Water-based ink for inkjet recording, ink set, inkjet recording device, and image forming method.

Abstract

We provide technology that can achieve high frictional resistance. [Solution] An aqueous inkjet recording ink is used to form an image on a fabric material. The aqueous inkjet recording ink comprises a pigment, a binder, a crosslinking agent, and wax particles. The binder contains a urethane resin. The crosslinking agent contains a blocked isocyanate compound. The melting point of the wax particles is between 90°C and 140°C.

Description

Technical Field

[0001] The present specification discloses techniques relating to water-based inks for inkjet recording, ink sets, inkjet recording apparatuses, and image forming methods. In particular, the present specification discloses techniques relating to water-based inks and the like that can be used for textile printing on fabric materials.

Background Art

[0002] Patent Document 1 discloses a water-based ink for inkjet recording that is used for textile printing on fabrics. This water-based ink contains a pigment, a water-dispersible resin, and a crosslinking agent.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problem to be Solved by the Invention

[0004] The present specification provides a technique capable of achieving high rub fastness.

Means for Solving the Problem

[0005] The water-based ink for inkjet recording disclosed in the present specification is used for forming an image on a fabric material. The water-based ink for inkjet recording includes a pigment, a binder, a crosslinking agent, and wax particles. The binder contains a urethane-based resin. The crosslinking agent contains a blocked isocyanate compound. The melting point of the wax particles is 90°C or higher and 140°C or lower.

[0006] In the ink described above, some of the wax particles present in the resin coating are distributed to cover the surface of the resin coating, which is thought to improve the friction fastness of the resin coating. On the other hand, if the wax particles melt during the heat treatment to form the resin coating, there is a risk that they will inhibit the crosslinking reaction between the binders by the crosslinking agent. However, the melting point of the wax particles described above is relatively high, between 90°C and 140°C. Therefore, the timing at which the wax particles begin to melt during the heat treatment to form the resin coating can be delayed. Consequently, in the ink described above, the wax particles begin to melt after the crosslinking reaction has progressed to a certain extent. This suppresses the inhibition of the crosslinking reaction by the wax particles and prevents a decrease in the strength of the coating. As a result, high friction fastness can be achieved.

[0007] The ink set is also novel and useful. The ink set comprises the above-mentioned water-based inkjet recording ink and a pretreatment liquid. The pretreatment liquid is applied to the fabric material before forming an image on the fabric material using the water-based inkjet recording ink.

[0008] A novel and useful inkjet recording device is also provided. The inkjet recording device comprises an ink storage section, an ink ejection section, and an aqueous inkjet recording ink stored in the ink storage section. The inkjet recording device ejects the aqueous inkjet recording ink from the ink ejection section to form an image on a fabric material. The aqueous inkjet recording ink comprises a pigment, a binder, a crosslinking agent, and wax particles. The binder contains a urethane resin. The crosslinking agent contains a blocked isocyanate compound. The melting point of the wax particles is 90°C to 140°C.

[0009] A novel and useful image forming method is also available, which involves forming an image on a fabric material using an inkjet recording method. This image forming method comprises an image forming step and a drying step. In the image forming step, an image is formed on the fabric material using the water-based inkjet recording ink. In the drying step, the water-based inkjet recording ink is dried by heating the fabric material on which the image has been formed. The water-based inkjet recording ink comprises a pigment, a binder, a crosslinking agent, and wax particles. The binder contains a urethane resin. The crosslinking agent contains a blocked isocyanate compound. The melting point of the wax particles is 90°C or higher and 140°C or lower. [Brief explanation of the drawing]

[0010] [Figure 1] This shows the configuration of an inkjet recording device. [Figure 2] This shows a schematic configuration of the discharge head mounted on the carriage. [Figure 3] This shows an example of a configuration in which a pretreatment solution is applied before image formation by an inkjet recording device. [Modes for carrying out the invention]

[0011] (Water-based ink for inkjet recording) Hereinafter, an embodiment of the water-based inkjet recording ink disclosed herein will be described. Hereinafter, the water-based inkjet recording ink may be simply referred to as water-based ink. The water-based ink is used to form an image on a fabric material. Examples of fabric materials include woven fabrics, nonwoven fabrics, knitted fabrics, etc., composed of fiber materials. Examples of fiber materials include natural fibers and synthetic fibers. Examples of natural fibers include cotton, linen, wool, silk, etc. Examples of synthetic fibers include rayon, vinylon, nylon, acrylic, polyurethane, polyester, or acetate, etc. The fabric material may be a blended woven fabric or blended nonwoven fabric using two or more types selected from these. The water-based ink comprises a pigment, a binder, a crosslinking agent, and wax particles.

[0012] (Pigment) The pigments are not particularly limited and include, for example, carbon black, inorganic pigments, and organic pigments. Examples of carbon black include furnace black, lamp black, acetylene black, and channel black. Examples of inorganic pigments include titanium dioxide, iron oxide-based inorganic pigments, and carbon black-based inorganic pigments. Examples of organic pigments include azo pigments such as azo lakes, insoluble azo pigments, condensed azo pigments, and chelate azo pigments; polycyclic pigments such as phthalocyanine pigments, perylene and perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, thioindigo pigments, isoindolinone pigments, and quinophthalone pigments; dye lake pigments such as basic dye-type lake pigments and acid dye-type lake pigments; nitro pigments: nitroso pigments; aniline black daylight fluorescent pigment; and others. In addition, other pigments can be used as long as they are dispersible in the aqueous phase. Specific examples of these pigments include, for example, CI Pigment Black 1, 6 and 7; CI Pigment Yellow 1, 2, 3, 12, 13, 14, 15, 16, 17, 55, 74, 78, 150, 151, 154, 155, 180, 185 and 194; CI Pigment Orange 31 and 43; CI Pigment Red 2, 3, 5, 6, 7, 12, 15, 16, 48, 48:1, 53:1, 57, 57:1, 112, 122, 123 Examples include 139, 144, 146, 149, 150, 166, 168, 175, 176, 177, 178, 184, 185, 190, 202, 209, 221, 222, 224 and 238; CI Pigment Violet 19 and 196; CI Pigment Blue 1, 2, 3, 15, 15:1, 15:2, 15:3, 15:4, 16, 22 and 60; CI Pigment Green 7 and 36; and solid solutions of these pigments. Water-based inks may be prepared by dispersing pigments in water with a dispersant. As the dispersant, for example, a general polymer dispersant may be used, or it may be prepared in-house. Polymer dispersants include pigment dispersion resins and resin dispersants. In addition, in water-based inks, the pigments may be encapsulated by polymers.

[0013] One method for dispersing pigments using pigment dispersion resins is to disperse the pigments using a dispersion apparatus. The dispersion apparatus used for dispersing pigments is not particularly limited as long as it is a general-purpose disperser, but examples include ball mills, roll mills, and sand mills.

[0014] The pigment may be a self-dispersing pigment. A self-dispersing pigment is one in which, for example, at least one of a hydrophilic functional group such as a carbonyl group, hydroxyl group, carboxylic acid group, sulfonic acid group, or phosphate group, or a salt thereof, is introduced into the pigment particles by chemical bonding, either directly or via other groups, so that it can be dispersed in water without the use of a dispersant.

[0015] Pigments may be used individually or in combination of two or more types. The pigment solid content relative to the total amount of aqueous ink (pigment solid content) is not particularly limited and can be appropriately determined based on the desired optical density or saturation. The range of pigment solid content is, for example, 0.10% to 20.00% by mass, 0.50% to 15.00% by mass, 1.00% to 10.00% by mass, and 2.00% to 8.00% by mass. The pigment solid content is the mass of the pigment only and does not include the mass of resin dispersants, etc. In other words, the pigment solid content is calculated on an effective ingredient basis.

[0016] (binder) The binder is formulated to improve the fixation and friction fastness of the pigment to the fabric by forming a resin coating on the fabric. The binder may be formulated, for example, in the form of an emulsion in an aqueous ink, or dispersed in the aqueous ink in the form of resin particles. The binder contains a urethane resin. The urethane resin may be anionic, nonionic, or cationic.

[0017] Urethane resins are resins that have urethane bonds in their molecules. The urethane bonds may be present in the main chain or in the side chains. Examples of urethane resins include polyester-type polyurethane resins, polyether-type polyurethane resins, polyether ester-type polyurethane resins, and polycarbonate-type polyurethane resins. Polyurethane resins are obtained, for example, by reacting a polyisocyanate component with one or more polyol components, which are polyester-type, polylactone-type, polycarbonate-type, and polyether-polycarbonate-type, and a chain extender, chain arrester, etc., as needed, using a urethane catalyst as needed, in a known manner.

[0018] Polyisocyanates are compounds or derivatives thereof having two or more isocyanate groups. Examples of polyisocyanates include diisocyanates and triisocyanates. Other examples of polyisocyanates include one or more selected from aliphatic polyisocyanates, alicyclic polyisocyanates, aromatic polyisocyanates, aromatic aliphatic polyisocyanates, and aromatic alicyclic polyisocyanates. Polyisocyanates may have isocyanate groups protected with a blocking agent. Examples of polyisocyanate derivatives include polymers and modified products (adducts, carbodiimides, allophanates, uretdiones, isocyanurates, biuretides, uretoimines, dimers, trimers, pentamers, heptamers, etc.).

