Ink, ink set, ink container, printing method, and printing device

Abstract

To provide an ink that can prevent the occurrence of beading and color bleeding in a printed image.SOLUTION: An ink contains an anionic compound, organic solvents, water, and a photoacid generator, the organic solvents including at least one organic solvent having a solubility parameter of from 9 to 11.8 (J / cm3)1 / 2.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an ink, an ink set, an ink container, a printing method, and a printing apparatus. [Background technology]

[0002] In recent years, inkjet recording methods have rapidly become popular because they can easily record color images and have low running costs. However, inkjet recording methods have the problem that, depending on the combination of ink and recording medium, image defects such as character bleeding are likely to occur, resulting in a significant decrease in image quality. Furthermore, there is a demand for higher productivity and faster printing speeds for inkjet recording devices, which has resulted in various problems.

[0003] For example, non-permeable media for signage and the like do not absorb ink, which can lead to problems such as severe image bleeding (color bleeding), uneven density of solid images (beading), and poor ink fixation. Furthermore, when recording on coated paper that uses fillers such as calcium carbonate or kaolin as coating layer materials, such as coated paper for commercial printing or publication printing, the image can suffer from severe image bleeding (color bleeding), uneven density of solid images (beading), and reduced image density. Therefore, for example, in order to suppress color bleeding and beading, an inkjet recording method has been proposed in which a recording medium whose surface has been modified by either corona discharge treatment or plasma treatment is combined with an ink containing an amide compound (see, for example, Patent Document 1). In addition, the solubility parameter is 9( cal / cm 3 ) 1 / 2 Over 11.8( cal / cm 3 ) 1 / 2 An ink has been proposed that contains an organic solvent of less than 34.0 mN / m and has a dynamic surface tension of 34.0 mN / m or less at a surface life of 15 msec as measured by the maximum bubble pressure method (see, for example, Patent Document 2). Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide an ink that can suppress the occurrence of beading and color bleeding in printed images. [Means for solving the problem]

[0005] The ink of the present invention as a means for solving the above problems contains an anionic compound, an organic solvent, water, and a photoacid generator, and the organic solvent has a solubility parameter of 9 ( cal / cm 3 ) 1 / 2 Over 11.8( cal / cm 3 ) 1 / 2 It contains at least one of the following organic solvents: [Effects of the Invention]

[0006] According to the present invention, it is possible to provide an ink that can suppress the occurrence of beading and color bleeding in printed images. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic front view showing an example of a printing apparatus of the present invention. [Figure 2] FIG. 2 is a schematic side view showing an example of the printing apparatus of the present invention. [Figure 3] FIG. 3 is a partially enlarged view showing an example of the printing device of the present invention. [Figure 4] FIG. 4 is a schematic perspective view showing an example of an ink containing container. DETAILED DESCRIPTION OF THE INVENTION

[0008] (ink) The ink of the present invention contains an anionic compound, an organic solvent, water, and a photoacid generator, and the organic solvent has a solubility parameter of 9 ( cal / cm 3 ) 1 / 2 Over 11.8( cal / cm3 ) 1 / 2 It contains at least one of the following organic solvents, and may further contain other components as required.

[0009] The prior art has the problem that beading and color bleeding occur in printed images on non-permeable or poorly permeable media when printing at high speeds.

[0010] In the present invention, an ink containing an anionic compound, an organic solvent, water, and a photoacid generator is used to print on a recording medium, and then the ink is irradiated with appropriate ultraviolet light immediately after printing, thereby decomposing the photoacid generator. The photoacid generator decomposes to generate an acid, which aggregates or thickens the anionic compound (at least one of an anionic resin and an anionic pigment). As a result, beading and color bleeding in printed images can be suppressed during high-speed printing.

[0011] <Photoacid generator> The photoacid generator is a compound that decomposes upon irradiation with ultraviolet light to generate an acid, and is preferably, for example, either a compound represented by the following general formula (I) or a compound represented by the following general formula (II):

[0012] <Compound represented by general formula (I)> [ka] In the general formula (I), R1, R2, and R3 each represent a hydrogen atom, a lower alkyl group having 1 to 4 carbon atoms, an alkoxy group, or a thiophenyl group. m represents 0 or an integer of 1 to 3. Counter ion X - is F3CSO3 - , F9C4SO3 - , CH3C6H4SO3 - , PF6 - , SbF6 - , (Rf) n PF 6-n - , 10-camphor SO3 - , or B(C6F5)4 -(wherein Rf is a fluorocarbon alkyl group, and n is an integer of 1 to 5).

[0013] A specific example of a suitable compound represented by the general formula (I) is a compound represented by the following general formula (I-1).

[0014] [ka] However, in the general formula (I-1), X2 - PF6 - , SbF6 - , or (Rf) n PF 6-n - wherein Rf is a fluorocarbon alkyl group and n is an integer of 1 to 5.

[0015] Examples of the compound represented by the general formula (I-1) include compounds represented by the following structural formulas (1) to (3).

[0016] [Structural formula (1)] [ka]

[0017] [Structural formula (2)] [ka]

[0018] [Structural formula (3)] [ka] Here, Rf is a fluorocarbon alkyl group, and n is an integer of 1 to 5.

[0019] As the compound represented by the general formula (I-1), commercially available products can be used, and examples of the commercially available products include CPI-100P, CPI-101A, CPI-200A, and CPI-210S manufactured by San-Apro Co., Ltd.

[0020] A specific example of a suitable compound represented by the general formula (I) is a compound represented by the following general formula (I-2).

[0021] [ka] In the general formula (I-2), R7, R8, and R9 are each a hydrogen atom or a lower alkyl group having 1 to 4 carbon atoms, and X3 - is F3CSO3 ー , F9C4SO3 - , 10-camphor SO3 - , B(C6F5)4 - , or (Rf) n PF 6-n - wherein Rf is a fluorocarbon alkyl group and n is an integer of 1 to 5.

[0022] Examples of the compound represented by the general formula (I-2) include compounds represented by the following structural formulas (4) to (6).

