Ink composition and ink jet recording method

Abstract

Provided is an ink composition containing a water-insoluble colorant, a dispersant, a resin A, a resin B, and water, the resin A being a resin obtained by polymerizing at least a C1-C4 alkyl methacrylate and a C2-C6 alkyl acrylate, and the resin B being a resin obtained by polymerizing at least a styrene monomer and divinyl benzene. In addition, the present invention provides an ink jet recording method using the ink composition, a recording medium to which the ink composition is adhered, and an ink jet printer provided with a container filled with the ink composition.

Description

Technical Field

[0001] The present invention relates to an ink composition, an inkjet recording method using the ink composition, a recording medium to which the ink composition is attached, and an inkjet printer including a container filled with the ink composition. Background Art

[0002] An inkjet printing method using an inkjet printer is known as one of the representative color printing methods. This inkjet method is a method of printing by generating droplets of ink and attaching them to a recording medium such as paper.

[0003] In recent years, inkjet printing methods are developing as industrial applications. The colorants contained in inkjet inks can be roughly divided into water-soluble colorants and water-insoluble colorants. Among them, water-insoluble colorants represented by pigments are generally excellent in various fastnesses compared to water-soluble colorants. Therefore, industrial inkjet inks often contain water-insoluble colorants. But on the other hand, water-insoluble colorants are generally inferior in color rendering compared to water-soluble colorants. Based on such a background, it is strongly desired to have industrial inks containing water-insoluble colorants and excellent in color rendering and glossiness.

[0004] As substrates used for industrial purposes, various papers, fibers, films, etc. can be cited, and there is a tendency to diversify. Among these substrates, there are many substrates that do not absorb ink or substrates that are difficult to absorb ink (hereinafter, also collectively referred to as "non-ink and difficult to absorb substrates"). As inks used when printing on such non-ink and difficult to absorb substrates, non-aqueous solvent inks, curable inks, etc. are known.

[0005] However, non-aqueous solvent inks and curable inks have high contents of volatile organic compounds (VOCs), which poses a problem of safety for the natural environment, organisms, etc. Therefore, there is a strong desire for water-based inks that can also be used for printing on non-poorly absorbent substrates. Water-based inks have a composition that minimizes VOCs and contains water-insoluble colorants and dispersants. In addition, in order to improve friction resistance, solvent resistance, etc., water-based inks usually also contain resins, waxes, etc. Such water-based inks have a high content of solid components and are therefore very easy to dry. In addition, solid matter is easily produced due to drying. When printing on non-poorly absorbent substrates, a film is formed by the solid components, thereby improving the fixability and friction resistance on the substrate. Therefore, the stronger the film formed by the solid components, the more ideal it is as a printed matter.

[0006] In addition, when printing on a substrate that is not or poorly absorbent of ink, in addition to fixability and friction resistance to the substrate, scratch resistance is also required. Since a substrate that is not or poorly absorbent of ink lacks ink absorption, it is generally disadvantageous in terms of fixability and friction resistance. Therefore, it is desired to improve scratch resistance by making the film obtained from the solid component more solid.

[0007] On the other hand, the drying of ink also occurs during long-term storage, storage under high temperature or low humidity environment, etc. If the ink filled in the inkjet printer dries, solid matter will be generated in the nozzle or ink flow path of the inkjet head, which becomes the cause of clogging. If clogging occurs in the inkjet head like this, the ink cannot be ejected stably, resulting in problems such as reduced image quality of the recorded image. In addition, the frequency of the inkjet head itself becoming unusable also increases, forming a big problem. Therefore, it is also strongly required that even if solid matter is generated in the inkjet head, it can be easily cleaned. However, since the above-mentioned fixability, friction resistance and scratch resistance achieved by the formation of the film are opposite to the performance that can be easily cleaned, water-based ink that meets these two effects has not yet been proposed. Based on these reasons, a method of preventing the drying of ink by equipping the nozzle part of the industrial inkjet head with a cap component has been proposed. However, even so, it is still extremely difficult to completely prevent the drying of ink.

[0008] Patent Documents 1 to 8 describe resin emulsions or resin particle dispersions, and ink compositions containing the same.

[0009] Prior art literature

[0010] Patent Literature

[0011] Patent Document 1: International Publication No. 2015 / 147192

[0012] Patent Document 2: Japanese Patent Application Publication No. 2000-34432

[0013] Patent Document 3: Japanese Patent Application Publication No. 2000-336292

[0014] Patent Document 4: Japanese Patent Application Publication No. 2009-191133

[0015] Patent Document 5: Japanese Patent Application Publication No. 2013-213210

[0016] Patent Document 6: Japanese Patent Application Publication No. 2017-141388

[0017] Patent Document 7: International Publication No. 2021 / 006211

[0018] Patent Document 8: Japanese Patent No. 6833339

[0019] Patent Document 9: International Publication No. 2013 / 115071 Summary of the invention

[0020] Problems to be solved by the invention

[0021] The present invention aims to provide an ink composition having good color development and glossiness and excellent scratch resistance and washability, an inkjet recording method using the ink composition, a recording medium having the ink composition attached thereto, and an inkjet printer having a container filled with the ink composition.

[0022] Means for solving problems

[0023] Specific means for solving the above-mentioned problems include the following embodiments.

[0024] <1> An ink composition comprising a water-insoluble colorant, a dispersant, a resin A, a resin B and water,

[0025] The resin A is a resin obtained by polymerizing at least a C1-C4 alkyl methacrylate and a C2-C6 alkyl acrylate.

[0026] The resin B is a resin obtained by polymerizing at least a styrene-based monomer and divinylbenzene.

[0027] <2> like <1> In the ink composition, each of the resin A and the resin B is a resin obtained by polymerizing a reactive emulsifier having a radical polymerizable double bond in a molecule.

[0028] <3> like <2> In the ink composition, the reactive emulsifier is a reactive emulsifier having an anionic group in the molecule.

[0029] <4> like <3> In the ink composition, the anionic group is a salt of a sulfate ester group.

[0030] <5> like <1> ~ <4> The ink composition described above further contains a water-soluble organic solvent.

[0031] <6> Inkjet recording method, wherein an inkjet printer is used to record a <1> ~ <4> The recording is performed by ejecting droplets of the ink composition described in any one of the above-described methods and attaching them to a recording medium.

[0032] <7> like <6> In the inkjet recording method, the recording medium is a recording medium having an ink receiving layer.

[0033] <8> like <6> In the inkjet recording method, the recording medium is a recording medium without an ink receiving layer.

[0034] <9> like <6> ~ <8> The inkjet recording method described in any one of the above, wherein the inkjet printer is a line head type inkjet printer.

[0035] <10> A recording medium having <1> ~ <4> The ink composition described above.

[0036] <11> like <10> The recording medium is selected from a recording medium having an ink receiving layer and a recording medium not having an ink receiving layer.

[0037] <12> Inkjet printer having a <1> ~ <4> A container for the ink composition described above.

[0038] <13> like <12> The inkjet printer is a linear head type inkjet printer.

[0039] Effects of the Invention

[0040] According to the present invention, there can be provided an ink composition having good color development and glossiness and excellent scratch resistance and washability, an inkjet recording method using the ink composition, a recording medium having the ink composition attached thereto, and an inkjet printer having a container filled with the ink composition. DETAILED DESCRIPTION

[0041] <Ink Composition>

[0042] The ink composition involved in this embodiment contains a water-insoluble colorant, a dispersant, a resin A, a resin B, and water, wherein the resin A is a resin obtained by polymerizing at least a C1-C4 alkyl methacrylate and a C2-C6 alkyl acrylate, and the resin B is a resin obtained by polymerizing at least a styrene monomer and divinylbenzene. The components contained in the ink composition involved in this embodiment are described in detail below. It should be noted that each of the components described below can be used alone or in combination of two or more.

[0043] [Water-insoluble colorant]

[0044] The water-insoluble colorant is a colorant having a solubility in water at 25° C. of usually 3 g / L or less, preferably 2 g / L or less, and more preferably 1 g / L or less.

