks, Pencil-Leads, Or Crayons (AREA)
• Ink Jet (AREA)

Priority Applications (4)

Applications Claiming Priority (2)

Publications (1)

Family

ID=92146564

Family Applications (1)

Country Status (4)

Citations (10)

Family Cites Families (7)

• 2024
  • 2024-01-18 JP JP2024522665A patent/JPWO2024162011A1/ja active Pending
  • 2024-01-18 WO PCT/JP2024/001187 patent/WO2024162011A1/ja not_active Ceased
  • 2024-01-18 EP EP24749965.0A patent/EP4610318A4/en active Pending
  • 2024-01-18 CN CN202480004970.0A patent/CN120239731A/zh active Pending
  • 2024-10-03 JP JP2024174256A patent/JP2025000970A/ja active Pending

Patent Citations (10)

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events