Water-based inkjet ink composition and recording method

Abstract

To provide a water-based inkjet ink composition which has excellent storage stability and discharge stability, can suitably recover from clogging in an inkjet nozzle even when the clogging occurs and can effectively suppress curling of a recording medium when recording is performed by applying to the recording medium and further to provide a recording method capable of effectively suppressing curling of a recording medium to which the water-based inkjet ink composition is applied.SOLUTION: There is provided a water-based inkjet ink composition which comprises a coloring material, inorganic oxide particles, a dispersant and a dispersing medium containing water. The inorganic oxide particles are dispersed in the dispersing medium by the dispersant. The dispersant preferably is a polymer dispersant. The content of the dispersant preferably is 20 pts.mass or more and 100 pts.mass or less based on 100 pts.mass of the inorganic oxide particles.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a water-based ink-jet ink composition and a recording method. [Background technology]

[0002] Conventionally, water-based ink-jet inks containing water as a dispersion medium or solvent have been used. Water-based inkjet inks are preferable in terms of their environmental impact and safety to the human body, as compared with solvent-based inkjet inks that contain organic solvents instead of water.

[0003] On the other hand, when plain paper or the like is used as a recording medium, conventionally, water-based inkjet inks sometimes caused curling after recording.

[0004] In order to prevent such problems, there have been attempts to incorporate silica into the ink (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2020-176235 A Summary of the Invention [Problem to be solved by the invention]

[0006] By including inorganic oxide particles in the ink, it is possible to obtain the effect of suppressing curling of the recording medium after recording, but there is a tendency for the nozzles of the inkjet head to become clogged more easily, and for the ejection stability of the ink to deteriorate when using the inkjet method. [Means for solving the problem]

[0007] The present invention has been made to solve the above-mentioned problems, and can be realized as the following application examples.

[0008] The water-based ink-jet ink composition according to an embodiment of the present invention contains a colorant, inorganic oxide particles, a dispersant, and a dispersion medium containing water, The inorganic oxide particles are dispersed in the dispersion medium by the dispersant.

[0009] In the recording method according to the application example of the present invention, the water-based ink-jet ink composition according to the application example of the present invention is ejected from an ink-jet head to record. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a table summarizing the conditions for the water-based ink-jet ink compositions prepared in each of the Examples and Comparative Examples. [Diagram 2] FIG. 2 is a table showing the evaluation results for each of the examples and comparative examples. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Preferred embodiments of the present invention will now be described in detail. [1] Water-based inkjet ink composition First, the water-based ink-jet ink composition of the present invention will be described.

[0012] The water-based ink-jet ink composition of the present invention contains a colorant, inorganic oxide particles, a dispersant, and a dispersion medium containing water. The inorganic oxide particles are dispersed in the dispersion medium by the dispersant.

[0013] With this configuration, the storage stability and ejection stability of the water-based inkjet ink composition are sufficiently excellent, and even if clogging occurs in the inkjet nozzle, the inkjet nozzle can be suitably restored. Furthermore, when the water-based inkjet ink composition is applied to a recording medium for recording, curling of the recording medium can be effectively suppressed.

[0014] On the other hand, if the above conditions are not met, satisfactory results will not be obtained. For example, if the aqueous inkjet ink composition does not contain inorganic oxide particles, when the aqueous inkjet ink composition is applied to a recording medium for recording, curling of the recording medium, particularly a recording medium containing cellulose fibers such as plain paper, cannot be sufficiently suppressed.

[0015] Furthermore, when the aqueous ink-jet ink composition contains inorganic oxide particles, if it does not contain a dispersant that disperses the inorganic oxide particles in a dispersion medium, the nozzles of the ink-jet head are likely to become clogged, and the ejection stability of the ink by the ink-jet method is deteriorated. In particular, when the aqueous ink-jet ink composition in the ink-jet head becomes dried to a high degree, the redispersibility of the inorganic oxide particles is significantly reduced, and even if the ink-jet head is cleaned, the ejection stability of the aqueous ink-jet ink composition cannot be sufficiently restored.

[0016] [1-1] About inkjet Hereinafter, the water-based ink-jet ink composition of the present invention is ejected by an ink-jet method.

[0017] Since the ink is discharged by the inkjet method, for example, the recording part to be formed using the aqueous inkjet ink composition can be suitably formed even if it is a fine pattern. In addition, the recording part can be suitably formed on a curved surface or the like. In addition, the ink is excellent in on-demand property, and recording parts of various patterns can be suitably formed. In addition, the ink can be prevented from being wasted, which is preferable from the viewpoint of resource saving, etc.

[0018] Examples of the inkjet method include on-demand methods such as a charge deflection method, a continuous method, a piezoelectric method, and a bubble jet (registered trademark) method.

[0019] [1-2] Coloring materials The water-based ink-jet ink composition of the present invention contains a coloring material.

[0020] Examples of the coloring material include various pigments such as organic pigments and inorganic pigments, and various dyes. One or a combination of two or more selected from these may be used.

[0021] 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 perylene pigments, anthraquinone pigments, quinacridone pigments, dioxandinone pigments, thioindigo pigments, isoindolinone pigments, and quinophthaloni pigments; dye lakes such as basic dye lakes and acid dye lakes; nitro pigments, nitroso pigments, aniline black, and daylight fluorescent pigments.

