JP2017190430A - Inkjet ink, inkjet recording method and inkjet recording device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aqueous inkjet ink that does not excessively wet and spread when discharged to a poorly absorbable recording medium from an inkjet head and suppresses image blurring, and has excellent dryability and image properties.SOLUTION: An inkjet ink contains at least water, a resin component, a colorant, and an associative thickener, the associative thickener being a urethane modified polyether polymer.SELECTED DRAWING: None

Description

  The present invention relates to an inkjet ink. The present invention also relates to an ink jet recording method using the ink jet ink. The present invention also relates to an ink jet recording apparatus including the ink jet ink.

  Inkjet printers employing the inkjet printing method are widely used as digital printing output machines. Conventionally, when printing on a recording medium that hardly absorbs an ink such as polyvinyl chloride or polyethylene terephthalate (PET) using an ink jet printer (hardly-absorbing recording medium), the surface of the recording medium is dissolved. So-called solvent ink that fixes a coloring material and a binder resin, and UV curable ink that cures ink deposited on a recording medium with UV light and adheres to the recording medium are used.

  However, development of water-based inkjet ink suitable for printing on a hardly-absorbable recording medium has been promoted from the viewpoint of safety with respect to recent ink and reduction of environmental burden. In printing on a hardly absorbent recording medium using a water-based inkjet ink, image quality, drying properties, image strength, and the like equivalent to those of a solvent ink and a UV curable ink are required. In response to such demands, water-based inkjet inks containing water, resin components (particularly resin fine particles), and colorants have been developed.

  In order to improve the characteristics of such an aqueous inkjet ink, it is known to add a thickener. For example, Patent Document 1 discloses an aqueous inkjet ink containing water, a coloring material, a water-soluble thickener, and resin particles. According to such an aqueous inkjet ink, the occurrence of curling of a recording medium is disclosed. It is described that the ink storage stability is good, the ink ejection stability is good, and the occurrence of image deformation can be suppressed.

JP 2010-65205 A

  As a result of intensive studies by the present inventors, when a water-soluble thickener is used in an aqueous inkjet ink as described in Patent Document 1, a recording medium is ejected from an inkjet head onto a hardly absorbent recording medium. It was found that the ink was excessively wet and spread on the surface, and as a result, image bleeding occurred. Moreover, it turned out that drying property and image characteristics may be insufficient compared with the water-based inkjet ink which does not add a thickener.

  Accordingly, the present invention provides a water-based inkjet ink in which excessive wetting and spreading when ejected from an inkjet head onto a hardly absorbent recording medium is suppressed, image bleeding is suppressed, and drying properties and image characteristics are good. For the purpose.

  The inkjet ink of the present invention is an inkjet ink containing at least water, a resin component, a colorant, and an associative thickener, and the associative thickener is a urethane-modified polyether polymer.

In the ink-jet ink of the present invention, when the viscosity at 25 ° C. is V1, the viscosity at 40 ° C. is V2, and the viscosity at 40 ° C. when reduced to 10% by weight is V3, it is preferable that the following equation holds.
5.0 mPa · s ≦ V1 ≦ 20.0 mPa · s
V1 / V2 ≧ 1.6
V3 / V2 ≧ 1.3

  In the inkjet ink of the present invention, the resin component is preferably resin fine particles.

  In the inkjet ink of the present invention, the colorant is preferably a pigment.

  The inkjet ink of the present invention preferably further contains an organic solvent.

  The inkjet ink of the present invention preferably further contains a surfactant.

  In the inkjet ink of the present invention, the solid content concentration is preferably 20.0% by weight or less.

  The present invention is also an ink jet recording method comprising a step of heating a hardly absorbable recording medium and a step of ejecting ink jet ink to the heated hardly absorbable recording medium, wherein the ink jet ink is the above This is an inkjet recording method which is an inkjet ink.

  The present invention also includes a transport unit that transports the hardly absorbent recording medium, a heating unit that heats the transported hardly absorbent recording medium, and a discharge unit that ejects inkjet ink onto the heated hardly absorbent recording medium. An ink jet recording apparatus comprising: an ink containing portion that contains the ink jet ink and supplies the ink jet ink to the discharge portion, wherein the ink jet ink is the ink jet ink described above.

  According to the present invention, there is provided an aqueous inkjet ink in which excessive wetting and spreading when being ejected from an inkjet head onto a hardly absorbent recording medium is suppressed, image bleeding is suppressed, and drying properties and image characteristics are good. Is done.

1 is a conceptual diagram of an embodiment of an inkjet recording apparatus of the present invention.

  The inkjet ink of the present invention is an inkjet ink containing at least water, a resin component, a colorant, and an associative thickener, and the associative thickener is a urethane-modified polyether polymer. The inkjet ink of the present invention may further contain an organic solvent, a surfactant and the like. Hereinafter, each component of the inkjet ink of the present invention will be described.

(water)
<Type>
The inkjet ink of the present invention contains water as an essential component. The water is preferably ion-exchanged water, ultrafiltered water, reverse osmosis water, distilled water, or ultrapure water, more preferably ion-exchanged water, from the viewpoint of preventing impurities from being mixed.

<Addition amount>
The water content in the ink is preferably 30% by weight or more, and more preferably 50% by weight or more. On the other hand, 95 weight% or less is preferable and 90 weight% or less is more preferable.

(Resin component)
<Type>
The ink-jet ink of the present invention contains a resin component as an essential component. The resin component is a binder component that improves the fixing property to the recording medium and the coating film resistance. The resin component may be a water-soluble resin or a hydrophobic resin. Therefore, it may be dissolved in the ink or may be dispersed without being dissolved. A resin component can be used individually by 1 type or in combination of 2 or more types by arbitrary ratios.

  The resin component is preferably in the form of resin fine particles in the ink. When resin fine particles are used as the resin component, a relatively high molecular weight hydrophobic resin can be used, so that it is possible to increase image scratch resistance and water resistance.

  Examples of the resin constituting the resin fine particles include urethane resin, polyester resin, acrylic resin, vinyl acetate resin, polyethylene resin, polypropylene resin, fluoroolefin resin, butadiene resin, styrene resin, styrene-butadiene resin, styrene-acrylic resin, A vinyl chloride resin, an acryl-silicone resin, a fluororesin, etc. are mentioned.

  The resin fine particles do not need to be composed of one kind of resin, and may be composed of two or more kinds of resins. For example, different types of monomers are emulsified in core-shell type resin particles with different resin compositions in the core and shell and acrylic particles (seed particles) prepared in advance to control the particle size. Fine particles obtained by polymerization can be used. Furthermore, hybrid resin fine particles obtained by chemically combining resin fine particles composed of different resins, such as fine particles made of acrylic resin and fine particles made of urethane resin, can be used.

<Particle size>
The particle diameter of the resin fine particles is, for example, 30 nm to 200 nm, preferably 40 nm to 150 nm, and more preferably 50 nm to 100 nm. If the thickness is less than 30 nm, there is a possibility that the storage stability of the ink is deteriorated. If it exceeds 200 nm, coalescence of the resin fine particles due to heating becomes non-uniform, and there is a possibility that problems such as a decrease in transparency of the image may occur.