[0045] Examples of water-insoluble colorants include pigments, disperse dyes, and solvent dyes. Representative examples thereof include colorants selected from CI pigments, CI disperse dyes, and CI solvent dyes.

[0046] Examples of the pigment include inorganic pigments, organic pigments, and extender pigments.

[0047] Examples of the inorganic pigment include carbon black, metal oxides, metal hydroxides, metal sulfides, metal ferrocyanides, and metal chlorides.

[0048] Examples of carbon black include thermal black, acetylene black, oil furnace black, gas furnace black, lamp black, gas black, and channel black. Among these, furnace black, lamp black, acetylene black, and channel black are preferred. Various types of carbon black can be easily obtained from Columbia Carbon Co., Ltd., Cabot Corporation, Degussa Corporation, Mitsubishi Chemical Corporation, and the like.

[0049] Examples of the organic pigment include soluble azo pigments, insoluble azo pigments, insoluble disazo pigments, condensed azo pigments, phthalocyanine pigments, quinacridone pigments, isoindolinone pigments, dioxazine pigments, perylene pigments, perindole pigments, thioindigo pigments, anthraquinone pigments, and quinophthalone pigments.

[0050] Specific examples of organic pigments include CI Pigment Yellow 1, 2, 3, 12, 13, 14, 16, 17, 24, 55, 73, 74, 75, 83, 93, 94, 95, 97, 98, 108, 114, 128, 129, 138, 139, 150, 151, 154, 180, 185, 193, 199, 202; CI Pigment Red 5, 7, 12, 48, 48:1, 57, 88, 112, 122, 123, 146, 149, 150, 166, 167; 8, 177, 178, 179, 184, 185, 202, 206, 207, 254, 255, 257, 260, 264, 269, 272; CI Pigment Blue 1, 2, 3, 15, 15:1, 15:2, 15:3, 15:4, 15:6, 16, 22, 25, 60, 66, 80; CI Pigment Violet 19, 23, 29, 37, 38, 50; CI Pigment Orange 13, 16, 68, 69, 71, 73; CI Pigment Green 7, 36, 54; CI Pigment Black 1; and so on.

[0051] Examples of the extender pigment include silicon dioxide, calcium carbonate, talc, clay, barium sulfate, white carbon, etc. These extender pigments are often used in combination with an inorganic pigment or an organic pigment for the purpose of improving the fluidity of the powder.

[0052] In addition, as a water-insoluble colorant, a self-dispersible pigment obtained by chemically treating the surface of the pigment particles to impart self-dispersibility may be used.

[0053] Examples of disperse dyes include CI Disperse Yellow 9, 23, 33, 42, 49, 54, 58, 60, 64, 66, 71, 76, 79, 83, 86, 90, 93, 99, 114, 116, 119, 122, 126, 149, 160, 163, 165, 180, 183, 186, 198, 200, 211, 224, 226, 227, 231, and 237; CI Disperse Red 60, 73, 88, 91, 92, 111, 127, 131, 143, 145, 146, 152, 153, 154, 167, 179, 191, 192, 206, 218, 227, 231, and 237; 21, 258, 283; CI Disperse Orange 9, 25, 29, 30, 31, 32, 37, 38, 42, 44, 45, 53, 54, 55, 56, 61, 71, 73, 76, 80, 96, 97; CI Disperse Violet 25, 27, 28, 54, 57, 60, 73, 77, 79, 79:1; CI Disperse Blue 27, 56, 60, 79:1, 87, 143, 165, 165:1, 165:2, 181, 185, 197, 202, 225, 257, 266, 267, 281, 341, 353, 354, 358, 364, 365, 368; and so on.

[0054] In addition, as the water-insoluble colorant, a water-insoluble copolymer colored with a water-soluble colorant can also be mentioned. As the water-insoluble copolymer, for example, polyester, a dispersant and a resin described later can be mentioned.

[0055] As water-soluble colorants, for example, direct dyes, acid dyes, food dyes, basic dyes, reactive dyes, vat dyes and soluble vat dyes can be mentioned. As representative colorants, dyes selected from CI direct dyes (CI Direct), CI acid dyes (CI Acid), CI food dyes (CI Food), CI basic dyes (CI Basic), CI reactive dyes (CI Reactive), CI vat dyes (CI Vat) and CI soluble vat dyes (CI Solubilised Vat) can be mentioned.

[0056] It should be noted that the copolymer in the water-insoluble copolymer colored with a water-soluble colorant and the copolymer used as, for example, a dispersant may be the same copolymer or different copolymers. When the same copolymer is used, the copolymer colored with a water-soluble colorant and the copolymer not colored with a water-soluble colorant are respectively equivalent to the water-insoluble colorant and the dispersant.

[0057] Among these water-insoluble colorants, pigments are preferred, and pigments selected from CI pigments are more preferred.

[0058] The content of the water-insoluble colorant in the total mass of the ink composition according to the present embodiment is usually 1 to 30% by mass, preferably 1 to 15% by mass, and more preferably 2 to 10% by mass.

[0059] [Dispersant]

[0060] Examples of dispersants include copolymers composed of at least two monomers selected from the following monomers (preferably at least one of which is a hydrophilic monomer): styrene and its derivatives; vinylnaphthalene and its derivatives; aliphatic alcohol esters of α,β-ethylenically unsaturated carboxylic acids; (meth)acrylic acid and its derivatives; maleic acid and its derivatives; itaconic acid and its derivatives; fumaric acid and its derivatives; vinyl acetate, vinyl alcohol, vinyl pyrrolidone, acrylamide and their derivatives; etc. Examples of hydrophilic monomers include monomers having residual carboxyl groups after polymerization, such as acrylic acid and methacrylic acid.

[0061] As such copolymers, for example, styrene-(meth)acrylic acid copolymers, styrene-(meth)acrylic acid-(meth)acrylic acid ester copolymers, (meth)acrylic acid ester-(meth)acrylic acid copolymers, polyethylene glycol (meth)acrylic acid ester-(meth)acrylic acid copolymers, styrene-maleic acid copolymers, etc. can be cited. Among these, preferably styrene-(meth)acrylic acid copolymers, styrene-(meth)acrylic acid-(meth)acrylic acid ester copolymers, (meth)acrylic acid ester-(meth)acrylic acid copolymers, and polyethylene glycol (meth)acrylic acid ester-(meth)acrylic acid copolymers, more preferably styrene-(meth)acrylic acid copolymers, styrene-(meth)acrylic acid-(meth)acrylic acid ester copolymers, and (meth)acrylic acid ester-(meth)acrylic acid copolymers, further preferably (meth)acrylic acid ester-(meth)acrylic acid copolymers, particularly preferably methacrylate-methacrylic acid copolymers. As the type of copolymer, for example, block copolymers, random copolymers, graft copolymers, etc. can be cited. These copolymers can be in the form of salts.

[0062] In addition, in this specification, the term "(meth)acryl-" is used to include both "acryl-" and "methacryl-." The same applies to "(meth)acrylate" and the like.

[0063] The dispersant may be synthesized or obtained as a commercial product.

[0064] As the copolymer obtained by synthesis, preferably, for example, the AB block copolymer disclosed in International Publication No. 2013 / 115071 can be cited. The monomer constituting the A block of the AB block polymer disclosed in International Publication No. 2013 / 115071 is at least one monomer selected from (meth)acrylic acid, and linear or branched C4 alkyl (meth)acrylate, preferably at least one monomer selected from methacrylic acid and n-butyl methacrylate, and more preferably a combination of these two monomers. In addition, the monomer constituting the B block of the AB block polymer disclosed in International Publication No. 2013 / 115071 is at least one monomer selected from benzyl methacrylate and benzyl acrylate, preferably benzyl methacrylate. As a specific example of the AB block polymer, the block copolymer disclosed in Synthesis Examples 3 to 8 of International Publication No. 2013 / 115071 can be cited.