[0022] Examples of inorganic pigments include titanium oxide, iron oxide, carbon black, etc. Carbon black that can be used includes those produced by known methods such as the contact method, furnace method, and thermal method.

[0023] As the pigment, a self-dispersing surface-treated pigment in which a hydrophilic group is introduced onto the surface of the pigment particle by utilizing a chemical reaction, that is, a so-called self-dispersing pigment, may be used.

[0024] Examples of dyes include sublimation dyes, oil dyes, disperse dyes, fluorescent dyes, reactive dyes, acid dyes, sulfur dyes, vat dyes, and cationic dyes.

[0025] Examples of disperse dyes and sublimation dyes include CI Disperse Yellow 1, 3, 4, 5, 7, 9, 13, 23, 24, 30, 33, 34, 42, 44, 49, 50, 51, 54, 56, 58, 60, 61, 63, 64, 66, 68, 71, 74, 76, 79, 82, 83, 85, 86, 88, 90, 91, 93, 98, 99, 100, 104, 108, 114, 116, 118, 119, 122, 124, 126, 135, 140, 141, 149, 154, 160, 162, 163, 164, 165, 179, 180, 182, 183, 184, 185, 186, 187, 188, 189, 190, 191, 192, 193, 194, 195, 196, 197, 198, 19 ... 6, 192, 198, 199, 201, 202, 204, 210, 211, 215, 216, 218, 224, 227, 231, 232;CI Disperse Orange 1, 3, 5, 7, 11, 13, 17, 20, 21, 25, 29, 30, 31, 32, 33, 37, 38, 42, 43, 44, 45, 46, 47, 48, 49, 50, 53, 54, 55, 56, 57, 58, 59, 60, 61, 66, 71, 73, 76, 78, 80, 89, 90, 91, 93, 96, 97, 119, 127, 130, 139, 142;CI Disperse Red 1, 4, 5, 7, 11, 12, 13, 15, 17, 27, 43, 44, 50, 52, 53, 54, 55, 56, 58, 59, 60, 65, 72, 73, 74, 75, 76, 78, 81, 82, 86, 88, 90, 91, 92, 93, 96, 103, 105, 106, 107, 108, 110, 111, 113, 117, 118, 121, 122, 126, 127, 128, 131, 132, 134, 135, 137, 143, 145, 146, 151, 152, 153, 154, 157, 159, 164, 167, 169, 177, 179, 181, 183, 184, 185, 188, 189, 190, 191, 192, 200, 201, 202, 203, 205, 206, 207, 210, 221, 224, 225, 227, 229, 239, 240, 257, 258, 277, 278, 279, 281, 288, 298, 302, 303, 310, 311, 312, 320, 324, 328, 364;CI Disperse Violet 1, 4, 8, 23, 26, 27, 28, 31, 33, 35, 36, 38, 40, 43, 46, 48, 50, 51, 52, 56, 57, 59, 61, 63, 69, 77;CIDisperse Green 9;CI Disperse Brown 1, 2, 4, 9, 13, 19;CI Disperse Blue 3, 7, 9, 14, 16, 19, 20, 24, 26, 27, 35, 43, 44, 54, 55, 56, 58, 60, 62, 64, 71, 72, 73, 75, 79, 81, 82, 83, 87, 91, 92, 93, 94, 95, 96, 102, 106, 108, 112, 113, 115, 118, 120, 122, 125, 128, 130, 139, 141, 142, 143, 146, 148, 149, 153, 154, 158, 165, 167, 171, 173, 174, 176, 181, 183, 185, 186, 187, 189, 197, 198, 200, 201, 205, 207, 211, 214, 224, 225, 257, 259, 267, 268, 270, 284, 285, 287, 288, 291, 293, 295, 297, 301, 315, 330, 333, 359, 360; CI Disperse Black 1, 3, 10, 24, etc.

[0026] Examples of oil-based dyes include CI Solvent Black 3, 7, 27, 29, 34; CI Solvent Yellow 14, 16, 19, 29, 56, 82; CI Solvent Red 1, 3, 8, 18, 24, 27, 43, 51, 72, 73, 132, 218; CI Solvent Violet 3; CI Solvent Blue 2, 5, 11, 70; CI Solvent Green 3, 7; and CI Solvent Orange 2.

[0027] Fluorescent dyes include, for example, CI Disperse Red 362, 364; CI Bat Red 41; CI Disperse Yellow 43, 82, 184, 232, and the like.

[0028] Examples of reactive dyes include yellow dyes such as CI Reactive Yellow 2, 3, 18, 81, 84, 85, 95, 99, and 102; orange dyes such as CI Reactive Orange 5, 9, 12, 13, 35, 45, and 99; brown dyes such as CI Reactive Brown 2, 8, 9, 17, and 33; and CI Reactive Red 1, 3, 4, 13, 15, 24, 29, 31, 33, 120, 125, 151, 206, 207, 209, 210, 211, 212, 213, 214, 215, 216, 217, 218, 219, 220, 221, 222, 223, 224, 225, 226, 227, 228, 229, 230, 231, 232, 233, 234, 235, 236, 237, 238, 239, 240, 241, 242, 243, 244, 245, 246, 247, 248, 249, 250, 251, 252, 253, 254, 255, 256, 257, 258, 259, 260, 261, 262, 263, 264, 265, 266, 267, 268, 269, 270, 271, 272, 273, 274, red dyes such as CI Reactive Violet 24; blue dyes such as CI Reactive Blue 2, 4, 5, 10, 13, 14, 15, 15:1, 19, 21, 49, 63, 71, 72, 75, 162, 176, 198; green dyes such as CI Reactive Green 5, 8, 19; and black dyes such as CI Reactive Black 1, 8, 23, 39.

