Ink set and recording method

Abstract

To provide a recording method that can form a high quality image even at a high recording rate.SOLUTION: An ink set includes a treatment liquid containing a coagulant and an ink composition. The ink composition is a water-based ink containing: a pigment dispersed by a pigment dispersant or a self-dispersible pigment; a water-dispersible resin; and a maleic acid-based resin, which is a water-soluble resin.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to an ink set and a recording method.

Background Art

[0002] Since the inkjet method can form a high-quality image on a recording medium, various technical developments have been conventionally made. For example, not only the development of a recording apparatus using the inkjet method but also the development of an ink composition and an ink set used in the apparatus have been actively carried out.

[0003] For example, it has also been studied to use a reaction solution for the purpose of controlling the cohesiveness of the dispersed components in the ink composition. For example, in Patent Document 1, an attempt has been made to obtain a high-quality image by allowing a reaction solution containing a flocculant to act on an ink composition containing a pigment and wax as a dispersion.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By including the reaction solution in the ink set, for example, an action of quickly fixing the ink on the recording medium by the reaction solution and an action of suppressing the aggregation of ink dots can be expected. Further, when the components contained in the ink composition are in a dispersed state, the reaction solution can also be expected to improve the image quality obtained by aggregating the dispersed components.

[0006] Typical dispersion components in an ink composition include, for example, pigments and resin particles, but the cohesiveness of these dispersion components often differs from each other. For example, resin particles have different cohesiveness depending on their type, and are often relatively less cohesive than other dispersion components. Therefore, they may be less affected by the action of a flocculant, resulting in insufficient flocculation or a lack of flocculation speed. As a result, flocculation unevenness may occur in the image, or the rub resistance of the image may decrease.

Means for Solving the Problems

[0007] One aspect of the ink set according to the present invention is an ink set including a treatment liquid containing a flocculant and an ink composition, wherein the ink composition is an aqueous ink containing a pigment dispersed by a pigment dispersant or a self-dispersing pigment, a water-dispersible resin, and a maleic acid-based resin which is a water-soluble resin.

[0008] One aspect of the recording method according to the present invention is using the above-described ink set, an ink adhesion step of adhering the ink composition to a recording medium, and a treatment liquid adhesion step of adhering the treatment liquid to the recording medium.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Mode for Carrying Out the Invention

[0010] Embodiments of the present invention will be described below. The embodiments described below illustrate examples of the present invention. The present invention is not limited to the following embodiments, and also includes various modified forms implemented without changing the gist of the present invention. Note that not all of the configurations described below are essential configurations of the present invention.

[0011] In this specification, “(meth)acryl” represents acrylic or methacrylic, and “(meth)acrylate” represents acrylate or methacrylate.

[0012] 1. Ink set The ink set according to this embodiment includes a treatment liquid containing a flocculant and an ink composition. Such an ink composition is an aqueous ink containing a pigment dispersed with a pigment dispersant or a self-dispersing pigment, a water-dispersible resin, and a maleic acid-based resin which is a water-soluble resin.

[0013] An ink set refers to an ink composition and a treatment liquid used for recording as a set. The ink composition and the treatment liquid included in the ink set may be respectively accommodated in separate liquid containers, or may be accommodated in an integral liquid container.

[0014] An ink set includes at least one (one type) of an ink composition and at least one (one type) of a treatment liquid. One or both of the ink composition and the treatment liquid may be provided in two or more.

[0015] 1.1. Ink composition The ink composition is an aqueous ink containing a pigment dispersed with a pigment dispersant or a self-dispersing pigment, a water-dispersible resin, and a maleic acid-based resin which is a water-soluble resin.

[0016] 1.1.1. Pigment The ink composition contains a pigment dispersed with a pigment dispersant or a self-dispersing pigment. As the pigment, carbon black, inorganic pigments including titanium white, organic pigments, etc. can be used.

[0017] As the inorganic pigment, carbon blacks (C.I. Pigment Black 7) such as furnace black, lamp black, acetylene black, channel black, etc., iron oxide, titanium oxide, zinc oxide, silica, etc. can be used.

[0018] Examples of carbon black include No. 2300, 900, MCF88, No. 20B, No. 33, No. 40, No. 45, No. 52, MA7, MA8, MA100, No2200B, etc. manufactured by Mitsubishi Chemical Corporation. Examples can also include Color Black FW1, FW2, FW2V, FW18, FW200, S150, S160, S170, Printex 35, U, V, 140U, Special Black 6, 5, 4A, 4, 250, etc. manufactured by Degussa. Examples can further include Conductex SC, Raven 1255, 5750, 5250, 5000, 3500, 1255, 700, etc. manufactured by Columbian Carbon. Examples can also include Regal 400R, 330R, 660R, Mogul L, Monarch 700, 800, 880, 900, 1000, 1100, 1300, 1400, Elftex 12, etc. manufactured by Cabot.

[0019] Examples of organic pigments include quinacridone pigments, quinacridonequinone pigments, dioxazine pigments, phthalocyanine pigments, anthrapyrimidine pigments, ansanthrone pigments, indanthrone pigments, flavanthrone pigments, perylene pigments, diketopyrrolopyrrole pigments, perinone pigments, quinophthalone pigments, anthraquinone pigments, thioindigo pigments, benzimidazolone pigments, isoindolinone pigments, azomethine pigments or azo pigments, etc. Specific examples of the organic pigments used in the ink composition include the following.

[0020] Specific examples of the organic pigments used in the ink composition include the following.

[0021] Examples of cyan pigments include C.I. Pigment Blue 1, 2, 3, 15:3, 15:4, 15:34, 16, 22, 60, etc.; C.I. Vat Blue 4, 60, etc. Preferably, examples thereof include one or more mixtures selected from the group consisting of C.I. Pigment Blue 15:3, 15:4, and 60.

[0022] Examples of magenta pigments include C.I. Pigment Red 5, 7, 12, 48 (Ca), 48 (Mn), 57 (Ca), 57:1, 112, 122, 123, 168, 184, 202, C.I. Pigment Violet 19, etc. Preferably, examples thereof include one or more mixtures selected from the group consisting of C.I. Pigment Red 122, 202, and 209, and C.I. Pigment Violet 19.

[0023] Examples of yellow pigments include C.I. Pigment Yellow 1, 2, 3, 12, 13, 14C, 16, 17, 73, 74, 75, 83, 93, 95, 97, 98, 119, 110, 114, 128, 129, 138, 150, 151, 154, 155, 180, 185, etc. Preferably, examples thereof include one or more mixtures selected from the group consisting of C.I. Pigment Yellow 74, 109, 110, 128, and 138.

[0024] Examples of orange pigments include C.I. Pigment Orange 36 or 43, or a mixture thereof. Examples of pigments used in green inks include C.I. Pigment Green 7 or 36, or a mixture thereof.

[0025] The above-exemplified pigments are examples of suitable pigments and are not limited thereto. One or more of these pigments may be used.

[0026] The pigments may be dispersed and used with a pigment dispersant. Alternatively, the pigments may be dispersed and used as self-dispersing pigments by oxidizing or sulfonating the pigment surface with ozone, hypochlorous acid, fuming sulfuric acid, etc.

[0027] The pigment dispersant has the function of dispersing pigments in the ink composition. The pigment dispersant may be water-soluble, but those without complete water solubility are preferred. It is considered that part or all of the pigment dispersant binds or adsorbs to the pigment, enhancing the hydrophilicity of the pigment surface and thereby dispersing the pigment. The type of the pigment dispersant is not particularly limited.

[0028] The pigment dispersant is a polymer compound. Examples thereof include acrylic resins such as poly(meth)acrylic acid, (meth)acrylic acid-acrylonitrile copolymer, (meth)acrylic acid-(meth)acrylate copolymer, vinyl acetate-(meth)acrylate copolymer, vinyl acetate-(meth)acrylic acid copolymer, vinyl naphthalene-(meth)acrylic acid copolymer, styrene-(meth)acrylic acid copolymer, styrene-(meth)acrylic acid copolymer, styrene-(meth)acrylic acid-(meth)acrylate copolymer, styrene-α-methylstyrene-(meth)acrylic acid copolymer, styrene-α-methylstyrene-(meth)acrylic acid-(meth)acrylate copolymer, and salts thereof. In this specification, a polymer having a skeleton derived from (meth)acrylic acid and not having a skeleton derived from maleic acid or a similar compound is referred to as an acrylic resin.

[0029] In addition, examples of the pigment dispersant include maleic acid resins such as styrene-maleic acid copolymer, styrene-maleic anhydride copolymer, vinyl naphthalene-maleic acid copolymer, vinyl acetate-maleic acid ester copolymer, and salts thereof; urethane resins and salts thereof regardless of the presence or absence of a crosslinked structure; polyvinyl alcohols; resins such as vinyl acetate-crotonic acid copolymer and salts thereof. Although these polymers are maleic acid resins, they have low water solubility and are substances for obtaining the dispersibility of pigments by adsorbing to the pigments, so they are different from the maleic acid resins described later.

[0030] In addition to the polymers of the acrylic monomers (acrylic monomers) as described above, the acrylic resin may also be a copolymer of an acrylic monomer and another monomer. For example, an acrylic vinyl resin obtained as a copolymer with a vinyl monomer as another monomer is also referred to as an acrylic resin. Also, for example, among the above styrene resins, those that are copolymers of a styrene monomer and an acrylic monomer are also included in the acrylic resins. Furthermore, when referring to an acrylic resin, its salts and esterified products are also included. Further, in this specification, a copolymer using an acrylic monomer and maleic acid or its derivative as monomers is classified as a maleic acid resin.

[0031] Examples of commercially available pigment dispersants include X-200, X-1, X-205, X-220, X-228 (manufactured by Starlight PMC Co., Ltd.), Nopcosperse (registered trademark) 6100, 6110 (manufactured by San Nopco Ltd.), Joncryl 67, 586, 611, 678, 680, 682, 819 (manufactured by BASF), DISPERBYK-190 (manufactured by BYK Chemie Japan Co., Ltd.), N-EA137, N-EA157, N-EA167, N-EA177, N-EA197D, N-EA207D, E-EN10 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), and the like.

[0032] Examples of commercially available acrylic pigment dispersants include BYK-187, BYK-190, BYK-191, BYK-194N, BYK-199 (manufactured by BYK Chemie GmbH), Aron A-210, A6114, AS-1100, AS-1800, A-30SL, A-7250, CL-2 (manufactured by Toagosei Co., Ltd.), and the like.

[0033] Examples of commercially available urethane pigment dispersants include BYK-182, BYK-183, BYK-184, BYK-185 (manufactured by BYK Chemie GmbH), TEGO Disperse710 (manufactured by Evonic Tego Chemi), Borchi (registered trademark) Gen1350 (manufactured by OMG Borschers), and the like.

[0034] The pigment dispersant may be used alone or in combination of two or more. The total content of the pigment dispersant is 0.1% by mass or more and 30% by mass or less, preferably 0.5% by mass or more and 25% by mass or less, more preferably 1% by mass or more and 20% by mass or less, still more preferably 1.5% by mass or more and 15% by mass or less, based on 100% by mass of the ink. When the content of the pigment dispersant is 0.1% by mass or more, the dispersion stability of the pigment can be ensured. Also, if the content of the pigment dispersant is 30% by mass or less, the viscosity of the ink composition can be kept low.

[0035] Furthermore, it is more preferable that the weight average molecular weight of the pigment dispersant is 500 or more. By using such a pigment dispersant, there is less odor and the dispersion stability of the pigment can be further improved.

[0036] The Tg of the pigment dispersant is preferably 40°C or more, more preferably 70°C or more, still more preferably 90°C or more. On the other hand, it is preferably 120°C or less, more preferably 110°C or less, still more preferably 100°C or less.

[0037] When dispersing the pigment with the pigment dispersant, the ratio of the pigment to the pigment dispersant is preferably 10:1 to 1:10, more preferably 4:1 to 1:3.

[0038] Also, the volume average particle diameter (D50) of the pigment is such that the volume average particle (D50) measured by the dynamic light scattering method is 20 nm or more and 300 nm or less, more preferably the volume average particle diameter (D50) is 30 nm or more and 200 nm or less, still more preferably the volume average particle diameter (D50) is 40 nm or more and 100 nm or less.

[0039] The content of the pigment can be adjusted as appropriate, but is preferably 0.10% by mass or more and 20.0% by mass or less, more preferably 0.20% by mass or more and 15.0% by mass or less, still more preferably 1.0% by mass or more and 10.0% by mass or less. Further, 2.0 to 5.0% by mass is preferable.

[0040] In the ink set of the present embodiment, when the ink composition contains a pigment dispersed by a pigment dispersant, the pigment dispersant is preferably made of an acrylic resin. Thereby, the dispersibility of the pigment in the ink composition can be made better.

[0041] 1.1.2. Water-dispersible resin The ink composition contains a water-dispersible resin. The water-dispersible resin functions as a so-called fixing resin that improves the adhesion of the components of the ink composition adhered to the recording medium, for example. Examples of such water-dispersible resins include urethane resins, acrylic resins (including styrene-acrylic resins), fluorene resins, olefin resins, rosin-modified resins, terpene resins, ester resins, amide resins, epoxy resins, vinyl chloride resins, vinyl chloride-vinyl acetate copolymers, ethylene-vinyl acetate resins, and the like. These water-dispersible resins may be in the form of particles, resin particles, and are often handled in the form of an emulsion. They may also be in the form of a powder. In addition, the water-dispersible resin can be used alone or in combination of two or more.

[0042] The urethane resin is a general term for resins having a urethane bond. In the urethane resin, in addition to the urethane bond, a polyether type urethane resin containing an ether bond in the main chain, a polyester type urethane resin containing an ester bond in the main chain, a polycarbonate type urethane resin containing a carbonate bond in the main chain, etc. can be used. As the water-dispersible resin of the urethane resin, commercially available products may be used. For example, commercially available products such as Superflex 460, 460s, 840, E-4000 (trade name, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), Resamin D-1060, D-2020, D-4080, D-4200, D-6300, D-6455 (trade name, manufactured by Dainichi Seiko Kogyo Co., Ltd.), Takelac WS-6021, W-512-A-6 (trade name, manufactured by Mitsui Chemicals Polyurethane Co., Ltd.), Sun Cure 2710 (trade name, manufactured by Lubrizol), Permaline UA-150 (trade name, manufactured by Sanyo Chemical Industries, Ltd.) may be used.