[0019] Examples of polyols include aromatic polyols, aliphatic polyols, and alicyclic polyols. Polyols may be either saturated or unsaturated. Polyols only need to have two or more hydroxyl groups; examples include diols and triols.

[0020] As the urethane-based resin, a commercially available product may be used. Examples of commercially available products include "TAKELAC (registered trademark) W-5030", "TAKELAC W-5130 (glass transition temperature: 26°C)", "TAKELAC W-5661", "TAKELAC W-6010", "TAKELAC W-6020", "TAKELAC W-6061 (glass transition temperature: -20°C)", "TAKELAC W-6110 (glass transition temperature: 25°C)", "TAKELAC WS-6021" manufactured by Mitsui Chemicals, Inc., "SUPERFLEX (registered trademark) 126", "SUPERFLEX 150 (glass transition temperature: 40°C)", "SUPERFLEX 150HS (glass transition temperature: 32°C)", "SUPERFLEX 170 (glass transition temperature: 75°C)", "SUPERFLEX 210 (glass transition temperature: 41°C)", "SUPERFLEX 300 (glass transition temperature: -42°C)", "SUPERFLEX 500M (glass transition temperature: -39°C)", "SUPERFLEX 620 (glass transition temperature: 43°C)", "SUPERFLEX 740 (glass transition temperature: -34°C)", "SUPERFLEX 820 (glass transition temperature: 46°C)", "SUPERFLEX 830HS (glass transition temperature: 68°C)", "SUPERFLEX 860 (glass transition temperature: 36°C)", "SUPERFLEX E-2000 (glass transition temperature: -38°C)" manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., "Impranil DLP-R", "Impranil DLN-W50", "Impranil DLP1380" manufactured by Sumika Covestro Urethane Co., Ltd., and the like. One type of these binders may be used alone, or two or more types may be used in combination.

[0021] The content of the binder relative to the total amount of the aqueous ink is not particularly limited. The lower limit of the content, in terms of solid content, is, for example, 1.00 mass% or more, 2.00 mass% or more, 2.50 mass% or more, 3.00 mass% or more, or 3.50 mass% or more. The upper limit of the content, in terms of solid content, is, for example, 15.00 mass% or less, 10.00 mass% or less, 9.00 mass% or less, 8.00 mass% or less, or 7.00 mass% or less. The range of the content can be set by appropriately combining the above upper and lower limits. The range of the content, in terms of solid content, is, for example, 1.00 mass% to 15.00 mass%, 2.00 mass% to 10.00 mass%, 2.50 mass% to 9.00 mass%, 3.00 mass% to 8.00 mass%, or 3.50 mass% to 7.00 mass%. When the content of the binder is within the above range, the pigment can be favorably fixed to the fabric material, and high rub fastness of the resin coating film can be ensured.

[0022] The glass transition temperature of the urethane-based resin is not particularly limited. The lower limit of the glass transition temperature is, for example, -50°C or higher, -45°C or higher, -40°C or higher, or -35°C or higher. The upper limit of the glass transition temperature is, for example, 80°C or lower, 60°C or lower, 40°C or lower, or 30°C or lower. The range of the glass transition temperature can be set by appropriately combining the above upper and lower limits. The range of the glass transition temperature is, for example, -50°C to 80°C, -45°C to 60°C, -40°C to 40°C, or -35°C to 30°C.

[0023] The aqueous ink may further contain other water-dispersible resins in addition to the urethane-based resin as the binder. Examples of the water-dispersible resin include acrylic resins, polycarbonate-based resins, styrene-based resins, and polyester-based resins.

[0024] (Crosslinking agent) Crosslinking agents are added to the binder to impart crosslinking properties. Crosslinking agents include blocked isocyanate compounds. Blocked isocyanate compounds are obtained by reacting the active isocyanate groups in a polyisocyanate compound with a blocking agent to inactivate them. Blocked isocyanate compounds cannot undergo crosslinking reactions and are chemically stable. Therefore, inks containing blocked isocyanate compounds can have high storage stability. When a blocked isocyanate compound is heat-treated, the blocking agent bound to the isocyanate groups dissociates, forming active isocyanate groups and becoming capable of crosslinking reactions. Blocked isocyanate compounds may be anionic, nonionic, or cationic.

[0025] Examples of compounds constituting the polyisocyanate portion of a blocked isocyanate compound include polyisocyanate compounds or derivatives thereof having two or more isocyanate groups per molecule. Examples of compounds constituting the polyisocyanate portion of a blocked isocyanate compound include various polyisocyanate compounds such as diisocyanate compounds, triisocyanate compounds, tetraisocyanate compounds, pentaisocyanate compounds, and hexisocyanate compounds. Examples of polyisocyanate compounds include one or more selected from aliphatic polyisocyanate compounds, alicyclic polyisocyanate compounds, aromatic polyisocyanate compounds, aromatic aliphatic polyisocyanate compounds, and aromatic alicyclic polyisocyanate compounds. Examples of derivatives of the compounds constituting the polyisocyanate portion of the blocked isocyanate compound include dimers, trimers, and other polymers of the compounds constituting the polyisocyanate portion of the blocked isocyanate compound, as well as isocyanurates, allophanates, biuretes, and the like.

[0026] Examples of aliphatic polyisocyanate compounds include one or more selected from ethylene diisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, 1,6-hexamethylene diisocyanate (HDI), ethyl ethylene diisocyanate, heptamethylene diisocyanate, dodecamethylene diisocyanate, 1,6,11-undecane triisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, lysine diisocyanate (2,6-diisocyanatomethyl caproate), bis(2-isocyanatoethyl) fumarate, bis(2-isocyanatoethyl) carbonate, and 2-isocyanatoethyl-2,6-diisocyanatohexanoate.

[0027] Examples of alicyclic polyisocyanate compounds include one or more selected from isophorone diisocyanate (IPDI), 4,4'-dicyclohexylmethane diisocyanate (hydrogenated MDI), hydrogenated xylylene diisocyanate, hydrogenated toluene diisocyanate, cyclobutane diisocyanate, cyclopentane diisocyanate, 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, methylcyclohexylene diisocyanate, bis(2-isocyanatoethyl)-4-cyclohexene-1,2-dicarboxylate, 2,5-norbornane diisocyanate, 2,6-norbornane diisocyanate, and 2-heptyl-3,4-bis(9-isocyanatonol)-1-pentyl-cyclohexane.

[0028] Examples of aromatic polyisocyanate compounds include one or more selected from 2,4-tole diisocyanate, 2,6-tole diisocyanate, 4,4'-diphenylmethane diisocyanate, p-phenylenediisocyanate, m-phenylenediisocyanate, 1,5-naphthylene diisocyanate, 3,3'-dimethyldiphenyl-4,4'-diisocyanate, dianisidine diisocyanate, 4,4'-toluidine diisocyanate, 4,4'-diphenyl ether diisocyanate, triphenylmethane triisocyanate, 1,3,5-triisocyanatobenzene, 2,4,6-triisocyanatotoluene, dimethyltriphenylmethane tetraisocyanate, and one or more selected from polymethylene polyphenyl polyisocyanate (crude MDI, polymeric MDI) and crude tole diisocyanate (crude TDI).

[0029] Examples of aromatic aliphatic polyisocyanate compounds include one or more selected from 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, and tetramethylxylylene diisocyanate.

[0030] Examples of blocking agents include one or more selected from phenol, cresol, ethylphenol, butylphenol, 2-hydroxypyridine, dimethyl malonate, diethyl malonate, methyl acetoacetate, ethyl acetoacetate, acetylacetone, butyl mercaptan, dodecyl mercaptan, acetanilide, acetic acid amide, ε-caprolactam, δ-valerolactam, γ-butyrolactam, succinimide, maleimide, imidazole, 2-methylimidazole, urea, thiourea, ethyleneurea, formaldehyde oxime, acetaldehyde oxime, acetone oxime, methyl ethyl ketoxime, methyl isobutyl ketoxime, cyclohexanone oxime, carbazole, dimethylpyrazole, and triazole.

[0031] The dissociation temperature of the blocked isocyanate compound is not particularly limited. The lower limit of the dissociation temperature is, for example, 60°C or higher, 80°C or higher, 100°C or higher, 110°C or higher, or 120°C or higher. The upper limit of the dissociation temperature is, for example, 200°C or lower, 180°C or lower, 160°C or lower, 140°C or lower, or 130°C or lower. The range of the dissociation temperature can be set by appropriately combining the upper and lower limits mentioned above. The range of the dissociation temperature is, for example, 60°C to 200°C, 80°C to 180°C, 100°C to 160°C, 110°C to 140°C, or 120°C to 130°C. If the dissociation temperature of the blocked isocyanate compound is below the upper limit, the blocking agent can be suitably dissociated by heat treatment, and the crosslinking reaction can proceed. Furthermore, if the dissociation temperature of the blocked isocyanate compound is above the lower limit, the storage stability of the aqueous ink can be improved. Furthermore, from the viewpoint of initiating the crosslinking reaction after the formation of the resin coating by the binder has begun, it is preferable that the dissociation temperature is higher than the glass transition temperature of the urethane resin described above.