[0029] Among these, pigments are preferred as coloring materials. This makes it possible to improve the color development of the recording portion formed using the aqueous ink-jet ink composition. Furthermore, conventionally, when a pigment and inorganic oxide particles coexist in the same aqueous ink-jet ink composition, problems such as a decrease in storage stability and ejection stability of the aqueous ink-jet ink composition were particularly likely to occur. In contrast, the present invention can suitably prevent the occurrence of such problems even when a pigment and inorganic oxide particles coexist in the same aqueous ink-jet ink composition. In other words, when the coloring material is a pigment, the effects of the present invention are more pronounced.

[0030] In particular, when the coloring material is a self-dispersing pigment, the ratio of the pigment to the amount added is high, so that the coloring property is high and the intermittent printing stability is further improved.

[0031] The content of the colorant in the aqueous inkjet ink composition is preferably from 5.0% to 15.0% by mass, more preferably from 5.5% to 14.0% by mass, and even more preferably from 6.0% to 13.0% by mass.

[0032] By containing the coloring material at such a relatively high content, the color development of the recorded portion formed using the aqueous ink-jet ink composition can be made more excellent. In addition, the occurrence of undesired color unevenness in the recorded matter produced using the aqueous ink-jet ink composition can be more effectively prevented. Furthermore, in conventional aqueous ink-jet ink compositions, when the aqueous ink-jet ink composition contains a relatively high content of the coloring material as described above together with inorganic oxide particles, problems such as a decrease in storage stability and ejection stability of the aqueous ink-jet ink composition are particularly likely to occur. In contrast, in the present invention, even when the aqueous ink-jet ink composition contains a relatively high content of the coloring material as described above together with inorganic oxide particles, the occurrence of such problems can be suitably prevented. That is, when the content of the coloring material in the aqueous ink-jet ink composition is within the above range, the effects of the present invention are more significantly exhibited.

[0033] [1-3] Inorganic oxide particles The water-based ink-jet ink composition of the present invention contains inorganic oxide particles. The inorganic oxide particles are dispersed in the dispersion medium by the dispersant, which will be described later in detail.

[0034] Examples of inorganic oxide particles include silica, alumina, titania, zirconia, antimony oxide, tin oxide, tantalum oxide, zinc oxide, cerium oxide, lead oxide, and indium oxide. One or more types selected from these can be used in combination.

[0035] Among these, the inorganic oxide particles are preferably made of a material containing silica.

[0036] This makes it possible to more effectively prevent curling of a recording medium when the water-based ink-jet ink composition is applied to the recording medium for recording.

[0037] When the inorganic oxide particles are composed of a material containing silica, the silica content in the inorganic oxide particles is preferably 90% by mass or more, more preferably 95% by mass or more, and even more preferably 99% by mass or more.

[0038] The average particle size of the inorganic oxide particles is preferably 10 nm or more and 200 nm or less, more preferably 20 nm or more and 150 nm or less, and even more preferably 30 nm or more and 100 nm or less.

[0039] This makes it possible to more effectively suppress curling of a recording medium when the aqueous ink-jet ink composition is applied to a recording medium for recording, and also makes it possible to improve the storage stability, ejection stability, etc. of the aqueous ink-jet ink composition.

[0040] In this specification, unless otherwise specified, the average particle size means the particle size at which the frequency of the particle amount is 50% when calculated cumulatively from the small particle size side in the particle distribution measured by dynamic light scattering, and can be determined, for example, by measurement using a zeta potential / particle size measurement system "ELSZ-1000ZS" (manufactured by Otsuka Electronics Co., Ltd.).

[0041] The content of inorganic oxide particles in the aqueous inkjet ink composition is preferably 0.2% by mass or more and 8.0% by mass or less, more preferably 0.5% by mass or more and 7.0% by mass or less, and even more preferably 1.5% by mass or more and 5.0% by mass or less.

[0042] This makes it possible to more effectively suppress curling of a recording medium when the aqueous ink-jet ink composition is applied to a recording medium for recording, and also makes it possible to improve the storage stability, ejection stability, etc. of the aqueous ink-jet ink composition.

[0043] [1-4] Dispersants When the ink contains inorganic oxide particles, the above-mentioned problem occurs. It is presumed that the inorganic oxide particles precipitate as the volatile components contained in the ink evaporate. In particular, when the ink is dried to a high degree, the redispersibility of the inorganic oxide particles decreases, and even if the inkjet head is cleaned, the ink ejection stability may not be fully restored.

[0044] The water-based ink-jet ink composition of the present invention contains a dispersant, in particular a dispersant that has the function of dispersing inorganic oxide particles in a dispersion medium.

[0045] As the dispersant, a nonionic dispersant or an anionic dispersant can be suitably used.