[0043] An acrylic resin is a general term for polymers obtained by polymerizing at least one acrylic monomer such as (meth)acrylic acid and (meth)acrylic acid ester. Examples include resins obtained from acrylic monomers and copolymers of acrylic monomers and other monomers. For example, acrylic-vinyl resins, which are copolymers of acrylic monomers and vinyl monomers, can be mentioned. Further examples include copolymers with vinyl monomers such as styrene.

[0044] As acrylic monomers, acrylamide, acrylonitrile, etc. can also be used. As commercially available products of water-dispersible resins made from acrylic resins, for example, FK-854 (trade name, manufactured by Central Science Industry Co., Ltd.), Mobinyl 952B, 718A (trade names, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), Nipol LX852, LX874 (trade names, manufactured by Zeon Corporation) etc. may be used.

[0045] Among them, styrene-acrylic resins are copolymers obtained from styrene monomers and acrylic monomers, and examples include styrene-acrylic acid copolymers, styrene-methacrylic acid copolymers, styrene-methacrylic acid-acrylic acid ester copolymers, styrene-α-methylstyrene-acrylic acid copolymers, styrene-α-methylstyrene-acrylic acid-acrylic acid ester copolymers, etc. As water-dispersible resins of styrene-acrylic resins, commercially available products may be used. For example, Joncryl 62J, 7100, 390, 711, 511, 7001, 632, 741, 450, 840, 74J, HRC-1645J, 734, 852, 7600, 775, 537J, 1535, PDX-7630A, 352J, 352D, PDX-7145, 538J, 7640, 7641, 631, 790, 780, 7610 (trade names, manufactured by BASF), Mobinyl 966A, 975N (trade names, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), Vinibran 2586 (manufactured by Nisshin Chemical Industry Co., Ltd.) etc. may be used.

[0046] Olefin resins have structures derived from olefins such as ethylene, propylene, and butylene, and known ones can be appropriately selected and used. As the water-dispersible resin of the olefin resin, commercially available products can be used, and for example, Arrow Base CB-1200, CD-1200 (trade name, manufactured by Unitika Ltd.) etc. may be used.

[0047] Other examples of commercially available emulsions of water-dispersible resins include Microgel E-1002, E-5002 (trade names of products manufactured by Nippon Paint Co., Ltd., styrene-acrylic resin emulsions), Boncoat 4001 (trade name of a product manufactured by DIC Corporation, acrylic resin emulsion), Boncoat 5454 (trade name of a product manufactured by DIC Corporation, styrene-acrylic resin emulsion), Polyzol AM-710, AM-920, AM-2300, AP-4735, AT-860, PSASE-4210E (acrylic resin emulsion), Polyzol AP-7020 (styrene-acrylic resin emulsion), Polyzol SH-502 (vinyl acetate resin emulsion), Polyzol AD-13, AD-2, AD-10, AD-96, AD-17, AD-70 (ethylene-vinyl acetate resin emulsion), Polyzol PSASE-6010 (ethylene-vinyl acetate resin emulsion) (trade name of a product manufactured by Showa Denko K.K.), Polyzol SAE1014 (trade name, styrene-acrylic resin emulsion, manufactured by Nippon Zeon Co., Ltd.), Cybinol SK-200 (trade name, acrylic resin emulsion, manufactured by Cyden Chemical Co., Ltd.), AE-120A (trade name of a product manufactured by JSR Corporation, acrylic resin emulsion), AE373D (trade name of a product manufactured by E-Tech Co., Ltd., carboxy-modified styrene-acrylic resin emulsion), Seikadine 1900W (trade name of a product manufactured by Dainichi Seika Kogyo Co., Ltd., ethylene-vinyl acetate resin emulsion), Vinibran 2682 (acrylic resin emulsion), Vinibran 2886 (vinyl acetate-acrylic resin emulsion), Vinibran 5202 (acrylic acetate resin emulsion) (trade names of products manufactured by Nisshin Chemical Industry Co., Ltd.), Elitel KA-5071S, KT-8803, KT-9204, KT-8701, KT-8904, KT-0507 (trade names of products manufactured by Unitika Ltd., polyester resin emulsion), Hi-Tech SN-2002 (trade name of a product manufactured by Toho Chemical Co., Ltd., polyester resin emulsion), Takelac W-6020, W-635, W-6061, W-605, W-635, W-6021 (trade names of products manufactured by Mitsui Chemicals Polyurethane Co., Ltd., urethane resin emulsion), Superflex 870, 800, 150, 420, 460, 470, 610, 700 (trade names of products manufactured by Daiichi Kogyo Seiyaku Co., Ltd., urethane resin emulsion), Permalin UA-150 (manufactured by Sanyo Chemical Industries, Ltd., urethane resin emulsion),Sun Cure 2710 (manufactured by Nippon Lubrizol Corporation, urethane resin emulsion), NeoRez R-9660, R-9637, R-940 (manufactured by Kusumoto Chemical Co., Ltd., urethane resin emulsion), Adeka Bon Titer HUX-380, 290K (manufactured by ADEKA Corporation, urethane resin emulsion), Mobinyl 966A, Mobinyl 7320 (manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), Joncryl 7100, 390, 711, 511, 7001, 632, 741, 450, 840, 74J, HRC-1645J, 734, 852, 7600, 775, 537J, 1535, PDX-7630A, 352J, 352D, PDX-7145, 538J, 7640, 7641, 631, 790, 780, 7610 (above, manufactured by BASF), NK Binder R-5HN (manufactured by Shin-Nakamura Chemical Co., Ltd.), Hydran WLS-210 (non-crosslinked polyurethane: manufactured by DIC Corporation), Joncryl 7610 (manufactured by BASF), etc. can be mentioned.

[0048] When the ink composition contains a water-dispersible resin, the content is preferably 10% by mass or less, more preferably 7% by mass or less, and even more preferably 5% by mass or less as a solid content based on the total mass of the ink composition. In this way, an image with sufficiently good rubbing fastness can be recorded.

[0049] When the ink composition contains a water-dispersible resin as a resin, the glass transition temperature (Tg) of the water-dispersible resin is preferably 40°C or higher, more preferably 50°C or higher, and even more preferably 55°C or higher. On the other hand, it is preferably 100°C or lower, more preferably 90°C or lower, and even more preferably 80°C or lower. When the glass transition temperature point is within the above range, it is preferable because an image with better rubbing fastness can be recorded. The glass transition temperature can be confirmed by differential scanning calorimetry (DSC).

[0050] In addition, when the ink composition contains a particulate water-dispersible resin as a resin, the volume average particle diameter of the particles of the water-dispersible resin is preferably 200 nm or less, more preferably 150 nm or less, and even more preferably 100 nm or less. When the volume average particle diameter is within the above range, it is preferable because recording can be performed with more excellent ejection stability. The volume average particle diameter of the particles of the water-dispersible resin can be confirmed in the same manner as the volume average particle diameter of the pigment.

[0051] Depending on the skeleton of the resin and the nature of the functional groups that make up its particles, the water-dispersible resin may exhibit aggregability due to the action of a flocculant such as calcium propionate described later. In the ink set of the present embodiment, the water-dispersible resin may not have aggregability when mixed with an aqueous calcium propionate solution. When the water-dispersible resin does not have aggregability, the abrasion resistance of the image tends to be good, and even if the water-dispersible resin does not have aggregability, due to the aggregability of the maleic acid-based resin described later, an image with sufficient image quality can be obtained by the ink set of the present embodiment. From such a viewpoint, there is a preferable ratio between the content of the water-dispersible resin and the content of the maleic acid-based resin as described later.

[0052] Having aggregability means that when evaluated by the aggregability evaluation method in the examples described later, it is determined that the reactivity is good or there is reactivity. Further, not having aggregability means that when evaluated by the same evaluation method, it is determined that there is no reactivity.

[0053] The water-dispersible resin is preferably any one of an acrylic resin, a urethane resin, and a polyolefin resin. Further, the water-dispersible resin is preferably contained in a total amount of 0.5% by mass or more and 20% by mass or less, more preferably 1% by mass or more and 15% by mass or less, and even more preferably 2% by mass or more and 12% by mass or less based on the total amount of the ink composition. When the content of the water-dispersible resin in the ink composition is within this range, the abrasion resistance of the obtained image can be further improved by the ink set.

[0054] Furthermore, the water-dispersible resin is preferably an acrylic resin, but when a silicone-acrylic resin and a urethane resin are used in combination, the abrasion resistance of the image tends to be further improved. However, when doing so, the clogging recovery property may decrease, so the urethane resin is preferably 1% by mass or less based on the entire ink composition.

[0055] 1.1.3. Maleic acid resin The ink composition contains a maleic acid resin which is a water-soluble resin. The water-soluble resin is a resin having a solubility of more than 10 g in 100 g of water at 20°C when the solubility is determined by the following method.

[0056] The solubility is determined as follows. A predetermined amount of resin dried at 105°C for 2 hours to reach a constant weight is dissolved in 100 g of water at 20°C and stirred for 30 minutes. If there is no residue after stirring, it is judged to be dissolved. In this way, when a predetermined amount of resin is mixed with 100 g of water at 20°C, the largest predetermined amount judged to be dissolved is defined as the solubility.

[0057] The maleic acid resin is a high molecular compound having a structure derived from maleic acids. Examples of maleic acids include compounds having a structure in which one carboxyl group is bonded to each of adjacent carbon atoms bonded by the carbon-carbon double bond of ethylene, and compounds which are derivatives thereof.

[0058] Specific examples of maleic acids include maleic acid, maleic anhydride, fumaric acid, citraconic acid, citraconic anhydride, mesaconic acid, etc. The carboxyl groups bonded to the adjacent carbon atoms may be those obtained by dehydration cyclization or esterification. Those in which the carboxyl group forms a salt are also included in the carboxyl group.

[0059] Examples of the above derivatives include those in which the carboxyl group is derived as described above, and those in which the ethylene skeleton further has a substituent.

[0060] Among maleic acids, maleic acid and those derived from the carboxyl group of maleic acid are preferred.

[0061] The maleic acid-based resin may be one in which the carboxyl group derived from maleic acids is dehydrated and cyclized or esterified. Those in which the carboxyl group forms a salt are also included in the carboxyl group.

[0062] The polymer compound having a structure derived from maleic acids can be a polymer compound obtained by polymerizing or copolymerizing at least using maleic acids.

[0063] The maleic acid-based resin may be a polymer of maleic acids or a copolymer of maleic acids and other monomers. Examples of other monomers in this case include vinyl monomers such as styrene, vinyl naphthalene, and vinyl acetate, and acrylic monomers such as (meth)acrylic acid and esters of (meth)acrylic acid.

[0064] The maleic acid-based resin has a structure derived from maleic acids and has a carboxyl group or a structure derived from a carboxyl group on adjacent carbon atoms. Here, for example, when a polymer of acrylic acid is polymerized by a generally known method, since it polymerizes in a so-called head-to-tail manner, it is statistically rare for carboxyl groups to be arranged on adjacent carbons. Therefore, compared with the case of polymerizing maleic acids, it is rare for carboxyl groups to be arranged adjacent to each other in the carbon chain of the main chain in the polymer of acrylic acids. Thereby, it is possible to confirm whether the origin of adjacent carboxyl groups is derived from maleic acids by, for example, NMR (nuclear magnetic resonance method).

[0065] The carboxyl groups of the maleic acid-based resin may be esterified. For example, they may be esterified with a compound having a hydroxyl group. The two carboxyl groups having a structure derived from maleic acids may not be esterified, or one of them may be esterified, or both of them may be esterified.

[0066] Also, when the carboxyl groups having a structure derived from maleic acids are not esterified, they may exist as carboxylic acids in the aqueous ink composition, or may be partially or completely neutralized with ammonia, alkanolamine or alkylamine.

[0067] Since the maleic acid-based resin contains many structures derived from the carboxyl groups of maleic acids, it has water solubility. Therefore, in the aqueous ink composition, the molecular chains of the maleic acid-based resin have a spread. As a result, when the ink composition and the treatment liquid are mixed, the probability that the maleic acid-based resin meets the flocculant is increased. Therefore, the maleic acid-based resin has good aggregability, and thereby the image quality of the image obtained using an inkjet can be improved.

[0068] When one of the two carboxyl groups having a structure derived from maleic acids of the maleic acid-based resin is esterified, the water resistance of the obtained image tends to be improved. Also, when the two carboxyl groups having a structure derived from maleic acids are not esterified, the water resistance of the obtained image tends to decrease. Depending on the degree of esterification, the balance between hydrophilicity and hydrophobicity of the maleic acid-based resin can be adjusted, whereby the storage stability of the ink composition can be made better and the water resistance of the obtained image can be further improved. For example, styrene maleic anhydride half ester copolymer salt is preferable in terms of the balance between hydrophilicity and hydrophobicity. This is presumably because the esterified carboxyl group has high hydrophobicity and promotes insolubilization and solid-liquid separation during the reaction.

[0069] When the maleic acid-based resin contains a structure derived from maleic anhydride, it is considered that in water, the anhydride has been converted to a carboxyl group by hydration.

[0070] The maleic acid-based resin is a water-soluble resin, and it is preferably present as a solution dissolved in water, which is a solvent component of the ink, without adsorbing to pigments or the like in the ink composition. Thereby, excellent aggregability is exhibited.

[0071] The maleic acid-based resin described in this section is contained in the ink separately from the pigment dispersant when the ink contains a pigment dispersed by the pigment dispersant.

[0072] The maleic acid-based resin exhibits aggregability due to the action of a flocculant such as calcium propionate, which will be described later, depending on the resin skeleton, the number of functional groups, and the properties of the particles constituting the resin. In the ink set of this embodiment, the maleic acid-based resin has aggregability when mixed with an aqueous solution of calcium propionate. Due to the aggregability of the maleic acid-based resin, an image with sufficient image quality can be obtained by the ink set of this embodiment. From such a viewpoint, there is a preferable ratio between the content of the water-dispersible resin and the content of the maleic acid-based resin, as will be described later.