[0032] Commercially available blocked isocyanate compounds may be used. Examples of commercially available products include Baxenden's "Trixene® AquaBI210 (dissociation temperature: 120°C)" and "Trixene AquaBI220 (dissociation temperature: 120°C)"; and Meisei Chemical Industry Co., Ltd.'s "DM-6400 (dissociation temperature: 130°C)", "Meikanate® DM-3031CONC (dissociation temperature: 180°C)", "Meikanate DM-350Z (dissociation temperature: 180°C)", and "Meikanate TP-10 (dissociation temperature: 130°C)". Examples include "Meikanate CX (dissociation temperature: 120℃)", "SU-268A (dissociation temperature: 120℃)", "NBP-873D (dissociation temperature: 160℃)", "NBP-211 (dissociation temperature: 160℃)", "SU-315V (dissociation temperature: 100℃)"; and "Elastron (registered trademark) BN-69 (dissociation temperature: 120℃)", "Elastron BN-77 (dissociation temperature: 120℃)", and "Elastron BN-27 (dissociation temperature: 180℃)" manufactured by Daiichi Kogyo Seiyaku Co., Ltd. From the viewpoint of the reactivity of the crosslinking reaction, hexamethylene diisocyanate (HDI) is preferred as the compound constituting the polyisocyanate portion of the blocked isocyanate compound. That is, as the blocked isocyanate compound, "SU-268A", "SU-315V", "NBP-211", etc. are preferred.

[0033] The crosslinking agents described above may be used individually or in combination of two or more. The content of the crosslinking agents is adjusted as appropriate according to the content of the binder described above. The ratio of the crosslinking agent content to the binder content is not particularly limited. The lower limit of this ratio, in terms of solid content, is, for example, 0.01 or more, 0.05 or more, 0.10 or more, 0.15 or more, and 0.20 or more. The upper limit of this ratio, in terms of solid content, is, for example, 0.70 or less, 0.60 or less, 0.50 or less, 0.45 or less, and 0.40 or less. The range of this ratio can be set by appropriately combining the upper and lower limits described above. The range of this ratio, in terms of solid content, is, for example, 0.01 to 0.70, 0.05 to 0.60, 0.10 to 0.50, 0.15 to 0.45, and 0.20 to 0.40.

[0034] The amount of crosslinking agent relative to the total amount of water-based ink is not particularly limited. The lower limit of the amount is, for example, 0.30% by mass or more, 0.50% by mass or more, 0.60% by mass or more, 0.80% by mass or more, and 0.90% by mass or more, on a solid content basis. The upper limit of the amount is, for example, 10.00% by mass or less, 5.00% by mass or less, 4.00% by mass or less, 3.00% by mass or less, and 2.00% by mass or less, on a solid content basis. The range of the amount can be set by appropriately combining the upper and lower limits mentioned above. The range of the amount is, for example, 0.30% by mass or more and 10.00% by mass or less, 0.50% by mass or more and 5.00% by mass or less, 0.60% by mass or more and 4.00% by mass or less, 0.80% by mass or more and 3.00% by mass or less, and 0.90% by mass or more and 2.00% by mass or less, on a solid content basis.

[0035] Furthermore, in addition to the blocked isocyanate compound, the aqueous ink may also contain other crosslinking agents. Examples of other crosslinking agents include oxazoline group-containing compounds, carbodiimide compounds, aziridine group-containing compounds, epoxy group-containing compounds, and aqueous crosslinking agents in which hydrophilic segments are imparted to polycarbodiimide resins.

[0036] (wax particles) Wax particles are added to improve the color development of water-based inks and to improve the friction fastness of resin coatings. Wax particles contain wax. Examples of waxes include natural waxes and synthetic waxes. Wax particles may also contain components other than wax. However, from the viewpoint of improving friction fastness, the wax content in the wax particles is preferably, for example, 80.00% by mass or more and 100% by mass or less. It is more preferable that the wax particles consist only of wax.

[0037] Examples of natural waxes include petroleum-based waxes such as paraffin wax and microcrystalline wax; lignite-based waxes such as montane wax; plant-based waxes such as carnauba wax and candelilla wax; and animal and plant-based waxes such as beeswax and lanolin. Examples of synthetic waxes include polyethylene wax, polypropylene wax, oxidized polyethylene wax, polyalkylene wax, and oxidized polyalkylene wax. Among these, synthetic waxes are preferred, and polyethylene wax, oxidized polyethylene wax, and paraffin wax are particularly preferred. The wax particles may be, for example, a wax emulsion. A wax emulsion is composed of, for example, wax particles and a dispersion medium, in which the wax particles are dispersed in the dispersion medium with a specific particle size, rather than being dissolved.

[0038] Commercially available waxes may be used. Examples of commercially available waxes include BYK-Chemie's "CERAFLOUR(registered trademark) 925 (melting point: 115℃)", "CERAFLOUR929 (melting point: 115℃)", "CERAFLOUR950 (melting point: 135℃)", "CERAFLOUR991 (melting point: 115℃)", "AQUACER(registered trademark) 507 (melting point: 130℃)", and "AQUACER526 (melting point: 1 0.5℃)", "AQUACER537 (Melting point: 110℃)", "AQUACER1547 (Melting point: 125℃)", "AQUACER515 (Melting point: 130℃)", "AQUACER539 (Melting point: 90℃)", "AQUAMAT(registered trademark)208 (Melting point: 135℃)", "AQUAMAT263 (Melting point: 130℃)", "AQUAMAT272 (Melting point: 125℃)"; "MINE RPOL(registered trademark) 221 (melting point: 120℃), etc.; Mitsui Chemicals, Inc.'s "Chemipearl(registered trademark) W100 (melting point: 123℃)", "Chemipearl W200 (melting point: 108℃)", "Chemipearl W300 (melting point: 127℃)", "Chemipearl W400 (melting point: 108℃)", "Chemipearl W500 (melting point: 109℃)", "Chemipearl W700 (melting point: 127℃)", "Chemipearl Examples include "W800 (melting point: 126℃)", "Chemipearl W900 (melting point: 125℃)", and "Hi-Tec E-7100S (melting point: 140℃)", "Hi-Tec E-8237 (melting point: 106℃)", "Hi-Tec E-6314 (melting point: 137℃)", "Hi-Tec E-6700 (melting point: 140℃)", and "Hi-Tec E-8010 (melting point: 140℃)" manufactured by Toho Chemical Industry Co., Ltd.

[0039] From the viewpoint of suppressing the inhibition of the crosslinking reaction due to the melting of the wax particles, wax particles with a melting point of 90°C to 140°C are used. The lower limit of the melting point is, for example, 90°C or higher, 100°C or higher, 110°C or higher, 120°C or higher, 130°C or higher, and 135°C or higher. The upper limit of the melting point is, for example, 140°C or lower, 139°C or lower, and 138°C or lower. The range of the melting point can be set by appropriately combining the upper and lower limits mentioned above. The range of the melting point is, for example, 90°C to 140°C, 100°C to 139°C, 110°C to 138°C, 120°C to 140°C, 130°C to 140°C, and 135°C to 140°C. If the melting point of the wax particles is below the above upper limits, the dry friction fastness and wet friction fastness can be improved. Furthermore, if the melting point of the wax particles is above the lower limit mentioned above, it is easier to adjust the relationship between the melting point and the glass transition temperature of the binder. From the viewpoint of suppressing the inhibition of the crosslinking reaction by the wax particles, the melting point of the wax particles may be 5°C or more higher than the dissociation temperature of the blocked isocyanate compound. Also, from the viewpoint of further suppressing the inhibition of the crosslinking reaction by the wax particles, the melting point of the wax particles may be 15°C or more higher than the dissociation temperature of the blocked isocyanate compound.

[0040] Wax particles may be used individually or in combination of two or more types. The amount of wax particles relative to the total amount of water-based ink is not particularly limited. The lower limit of the content is, for example, 0.10% by mass or more, 0.20% by mass or more, 0.30% by mass or more, 0.40% by mass or more, and 0.50% by mass or more, on a solid content basis. The upper limit of the content is, for example, 5.00% by mass or less, 3.00% by mass or less, 2.00% by mass or less, 1.50% by mass or less, and 1.00% by mass or less, on a solid content basis. The range of the content can be set by appropriately combining the upper and lower limits mentioned above. The range of the content, calculated on a solid content basis, is, for example, 0.10% to 5.00% by mass, 0.20% to 3.00% by mass, 0.30% to 2.00% by mass, 0.40% to 1.50% by mass, and 0.50% to 1.00% by mass. If the wax particle content is within the above range, the lubricity of the resin coating surface can be improved, and the dry friction fastness can be improved.

[0041] (Other ingredients) Water-based inks may further contain water, water-soluble organic solvents, and surfactants as other components.

[0042] (water) The water is preferably deionized water or pure water. The water content relative to the total amount of water-based ink is appropriately determined according to the desired ink characteristics, etc. The range of water content is, for example, 15.00% by mass or more and 95.00% by mass or less, 35.00% by mass or more and 85.00% by mass or less, or 50.00% by mass or more and 80.00% by mass or less. The water content may, for example, be the remainder of the other components.

[0043] (Water-soluble organic solvent) Examples of water-soluble organic solvents include wetting agents and penetrating agents.