[0046] Examples of the dispersant include polymer dispersants such as polyvinyl alcohols, styrene-based resins such as styrene-maleic acid resins and styrene-acrylic acid resins, and sulfonates such as naphthalenesulfonic acid condensates. One or a combination of two or more selected from these can be used.

[0047] When the dispersant is a polymer dispersant, the effect of allowing the inorganic oxide particles and the dispersant to coexist is more pronounced, and the storage stability, ejection stability, and the like of the aqueous inkjet ink composition can be improved.

[0048] Among them, the dispersant is preferably at least one selected from polyvinyl alcohols and styrene-maleic acid resins.

[0049] This makes it possible to more significantly exhibit the effect of having the inorganic oxide particles and the dispersant coexist, and to further improve the storage stability, ejection stability, and the like of the water-based ink-jet ink composition.

[0050] In this specification, the polymer dispersant refers to a dispersant containing a chemical structure in which a plurality of monomers are bonded. The polymer dispersant may contain a plurality of types of monomer components.

[0051] The weight average molecular weight of the polymer dispersant is preferably from 10,000 to 100,000, more preferably from 30,000 to 90,000, and even more preferably from 40,000 to 80,000.

[0052] This makes it possible to more significantly exhibit the effect of having the inorganic oxide particles and the dispersant coexist, and to further improve the storage stability, ejection stability, and the like of the water-based ink-jet ink composition.

[0053] The content of the dispersant in the aqueous inkjet ink composition is preferably from 0.1% to 6.0% by mass, more preferably from 0.2% to 4.0% by mass, and even more preferably from 0.5% to 2.5% by mass.

[0054] This makes it possible to more effectively suppress curling of a recording medium when the aqueous ink-jet ink composition is applied to a recording medium for recording, and also makes it possible to improve the storage stability, ejection stability, etc. of the aqueous ink-jet ink composition.

[0055] The content of the dispersant per 100 parts by mass of inorganic oxide particles is preferably 20 parts by mass or more and 100 parts by mass or less, more preferably 25 parts by mass or more and 85 parts by mass or less, and even more preferably 30 parts by mass or more and 75 parts by mass or less.

[0056] This makes it possible to more effectively suppress curling of a recording medium when the aqueous ink-jet ink composition is applied to a recording medium for recording, and also makes it possible to improve the storage stability, ejection stability, etc. of the aqueous ink-jet ink composition.

[0057] [1-5]Dispersion medium The water-based inkjet ink composition of the present invention contains a dispersion medium that disperses inorganic oxide particles as dispersoids. The dispersion medium may also function as a solvent that dissolves components other than the inorganic oxide particles. The dispersion medium contains at least water.

[0058] The proportion of water in the entire dispersion medium is preferably 40.0% by mass or more, more preferably 50.0% by mass or more and 95.0% by mass or less, and even more preferably 60.0% by mass or more and 90.0% by mass or less.

[0059] The water content in the aqueous ink-jet ink composition is preferably 67.0% by mass or less, more preferably from 50.0% to 66.5% by mass, and even more preferably from 55.0% to 66.0% by mass.

[0060] This makes it possible to more effectively suppress curling of the recording medium when the aqueous ink-jet ink composition is applied to a recording medium for recording. Furthermore, in conventional aqueous ink-jet ink compositions, particularly aqueous ink-jet ink compositions in which a colorant and inorganic oxide particles coexist, problems such as reduced storage stability and ejection stability of the aqueous ink-jet ink composition have been more pronounced when the water content is relatively low as described above, but the present invention can suitably prevent the occurrence of such problems even when the water content is relatively low as described above. In other words, when the water content in the aqueous ink-jet ink composition is within the above range, the effects of the present invention are more pronounced.

[0061] The dispersion medium constituting the aqueous ink-jet ink composition of the present invention may contain components other than water, such as water-soluble organic solvents such as polyol compounds, glycol ethers, and betaine compounds.

[0062] Examples of the polyol compound include polyol compounds having 2 to 6 carbon atoms in the molecule and optionally having an ether bond in the molecule. Specific examples include 1,2-pentanediol, triethylene glycol, triethylene glycol monomethyl ether, triethylene glycol monobutyl ether, trimethylolpropane, diethylene glycol monobutyl ether, dipropylene glycol monopropyl ether, glycerin, 1,2-hexanediol, 1,2-heptanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2, Examples of the alkyl ether ester include 3-butanediol, 2-methyl-3-phenoxy-1,2-propanediol, 3-(3-methylphenoxy)-1,2-propanediol, 3-hexyloxy-1,2-propanediol, 2-hydroxymethyl-2-phenoxymethyl-1,3-propanediol, 3-methyl-1,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, 2-methyl-2,4-pentanediol, and 3-methyl-1,5-pentanediol.

[0063] The glycol ether is preferably a monoalkyl ether of a glycol selected from, for example, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol, and polyoxyethylene polyoxypropylene glycol. More preferably, triethylene glycol monomethyl ether, triethylene glycol monobutyl ether, dipropylene glycol monopropyl ether, and the like can be mentioned.