[0073] The maleic acid-based resin preferably has acidic groups such as carboxyl groups, sulfonic acid groups, and phosphoric acid groups. That is, even when the carboxyl group derived from maleic acids exists in the form of an acid or a salt, or when all of the carboxyl groups derived from maleic acids are esterified, it is preferable that the skeleton and the ester group have acidic groups such as carboxyl groups, sulfonic acid groups, and phosphoric acid groups in the form of an acid or a salt. Further, the acidic group may be partially or completely neutralized with ammonia, alkanolamine, or alkylamine.

[0074] According to such maleic acid resins, the cohesiveness is better, so that the image quality of the obtained image can be further improved. Further, according to this ink set, the dissolution of the maleic acid resin becomes more stable, so that the storage stability of the ink composition can be made better.

[0075] The weight average molecular weight of the maleic acid resin is preferably 2,000 or more and 100,000 or less, more preferably 5 000 or more and 60,000 or less, and even more preferably 10,000 or more and 50,000 or less. When the weight average molecular weight is within this range, the suppression of aggregation unevenness of the obtained image and the improvement of abrasion resistance can be further improved. The ejection stability from the inkjet head is also good.

[0076] Examples of commercially available maleic acid resins include SN Dispersant 5027, 5029 (manufactured by Sanshin Chemical Industry Co., Ltd.), Sans Pearl PS-8 (manufactured by Sanyo Chemical Industries, Ltd.), Maria Rim HKM-50A, 150A, AKM-0531, SC-0505K, Polyster OMA (manufactured by NOF Corporation), Demol P, EP, ST, Boys 520, 521 (manufactured by Kao Corporation), Polyti A550 (manufactured by Lion Corporation), Alaster 703S, Polymeron 1318, 351T, 385, 372, 375CB, 482, 482S, 1329 (manufactured by Arakawa Chemical Industries, Ltd.), Xiran 1440H, 2625H, 1000H, 2000H, 3000H (manufactured by Polyscope), Isoban-104 (manufactured by Kuraray Co., Ltd.), Floren G-700AMP, G-700DMEA (manufactured by Kyoeisha Chemical Co., Ltd.), and the like.

[0077] The content of the maleic acid resin in the ink composition is preferably 0.05% by mass or more and 3.0% by mass or less, more preferably 0.05% by mass or more and 2.5% by mass or less, still more preferably 0.1% by mass or more and 1.5% by mass or less, even more preferably 0.2% by mass or more and 1.0% by mass or less, and particularly preferably 0.3% by mass or more and 0.8% by mass or less, based on the total amount of the ink composition. If the content is within this range, the effect of the flocculant of the treatment liquid can be sufficiently and significantly obtained by the inkjet, and a high-quality image can be formed.

[0078] 1.1.4. Ratio of components, total content, etc. In the ink composition of the inkjet of the present embodiment, a better blending ratio can be found between the above-mentioned water-dispersible resin and the maleic acid resin. That is, the ratio (B / A) of the content (B) of the maleic acid resin to the content (A) of the water-dispersible resin in the ink composition is preferably 0.19 or less, more preferably 0.17 or less, still more preferably 0.15 or less, and even more preferably 0.13 or less. Also, it is preferably 0.01 or more, more preferably 0.03 or more, and still more preferably 0.05 or more.

[0079] If the ratio (B / A) is within this range, the rub resistance of the formed image can be further improved.

[0080] Also, in the inkjet, the total amount of the water-dispersible resin and the maleic acid resin contained in the ink composition is preferably 0.05% by mass or more and 5% by mass or less, more preferably 0.1% by mass or more and 3% by mass or less, still more preferably 0.2% by mass or more and 2% by mass or less, and even more preferably 0.5% by mass or more and 1.5% by mass or less, based on the total amount of the ink composition.

[0081] By setting the total amount of the water-dispersible resin and the maleic acid resin within this range, the effect of suppressing the aggregation unevenness of the image and the effect of enhancing the rub resistance of the image can be obtained more significantly.

[0082] 1.1.5. Water-soluble low molecular weight organic compound The ink composition may contain a water-soluble low-molecular-weight organic compound. In this specification, the water-soluble low-molecular-weight organic compound refers to an organic compound having a solubility of more than 10 g in 100 g of water at 20°C and a molecular weight of 500 or less. The molecular weight is preferably 400 or less, more preferably 300 or less.

[0083] In particular, it may contain a water-soluble low-molecular-weight organic compound having a standard boiling point of 150°C or higher and 250°C or lower. Yes.

[0084] The solubility is determined as follows. First, in an environment of 20°C, a predetermined amount of the compound is mixed with 100 g of water and stirred for 30 minutes. After stirring, for a compound that is liquid at room temperature, if it is not phase-separated or has a sea-island structure, it is judged to be dissolved. For a compound that is solid at room temperature, if there is no residue, it is judged to be dissolved.

[0085] In this way, when a predetermined amount of the organic compound is mixed with 100 g of water at 20°C and it is judged to be dissolved, the largest predetermined amount is taken as the solubility.

[0086] The water-soluble low-molecular-weight organic compound is preferably a compound having a melting point of 80°C or lower. When the melting point is within the above range, the clogging recovery property and the discharge stability tend to be excellent.

[0087] Examples of the water-soluble low-molecular-weight organic compound include polyols. It is preferable to contain polyols having a standard boiling point of 150°C or higher and 250°C or lower.

[0088] If polyols having a standard boiling point of 150°C or higher and 250°C or lower are contained, the moisture retention property of the ink composition can be further enhanced, and when the ink set is used in an inkjet recording apparatus, the clogging recovery property of the nozzles of the recording head can be further improved.

[0089] Polyols are organic compounds having two or more hydroxyl groups, and examples thereof include alkane derivatives having two or more hydroxyl groups and those having two or more hydroxyl groups in an alkylene ether having 4 or less carbon atoms.

[0090] Examples of polyols having a standard boiling point of 150°C or higher and 250°C or lower include 1,2-ethanediol (ethylene glycol) [197°C], 1,2-propanediol (propylene glycol) [188°C], 1,2-butanediol [194°C], 1,2-pentanediol [210°C], 1,2-hexanediol [224°C], 1,2-heptanediol [227°C], 1,3-propanediol [210°C], 1,3-butanediol [230°C], 1,4-butanediol [230°C], 2,3-butanediol [177°C], 1,5-pentanediol [242°C], 1,6-hexanediol [250°C], 2-ethyl-2-methyl-1,3-propanediol [226°C], 2-methyl-1,3-propanediol [214°C], 2,2-dimethyl-1,3-propanediol [210°C], 3-methyl-1,3-butanediol [203°C], 3-methyl-1,5-pentanediol [250°C], 2-methylpentane-2,4-diol [197°C], diethylene glycol [245°C], dipropylene glycol [232°C], etc. The numerical values in parentheses represent the standard boiling point. These alkyl polyols may be used alone or in combination of two or more.

[0091] Examples of glycol ethers that are polyols include the above-mentioned ones or others such as ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, etc.

[0092] Polyols can mainly function as penetration solvents and / or humectant solvents. Polyhydric alcohols tend to have strong properties as humectant solvents. Also, some alkanediols have strong properties as penetration solvents and / or strong properties as humectant solvents.

[0093] The ink composition may use one of the above polyols alone or two or more of them.

[0094] The ink composition may contain any one of amides, sulfur-containing solvents, and cyclic ethers as the water-soluble low-molecular-weight organic compound. In particular, it may contain any one of amides, sulfur-containing solvents, and cyclic ethers having a standard boiling point of 150°C or higher and 300°C or lower. If it contains any one of amides, sulfur-containing solvents, and cyclic ethers having a standard boiling point of 150°C or higher and 300°C or lower, the water-soluble low-molecular-weight organic compound easily functions as a dissolution aid for the water-dispersible resin, so that the particles of the water-dispersible resin are liable to swell and / or soften. Thereby, the flatness of the surface of the formed image is further improved, and the abrasion resistance of the image can be further enhanced.

[0095] Examples of the amides include cyclic amides. Examples of the cyclic amides include lactams. Examples of the lactams include, for example, 2-pyrrolidone [245°C], 2-piperidone [256°C], ε-caprolactam [267°C], N-methyl-ε-caprolactam [248°C], N-cyclohexyl-2-pyrrolidone [290°C], 1-methyl-2-pyrrolidone [202°C], 1-ethyl-2-pyrrolidone [218°C], 1-propyl-2-pyrrolidone [227°C], 1-butyl-2-pyrrolidone [241°C], 5-methyl-2-pyrrolidone [248°C], succinimide [287°C], ω-heptalactam, and the like. These are preferable in terms of promoting film formation of the water-dispersible resin, and 2-pyrrolidone is particularly more preferable (the numerical values in parentheses represent the standard boiling point).

[0096] Examples of the amides also include acyclic amides. The acyclic amides are amides having no cyclic structure in the molecule.

[0097] Examples of the acyclic amide include, for example, N,N-dialkylamide. Examples of the N,N-dialkylamide include, for example, N,N-dialkylalkylamide, N,N-dialkylalkoxyalkylamide, N,N-dialkylacetoacetamide, and the like. Examples of the N,N-dialkylalkoxyalkylamide include compounds represented by the following general formula (1).

[0098] R 1 -O-CH 2 CH 2 -(C=O)-NR 2 R 3 ···(1)

[0099] In the above formula (1), R 1 represents an alkyl group having 1 to 4 carbon atoms, and R 2 and R 3 each independently represent a methyl group or an ethyl group. The "alkyl group having 1 to 4 carbon atoms" can be a linear or branched alkyl group, and examples thereof can include a methyl group, an ethyl group, an n-propyl group, an iso-propyl group, an n-butyl group, a sec-butyl group, an iso-butyl group, and a tert-butyl group. The compounds represented by the above formula (1) may be used alone or in combination of two or more.

[0100] Also, in the above formula (1), R 1 is more preferably a methyl group having 1 carbon atom. In the above formula (1), the normal boiling point of the compound in which R 1 is a methyl group is lower than that of the compound in which R 1 is an alkyl group having 2 to 4 carbon atoms. Therefore, when a compound in which R 1 is a methyl group is used in the above formula (1), the surface dryness of the adhesion region may be further improved.

[0101] As functions of the amides, for example, improving the surface drying property and the fixing property of an ink composition adhered onto a low-absorbency recording medium can be mentioned. In particular, the compound represented by the above formula (1) is excellent in the action of moderately softening and dissolving a vinyl chloride-based resin. Therefore, the compound represented by the above formula (1) can soften and dissolve the recording surface of a recording medium containing a vinyl chloride-based resin, and allow the ink composition to penetrate into the recording medium. By thus allowing the ink composition to penetrate into the recording medium, the components of the ink composition are firmly fixed, and the surface of the ink composition becomes more easily dried. Therefore, the obtained image tends to be excellent in surface drying property and fixing property. Thus, the obtained image tends to be excellent in surface drying property and fixing property.

[0102] Specific examples of acyclic amides among amides with a standard boiling point of 150 °C or higher and 300 °C or lower include N,N-dimethylacetoacetamide [220 °C], N,N-diethylacetoacetamide, N-methylacetoacetamide [279 °C], N,N-dimethylformamide [153 °C], N,N-diethylformamide, N,N-dimethylacetamide [165 °C], N,N-diethylacetamide, N,N-dimethylpropionamide, N,N-dimethylisobutyramide [175 °C], 3-methoxy-N,N-dimethylpropanamide [215 °C], 3-n-butoxy-N,N-dimethylpropionamide [252 °C], 3-methoxy-N,N-diethylpropionamide, 3-methoxy-N,N-methylethylpropionamide, 3-ethoxy-N,N-dimethylpropionamide, 3-ethoxy-N,N-diethylpropionamide, 3-ethoxy-N,N-methylethylpropionamide, 3-n-butoxy-N,N-diethylpropionamide, 3-n-butoxy-N,N-methylethylpropionamide, 3-n-propoxy-N,N-dimethylpropionamide, 3-n-propoxy-N,N-diethylpropionamide, 3-n-propoxy-N,N-methylethylpropionamide, 3-iso-propoxy-N,N-dimethylpropionamide, 3-iso-propoxy-N,N-diethylpropionamide, 3-iso-propoxy-N,N-methylethylpropionamide, 3-tert-butoxy-N,N-dimethylpropionamide, 3-tert-butoxy-N,N-diethylpropionamide, 3-tert-butoxy-N,N-methylethylpropionamide, and the like.

[0103] Examples of sulfur-containing solvents with a standard boiling point of 150 °C or higher and 300 °C or lower include dimethyl sulfoxide [189 °C], tetramethylene sulfoxide [235 °C], diethyl sulfoxide, methyl phenyl sulfoxide, 3-methyl sulfolane [276 °C], sulfolane [285 °C], ethyl isopropyl sulfone [251 °C], ethyl methyl sulfone, dimethyl sulfone [248 °C], and the like (the numerical values in parentheses represent the standard boiling point).

[0104] In addition, examples of cyclic ethers having a standard boiling point of 150°C or higher and 300°C or lower include 3-methyl-3-oxetanemethanol, 3-ethyl-3-oxetanemethanol [220°C], 2-hydroxymethyloxetane, isosorbide dimethyl ether [240°C], tetrahydrofurfuryl alcohol [176°C], solketal [192°C], glycerol formal [192°C], 1,4-dioxane-2,3-diol [259°C], dihydrolevoglucosenone [227°C], and the like (the numerical values in parentheses represent the standard boiling point).

[0105] When a water-soluble low-molecular-weight organic compound is used in the ink composition, its content is preferably 5% by mass or more and 40% by mass or less, more preferably 10% by mass or more and 30% by mass or less, and even more preferably 15% by mass or more and 25% by mass or less, in total based on the total amount of the ink composition. With a content within this range, the flatness of the surface of the formed image can be further improved, and the abrasion resistance of the image can be further enhanced.

[0106] 1.1.6. Other Components The ink composition may contain the following components in addition to the above components.