[0023] [Structural formula (4)] [ka]

[0024] [Structural formula (5)] [ka]

[0025] [Structural formula (6)] [ka]

[0026] The compound represented by the general formula (I-2) can be a commercially available product, and examples of the commercially available product include CPI-310B and CPI-410S manufactured by San-Apro Ltd.; TPS-TF, TPS-PFBS, and TPS-CS manufactured by Toyo Gosei Co., Ltd.; and WPAG-336, WPAG-469, and WPAG-638 manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.

[0027] A specific example of a suitable compound represented by the general formula (I) is a compound represented by the following general formula (I-3).

[0028] [ka] However, in the general formula (I-3), R 10 is a methyl group or a methoxy group, and X4 - is F3CSO3 - , or CH3C6H4SO3 - Shows.

[0029] Examples of the compound represented by the general formula (I-3) include compounds represented by the following structural formulas (7) and (8).

[0030] [Structural formula (7)] [ka]

[0031] [Structural formula (8)] [ka]

[0032] As the compound represented by the general formula (I-3), commercially available products can be used, and examples of the commercially available products include WPAG-367 and WPAG-370 manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.

[0033] <Compound represented by general formula (II)> [ka] In the general formula (II), R4 represents a hydrogen atom or a lower alkyl group having 1 to 4 carbon atoms. R5 represents a hydrogen atom, a lower alkyl group having 1 to 4 carbon atoms, a phenyl group, a substituted phenyl group, or a naphthalene group. R6 represents a hydrogen atom, a lower alkyl group having 1 to 4 carbon atoms, an acetyl group, or a methoxycarbonyl group. Counter ion X1 - PF6 - , SbF6 - , or B(C6F5)4 - Shows.

[0034] A specific example of a suitable compound represented by the general formula (II) is a compound represented by the following general formula (II-1). [ka] However, in the general formula (II-1), R 11 is a hydrogen atom or a lower alkyl group having 1 to 4 carbon atoms, and the counter ion X5 - PF6 - , SbF6 - , or B(C6F5)4 - Shows.

[0035] Examples of the compound represented by the general formula (II-1) include compounds represented by the following structural formulas (9) and (10).

[0036] [Structural formula (9)] [ka]

[0037] [Structural formula (10)] [ka]

[0038] The compound represented by the general formula (II-1) can be a commercially available product, and examples of the commercially available product include San-Aid SI-80, San-Aid SI-100, and San-Aid SI-110 manufactured by Sanshin Chemical Industry Co., Ltd.

[0039] A specific example of a suitable compound represented by the general formula (II) is a compound represented by the following general formula (II-2).

[0040] [ka] However, in the general formula (II-2), the counter ion X6 - PF6 - , SbF6 - , or B(C6F5)4 - Shows.

[0041] Examples of the compound represented by the general formula (II-2) include a compound represented by the following structural formula (11).

[0042] [Structural formula (11)] [ka]

[0043] The compound represented by the general formula (II-2) can be a commercially available product, and examples of the commercially available product include San-Aid SI-60 and San-Aid SI-360 manufactured by Sanshin Chemical Industry Co., Ltd.

[0044] A specific example of a suitable compound represented by the general formula (II) is a compound represented by the following general formula (II-3).

[0045] [ka] However, in the general formula (II-3), R 11 is a hydrogen atom or a lower alkyl group having 1 to 4 carbon atoms, and the counter ion X7- PF6 - , SbF6 - , or B(C6F5)4 - Shows.

[0046] Examples of the compound represented by the general formula (II-3) include compounds represented by the following structural formula (12).

[0047] [Structural formula (12)] [ka]

[0048] [Structural formula (13)] [ka]

[0049] [Structural formula (14)] [ka]

[0050] The compound represented by the general formula (II-3) can be a commercially available product, and examples of the commercially available product include San-Aid SI-300, San-Aid SI-B2A, and San-Aid SI-B3A manufactured by Sanshin Chemical Industry Co., Ltd.

[0051] The content of the photoacid generator is preferably 0.25% by mass to 5% by mass, and more preferably 0.5% by mass to 4% by mass, based on the total amount of the ink, from the viewpoint of suppressing color bleeding and beading. When the content of the photoacid generator is 0.25% by mass or more, good beading and color bleeding effects can be obtained, and when the content of the photoacid generator is 5% by mass or less, good effects can be obtained.

[0052] <Organic solvents> As an organic solvent, the solubility parameter is 9( cal / cm 3) 1 / 2 Over 11.8( cal / cm 3 ) 1 / 2 At least one of the following organic solvents is contained. In particular, the solvent has a solubility parameter of 9( cal / cm 3 ) 1 / 2 Over 11.8( cal / cm 3 ) 1 / 2 It is preferable that the content of the organic solvent is less than 100%. Solubility parameter 9( cal / cm 3 ) 1 / 2 Over 11.8( cal / cm 3 ) 1 / 2 The following organic solvents include, for example, 3-ethyl-3-oxetanemethanol (SP value: 11.31 ( cal / cm 3 ) 1 / 2 ), 3-methyl-3-oxetanemethanol (SP value: 11.79 ( cal / cm 3 ) 1 / 2 ), 3-methoxy-N,N-dimethylpropionamide (SP value: 9.19 ( cal / cm 3 ) 1 / 2 ), 3-butoxy-N,N-dimethylpropionamide (SP value: 9.03 ( cal / cm 3 ) 1 / 2 ), 1,2-hexanediol (SP value: 11.80 ( cal / cm 3 ) 1 / 2 ), 2-ethyl-1,3-hexanediol (SP value: 11.07 ( cal / cm 3 ) 1 / 2 ), 2,2,4-trimethyl-1,3-pentanediol (SP value: 11.19 ( cal / cm 3 ) 1 / 2 ), diethylene glycol monoethyl ether (SP value: 10.14 ( cal / cm 3 ) 1 / 2 ), 3-methoxy-1-butanol (SP value: 9.64 ( cal / cm 3) 1 / 2 ), 3-methoxy-3-methyl-1-butanol (SP value: 9.64 ( cal / cm 3 ) 1 / 2 ), methyl propylene triglyceride (SP value: 9.43 ( cal / cm 3 ) 1 / 2 ), diethylene glycol mono-n-butyl ether (SP value: 9.86 ( cal / cm 3 ) 1 / 2 ), diethylene glycol monomethyl ether (SP value: 10.34 ( cal / cm 3 ) 1 / 2 ), triethylene glycol monomethyl ether (SP value: 10.12 ( cal / cm 3 ) 1 / 2 ), propylene glycol monopropyl ether (SP value: 9.82 ( cal / cm 3 ) 1 / 2 ), propylene glycol monomethyl ether (SP value: 10.19 ( cal / cm 3 ) 1 / 2 ), propylene glycol monobutyl ether (SP value: 9.69 ( cal / cm 3 ) 1 / 2 ), 3-methoxy-1-butanol (SP value: 10.65 ( cal / cm 3 ) 1 / 2 ), 3-methoxy-1-propanol (SP value: 10.41 ( cal / cm 3 ) 1 / 2 ), dipropylene glycol monomethyl ether (SP value: 9.84 ( cal / cm 3 ) 1 / 2 ), 3-methyl-1,5-pentanediol (SP value: 11.80 ( cal / cm 3 ) 1 / 2 These may be used alone or in combination of two or more.