<Glass transition temperature>
The glass transition temperature of the resin component is preferably at least equal to or lower than the heating temperature after adhesion of the recording medium, and more preferably sufficiently lower than the heating temperature. For example, when the heating temperature is 60 ° C, the glass transition temperature of the resin component is preferably in the range of -20 ° C to 50 ° C, more preferably in the range of 0 ° C to 40 ° C. The lower the glass transition temperature, the better the film-forming property. However, if the glass transition temperature is too low, not only a sufficient image strength cannot be obtained, but an image offset due to winding of the recording medium tends to occur.

<Addition amount>
The amount of the resin component added (the total amount in the case where there are a plurality of types of resins) is preferably from 1.0% by weight to 20.0% by weight as the solid content, and from 2.5% by weight to 17.5% by weight. Is preferred, and more preferably 5.0% by weight or more and 15.0% by weight. If it is less than 1.0% by weight, the effect as a binder cannot be obtained, and there is a possibility that problems such as a decrease in scratching properties may occur. If it exceeds 20.0% by weight, an increase in the viscosity of the ink with respect to the loss on drying becomes excessively large, which may cause a problem such as a decrease in ejection stability. In addition, storage stability may be reduced.

(Coloring material)
<Type>
The ink-jet ink of the present invention contains a colorant as an essential component. Examples of the colorant include dyes and pigments. A coloring material can be used individually by 1 type or in combination of 2 or more types by arbitrary ratios.

  As the dye, for example, various dyes that are known to be usable for water-based inkjet inks can be used. Examples thereof include direct dyes, acid dyes, food dyes, basic dyes, and reactive dyes. , Disperse dyes, vat dyes and the like.

  More specifically, examples of the cyan dye include C.I. I. Acid Blue 1,7,9,15,22,23,25,27,29,40,41,43,45,54,59,60,62,72,74,78,80,82,83,90, 92, 93, 100, 102, 103, 104, 112, 113, 117, 120, 126, 127, 129, 130, 131, 138, 140, 142, 143, 151, 154, 158, 161, 166, 167, 168, 170, 171, 182, 183, 184, 187, 192, 199, 203, 204, 205, 229, 234, 236, 249, C.I. I. Direct Blue 1, 2, 6, 15, 22, 25, 41, 71, 76, 77, 78, 80, 86, 87, 90, 98, 106, 108, 120, 123, 158, 160, 163, 165 168, 192, 193, 194, 195, 196, 199, 200, 201, 202, 203, 207, 225, 226, 236, 237, 246, 248, 249, C.I. I. Reactive Blue 1, 2, 3, 4, 5, 7, 8, 9, 13, 14, 15, 17, 18, 19, 20, 21, 25, 26, 27, 28, 29, 31, 32, 33, 34, 37, 38, 39, 40, 41, 43, 44, 46, C.I. I. Food Blue 1, 2, C.I. I. Basic Blue 9, 25, 28, 29, 44 etc. are mentioned.

  Examples of the magenta dye include C.I. I. Acid Red 1,6,8,9,13,14,18,26,27,32,35,37,42,51,52,57,75,77,80,82,85,87,88,89, 92, 94, 97, 106, 111, 114, 115, 117, 118, 119, 129, 130, 131, 133, 134, 138, 143, 145, 154, 155, 158, 168, 180, 183, 184 186, 194, 198, 209, 211, 215, 219, 249, 252, 254, 262, 265, 274, 282, 289, 303, 317, 320, 321, 322, C.I. I. Direct Red 1, 2, 4, 9, 11, 13, 17, 20, 23, 24, 28, 31, 33, 37, 39, 44, 46, 62, 63, 75, 79, 80, 81, 83, 84, 89, 95, 99, 113, 197, 201, 218, 220, 224, 225, 226, 227, 228, 229, 230, 231, C.I. I. Reactive Red 1, 2, 3, 4, 5, 6, 7, 8, 11, 12, 13, 15, 16, 17, 19, 20, 21, 22, 23, 24, 28, 29, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 45, 46, 49, 50, 58, 59, 63, 64, C.I. I. Food Red 7, 9, 14 etc. are mentioned.

  Examples of yellow dyes include C.I. I. Acid Yellow 1,3,11,17,19,23,25,29,36,38,40,42,44,49,59,61,70,72,75,76,78,79,98,99, 110, 111, 127, 131, 135, 142, 162, 164, 165, C.I. I. Direct Yellow 1,8,11,12,24,26,27,33,39,44,50,58,85,86,87,88,89,98,110,132,142,144, Reactive Yellow 1, 2, 3, 4, 6, 7, 11, 12, 13, 14, 15, 16, 17, 18, 22, 23, 24, 25, 26, 27, 37, 42, C.I. I. Food Yellow 3, 4 etc. are mentioned.

  Examples of the black dye include C.I. I. Direct Black 1, 7, 19, 32, 51, 71, 108, 146, 154, 166 and the like.

  Examples of dyes other than cyan, magenta, yellow, and black include C.I. I. Acid Green 7, 12, 25, 27, 35, 36, 40, 43, 44, 65, 79, C.I. I. Direct Green 1, 6, 8, 26, 28, 30, 31, 37, 59, 63, 64, C.I. I. Reactive Green 6, 7, C.I. I. Direct Violet 2, 48, 63, 90, C.I. I. Reactive Violet 1, 5, 9, 10 etc. are mentioned.

  As the pigment, either an inorganic pigment or an organic pigment can be used. Examples of inorganic pigments include titanium oxide, zinc white, zinc sulfide, white lead, calcium carbonate, precipitated barium sulfate, white carbon, alumina white, kaolin clay, talc, bentonite, black iron oxide, cadmium red, red rose, and molybdenum. Red, molybdate orange, chrome vermilion, yellow lead, cadmium yellow, yellow iron oxide, titanium yellow, chromium oxide, viridian, titanium cobalt green, cobalt green, cobalt chrome green, Victoria green, ultramarine, bituminous, cobalt blue, cerulean Examples include blue, cobalt silica blue, cobalt zinc silica blue, manganese violet, and cobalt violet.

  Examples of organic pigments include azo pigments, phthalocyanine pigments, anthraquinone pigments, quinacridone pigments, isoindolinone pigments, quinophthalone pigments, dye lake pigments, and fluorescent pigments.

  More specifically, examples of cyan pigments include C.I. I. Pigment Blue 1, 2, 3, 15: 1, 15: 3, 15: 4, 15: 6, 16, 21, 22, 60, 64, and the like.

  Examples of magenta pigments include C.I. I. Pigment Red 5, 7, 9, 12, 31, 48, 49, 52, 53, 57, 97, 112, 120, 122, 146, 147, 149, 150, 168, 170, 177, 178, 179, 184 188, 202, 206, 207, 209, 238, 242, 254, 255, 264, 269, 282, C.I. I. Pigment Violet 19, 23, 29, 30, 32, 36, 37, 38, 40, 50 and the like.