[0044] The wetting agents are not particularly limited and include, for example, lower alcohols such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, and tert-butyl alcohol; amides such as dimethylformamide and dimethylacetamide; ketones such as acetone; keto alcohols such as diacetone alcohol; ethers such as tetrahydrofuran and dioxane; polyethers such as polyalkylene glycol; polyhydric alcohols such as alkylene glycol, glycerin, trimethylolpropane, and trimethylolethane; 2-pyrrolidone; N-methyl-2-pyrrolidone; 1,3-dimethyl-2-imidazolidinone; and the like. Examples of polyalkylene glycols include polyethylene glycol and polypropylene glycol. Examples of alkylene glycols include ethylene glycol, propylene glycol, butylene glycol, diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, thiodiglycol, and hexylene glycol. These wetting agents may be used individually or in combination of two or more types. Among these, glycerin, polyethylene glycol, and the like are preferred.

[0045] A single type of wetting agent may be used alone, or two or more types may be used in combination. When a water-based ink contains a wetting agent, the amount of wetting agent relative to the total amount of water-based ink is not particularly limited. The range of the wetting agent is, for example, 1.00% by mass or more and 95.00% by mass or less, 5.00% by mass or more and 80.00% by mass or less, or 10.00% by mass or more and 50.00% by mass or less. When a water-based ink contains a wetting agent, if the wetting agent content is within the above range, drying of the ink during storage can be prevented, and the storage stability of the ink can be improved.

[0046] Examples of penetrating agents include glycol ethers. Examples of glycol ethers include ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol-n-propyl ether, diethylene glycol methyl ether, diethylene glycol ethyl ether, diethylene glycol-n-propyl ether, diethylene glycol-n-butyl ether, diethylene glycol-n-hexyl ether, triethylene glycol methyl ether, triethylene glycol ethyl ether, triethylene glycol-n-propyl ether, triethylene glycol-n-butyl ether, propylene glycol methyl ether, propylene glycol ethyl ether, propylene glycol-n-propyl ether, propylene glycol-n-butyl ether, dipropylene glycol methyl ether, dipropylene glycol ethyl ether, dipropylene glycol-n-propyl ether, dipropylene glycol-n-butyl ether, tripropylene glycol methyl ether, tripropylene glycol ethyl ether, tripropylene glycol-n-propyl ether, and tripropylene glycol-n-butyl ether. Among these, triethylene glycol-n-butyl ether is preferred.

[0047] Penetrants may be used individually or in combination of two or more types. When an aqueous ink contains a penetrant, the amount of penetrant relative to the total amount of aqueous ink is not particularly limited. The range of the content is, for example, 0.10% by mass or more and 20.00% by mass or less, 0.50% by mass or more and 10.00% by mass or less, and 1.00% by mass or more and 5.00% by mass or less.

[0048] (Surfactants) The surfactant is not particularly limited and can be appropriately selected depending on the purpose. Examples of surfactants include anionic surfactants, nonionic surfactants, cationic surfactants, amphoteric surfactants, silicone-based surfactants, and fluorine-based surfactants.

[0049] Examples of anionic surfactants include alkyl sulfocarboxylates, α-olefin sulfonates, polyoxyethylene alkyl ether acetates, polyoxyethylene alkyl ether sulfates, N-acyl amino acids or their salts, N-acyl methyl taurates, alkyl sulfates, polyoxyalkyl ether sulfates, alkyl sulfates, polyoxyethylene alkyl ether phosphates, rosinic acid soaps, castor oil sulfates, lauryl alcohol sulfates, alkylphenol type phosphates, alkyl type phosphates, alkylaryl sulfonates, diethyl sulfosaturates, diethylhexyl sulfosaturates, and dioctyl sulfosaturates.

[0050] Examples of nonionic surfactants include polyols, glycol ethers, polyoxyethylene alkyl ethers, polyoxyethylene alkyl esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene alkylphenyl ethers, polyoxyethylene alkylamines, polyoxyethylene alkylamides, and acetylene glycols. Commercially available nonionic surfactants may also be used. Examples of commercially available products include "Orphin® E1004," "Orphin E1008," and "Orphin E1010" from Nisshin Chemical Industry Co., Ltd.; "Surfinol® 440," "Surfinol 465," and "Surfinol 485" from Air Products and Chemicals; and "Acetylenel® E40" and "Acetylenel E100" from Kawaken Fine Chemical Co., Ltd.

[0051] Examples of silicone-based surfactants include polyether-modified siloxanes and polyether-modified polydimethylsiloxanes. Commercially available silicone-based surfactants may also be used. Examples of commercially available products include "Dynol 960" and "Dynol 980" from Air Products and Chemicals; "Sylface (registered trademark) SAG002," "Sylface SAG005," and "Sylface SAG503A" from Nisshin Chemical Industry Co., Ltd.; "BYK (registered trademark)-345," "BYK-347," "BYK-348," "BYK-349," "BYK-3420," "BYK-3455," "BYK-3456," "LP-X23288," "LP-X23289," and "LP-X23347" from BYK-Chemie; and "TEGO (registered trademark) Twin4000" and "TEGO Wet KL245" from Evonik Tego Chemie.

[0052] Examples of fluorine-based surfactants include perfluoroalkyl sulfonic acid compounds, perfluoroalkyl carboxylic acid compounds, perfluoroalkyl phosphate ester compounds, perfluoroalkyl ethylene oxide adducts, and polyoxyalkylene ether polymer compounds having perfluoroalkyl ether groups in their side chains.

[0053] Surfactants may be used individually or in combination of two or more types. When an aqueous ink contains a surfactant, the amount of surfactant relative to the total amount of aqueous ink is not particularly limited. The range of the amount is, for example, 0.10% by mass or more and 20.00% by mass or less, 0.15% by mass or more and 10.00% by mass or less, and 0.20% by mass or more and 5.00% by mass or less. When an aqueous ink contains a surfactant, if the amount of surfactant is within the above range, it can impart a suitable surfactant effect to the aqueous ink.

[0054] Water-based inks may also contain conventionally known additives as needed. Examples of additives include pH adjusters, viscosity modifiers, and preservatives. Examples of viscosity modifiers include polyvinyl alcohol, cellulose, and water-soluble resins.

[0055] Water-based inks can be prepared, for example, by uniformly mixing a pigment, a binder, a crosslinking agent, wax particles, water, and other components as needed, using conventionally known methods, and then removing insoluble materials using a filter or the like.

[0056] As described above, water-based inks contain solids derived from various components. The storage stability of water-based inks can be improved by appropriately setting the total amount of solids from the binder, crosslinking agent, and wax particles relative to the total amount of ink. The total amount of solids from the binder, crosslinking agent, and wax particles relative to the total amount of ink is not particularly limited. The lower limit of the total amount of solids from the binder, crosslinking agent, and wax particles relative to the total amount of ink is, for example, 5.00% by mass or more, 6.00% by mass or more, 7.00% by mass or more, and 7.20% by mass or more. The upper limit of the total amount of solids from the binder, crosslinking agent, and wax particles relative to the total amount of ink is, for example, 20.00% by mass or less, 15.00% by mass or less, 12.00% by mass or less, and 10.00% by mass or less. The range of the total amount of solids from the binder, crosslinking agent, and wax particles relative to the total amount of ink can be set by appropriately combining the upper and lower limits mentioned above. The range of the total amount of solids of the binder, crosslinking agent, and wax particles relative to the total amount of water-based ink is, for example, 5.00% by mass or more and 20.00% by mass or less, 6.00% by mass or more and 15.00% by mass or less, 7.00% by mass or more and 12.00% by mass or less, and 7.20% by mass or more and 10.00% by mass or less.

[0057] (Ink set) Next, the ink set disclosed herein will be described. The ink set comprises the above-mentioned water-based ink for inkjet recording and a pretreatment solution.

[0058] (Pretreatment solution) The pretreatment solution is applied to the fabric before forming an image on it using water-based inkjet recording ink. The pretreatment solution, for example, prevents the pigments contained in the water-based ink from seeping into the fabric. The pretreatment solution contains a coagulant.

[0059] (Flocculant) Coagulants are added to water-based inks to facilitate the aggregation of components, thereby suppressing ink bleeding and improving pigment fixation and color development. Examples of coagulants include organic acids, cationic compounds, and polyvalent metal salts.

[0060] Examples of organic acids include monocarboxylic acids and their salts such as formic acid, acetic acid, propionic acid, butyric acid, benzoic acid, glycolic acid, lactic acid, salicylic acid, pyrrole carboxylic acid, furoic acid, picolinic acid, nicotinic acid, thiophene carboxylic acid, levulinic acid, and coumaric acid; dicarboxylic acids and their salts or hydrogen salts such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, maleic acid, fumaric acid, itaconic acid, sebacic acid, phthalic acid, malic acid, and tartaric acid; tricarboxylic acids and their salts or hydrogen salts such as citric acid and trimellitic acid; and tetracarboxylic acids and their salts or hydrogen salts such as pyromellitic acid.

[0061] Examples of cationic compounds include cationic resins and cationic surfactants.

[0062] Examples of cationic resins include resins having primary, secondary, and tertiary amine structures, and resins having quaternary ammonium salt structures. Specifically, examples include resins having structures such as vinylamine, allylamine, vinylimidazole, vinylpyridine, dimethylaminoethyl methacrylate, ethyleneimine, guanidine, diallyldimethylammonium chloride, and alkylamine-epichlorohydrin condensates.