[0053] Solubility parameter 9( cal / cm 3 ) 1 / 2 Over 11.8( cal / cm 3 ) 1 / 2 The content of the following organic solvents is preferably from 5% to 60% by mass, and more preferably from 10% to 30% by mass, of the total amount of ink, from the viewpoints of color development, color bleeding, and beading suppression.

[0054] In addition, the solubility parameter is 9( cal / cm 3 ) 1 / 2 Over 11.8( cal / cm 3 ) 1 / 2 As an organic solvent other than the following organic solvents, a polyhydric alcohol having an equilibrium water content of 30% by mass or more at a temperature of 23° C. and a relative humidity of 80% can be contained as a wetting agent. Among these, those having a high equilibrium water content and a high boiling point are preferred. Examples of polyhydric alcohols having an equilibrium water content of 30% by mass or more at a temperature of 23°C and a relative humidity of 80% include diethylene glycol (bp 245°C, equilibrium water content 43% by mass), triethylene glycol (bp 285°C, equilibrium water content 39% by mass), tetraethylene glycol (bp 324°C to 330°C, equilibrium water content 37% by mass), 1,3-butanediol (bp 203°C to 204°C, equilibrium water content 35% by mass), glycerin (bp 290°C, equilibrium water content 49% by mass), diglycerin (bp 270°C / 20 hPa, equilibrium water content 38% by mass), 1,2,3-butanetriol (bp 175°C / 33 hPa, equilibrium water content 38% by mass), and 1,2,4-butanetriol (bp 190°C to 191°C / 24 hPa, equilibrium water content 41% by mass). These may be used alone or in combination. Among these, glycerin and 1,3-butanediol are preferred.

[0055] The equilibrium moisture content (%) was calculated by using a saturated aqueous solution of potassium chloride / sodium chloride in a desiccator, maintaining the temperature and humidity at 23°C ± 1°C and a relative humidity of 80% ± 3%, storing petri dishes containing 1 g of each organic solvent in the desiccator, measuring the equilibrium moisture content, and calculating it using the following formula. Equilibrium moisture content (%) = [amount of water absorbed by organic solvent / (organic solvent + amount of water absorbed by organic solvent)] x 100

[0056] The above solubility parameter 9( cal / cm 3 ) 1 / 2 Over 11.8( cal / cm 3 ) 1 / 2 Examples of organic solvents other than the following organic solvents and polyhydric alcohols having an equilibrium moisture content of 30% by mass or more under an environment of a temperature of 23°C and a relative humidity of 80% include 2-methyl-1,3-butanediol (bp: 214°C), 3-methyl-1,3-butanediol (bp: 203°C), dipropylene glycol (bp: 232°C), 1,5-pentanediol (bp: 242°C), propylene glycol (bp: 187°C), 2-methyl-2,4-pentanediol (bp: 197°C), ethylene glycol (bp: 197°C), propylene glycol (bp: 232°C), 1,5-pentanediol (bp: 242°C), propylene glycol (bp: 187°C), 2-methyl-2,4-pentanediol (bp: 197°C), ethylene ...1,5-pentanediol (bp: 242°C), 1,5 Examples include polyethylene glycol (bp: 196°C to 198°C), tripropylene glycol (bp: 267°C), hexylene glycol (bp: 197°C), polyethylene glycol (viscous liquid to solid), polypropylene glycol (bp: 187°C), 1,6-hexanediol (bp: 253°C to 260°C), 1,2,6-hexanetriol (bp: 178°C), trimethylolethane (solid, mp: 199°C to 201°C), and trimethylolpropane (solid, mp: 61°C).

[0057] The total content of the organic solvents is preferably 10% by mass or more and 75% by mass or less, and more preferably 15% by mass or more and 50% by mass or less, based on the total amount of the ink. When the total content is 10% by mass or more, the ink has a good moisturizing effect, and when it is 75% by mass or less, the ink dries well on the recording medium and the quality of characters on plain paper is also good. The organic solvent is also involved in suppressing color bleeding and beading, but is also useful for ensuring ejection stability and preventing waste ink from sticking to the maintenance device of the ink ejection device, so it is preferable to use the organic solvent in an appropriate range.

[0058] The ink may contain a water-soluble organic solvent other than the organic solvents mentioned above. Examples of the water-soluble organic solvent include polyhydric alcohol aryl ethers, nitrogen-containing heterocyclic compounds, amides, amines, sulfur-containing compounds, propylene carbonate, ethylene carbonate, and other wetting agents. Examples of the polyhydric alcohols include 2-methyl-1,3-butanediol (bp: 214°C), 3-methyl-1,3-butanediol (bp: 203°C), dipropylene glycol (bp: 232°C), 1,5-pentanediol (bp: 242°C), propylene glycol (bp: 187°C), 2-methyl-2,4-pentanediol (bp: 197°C), ethylene glycol (bp: 196°C to 198°C), triproleum Examples include pyrene glycol (bp: 267°C), hexylene glycol (bp: 197°C), polyethylene glycol (viscous liquid to solid), polypropylene glycol (bp: 187°C), 1,6-hexanediol (bp: 253°C to 260°C), 1,2,6-hexanetriol (bp: 178°C), trimethylolethane (solid, mp: 199°C to 201°C), and trimethylolpropane (solid, mp: 61°C).