[0107] (1) Water The ink composition may contain water. The ink composition is an aqueous ink. Aqueous means a composition containing water as one of the main solvent components. Water may be contained as the main solvent component and is a component that evaporates by drying. Water is preferably pure water or ultrapure water such as ion-exchanged water, ultrafiltered water, reverse osmosis permeated water , distilled water, etc., with ionic impurities removed as much as possible. Also, using water sterilized by ultraviolet irradiation or hydrogen peroxide addition is suitable because it can suppress the generation of mold and bacteria when the treatment liquid or ink composition is stored for a long time. The content of water is preferably 40% by mass or more, more preferably 45% by mass or more, even more preferably 50% by mass or more and 98% by mass or less, and still more preferably 55% by mass or more and 95% by mass or less, based on the total amount of the ink composition.

[0108] (2) Organic Solvent The ink composition may contain an organic solvent. The organic solvent is a low-molecular organic compound that is liquid at normal temperature. Among the above-mentioned water-soluble low-molecular organic compounds, those that are liquid at normal temperature can also be organic solvents.

[0109] The organic solvent may be a water-soluble low-molecular organic compound or other than a water-soluble low-molecular organic compound. The organic solvent is preferably a water-soluble organic solvent. Functions of the organic solvent include improving the wettability of the ink composition with respect to the recording medium and enhancing the moisture retention of the ink composition. Examples of the organic solvent include esters, alkylene glycol ethers, cyclic esters, etc. in addition to those mentioned above. Note that the ink composition may contain polyols such as trimethylolpropane and glycerin having a standard boiling point of 280 °C or higher as needed.

[0110] The organic solvent contained in the ink composition preferably has a standard boiling point of 280.0 °C or lower, more preferably 160.0 °C or higher and 270.0 °C or lower, still more preferably 180.0 °C or higher and 260.0 °C or lower, and even more preferably 200.0 °C or higher and 250.0 °C or lower. Selecting such an organic solvent is preferable because properties such as rub resistance and ejection stability are likely to be better.

[0111] Examples of the esters include ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, Glycol monoacetates such as propylene glycol monomethyl ether acetate, dipropylene glycol monomethyl ether acetate, methoxybutyl acetate, etc., and glycol diacetates such as ethylene glycol diacetate, diethylene glycol diacetate, propylene glycol diacetate, dipropylene glycol diacetate, ethylene glycol acetate propionate, ethylene glycol acetate butyrate, diethylene glycol acetate butyrate, diethylene glycol acetate propionate, diethylene glycol acetate butyrate, propylene glycol acetate propionate, propylene glycol acetate butyrate, dipropylene glycol acetate butyrate, dipropylene glycol acetate propionate, etc. are included.

[0112] As the alkylene glycol ethers, a monoether or diether of alkylene glycol may be used, and an alkyl ether is preferred. Specific examples include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl 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, tetraethylene glycol monomethyl ether, tetraethylene glycol monoethyl ether, tetraethylene glycol monobutyl ether, propylene glycol monomethyl ether Alkylene glycol monoalkyl ethers such as tellurium, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monobutyl ether, and tripropylene glycol monobutyl ether, and alkylene glycol dialkyl ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, diethylene glycol methyl ethyl ether, diethylene glycol methyl butyl ether, triethylene glycol dimethyl ether, triethylene glycol diethyl ether, triethylene glycol dibutyl ether, triethylene glycol methyl butyl ether, tetraethylene glycol dimethyl ether, tetraethylene glycol diethyl ether, tetraethylene glycol dibutyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, dipropylene glycol dimethyl ether, dipropylene glycol diethyl ether, and tripropylene glycol dimethyl ether are mentioned.

[0113] Also, the above alkylene glycol ethers are more preferably diethers than monoethers in that they tend to dissolve or swell the water-dispersible resin in the treatment liquid or ink composition, and the abrasion resistance of the formed image tends to be good. On the other hand, monoethers are more preferably used for better improving the wettability of the ink composition.

[0114] Examples of cyclic esters (lactones) include β-propiolactone, γ-butyrolactone, δ-valerolactone, ε-caprolactone, β-butyrolactone, β-valerolactone, γ-valerolactone, β-hexanolactone, γ-hexanolactone, δ-hexanolactone, β-heptanolactone, γ-heptanolactone, δ-heptanolactone, ε-heptanolactone, γ-octanolactone, δ-octanolactone, ε-octanolactone, δ-nonalactone, ε-nonalactone, ε-decanolactone and other cyclic esters (lactones), and compounds in which the hydrogen of the methylene group adjacent to the carbonyl group is substituted by an alkyl group having 1 to 4 carbon atoms can be mentioned.

[0115] The total content of the organic solvents with respect to the total mass of the ink composition is preferably 40% by mass or less. On the other hand, it is preferably 5% by mass or more. Furthermore, it is preferably 5% by mass or more and 40% by mass or less, more preferably 10% by mass or more and 35% by mass or less, and still more preferably 15% by mass or more and 30% by mass or less. In particular, when the total content of the organic solvents with respect to the total mass of the ink composition is 30% by mass or less, it is preferable in that the discharge stability of the ink composition can be improved while the wet rubbing resistance of the image can be improved.

[0116] (3) Dye A dye may be used in the ink composition. Examples of dyes include acid dyes, direct dyes, reactive dyes, and basic dyes as water-soluble types, and disperse dyes, oil-soluble dyes, sublimation dyes, etc. as water-dispersible types.

[0117] (4) Surfactant The ink composition may contain a surfactant. The surfactant has a function of reducing the surface tension of the ink composition and improving the wettability with the recording medium or the substrate. Among the surfactants, acetylene glycol-based surfactants, silicone-based surfactants, and fluorine-based surfactants can be preferably used.

[0118] The acetylene glycol-based surfactant is not particularly limited. For example, Surfyl Nole 104, 104E, 104H, 104A, 104BC, 104DPM, 104PA, 104PG-50, 104S, 420, 440, 465, 485, SE, SE-F, 504, 61, DF37, CT111, CT121, CT131, CT136, TG, GA, DF110D (all of the above are product names, manufactured by Air Products & Chemicals), Orfin B, Y, P, A, STG, SPC, E1004, E1010, PD-001, PD-002W, PD-003, PD-004, EXP.4001, EXP.4036, EXP.4051, AF-103, AF-104, AK-02, SK-14, AE-3 (all of the above are product names, manufactured by Nissin Chemical Industry Co., Ltd.), Acetylenol E00, E00P, E40, E100 (all of the above are product names, manufactured by Kawaken Fine Chemicals Co., Ltd.) may be mentioned.

[0119] As the silicone surfactant, although not particularly limited, polysiloxane compounds are preferably mentioned. As the polysiloxane compound, although not particularly limited, for example, polyether-modified organosiloxane may be mentioned. As commercially available products of the polyether-modified organosiloxane, for example, BYK-306, BYK-307, BYK-333, BYK-341, BYK-345, BYK-346, BYK-348 (the above product names, manufactured by Big Chemie Japan), KF-351A, KF-352A, KF-353, KF-354L, KF-355A, KF-615A, KF-945, KF-640, KF-642, KF-643, KF-6020, X-22-4515, KF-6011, KF-6012, KF-6015, KF-6017 (the above product names, manufactured by Shin-Etsu Chemical Co., Ltd.) may be mentioned.

[0120] As the fluorine surfactant, it is preferable to use a fluorine-modified polymer. Specific examples include BYK-3440 (manufactured by Big Chemie Japan), Surfron S-241, S-242, S-243 (the above product names, manufactured by AGC Seimi Chemical Co., Ltd.), Ftergent 215M (manufactured by Neos), etc.

[0121] When the ink composition contains a surfactant, a plurality of types may be contained. When the ink composition contains a surfactant, the content is preferably 0.1% by mass or more and 2.0% by mass or less, more preferably 0.2% by mass or more and 1.5% by mass or less, and still more preferably 0.3% by mass or more and 1.0% by mass or less with respect to the total mass.

[0122] (5) Additives The ink composition may contain ureas, amines, saccharides, etc. as additives. Examples of ureas include urea, ethylene urea, tetramethyl urea, thiourea, 1,3-dimethyl-2-imidazolidinone, etc., and betaines (trimethylglycine, triethylglycine, tripropylglycine, triisopropylglycine, N,N,N-trimethylalanine, N,N,N-triethylalanine, N,N,N-triisopropylalanine, N,N,N-trimethylmethylalanine, carnitine, acetylcarnitine, etc.).

[0123] Examples of amines include diethanolamine, triethanolamine, triisopropanolamine, etc. Ureas and amines may function as pH adjusters.

[0124] Examples of saccharides include glucose, mannose, fructose, ribose, xylose, arabinose, galactose, aldonic acid, glucitol (sorbitol), maltose, cellobiose, lactose, sucrose, trehalose, and maltotriose, etc.

[0125] (6) Wax The ink composition may contain wax. Since wax has the function of imparting smoothness to the image formed by the ink composition, peeling of the image, etc. can be reduced. Examples of the components constituting the wax include carnauba wax, candelilla wax, beeswax, rice wax , plant and animal waxes such as lanolin; petroleum waxes such as paraffin wax, microcrystalline wax, polyethylene wax, oxidized polyethylene wax, petrolatum; mineral waxes such as montan wax, ozokerite; synthetic waxes such as carbon wax, Hostawax, polyolefin wax, stearic amide; natural and synthetic wax emulsions such as α-olefin maleic anhydride copolymer and compounded waxes can be used alone or in combination of multiple types.

[0126] As the wax, commercially available products can also be used as they are. For example, Nopcoat PEM-17 (trade name, manufactured by San Nopco Ltd.), Chem Pearl W4005 (trade name, manufactured by Mitsui Chemicals, Inc.), AQUACER 515, 539, 593 (above trade names, manufactured by BYK-Chemie Japan Co., Ltd.) and the like can be mentioned.

[0127] (7) Others The ink composition used in the inkjet recording method according to this embodiment may further contain components such as preservatives, fungicides, rust preventives, chelating agents, viscosity modifiers, antioxidants, and antifungal agents, if necessary.

[0128] 1.1.7. Physical properties of the ink composition, etc. The viscosity of the ink composition at 20°C is preferably 2 mPa·s or more and 15 mPa·s or less. When the viscosity of the ink composition at 20°C is within the above range, it becomes more suitable for the inkjet method, the ink composition is discharged more appropriately from the nozzle, and the flight curve and scattering of the ink composition can be further reduced, so it can be more suitably used in an inkjet recording apparatus.

[0129] The ink composition can be obtained by mixing the above-mentioned components in an appropriate order and, if necessary, removing impurities by filtration or the like. As a method for mixing each component, a method of adding materials to a container equipped with a stirring device such as a mechanical stirrer or a magnetic stirrer and stirring and mixing is preferably used.

[0130] 1.2. Treatment liquid The processing liquid constituting the ink set according to this embodiment contains a flocculant. Hereinafter, each component contained in the processing liquid will be described.

[0131] 1.2.1. Flocculant The processing liquid contains a flocculant that aggregates the components of the ink composition. The above-described ink composition has excellent aggregability of the maleic acid-based resin by the flocculant of the processing liquid, and an image with excellent image quality can be obtained.

[0132] The flocculant has a function of aggregating at least one of these dispersions by acting on the dispersibility of components such as maleic acid-based resin, pigment, and water-dispersible resin contained in the ink composition. The degree of aggregation of the dispersion by the flocculant varies depending on the type of the flocculant and the target, and can be adjusted. By such an aggregation action, for example, the color development of the image can be enhanced and / or the fixing property of the image can be enhanced.

[0133] The flocculant is not particularly limited, and examples thereof include metal salts, acids, cationic compounds, etc. As the cationic compound, a cationic resin (cationic polymer), a cationic surfactant, etc. can be used. Among these, as the metal salt, a polyvalent metal salt is preferable, and as the cationic compound, a cationic resin is preferable. Examples of the acid include organic acids and inorganic acids, and organic acids are preferable. Therefore, it is preferable that the flocculant is selected from a cationic resin, an organic acid, and a polyvalent metal salt in terms of particularly excellent image quality, rubbing resistance, gloss, etc. preferred.

[0134] The metal salt is preferably a polyvalent metal salt, but metal salts other than polyvalent metal salts can also be used. Among these flocculants, it is preferable to use at least one selected from metal salts and organic acids in terms of excellent reactivity with the components contained in the ink. Among the cationic compounds, it is preferable to use a cationic resin in terms of easy solubility in the processing liquid. Also, a plurality of types of flocculants can be used in combination.

[0135] A polyvalent metal salt is a compound composed of metal ions with a valence of 2 or higher and anions. Examples of metal ions with a valence of 2 or higher include ions such as calcium, magnesium, copper, nickel, zinc, barium, aluminum, titanium, strontium, chromium, cobalt, and iron. Among these metal ions constituting the polyvalent metal salt, at least one of calcium ions and magnesium ions is preferable from the viewpoint of excellent aggregability of the components of the ink.

[0136] The anion constituting the polyvalent metal salt is an inorganic ion or an organic ion. That is, the polyvalent metal salt in the present invention consists of an inorganic ion or an organic ion and a polyvalent metal. Examples of such inorganic ions include chloride ions, bromide ions, iodide ions, nitrate ions, sulfate ions, hydroxide ions, and the like. Examples of organic ions include organic acid ions, such as carboxylic acid ions.

[0137] Note that the polyvalent metal compound is preferably an ionic polyvalent metal salt. In particular, when the polyvalent metal salt is a magnesium salt or a calcium salt, the stability of the treatment liquid becomes better. Also, as the counter ion of the polyvalent metal, either an inorganic acid ion or an organic acid ion may be used.

[0138] Specific examples of the above-mentioned polyvalent metal salts include calcium carbonate such as heavy calcium carbonate and light calcium carbonate, calcium nitrate, calcium chloride, calcium sulfate, magnesium sulfate, calcium hydroxide, magnesium chloride, magnesium carbonate, barium sulfate, barium chloride, zinc carbonate, zinc sulfide, aluminum silicate, calcium silicate, magnesium silicate, copper nitrate, calcium acetate, magnesium acetate, aluminum acetate, calcium propionate, magnesium propionate, aluminum propionate, calcium lactate, magnesium lactate, aluminum lactate, etc. These polyvalent metal salts may be used alone or in combination of two or more. Among these, at least any one of magnesium sulfate, calcium nitrate, aluminum lactate, and calcium propionate is preferable in terms of obtaining sufficient solubility in water. Incidentally, these metal salts may have water of hydration in the raw material form.