  Examples of the yellow pigment include C.I. I. Pigment Yellow 1, 2, 3, 12, 13, 14, 16, 17, 20, 24, 74, 83, 86, 93, 94, 95, 109, 110, 117, 120, 125, 128, 129, 137, 138, 139, 147, 148, 150, 151, 154, 155, 166, 168, 180, 185, 213 and the like.

Examples of the black pigment include carbon black produced by a furnace method or a channel method. In particular, these carbon blacks have a primary particle diameter of 11 to 40 nm, a specific surface area by the BET method of 50 to 400 m ² / g, a volatile content of 0.5 to 10%, a pH value of 2 to 10 and the like. Those having the following are preferred. Examples of commercially available products having such characteristics include No. 33, 40, 45, 52, 900, 2200B, 2300, MA7, MA8, MCF88 (above, manufactured by Mitsubishi Chemical Co., Ltd.), RAVEN 1255 (produced by Colombian Carbon), REGA330R, 400R, 660R, MOGUL L, ELFTEX415 (above, NIPEX90, NIPEX150T, NIPEX160IQ, NIPEX170IQ, NIPEX75, Printex85, Printex95, Printex90, Printex35, PrintexU (above, manufactured by Evonik Degussa).

  Examples of pigments other than cyan, magenta, yellow, and black include C.I. I. Pigment Green 7, 10, 36, C.I. I. Pigment Brown 3, 5, 25, 26, C.I. I. Pigment Orange 2, 5, 7, 13, 14, 15, 16, 24, 34, 36, 38, 40, 43, 62, 63, 64, 71 and the like.

  When these pigments are used, it is preferable to uniformly disperse them in the ink in order to maintain long-term ink stability. As a method for dispersing the pigment, there are a method in which the pigment is surface-modified by oxidation treatment or the like, the pigment is self-dispersed without a dispersant, and a method in which the pigment is dispersed using a surfactant or a resin as a dispersant. In order to obtain a more stable inkjet ink, it is preferable to disperse the pigment by self-dispersing the pigment or using a resin as a dispersant.

  The inkjet ink of the present invention may be used in a single color, but it can also be used as an ink set in which a plurality of colors are combined according to the application. The combination is not particularly limited, but a full color image can be obtained by using three colors of cyan, magenta, and yellow. In addition, by adding black ink, the blackness can be improved and the visibility of characters and the like can be improved. Furthermore, color reproducibility can be improved by adding colors such as orange and green. When printing on a print medium other than white, a clear image can be obtained by using white ink together.

  When the pigment is used in the inkjet ink of the present invention in a combination of cyan, magenta, and yellow as a colorant, C.I. I. Pigment Blue 15: 3, 15: 4, C.I. I. Pigment Red 122, 202, 209, 269, C.I. I. Pigment Violet 19, C.I. I. By using a pigment selected from Pigment Yellow 74, 120, 150, 155, and 185 in combination, high color reproducibility can be obtained.

  As the colorant, a pigment is preferable from the viewpoints of light resistance and weather resistance of an image.

<Addition amount>
The added amount of the coloring material (the total amount when there are a plurality of coloring materials) is, for example, 0.1 wt% or more and 20.0 wt% or less, and 1.0 wt% or more and 15. 0 wt% or less is preferable, and 2.0 wt% or more and 10.0 wt% or less is more preferable.

(Associative thickener)
<Type>
The inkjet ink of the present invention contains an associative thickener as an essential component. And, as the associative thickener, urethane-modified polyether polymer is used (hereinafter, urethane-modified polyether polymer used as associative thickener is referred to as “urethane-modified polyether-based associative thickener”. Also called). The associative thickener is a thickener that has a hydrophobic part and a hydrophilic part, and that causes the molecules to associate with each other by hydrophobic interaction in an aqueous medium to increase the viscosity of the system. Urethane-modified polyether-based associative thickeners can be used singly or in combination of two or more in any ratio. Examples of the urethane-modified polyether-based associative thickener include compounds represented by the following general formula (1).

In formula (1), R ¹ and R ² each represent an aliphatic hydrocarbon group or an aromatic hydrocarbon group, and m 1 and n 1 each represent an integer of 1 or more.

  Such a urethane-modified polyether-based associative thickener can be produced according to a known method, and is also available as a commercial product. Examples of commercially available products include SN thickeners 603, 607, 612, 612NC, 625N, A803, A804, A812, A814 (above, manufactured by San Nopco) and Adecanol UH series (produced by Asahi Denka Kogyo Co., Ltd.).

<Addition amount>
The amount of addition of the urethane-modified polyether-based associative thickener (the total amount when there are plural types of urethane-modified polyether-based associative thickeners) is, for example, 0.01 wt% or more as a solid content. 0.000% by weight or less, preferably 0.05% by weight or more and 1.00% by weight or less, and more preferably 0.10% by weight or more and 0.50% by weight or less. If it is less than 0.01% by weight, the effect of adjusting the viscosity of the ink may not be sufficiently obtained. On the other hand, when the content exceeds 2.00% by weight, not only the viscosity becomes too high, but also the influence of the temperature dependency of the viscosity and the increase in the viscosity when the weight loss is reduced may become too great. In addition, there is a risk that problems such as a decrease in the transparency of the image and a decrease in the storage stability of the ink may occur.

(Organic solvent)
The inkjet ink of the present invention may contain an organic solvent as an optional component. By appropriately containing an organic solvent, the ink-jet ink of the present invention can improve dryness, moisture retention, substrate adhesion, and the like. An organic solvent can be used individually by 1 type or in combination of 2 or more types by arbitrary ratios.

<Boiling point>
The boiling point of the organic solvent to be used is preferably 100 ° C. or higher and 290 ° C. or lower from the viewpoint of stably forming an image. If the boiling point of the organic solvent is less than 100 ° C., for example, the solvent of the ink-jet ink may be vaporized from the ink-jet nozzle even in a normal temperature environment, and there is a possibility that the ejection becomes unstable or non-ejection occurs. is there. On the other hand, when the boiling point of the organic solvent exceeds 290 ° C., there is a possibility that problems such as a decrease in image strength due to the ink that has not landed on the recording medium being completely dried and an offset during winding.

<Type>
Among organic solvents, a diol compound (that is, a compound having two OH groups in the chemical structural formula) is preferably used because it has higher moisture retention than a compound containing no or only one OH group. . Examples of the diol compound include ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, dipropylene glycol, 1,2-butanediol, 2,3-butanediol, 2-methyl-2,4-pentanediol, 1, 3-propanediol, 1,2-butanediol, 1,3-butanediol, 3-methyl-1,3-butanediol, 2,2-dimethyl-1,3-propanediol, 2-methyl-1,3 -Propanediol, 1,2-pentanediol, 2,4-pentanediol, 1,5-pentanediol, 2-methyl-2,4-pentanediol, 3-methyl-1,5-pentanediol, 1,6 -Hexanediol, 2-ethyl-1,3-hexanediol, 1,2-hexanediol, , 5-hexanediol, and the like.