[0059] As other wetting agents, sugars and the like are preferred. Examples of sugars include monosaccharides, disaccharides, oligosaccharides (including trisaccharides and tetrasaccharides), and polysaccharides. Specific examples of sugars include glucose, mannose, fructose, ribose, xylose, arabinose, galactose, maltose, cellobiose, lactose, sucrose, trehalose, and maltotriose. Here, the term "polysaccharides" refers to sugars in a broad sense, and is used to mean substances that are widely present in nature, such as α-cyclodextrin and cellulose. In addition, derivatives of these sugars include reducing sugars of the above-mentioned sugars {for example, sugar alcohols [general formula: HOCH2(CHOH) n CH2OH (where n is an integer of 2 to 5). ]}, sugar oxides (for example, aldonic acid, uronic acid, etc.), amino acids, thioacids, etc. Among these, sugar alcohols are preferred, and examples of the sugar alcohols include maltitol and sorbitol.

[0060] The mass ratio of the colorant to the water-soluble organic solvent has a significant effect on the stability of ink ejection from the head, and also has an effect on preventing waste ink from sticking to the maintenance device of the ink ejection device. If the solid content of the colorant is high but the amount of the water-soluble organic solvent is low, evaporation of water near the ink meniscus of the nozzle may occur, which may result in poor ejection.

[0061] <Anionic compounds> As the anionic compound, at least one of an anionic resin and an anionic pigment is used.

[0062] <<Resin>> The resin is not particularly limited as long as it has anionic properties, but a water-dispersible resin having anionic properties is preferred.

[0063] -Water dispersible resin- Water-dispersible resins that have excellent film-forming properties (image-forming properties) and solvent resistance, high water resistance, and high weather resistance are useful for recording images with high water resistance and high image density (high color development), and examples of these include condensation-based synthetic resins, addition-based synthetic resins, natural polymer compounds, etc. Among these, polyurethane resins are preferred. Furthermore, because non-permeable media for signage have poor ink fixation properties, it is necessary to select the right material for water-dispersible resin particles and increase the amount added.Furthermore, to improve the fixation properties of non-permeable media films, polyurethane resin particles synthesized from polyol raw materials containing aromatic rings, which have the structure shown in the following structural formula (A), are often used.

[0064] [ka]

[0065] Examples of polyol raw materials containing an aromatic ring having the structure represented by the structural formula (A) include terephthalic acid and isophthalic acid. When terephthalic acid or isophthalic acid is used as a raw material, a cyclic ester compound is produced. When the above two types of raw materials are used, it has been confirmed by GC-MS that a cyclic ester containing a mixture of two types of phthalic acid is produced. The polyurethane resin particles preferably contain polyurethane resin particles having the structure represented by the structural formula (A) above, using a polyol raw material containing an aromatic ring having the structure represented by the structural formula (A) above as the raw material for the polyurethane resin particles. The proportion of the polyol raw material containing an aromatic ring having the structure represented by the structural formula (A) in the polyurethane resin particles having the structure represented by the structural formula (A) is preferably about half of the polyol and about 10 to 30% of the polyurethane resin. When the proportion of the polyol raw material is within the above range, excellent alcohol resistance is achieved.

[0066] Other condensation-based synthetic resins include, for example, polyester resins, polyurethane resins, polyepoxy resins, polyamide resins, polyether resins, poly(meth)acrylic resins, acrylic-silicone resins, and fluorine-based resins. Examples of the addition-based synthetic resins include, for example, polyolefin resins, polystyrene-based resins, polyvinyl alcohol-based resins, polyvinyl ester-based resins, polyacrylic acid-based resins, and unsaturated carboxylic acid-based resins. Examples of the natural polymer compounds include, for example, celluloses, rosins, and natural rubber. Among these, polyurethane resin particles are preferred in consideration of the fixability of the ink. Two or more of the above water-dispersible resins may be used in combination.

[0067] As the water-dispersible resin, those which have hydrophilic groups and are self-dispersible, and those which do not have dispersibility but are provided with dispersibility by surfactants or resins with hydrophilic groups can be used. Among these, emulsions of resin particles obtained by emulsifying and suspension polymerizing ionomers of polyester resins or polyurethane resins or unsaturated monomers are the most suitable. In the case of emulsion polymerization of unsaturated monomers, a resin emulsion is obtained by reacting the unsaturated monomer, a polymerization initiator, a surfactant, a chain transfer agent, a chelating agent, a pH adjuster, and the like in water to which the unsaturated monomer, a polymerization initiator, a surfactant, a chain transfer agent, a chelating agent, a pH adjuster, and the like have been added. This makes it easy to obtain a water-dispersible resin, and it is easy to change the resin composition and to create the desired properties.

[0068] Since the water-dispersible resin undergoes dispersion destruction or hydrolysis or other cleavage of molecular chains under strong alkaline or strong acidic conditions, the pH is preferably 4 to 12, and from the viewpoint of miscibility with the water-dispersible colorant in particular, a pH of 7 to 11 is more preferable, and a pH of 8 to 10.5 is even more preferable.

[0069] The water-dispersible resin functions to fix the water-dispersible colorant to the recording medium, and improves the fixation of the colorant by forming a film at room temperature or higher. Therefore, the minimum film-forming temperature (MFT) of the water-dispersible resin is preferably 100°C or lower. Furthermore, if the glass transition temperature of the water-dispersible resin is −40° C. or lower, the viscosity of the resin film increases and tackiness occurs in the printed matter, so the glass transition temperature is preferably −30° C. or higher. The content of the water-dispersible resin in the ink is preferably 0.5% by mass or more and 20% by mass or less, and more preferably 1% by mass or more and 15% by mass or less, in terms of solid content. However, when full consideration is given to the substrate fixation of the colorant to non-penetrable media for signage and commercial printing paper, the content of polyurethane resin particles in the ink is 3% by mass or more, and the solids mass ratio of colorant to polyurethane resin particles is preferably 1.0: (2.0 to 12.0), more preferably 1.0: (2.0 to 11.0).When producing the ink, the polyurethane resin particles are used in the form of a dispersion, and the content of polyurethane resin particles in the ink refers to the content of polyurethane resin particles, which are the solids in the ink.