[0139] Examples of metal salts other than polyvalent metal salts include monovalent metal salts such as sodium salts and potassium salts, for example, sodium sulfate, potassium sulfate, etc.

[0140] Examples of organic acids preferably include poly(meth)acrylic acid, formic acid, acetic acid, propionic acid, glycolic acid, oxalic acid, malonic acid, malic acid, maleic acid, ascorbic acid, succinic acid, glutaric acid, adipic acid, fumaric acid, citric acid, tartaric acid, lactic acid, pyruvic acid, pyrrolidonecarboxylic acid, pyronecarboxylic acid, pyrrolecarboxylic acid, furancarboxylic acid, pyridinecarboxylic acid, coumaric acid, thiophenecarboxylic acid, nicotinic acid, or derivatives of these compounds, or salts thereof, etc. Organic acids may be used alone or in combination of two or more. Metal salts that are salts of organic acids are included in the above-mentioned metal salts.

[0141] Examples of inorganic acids include sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, etc. Inorganic acids may be used alone or in combination of two or more.

[0142] Examples of the cationic resin (cationic polymer) include cationic urethane resins, cationic olefin resins, cationic amine resins, cationic surfactants, and the like.

[0143] As the cationic urethane resin, commercially available products can be used. For example, Hydran CP-7010, CP-7020, CP-7030, CP-7040, CP-7050, CP-7060, CP-7610 (trade names, manufactured by Dainippon Ink and Chemicals, Inc.), Superflex 600, 610, 620, 630, 640, 650 (trade names, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Urethane Emulsion WBR-2120C, WBR-2122C (trade names, manufactured by Daisheng Fine Chemical Co., Ltd.), etc. can be used.

[0144] The cationic olefin resin has an olefin such as ethylene or propylene in its structural skeleton, and known ones can be appropriately selected and used. Further, the cationic olefin resin may be in an emulsion state dispersed in a solvent containing water, an organic solvent, or the like. As the cationic olefin resin, commercially available products can be used. For example, Arrow Base CB-1200, CD-1200 (trade names, manufactured by Unitika Ltd.), etc. can be mentioned.

[0145] The cationic amine resin (cationic polymer) may be any one having an amino group in its structure, and known ones can be appropriately selected and used. For example, polyamine resins, polyamide resins, polyallylamine resins, and the like can be mentioned. The polyamine resin is a resin having an amino group in the main skeleton of the resin. The polyamide resin is a resin having an amide group in the main skeleton of the resin. The polyallylamine resin is a resin having a structure derived from an allyl group in the main skeleton of the resin.

[0146] In addition, examples of the cationic polyamine resin include Unisen KHE103L (hexamethylenediamine / epichlorohydrin resin, pH of 1% aqueous solution is about 5.0, viscosity is 20 to 50 (mPa·s), aqueous solution with a solid content concentration of 50% by mass) and Unisen KHE104L (dimethylamine / epichlorohydrin resin, pH of 1% aqueous solution is about 7.0, viscosity is 1 to 10 (mPa·s), aqueous solution with a solid content concentration of 20% by mass) manufactured by Senka Corporation. Further, specific examples of commercially available cationic polyamine resins include FL-14 (manufactured by SNF), Arafix 100, 251S, 255, 255LOX (manufactured by Arakawa Chemical Industries), DK-6810, 6853, 6885; WS-4010, 4011, 4020, 4024, 4027, 4030 (manufactured by Starlight PMC), Papigen P-105 (manufactured by Senka), Sumirex Resin 650(30), 675A, 6615, SLX-1 (manufactured by Tago Chemical Industry), Cation Master (registered trademark) PD-1, 7, 30, A, PDT-2, PE-10, PE-30, DT-EH, EPA-SK01, TMHMDA-E (manufactured by Yokkaichi Gosei), Jet Fix 36N, 38A, 5052 (manufactured by Satoda Chemical Industry).

[0147] Examples of the polyallylamine resin include, for example, polyallylamine hydrochloride, polyallylamine amide sulfate, allylamine hydrochloride / diallylamine hydrochloride copolymer, allylamine acetate / diallylamine acetate copolymer, allylamine acetate / diallylamine acetate copolymer, allylamine hydrochloride / dimethylallylamine hydrochloride copolymer, allylamine / dimethylallylamine copolymer, polydiallylamine hydrochloride, polymethyldiallylamine hydrochloride, polymethyldiallylamine amide sulfate, polymethyldiallylamine acetate, polydiallyldimethylammonium chloride, diallylamine acetate / sulfur dioxide copolymer, diallylmethylethylammonium ethyl sulfate / sulfur dioxide copolymer, methyldiallylamine hydrochloride / sulfur dioxide copolymer, diallyldimethylammonium chloride / sulfur dioxide copolymer, diallyldimethylammonium chloride / acrylamide co Examples of the polymer and the like can be mentioned.

[0148] Examples of cationic surfactants include primary, secondary, and tertiary amine salt type compounds, alkylamine salts, dialkylamine salts, aliphatic amine salts, benzalkonium salts, quaternary ammonium salts, quaternary alkylammonium salts, alkylpyridinium salts, sulfonium salts, phosphonium salts, onium salts, imidazolinium salts, and the like. Specifically, for example, hydrochlorides, acetates, etc. of laurylamine, coconut amine, rosin amine, etc., lauryltrimethylammonium chloride, cetyltrimethylammonium chloride, benzyltributylammonium chloride, benzalkonium chloride, dimethylethyllaurylammonium ethyl sulfate, dimethylethyloctylammonium ethyl sulfate, trimethyllaurylammonium hydrochloride, cetylpyridinium chloride, cetylpyridinium bromide, dihydroxyethyllaurylamine, decyldimethylbenzylammonium chloride, dodecyldimethylbenzylammonium chloride, tetradecyldimethylammonium chloride, hexadecyldimethylammonium chloride, octadecyldimethylammonium chloride, and the like can be mentioned. Note that the cationic surfactant functions as a flocculant described later, and may be contained in the ink composition. However, it is more preferable that the cationic surfactant is contained as a flocculant in the treatment liquid.

[0149] A plurality of these flocculants may be used. Further, among these flocculants, if at least one of polyvalent metal salts, organic acids, and cationic resins is selected, the flocculation action is better, so that a higher-quality (especially with good color development) image can be formed.

[0150] In the treatment liquid, the total content of the flocculant is, for example, 0.1% by mass or more and 20% by mass or less, preferably 1% by mass or more and 20% by mass or less, and more preferably 2% by mass or more and 15% by mass or less, based on the total mass of the treatment liquid. Even when the flocculant is shared as a solution or a dispersion, it is preferable that the content of the solid component is within the above range. If the content of the flocculant is 1% by mass or more, the ability of the flocculant to aggregate the components contained in the ink can be sufficiently obtained. Also, when the content of the flocculant is 30% by mass or less, the solubility and dispersibility of the flocculant in the treatment liquid become better, and the storage stability of the treatment liquid and the like can be improved.

[0151] Further, even when the hydrophobicity of the organic solvent contained in the treatment liquid is high, from the viewpoint that the solubility of the flocculant in the treatment liquid is good, it is preferable to use a flocculant having a solubility of 1 g or more in 100 g of water at 25°C, and more preferably a flocculant having a solubility in the range of 3 g or more and 80 g or less.

[0152] 1.2.2. Other Components The treatment liquid may contain components such as water-soluble low-molecular organic compounds, organic solvents, surfactants, water, waxes, additives, antiseptics / mildew inhibitors, rust preventives, chelating agents, antioxidants, and antifungal agents, in addition to the flocculant, as long as the functions are not impaired. Since these components are the same as those of the above-described ink composition, detailed descriptions are omitted. The treatment liquid is preferably an aqueous treatment liquid.

[0153] 1.2.3. Physical Properties of the Treatment Liquid, etc. The viscosity of the treatment liquid at 20°C is preferably 2 mPa·s or more and 15 mPa·s or less. When the viscosity of the treatment liquid at 20°C is within the above range, it is suitable for the inkjet method, the treatment liquid can be appropriately ejected from the nozzle, and the flight curve and scattering of the treatment liquid can be reduced, so it can be suitably used in an inkjet recording apparatus.

[0154] The treatment liquid can be obtained by mixing the above-mentioned respective components in an appropriate order and, if necessary, performing filtration or the like to remove impurities. As a method for mixing the respective components, a method of adding materials to a container equipped with a stirring device such as a mechanical stirrer or a magnetic stirrer and stirring and mixing them is preferable. It is used for

[0155] 1.3. Other configurations As long as the ink set of the present embodiment includes the above-mentioned ink composition and treatment liquid, it may include other ink compositions. The ink set may include, for example, a plurality of the above-mentioned ink compositions or treatment liquids, or may further include an ink composition other than the above, and may include, for example, a clear ink composition that does not contain a pigment.

[0156] 1.4. Effects According to the ink set of the present embodiment, since the maleic acid-based resin of the ink composition is liable to be affected by the action of the flocculant of the treatment liquid, when forming an image by bringing the treatment liquid and the ink composition into contact with each other, aggregation unevenness hardly occurs in the image, and a high-quality image can be formed. Furthermore, since the ink composition contains a water-dispersible resin, it is possible to suppress a decrease in the rubbing resistance of the image caused by the water-solubility of the maleic acid-based resin, and the rubbing resistance of the image can be further improved by the synergistic action of the maleic acid-based resin and the water-dispersible resin.

[0157] 2. Recording method The recording method of the present embodiment includes an ink adhesion step of discharging the ink composition by an inkjet method and adhering it to a recording medium, and a treatment liquid adhesion step of adhering the treatment liquid to the recording medium, using the above-mentioned ink set.

[0158] 2.1. Recording medium The recording medium for forming an image by the recording method according to this embodiment may or may not have a recording surface that absorbs liquids such as an ink composition and a processing liquid. Therefore, there is no particular limitation on the recording medium. For example, liquid-absorbent recording media such as paper and cloth, liquid-low-absorbent recording media such as printing paper, and liquid-non-absorbent recording media such as metal, glass, film, and polymer can be mentioned. However, the excellent effect of the recording method of this embodiment becomes more prominent when an image is recorded on a liquid-low-absorbent or liquid-non-absorbent recording medium. That is, according to the recording method of this embodiment, even on a low-absorbent recording medium or a non-absorbent recording medium where aggregation unevenness is relatively likely to occur, a high-quality image with good abrasion resistance can be formed.

[0159] A liquid-low-absorbent or liquid-non-absorbent recording medium refers to a recording medium that has the property of not absorbing any liquid or hardly absorbing any liquid. Quantitatively, a liquid-non-absorbent or liquid-low-absorbent recording medium refers to "a recording medium with a water absorption amount of 10 mL / m or less from the start of contact to 30 msec in the Bristow method". 1 / 2 up to 2 This Bristow method is the most popular method for measuring the liquid absorption amount in a short time and is also adopted by the Japan Pulp and Paper Technical Association (JAPAN TAPPI). The details of the test method are described in Standard No. 51, "Paper and Paperboard - Liquid Absorbency Test Method - Bristow Method" of "JAPAN TAPPI Paper and Pulp Test Methods 2000 Edition". On the other hand, a liquid-absorbent recording medium refers to a recording medium that does not fall under liquid-non-absorbent and liquid-low-absorbent. In this specification, liquid-low-absorbent and liquid-non-absorbent may be simply referred to as low-absorbent and non-absorbent.

[0160] Examples of non-liquid-absorbent recording media include films and plates made of plastics such as polyvinyl chloride, polyethylene, polypropylene, and polyethylene terephthalate (PET), plates made of metals such as iron, silver, copper, and aluminum, or metal plates and plastic films manufactured by vapor deposition of these various metals, plates made of alloys such as stainless steel and cast iron, etc. Also, those in which plastic is coated on a substrate such as paper, those in which a plastic film is adhered to a substrate such as paper, and plastic films that do not have an absorption layer (reception layer). Examples of the plastics mentioned here include polyvinyl chloride, polyethylene terephthalate, polycarbonate, polystyrene, polyurethane, polyethylene, polypropylene, etc.

[0161] Examples of liquid-low-absorbent recording media include recording media provided with a coating layer (reception layer) for receiving liquid on the surface. For example, as those with a paper substrate, printed book paper can be mentioned. As those with a plastic film substrate, those in which a hydrophilic polymer or the like is coated on the surface of polyvinyl chloride, polyethylene terephthalate, polycarbonate, polystyrene, polyurethane, polyethylene, polypropylene, etc., and those in which particles such as silica and titanium are coated together with a binder can be mentioned.

[0162] Examples of liquid-absorbent recording media are not particularly limited. For example, from general papers such as electrophotographic papers with high liquid permeability, inkjet papers (inkjet dedicated papers equipped with an ink absorption layer composed of silica particles or alumina particles, or an ink absorption layer composed of a hydrophilic polymer such as polyvinyl alcohol (PVA) or polyvinylpyrrolidone (PVP)), to art papers, coated papers, cast papers, etc. used for general offset printing with relatively low liquid permeability. Furthermore, fabrics, non-woven fabrics, etc. can also be exemplified as liquid-absorbent recording media.

[0163] Note that the recording medium may be colorless and transparent, translucent, colored and transparent, colored and opaque, achromatic and opaque, etc. Further, the recording medium may itself be colored, translucent or transparent.

[0164] 2.2. Ink adhesion step The ink adhesion step may be performed by any method as long as the ink composition is adhered while relatively scanning the recording head and the recording medium. For example, it is preferable to use an inkjet method in which the recording head is an inkjet head and the ink composition is ejected from the inkjet head. In this way, printing in small quantities and of multiple types can be efficiently performed with a small device. In addition to the inkjet method, ink may be adhered by an analog printing method or the like.

[0165] The ink adhesion step can be easily performed by an inkjet recording apparatus. Details of the inkjet recording apparatus will be described later. An ink composition that is ejected from an inkjet head by the inkjet method and used for recording is referred to as an inkjet ink composition.