[0065] Examples of commercially available dispersants include Joncyrl 62, 67, 68, 678, and 687 (styrene-acrylic acid copolymers manufactured by BASF); Mowinyl S-100A (modified vinyl acetate copolymer manufactured by Japan Coating Resin Corporation); Jurymer AT-210 (polyacrylate copolymer manufactured by Toagosei Co., Ltd.); and the like.

[0066] The mass average molecular weight (Mw) of the dispersant is generally 3000 to 50000, preferably 7000 to 25000. The mass average molecular weight of the dispersant can be measured by gel permeation chromatography (GPC method). Specifically, HLC-8320GPC (TOSOH (strain) system) can be used as a GPC device, 2 TSK gel Super Multipore HZ-H (TOSOH (strain) system, inner diameter 4.6mm × 15cm) can be used as a column, tetrahydrofuran is used as an eluent, and TSK Standard (TOSOH (strain) system) is used as a standard sample to measure.

[0067] The acid value of the dispersant is usually 50 to 300 mgKOH / g, preferably 80 to 275 mgKOH / g, and more preferably 80 to 250 mgKOH / g.

[0068] The dispersant can be used in a state of being mixed with the water-insoluble colorant. Alternatively, it can also be used in a state of coating a part or all of the surface of the water-insoluble colorant with the dispersant. Alternatively, these two states can also be used in combination.

[0069] The ink composition according to the present embodiment is preferably prepared by preparing a dispersion containing a water-insoluble colorant and a dispersant and then mixing the dispersion with other components. A known method can be used to prepare the dispersion.

[0070] As an example of a method for preparing a dispersion, a phase inversion emulsification method can be cited. That is, a dispersant is dissolved in an organic solvent such as 2-butanone, and an aqueous solution of a neutralizing agent is added to prepare an emulsion. A water-insoluble colorant is added to the obtained emulsion and a dispersion treatment is performed. From the liquid obtained as described above, the organic solvent and a portion of the water are distilled off under reduced pressure, thereby obtaining the target dispersion. The dispersion treatment can be performed using, for example, a sand mill (bead mill), a roller mill, a ball mill, a paint oscillator, an ultrasonic disperser, a microfluidizer, and the like. As an example, when using a sand mill, beads with a particle size of about 0.01 to 1 mm can be used, and the filling rate of the beads can be appropriately set for dispersion treatment. The dispersion obtained as described above can also be filtered, centrifuged, and the like. Through this operation, the particle size of the particles contained in the dispersion can be made consistent. When foaming occurs during the preparation of the dispersion, a very small amount of a known defoaming agent such as a silicone-based or acetylene glycol-based defoamer can be added.

[0071] Examples of methods for preparing dispersions other than those mentioned above include acid precipitation, interfacial polymerization, in-situ polymerization, liquid solidification coating, coacervation (phase separation), liquid drying, melt dispersion cooling, gas suspension coating, and spray drying.

[0072] Among these preparation methods, the phase inversion emulsification method, the acid precipitation method and the interfacial polymerization method are preferred.

[0073] The average particle size (D50) of the water-insoluble colorant in the dispersion is usually less than 300nm, preferably 30 to 280nm, more preferably 40 to 270nm, and further preferably 50 to 250nm. In addition, the average particle size (D90) of the water-insoluble colorant is usually less than 400nm, preferably less than 350nm, and more preferably less than 300nm. The lower limit is preferably more than 100nm. In addition, the average particle size (D10) of the water-insoluble colorant is usually more than 10nm, preferably more than 20nm, and more preferably more than 30nm. The upper limit is preferably less than 100nm. It should be noted that the particle size of the water-insoluble colorant can be measured using laser scattering.

[0074] The content of the dispersant in the total mass of the ink composition according to the present embodiment is usually 0.5 to 6.0% by mass, preferably 0.5 to 4.0% by mass, and more preferably 1.0 to 4.0% by mass.

[0075] [Resin A]

[0076] Resin A is a resin (copolymer) obtained by polymerizing at least C1-C4 alkyl methacrylate and C2-C6 alkyl acrylate. That is, resin A contains at least C1-C4 alkyl methacrylate units and C2-C6 alkyl acrylate units as constituent monomer units. By using such resin A, the VOC component in the ink composition can be reduced, and there is a tendency that the storage stability and redispersibility of the ink composition are further improved. As the type of resin A, for example, block copolymers, random copolymers, graft copolymers, etc. can be cited, preferably random copolymers. Resin A can be in the form of a salt. Resin A can be synthesized by a known method.

[0077] Examples of C1-C4 alkyl methacrylates include those having a linear alkyl moiety such as methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, and n-butyl methacrylate; those having a branched alkyl moiety such as isopropyl methacrylate, isobutyl methacrylate, and tert-butyl methacrylate; and those having a cyclic alkyl moiety such as cyclopropyl methacrylate and cyclobutyl methacrylate. Among these, those having a linear alkyl moiety are preferred, those having a linear alkyl moiety such as C1-C3 alkyl methacrylate are more preferred, and methyl methacrylate is still more preferred.

[0078] Examples of C2-C6 alkyl acrylates include those having a linear alkyl portion such as ethyl acrylate, n-propyl acrylate, n-butyl acrylate, n-pentyl acrylate, and n-hexyl acrylate; those having a branched alkyl portion such as isopropyl acrylate, isobutyl acrylate, isopentyl acrylate, and isohexyl acrylate; and those having a cyclic alkyl portion such as cyclobutyl acrylate, cyclopentyl acrylate, and cyclohexyl acrylate. Among these, those having a linear alkyl portion are preferred, those having a linear alkyl portion are more preferred, and butyl acrylate is further preferred.

[0079] The resin A may be a resin obtained by polymerizing other monomers (1) such as C2-C4 unsaturated alkyl methacrylate, methacrylic acid, sodium styrene sulfonate, etc. in addition to C1-C4 alkyl methacrylate and C2-C6 alkyl acrylate. The other monomers (1) may be used alone or in combination of two or more.

[0080] Examples of the C2-C4 unsaturated alkyl methacrylate include vinyl methacrylate, allyl methacrylate, 3-methyl-3-butynyl methacrylate, etc. Among these, C3 unsaturated alkyl methacrylate is preferred, and allyl methacrylate is more preferred.

[0081] The range of the usage amount of C1-C4 alkyl methacrylate (preferably methyl methacrylate), C2-C6 alkyl acrylate (preferably butyl acrylate) and other monomers (1) is shown in the following Table 1. It is preferred to adjust within the range of Table 1 so that the total amount of the monomer mixture obtained from C1-C4 alkyl methacrylate, C2-C6 alkyl acrylate and other monomers (1) is 100 parts by mass. The numerical values ​​in Table 1 are "parts by mass", and the abbreviations and the like have the following meanings.

[0082] MC1-4: C1-C4 alkyl methacrylate

[0083] AC2-6: Acrylic acid C2-C6 alkyl ester

[0084] [Table 1]

[0085] Range of usage generally Best More preferred Further optimization MC1-4 33.0～57.0 35.0～55.0 37.0～53.0 39.0～51.0 AC2-6 27.0～62.0 30.0～59.4 32.0～56.0 35.4～54.0 Other monomers (1) 0～15.0 5.6～15.0 7.0～15.0 7.0～13.6

[0086] Resin A is preferably a resin obtained by polymerizing all of C2-C4 unsaturated alkyl methacrylate (preferably allyl methacrylate), methacrylic acid, and sodium styrene sulfonate as other monomers (1). In this case, the amount of C2-C4 unsaturated alkyl methacrylate used is preferably 0.5 to 2.0 parts by mass, more preferably 0.7 to 2.0 parts by mass, and further preferably 0.7 to 1.8 parts by mass, relative to 100 parts by mass of the total amount of the monomer mixture. In addition, the amount of methacrylic acid used is preferably 5.0 to 12.0 parts by mass, more preferably 6.0 to 12.0 parts by mass, and further preferably 6.0 to 11.0 parts by mass, relative to 100 parts by mass of the total amount of the monomer mixture. In addition, the amount of sodium styrene sulfonate used is preferably 0.1 to 1.0 parts by mass, more preferably 0.3 to 1.0 parts by mass, and further preferably 0.3 to 0.8 parts by mass, relative to 100 parts by mass of the total amount of the monomer mixture.