[0070] <<Coloring agent>> The ink of the present invention may be a clear ink that does not contain a colorant, but preferably contains a colorant. The colorant is not particularly limited as long as it has anionic properties, but anionic pigments are preferred. Examples of anionic pigments include surfactant dispersions in which a pigment is dispersed in a surfactant, resin dispersions in which a pigment is dispersed in a resin, resin-coated dispersions in which the surface of a pigment is coated with a resin, and self-dispersing pigments in which a hydrophilic group is provided on the pigment surface, but water-dispersible pigments are preferred. Among these, resin-coated pigments or self-dispersing pigments that have at least one hydrophilic group on the pigment surface are preferred. Examples of such hydrophilic groups include -COOM, -SO3M, -PO3HM, -PO3M2, -CONM2, -SO3NM2, -NH-C6H4-COOM, -NH-C6H4-SO3M, -NH-C6H4-PO3HM, -NH-C6H4-PO3M2, -NH-C6H4-CONM2, -NH-C6H4-SO3NM2, etc. These hydrophilic groups can be introduced by known methods.

[0071] Furthermore, the counter ion M is preferably a quaternary ammonium ion. Specific examples thereof include tetramethylammonium ion, tetraethylammonium ion, tetrapropylammonium ion, tetrabutylammonium ion, tetrapentylammonium ion, benzyltrimethylammonium ion, benzyltriethylammonium ion, and tetrahexylammonium ion. Among these, tetraethylammonium ion, tetrabutylammonium ion, and benzyltrimethylammonium ion are preferred, with tetrabutylammonium ion being particularly preferred. Inks using the above pigments have particularly high storage stability and suppress an increase in viscosity when water evaporates. This is presumably because the hydrophilic group containing the quaternary ammonium ion allows the pigment dispersion to be kept stable even when the water evaporates from the water-rich ink and the ink becomes organic solvent-rich.

[0072] As a colorant other than the pigment having a hydrophilic group, a polymer emulsion containing a pigment in polymer particles is preferred. The pigment may be encapsulated in the polymer particles or adsorbed on the surface of the polymer particles. In this case, it is not necessary for all the pigment to be encapsulated or adsorbed; a portion may be dispersed in the emulsion. Examples of polymers for the polymer particles include vinyl polymers, polyester polymers, and polyurethane polymers, with vinyl polymers and polyester polymers being particularly preferred. Specific examples include those disclosed in JP-A-2000-53897 and JP-A-2001-139849.

[0073] Alternatively, a composite pigment in which particles of a general organic pigment or inorganic pigment are coated with an organic pigment or carbon black can be used. The composite pigment can be prepared by a method in which an organic pigment is precipitated in the presence of inorganic pigment particles, or by a mechanochemical method in which an inorganic pigment and an organic pigment are mechanically mixed and ground. Furthermore, if necessary, a layer of an organosilane compound generated from a polysiloxane or an alkylsilane can be provided between the inorganic pigment and the organic pigment to improve adhesion between them. The mass ratio of the inorganic pigment particles to the organic pigment or carbon black colorant is preferably 3:1 to 1:3, and more preferably 3:2 to 1:2. When the content of the colorant is within the above range, the color development and coloring power are not reduced, and the transparency and color tone are not deteriorated. As the composite pigment, silica / carbon black composite material, silica / phthalocyanine PB15:3 composite material, silica / disazo yellow composite material, silica / quinacridone PR122 composite material, and the like manufactured by Toda Kogyo Co., Ltd. are suitable because they have small average primary particle diameters.

[0074] If inorganic pigment particles with a primary particle diameter of 20 nm are coated with an equal amount of organic pigment, the resulting primary particle diameter will be approximately 25 nm. If an appropriate dispersant can be used to disperse these particles down to the primary particle size, it will be possible to produce an extremely fine pigment dispersion ink with a dispersed particle diameter of 25 nm. In this composite pigment, not only does the organic pigment on the surface contribute to dispersion, but the properties of the inorganic pigment at the center also emerge through a thin layer of organic pigment approximately 2.5 nm thick. Therefore, it is important to select a pigment dispersant that can simultaneously stabilize the dispersion of both.

[0075] Examples of the inorganic pigment include titanium oxide, iron oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, cadmium red, chrome yellow, carbon black, etc. Among these, carbon black is preferred. Examples of the carbon black include channel black, furnace black, gas black, and lamp black, which are produced by known methods such as a contact method, a furnace method, and a thermal method.

[0076] Examples of the organic pigments include azo pigments, polycyclic pigments, dye chelates, nitro pigments, nitroso pigments, and aniline black. Among these, azo pigments and polycyclic pigments are preferred. Examples of the azo pigments include azo lakes, insoluble azo pigments, condensed azo pigments, and chelate azo pigments. Examples of the polycyclic pigments include phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, indigo pigments, thioindigo pigments, isoindolinone pigments, and quinophthalone pigments. Examples of the dye chelate include basic dye chelates and acid dye chelates.

[0077] Examples of the organic pigment include CI Pigment Yellow 1, 3, 12, 13, 14, 17, 24, 34, 35, 37, 42 (yellow iron oxide), 53, 55, 74, 81, 83, 95, 97, 98, 100, 101, 104, 408, 109, 110, 117, 120, 128, 139, 150, 151, 155, 153, 180, 183, 185, 213, CI Pigment Orange 5, 13, 16, 17, 36, 43, 51, CI Pigment Red 1, 2, 3, 5, 17, 22, 23, 31, 38, 48:2 (Permanent Red 2B (Ca)), 48:3, 48:4, 49:1, 52:2, 53:1, 57:1 (Brilliant Carmine 6B), 60:1, 63 :1, 63:2, 64:1, 81, 83, 88, 101 (Red Iron), 104, 105, 106, 108 (Cadmium Red), 112, 114, 122 (Quinacridone Magenta), 123, 146, 149, 166, 168, 170, 172, 177, 178, 179, 185, 190, 193, 209, 219, CI Pigment Rhodamine Lake 1 (Rhodamine Lake), 3, 5:1, 16, 19, 23, 38; CI Pigment Blue 1, 2, 15 (Phthalocyanine Blue), 15:1, 15:2, 15:3 (Phthalocyanine Blue), 16, 17:1, 56, 60, 63; CI Pigment Green 1, 4, 7, 8, 10, 17, 18, 36, etc.