[0064] A betaine compound is a compound that has a positive charge and a negative charge at non-adjacent positions in the same molecule, and the positively charged atom is not bound to a dissociable hydrogen atom, and the molecule as a whole does not have a charge.Preferred betaine compounds are N-alkyl substituted amino acids, more preferably N-trialkyl substituted amino acids.Examples of betaine compounds include trimethylglycine, γ-butyrobetaine, homarine, trigonelline, carnitine, homoserine betaine, valine betaine, lysine betaine, ornithine betaine, alanine betaine, stachydrine, and glutamic acid betaine, and preferably trimethylglycine.

[0065] Furthermore, a pyrrolidone derivative may be used as the water-soluble organic solvent, for example, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, 2-pyrrolidone, N-butyl-2-pyrrolidone, 5-methyl-2-pyrrolidone, etc.

[0066] The content of the dispersion medium in the aqueous inkjet ink composition is preferably from 60.0% to 94.0% by mass, more preferably from 70.0% to 92.0% by mass, and even more preferably from 80.0% to 90.0% by mass.

[0067] This makes it possible to more effectively suppress curling of a recording medium when the aqueous ink-jet ink composition is applied to a recording medium for recording, and also makes it possible to improve the storage stability, ejection stability, etc. of the aqueous ink-jet ink composition.

[0068] [1-6] Other ingredients The aqueous ink-jet ink composition of the present invention may contain components other than those described above. Hereinafter, in this section, such components are also referred to as "other components".

[0069] Examples of other components include pH adjusters, surfactants, chelating agents, preservatives, antifungal agents, rust inhibitors, antioxidants, ultraviolet absorbers, oxygen absorbers, penetrating agents, etc., and one or more selected from these may be used in combination.

[0070] Furthermore, the water-based inkjet ink composition of the present invention may contain, as other components, a dispersant having a function of dispersing inorganic oxide particles in a dispersion medium, and a dispersant different from the dispersant, more specifically, a dispersant that does not have a function of dispersing inorganic oxide particles in a dispersion medium, but has a function of dispersing components other than inorganic oxide particles, such as pigments, in the dispersion medium. In the following description, a dispersant having a function of dispersing inorganic oxide particles in a dispersion medium is also referred to as a "first dispersant", and a dispersant having a function of dispersing components other than inorganic oxide particles in a dispersion medium is also referred to as a "second dispersant".

[0071] The second dispersant has a different chemical structure from the first dispersant described above. Examples of the second dispersant include acrylic resin, styrene acrylic resin, urethane resin, etc., and one or more of these may be used in combination.

[0072] When the aqueous ink-jet ink composition of the present invention contains a second dispersant together with a first dispersant, when the content of the first dispersant in the aqueous ink-jet ink composition is X1 [mass %] and the content of the second dispersant in the aqueous ink-jet ink composition is X2 [mass %], it is preferable that the relationship of 0.1≦X2 / X1≦1.5 is satisfied, and it is more preferable that the relationship of 0.2≦X2 / X1≦1.0 is satisfied.

[0073] The content of other components in the aqueous ink-jet ink composition is preferably 10.0% by mass or less, more preferably 7.0% by mass or less, and even more preferably 5.0% by mass or less.

[0074] [1-7] Other conditions The viscosity of the aqueous ink-jet ink composition of the present invention at 25° C. is2 / s or more 10mm 2 / s or less is preferable, and 3 mm 2 / s or more 8mm 2 / s or less is preferable, and 4 mm 2 / s or more 6mm 2 It is even more preferable that the ratio is equal to or less than 1 / s. This provides the water-based ink-jet ink composition with better ejection stability when subjected to an ink-jet method.

[0075] The viscosity can be measured at 20° C. using a Cannon-Fenske reverse flow viscometer (for example, automatic viscosity measuring device VMC-552 manufactured by Rigo Co., Ltd.).

[0076] [2] Ink composition set Next, the ink composition set according to the present invention will be described.

[0077] The ink composition set according to the present invention includes a plurality of ink compositions, at least one of which is the above-mentioned water-based inkjet ink composition according to the present invention.

[0078] At least one of the ink compositions constituting the ink composition set according to the present invention may be the aqueous ink-jet ink composition of the present invention described above, and the ink composition set according to the present invention may include an ink composition other than the aqueous ink-jet ink composition of the present invention described above. Hereinafter, such an ink composition may be referred to as "other ink composition". Examples of other ink compositions include non-aqueous ink compositions, ink compositions that are applied to a recording medium by a method other than the ink-jet method, and ink compositions that do not contain inorganic oxide particles.

[0079] In particular, the ink composition set according to the present invention preferably comprises a plurality of types of water-based ink-jet ink compositions according to the present invention, and it is more preferable that all of the constituent ink compositions are water-based ink-jet ink compositions according to the present invention.

[0080] The ink composition set according to the present invention preferably includes three water-based inkjet ink compositions corresponding to the three primary colors, i.e., cyan, magenta, and yellow. The three primary colors may be further divided according to their color densities. For example, the ink composition set may include light cyan, light magenta, and light yellow in addition to cyan, magenta, and yellow.

[0081] The ink composition set according to the present invention may also include an achromatic ink, more specifically, a black ink.

[0082] [3] Recording method Next, the recording method of the present invention will be described.

[0083] The recording method of the present invention is a method in which recording is performed by ejecting the above-mentioned water-based ink-jet ink composition of the present invention from an ink-jet head.

[0084] This makes it possible to effectively prevent curling of the recording medium to which the aqueous ink-jet ink composition has been applied.