  Of the organic solvents, a glycol ether compound is preferably used because it has high permeability to a hardly absorbable recording medium and improves drying properties and adhesion. Examples of the glycol ether compound include ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, diethylene glycol monopentyl ether, diethylene glycol monohexyl ether, triethylene glycol. Monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monopropyl ether, triethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, tetraethylene glycol monobutyl ether, propylene glycol monomethyl ether, pro Lenglycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, dipropylene glycol dimethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monobutyl ether, tripropylene glycol monomethyl ether, tripropylene glycol Monobutyl ether, 3-methoxy-1-butanol, 3-methoxy-3-methylbutanol, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, diethylene glycol diethyl ether, triethylene glycol diethyl ether, tetraethylene glycol die Ether, diethylene glycol methyl ethyl ether, triethylene glycol methyl ethyl ether, tetraethylene glycol methyl ethyl ether, diethylene glycol butyl methyl ether, triethylene glycol butyl methyl ether, tetraethylene glycol butyl methyl ether, propylene glycol dimethyl ether, tripropylene glycol dimethyl ether, etc. Can be mentioned.

  As the organic solvent, a water-soluble nitrogen-containing solvent may be used. Examples of the nitrogen-containing solvent include 2-pyrrolidone, N-methylpyrrolidone, N-ethylpyrrolidone, 3-methyl-2-oxazolidinone, 3-ethyl-2-oxazolidinone, N, N-dimethyl-β-methoxypropionamide. N, N-dimethyl-β-ethoxypropionamide, N, N-dimethyl-β-butoxypropionamide, N, N-dimethyl-β-pentoxypropionamide, N, N-dimethyl-β-hexoxypropionamide N, N-dimethyl-β-heptoxypropionamide, N, N-dimethyl-β-2-ethylhexoxypropionamide, N, N-dimethyl-β-octoxypropionamide, N, N-diethyl-β -Butoxypropionamide, N, N-diethyl-β-pentoxypropionamide, N, N-die Le -β- hexoxyphenyl propionamide, N, N-diethyl -β- heptene Toki Cipro propionamide, N, N-diethyl -β- octoxynol propionamide, and the like.

<Addition amount>
The amount of the organic solvent added (the total amount when there are a plurality of organic solvents) is, for example, 10% to 40% by weight, preferably 12% to 35% by weight, and preferably 15% to 30%. More preferably, it is less than wt%. If the addition amount is less than 10% by weight, there is a possibility that problems such as non-ejection due to drying of ink in the nozzles of the ink jet head and deterioration of image quality due to low wettability with respect to a hardly absorbent recording medium may occur. On the other hand, when the added amount exceeds 40% by weight, there is a possibility that problems such as a decrease in storage stability of the ink may occur.

(Surfactant)
The inkjet ink of the present invention may contain a surfactant as an optional component. The surfactant contributes to improving the wettability with respect to the recording medium by adjusting the surface tension of the ink. From the viewpoint of the storage stability of the ink, the surfactant is preferably a nonionic surfactant.

<Type>
Examples of nonionic surfactants include acetylene glycol surfactants, silicone surfactants, and fluorine surfactants. Surfactant can be used individually by 1 type or in combination of 2 or more types by arbitrary ratios.

  An acetylene glycol-based surfactant is suitably used because it has little foaming and therefore does not require an antifoaming agent and can improve wettability to a recording medium that is difficult to absorb. Examples of the acetylene glycol surfactant include Olphine E1004 and E1010 (manufactured by Nissin Chemical Industry Co., Ltd.). Silicone-based surfactants are known for their high surface tension reducing ability and can be suitably used because they can impart slip properties. Examples of silicone surfactants include Silface 503A and 014 (manufactured by Nissin Chemical Industry Co., Ltd.). A fluorosurfactant is preferably used because it has a high surface tension reducing ability. Examples of the fluorosurfactant include Footgent 250, 212M, 215M, and 251 (manufactured by Neos).

<Addition amount>
The addition amount of the surfactant (the total amount when there are a plurality of surfactants) is, for example, from 0.1% by weight to 5.0% by weight, and from 0.5% by weight to 4.0%. % By weight or less is preferable, and 1.0% by weight or more and 3.0% by weight or less is more preferable. If the amount added is less than 0.1% by weight, the effect of improving the wettability with respect to the hardly-absorbable recording medium may not be sufficiently obtained, and the density uniformity of the solid image may be reduced or the drying property may be reduced. There is a risk of malfunction. On the other hand, when the added amount exceeds 5.0% by weight, there is a possibility that problems such as a decrease in storage stability of the ink may occur. Moreover, there exists a possibility of inhibiting the adhesiveness to a base material.

(Other additives)
The ink-jet ink of the present invention may contain additives such as an antifoaming agent, a thickening agent, a pH adjusting agent, and a preservative in order to obtain an ink having desired characteristics as required in addition to the above components. Good. The addition amount of these additives is, for example, 0.01% by weight or more and 10.0% by weight or less, preferably 0.05% by weight or more and 5.0% by weight or less, and 0.1% by weight or more and 3. 0% by weight or less is more preferable.

(Solid content concentration)
The solid content concentration (solid content ratio) of the inkjet ink of the present invention is preferably 20.0% by weight or less, more preferably 16.0% by weight or less, and even more preferably 12.0% by weight or less. If the solid content concentration exceeds 20.0% by weight, there is a possibility that problems such as a decrease in storage stability of the ink may occur.

  The solid content concentration of the inkjet ink of the present invention can be measured, for example, by the following method. As the measuring device, a heat drying moisture meter (eg, heat drying moisture meter MS-70 (manufactured by A & D)) is used. 0.5 g of ink is dropped within 10 seconds so as to be contained in a glass fiber sheet placed on an aluminum dish, and the solvent is evaporated by setting at 180 ° C. for 1 hour. The ink solid content concentration is calculated from the dropped ink mass before evaporation and the ink solid content mass after evaporation.

  When image recording is performed by an inkjet method using the inkjet ink of the present invention, excessive wetting and spreading when ejected from an inkjet head onto a hardly absorbent recording medium can be suppressed, thereby suppressing image bleeding. be able to. Moreover, color mixing can be suppressed. Also, good drying properties and image characteristics can be obtained.

  In the inkjet ink of the present invention, a urethane-modified polyether-based associative thickener is used, but the urethane-modified polyether-based associative thickener has a hydrophobic portion and a hydrophilic portion. For example, when the resin component is resin fine particles, the hydrophobic portion of the urethane-modified polyether-based associative thickener is adsorbed on the surface of the resin fine particles by hydrophobic interaction. On the other hand, hydrophilic sites are associated by intermolecular forces or hydrogen bonds. As a result, the resin fine particles and the urethane-modified polyether-based associative thickener form a three-dimensional network structure and exhibit a high viscosity. With such a three-dimensional network structure, elasticity is imparted to the ink-jet ink, the generation of minute droplets during ejection can be significantly suppressed, and ejection stability is improved.