[0078] The BET specific surface area of ​​the pigment is 10m 2 / g or more 1500m 2 / g or less is preferable, and 20m 2 / g or more 600m 2 / g or less is more preferable, and 50m 2 / g or more 300m 2 / g or less is more preferable. If the desired BET specific surface area is not readily available, the pigment can be subjected to conventional size reduction or milling processes (e.g., ball milling, jet milling, ultrasonication) to reduce the particle size to a relatively small particle size. Cumulative 50% volume particle diameter D of the colorant 50 In the ink, the particle size is preferably 10 nm or more and 200 nm or less. The content of the colorant is preferably 1% by mass or more and 15% by mass or less, and more preferably 1.5% by mass or more and 10% by mass or less, based on the total amount of the ink, in terms of solid content. If the content of the colorant is 1% by mass or more, the color development and image density of the ink are improved, and if it is 15% by mass or less, the ink does not thicken and the ejection properties do not deteriorate, and is also economically preferable. In the present invention, dyes may be used in combination for the purpose of adjusting the color tone, but they must be used within a range that does not deteriorate the weather resistance.

[0079] <Water> As the water, for example, pure water such as ion-exchanged water, ultrafiltered water, reverse osmosis water, distilled water, or ultrapure water can be used. The water content in the ink is not particularly limited and can be selected appropriately depending on the purpose. From the viewpoint of the drying property and ejection reliability of the ink, however, it is preferably 10% by mass or more and 90% by mass or less, and more preferably 20% by mass or more and 60% by mass or less.

[0080] The ink preferably further contains a surfactant. <Surfactant> In the present invention, in order to reduce the dynamic surface tension of the ink at 25°C after a surface life of 15 msec as measured by the maximum bubble pressure method to 34.0 mN / m or less and maintain the static surface tension of the ink at 25°C to 20.0 mN / m or more, it is preferable to use at least one of a polyether-modified siloxane compound, an acetylene glycol surfactant, and an acetylene alcohol surfactant. This makes the ink less likely to wet the ink-repellent film on the head nozzle plate, preventing ejection defects due to ink adhesion to the nozzles and improving ejection stability. Furthermore, the ink is less likely to adhere to the ink-repellent film surface of the nozzle, which is a particularly problematic surface, and is therefore less likely to cause ejection defects.

[0081] Among polyether-modified siloxane compounds, those represented by the following general formulas (IV) to (VII) are preferred, and in particular, those that do not impair dispersion stability depending on the type of water-dispersible colorant or the combination with an organic solvent, have low dynamic surface tension, and have high penetration and leveling properties are preferred. These surfactants may be used alone or in combination of two or more.

[0082] [ka] In the general formula (IV), R represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, m represents an integer of 0 to 23, n represents an integer of 1 to 10, a represents an integer of 1 to 23, and b represents an integer of 0 to 23.

[0083] [ka] In the general formula (V), R2 and R3 each represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, m represents an integer of 1 to 8, and c and d represent integers of 1 to 10.

[0084] [ka] In the general formula (VI), R4 represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and e represents an integer of 1 to 8.

[0085] [ka] In the general formula (VII), R5 represents a polyether group of the following general formula (C), and f represents an integer of 1 to 8.

[0086] [ka] In the general formula (C), R6 represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, g represents an integer of 0 to 23, and h represents an integer of 0 to 23, excluding cases where g and h are 0 at the same time.

[0087] Examples of the compound represented by the general formula (IV) include compounds represented by the following formulas (7) to (14).

[0088] [ka]

[0089] [ka]

[0090] [ka]

[0091] [ka]

[0092] [ka]

[0093] JPEG0007739786000034.jpg42165

[0094] [ka]

[0095] [ka]

[0096] Examples of the compound represented by the general formula (V) include a compound represented by the following formula (15).

[0097] [ka]

[0098] Examples of the compound represented by the general formula (VI) include a compound represented by the following formula (16).

[0099] [ka]

[0100] Examples of the compound represented by the general formula (VII) include compounds represented by the following formulae (17) to (19). [ka]

[0101] [ka]

[0102] [ka]

[0103] Furthermore, examples of commercially available polyether-modified siloxane compounds that exhibit effects equivalent to those of the above compounds include 71ADDITIVE, 74ADDITIVE, 57ADDITIVE, 8029ADDITIVE, 8054ADDITIVE, 8211ADDITIVE, 8019ADDITIVE, 8526ADDITIVE, FZ-2123, and FZ-2191 manufactured by TORAY Dow Corning; TSF4440, TSF4441, TSF4445, TSF4446, TSF4450, TSF4452, and TSF4460 manufactured by Momentive Performance Materials; Silface SAG002, Silface SAG003, Silface SAG005, Silface SAG503A, Silface SAG008, and Silface SJM003 manufactured by Nissin Chemical Industry Co., Ltd.; and TEGO® manufactured by Evonik. WetKL245, TEGO Wet250, TEGO Wet260, TEGO Wet265, TEGO Wet270, TEGO Wet280; BYK-345, BYK-347, BYK-348, BYK-375, BYK-377 manufactured by BYK Japan;

[0104] As the acetylene glycol surfactant or acetylene alcohol surfactant, commercially available products can be used, and examples of the commercially available products include Surfynol 104, Surfynol 104E, Surfynol 420, Surfynol 440, Surfynol 465, Surfynol SE, Surfynol SEF, Surfynol PSA-336, Surfynol DF110D, Surfynol DF58, Olfine E1004, Olfine E1010, Olfine E1020, Olfine PD-001, Olfine PD-002W, Olfine PD-004, Olfine PD-005, Olfine EXP. 4001, Olfine EXP. 4200, Olfine EXP. 4123, and Olfine EXP. 4300 (all manufactured by Nissin Chemical Industry Co., Ltd.). Furthermore, if necessary, fluorine-based surfactants, silicone-based surfactants, and the like other than the above-mentioned polyether-modified siloxane compounds, acetylene glycol surfactants, and acetylene alcohol surfactants may be used in combination.