[0166] 2.3. Treatment liquid adhesion step The treatment liquid adhesion step is a step of adhering the treatment liquid to the recording medium. As a method of adhering the treatment liquid to the recording medium, a non-contact method, a contact method, or a combination thereof can be used, such as an inkjet method, a method by coating, a method of applying the treatment liquid to the recording medium using various sprays, a method of immersing the recording medium in the treatment liquid and then applying it, or a method of applying the treatment liquid to the recording medium with a brush or the like.

[0167] The treatment liquid adhesion step may be performed by an inkjet recording apparatus. In this way, it is more preferable because the treatment liquid and the ink composition can be adhered to the recording medium with one inkjet recording apparatus. Details of the inkjet recording apparatus will be described later.

[0168] 2.4. Other steps In addition to the above ink adhesion step and treatment liquid adhesion step, the recording method of this embodiment may include a heating step, a lamination step, and the like.

[0169] 2.4.1. Heating Step (Primary Heating Step) The ink adhesion step of the recording method of this embodiment may include a heating step of heating the composition adhered to the recording medium. In this way, an image with high image quality and good rub resistance can be obtained, and the effect of high recording speed can be obtained more significantly. Such a heating step is called a primary heating step. The primary heating step quickly heats and dries the ink adhered to the recording medium. It is to adhere ink to the heated recording medium or to heat the recording medium at an early stage after the ink adheres to the recording medium, and heating of the ink droplet starts within approximately 1 second after the ink droplet adheres to the recording medium.

[0170] The primary heating step may include a step of heating the recording medium before or during the treatment liquid adhesion step and / or the ink adhesion step. The primary heating step can be performed by means of drying using a heating mechanism. As means for drying using a heating mechanism, means for blowing normal temperature air or warm air to the recording medium (blowing type), means for irradiating radiation (such as infrared rays) that generates heat to the recording medium (radiation type), a member that contacts the recording medium and transfers heat to the recording medium (conduction type), and combinations of two or more of these means can be mentioned. When having a primary heating step, it is more preferably performed in a radiation type among these. The primary heating step using a heating mechanism immediately promotes drying of the composition adhered to the recording medium.

[0171] The primary heating step is preferably performed by a heating mechanism arranged at a position immediately before or immediately after each composition adheres as described later. In this way, heating of the inkjet head is suppressed, so the clogging resistance is more excellent and an improvement in ejection stability can be expected.

[0172] The surface temperature of the recording medium during attachment in the primary attachment step of the ink composition is preferably 45.0 °C or lower, more preferably 43.0 °C or lower, still more preferably 40.0 °C or lower, even more preferably 38.0 °C or lower, particularly preferably 35.0 °C or lower, still more preferably 32.0 °C or lower, more preferably 30.0 °C or lower, and particularly preferably 28.0 °C or lower. On the other hand, the lower limit is preferably 20.0 °C or higher, more preferably 23.0 °C or higher, still more preferably 25.0 °C or higher, particularly preferably 28.0 °C or higher, still more preferably 30.0 °C or higher, and more preferably 32.0 °C or higher.

[0173] This temperature is the surface temperature of the portion of the recording surface of the recording medium that has received the attachment of the composition in the attachment step, and is the highest temperature in the attachment step in the recording area. When the surface temperature is within the above range or lower, it is more preferable in terms of reducing clogging and high gloss. When it is within the above range or higher, it is more preferable in terms of the durability of the image and the good spread of the composition and excellent image quality.

[0174] The surface temperature of the recording medium during attachment can be made relatively high by performing the primary heating step using a heating mechanism, and can be made relatively low by not performing it.

[0175] When performing the primary heating step, it can be performed simultaneously with one or more of the above-described attachment steps. When the primary heating step is performed simultaneously with the attachment step, the surface temperature of the recording medium is preferably 43.0 °C or lower, and more preferably 40.0 °C or lower.

[0176] (Post-heating step) The inkjet recording method according to the present embodiment may further include a post-heating step of heating the recording medium after the primary heating step after each of the above attachment steps. The post-heating step is also referred to as a secondary heating step. The post-heating step starts heating after more than about 1 second after all the ink attached to a certain area of the recording medium has been attached.

[0177] The post-heating process can be carried out using appropriate heating means. The post-heating process is performed, for example, by an after-heater (corresponding to the heating heater 5 in the example of the inkjet recording apparatus 1 described later). Further, the heating means is not limited to the heating means provided in the inkjet recording apparatus, and other drying means may be used. Since the obtained image can be dried and more sufficiently fixed, for example, the recording material can be brought into a state where it can be used early.

[0178] The temperature of the recording medium in this case is not particularly limited, but can be set, for example, in view of the Tg or the like of the resin component constituting the resin particles contained in the recording material. When considering the Tg of the resin component constituting the water-dispersible resin or wax, it is preferably set 5.0 °C or more, preferably 10.0 °C or more higher than the Tg of the resin component.

[0179] The surface temperature of the recording medium reached by the heating in the post-heating process is 30.0 °C or more and 120.0 °C or less, preferably 40.0 °C or more and 100.0 °C or less, more preferably 50.0 °C or more and 95 °C or less, and still more preferably 70 °C or more and 90 °C or less. The surface temperature of the recording medium reached by the heating in the post-heating process is particularly preferably 80 °C or more. If the temperature of the recording medium is within this range, the resin particles contained in the recording material can be made into a film and flattened, and the obtained image can be dried and more sufficiently fixed.

[0180] 2.4.2. Laminating process The recording medium obtained by the above recording method may be used after being laminated on the recording surface. The lamination process for laminating the recording medium can be performed by laminating a film, such as by attaching the film to the recording surface of the recording medium on which the ink composition is adhered. Also, although not particularly limited, a known adhesive may be attached to the recording surface of the recording medium, and the film may be attached thereto, or the film with the adhesive attached may be attached to the recording surface of the recording medium. Alternatively, using a molten resin in which the film is melted, the molten resin can be extruded onto the recording surface of the recording medium and formed into a film on the recording surface of the recording medium. As a material such as a film used for lamination, for example, a resin film can be used. Laminating the recording medium is preferable in that the abrasion resistance of the recording medium becomes better and the protectiveness is excellent when the recording medium is subjected to excessive handling such as being hit by a solid object. Also, after attaching the recording medium and the film, it is preferable to further heat or press at room temperature to ensure sufficient adhesion.

[0181] 2.4.3. Other Matters The treatment liquid adhesion step is more preferably performed prior to the ink adhesion step. By doing so, the aggregating agent contained in the treatment liquid can sufficiently act on the ink composition. Also, the recording method of the present embodiment may further include a step of attaching one or more of the treatment liquid and the ink composition to the recording medium as necessary. Moreover, there are no restrictions on the order and number of these steps, and they can be appropriately performed as necessary. In this case, the treatment liquid and each ink composition may or may not be attached to the same area on the recording medium. According to the recording method of the present embodiment, an image with high image quality and good abrasion resistance can be formed.

[0182] 3. Inkjet Recording Apparatus An example of an inkjet recording apparatus suitable for the recording method according to the present embodiment will be described with reference to the drawings. The inkjet recording apparatus includes an inkjet head that performs the ink adhesion step of the ink composition and a primary heating mechanism, and can perform the above-described recording method.

[0183] FIG. 1 is a schematic cross-sectional view schematically showing an inkjet recording apparatus. FIG. 2 is a perspective view showing an example of the configuration around the carriage of the inkjet recording apparatus 1 of FIG. 1. As shown in FIGS. 1 and 2 As shown, the inkjet recording apparatus 1 includes an inkjet head 2, an IR heater 3, a platen heater 4, a heating heater 5, a cooling fan 6, a preheater 7, a ventilation fan 8, a carriage 9, a platen 11, a carriage movement mechanism 13, a conveying means 14, and a control unit CONT. The operation of the entire inkjet recording apparatus 1 is controlled by the control unit CONT shown in FIG. 2

[0184] The inkjet head 2 is configured to perform recording on the recording medium M by discharging and attaching a processing liquid and an ink composition from the nozzles of the inkjet head 2. In the present embodiment, the inkjet head 2 is a serial type inkjet head, and scans the recording medium M a plurality of times in the main scanning direction relatively to attach ink to the recording medium M. The inkjet head 2 is mounted on the carriage 9 shown in FIG. 2. The inkjet head 2 is scanned a plurality of times in the main scanning direction relatively to the recording medium M by the operation of the carriage movement mechanism 13 that moves the carriage 9 in the medium width direction of the recording medium M. The medium width direction is the main scanning direction of the inkjet head 2. Scanning in the main scanning direction is also referred to as main scanning

[0185] Here, the main scanning direction is the direction in which the carriage 9 equipped with the inkjet head 2 moves. In FIG. 1, it is the direction intersecting the sub-scanning direction, which is the conveyance direction of the recording medium M indicated by the arrow SS. In FIG. 2, the width direction of the recording medium M, that is, the direction represented by S1 - S2, is the main scanning direction MS, and the direction represented by T1→T2 is the sub-scanning direction SS. Note that in one scan, the scanning is performed in the main scanning direction, that is, either in the direction of arrow S1 or arrow S2. Then, by repeatedly performing the main scanning of the inkjet head 2 and the sub-scanning of the conveyance of the recording medium M a plurality of times, recording is performed on the recording medium M. That is, the treatment liquid adhesion step and the ink adhesion step are performed by a plurality of main scans in which the inkjet head 2 moves in the main scanning direction and a plurality of sub-scans in which the recording medium M moves in the sub-scanning direction intersecting the main scanning direction.

[0186] The cartridges 12 that supply the ink composition and the treatment liquid to the inkjet head 2 respectively include a plurality of independent cartridges. The cartridge 12 is detachably attached to the carriage 9 equipped with the inkjet head 2. Each of the plurality of cartridges is filled with a different type of ink composition or treatment liquid, and the ink composition and the treatment liquid are supplied from the cartridge 12 to each nozzle. Note that in the present embodiment, an example in which the cartridge 12 is attached to the carriage 9 is shown, but it is not limited thereto, and it may be provided at a location other than the carriage 9 and supplied to each nozzle by a supply pipe (not shown).

[0187] A conventionally known method can be used for the ejection of the inkjet head 2. In the present embodiment, a method of ejecting droplets by utilizing the vibration of a piezoelectric element, that is, an ejection method of forming ink droplets by the mechanical deformation of an electrostrictive element, is used.

[0188] The inkjet recording apparatus 1 includes an IR heater 3 and a platen heater 4 for heating a recording medium M when an ink composition is ejected from the inkjet head 2. The temporary heating process can be performed by the IR heater 3 or the platen heater 4. Further, in the present embodiment, when drying the recording medium M in the primary heating process, a ventilation fan 8 or the like described later can be used.

[0189] When the IR heater 3 is used, the recording medium M can be heated in a radiation manner by infrared radiation from the inkjet head 2 side. As a result, the inkjet head 2 is also likely to be heated at the same time, but the temperature can be increased without being affected by the thickness of the recording medium M as compared with the case where the recording medium M is heated from the back surface such as the platen heater 4. Also, various fans (for example, the ventilation fan 8) for drying the ink on the recording medium M by blowing warm air or air at the same temperature as the environment onto the recording medium M may be provided.

[0190] The platen heater 4 can heat the recording medium M via the platen 11 at a position facing the inkjet head 2 so that the processing liquid or ink composition ejected by the inkjet head 2 can be dried early when it adheres to the recording medium M. The platen heater 4 can heat the recording medium M in a conduction manner, and in the recording method of the present embodiment, the ink composition can be adhered to the recording medium M heated thereby (primary heating). Therefore, the ink composition can be fixed early on the recording medium M, and the image quality can be improved.

[0191] The heating heater 5 is a heater for secondary heating or secondary drying that dries and solidifies the processing liquid or ink composition adhered to the recording medium M. The heating heater 5 can be used in the post-heating process. By heating the recording medium M on which an image is recorded, the moisture and the like contained in the ink composition evaporate and disperse more quickly, and an ink film is formed by the resin contained in the ink composition. In this way, the ink film firmly adheres or adheres on the recording medium M and has excellent film-forming properties, and an excellent high-quality image can be obtained in a short time.

[0192] The inkjet recording apparatus 1 may have a cooling fan 6. After drying the ink composition recorded on the recording medium M, by cooling the ink composition on the recording medium M with the cooling fan 6, an ink coating film can be formed with good adhesion on the recording medium M.

[0193] Further, the inkjet recording apparatus 1 may include a pre-heater 7 that pre-heats the recording medium M before the ink composition is adhered to the recording medium M. Furthermore, the inkjet recording apparatus 1 may include a ventilation fan 8 so that the ink composition adhered to the recording medium M dries more efficiently.

[0194] Below the carriage 9, there are provided a platen 11 that supports the recording medium M, a carriage moving mechanism 13 that relatively moves the carriage 9 with respect to the recording medium M, and a conveying means 14 that is a roller for conveying the recording medium M in the sub-scanning direction. The operations of the carriage moving mechanism 13 and the conveying means 14 are controlled by the control unit CONT.

[0195] Figure 3 is a functional block diagram of the inkjet recording apparatus 1. The control unit CONT is a control unit for controlling the inkjet recording apparatus 1. The interface unit 101 (I / F) is for transmitting and receiving data between the computer 130 (COMP) and the inkjet recording apparatus 1. The CPU 102 is an arithmetic processing unit for controlling the entire inkjet recording apparatus 1. The memory 103 (MEM) is for securing an area for storing the program of the CPU 102, a work area, etc. The CPU 102 controls each unit by means of the unit control circuit 104 (UCTRL). Note that the detector group 121 (DS) monitors the situation inside the inkjet recording apparatus 1, and based on the detection results, the control unit CONT controls each unit.

[0196] The conveyance unit 111 (CONVU) controls the sub-scanning (conveyance) of inkjet recording. Specifically, it controls the conveyance direction and conveyance speed of the recording medium M. Specifically, it controls the conveyance direction and conveyance speed of the recording medium M by controlling the rotation direction and rotation speed of the conveyance roller driven by a motor.