[0063] Examples of cationic surfactants include quaternary ammonium salts, quaternary ammonium ions, primary, secondary, and tertiary amine salt compounds, alkylamine salts, dialkylamine salts, aliphatic amine salts, alkylpyridinium salts, imidazolinium salts, sulfonium salts, phosphonium salts, and onium salts. Specific examples of cationic surfactants other than quaternary ammonium salts and quaternary ammonium ions include hydrochloride and acetate salts of laurylamine, coconutamine, rosinamine, etc., as well as cetylpyridinium chloride, cetylpyridinium bromide, and dihydroxyethyl laurylamine.

[0064] Examples of polyvalent metal salts include aluminum chloride, aluminum bromide, aluminum sulfate, aluminum nitrate, aluminum acetate, barium chloride, barium bromide, barium iodide, barium oxide, barium nitrate, barium thiocyanate, calcium chloride, calcium bromide, calcium iodide, calcium nitrite, calcium nitrate, calcium dihydrogen phosphate, calcium thiocyanate, calcium lactate, calcium fumarate, calcium citrate, copper chloride, copper bromide, copper sulfate, copper nitrate, copper acetate, and chloride. Examples include iron, iron bromide, iron iodide, iron sulfate, iron nitrate, iron oxalate, iron lactate, iron fumarate, iron citrate, magnesium chloride, magnesium bromide, magnesium iodide, magnesium sulfate, manganese sulfate, manganese nitrate, manganese dihydrogen phosphate, manganese acetate, manganese salicylate, manganese benzoate, manganese lactate, nickel chloride, nickel bromide, nickel sulfate, nickel nitrate, nickel acetate, tin sulfate, titanium chloride, zinc chloride, zinc bromide, zinc sulfate, zinc nitrate, zinc thiocyanate, zinc acetate, etc.

[0065] The coagulant may be one type from the above list used alone, or two or more types may be used in combination. The content of the coagulant relative to the total amount of the pretreatment liquid is not particularly limited. The range of the content is, for example, 0.50% by mass or more and 20.00% by mass or less, 1.00% by mass or more and 20.00% by mass or less, and 1.00% by mass or more and 15.00% by mass or less.

[0066] The pretreatment solution may further contain additives such as solvents, pH adjusters, and preservatives, as needed.

[0067] (Inkjet recording device) Next, the inkjet recording device 10 of the embodiment will be described with reference to the drawings. Hereinafter, the inkjet recording device 10 may be simply referred to as the recording device 10. The recording device 10 is a device that ejects water-based inkjet recording ink toward a fabric material according to an inkjet recording method and records an image toward the fabric material. In this embodiment, the recording device 10 is a device that performs printing on a fabric material by an inkjet recording method. The recording device 10 is used by being placed on a table. However, in other embodiments, the recording device 10 may be used by being placed on the floor or on a rack.

[0068] As shown in Figure 1, the recording device 10 comprises a storage tank 11, a carriage 12, a discharge head 13, a pair of transport rollers 14, a pair of guide rails 15, a sub-tank 16, and a control unit 20. The control unit 20 is communicatively connected to each part of the recording device 10 and controls the operation of each part. The control unit 20 is also communicatively connected to a pre-treatment liquid coating device 22, which will be described later, and controls the operation of the pre-treatment liquid coating device 22. The fabric material 30, which is the object of image formation, is placed on the platen of the recording device 10.

[0069] A discharge head 13 is mounted on the carriage 12. The carriage 12 is supported by a pair of guide rails 15. The carriage 12 reciprocates along the guide rails 15 in the direction of movement Ds. As a result, the discharge head 13 reciprocates in the direction of movement Ds. The direction of movement Ds is perpendicular to the direction Df of fabric material transport.

[0070] The carriage 12 is equipped with multiple sub-tanks 16. Each sub-tank 16 is connected to a corresponding storage tank 11 via a tube for circulating ink. In Figure 1, the sub-tanks 16 are schematically shown as a single structure.

[0071] A pair of conveyor rollers 14 are arranged parallel to each other along the direction of movement Ds. The conveyor rollers 14 rotate when driven by a conveyor motor, thereby conveying the fabric material 30 on the platen in the conveying direction Df.

[0072] Water-based ink is stored in the storage tank 11. The storage tank 11 is connected to the discharge head 13 via a tube and a sub-tank 16. A separate storage tank 11 is provided for each type of water-based ink. In Figure 1, the storage tank 11 is schematically shown as a single structure, but the recording device 10 may have, for example, five storage tanks 11. The five storage tanks 11 each store water-based ink of white, black, yellow, cyan, and magenta.

[0073] As shown in Figure 2, the carriage 12 is equipped with two discharge heads 13A and 13B. Discharge heads 13A and 13B are aligned along the transport direction Df. When recording an image on the fabric material 30, the carriage 12 is moved along the movement direction Ds. As a result, the discharge heads 13A and 13B move together with the carriage 12. At this time, the discharge heads 13 discharge water-based ink onto the fabric material 30, thereby recording an image on the recording surface of the fabric material 30. In the image recording process, the process of transporting the fabric material 30 in the transport direction Df and the process of moving the discharge heads 13 while discharging water-based ink are repeated alternately.

[0074] The ejection head 13A ejects white ink. The ejection head 13A is provided with a row of nozzles NL for ejecting white ink, arranged along the transport direction Df. In the example shown in Figure 2, the ejection head 13A has four rows of nozzles NL for ejecting white ink, arranged at regular intervals along the movement direction Ds. The number of nozzle rows NL for ejecting white ink is not particularly limited. For example, there may be two rows or one row of nozzles NL for ejecting white ink.

[0075] The ejection head 13B ejects water-based inks of yellow, magenta, cyan, and black. The ejection head 13B is provided with nozzle rows NL for ejecting each water-based ink, along the transport direction Df. Each nozzle row NL is arranged at a constant interval along the movement direction Ds.

[0076] In addition to the five storage tanks 11 for storing each of the aforementioned water-based inks, the recording device 10 may also include a storage tank for storing special color inks. In this case, for example, one of the nozzle rows NL of the discharge head 13A may be used to discharge the special color ink.

[0077] (Image forming method) Next, an image formation method using an inkjet recording method with a recording device 10 will be described. This image formation method comprises a pre-treatment step, a pre-treatment liquid fixing step, an image formation step, and a drying step. The control unit 20 executes each step in response to, for example, a command to form an image being input to the recording device 10 from an external source. When the command is input, the control unit 20 transports the fabric material 30 by controlling various parts such as a pair of transport rollers 14.

[0078] (Pre-treatment process) In the pretreatment step, the control unit 20 applies a pretreatment solution to the recording surface of the cloth material 30. The pretreatment step is performed with the aim of suppressing the bleeding of water-based ink and improving the fixation and color development of pigments. The specific configuration for applying the pretreatment solution to the cloth material 30 is not particularly limited. For example, as shown in Figure 3, the pretreatment solution can be applied to the cloth material 30 using a pretreatment solution application device 22 that is independent of the recording device 10. The control unit 20 controls the operation of the pretreatment solution application device 22 to apply the pretreatment solution to the recording surface of the cloth material 30 as it passes through the pretreatment solution application device 22.

[0079] The method of applying the pretreatment solution to the fabric material 30 is not particularly limited. Examples of pretreatment solution application methods include spray coating, blade coating, roll coating, inkjet, and immersion processing methods. The immersion processing method involves immersing the fabric material 30 in the pretreatment solution and then squeezing the fabric material 30 with a mangle roll. From the viewpoint of continuously performing the application of the pretreatment solution and image formation with water-based ink, an inkjet method may be adopted.

[0080] In the pretreatment step, the pretreatment solution is applied to the image-forming area with water-based ink. The pretreatment solution may be applied to the entire recording surface of the cloth material 30, or to only a portion of the area including the image-forming area. In the former case, a spray coating method, blade coating method, roll coating method, immersion processing method, etc., can be suitably employed. In the latter case, an inkjet method can be suitably employed.

[0081] Furthermore, the recording device 10 itself may also have the function of a pretreatment liquid coating device 22. That is, the recording device 10 may be configured to coat the fabric material 30 with pretreatment liquid. Also, if the pretreatment liquid is coated by an inkjet method, a separate discharge head for coating the pretreatment liquid may be provided on the carriage 12 of the recording device 10.

[0082] (Pretreatment solution fixing process) In the pretreatment solution fixing process, the control unit 20 fixes the pretreatment solution applied to the cloth material 30 to the recording surface of the cloth material 30 by drying it. The control unit 20 fixes the pretreatment solution to the recording surface of the cloth material 30 by controlling the drying device provided in the pretreatment solution application device 22.

[0083] The method for drying the pretreatment solution is not particularly limited. Examples of pretreatment solution drying methods include air drying and heating with equipment. Examples of equipment include commercially available irons, heat presses, dryers, ovens, and belt conveyor ovens.

[0084] (image forming process) In the image forming process, the control unit 20 ejects water-based ink onto the recording surface of the transported fabric material 30. The control unit 20 controls piezoelectric elements, etc., corresponding to each nozzle provided on the carriage 12 and the ejection head 13, to selectively eject water-based ink from each nozzle toward the fabric material 30 passing below the ejection head 13. As a result, a predetermined image is formed on the recording surface of the fabric material 30.