[0105] The content of the surfactant is preferably 0.001% by mass or more and 5% by mass or less, and more preferably 0.5% by mass or more and 3% by mass or less, based on the total amount of ink. If the content is 0.001% by mass or more, a good effect of adding the surfactant can be obtained. However, if the content exceeds 5% by mass, the effect of adding the surfactant becomes saturated, and there is no point in increasing the amount.

[0106] -Other ingredients- As the other components, various known additives may be further added as needed, such as a foam inhibitor (antifoaming agent), a pH adjuster, an antiseptic / fungal agent, a chelating agent, a rust inhibitor, an antioxidant, an ultraviolet absorber, an oxygen absorber, and a light stabilizer.

[0107] -Foam suppressor- Foam suppressors are added in minute amounts to ink to suppress foaming. Foaming refers to a liquid forming a thin film that encases air. The formation of this foam is influenced by ink characteristics such as surface tension and viscosity. Liquids with high surface tension, such as water, are less likely to foam because of the forces that try to minimize the surface area of ​​the liquid. In contrast, inks with high viscosity and high permeability tend to foam easily because of their low surface tension, but the viscosity of the solution makes it easier for the foam to form and maintain its shape, making it difficult for it to disappear.

[0108] Typically, foam suppressors destroy bubbles by locally lowering the surface tension of the foam film, or by dotting the surface of the foaming liquid with foam suppressors that are insoluble in the foaming liquid. When a polyether-modified siloxane compound surfactant, which has a very strong surface tension-reducing effect, is used in the ink, the use of a foam suppressor that works by the former mechanism does not result in a localized reduction in the surface tension of the foam film. Therefore, foam suppressors that are insoluble in the foaming liquid are used, but in this case, the stability of the ink is reduced by the foam suppressor being insoluble in the solution. In contrast, the foam suppressor of the following general formula (IX) does not have as strong a surface tension reducing effect as the polyether-modified siloxane compound surfactant, but it is highly compatible with the surfactant. For this reason, the foam suppressor is efficiently incorporated into the foam film, and the difference in surface tension between the surfactant and the foam suppressor causes the surface of the foam film to become locally unbalanced, which is thought to result in the collapse of the foam.

[0109] [ka] In the general formula (IX), R7 and R8 each independently represent an alkyl group having 3 to 6 carbon atoms; R9 and R 10 each independently represents an alkyl group having 1 to 2 carbon atoms, and n represents an integer of 1 to 6.

[0110] Examples of the compound represented by general formula (IX) include 2,4,7,9-tetramethyldecane-4,7-diol and 2,5,8,11-tetramethyldodecane-5,8-diol. 2,5,8,11-tetramethyldodecane-5,8-diol is particularly preferred due to its anti-foaming effect and high compatibility with ink. The content of the anti-foaming agent in the ink is preferably 0.01% by mass to 10% by mass, more preferably 0.1% by mass to 5% by mass. If the content is 0.01% by mass, the anti-foaming effect is obtained, and if it is 10% by mass or less, the anti-foaming effect does not plateau and there is no adverse effect on ink properties such as viscosity and particle size.

[0111] - pH adjuster - The pH adjuster is not particularly limited as long as it can adjust the pH to 7 to 11 without adversely affecting the ink being formulated, and can be appropriately selected depending on the purpose. Examples of the pH adjuster include alcohol amines, hydroxides of alkali metal elements, hydroxides of ammonium, phosphonium hydroxides, and carbonates of alkali metals. If the pH is outside the range of 7 to 11, the inkjet head and ink supply unit will be dissolved to a large extent, which may cause problems such as ink deterioration, leakage, and ejection failure.

[0112] Examples of the alcohol amines include diethanolamine, triethanolamine, and 2-amino-2-ethyl-1,3 propanediol. Examples of the hydroxides of alkali metal elements include lithium hydroxide, sodium hydroxide, and potassium hydroxide. Examples of the hydroxide of ammonium include ammonium hydroxide and quaternary ammonium hydroxide. Examples of the phosphonium hydroxide include quaternary phosphonium hydroxide. Examples of the alkali metal carbonate include lithium carbonate, sodium carbonate, and potassium carbonate. As the pH adjuster, a strongly basic compound is preferably used, more preferably potassium hydroxide or sodium hydroxide, and 2-amino-2-ethyl-1,3 propanediol is also preferably used.

[0113] -Preservative and fungicidal agent- Examples of antiseptic and antifungal agents include sodium dehydroacetate, sodium sorbate, sodium 2-pyridinethiol-1-oxide, sodium benzoate, and sodium pentachlorophenol.

[0114] -Chelating reagents- Examples of the chelating agent include sodium ethylenediaminetetraacetate, sodium nitrilotriacetate, sodium hydroxyethylethylenediaminetriacetate, sodium diethylenetriaminepentaacetate, and sodium uramildiacetate.

[0115] -Rust inhibitor- Examples of the rust inhibitor include acid sulfite, sodium thiosulfate, ammonium thiodiglycolate, diisopropylammonium nitrite, pentaerythritol tetranitrate, and dicyclohexylammonium nitrite.

[0116] -Antioxidants- Examples of antioxidants include phenol-based antioxidants (including hindered phenol-based antioxidants), amine-based antioxidants, sulfur-based antioxidants, and phosphorus-based antioxidants.

[0117] -Ultraviolet absorber- Examples of the ultraviolet absorber include benzophenone-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, salicylate-based ultraviolet absorbers, cyanoacrylate-based ultraviolet absorbers, and nickel complex salt-based ultraviolet absorbers.