  In the ink jet recording system, it is first important how the ink is wetted and spread on the hardly absorbent recording medium. The ink droplets deposited on the recording medium heated in advance during image formation (printing) are instantaneously heated and the viscosity is lowered to spread out. At this time, the solvent contained in the inkjet ink is vaporized by heating. From the viewpoint of high drying properties, it is preferable that this wetting and spreading occurs in a very short time. Therefore, it is preferable that the viscosity decrease when the temperature rises is large. On the other hand, in order to prevent excessive wetting and spreading, it is preferable that the ink viscosity has increased to a reasonably large level when a certain amount of solvent has vaporized. In contrast, urethane-modified polyether-based associative thickeners increase viscosity by adsorbing hydrophobic sites to resin fine particles and association of hydrophilic sites. Inkjet inks containing urethane-modified polyether-based associative thickeners have a large temperature dependence of viscosity (that is, the temperature has increased) because they are desorbed from the resin fine particles and the association of the hydrophilic sites is broken. The degree of viscosity drop is great). Further, the urethane-modified polyether-based associative thickener has a large increase in viscosity when a certain amount of solvent is dried (vaporized). Therefore, when the ink-jet ink of the present invention containing a urethane-modified polyether-based associative thickener is ejected onto a preheated hardly-absorbable recording medium, the ink droplets are greatly reduced in viscosity by heating. As the solvent evaporates, the viscosity increases greatly and the wetting spread stops. For this reason, when image recording is performed by an inkjet method using the inkjet ink of the present invention, excessive wetting and spreading when ejected from an inkjet head onto a hardly absorbent recording medium can be suppressed. It is considered that bleeding can be suppressed. It is also considered that good drying properties and image characteristics can be obtained.

(viscosity)
In order to enjoy the effects of the addition of the urethane-modified polyether-based associative thickener as described above, the ink-jet ink of the present invention has a viscosity at 25 ° C. of V1, a viscosity at 40 ° C. of V2, and a 10% by weight loss on drying. When the viscosity at 40 ° C. is V3, the following formula is preferably satisfied.
5.0 mPa · s ≦ V1 ≦ 20.0 mPa · s
V1 / V2 ≧ 1.6
V3 / V2 ≧ 1.3

<V1>
The viscosity V1 at 25 ° C. of the inkjet ink of the present invention is preferably 5.0 mPa · s or more and 20.0 mPa · s or less, more preferably 6.0 mPa · s or more and 15.0 mPa · s or less, and 7.0 mPa · s or more. 10.0 mPa · s or less is more preferable. When the viscosity V1 is less than 5.0 mPa · s, the discharge stability may be too low. On the other hand, when the viscosity V1 is higher than 20.0 mPa · s, there is a possibility that non-ejection occurs or the image quality is deteriorated.

<V1 / V2>
The ratio (V1 / V2) of the viscosity V1 at 25 ° C. to the viscosity V2 at 40 ° C. of the inkjet ink of the present invention is preferably 1.6 or more. When the ratio V1 / V2 is less than 1.6, the viscosity when the ink is deposited on the heated recording medium is high, the wetting and spreading tends to be insufficient, the drying is insufficient, and the solid image is not good. There is a risk of becoming uniform.

<V3 / V2>
The ratio (V3 / V2) of the viscosity V3 at 40 ° C. when the ink-jet ink of the present invention is 10% by weight reduced to the viscosity V2 at 40 ° C. of the inkjet ink of the present invention is preferably 1.3 or more. . If the ratio V3 / V2 is less than 1.3, the ink having a low viscosity on the recording medium may be wetted and spread more than necessary, which causes problems such as color mixing with adjacent inks and bleeding of fine lines. May occur.

  Note that, by optimizing the type and amount of the urethane-modified polyether-based associative thickener contained in the ink-jet ink, such preferable ranges of V1, ratio V1 / V2, and ratio V3 / V2 are easily satisfied. be able to. Each viscosity can be measured by the following method.

<Measurement method>
As a measuring device, a viscometer (eg, viscometer TVE-25L (manufactured by Toki Sangyo Co., Ltd.)) is used. The cone rotor uses R01, starts measurement at 40.0 rpm, and adopts the value when stabilized. A measured value at 25 ° C. is adopted as the viscosity V1, and a measured value at 40 ° C. is adopted as the viscosity V2. Viscosity V3 at 40 ° C. when 10% by weight of ink-jet ink was dry-dried was measured by placing 10.0 g of ink in an aluminum pan and heating and drying moisture meter (eg, heating and drying moisture meter MS-70 (A & D). The ink is collected when heated to 60 ° C. and the loss on drying reaches 10% by weight, and the viscosity of the ink at 40 ° C. is measured after standing for 24 hours.

(Inkjet recording method)
Another aspect of the present invention is an ink jet recording including a step of heating a hardly absorbent recording medium (heating step) and a step of discharging ink jet ink onto the heated hardly absorbent recording medium (discharging step). It is a method, Comprising: It is an inkjet recording method in which the said inkjet ink is the above-mentioned inkjet ink (inkjet ink of this invention).

<Heating process>
In the heating step, the hardly absorbent recording medium is heated. In the present specification, the “hardly absorbent recording medium” refers to a recording medium having a water absorption amount of 10 mL / m ² or less from the start of contact to 30 msec ^1/2 in the Bristow method. Specifically, the water absorption amount is determined according to the standard No. of “JAPAN TAPPI Paper Pulp Test Method 2000”. 51 It can obtain | require based on the description of "Paper and paperboard-Liquid absorbency test method-Bristow method". Examples of the hard-to-absorb recording medium include art paper, coated paper, matte paper, plastic film, media having a plastic layer formed on a paper substrate, and the like. Examples of the plastic include PET (polyethylene terephthalate), polyvinyl chloride (PVC), polyethylene (PE), polypropylene (PP), polystyrene, polycarbonate, polyurethane, and the like.

  The heating method is not particularly limited and can be performed according to a known method. For example, a method of heating a recording medium by directly contacting a heat source, a method of irradiating the recording medium with infrared rays, microwaves, etc., a temperature of the recording medium A method of blowing wind can be employed. If the temperature of the recording medium is too low, the ink may be insufficiently fixed on the recording medium. Therefore, heating is performed so that the temperature of the recording medium is, for example, 30 ° C. or higher, preferably 40 ° C. or higher. On the other hand, if the temperature of the recording medium is too high, the recording medium may be deformed. Therefore, heating is performed so that the temperature of the recording medium is usually lower than the softening point of the recording medium, preferably 80 ° C. or less, more preferably 60 ° C. or less.

<Discharge process>
Ink jet ink is discharged onto a heated hardly absorbent recording medium. The inkjet ink used in the process is the above-described inkjet ink (the inkjet ink of the present invention). Ink jet ink can be discharged by, for example, a discharge method employed in a known ink jet recording method. Specifically, for example, the ink jet ink droplets can be ejected from the nozzles of the ink jet head using the vibration of the piezoelectric element. By discharging the ink jet ink toward the recording medium, the ink jet ink adheres to the recording medium, and the ink jet ink attached to the recording medium dries, whereby an image can be recorded on the recording medium.