[0197] The carriage unit 112 (CARU) controls the main scanning (pass) of inkjet recording. Specifically, it reciprocates the inkjet head 2 in the main scanning direction. The carriage unit 112 includes a carriage 9 on which the inkjet head 2 is mounted and a carriage moving mechanism 13 for reciprocating the carriage 9.

[0198] The head unit 113 (HU) controls the ejection amount of the ink composition from the nozzles of the inkjet head 2. For example, when the nozzles of the inkjet head 2 are driven by piezoelectric elements, it controls the operation of the piezoelectric elements at each nozzle. The head unit 113 controls the timing of each ink attachment, the dot size of the ink composition, etc. Also, by combining the control of the carriage unit 112 and the head unit 113, the attachment amount of the ink composition per scan is controlled.

[0199] The drying unit 114 (DU) controls the temperatures of various heaters such as the IR heater 3, the preheater 7, the platen heater 4, and the heating heater 5.

[0200] The above inkjet recording apparatus 1 alternately repeats the operation of moving the carriage 9 mounting the inkjet head 2 in the main scanning direction and the conveyance operation (sub-scanning). At this time, when performing each pass, the control unit CONT controls the carriage unit 112 to move the inkjet head 2 in the main scanning direction, and controls the head unit 113 to eject droplets of the ink composition from a predetermined nozzle hole of the inkjet head 2, and attach the droplets of the ink composition to the recording medium M. Further, the control unit CONT controls the conveyance unit 111 to convey the recording medium M in the conveyance direction at a predetermined conveyance amount (feed amount) during the conveyance operation.

[0201] In the inkjet recording apparatus 1, by repeating the main scanning (pass) and the sub-scanning (conveyance operation), the recording area to which a plurality of droplets are attached is gradually conveyed. Then, the afterheater 5 dries the droplets attached to the recording medium M, and the image is completed. Thereafter, the completed recording may be wound into a roll by a winding mechanism or conveyed by a flatbed mechanism.

[0202] FIG. 4 is an example of a flowchart showing the processing performed when recording is performed in the inkjet recording apparatus. When starting the recording, the control unit of the inkjet recording apparatus determines the recording mode in step 400. The recording mode is a recording mode in which details of recording such as the nozzle arrangement, the ejection amount, the mode of overprinting, the operation of the inkjet head during recording, the operation of the recording medium, and the control of the heating mechanism are defined. The details of the recording also include the number of passes of the recording (the number of times of performing the main scanning on the same recording area of the recording medium).

[0203] The determination of the recording mode is determined by an input signal input from an external device such as a computer to the inkjet recording apparatus, or by user input information to a user input unit provided in the inkjet recording apparatus. Here, the input signal from the external device and the user input information may be information directly specifying the recording mode, or may be information related to recording, such as information on the type of recording medium to be recorded, the specification of the recording speed, or the specification of the image quality. Also, the information related to recording is not limited to these. In the latter case, the inkjet recording apparatus records correspondence information in the inkjet recording apparatus such as a control unit, which defines a recording mode corresponding to the information related to recording in advance, and determines the recording mode by referring to the correspondence information. Or it may be determined using AI technology (artificial intelligence technology).

[0204] In step S401, the determined recording mode is discriminated. In step S402 or S403, according to the determined recording mode, the number of passes associated with the recording mode is set. In step S404, recording is executed. Although two types of recording modes, the first recording mode and the second recording mode, are shown in the figure, there may be three or more.

[0205] In the case of this example, the recording apparatus can vary the number of recording passes (the number of times of performing main scanning on the same recording area of the recording medium) according to the recording mode, and can perform various recordings which is preferable.

[0206] According to the inkjet recording apparatus exemplified above, the recording method of the present embodiment can be preferably applied.

[0207] 4. Examples Hereinafter, the present invention will be described more specifically by way of examples, but the present invention is not limited to these examples. Hereinafter, “%” is based on mass unless otherwise specified.

[0208] 4.1. Preparation of Pigment Dispersion A 50 g of methyl ethyl ketone (MEK) was added to a flask equipped with a dropping funnel, a nitrogen inlet tube, a reflux condenser, a thermometer, and a stirring device, and the mixture was heated to 75 °C while bubbling nitrogen through it. A mixture of 80 g of butyl methacrylate, 50 g of methyl methacrylate, 15 g of styrene, 20 g of methacrylic acid, 50 g of MEK, and 500 mg of a polymerization initiator (azobisisobutyronitrile: AIBN) was added dropwise from the dropping funnel over 3 hours. After the addition, the mixture was heated under reflux for an additional 6 hours, cooled, and the amount of MEK that had evaporated was added back to obtain a resin solution (resin solid content 50 mass%, acid value 79 mg / KOH, Tg 65 °C). A predetermined amount of 20 mass% aqueous ammonia was added to 20 g of the solution as a neutralizing agent to neutralize the salt-forming groups 100%, and 50 g of a pigment (C.I. Pigment Blue 15:3) was added little by little while stirring, followed by kneading with a bead mill for 2 hours. 200 g of ion-exchanged water was added to the obtained kneaded product, stirred, and then heated under reduced pressure to distill off the MEK. Further, the concentration was adjusted with ion-exchanged water to obtain a pigment dispersion (pigment solid content 20 mass%, resin solid content 5 mass%).

[0209] 4.2. Preparation of Water-Dispersible Resin Into a reaction vessel equipped with a stirrer, a reflux condenser, a dropping funnel, and a thermometer, 2600 g of ion-exchanged water and 0.5 g of sodium lauryl sulfate were charged, and the temperature was raised to 70 °C while purging with nitrogen under stirring. The internal temperature was maintained at 70 °C, 4 g of potassium persulfate was added as a polymerization initiator, and after dissolution, an emulsion prepared by adding 2 g of acrylamide, 180 g of methyl methacrylate, 25 g of butyl acrylate, and 2 g of methacrylic acid to 300 g of ion-exchanged water and 0.5 g of sodium lauryl sulfate in advance under stirring was continuously added dropwise into the reaction solution over 3 hours. After completion of the dropping, aging was carried out for 1 hour. After completion of the aging, an emulsion prepared by adding 30 g of acrylamide, 1200 g of styrene, 200 g of 2-ethylhexyl methacrylate, and 30 g of methacrylic acid to 500 g of ion-exchanged water and 1.5 g of sodium lauryl sulfate in advance under stirring was continuously added dropwise into the reaction solution over 4 hours. After completion of the dropping, aging was carried out for 3 hours. The obtained aqueous emulsion was cooled to room temperature, and then ion-exchanged water and aqueous sodium hydroxide were added to adjust the solid content to 30% by weight and the pH to 8. In this way, a water-dispersible resin (resin A) having no crosslinking was produced. Furthermore, by adjusting the monomer ratio, water-dispersible resins (resin B) and water-dispersible resins (resin C) were also prepared in the same manner. In the preparation of resin B and resin C, the amount of methacrylic acid was increased and other monomers were decreased in an equal ratio without changing the total amount.

[0210] 4.3. Preparation of Ink Composition Each component was put into a container so as to have the compositions shown in Table 1 and Table 2, mixed and stirred with a magnetic stirrer for 2 hours, and then filtered through a membrane filter with a pore size of 5 μm to obtain ink compositions (Inks 1 to 23) according to Examples and Comparative Examples.

[0211]

Table 1

[0212]

Table 2

[0213] The abbreviations etc. in Tables 1 and 2 are as follows. · Pigment: C.I. Pigment Blue 15:3 · Pigment dispersant: Refer to the above “2.1. Preparation of Pigment Dispersion A” · Pigment dispersion: Pigment dispersion B “CAB-O-JET450C” self-dispersing pigment dispersion, manufactured by Cabot Corporation · Resin A (acid value 15): Refer to the above “2.2. Preparation of Water-dispersible Resin”, Tg 90°C, cohesiveness “C” · Resin B (acid value 30): Refer to the above “2.2. Preparation of Water-dispersible Resin”, Tg 90°C, cohesiveness “C” · Resin C (acid value 45): Refer to the above “2.2. Preparation of Water-dispersible Resin”, Tg 90°C, cohesiveness “B” · Hi-Tech E-6500: Wax emulsion; nonionic polyethylene wax, manufactured by Toho Chemical Industry Co., Ltd., cohesiveness “C”

[0214] Regarding the following abbreviations, they are described in the order of weight average molecular weight; neutralizing salt; structure; manufacturer; cohesiveness. · XIRAN2625H: 9000; ammonia; styrene maleic anhydride half ester resin; manufactured by Polyscope Co., Ltd.; A · XIRAN3000H: 10000; ammonia; styrene maleic anhydride resin; manufactured by Polyscope Co., Ltd.; B · XIRAN3000HNa: 10000; sodium hydroxide; styrene maleic anhydride half ester resin; manufactured by Polyscope Co., Ltd.; A · SN Dispersant 5027: 18000; ammonia; styrene maleic anhydride half ester resin; manufactured by Sannopco Ltd.; A · Polymeron 1318: 50000; ammonia; styrene maleic anhydride half ester resin; manufactured by Arakawa Chemical Industries, Ltd.; (Co., Ltd.); A · Joncryl HPD196: 9200; ammonia; styrene acrylic resin; manufactured by BASF Japan Ltd.; C

[0215] The weight-average molecular weight was measured using a high-speed GPC apparatus ("HLC-8220GPC" manufactured by Tosoh Corporation). Polystyrene was used as the standard substance, and tetrahydrofuran (THF) was used as the mobile phase.

[0216] Coagulability was evaluated by visually observing the state when an aqueous solution of 5% by mass of calcium propionate was mixed and stirred with an aqueous solution of 1% by mass of the resin solid content (aqueous dispersion) so that the mass ratio of resin solid content:calcium propionate was 2:1, and then allowed to stand for 5 minutes. The evaluation criteria are as follows. A: Precipitation occurs (high reactivity) B: Colloidal state (reactivity present) C: No aggregates, uniform state (no reactivity. No change from before mixing.)

[0217] · Surfynol DF110D: Antifoaming agent, acetylene diol-based surfactant, manufactured by Nissin Chemical Industry Co., Ltd. · BYK333: Surfactant, silicone-based surfactant, manufactured by BYK-Chemie Japan Co., Ltd.

[0218] Regarding the following abbreviations, they are described in the order of name; standard boiling point; melting point; physical properties; classification. · PG: Propylene glycol; 188°C; -59°C; liquid; diols · 1,2HD: 1,2-Hexanediol; 224°C; 2°C; liquid; diols · CPL: ε-Caprolactam; 267°C; 70°C; solid; nitrogen-containing solvent (cyclic amides) · 2P: 2-Pyrrolidone; 245°C; 25°C; liquid; nitrogen-containing solvent (cyclic amides) · DMPA: 3-Methoxy-N,N-dimethylpropanamide; 215°C; -49°C; liquid; nitrogen-containing solvent (chain amides) · DMSO: Dimethyl sulfoxide; 189°C; 19°C; liquid; sulfur-containing solvent · EXOM: 3-Ethyl-3-oxetanemethanol; 220°C; -31°C; liquid; cyclic ethers · TIPA: Triisopropanolamine; 301°C; 45°C; solid; amines

[0219] 4.4. Preparation of Treatment Liquid Put each component into a container so as to have the composition shown in Table 3, mix and stir with a magnetic stirrer for 2 hours, and then filter with a membrane filter having a pore diameter of 5 μm to obtain treatment liquids (treatment liquids 1 to 5) according to Examples and Comparative Examples. In the table, the pigment dispersion is the solid content of the pigment, and the resin is the solid content of the resin.

[0220]

Table 3

[0221] The abbreviations and the like in Table 3 are as follows. · Cation Master PD-30: Flocculant: Cationic resin (amine·epichlorohydrin co polymer), manufactured by Yokkaichi Synthetic Co., Ltd.

[0222] For the following abbreviations, they are described in the order of name; standard boiling point; melting point; property; classification. · PG: Propylene glycol; 188°C; -59°C; liquid; diols · 1,2HD: 1,2-hexanediol; 224°C; 2°C; liquid; diols · CPL: ε-caprolactam; 267°C; 70°C; solid; nitrogen-containing solvent (cyclic amides) · 2P: 2-pyrrolidone; 245°C; 25°C; liquid; nitrogen-containing solvent (cyclic amides)

[0223] · Surfynol DF110D: Defoaming agent, acetylene diol-based surfactant, manufactured by Nissin Chemical Industry Co., Ltd. · BYK333: Surfactant, silicone-based surfactant, manufactured by BYK-Chemie Japan Co., Ltd.

[0224] 4.5. Evaluation Method 4.5.1. Storage Stability of Ink Composition Seal 30 g of each prepared ink composition in an aluminum pack so that no air bubbles are mixed in, and leave it in a constant temperature bath at 60°C for 6 days. After taking it out and allowing it to cool naturally, use a rheometer (MCR702 / Anton Paar) to measure the shear rate at 200 s-1 The viscosity was measured, the thickening rate was calculated by comparing with the initial viscosity (right after ink formulation), and it was evaluated according to the following criteria. The results are shown in Tables 1 and 2. AA: Thickening rate less than 1% A: Thickening rate of 1% or more and less than 3% B: Thickening rate of 3% or more and less than 5% C: Thickening rate of 5% or more

[0225] 4.5.2. Test conditions As a recording device, a modified SC-R5050 (manufactured by Seiko Epson Corporation) was used, with a resolution of 1200×1200 dpi and an ink composition adhesion amount of 16 mg / inch 2 , and the treatment liquid adhesion amount was as described in Table 4. A solid pattern (cyan single color) was recorded. The recording medium was Orejet3165G-010 (vinyl chloride film, manufactured by Orafol Japan Co., Ltd.), and the recording was performed 9 times. The surface temperature of the recording medium on the platen was adjusted with a platen heater to be as described in Table 4 (primary heating), and the secondary heating temperature was 90°C to obtain the recorded matter for each example.