[0087] Resin A can be synthesized or obtained as a commercial product. When synthesizing resin A, it is preferred to use a reactive emulsifier together with the above-mentioned monomer mixture. By using a reactive emulsifier, an emulsion of resin A can be obtained. When preparing the ink composition involved in this embodiment, it is preferred to use such an emulsion of resin A.

[0088] Reactive emulsifiers are emulsifiers having free radical polymerizable double bonds in the molecule. The number of free radical polymerizable double bonds is usually 1. As the reactive emulsifier, an anionic reactive emulsifier having an anionic group in the molecule is preferred. Such anionic reactive emulsifiers are sometimes also referred to as "reactive anionic surfactants" and the like. As anionic groups, for example, sulfonic acid groups, sulfonic acid ester groups, sulfate groups, phosphoric acid groups, phosphate groups, nitrate groups, carboxyl groups and their salts can be cited. Among these, sulfonic acid groups, sulfonic acid ester groups, sulfate groups and their salts are preferred, and salts of sulfate groups are more preferred. As salts, ammonium salts, alkali metal salts (such as sodium salts, potassium salts, etc.) and the like can be cited.

[0089] Among the reactive emulsifiers, ethylenically unsaturated monomers having a group selected from a sulfonic acid group, a sulfonic acid ester group, a sulfate ester group, a phosphoric acid group, a phosphoric acid ester group, and salts thereof are preferred.

[0090] Specific examples of the reactive emulsifier include ammonium polyoxyalkylene alkenyl ether sulfate, ammonium ether sulfate, phosphoric acid ester, bis(polyoxyethylene polycyclic phenyl ether) methacrylate sulfate, sodium sulfoethyl methacrylate, alkoxy polyethylene glycol maleate, and salts thereof. Specific examples of the reactive emulsifier include sodium alkyl allyl sulfosuccinate (ELEMINOL JS-20 manufactured by Sanyo Chemical Industries, Ltd.), dipotassium alkenyl succinate (LATEMULASK manufactured by Kao Corporation), polyoxyethylene alkyl propylene phenyl ether sulfate salt (Aqualon HS-10 manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), α-[1-[(allyloxy)methyl]-2-(nonylphenoxy)ethyl]-ω-polyoxyethylene sulfate salt (ADEKA REASOAP SE-10N and other ADEKA REASOAP SE series manufactured by ADEKA Corporation), polyoxyethylene-1-(allyloxymethyl) alkyl ether sulfate ammonium salt (Aqualon KH-1025 and other Aqualon KH series manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), styrene sulfonate (Spinomar HS-10 manufactured by Tosoh Finechem Co., Ltd.)

[0063] Examples of the present invention include ammonium salts of sodium succinate, sodium succinate-1,4-dimethoxy-1,4-dimethoxy-1,4-dimethoxy-1,4-dimethoxy-1,4-dimethoxy-1,4-dimethoxy-1,4-dimethoxy-1,4-dimethoxy-1,4-dimethoxy-1,4-dimethoxy-1,4-dimethoxy-1,4-dimethoxy-1,4-dimethoxy-1,4-dimethoxy-1,4-dimethoxy-1,4-dimethoxy-1,4-dimethoxy-1,4-dimethoxy-1,4-dimethoxy-1,4-dimethoxy-1,4-dimethoxy-1,4-dimethoxy-1,4-dimethoxy-1,4-dimethoxy-1,4-dimethoxy-1,4-dimethoxy-1,4-dimethoxy-1,4-dimethoxy-1,4-dimethoxy-1,4-dimethoxy-1,4-dimethoxy-1,4-dimethoxy-1,4-dimethoxy-1,4-dimethoxy-1,4-dimethoxy-1,4-dimethoxy-1 Among these, preferred is an ammonium salt of [(an ethylene oxide addition polymer of {a reaction product of a C10-C14 branched alkanol and 1-(allyloxy)-2,3-propylene oxide} having {α-[2-(allyloxy)-1-({C10-C14 alkyloxy}methyl)ethyl]-ω-hydroxypoly (n=1 to 100)(ethylene oxide)} as a main component)].

[0091] The amount of the reactive emulsifier used when synthesizing resin A is not particularly limited. As a standard for the amount used, it is usually 0.1 to 10% by mass, preferably 0.3 to 5% by mass, more preferably 0.5 to 3% by mass, and further preferably 1 to 3% by mass relative to the total mass of the above-mentioned monomer mixture. By using the reactive emulsifier within the above-mentioned range, there is a tendency that resin A can be stably synthesized, the average particle size of resin A can be controlled within a preferred range, and the viscosity of the emulsion of resin A can be adjusted within a preferred range.

[0092] The average particle size of resin A is usually 10 to 500 nm, preferably 20 to 200 nm, more preferably 25 to 150 nm, and further preferably 30 to 130 nm. When the average particle size is within the range of 10 to 500 nm, clogging of the inkjet head and reaggregation of resin A tend to be suppressed.

[0093] The glass transition temperature (Tg) of the resin A is usually 10 to 65° C., preferably 20 to 60° C., more preferably 30 to 55° C., and further preferably 40 to 50° C. The acid value of the resin A is usually 20 to 85 mgKOH / g, preferably 30 to 80 mgKOH / g, more preferably 40 to 75 mgKOH / g, and further preferably 50 to 70 mgKOH / g.

[0094] The insolubility of resin A in tetrahydrofuran is usually 60 to 100%, preferably 70 to 80%. By setting the insolubility to this level, the average molecular weight of resin A is controlled and a resin free of unreacted monomers and the like as impurities tends to be obtained.

[0095] In the total mass of the ink composition involved in this embodiment, the lower limit of the content of resin A (value converted as solid content) is usually 0.1 mass %, preferably 0.2 mass %, more preferably 0.3 mass %, and the upper limit is usually 10 mass %, preferably 7 mass %, more preferably 6 mass %, and further preferably 5 mass %.

[0096] [Resin B]

[0097] Resin B is a resin (copolymer) obtained by polymerizing at least a styrene monomer and divinylbenzene. That is, resin B contains at least a styrene monomer unit and a divinylbenzene unit as a constituent monomer unit. By using such a resin B, there is a tendency to maintain the storage stability of the ink composition and further improve the friction resistance of the ink composition. As the type of resin B, for example, block copolymers, random copolymers, graft copolymers, etc. can be cited, preferably random copolymers. Resin B can be in the form of a salt. Resin B can be synthesized by a known method.

[0098] The styrene monomer is a compound in which a substituent containing an ethylenically unsaturated bond is bonded to a monocyclic aromatic ring, and may further have a halogen atom such as a fluorine atom, a chlorine atom, or a bromine atom; an alkyl group such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a tert-butyl group, an octyl group; a nitro group; an amino group; a hydroxyl group; a sulfonic group; a carboxyl group; and the like. The alkyl group serving as a substituent may further be substituted with a halogen atom or the like. Examples of the styrene monomer include styrene, p-fluorostyrene, m-fluorostyrene, 2,3,4,5,6-pentafluorostyrene, p-chlorostyrene, o-chlorostyrene, m-chlorostyrene, p-bromostyrene, o-bromostyrene, m-bromostyrene, α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, 1-ethyl-2-vinylbenzene, 3-(trifluoromethyl)styrene, 4-isopropenyltoluene, 4-tert-butylstyrene, 4-n-octylstyrene, 2,4,6-trimethylstyrene, 4-vinylbiphenyl, 4-vinylbenzoic acid, 4-vinylbenzamide, and o-vinylbenzyl Cyanide, m-vinylbenzyl cyanide, 4-methoxystyrene, 2-vinylphenylacetic acid, 1-(1-ethoxyethoxy)-4-vinylbenzene, 4-tert-butoxystyrene, methyl 4-vinylbenzoate, 4-vinylphenyl acetate, 4-(trifluoromethyl)styrene, 4-(chloromethyl)styrene, 4-fluoro-α-methylstyrene, p-nitrostyrene, p-aminostyrene, m-aminostyrene, trimethyl(4-vinylphenyl)silane, trimethoxy(4-vinylphenyl)silane, diphenyl(4-vinylphenyl)phosphine, 3-vinylphenylboric acid, 4-vinylphenylboric acid, sodium styrenesulfonate, etc. Among these, styrene, α-methylstyrene and sodium styrenesulfonate are preferred, and styrene and sodium styrenesulfonate are more preferred, because they have good reactivity during polymerization and excellent stability of resin particles.