  In the ink jet recording method of the present invention, when ink jet ink is ejected onto a hardly absorbent recording medium, excessive wetting and spreading of the ink on the hardly absorbent recording medium surface can be suppressed, thereby suppressing image bleeding. can do. Moreover, color mixing can be suppressed. Also, good ink drying properties and image characteristics can be obtained.

(Image forming device)
According to another aspect of the present invention, a transport unit that transports a hardly absorbent recording medium, a heating unit that heats the transported hardly absorbent recording medium, and an inkjet ink on the heated hardly absorbent recording medium. An ink jet recording apparatus comprising: an ejecting unit that ejects; and an ink containing unit that accommodates the inkjet ink and supplies the inkjet ink to the ejecting unit, wherein the inkjet ink is the above-described inkjet ink (the inkjet of the present invention) An ink jet recording apparatus.

  Hereinafter, the ink jet recording apparatus of the present invention will be described with reference to FIG. 1 by taking one embodiment as an example. However, the ink jet recording apparatus of the present invention is not limited to the embodiment.

  FIG. 1 is a conceptual diagram of an ink jet recording apparatus 100 according to an embodiment of the present invention. The ink jet recording apparatus 100 includes a supply roller 21, a take-up roller 22, and a transport roller 23 as a transport unit 20 that transports the recording medium 10. The recording medium 10 is unwound from the supply roller 21, passes over the platen 30, is transported by the transport roller 23, and is wound by the winding roller 22. Therefore, in the present embodiment, the conveyance direction of the recording medium 10 is a direction from the supply roller 21 toward the winding roller 22. The recording medium 10 is shown for convenience of explanation, and is not a constituent element of the ink jet recording apparatus 100. As the recording medium 10, a hardly absorbable recording medium is usually used.

  The ink jet recording apparatus 100 includes a heating unit 40. The heating unit 40 serves as a preheater that heats the recording medium 10. The heating unit 40 includes, for example, a contact heating type seat heater, a radiation heater that emits infrared rays and microwaves, a hot air heater, and the like. The heating unit 40 may be installed on either the upper part or the lower part of the recording medium 10 or may be installed on both the upper part and the lower part. The heating unit 40 has heating conditions set so that the temperature of the recording medium 10 is, for example, 30 ° C. or higher and lower than the softening point of the recording medium (preferably 30 to 80 ° C., more preferably 40 to 60 ° C.). Has been.

  The ink jet recording apparatus 100 includes an ejection unit 50 that ejects the ink jet ink 11 onto the recording medium 10. The discharge unit 50 is provided downstream of the heating unit 40 in the conveyance direction of the recording medium 10. The ejection unit 50 includes, for example, an inkjet head that ejects the inkjet ink 11 from a fine nozzle into droplets using the vibration of a piezoelectric element. The ink jet recording apparatus 100 includes an ink storage unit 60, and the ink storage unit 60 is connected to the ejection unit 50. The ink storage unit 60 includes, for example, an ink cartridge. The ink-jet ink 11 before discharge is stored in the ink storage unit 60, and the stored ink-jet ink 11 is supplied to the discharge unit 50 as appropriate. Here, the inkjet ink 11 is the above-described aqueous inkjet ink (the inkjet ink of the present invention).

  The inkjet recording apparatus 100 includes a drying unit 70 that dries the ejected inkjet ink 11. The drying unit 70 is provided downstream of the discharge unit 50 in the conveyance direction of the recording medium 10 and is built in the carriage 71. The drying unit 70 includes, for example, a heater such as a radiation heater that emits infrared rays or microwaves, a warm air heater, or an air blow dryer. The drying unit 70 is set to a drying condition that allows image recording by drying the inkjet ink 11 attached on the recording medium 10. The drying conditions are appropriately selected according to the type and amount of the solvent included in the inkjet ink 11.

  In the ink jet recording apparatus of the present invention, when ink jet ink is ejected onto a hardly absorbent recording medium, excessive wetting and spreading of the ink on the surface of the hardly absorbent recording medium can be suppressed, thereby suppressing image bleeding. can do. Moreover, color mixing can be suppressed. Also, good ink drying properties and image characteristics can be obtained.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not restrict | limited to these Examples. In the following description, “part” represents “part by weight”.

Example 1
35.0 parts of water, 10.0 parts of propylene glycol, 5.0 parts of 2-methyl-1,3-propanediol, 1.0 part of Olfine E1010 (manufactured by Nissin Chemical Industry Co., Ltd.), and 251 (Neos) ) 0.1 part, resin fine particle J-140A (manufactured by Seiko PMC, solid content 41.0% by weight) 19.5 parts, pigment dispersion CAB-O-JET 250C (manufactured by Cabot Specialty Chemicals Inc.) 26.1 parts of solid content 10.0% by weight) and 3.3 parts of urethane-modified polyether-based associative thickener SN thickener 625N (manufactured by San Nopco, solid content 15.0% by weight) in a 25 ° C. environment. After mixing and stirring, the mixture was filtered through a 3 μm cellulose acetate filter to obtain ink 1.

(Example 2)
36.6 parts of water, 10.0 parts of propylene glycol, 5.0 parts of 2-methyl-1,3-propanediol, 1.0 part of Olphine E1010 (manufactured by Nissin Chemical Industry Co., Ltd.), and 251 251 (manufactured by Neos) ) 0.1 part, resin fine particle J-140A (manufactured by Seiko PMC, solid content 41.0% by weight) 19.5 parts, pigment dispersion CAB-O-JET 250C (manufactured by Cabot Specialty Chemicals Inc.) 26.1 parts of solid content 10.0% by weight) and 1.7 parts of urethane-modified polyether-based associative thickener SN thickener 625N (San Nopco, solid content 15.0% by weight) in a 25 ° C. environment. After mixing and stirring, ink 2 was obtained by filtration through a 3 μm cellulose acetate filter.

(Example 3)
33.3 parts of water, 10.0 parts of propylene glycol, 5.0 parts of 2-methyl-1,3-propanediol, 1.0 part of Orphine E1010 (manufactured by Nissin Chemical Industry Co., Ltd.), FT 251 (manufactured by Neos) ) 0.1 part, resin fine particle J-140A (manufactured by Seiko PMC, solid content 41.0% by weight) 19.5 parts, pigment dispersion CAB-O-JET 250C (manufactured by Cabot Specialty Chemicals Inc.) 26.1 parts of solid content 10.0% by weight) and 5.0 parts of urethane-modified polyether-based associative thickener SN thickener 625N (manufactured by San Nopco, solid content 15.0% by weight) in a 25 ° C. environment. After mixing and stirring, ink 3 was obtained by filtration through a 3 μm cellulose acetate filter.