[0226] 4.5.3. Image quality (aggregation unevenness) Under the above test conditions, a solid pattern was printed under the printing conditions in Table 4, and the printed matter was visually observed. It was evaluated according to the following criteria, and the results are shown in Table 4. AA: No aggregation unevenness A: There is aggregation unevenness, but it is not noticeable B: The aggregation unevenness is noticeable but acceptable C: The aggregation unevenness is noticeable

[0227] 4.5.4. Rub resistance Under the above test conditions, after printing a solid pattern on the recording medium under the printing conditions in Table 4, it was left at room temperature for 30 minutes. The solid pattern printed area was cut into a 30×150 mm rectangle, and the degree of ink peeling when rubbed 100 times with a Kagaku-shi type rub tester (load 500 g) using a plain woven cloth was visually evaluated. It was evaluated according to the following criteria, and the results are shown in Table 4. AA: No peeling A: There is peeling of less than 20% of the evaluated area B: There is peeling of 20% or more but less than 40% of the evaluation area C: There is peeling of 40% or more but less than 50% of the evaluation area D: There is peeling of 50% or more of the evaluation area

[0228] 4.5.5. Clogging recovery (ink composition) A recording device under the above test conditions was prepared. However, non - ejection was intentionally caused in the nozzles of the ink head. In this state, with the printing conditions in Table 4, the ink was not ejected from the head and the device was run idle for 3 hours. After the idle run, cleaning was performed 3 times, and finally, it was determined how many nozzles were clogged. One cleaning discharged 1 g of ink from the nozzle row. The non - ejection of the nozzles was caused by tapping the nozzle surface with a wet benkot. The nozzle row consists of 400 nozzles. The results were recorded in Table 4 according to the following criteria. AA: No nozzle non - ejection A: Nozzle non - ejection is less than 3% B: Nozzle non - ejection is 3% or more but less than 5% C: Nozzle non - ejection is 5% or more

[0229] 4.5.6. Landing deviation (treatment liquid) and landing deviation (ink composition) A recording device under the above test conditions was prepared. Immediately after flushing with ink and treatment liquid respectively, a nozzle check pattern was recorded. With the printing conditions in Table 4, the treatment liquid and ink were not ejected and the device was run idle for 1 minute. After the idle run, the same nozzle check pattern was recorded. The average value for all nozzles for each of the ink and treatment liquid was used. However, non - ejection nozzles were excluded. The results were recorded in Table 4 according to the following criteria. AA: No difference in the landing position before and after the idle run A: There is a deviation within half of the nozzle distance B: There is a deviation within the nozzle distance C: There is a deviation exceeding the nozzle distance

[0230]

Table 4

[0231] 4.6. Evaluation Results In the ink sets of each example, which are ink sets comprising a treatment liquid containing a flocculant, a pigment dispersed with a pigment dispersant or a self-dispersing pigment, a water-dispersible resin, and a maleic acid resin which is a water-soluble resin, it was found that both image quality and rub resistance can be achieved.

[0232] On the other hand, in all of the comparative examples which are not like this, either the image quality or the rub resistance was inferior. Comparative Example 1 , 2 did not contain the maleic acid resin which is a water-soluble resin in the ink, and the image quality was inferior. Comparative Example 3 did not contain the water-dispersible resin in the ink, and the rub resistance was inferior.

[0233] The above-described embodiments and modified examples are merely examples and are not limited thereto. For example, it is also possible to appropriately combine each embodiment and each modified example.

[0234] The present invention includes a configuration substantially the same as the configuration described in the embodiments, for example, a configuration having the same functions, methods, and results, or a configuration having the same objectives and effects. Further, the present invention includes a configuration in which a non-essential part of the configuration described in the embodiments is replaced. Further, the present invention includes a configuration having the same operational effects as the configuration described in the embodiments or a configuration capable of achieving the same objective. Further, the present invention includes a configuration in which a known technique is added to the configuration described in the embodiments.

[0235] The following content is derived from the above-described embodiments and modified examples.

[0236] An ink set is an ink set comprising a treatment liquid containing a flocculant and an ink composition, wherein the ink composition is an aqueous ink containing a pigment dispersed with a pigment dispersant or a self-dispersing pigment, a water-dispersible resin, and a maleic acid resin which is a water-soluble resin.

[0237] According to this ink set, since the maleic acid resin in the ink composition is liable to be affected by the aggregating agent in the treatment liquid, when forming an image by bringing the treatment liquid into contact with the ink composition, aggregation unevenness hardly occurs in the image, and a high-quality image can be formed. Further, since the ink composition contains a water-dispersible resin, it is possible to suppress a decrease in the rubbing resistance of the image caused by the water solubility of the maleic acid resin, and the rubbing resistance of the image can be further improved by the synergistic effect of the maleic acid resin and the water-dispersible resin.

[0238] In the above ink set, The content of the maleic acid resin may be 0.1% by mass or more and 1.5% by mass or less with respect to the total amount of the ink composition.

[0239] According to this ink set, the effect of the aggregating agent in the treatment liquid can be obtained more remarkably, and a higher-quality image can be formed.

[0240] In the above ink set, The ratio (B / A) of the content (B) of the maleic acid resin to the content (A) of the water-dispersible resin in the ink composition may be 0.15 or less.

[0241] According to this ink set, the rubbing resistance of the formed image can be further improved.

[0242] In the above ink set, The maleic acid resin may have aggregability when mixed with an aqueous calcium propionate solution.

[0243] According to this ink set, the image quality of the formed image can be further improved.

[0244] In the above ink set, The water-dispersible resin may not have aggregability when mixed with an aqueous calcium propionate solution.

[0245] According to this ink set, even if a water-dispersible resin having no aggregability is used, the aggregability of the maleic acid-based resin can cause aggregation of the water-dispersible resin, so that an image with sufficient abrasion resistance can be obtained.

[0246] In the above ink set, The total amount of the water-dispersible resin and the maleic acid-based resin contained in the ink composition may be 0.2% by mass or more and 2% by mass or less based on the total amount of the ink composition.

[0247] According to this ink set, the effect of suppressing aggregation unevenness of the image and the effect of enhancing the abrasion resistance of the image can be obtained more remarkably.

[0248] In the above ink set, The maleic acid-based resin may have a carboxyl group.

[0249] According to this ink set, since the aggregability of the maleic acid-based resin becomes better, the image quality of the obtained image can be further improved. Further, according to this ink set, since the dissolution of the maleic acid-based resin becomes more stable, the storage stability of the ink composition is better.

[0250] In the above ink set, The carboxyl group may be partially or completely neutralized with ammonia, alkanolamine or alkylamine.

[0251] According to this ink set, since the dissolution of the maleic acid-based resin becomes more stable, the storage stability of the ink composition is better.

[0252] In the above ink set, The weight average molecular weight of the maleic acid-based resin may be 5000 or more and 60000 or less.

[0253] According to this ink set, the suppression of aggregation unevenness of the obtained image and the improvement of abrasion resistance can be further improved.

[0254] In the above ink set, The maleic acid-based resin may have a carboxyl group and an esterified carboxyl group.

[0255] According to this ink set, the balance between the hydrophilicity and hydrophobicity of the maleic acid-based resin becomes better, the storage stability of the ink composition becomes better, and the water resistance of the obtained image can be improved.

[0256] In the above ink set, The ink composition contains a pigment dispersed by the pigment dispersant, The pigment dispersant may be made of an acrylic resin.

[0257] According to this ink set, the dispersibility of the pigment in the ink composition can be made better.

[0258] In the above ink set, The water-dispersible resin is any one of an acrylic resin, a urethane resin, and a polyolefin resin, and may be contained in an amount of 1% by mass or more and 15% by mass or less based on the total amount of the ink composition. According to this ink set, the rub resistance of the obtained image can be further improved.

[0259] According to this ink set, the water retention of the ink composition can be further enhanced, and the clogging recovery property of the nozzles of the recording head can be further improved.

[0260] In the above ink set, The ink composition may contain polyols having a standard boiling point of 150°C or higher and 250°C or lower as water-soluble low-molecular organic compounds.

[0261] According to this ink set, the water retention of the ink composition can be further enhanced, and the clogging recovery property of the nozzles of the recording head can be further improved.

[0262] In the above ink set, The ink composition may contain, as a water-soluble low-molecular organic compound, any one of amides, sulfur-containing solvents, and cyclic ethers having a standard boiling point of 150°C or higher and 300°C or lower.

[0263] According to this ink set, since the water-soluble low-molecular organic compound easily functions as a dissolution aid for the water-dispersible resin, the particles of the water-dispersible resin are likely to swell and / or soften. As a result, the flatness of the surface of the formed image is further improved, and the rub resistance of the image can be further enhanced.

[0264] In the above ink set, The content of the water-soluble low-molecular organic compound contained in the ink composition may be 10% by mass or more and 30% by mass or less with respect to the total amount of the ink composition.

[0265] According to this ink set, the flatness of the surface of the formed image is further improved, and the rub resistance of the image can be further enhanced.

[0266] The recording method is using any of the above ink sets, an ink adhesion step of attaching the ink composition to a recording medium, and a treatment liquid adhesion step of attaching the treatment liquid to the recording medium.

[0267] According to this recording method, an image with high image quality and good rub resistance can be formed.

[0268] In the above recording method, the ink adhesion step is performed by an inkjet method, and the recording medium may be a low-absorbency recording medium or a non-absorbency recording medium.

[0269] According to this recording method, even on a low-absorbency recording medium or a non-absorbency recording medium where aggregation unevenness is relatively likely to occur, an image with high image quality and good rub resistance can be formed.

[0270] In the above recording method, A primary heating step of heating the ink composition attached to the recording medium may be provided.

[0271] According to this recording method, an image with high image quality and good rub resistance can be obtained, and the effect of high recording speed can be obtained more remarkably.

Explanation of reference numerals

[0272] 1... Inkjet recording apparatus, 2... Inkjet head, 2a... Nozzle surface, 3... IR heater, 4... Platen heater, 5... Heating heater, 6... Cooling fan, 7... Pre-heater, 8... Ventilation fan, 9... Carriage, 11... Platen, 12... Cartridge, 13... Carriage movement mechanism, 14... Conveying means, 101... Interface section, 102... CPU, 103... Memory, 104... Unit control circuit, 111... Conveying unit, 112... Carriage unit, 113... Head unit, 114... Drying unit, 121... Detector group, 130... Computer, CONT... Control section, MS... Main scanning direction, SS... Sub-scanning direction, M... Recording medium

Claims

1. An ink set comprising a treatment liquid containing a flocculant and an ink composition, wherein the ink composition is an aqueous ink containing a pigment dispersed by a pigment dispersant or a self-dispersing pigment, a water-dispersible resin, and a maleic acid resin which is a water-soluble resin, the maleic acid resin has no polymerizable carbon-carbon double bond, the content of the maleic acid resin is 0.05 to 0.8% by mass based on the total amount of the ink composition, the maleic acid resin is dissolved in water which is a solvent component contained in the ink composition, and when the ink composition contains a pigment dispersed by the pigment dispersant, it is contained separately in the ink composition from the pigment dispersant, the ink composition is an ink set that is not cured by irradiating with ultraviolet rays.

2. An ink set comprising a treatment liquid containing a flocculant and an ink composition, wherein the ink composition is an aqueous ink containing a pigment dispersed by a pigment dispersant or a self-dispersing pigment, a water-dispersible resin, and a maleic acid resin which is a water-soluble resin, the maleic acid resin has a carboxyl group, the carboxyl group is partially or completely neutralized with ammonia, alkanolamine or alkylamine, the maleic acid resin is dissolved in water which is a solvent component contained in the ink composition, and when the ink composition contains a pigment dispersed by the pigment dispersant, it is contained separately in the ink composition from the pigment dispersant.

3. In Claim 2, the content of the maleic acid resin is 0.1% by mass or more and 1.5% by mass or less based on the total amount of the ink composition.

4. In any one of Claims 1 to 3, the ratio (B / A) of the content (B) of the maleic acid resin to the content (A) of the water-dispersible resin in the ink composition is 0.15 or less.

5. In any one of Claims 1 to 4, the maleic acid resin has aggregability when mixed with an aqueous calcium propionate solution.

6. In any one of Claims 1 to 5, the water-dispersible resin has no aggregability when mixed with an aqueous calcium propionate solution.

7. In any one of Claims 1 to 6, ​ The total amount of the water-dispersible resin and the maleic acid resin contained in the ink composition is 0.2% by mass or more and 5% by mass or less based on the total amount of the ink composition, an ink set.

8. In any one of Claims 1 to 6, the content of the water-dispersible resin is 1 to 20% by mass based on the total amount of the ink composition, an ink set.

9. In any one of Claims 1 to 8, the weight average molecular weight of the maleic acid resin is 5,000 or more and 60,000 or less, an ink set.

10. In any one of Claims 1 to 9, the maleic acid resin has a carboxyl group and an esterified carboxyl group, an ink set.

11. In any one of Claims 1 to 10, the ink composition contains a pigment dispersed by the pigment dispersant, the pigment dispersant is made of an acrylic resin, an ink set.

12. In any one of Claims 1 to 11, the water-dispersible resin is any one of an acrylic resin, a urethane resin, and a polyolefin resin, and is contained in an amount of 1% by mass or more and 15% by mass or less based on the total amount of the ink composition, an ink set.

13. In any one of Claims 1 to 12, the ink composition contains polyols having a standard boiling point of 150°C or higher and 250°C or lower as a water-soluble low-molecular organic compound, an ink set.

14. In any one of Claims 1 to 13, the ink composition contains any one of amides, sulfur-containing solvents, and cyclic ethers having a standard boiling point of 150°C or higher and 300°C or lower as a water-soluble low-molecular organic compound, an ink set.

15. In Claim 13 or Claim 14, the content of the water-soluble low-molecular organic compound contained in the ink composition is 10% by mass or more and 30% by mass or less based on the total amount of the ink composition, an ink set.

16. Using the ink set according to any one of Claims 1 to 15, an ink adhesion step of adhering the ink composition to a recording medium, a treatment liquid adhesion step of adhering the treatment liquid to the recording medium, a recording method.

17. In Claim 16, the ink adhesion step is performed by an inkjet method, the recording medium is a low-absorbency recording medium or a non-absorbency recording medium, a recording method.

18. In claim 16 or claim 17, A recording method comprising a primary heating step of heating the ink composition adhered to the recording medium.

Images