[0085] Hereinafter, a method will be described which includes an aqueous ink-jet ink composition application step of ejecting the aqueous ink-jet ink composition of the present invention from an ink-jet head and applying it to a recording medium, and a drying step of drying the recording medium to which the aqueous ink-jet ink composition has been applied.

[0086] [3-1] Recording media In the recording method of the present invention, a recording medium containing cellulose fibers, such as plain paper, can be suitably used as the recording medium.

[0087]

[0023] Such recording media are advantageous in that they are relatively inexpensive, easily available, and can provide suitable ink permeability, etc., but on the other hand, they have a problem in that they are prone to curling when an aqueous ink-jet ink composition is applied to them. In contrast, in the present invention, even when such a recording medium is used, the occurrence of curling can be sufficiently suppressed.

[0088] [3-2] Water-based inkjet ink composition application process In the water-based ink-jet ink composition application step, the water-based ink-jet ink composition of the present invention is ejected by an ink-jet method and applied to a recording medium.

[0089] In this step, for example, solid printing may be performed so that the amount of the aqueous ink-jet ink composition applied to each portion of the recording medium is uniform, or the amount applied may vary from portion to portion of the recording medium. Also, there may be portions on the recording medium to which the aqueous ink-jet ink composition is not applied.

[0090] As the inkjet method, the method described above in [1-1] can be used. In this step, multiple types of water-based ink-jet ink compositions may be used.

[0091] [3-3] Drying process This embodiment includes a drying step of drying the recording medium to which the water-based inkjet ink composition has been applied. This makes it possible to improve the productivity of recorded matter.

[0092] This step may be carried out under any conditions as long as it is possible to remove at least a portion of the volatile liquid components, particularly water, contained in the aqueous inkjet ink composition applied to the recording medium. Examples of the method include drying by heat treatment, drying by placing in a reduced pressure environment, drying by spraying a dry gas, and natural drying. One or a combination of two or more methods selected from these may be used in this step.

[0093] When a heat treatment is performed in this step, the surface temperature of the recording medium to which the aqueous inkjet ink composition is applied in this step is preferably from 40° C. to 95° C., more preferably from 45° C. to 90° C., and even more preferably from 50° C. to 80° C.

[0094] This makes it possible to more efficiently dry the recording medium to which the aqueous ink-jet ink composition has been applied while more effectively preventing undesired alteration, deterioration, etc. of the recording medium, thereby improving the productivity of the recorded matter. In addition, this is also preferable from the viewpoint of energy saving, since it makes it possible to prevent the energy required for the heating treatment from increasing more than necessary.

[0095] When heat treatment is performed in this step, the treatment time for the heat treatment is preferably from 5 seconds to 120 seconds, more preferably from 10 seconds to 90 seconds, and even more preferably from 20 seconds to 60 seconds.

[0096] This makes it possible to more efficiently dry the recording medium to which the aqueous ink-jet ink composition has been applied while more effectively preventing undesired alteration, deterioration, etc. of the recording medium, thereby improving the productivity of the recorded matter. In addition, this is also preferable from the viewpoint of energy saving, since it makes it possible to prevent the energy required for the heating treatment from increasing more than necessary.

[0097] This step may be carried out simultaneously with the above-mentioned aqueous ink-jet ink composition application step. For example, a print pattern may be formed with the aqueous ink-jet ink composition at a predetermined portion of the recording medium, while a volatile liquid such as water contained in the aqueous ink-jet ink composition applied at another portion of the recording medium may be removed. More specifically, for example, the aqueous ink-jet ink composition application step may be carried out while heating the recording medium, whereby the aqueous ink-jet ink composition application step and the drying step can be suitably carried out simultaneously.

[0098] [3-4] Other processes The recording method of the present invention may further include other steps in addition to the steps described above, for example.

[0099] For example, the recording method of the present invention may further include a step of depositing an ink composition other than the water-based ink-jet ink composition of the present invention onto a recording medium.

[0100] When such a step is carried out, the step may be carried out, for example, before the step of applying the water-based ink-jet ink composition, or may be carried out after the step of applying the water-based ink-jet ink composition.

[0101] [4] Recorded material A recorded matter can be obtained by the above-described recording method of the present invention.

[0102] The recorded matter according to the present invention has colored parts formed with a coloring material, and is suitably prevented from curling.

[0103] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these. EXAMPLES

[0104] Next, specific examples of the present invention will be described. [5] Preparation of Water-Based Inkjet Ink Composition Example 1 First, an aqueous silica dispersion (Cataloid SI-45P, manufactured by JGC Catalysts and Chemicals) was dried to obtain silica particles, which are inorganic oxide particles.

[0105] Next, a vinyl alcohol resin (Nichigo G-Polymer AZF8035W, manufactured by Mitsubishi Chemical Corporation) as a dispersant and the above silica particles were mixed in a mass ratio of 1.0:3.0, and the mixture was diluted with water so that the concentration of the silica particles was 20 mass%.

[0106] Zirconia beads having a diameter of 0.5 mm were added to the mixture containing the silica particles and dispersant obtained as described above, and the mixture was sealed, and then dispersed for 10 hours in a beads disperser to obtain an inorganic oxide particle dispersion liquid.