Example 4
41.1 parts of water, 10.0 parts of propylene glycol, 5.0 parts of 2-methyl-1,3-propanediol, 1.0 part of Orphine E1010 (manufactured by Nissin Chemical Industry Co., Ltd.), FT 251 (manufactured by Neos) ) 0.1 part, resin fine particle J-140A (manufactured by Seiko PMC, solid content 41.0% by weight) 19.5 parts, dye dispersion Duasynjet M250 (manufactured by Clariant, solid content 10.0% by weight) 0 parts and 3.3 parts of urethane-modified polyether-based associative thickener SN thickener 625N (manufactured by San Nopco, solid content 15.0% by weight) were mixed and stirred in a 25 ° C. environment, and then 3 μm cellulose acetate filter. Ink 4 was obtained by filtration.

(Example 5)
38.4 parts of water, 10.0 parts of propylene glycol, 5.0 parts of 2-methyl-1,3-propanediol, 1.0 part of Orphine E1010 (manufactured by Nissin Chemical Industry Co., Ltd.), and 251 251 (manufactured by Neos) ) 0.1 part, water-soluble resin X-01 (manufactured by Seiko PMC, solid content 24.8% by weight) 16.1 parts, pigment dispersion CAB-O-JET 250C (manufactured by Cabot Specialty Chemicals Inc.) 26.1 parts of solid content 10.0 wt%) and 3.3 parts of urethane-modified polyether associative thickener SN thickener 625N (San Nopco, solid content 15.0 wt%) in a 25 ° C. environment. After mixing and stirring, the ink 5 was obtained by filtration through a 3 μm cellulose acetate filter.

(Comparative Example 1)
38.3 parts of water, 10.0 parts of propylene glycol, 5.0 parts of 2-methyl-1,3-propanediol, 1.0 part of Orphine E1010 (manufactured by Nissin Chemical Industry Co., Ltd.), Phthagene 251 (manufactured by Neos) 0.1 part, 19.5 parts of resin fine particles J-140A (manufactured by Seiko PMC, solid content 41.0% by weight), and pigment dispersion CAB-O-JET 250C (manufactured by Cabot Specialty Chemicals Inc.) Ink 6 was obtained by mixing and stirring 26.1 parts (solid content 10.0 wt%) in a 25 ° C. environment and then filtering through a 3 μm cellulose acetate filter.

(Comparative Example 2)
190.0 parts of water and 10.0 g of carboxymethylcellulose (CEKOL100,000, manufactured by Sanki Co., Ltd.) were stirred while heating to 45 ° C. to obtain a thickener aqueous solution A having a solid content of 5.0% by weight. 18.3 parts of water, 10.0 parts of propylene glycol, 5.0 parts of 2-methyl-1,3-propanediol, 1.0 part of Olphine E1010 (manufactured by Nissin Chemical Industry Co., Ltd.), and 251 251 (manufactured by Neos) ) 0.1 part, resin fine particle J-140A (manufactured by Seiko PMC, solid content 41.0% by weight) 19.5 parts, pigment dispersion CAB-O-JET 250C (manufactured by Cabot Specialty Chemicals Inc.) Ink 7 was obtained by mixing and stirring 26.1 parts (solid content 10.0 wt%) and 20.0 parts thickener aqueous solution A in an environment of 25 ° C. and then filtering through a 3 μm cellulose acetate filter.

(Comparative Example 3)
198.0 parts of water and 2.0 g of xanthan gum (KELZAN S, manufactured by Sanki Co., Ltd.) were stirred while heating to 45 ° C. to obtain a thickener aqueous solution B having a solid content of 1.0% by weight. 33.3 parts of water, 10.0 parts of propylene glycol, 5.0 parts of 2-methyl-1,3-propanediol, 1.0 part of Orphine E1010 (manufactured by Nissin Chemical Industry Co., Ltd.), FT 251 (manufactured by Neos) ) 0.1 part, resin fine particle J-140A (manufactured by Seiko PMC, solid content 41.0% by weight) 19.5 parts, pigment dispersion CAB-O-JET 250C (manufactured by Cabot Specialty Chemicals Inc.) Ink 8 was obtained by mixing and stirring 26.1 parts (solid content 10.0 wt%) and 5.0 parts thickener aqueous solution B in a 25 ° C. environment and then filtering through a 3 μm cellulose acetate filter.

(Comparative Example 4)
140.0 parts of water and 60.0 g of polyethylene glycol (PEG-20000, manufactured by Sanyo Chemical Co., Ltd.) were stirred while heating to 45 ° C. to obtain a thickener aqueous solution C having a solid content of 30.0% by weight. 25.0 parts of water, 10.0 parts of propylene glycol, 5.0 parts of 2-methyl-1,3-propanediol, 1.0 part of Orphine E1010 (manufactured by Nissin Chemical Industry Co., Ltd.), Footage 251 (manufactured by Neos) ) 0.1 part, resin fine particle J-140A (manufactured by Seiko PMC, solid content 41.0% by weight) 19.5 parts, pigment dispersion CAB-O-JET 250C (manufactured by Cabot Specialty Chemicals Inc.) 26.1 parts of solid content (10.0 wt%) and 13.3 parts of thickener aqueous solution C were mixed and stirred in a 25 ° C. environment, and then filtered through a 3 μm cellulose acetate filter to obtain ink 9.

(Comparative Example 5)
Stirring while heating 170.0 parts of water and 30.0 g of polyaminoplastol ether-based associative thickener TVS-VF (by Big Chemie Japan, solid content 40.0% by weight) to 45 ° C., solid content A 6.0 wt% thickener aqueous solution D was obtained. 12.3 parts of water, 10.0 parts of propylene glycol, 5.0 parts of 2-methyl-1,3-propanediol, 1.0 part of Olphine E1010 (manufactured by Nissin Chemical Industry Co., Ltd.), FT 251 (manufactured by Neos) ) 0.1 part, resin fine particle J-140A (manufactured by Seiko PMC, solid content 41.0% by weight) 19.5 parts, pigment dispersion CAB-O-JET 250C (manufactured by Cabot Specialty Chemicals Inc.) 26.1 parts of solid content 10.0 wt%) and 12.3 parts thickener aqueous solution D were mixed and stirred in a 25 ° C. environment, and then filtered through a 3 μm cellulose acetate filter to obtain ink 10.

(Evaluation method)
The ink characteristics of Examples and Comparative Examples obtained as described above were evaluated by the following methods and criteria.