[0099] Examples of divinylbenzene include 1,2-divinylbenzene, 1,3-divinylbenzene, and 1,4-divinylbenzene.

[0100] The resin B may be a resin obtained by polymerizing other monomers (2) such as acrylic acid, methacrylic acid, and n-dodecylmercaptan in addition to the styrene monomer and divinylbenzene. The other monomers (1) may be used alone or in combination of two or more.

[0101] The standard range of the usage amount of the styrene-based monomer, divinylbenzene and other monomers (2) is shown in the following Table 2. It is preferable to adjust it within the range of Table 2 so that the total amount of the monomer mixture obtained from the styrene-based monomer, divinylbenzene and other monomers (2) becomes 100 parts by mass. The numerical values ​​in Table 2 are "parts by mass", and the abbreviations and the like have the following meanings.

[0102] STM: Styrene Monomer

[0103] DVB: divinylbenzene

[0104] [Table 2]

[0105] Range of usage generally Best More preferred Further optimization STM 25.5～56.8 27.6～54.8 29.8～52.0 33.6～49.8 DVB 43.0～67.0 45.0～65.0 47.0～63.0 49.0～61.0 Other monomers (2) 0～6.5 1.1～6.5 1.7～6.5 1.7～5.9

[0106] Resin B is preferably a resin obtained by polymerizing styrene and sodium styrene sulfonate as styrene monomers. In this case, the amount of styrene used is preferably 27.5 to 53.8 parts by mass, more preferably 29.5 to 51.0 parts by mass, and further preferably 33.3 to 49.0 parts by mass, relative to 100 parts by mass of the total amount of the monomer mixture. In addition, the amount of sodium styrene sulfonate used is preferably 0.1 to 1.0 parts by mass, more preferably 0.3 to 1.0 parts by mass, and further preferably 0.3 to 0.8 parts by mass, relative to 100 parts by mass of the total amount of the monomer mixture.

[0107] In addition, resin B is preferably a resin obtained by polymerizing all of acrylic acid, methacrylic acid and n-dodecyl mercaptan as other monomers (2). In this case, the amount of acrylic acid used is preferably 0.5 to 2.5 parts by mass, more preferably 0.7 to 2.5 parts by mass, and further preferably 0.7 to 2.3 parts by mass, relative to 100 parts by mass of the total amount of the monomer mixture. In addition, the amount of methacrylic acid used is preferably 0.5 to 3.0 parts by mass, more preferably 0.7 to 3.0 parts by mass, and further preferably 0.7 to 2.8 parts by mass, relative to 100 parts by mass of the total amount of the monomer mixture. In addition, the amount of n-dodecyl mercaptan used is preferably 0.1 to 1.0 parts by mass, more preferably 0.3 to 1.0 parts by mass, and further preferably 0.3 to 0.8 parts by mass, relative to 100 parts by mass of the total amount of the monomer mixture.

[0108] Resin B can be synthesized or obtained as a commercial product. When synthesizing resin B, it is preferred to use the above-mentioned reactive emulsifier together with the above-mentioned monomer mixture. By using a reactive emulsifier, an emulsion of resin B can be obtained. When preparing the ink composition involved in this embodiment, it is preferred to use such an emulsion of resin B.

[0109] The amount of the reactive emulsifier used when synthesizing resin B is not particularly limited. As a standard for the amount used, it is usually 0.1 to 10% by mass, preferably 0.3 to 5% by mass, more preferably 0.5 to 3% by mass, and further preferably 1 to 3% by mass relative to the total mass of the above-mentioned monomer mixture. By using the reactive emulsifier within the above-mentioned range, there is a tendency that resin B can be stably synthesized, the average particle size of resin B can be controlled within a preferred range, and the viscosity of the emulsion of resin B can be adjusted within a preferred range.

[0110] The average particle size of the resin B is usually 10 to 500 nm, preferably 20 to 300 nm, more preferably 40 to 200 nm, and further preferably 50 to 150 nm. When the average particle size is within this range, clogging of the inkjet head and reaggregation of the resin B tend to be suppressed.

[0111] The glass transition temperature (Tg) of the resin B is usually 70 to 280° C., preferably 100 to 270° C., more preferably 150 to 260° C., and further preferably 200 to 250° C. The acid value of the resin B is usually 3 to 80 mgKOH / g, preferably 5 to 70 mgKOH / g, more preferably 10 to 60 mgKOH / g, and further preferably 15 to 50 mgKOH / g.

[0112] The insolubility of resin B in tetrahydrofuran is usually 60 to 100%, preferably 70 to 80%. By setting the insolubility to this level, the average molecular weight of resin B is controlled and a resin free of unreacted monomers and the like as impurities tends to be obtained.

[0113] In the total mass of the ink composition involved in this embodiment, the lower limit of the content of resin B (value converted as solid content) is usually 0.1 mass %, preferably 0.2 mass %, more preferably 0.3 mass %, and the upper limit is usually 10 mass %, preferably 7 mass %, more preferably 6 mass %, and further preferably 5 mass %.

[0114] Resin A and resin B can be used in any combination ratio. By changing the combination ratio, the washability, scratch resistance, color development and glossiness of the printed material are improved, and the VOC reduction during ink design can also be expected. When the content of resin A (value converted by solid content) in the ink composition involved in this embodiment is set to A, the content of resin B (value converted by solid content) is set to B, and the combination ratio is expressed as a value obtained by "A / B", A / B is preferably 0.1 to 10, more preferably 0.2 to 5, further preferably 0.2 to 4, particularly preferably 0.25 to 2.34, and extremely preferably 0.25 to 1.0.

[0115] [water]

[0116] As water, water with a small content of impurities (metal ions etc.) such as ion-exchanged water and distilled water is preferred.

[0117] The content of water in the total mass of the ink composition according to the present embodiment is usually 30 to 80% by mass, preferably 35 to 75% by mass, and more preferably 40 to 70% by mass.

[0118] [Water-soluble organic solvent]

[0119] The ink composition involved in this embodiment preferably further contains a water-soluble organic solvent. Examples of the water-soluble organic solvent include C1-C6 alkanols such as methanol, ethanol, propanol, isopropanol, butanol, isobutanol, sec-butanol, and tert-butanol; carboxylic acid amides such as N,N-dimethylformamide and N,N-dimethylacetamide; lactams such as 2-pyrrolidone, N-methyl-2-pyrrolidone, and N-methylpyrrolidone-2-one; cyclic ureas such as 1,3-dimethylimidazolidin-2-one and 1,3-dimethylhexahydropyrimidin-2-one; acetone, 2-methyl-2-hydroxybenzoic acid, and the like. 1-C6 alkylene units such as ethylene glycol, diethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butylene glycol, 1,4-butylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, polyethylene glycol (preferably having a molecular weight of 400, 800, 1540 or more), polypropylene glycol, thiodiglycol, dithiodiglycol, etc. Mono-, oligo- or poly-alkylene glycols and thioglycols; C3-C9 polyols (triols) such as glycerol, diglycerol, hexane-1,2,6-triol and trimethylolpropane; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoallyl ether, ethylene glycol monoisopropyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monobutyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, Glycol ethers such as glycol monomethyl ether (preferably glycol ethers selected from the group consisting of C3-C10 mono-, di- or triethylene glycol ethers, and C4-C13 mono-, di- or tripropylene glycol ethers); C5-C9 alkane diols such as 1,2-pentanediol, 1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 2-methyl-2,4-pentanediol, 2-ethyl-1,3-hexanediol, and 2,4-diethyl-1,5-pentanediol; γ-butyrolactone; dimethyl sulfoxide; etc. Among these, it is preferred to use at least one water-soluble organic solvent selected from the group consisting of glycol ethers and C5-C9 alkane diols.