[0085] (drying process) In the drying process, the control unit 20 heats the fabric material 30 coated with water-based ink to dry the water-based ink. The control unit 20 controls, for example, a drying device provided in the recording device 10 to dry the water-based ink adhering to the recording surface of the fabric material 30. As a method for drying the water-based ink, various drying methods described above in the pretreatment liquid fixing process can be employed. In the drying process, by heating and drying the fabric material 30 on which the image has been recorded, the pigment can be fixed more effectively to the fibers constituting the fabric material 30.

[0086] The heating temperature of the fabric material 30 in the drying process is not particularly limited. The lower limit of the heating temperature is, for example, 80°C or higher, 100°C or higher, 110°C or higher, or 130°C or higher. The upper limit of the heating temperature is, for example, 200°C or lower, 190°C or lower, 185°C or lower, or 180°C or lower. The range of the heating temperature can be set by appropriately combining the upper and lower limits mentioned above. The range of the heating temperature is, for example, 80°C or higher and 200°C or lower, 100°C or higher and 190°C or lower, 110°C or higher and 185°C or lower, or 130°C or higher and 180°C or lower. From the viewpoint of forming a resin coating film by heat treatment, the heating temperature should be above the glass transition temperature of the urethane resin. From the viewpoint of dissociating the blocking agent by heat treatment and promoting the crosslinking reaction, the heating temperature should be above the dissociation temperature of the blocked isocyanate compound. From the viewpoint of melting the wax particles by heat treatment and distributing some of the wax particles so as to cover the surface of the resin coating, the heating temperature should preferably be above the melting point of the wax particles. The time for drying the same position on the fabric material 30 is not particularly limited, but can be, for example, 120 seconds or more and 600 seconds or less.

[0087] In the above-described embodiment, the control unit 20 of the recording device 10 controlled the operation of the pretreatment liquid coating device 22. However, a separate dedicated control unit for controlling the pretreatment liquid coating device 22 may be provided. Furthermore, the pretreatment liquid fixing step does not have to be performed after the pretreatment step, or neither the pretreatment step nor the pretreatment liquid fixing step may be performed. In other words, the image forming method disclosed herein only needs to include at least an image forming step and a drying step. [Examples]

[0088] Next, the aqueous inks disclosed herein will be described in detail with reference to examples and comparative examples. However, the technologies disclosed herein are not limited in any way to these examples.

[0089] (Preparation of the aqueous ink in Example 1) A total of 89.55% by mass of a water-soluble organic solvent and water was prepared. To this water-soluble organic solvent and water, 5.50% by mass of Takelac W-6110 as a binder (based on solid content), 1.20% by mass of SU-268A as a crosslinking agent (based on solid content), 0.50% by mass of Hi-Tec E-6314 as wax particles (based on solid content), and 0.25% by mass of BYK-3420 as a surfactant were added and mixed. Finally, 3.00% by mass of black pigment dispersion (based on solid content) was added and mixed as a pigment. The resulting mixture was filtered through a cellulose acetate type membrane filter (pore size 3.00 μm) manufactured by Toyo Roshi Co., Ltd. to obtain the aqueous ink of Example 1.

[0090] (Preparation of aqueous inks for Examples 2-19 and Comparative Examples 1-3) Except for the types and amounts of components described in Tables 1-3, the same procedure as for preparing the aqueous ink in Example 1 was followed to obtain the aqueous inks for each example.

[0091] [Table 1]

[0092] [Table 2]

[0093] [Table 3]

[0094] In Tables 1 to 3, the black pigment dispersion is an aqueous dispersion of carbon black, and the magenta pigment dispersion is an aqueous dispersion of CI Pigment Red 122. Furthermore, the content of each component in each example represents the solid content or active ingredient content of that component relative to the total amount of aqueous ink.

[0095] (Preparation of evaluation samples) As a pretreatment step, a 350mm x 350mm piece of 100% cotton white woven fabric was coated with 80.00 g / m2 of a calcium nitrate aqueous solution diluted to 0.30% by mass as a pretreatment solution, and dried in an oven set to 120°C for 3 minutes to obtain a pretreated woven fabric. The pretreated woven fabric was set in a Brother Industries, Ltd. GTX® pro garment printer. Using the water-based inks prepared for each example, the amount ejected from the inkjet head was adjusted to 20 pL per pixel, and an image was formed on the pretreated woven fabric by solid printing at a resolution of 1200 dpi x 1200 dpi. After image formation, the pretreated woven fabric was heated in an oven set to 160°C for 5 minutes to obtain an evaluation sample.

[0096] For each example and comparative example, the storage stability, dry rubbing fastness, and wet rubbing fastness of the ink were evaluated according to the methods described below.

[0097] (Evaluation of ink storage stability) Each prepared aqueous ink sample was placed in a sealed container and stored for one week in a constant temperature bath manufactured by ESPEC Corporation and set to 60°C. The viscosity before and after one week of storage was measured at 25°C using a TVE-25 viscometer manufactured by Toki Sangyo Co., Ltd. The percentage change in viscosity after storage compared to before storage was calculated, and the storage stability of the aqueous ink was evaluated according to the following criteria. The evaluation results are shown in Tables 1 to 3. A: The rate of change is less than 7.0% B: Rate of change is between 7.0% and less than 15.0% C: Change rate of 15.0% or more

[0098] (Evaluation of dry friction fastness) For each example, the dry rub fastness grade was calculated for the evaluation sample using a test method compliant with ISO 105-X12, and the dry rub fastness of the water-based ink was evaluated according to the following criteria. The evaluation results and dry rub fastness grades are shown in Tables 1 to 3. AA: 4-5 grade or higher A: 4th grade B:3-4 grade C: Grade 3 or below

[0099] (Evaluation of wet friction fastness) For each example, the wet rub fastness grade was calculated for the evaluation sample using a test method compliant with ISO 105-X12, and the wet rub fastness of the water-based ink was evaluated according to the following criteria. The evaluation results and wet rub fastness grades are shown in Tables 1 to 3. AA: Level 4 or above A: Level 3-4 B: 3rd grade C: Level 2-3 or below

[0100] As shown in Tables 1 to 3, good results were obtained for all evaluation items in Examples 1 to 19. The aqueous inks of Examples 1 to 19 contain wax particles. Therefore, during the process of forming the resin coating film, some of the wax particles are distributed to cover the surface of the resin coating film. Consequently, the lubricity of the surface of the resin coating film is improved, and high dry friction fastness is obtained. On the other hand, if the wax particles melt during the heat treatment for forming the resin coating film, there is a risk that the crosslinking reaction between the binders by the crosslinking agent will be inhibited. However, the melting point of the wax particles contained in the aqueous inks of each example is relatively high, between 90°C and 140°C. Therefore, the timing of the start of melting of the wax particles during the heat treatment for forming the resin coating film can be delayed. Consequently, in the aqueous inks of each example, the wax particles begin to melt after the crosslinking reaction has progressed to a certain extent. In other words, the crosslinking reaction proceeds before the wax particles melt, and high coating film strength is obtained. As a result, high dry friction fastness and high wet friction fastness are obtained.

[0101] In contrast, Comparative Example 1 showed lower dry friction fastness compared to Example 1. The aqueous ink of Comparative Example 1 has the same composition as the aqueous ink of Example 1, except that it does not contain wax particles. Therefore, the aqueous ink of Comparative Example 1 does not contain wax particles to cover the surface of the resin coating film, and thus cannot impart good abrasion resistance to the resin coating film. This is thought to be the reason for the lower dry friction fastness.

[0102] Furthermore, Comparative Example 2 showed particularly low wet friction fastness compared to Example 1. The aqueous ink of Comparative Example 2 has the same composition as the aqueous ink of Example 1, except that it does not contain a crosslinking agent. Therefore, it is thought that Comparative Example 2 failed to form a crosslinking structure between the binders and thus could not obtain sufficient coating strength, resulting in low wet friction fastness.

[0103] Furthermore, Comparative Example 3 showed particularly low dry friction fastness compared to Example 1. The aqueous ink of Comparative Example 3 has the same composition as the aqueous ink of Example 1, except that it contains different wax particles. Specifically, the melting point of "AQUACER593," the wax particle contained in the aqueous ink of Comparative Example 3, is 160°C. On the other hand, the melting point of "HITEC E-6314," the wax particle contained in the aqueous ink of Example 1, is 137°C. In other words, the melting point of the wax particles of Comparative Example 3 is equivalent to the heating temperature of 160°C when the evaluation sample was prepared, and the wax particles do not melt sufficiently, so the wax particles do not distribute enough to cover the surface of the resin coating film. Therefore, it is thought that this resulted in low dry friction fastness.

[0104] Next, we will compare and examine each example. The aqueous inks of Examples 2 to 4 have the same composition as the aqueous ink of Example 1, except that they contain different binders, although they are urethane-based resins. In all evaluations, Examples 2 to 4 yielded results equivalent to those of Example 1. Therefore, it is considered that the technology disclosed herein can be applied to various aqueous inks containing urethane-based resins as binders.

[0105] The aqueous inks of Examples 5-10 have the same composition as the aqueous ink of Example 1, except that they contain different wax particles. The aqueous inks of Examples 1 and 5-10 contain wax particles with different melting points. Among Examples 1 and 5-10, Examples 6 and 7 showed inferior dry friction fastness. The wax particles contained in the aqueous inks of Examples 6 and 7 are modified paraffin wax, a type of paraffin wax. On the other hand, the wax particles contained in the aqueous inks of Examples 5 and 10 are oxidized polyethylene wax. The wax particles contained in the aqueous inks of Examples 1, 8, and 9 are polyethylene wax. It was confirmed that aqueous inks containing polyethylene wax, which has excellent abrasion resistance, exhibited better dry friction fastness.