<Image bleeding>
A platen heater of an inkjet printer VG-640 (manufactured by Roland DG Inc.) is set to 60 ° C., and a predetermined evaluation image including characters and fine lines is printed on a PET film in a standard mode. After standing for 24 hours in an environment of 23 ° C. and 50% RH, the image quality of characters and fine lines is visually evaluated in four stages.
◎ ・ ・ ・ Blurred image is good ○ ・ ・ ・ Blurred image is seen but image quality is within acceptable range Δ ・ ・ ・ Blurred image is seen and affects image quality ..Bleeding of images is seen and greatly affects image quality

<Drying>
A platen heater of an inkjet printer VG-640 (manufactured by Roland DG Inc.) is set to 60 ° C., and a solid image is printed on a PET film in a standard mode. After 5 minutes, the PET film and 300 g of weight are placed on the image surface and left in an environment of 23 ° C. and 50% RH for 24 hours. Thereafter, both are peeled off, and the peeled state of the image is visually evaluated in four stages.
◎ ・ ・ ・ No peeling is observed ○ ・ ・ ・ Peeling is observed in an area of less than 1% Δ ・ ・ ・ Peeling is observed in an area of 1% or more and less than 10% ×× In an area of 10% or more There is peeling

<Base material adhesion>
A platen heater of an inkjet printer VG-640 (manufactured by Roland DG Inc.) is set to 60 ° C., and a solid image is printed on a PET film in a standard mode. After leaving for 24 hours in an environment of 23 ° C. and 50% RH, six cuts are made at 1 mm intervals using spacers with equal intervals on the image surface, and the spacers are further rotated by 90 °. This cuts 25 squares. A tape with a width of 30 mm is attached from above so that at least 25 squares are cut and pressed with a finger to make an appropriate contact. Thereafter, the tape is peeled off at an angle of 60 ° within 1.0 seconds, and the peeled state of the image of the cut portion is visually evaluated in four stages.
◎ ・ ・ ・ No peeling is observed ○ ・ ・ ・ Incision part is seen in a line shape Δ ・ ・ ・ Peeling is seen at the intersection part × ・ ・ ・ Peeling is seen over the entire image

<Transparency>
A platen heater of an inkjet printer VG-640 (manufactured by Roland DG Inc.) is set to 60 ° C., and a solid image is printed on a PET film in a standard mode. After being allowed to stand for 24 hours in an environment of 23 ° C. and 50% RH, the haze value is obtained with a spectral haze meter SH7000 (manufactured by Nippon Denshoku Industries Co., Ltd.).
◎ ... less than 20% ○ ... 20% or more but less than 50% △ ... 50% or more but less than 70% × ... 70% or more

<Abrasion>
A platen heater of an inkjet printer VG-640 (manufactured by Roland DG Inc.) is set to 60 ° C., and a solid image is printed on a PET film in a standard mode. After leaving for 24 hours in an environment of 23 ° C. and 50% RH, attach a white cotton cloth (gold width 3) to the Gakushin type friction fastness tester AB-301 (manufactured by Tester Sangyo Co., Ltd.) and load 100 reciprocations are performed at a load of 500 g and a repetitive speed of 30 reciprocations per minute. The peeled state of the image of the tested part is evaluated visually in four stages.
◎ ・ ・ ・ No peeling is observed ○ ・ ・ ・ Peeling is observed in an area of less than 10% Δ ・ ・ ・ Peeling is observed in an area of 10% or more and less than 25% × ・ ・ ・ In an area of 25% or more There is peeling

<Water resistance>
A platen heater of an inkjet printer VG-640 (manufactured by Roland DG Inc.) is set to 60 ° C., and a solid image is printed on a PET film in a standard mode. White cotton cloth (Gold width 3) with water in Gakushin type friction fastness tester AB-301 (manufactured by Tester Sangyo Co., Ltd.) after leaving it to stand at 23 ° C. and 50% RH for 24 hours. ), And 100 reciprocations at a load of 200 g and a repetitive speed of 30 reciprocations per minute. The peeled state of the image of the tested part is evaluated visually in four stages.
◎ ・ ・ ・ No peeling is observed ○ ・ ・ ・ Peeling is observed in an area of less than 10% Δ ・ ・ ・ Peeling is observed in an area of 10% or more and less than 25% × ・ ・ ・ In an area of 25% or more There is peeling

  Table 1 shows the compositions of the inkjet inks of Examples 1 to 5 and Comparative Examples 1 to 5, and Table 2 shows the evaluation results.

  Comparative Example 1 is an example where no thickener was added. From comparison between Examples 1 to 5 and Comparative Example 1, it can be seen that image bleeding is suppressed by using a urethane-modified polyether-based associative thickener. In addition, the evaluation results of the drying properties and image characteristics of Examples 1 to 5 are the same as or similar to those of Comparative Example 1, and it can be seen that the drying properties and image characteristics are good. Comparative Examples 2 to 4 are systems to which a water-soluble thickener is added. From comparison between Examples 1 to 5 and Comparative Examples 2 to 4, it can be seen that image bleeding is suppressed by using the urethane-modified polyether-based associative thickener. It can also be seen that Examples 1 to 5 have higher drying properties and image characteristics than Comparative Examples 2 to 4. Comparative Example 5 is a system to which a polyaminoplastol ether-based associative thickener is added. The ink produced in Comparative Example 5 was irreversibly altered when the amount of drying was reduced. Further, from the comparison between Examples 1 to 5 and Comparative Example 5, in order to obtain the effects of suppression of image bleeding and good drying properties and image characteristics, among the associative thickeners, urethane-modified polyether-based associations It turns out that a sex thickener should be used. Further, in Examples 1 to 4, hydrophobic resin fine particles were used as the resin component, and in Example 5, a water-soluble resin was used as the resin component, but the resin component was either a hydrophobic resin fine particle or a water-soluble resin. Even so, it can be seen that good results are obtained.

  The ink-jet ink of the present invention can be suitably used for image recording (printing) on a hardly absorbent recording medium.

DESCRIPTION OF SYMBOLS 10 Recording medium 11 Ink 20 Conveying part 21 Supply roller 22 Winding roller 23 Conveying roller 30 Platen 40 Heating part 50 Ejecting part 60 Ink accommodating part 70 Drying part 71 Carriage 100 Inkjet recording apparatus

Claims (9)

  An inkjet ink comprising at least water, a resin component, a coloring material, and an associative thickener, wherein the associative thickener is a urethane-modified polyether polymer. The inkjet ink according to claim 1, wherein the following equation is established when the viscosity at 25 ° C. is V1, the viscosity at 40 ° C. is V2, and the viscosity at 40 ° C. is 10% by weight after drying loss.
5.0 mPa · s ≦ V1 ≦ 20.0 mPa · s
V1 / V2 ≧ 1.6
V3 / V2 ≧ 1.3   The inkjet ink according to claim 1, wherein the resin component is resin fine particles.   The inkjet ink according to claim 1, wherein the colorant is a pigment.   Furthermore, the inkjet ink of any one of Claims 1-4 containing an organic solvent.   Furthermore, the inkjet ink of any one of Claims 1-5 containing surfactant.   The inkjet ink of any one of Claims 1-6 whose solid content concentration is 20.0 weight% or less. Heating the hardly absorbent recording medium;
A step of ejecting inkjet ink to the heated hardly absorbent recording medium;
An inkjet recording method comprising:
The inkjet recording method whose said inkjet ink is the inkjet ink of any one of Claims 1-7. A transport unit for transporting the hardly absorbent recording medium;
A heating section for heating the conveyed hardly absorbent recording medium,
A discharge section for discharging inkjet ink onto the heated hardly-absorbable recording medium;
An ink storage unit that stores the inkjet ink and supplies the inkjet ink to the ejection unit;
An inkjet recording apparatus comprising:
The inkjet recording device whose inkjet ink is the inkjet ink of any one of Claims 1-7.

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