[0120] The content of the water-soluble organic solvent in the total mass of the ink composition according to the present embodiment is usually 0 to 60 mass %, preferably 1 to 60 mass %, more preferably 2 to 50 mass %, further preferably 3 to 45 mass %, particularly preferably 5 to 40 mass %.

[0121] [Other ingredients]

[0122] The ink composition according to the present embodiment may contain an ink modifier in addition to the above-mentioned components. Examples of the ink modifier include surfactants (excluding components corresponding to reactive emulsifiers), preservatives and mildew inhibitors, pH adjusters, and defoamers.

[0123] The total content of the ink preparation agents in the total mass of the ink composition according to the present embodiment is usually 0 to 30% by mass, preferably 0.1 to 20% by mass, and more preferably 0.5 to 10% by mass.

[0124] As the surfactant, anionic, cationic, nonionic, amphoteric, silicone-based and fluorine-based surfactants can be cited. Among these, silicone-based and fluorine-based surfactants are preferred, and silicone-based surfactants are more preferred from the viewpoint of safety for organisms and the environment.

[0125] Examples of the anionic surfactant include alkyl sulfocarboxylates, α-olefin sulfonates, polyoxyethylene alkyl ether acetates, polyoxyethylene alkyl ether sulfates, N-acylamino acids or salts thereof, N-acylmethyl taurates, alkyl sulfate polyoxyalkyl ether sulfates, alkyl sulfate polyoxyethylene alkyl ether phosphates, rosin soaps, castor oil sulfate ester salts, lauryl sulfate ester salts, alkylphenol type phosphate esters, alkyl type phosphate esters, alkylaryl sulfonates, diethyl sulfosuccinate, diethylhexyl sulfosuccinate, and dioctyl sulfosuccinate.

[0126] Examples of the cationic surfactant include 2-vinylpyridine derivatives and poly-4-vinylpyridine derivatives.

[0127] Examples of the nonionic surfactant include ethers such as polyoxyethylene nonylphenyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene dodecylphenyl ether, polyoxyethylene oleyl ether, polyoxyethylene lauryl ether, polyoxyethylene alkyl ether, and polyoxyethylene distyrenated phenyl ether (e.g., Emulgen A-60, A-90, and A-500 manufactured by Kao Corporation); esters such as polyoxyethylene oleate, polyoxyethylene distearate, sorbitan laurate, sorbitan monostearate, sorbitan monooleate, sorbitan sesquioleate, polyoxyethylene monooleate, and polyoxyethylene stearate; acetylene glycol (alcohol) such as 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 3,6-dimethyl-4-octyne-3,6-diol, and 3,5-dimethyl-1-hexyn-3-ol; and polyglycol ethers. Examples of commercially available products thereof include SURFYNOL 104, 104PG50, 82, 420, 440, 465, 485, and OLFINE STG manufactured by Nissin Chemical Industry Co., Ltd. and EMULGE NA-60, A-90, and A-500 manufactured by Kao Corporation.

[0128] Examples of the amphoteric surfactant include lauryl dimethylaminoacetic acid betaine, 2-alkyl-N-carboxymethyl-N-hydroxyethylimidazolinium betaine, coconut oil fatty acid amide propyl dimethylaminoacetic acid betaine, polyoctylpolyaminoethylglycine, and imidazoline derivatives.

[0129] Examples of the silicone surfactant include polyether-modified siloxane and polyether-modified polydimethylsiloxane. Examples thereof include Dynol 960 and 980 manufactured by Air Products; Silface SAG001, SAG002, SAG003, SAG005, SAG503A, SAG008, SAG009, and SAG010 manufactured by Nissin Chemical Industry Co., Ltd.; BYK-345, 347, 348, 349, 3455, LP-X23288, LP-X23289, and LP-X23347 manufactured by BYK Additives & Instruments; and TEGO Twin 4000, TEGO Wet KL 245, 250, 260, 265, 270, and 280 manufactured by Evonic Tego Chemie.

[0130] Examples of the fluorine-based surfactant include perfluoroalkylsulfonic acid compounds, perfluoroalkylcarboxylic acid compounds, perfluoroalkylphosphate compounds, perfluoroalkylethylene oxide adducts, and polyoxyalkylene ether polymer compounds having a perfluoroalkyl ether group in a side chain.

[0131] Examples of the antiseptic and antifungal agent include organic sulfur compounds, organic nitrogen sulfur compounds, organic halogen compounds, halogenated aryl sulfone compounds, iodopropargyl compounds, halogenated alkylthio compounds, nitrile compounds, pyridine compounds, 8-hydroxyquinoline compounds, benzothiazole compounds, isothiazolin compounds, dithiol compounds, pyridine oxide compounds, nitropropane compounds, organic tin compounds, phenol compounds, quaternary ammonium salt compounds, triazines compounds, thiazine compounds, anilide compounds, adamantane compounds, dithiocarbamate compounds, indanone bromide compounds, benzyl bromoacetate compounds, inorganic salt compounds, sodium dehydroacetate, sodium benzoate, sodium pyrithione-1-oxide, ethyl p-hydroxybenzoate, 1,2-benzisothiazolin-3-one, and salts thereof. Examples of commercially available antiseptic and antifungal agents include PROXEL GXL (S) and XL-2 (S) manufactured by Lonza.

[0132] As the pH adjuster, any substance can be used as long as it is a compound that can adjust the pH of the prepared ink composition to 5 to 11 without adversely affecting the pH thereof. Specific examples thereof include alkanolamines such as diethanolamine, triethanolamine, and N-methyldiethanolamine; alkali metal hydroxides such as lithium hydroxide, sodium hydroxide, and potassium hydroxide; ammonium hydroxide (ammonia water); alkali metal carbonates such as lithium carbonate, sodium carbonate, sodium bicarbonate, and potassium carbonate; alkali metal salts of organic acids such as sodium silicate and potassium acetate; inorganic bases such as disodium phosphate; and the like.

[0133] Examples of defoamers include silicone-based, silica mineral oil-based, olefin-based, and acetylene-based compounds. Examples of commercially available defoamers include SURFYNOL DF37, DF58, DF110D, DF220, and MD-20, and OLFINE SK-14, all manufactured by Shin-Etsu Chemical Co., Ltd.

[0134] When a defoamer is used, the content of the defoamer is usually 0.01 to 5% by mass, preferably 0.03 to 3% by mass, and more preferably 0.05 to 1% by mass. When the content of the defoamer is 0.01% by mass or more, the effect as a defoamer tends to be obtained, and when it is 5% by mass or less, the dispersion stability tends to be good.

[0135] [Physical properties of ink composition, etc.]

[0136] When the ink composition according to the present embodiment is used as an ink for inkjet recording, it is preferred to use an ink composition having a low content of inorganic impurities such as chloride (e.g., sodium chloride) and sulfate (e.g., sodium sulfate) of metal cations in the ink composition. The standard content of the inorganic impurities is about 1% by mass or less relative to the total mass of the colorant. The lower limit may be below the detection limit of the analytical device, i.e., 0% by mass.

[0137] Inorganic impurities are often mixed in the colorant. Therefore, the colorant can be purified by removing the inorganic impurities from the colorant as needed. Examples of purification methods include: a method of suspending the solid colorant in a mixed solvent of C1-C4 alcohol such as methanol and water; a method of exchanging and adsorbing the inorganic impurities using an ion exchange resin after preparing the ink; and the like.