[0106] Furthermore, among Examples 1, 5, and 8-10, Example 9 showed slightly inferior dry friction fastness. The melting point of the polyethylene wax contained in the aqueous ink of Example 9 was the lowest among the polyethylene waxes contained in the aqueous inks of Examples 1, 5, and 8-10, and was lower than the heating temperature. In the heat treatment to form the resin coating film, the wax particles melt and are distributed to cover the surface of the resin coating film. The wax particles of the aqueous ink of Example 9 did not melt sufficiently during the heat treatment and did not sufficiently cover the surface of the resin coating film, resulting in slightly lower dry friction fastness. On the other hand, by melting the wax particles so that at least a part of the shape of the wax particles remains, rather than completely melting them, the dry friction fastness can be further improved. This is thought to be because, when the surface of the resin coating film is rubbed, the wax particles are scraped off before other components because the particle shape of the wax particles remains to some extent on the surface of the resin coating film. This suppresses the direct application of frictional force to the binder. Therefore, it is believed that the dry friction fastness can be further improved by raising the melting point of polyethylene-based wax to a certain extent, within a range where it does not completely melt at the heating temperature.

[0107] The melting points of the wax particles contained in the aqueous inks of Examples 1, 5, 8, and 10 are somewhat higher than the dissociation temperature of the blocked isocyanate compound. Specifically, the melting points of the wax particles are 5°C or more higher than the dissociation temperature. If the melting point of the wax particles is lower than the dissociation temperature of the blocked isocyanate compound, the wax particles will melt during the heat treatment before the blocking agent actively dissociates. The melted wax particles will inhibit the crosslinking reaction, and sufficient coating strength cannot be obtained. Therefore, it is considered that the aqueous inks of Examples 1, 5, 8, and 10, in which the melting point of the wax particles is somewhat higher than the dissociation temperature of the blocked isocyanate compound, exhibited good wet friction fastness. Furthermore, since a crosslinked structure is formed between the binders by the crosslinking agent, it is preferable that the crosslinking reaction starts after the coating film formation by the binder has begun. Therefore, it is considered that further improvement in coating strength can be achieved by making the dissociation temperature of the blocked isocyanate compound higher than the glass transition temperature of the urethane resin, which is the binder.

[0108] Furthermore, among Examples 1, 5, 8, and 10, Examples 1 and 8 showed superior wet friction fastness. The melting points of the wax particles contained in the aqueous inks of Examples 5 and 10 are higher than the dissociation temperatures of the blocked isocyanate compounds, but the difference is relatively small. On the other hand, the melting points of the wax particles contained in the aqueous inks of Examples 1 and 8 are 15°C or more higher than the dissociation temperatures of the blocked isocyanate compounds. If the melting point of the wax particles is close to the dissociation temperature of the blocked isocyanate compounds, the timing of the melting of the wax particles during heat treatment may coincide with the timing of the active dissociation of the blocking agent. The melted wax particles become a factor that inhibits the crosslinking reaction, and sufficient coating strength cannot be obtained. If the melting point of the wax particles is 15°C or more higher than the dissociation temperature of the blocked isocyanate compounds, the wax particles begin to melt after the crosslinking reaction has progressed, so it is thought that the wet friction fastness can be further improved.

[0109] The aqueous inks of Examples 11 and 12 have the same composition as the aqueous ink of Example 1, except that they contain different crosslinking agents. In other words, the aqueous inks of Examples 1, 11, and 12 contain blocked isocyanate compounds with different dissociation temperatures. As shown in Tables 1 to 3, the closer the dissociation temperature of the blocked isocyanate compound is to the heating temperature during the preparation of the evaluation sample, the lower the wet friction fastness may be. For example, Example 12 showed lower wet friction fastness compared to Examples 1 and 11. The dissociation temperature of the blocked isocyanate compound in Example 12, 160°C, is the highest among Examples 1, 11, and 12, and is equivalent to the heating temperature of 160°C. When the dissociation temperature of the blocked isocyanate compound is equivalent to or close to the heating temperature, it is thought that the blocking agent bonded to the isocyanate group does not dissociate sufficiently during the heat treatment, and the crosslinking reaction does not proceed easily. Therefore, it is thought that sufficient coating strength cannot be obtained, and the wet friction fastness may decrease. Therefore, aqueous inks containing blocked isocyanate compounds with a dissociation temperature lower than the heating temperature are expected to exhibit better wet friction fastness.

[0110] On the other hand, Examples 1, 11, and 12 confirmed that the lower the dissociation temperature of the blocked isocyanate compound, the lower the storage stability of the aqueous ink may be. In particular, Example 11 showed inferior storage stability of the aqueous ink compared to Examples 1 and 12. The dissociation temperature of the blocked isocyanate compound contained in the aqueous ink of Example 11 was the lowest among the dissociation temperatures of the blocked isocyanate compounds contained in the aqueous inks of Examples 1, 11, and 12. It is thought that the lower the dissociation temperature, the more the blocking agent dissociates from the isocyanate group during storage of the aqueous ink, and the more the crosslinking reaction proceeds unintentionally. This is thought to increase the viscosity of the aqueous ink and reduce its storage stability. Therefore, it is thought that raising the dissociation temperature of the blocked isocyanate compound to a certain extent can result in better storage stability of the aqueous ink.

[0111] The relationship between the melting point of the wax particles and the dissociation temperature of the blocked isocyanate compound was also observed in Examples 1, 11, and 12. Specifically, the melting point of the wax particles contained in the aqueous ink of Example 12 was lower than the dissociation temperature of the blocked isocyanate compound. On the other hand, the melting points of the wax particles contained in the aqueous inks of Examples 1 and 11 were more than 15°C higher than the dissociation temperature of the blocked isocyanate compound. As a result, Example 12 showed inferior wet friction fastness compared to Examples 1 and 11. Thus, in Examples 1, 11, and 12, it was confirmed that a good wet friction fastness is obtained when the melting point of the wax particles is more than 15°C higher than the dissociation temperature.

[0112] The aqueous inks of Examples 13 and 14 have the same composition as the aqueous ink of Example 6, except that they contain different crosslinking agents. The crosslinking agents contained in the aqueous inks of Examples 6, 13, and 14 are all blocked isocyanate compounds, but their dissociation temperatures differ. From Examples 6, 13, and 14, it was found that the closer the dissociation temperature of the blocked isocyanate compound is to the heating temperature during the preparation of the evaluation sample, the lower the wet friction fastness may be. The aqueous inks of Examples 6 and 14, in which the dissociation temperature of the blocked isocyanate compound is somewhat lower than the heating temperature, exhibited better wet friction fastness than Example 13. Furthermore, from Examples 6, 13, and 14, it was confirmed that the lower the dissociation temperature of the blocked isocyanate compound, the lower the storage stability of the aqueous ink may be. In particular, the storage stability of the aqueous inks of Examples 6 and 13, in which the dissociation temperature of the blocked isocyanate compound is relatively high, was equivalent to that of Examples 1, 11, and 12, and was superior to that of Example 14.

[0113] The aqueous ink of Example 13 has the same composition as the aqueous ink of Example 12, except that it contains different wax particles. The wax particles contained in the aqueous ink of Example 13 are modified paraffin wax, a type of paraffin wax. On the other hand, the wax particles contained in the aqueous ink of Example 12 are polyethylene wax. Example 13 showed inferior dry rub fastness compared to Example 12. In other words, it was confirmed that aqueous inks containing polyethylene wax as wax particles exhibit better dry rub fastness. Furthermore, it was also confirmed from Examples 1, 5 to 11 and 14 that aqueous inks containing polyethylene wax as wax particles exhibit better dry rub fastness.

[0114] The aqueous inks of Examples 15 and 16 have the same composition as the aqueous ink of Example 1, except that the crosslinking agent content differs. In other words, the aqueous inks of Examples 1, 15, and 16 differ in the ratio of crosslinking agent content to binder content. The aqueous ink of Example 15, with a ratio of 0.55, showed poor storage stability. Blocked isocyanate compounds can slightly dissociate as a blocking agent even during storage of aqueous ink. Therefore, the higher the crosslinking agent content, the more blocking agent dissociates, making the crosslinking reaction more likely to proceed, and thus increasing the viscosity of the aqueous ink. For this reason, aqueous inks with a relatively small ratio are thought to have better storage stability.

[0115] Furthermore, in Example 16, where the above ratio was 0.09, the wet friction fastness was inferior. Generally, as the crosslinking agent content increases, more crosslinked structures are formed by heat treatment. Therefore, the lower the crosslinking agent content, the fewer crosslinked structures are formed by heat treatment, making it difficult to obtain sufficient coating strength. For this reason, it is thought that water-based inks with a sufficiently large above ratio will obtain better wet friction fastness.

[0116] The aqueous inks of Examples 17 and 18 have the same composition as the aqueous ink of Example 1, except that they contain different amounts of wax particles. In other words, the aqueous inks of Examples 1, 17, and 18 differ in the amount of wax particles relative to the total amount of aqueous ink. The aqueous ink of Example 17, which contains 1.50% by mass of wax particles, showed poor storage stability. Generally, wax particles have the effect of increasing the viscosity of aqueous ink. Therefore, the greater the amount of wax particles relative to the total amount of aqueous ink, the greater the increase in viscosity of the aqueous ink. For this reason, aqueous inks with a relatively small amount of wax particles relative to the total amount of aqueous ink are thought to have better storage stability.