[0107] An aqueous ink-jet ink composition was prepared by mixing the inorganic oxide particle dispersion obtained as described above, CAB-O-JET300 (manufactured by Cabot Corporation) containing a self-dispersing pigment, triethylene glycol monobutyl ether, triethylene glycol monomethyl ether, glycerin, triethylene glycol, trimethylglycine, Olfin E1010 (manufactured by Nissin Chemical Industry Co., Ltd.) as a surfactant, Surfynol 104 (manufactured by Nissin Chemical Industry Co., Ltd.) as a surfactant, and water in a predetermined ratio.

[0108] (Examples 2 to 8) A water-based ink-jet ink composition was prepared in the same manner as in Example 1, except that the types and amounts of components used in the preparation of the water-based ink-jet ink composition were changed to obtain the composition shown in FIG. 1.

[0109] Example 9 First, Mitsubishi carbon black (for ink, manufactured by Mitsubishi Chemical Corporation) as a pigment that is not a self-dispersing pigment and styrene acrylic acid resin as a resin dispersant were mixed in water at a solid mass ratio of 7:1, and the mixture was dispersed for 5 hours using a bead disperser to obtain a pigment dispersion.

[0110] Thereafter, the pigment dispersion obtained as described above, an inorganic oxide particle dispersion prepared in the same manner as described in Example 1, triethylene glycol monobutyl ether, triethylene glycol monomethyl ether, glycerin, triethylene glycol, trimethylglycine, Olfin E1010 (manufactured by Nissin Chemical Industry Co., Ltd.) as a surfactant, Surfynol 104 (manufactured by Nissin Chemical Industry Co., Ltd.) as a surfactant, and water were mixed in a predetermined ratio to prepare a water-based inkjet ink composition.

[0111] (Examples 10 to 12) A water-based ink-jet ink composition was prepared in the same manner as in Example 9, except that the types and amounts of components used in the preparation of the water-based ink-jet ink composition were changed to obtain the composition shown in FIG. 1.

[0112] (Comparative Examples 1 to 4) A water-based ink-jet ink composition was prepared in the same manner as in Example 1, except that the types and amounts of components used in the preparation of the water-based ink-jet ink composition were changed to obtain the composition shown in FIG. 1.

[0113] The conditions for the aqueous inkjet ink compositions prepared in the above-mentioned Examples and Comparative Examples are summarized in Figure 1. The items shown in Figure 1 are as follows: the solid content of CAB-O-JET300 (manufactured by Cabot Corporation) is the "self-dispersing pigment", Mitsubishi Carbon Black (for ink, manufactured by Mitsubishi Chemical Corporation) is the "non-self-dispersing pigment", the solid content of Cataloid SI-45P (manufactured by JGC Catalysts and Chemicals) is the "silica", and a vinyl alcohol-based resin (Nichigo G-Polymer) as a dispersant is the "non-self-dispersing pigment". AZF8035W, manufactured by Mitsubishi Chemical Corporation) as "AZF8035W", the solid content of styrene maleic acid resin (DISPERBYK-2012, manufactured by BYK) as a dispersant as "D2012", naphthalene sulfonic acid condensate (non-resin, Demol N, manufactured by Kao Corporation) as a dispersant as "Demol N", styrene acrylic acid resin as "pigment dispersant", triethylene glycol monobutyl ether as "BTG", triethylene glycol monomethyl ether as "MTG", glycerin as "GL", triethylene glycol as "TEG", trimethylglycine as "TMG", Olfine E1010 (manufactured by Nissin Chemical Industry Co., Ltd.) as a surfactant as "Olfine E1010", and Surfynol 104 (manufactured by Nissin Chemical Industry Co., Ltd.) as a surfactant as "Surfynol 104".

[0114] The unit of the content of each component in Figure 1 is mass %. The average particle size of the inorganic oxide particles contained in the water-based inkjet ink composition of each of the Examples was in the range of 30 nm to 100 nm. The viscosity of the water-based inkjet ink composition of each of the Examples and Comparative Examples at 25°C was 2 mm 2 / s or more 10mm 2 The value was within the range of / s.

[0115] [6] Evaluation The water-based ink-jet ink compositions of the Examples and Comparative Examples were evaluated as follows.

[0116] [6-1] Color development The following evaluations were carried out using an inkjet recording apparatus: PX-S7050 (manufactured by Seiko Epson Corporation).

[0117] That is, the water-based inkjet ink compositions of the respective Examples and Comparative Examples were each poured into an ink cartridge for the PX-S7050, and then these ink cartridges were mounted on the PX-S7050.

[0118] Thereafter, it was confirmed that all nozzles were ejecting normally, and then each water-based inkjet ink composition was used to perform solid printing at a print density of 100% on a recording medium, plain paper (P paper, manufactured by Fuji Xerox Co., Ltd.) After that, the print was air-dried overnight in a room at 25°C to obtain a recorded matter.

[0119] For the recorded matter according to each of the Examples and Comparative Examples obtained as described above, the solid printed area was measured by reflection measurement using a colorimeter i1Pro2 (manufactured by X-Rite Corporation), and the OD value in the Lab display system was measured and evaluated according to the following criteria. It can be said that the larger this value, the better the color development by the water-based inkjet ink composition.

[0120] A:OD value is 1.2 or more. B: OD value is 1.1 or more and less than 1.2. C:OD value is less than 1.1.