[0138] The pH of the ink composition involved in this embodiment at 25°C is usually 7 to 11, preferably 8 to 10. The surface tension of the ink composition involved in this embodiment at 25°C is usually 10 to 50 mN / m, preferably 20 to 40 mN / m. The viscosity of the ink composition involved in this embodiment at 25°C is usually 2 to 30 mPa·s, preferably 3 to 20 mPa·s. The pH, surface tension and viscosity of the ink composition involved in this embodiment can be appropriately adjusted by selecting the type and amount of the pH adjuster, surfactant, water-soluble organic solvent, etc.

[0139] The ink composition according to the present embodiment has excellent storage stability, ejection stability, re-dissolution and re-dispersibility, and can also reduce VOC. In addition, by printing using the ink composition according to the present embodiment, a printed material with a good balance of light resistance, ozone resistance, moisture resistance, chroma, color development, glossiness, abrasion resistance, bronze gloss, silver ink properties, and bleeding can be obtained.

[0140] The ink composition according to the present embodiment can be used in various recording applications. For example, the ink composition according to the present embodiment is suitable for writing instruments, various printings, information recording, printing and dyeing, and is particularly preferably used in inkjet recording.

[0141] <Inkjet recording method, inkjet printer, and recording medium>

[0142] The inkjet recording method according to the present embodiment is to use an inkjet printer to eject droplets of the ink composition according to a recording signal and cause the droplets to adhere to a recording medium, thereby performing recording. When performing inkjet recording, a container filled with the ink composition can be loaded at a predetermined position of the inkjet printer, thereby performing recording as described above.

[0143] In the inkjet recording method of this embodiment, the above-mentioned ink composition can be used alone or in combination with other ink compositions. For example, in order to obtain a full-color recorded image, the above-mentioned ink composition can be used in combination with other ink compositions having a different hue from the ink composition.

[0144] For industrial inkjet printers, in order to achieve high printing speed, it is also preferred to implement single pass printing with a linear head type inkjet printer. According to the above-mentioned ink composition, even under such printing conditions, a recorded image with good color development and excellent friction resistance can be obtained.

[0145] As the inkjet method, a known method can be used. Specific examples of the inkjet method include, for example, a charge control method, a drop-on-demand inkjet (pressure pulse) method, an acoustic inkjet method, a thermal inkjet method, and the like. In addition, the following methods are also included: a method of improving the image quality by ejecting an ink composition with a small content of a colorant in the ink composition in a small volume in large quantities; a method of improving the image quality by using a plurality of ink compositions having substantially the same hue but different concentrations of colorants in the ink composition; a method of improving the fixability of the colorant by using a colorless and transparent ink composition; and the like.

[0146] The recording medium refers to a material to which the ink composition can adhere. Examples of the recording medium include paper, film, fiber or cloth (cellulose, nylon, wool, etc.), leather, and a substrate for a color filter.

[0147] Recording media can be roughly divided into recording media having an ink receiving layer and recording media not having an ink receiving layer.

[0148] Recording media with an ink-receiving layer are generally referred to as special inkjet paper, special inkjet film, glossy paper, etc. Representative commercial products include professional photo paper, super photo paper, glossy Glod, and matte photo paper manufactured by Canon Co., Ltd.; photo paper CRISPIA (high gloss), photo paper (gloss), and matte photo paper manufactured by Seiko Epson Corp.; high-grade photo paper (gloss) manufactured by Hewlett-Packard Co., Ltd. of Japan; and color photo retouching Pro manufactured by FUJI FILM Co., Ltd.; etc.

[0149] Examples of recording media without an ink receiving layer include various papers such as coated paper and art paper used in gravure printing, offset printing, etc.; cast-coated paper used in label printing; etc. The above-mentioned ink composition can be preferably used for recording media without an ink receiving layer.

[0150] When using a recording medium without an ink receiving layer, it is also preferable to perform a surface modification treatment on the recording medium for the purpose of improving the fixability of the colorant, etc. Examples of the surface modification treatment include corona discharge treatment, plasma treatment, and flame treatment.

[0151] Regarding all the above matters, a combination of preferred items is more preferred, and a combination of more preferred items is further preferred. The same applies to a combination of a preferred item and a more preferred item, a combination of a more preferred item and a further preferred item, and the like.

[0152] Example

[0153] Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to the examples.

[0154] In the examples, unless otherwise specified, "part" means part by mass, and "%" means mass %. For various synthesis, preparation and other operations in the examples, unless otherwise specified, they were all carried out under stirring. In addition, when the content of the solid component in the liquid was measured, MS-70 manufactured by A&D Co., Ltd. was used to obtain it by the dry weight method.

[0155] The "water" used in the examples is ion-exchanged water.

[0156] In addition, the reactive emulsifier used in the examples is an ammonium salt of a sulfated product of [(ethylene oxide addition polymer of {the reaction product of C10-C14 branched alkanol and 1-(allyloxy)-2,3-propylene oxide}, with {α-[2-(allyloxy)-1-({C10-C14 alkyloxy}methyl)ethyl]-ω-hydroxypoly (n=1-100)(ethylene oxide)} as the main component)].

[0157] [Preparation Example 1: Preparation of Resin A]

[0158] A reflux condenser, a thermometer and a dropping funnel were installed in a glass reaction container (3 L capacity) equipped with a stirrer, and ion exchange water (152 parts), sodium polyoxyethylene alkyl ether sulfate (1.4 parts) and potassium persulfate (0.3 parts) were added. After replacing the air inside with nitrogen, the internal temperature was adjusted to 80°C while stirring, and the raw material liquid (emulsion) was continuously added dropwise over 3 hours. The raw material liquid was prepared by mixing and stirring ion exchange water (62 parts), sodium polyoxyethylene alkyl ether sulfate (0.99 parts), reactive emulsifier (1 part), butyl acrylate (41 parts), methyl methacrylate (47 parts), methacrylic acid (10 parts), sodium styrene sulfonate (0.5 parts) and allyl methacrylate (1.5 parts) in another container and emulsifying them. During the dropwise addition, the reaction was carried out at 80°C while introducing nitrogen. After the dropwise addition was completed, it was further stirred at 85°C for 2 hours and then cooled to 40°C. After cooling, triethanolamine (1.1 parts) was added to obtain an emulsion of resin A (modified acrylic resin). The obtained resin A had an acid value of 65 mgKOH / g and a Tg of 47°C.

[0159] [Preparation Example 2: Preparation of Resin B]

[0160] A reflux condenser, a thermometer and a dropping funnel were installed in a glass reaction container (3 L capacity) equipped with a stirrer, and ion exchange water (289 parts), sodium lauryl sulfate (0.7 parts) and sodium persulfate (0.1 parts) were added. After replacing the air inside with nitrogen, the internal temperature was adjusted to 80°C while stirring, and the raw material liquid (emulsion) was continuously added dropwise over 3 hours. The raw material liquid was prepared by mixing and stirring ion exchange water (84 parts), sodium lauryl sulfate (6.6 parts) and a reactive emulsifier (1 part), and styrene (37.06 parts), methacrylic acid (1.8 parts), acrylic acid (1.15 parts), divinylbenzene (59.04 parts), n-dodecyl mercaptan (0.57 parts) and sodium styrene sulfonate (0.38 parts) in another container and emulsifying them. During the dropwise addition, the reaction was carried out at 80°C while nitrogen was introduced. After the dropwise addition was completed, the mixture was further stirred at 85°C for 2 hours and then cooled to 40°C. After cooling, polyoxyethylene lauryl ether (4 parts) and triethanolamine (1.5 parts) were added to obtain an emulsion of resin B (styrene resin cross-linked with divinylbenzene). The obtained resin B had an acid value of 21 mgKOH / g and a Tg of 225°C.