[0117] Furthermore, in Example 18, where the above content was 0.30% by mass, the dry friction fastness was inferior. Generally, the presence of wax particles on the surface of a resin coating improves the lubricity of the resin coating. Therefore, the lower the above content, the less the lubricity-improving effect of the wax particles is obtained. For this reason, it is thought that water-based inks containing a certain amount of wax particles will obtain better dry friction fastness.

[0118] The aqueous ink of Example 19 has the same composition as the aqueous ink of Example 1, except that it contains a different pigment. In all evaluations, Example 19 yielded the same results as Example 1. Therefore, it is considered that the technology disclosed herein can be applied to aqueous inks containing various pigments.

[0119] From these results, it was found that an aqueous ink containing a urethane-based resin as a binder and a blocked isocyanate compound as a crosslinking agent exhibits high friction fastness by setting the melting point of the wax particles between 90°C and 140°C.

[0120] Although specific examples of the present invention have been described in detail above, these are merely illustrative and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes to the specific examples illustrated above.

[0121] Furthermore, the technical elements described herein or in the drawings demonstrate technical usefulness individually or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technologies illustrated herein or in the drawings can achieve multiple objectives simultaneously, and achieving even one of these objectives itself constitutes technical usefulness.

[0122] Even if, in the claims of this patent application, each claim depends on only some of the claims, it is not limited to the claim being dependent only on those specific claims. To the extent that it is not technically contradictory, each claim may be dependent on other claims that were not dependent at the time of application. That is, the technologies of each claim can be combined in various ways as follows: (Item 1) An inkjet water-based ink used to form an image on a fabric material, Pigments and Binder and, Crosslinking agent and wax particles and Equipped with, The binder contains a urethane resin, The crosslinking agent comprises a blocked isocyanate compound. The melting point of the wax particles is between 90°C and 140°C. Water-based ink for inkjet recording. (Item 2) The aqueous inkjet recording ink according to item 1, wherein the dissociation temperature of the blocked isocyanate compound is 130°C or lower. (Item 3) The aqueous inkjet recording ink according to item 1 or 2, wherein the dissociation temperature of the blocked isocyanate compound is 120°C or higher. (Item 4) The aforementioned wax particles comprise at least one of polyethylene wax and oxidized polyethylene wax, wherein the water-based inkjet recording ink is as described in any one of items 1 to 3. (Item 5) The aqueous inkjet recording ink according to item 4, wherein the melting point of at least one of the polyethylene wax and the oxidized polyethylene wax is 125°C or higher. (Item 6) The dissociation temperature of the blocked isocyanate compound is higher than the glass transition temperature of the urethane resin. The water-based inkjet recording ink according to any one of items 1 to 5, wherein the melting point of the wax particles is 5°C or higher than the dissociation temperature of the blocked isocyanate compound. (Item 7) The aqueous inkjet recording ink according to item 6, wherein the melting point of the wax particles is 15°C or higher than the dissociation temperature of the blocked isocyanate compound. (Item 8) The water-based inkjet recording ink according to any one of items 1 to 7, wherein the content of the wax particles relative to the total amount of the water-based inkjet recording ink is 1.00% by mass or less. (Item 9) The water-based inkjet recording ink according to any one of items 1 to 8, wherein the content of the wax particles relative to the total amount of the water-based inkjet recording ink is 0.50% by mass or more. (Item 10) An inkjet water-based ink for recording according to any one of items 1 to 9, wherein the ratio of the content of the crosslinking agent to the content of the binder is 0.50 or less. (Item 11) An inkjet water-based ink for recording according to any one of items 1 to 10, wherein the ratio of the content of the crosslinking agent to the content of the binder is 0.10 or more. (Item 12) A water-based inkjet recording ink described in any of items 1 through 11, An ink set comprising a pretreatment liquid applied to a fabric material before forming an image on the fabric material using the aforementioned water-based inkjet recording ink. (Item 13) An inkjet recording apparatus comprising an ink storage section, an ink ejection section, and an aqueous inkjet recording ink stored in the ink storage section, wherein the aqueous inkjet recording ink is ejected from the ink ejection section to form an image on a fabric material, The aforementioned water-based inkjet recording ink is It comprises a pigment, a binder, a crosslinking agent, and wax particles. The binder contains a urethane resin, The crosslinking agent comprises a blocked isocyanate compound. The melting point of the wax particles is between 90°C and 140°C. Inkjet recording device. (Item 14) An image forming method for forming an image on a fabric material using an inkjet recording method, An image forming step in which an image is formed on the aforementioned fabric material using an inkjet recording aqueous ink, A drying step in which the water-based ink for inkjet recording is dried by heating the fabric material on which the image has been formed, Equipped with, The aforementioned water-based inkjet recording ink comprises a pigment, a binder, a crosslinking agent, and wax particles. The binder contains a urethane resin, The crosslinking agent comprises a blocked isocyanate compound. The melting point of the wax particles is between 90°C and 140°C. Image forming method. (Item 15) The image forming method according to item 14, wherein the drying step involves a heating temperature of 160°C or higher. (Item 16) The image forming method according to item 14 or 15, further comprising a pretreatment step of applying a pretreatment liquid to the fabric material before the image forming step, wherein the pretreatment liquid is applied to an area where an image is formed by the water-based inkjet recording ink. [Explanation of Symbols]

[0123] 10: Inkjet recording device, 11: Storage tank, 12: Carriage, 13: Discharge head, 14: Conveyor roller, 15: Guide rail, 16: Sub-tank, 20: Control unit, 22: Pretreatment liquid coating device, 30: Fabric material

Claims

1. An inkjet water-based ink used to form an image on a fabric material, Pigments and Binder and, Crosslinking agent and wax particles and Equipped with, The binder contains a urethane resin, The crosslinking agent comprises a blocked isocyanate compound. The melting point of the wax particles is between 90°C and 140°C. Water-based ink for inkjet recording.

2. The aqueous inkjet recording ink according to claim 1, wherein the dissociation temperature of the blocked isocyanate compound is 130°C or lower.

3. The aqueous inkjet recording ink according to claim 2, wherein the dissociation temperature of the blocked isocyanate compound is 120°C or higher.

4. The aqueous inkjet recording ink according to claim 3, wherein the wax particles include at least one of polyethylene wax and oxidized polyethylene wax.

5. The aqueous inkjet recording ink according to claim 4, wherein the melting point of at least one of the polyethylene wax and the oxidized polyethylene wax is 125°C or higher.

6. The dissociation temperature of the blocked isocyanate compound is higher than the glass transition temperature of the urethane resin. The aqueous inkjet recording ink according to claim 5, wherein the melting point of the wax particles is 5°C or higher than the dissociation temperature of the blocked isocyanate compound.

7. The aqueous inkjet recording ink according to claim 6, wherein the melting point of the wax particles is 15°C or higher than the dissociation temperature of the blocked isocyanate compound.

8. The water-based inkjet recording ink according to claim 1, wherein the content of the wax particles relative to the total amount of the water-based inkjet recording ink is 1.00% by mass or less.

9. The water-based inkjet recording ink according to claim 8, wherein the content of the wax particles relative to the total amount of the water-based inkjet recording ink is 0.50% by mass or more.

10. The aqueous inkjet recording ink according to claim 1, wherein the ratio of the content of the crosslinking agent to the content of the binder is 0.50 or less.

11. The aqueous inkjet recording ink according to claim 10, wherein the ratio of the content of the crosslinking agent to the content of the binder is 0.10 or more.

12. An aqueous inkjet recording ink according to any one of claims 1 to 11, A pretreatment liquid applied to the fabric material before forming an image on the fabric material using the aforementioned water-based inkjet recording ink, An ink set equipped with this feature.

13. An inkjet recording apparatus comprising an ink storage section, an ink ejection section, and an aqueous inkjet recording ink stored in the ink storage section, wherein the aqueous inkjet recording ink is ejected from the ink ejection section to form an image on a fabric material, The aforementioned water-based inkjet recording ink comprises a pigment, a binder, a crosslinking agent, and wax particles. The binder contains a urethane resin, The crosslinking agent comprises a blocked isocyanate compound. The melting point of the wax particles is between 90°C and 140°C. Inkjet recording device.

14. An image forming method for forming an image on a fabric material using an inkjet recording method, comprising: an image forming step of forming an image on the fabric material with an inkjet recording aqueous ink; A drying step in which the water-based ink for inkjet recording is dried by heating the fabric material on which the image has been formed, Equipped with, The aforementioned water-based inkjet recording ink comprises a pigment, a binder, a crosslinking agent, and wax particles. The binder contains a urethane resin, The crosslinking agent comprises a blocked isocyanate compound. The melting point of the wax particles is between 90°C and 140°C. Image forming method.

15. The image forming method according to claim 14, wherein the heating temperature in the drying step is 160°C or higher.

16. The image forming method according to claim 14, further comprising a pretreatment step of applying a pretreatment liquid to the fabric material before the image forming step, wherein the pretreatment liquid is applied to an area in which an image is formed by the water-based inkjet recording ink.

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