[0121] [6-2] Storage stability The aqueous ink-jet ink compositions of the Examples and Comparative Examples were poured into predetermined ink packs, and these ink packs were left to stand for 6 days in an environment of 70° C. From the results of measuring the viscosity of each aqueous ink-jet ink composition before and after standing using a reverse flow Cannon-Fenske viscometer, the increase in viscosity of each aqueous ink-jet ink composition before and after standing was determined and evaluated according to the following criteria. It can be said that the smaller this value, the better the storage stability of the aqueous ink-jet ink composition.

[0122] A: Viscosity increase is 0.1mm 2 / s or less. B: Viscosity increase is 0.1mm 2 / s or more 0.3mm 2 / s or less. C: Viscosity increase is 0.3 mm 2 / s or more.

[0123] [6-3] Intermittent printing stability The following evaluations were carried out using an inkjet recording apparatus: PX-S7050 (manufactured by Seiko Epson Corporation).

[0124] That is, the water-based inkjet ink compositions of the respective Examples and Comparative Examples were each poured into an ink cartridge for the PX-S7050, and then these ink cartridges were mounted on the PX-S7050.

[0125] After the head was idled for 40 seconds using the PX-S7050 in an environment of 30°C and 20% humidity, the amount of deviation of the ruled lines of the ejected water-based inkjet ink composition, i.e., the deviation from the ruled line width of the normally ejected ink, was measured and evaluated according to the following criteria: The smaller this value, the more excellent the intermittent printing stability of the water-based inkjet ink composition is.

[0126] A: The deviation is less than 30 μm. B: The deviation is 30 μm or more and less than 50 μm. C: The deviation is 50 μm or more.

[0127] [6-4] Curl suppression First, the water-based inkjet ink compositions of the respective Examples and Comparative Examples were poured into dedicated ink cartridges for an inkjet recording apparatus: PX-S7050 (manufactured by Seiko Epson Corporation), and then these ink cartridges were mounted on the PX-S7050.

[0128] Next, a postcard-sized recording medium (P paper, basis weight 64 g / m 2 Solid printing was performed at 100% print density on a paper sheet (88 μm thick, manufactured by Fuji Xerox Co., Ltd.).

[0129] After printing, the recording medium was left face down, and the angle between the point where the recording medium was placed on the floor and the edge of the paper was measured and evaluated according to the following criteria. The smaller this angle, the more effectively curling of the recording medium was suppressed.

[0130] A: The maximum curl angle is less than 90°. B: The maximum curl angle is greater than or equal to 90° and less than 110°. C: Maximum curl angle is 110° or more.

[0131] [6-5] Clogging recovery First, the water-based inkjet ink compositions of the respective Examples and Comparative Examples were poured into dedicated ink cartridges for an inkjet recording apparatus: PX-S7050 (manufactured by Seiko Epson Corporation), and then these ink cartridges were mounted on the PX-S7050.

[0132] Next, with the inkjet head removed from the capping position, the PX-S7050 was left in an environment with a temperature of 40°C and a humidity of 20% for 7 days.

[0133] After leaving the nozzles, a cleaning process was performed, and the number of cleanings required to restore all the nozzles was determined and evaluated according to the following criteria. The smaller this number, the better the ability to restore clogging.

[0134] A: The number of cleanings required to restore all nozzles is less than six. B: The number of cleanings required to recover all nozzles is between 6 and 9 times. C: All nozzles were recovered after 9 or more cleanings, or no nozzles were recovered. These results are summarized in FIG.

[0135] As is clear from Fig. 2, excellent results were obtained in the present invention. In contrast, satisfactory results were not obtained in the comparative example.

[0136] In addition, water-based ink-jet ink compositions were prepared in the same manner as in the above Examples, except that the content of the colorant in the water-based ink-jet ink composition was changed in various ways within the range of 5.0% by mass or more and 15.0% by mass or less, and evaluations were performed in the same manner as above, and excellent results were obtained as above.

Claims

1. The ink contains a coloring material, inorganic oxide particles, a dispersant, and a dispersion medium containing water, The aqueous ink-jet ink composition, wherein the inorganic oxide particles are dispersed in the dispersion medium by the dispersant.

2. The water-based ink-jet ink composition of claim 1 , wherein the dispersant is a polymeric dispersant.

3. The water-based ink-jet ink composition according to claim 1 or 2, wherein a content of the dispersant per 100 parts by mass of the inorganic oxide particles is 20 parts by mass or more and 100 parts by mass or less.

4. The water-based ink-jet ink composition according to claim 1 or 2, wherein the inorganic oxide particles are made of a material containing silica.

5. The water-based ink-jet ink composition according to claim 1 or 2, wherein the coloring material is a pigment.

6. The water-based ink-jet ink composition of claim 5 , wherein the colorant is a self-dispersed pigment.

7. The water-based ink-jet ink composition according to claim 1 or 2, wherein the content of the coloring material in the water-based ink-jet ink composition is 5.0% by mass or more and 15.0% by mass or less.

8. The water-based ink-jet ink composition according to claim 1 or 2, wherein the water content in the water-based ink-jet ink composition is 67.0% by mass or less.

9. A recording method comprising discharging the water-based ink-jet ink composition according to claim 1 or 2 from an ink-jet head to perform recording.

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