[0161] [Preparation Example 3: Preparation of a dispersion of a colorant]

[0162] An additional test was conducted on Synthesis Example 3 of International Publication No. 2013 / 115071, thereby obtaining a block copolymer (block copolymer A). 2-Butanone (8.2 parts) and block copolymer A (10.62 parts) were added to the liquid obtained by dissolving sodium hydroxide (0.36 parts) in ion exchange water (64.4 parts), and stirred for 1 hour to prepare a uniform solution. CI Pigment Blue 15:4 (manufactured by BASF, Heliogen Blue D 7115F) (16 parts) was added to the liquid, and a dispersion treatment was performed in a sand mill at 1500 rpm for 15 hours to obtain a liquid. After water (100 parts) was added dropwise to the obtained liquid, the liquid was filtered to obtain a filtrate. A portion of 2-butanone and water were distilled off from the obtained filtrate under reduced pressure using an evaporator to obtain a colorant dispersion having a colorant content of 12.4%. The average particle size (D50) of the colorant is 138 nm, the average particle size (D90) is 230 nm, and the average particle size (D10) is 81 nm.

[0163] [Examples 1 to 5: Preparation of ink composition]

[0164] The components listed in Table 3 below were mixed to obtain 100 parts of liquids in total, and the obtained liquids were filtered using a membrane filter having a pore size of 3 μm to obtain ink compositions of Examples 1 to 5 for evaluation tests.

[0165] [Comparative Examples 1-2: Preparation of ink composition]

[0166] The components listed in Table 3 below were mixed to obtain 100 parts of liquids in total, and the obtained liquids were filtered using a membrane filter having a pore size of 3 μm to obtain ink compositions of Comparative Examples 1 and 2 for evaluation tests.

[0167] [Preparation Example 4: Preparation of cleaning solution]

[0168] A cleaning liquid for evaluation test was obtained in the same manner as in Examples 1 to 5 except that the components described in the following Table 3 were used.

[0169] The abbreviations and the like in Table 3 below have the following meanings. The numerical values ​​in the columns of each component in Table 3 represent the usage amount (parts) of the component, and "-" means that the component is not used. In addition, the number of parts in the columns of Resin A and Resin B in Table 3 is the value converted by solid content of each resin.

[0170] PG: Propylene glycol (manufactured by Junsei Chemical Co., Ltd.)

[0171] 2Py: 2-pyrrolidone (manufactured by Junsei Chemical Co., Ltd.)

[0172] 12HD: 1,2-Hexanediol (manufactured by Kanto Chemical Co., Ltd.)

[0173] TEA: triethanolamine (manufactured by Kanto Chemical Co., Ltd.)

[0174] TEX: TEXANOL (manufactured by Eastman Chemical Company)

[0175] BYK-349: Silicone surfactant (BYK, BYK-349)

[0176] GXL(S): PROXEL GXL(S) (manufactured by Lonza)

[0177] Resin A: The emulsion of Resin A obtained in Preparation Example 1

[0178] Resin B: Emulsion of Resin B obtained in Preparation Example 2

[0179] [Table 3]

[0180]

[0181] [Inkjet recording]

[0182] Using a printer manufactured by KYOCERA Corporation equipped with an inkjet head KJ4B-YH (600 dpi×600 dpi), inkjet recording was performed on OK Topcoat+ of coated paper manufactured by Prince Paper Co., Ltd. using the ink composition obtained in each embodiment and comparative example under the conditions of a droplet size of 12 pl and a speed of 25 m / min. The inkjet recording was performed in a manner to form a three-dimensional image with 100% duty, and a recorded image recorded by the ink composition of each embodiment or comparative example was obtained. Using it as a test piece, a color development test and a scratch test were performed. It should be noted that in the color measurement of each test piece, a colorimeter manufactured by X-rite, trade name eXact, was used. The color measurement conditions are: concentration reference ISO state T, field angle of 2°, and light source D50.

[0183] [Color development test]

[0184] Using each test piece obtained as described above, colorimetry was performed on the Dc value (OD value). The results are shown in the following Table 4. The larger the obtained Dc value, the better the color development property.

[0185] [Scratch test]

[0186] The scratch resistance of each test piece was evaluated using a pencil & spring load scratch hardness tester (according to JIS K5600-5-4, manufactured by COTEC Co., Ltd.). That is, a test was performed by pressing the inkjet recorded portion at an angle of 45° and applying a load of 750 g to the test piece using a tester with two wheels, and the evaluation was performed according to the following three-level evaluation criteria. The results are shown in Table 4 below.

[0187] -Evaluation Criteria-

[0188] A: There is almost no visible scratch on the recorded image.

[0189] B: A small amount of scratches can be confirmed in the recorded image.

[0190] C: The scratch on the recorded image is very large.

[0191] [Cleaning test]

[0192] 20 μL of the ink composition of each example and comparative example was dripped onto a glass plate (Flat Schale 70 manufactured by Tokyo Glass Instrument Co., Ltd.), and allowed to stand in a thermostatic bath at 60° C. for 1 hour to dry, thereby obtaining a solid material in which the ink composition had been cured. 10 mL of the cleaning solution obtained in Preparation Example 4 was dripped onto the obtained solid material, and it was visually evaluated whether the solid material could be dissolved and removed. The evaluation criteria were set to the following 4 levels. The results are shown in Table 4 below.

[0193] -Evaluation Criteria-

[0194] A: No solid residue was observed, and a uniform liquid was formed.

[0195] B: Slightly no solid matter remained, but a substantially uniform liquid was formed.

[0196] C: Solid matter obviously remained, and no uniform liquid was observed.

[0197] [Glossiness (20°, 60°)]

[0198] The glossiness (20°, 60°) of each test piece was measured using a handheld gloss meter (manufactured by Nippon Denshoku Industries Co., Ltd.). The results are shown in the following Table 4. Generally, as the color development property is high, the glossiness value increases.

[0199] [Content rate of VOC components]

[0200] The content of VOC components in the ink compositions of the respective Examples and Comparative Examples was evaluated. The evaluation criteria were set to the following four levels. The results are shown in Table 4 below.

[0201] -Evaluation Criteria-

[0202] A: The content of VOC components in the ink composition is 23% by mass or less.

[0203] B: The content of the VOC component in the ink composition is greater than 23% by mass and less than or equal to 25% by mass.

[0204] C: The content of VOC components in the ink composition is greater than 25% by mass.

[0205] [Table 4]

[0206]

[0207] From the results in Table 4, it can be confirmed that the ink compositions of each example are excellent in color development and scratch resistance. In addition, it can be confirmed that, even when the ink compositions of each example are dried and solid matter is generated, the solid matter can be sufficiently washed. On the other hand, the ink compositions of each comparative example are poor in color development and cannot simultaneously achieve scratch resistance and washing properties.

Claims

1. An ink composition comprising a water-insoluble colorant, a dispersant, a resin A, a resin B and water, The resin A is a resin obtained by polymerizing at least a C1-C4 alkyl methacrylate and a C2-C6 alkyl acrylate. The resin B is a resin obtained by polymerizing at least a styrene-based monomer and divinylbenzene.

2. The ink composition according to claim 1, wherein Each of the resin A and the resin B is a resin obtained by polymerizing a reactive emulsifier having a radical polymerizable double bond in the molecule.

3. The ink composition according to claim 2, wherein The reactive emulsifier is a reactive emulsifier having an anionic group in the molecule.

4. The ink composition according to claim 3, wherein The anionic group is a salt of a sulfate ester group. 5 . The ink composition according to claim 1 , further comprising a water-soluble organic solvent.

6. An inkjet recording method, wherein: Recording is performed by discharging droplets of the ink composition according to any one of claims 1 to 4 in response to a recording signal using an inkjet printer and causing the droplets to adhere to a recording medium.

7. The inkjet recording method according to claim 6, wherein: The recording medium is a recording medium having an ink receiving layer.

8. The inkjet recording method according to claim 6, wherein The recording medium is a recording medium having no ink receiving layer.

9. The inkjet recording method according to claim 6, wherein: The inkjet printer is a linear nozzle type inkjet printer. 10 . A recording medium having the ink composition according to claim 1 adhered thereto.

11. The recording medium according to claim 10, wherein The recording medium is a recording medium selected from a recording medium having an ink receiving layer and a recording medium not having an ink receiving layer. 12 . An inkjet printer comprising a container filled with the ink composition according to claim 1 .

13. The inkjet printer according to claim 12, wherein: The inkjet printer is a linear nozzle type inkjet printer.

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