[0118] <Ink manufacturing> The ink of the present invention can be produced by a stirring and mixing step of dispersing or dissolving an anionic compound, an organic solvent, water, a photoacid generator, and optionally a colorant and other components in an aqueous medium, followed by stirring and mixing, and then heating the resulting mixture at 40°C or higher but lower than 70°C for 6 hours or longer. This stirring and mixing can be carried out using, for example, a sand mill, a homogenizer, a ball mill, a paint shaker, an ultrasonic disperser, or the like, and the stirring and mixing can be carried out using a conventional stirrer with stirring blades, a magnetic stirrer, a high-speed disperser, or the like.

[0119] <Ink properties> The physical properties of the ink of the present invention are not particularly limited and can be appropriately selected depending on the purpose. However, if the static surface tension of the ink is 20 mN / m or more and the dynamic surface tension at a bubble lifetime of 15 msec as measured by the maximum bubble pressure method is 34 mN / m or less, it is possible to ensure sufficient wettability to the recording medium, but the ink will not easily wet the water-repellent film on the nozzle plate of the inkjet head, and ejection stability can be ensured, resulting in an extremely stable ink, which is preferable. Furthermore, the viscosity of the ink at 25°C is preferably 5 mPa·s or more and 25 mPa·s or less, and more preferably 6 mPa·s or more and 20 mPa·s or less. If the viscosity is 5 mPa·s or more, the image density and character quality can be improved. If the viscosity is 25 mPa·s or less, ink ejection properties can be ensured. The viscosity can be measured at 25°C using, for example, a viscometer (RE-85L, manufactured by Toki Sangyo Co., Ltd.). In order to ensure ink storage stability, the pH is preferably 8 to 10, and more preferably 8.5 to 10.

[0120] (ink set) The ink set of the present invention is an ink set having at least two inks selected from a cyan ink, a magenta ink, a yellow ink, and a black ink, The inks constituting the ink set are the inks of the present invention. When recording is performed using an ink set that uses two or more of the above colors in combination, a multicolor image can be formed, and when recording is performed using an ink set that uses all of the above colors in combination, a full-color image can be formed.

[0121] (ink container) The ink of the present invention may be used by being contained in a container such as an ink cartridge. The ink container of the present invention contains the ink of the present invention in a container that has been treated to block ultraviolet light. Examples of ultraviolet light blocking treatment include an ink pack made of aluminum laminated film or aluminum vapor-deposited film filled with ink, and a plastic container (ink cartridge) with carbon black or the like kneaded into it.

[0122] <Recording Media> There are no particular limitations on the recording media on which recording can be performed using the ink of the present invention, and they can be appropriately selected depending on the purpose, and examples include plain paper, glossy paper, special paper, cloth, film, OHP sheets, general-purpose printing paper, etc. However, the ink of the present invention is extremely advantageous in that it can print as well on non-permeable media for signage and commercial printing paper as on other papers.

[0123] The ink of the present invention is capable of forming good images even when using non-permeable or poorly permeable media. Impermeable or poorly permeable media are substrates with surfaces that are low in water permeability and absorbency, and include materials that have many cavities inside but are not open to the outside. More quantitatively, in the Bristow method, 1 / 2 Water absorption up to 10mL / m 2 The substrate is As the impermeable or poorly permeable medium, for example, plastic films such as vinyl chloride resin film, polyethylene terephthalate (PET) film, polypropylene film, polyethylene film, and polycarbonate film can be suitably used.

[0124] <Printed material> Printed matter bearing an image formed using the ink of the present invention has high image quality, is free from bleeding, and has excellent stability over time, and can be suitably used for a variety of purposes, such as documents on which various types of printing or images are recorded.

[0125] (Printing method and printing device) The printing method of the present invention includes an application step and an ultraviolet light irradiation step, and may further include other steps as necessary.

[0126] The printing device of the present invention comprises an applying means and an ultraviolet light irradiating means, and further comprises other means as required.

[0127] <Application step and application means> The application step is a step of applying the ink of the present invention onto a recording medium, and is carried out by an application means. The method for applying the ink is not particularly limited, and examples thereof include inkjet method, blade coating method, gravure coating method, gravure offset coating method, bar coating method, roll coating method, knife coating method, air knife coating method, comma coating method, U comma coating method, AKKU coating method, smoothing coating method, microgravure coating method, reverse roll coating method, four-roll coating method, five-roll coating method, dip coating method, curtain coating method, slide coating method, die coating method, etc. Among these, the inkjet method is preferably used.

[0128] <Ultraviolet Light Irradiation Step and Ultraviolet Light Irradiation Means> The ultraviolet light irradiation step is a step of irradiating the ink with ultraviolet light after application, and is carried out by an ultraviolet light irradiation means. The ultraviolet light irradiation means includes an ultraviolet lamp that emits ultraviolet light in a specific wavelength range with stable exposure energy, and a filter that transmits ultraviolet light of the specific wavelength. Examples of the ultraviolet lamp that can be used include a mercury lamp, a metal halide lamp, an electrodeless lamp, an excimer laser, an ultraviolet laser, a cold cathode tube, a hot cathode tube, a black light, and an LED (light emitting diode). Of these, a strip-shaped metal halide lamp, a cold cathode tube, a hot cathode tube, a mercury lamp, or a black light is preferred. The amount of ultraviolet light irradiation is preferably 1 mJ or more and 3,000 mJ or less, and more preferably 500 mJ or more and 2,000 mJ or less.

[0129] <Other steps and other means> Other steps include, for example, a drying step. Other means include, for example, drying means.

[0130] <Recording device and recording method> The ink of the present invention can be suitably used in various recording devices using the ink jet recording method, such as printers, facsimile machines, copying machines, printer / fax / copier combination machines, and three-dimensional modeling devices. In the present invention, the term "recording apparatus" and "recording method" refer to an apparatus capable of ejecting ink or various treatment liquids onto a recording medium, and a method of recording using the apparatus. The term "recording medium" refers to an object onto which ink or various treatment liquids can be attached, even if only temporarily.

[0131] This recording device can include not only the head portion that ejects ink, but also means related to feeding, transporting, and discharging the recording medium, as well as other devices called pre-processing devices and post-processing devices. The recording apparatus and recording method may have a heating means used in the heating step and a drying means used in the drying step. The heating means and drying means include, for example, means for heating and drying the image side or back side of the recording medium. The heating means and drying means are not particularly limited, but the recording medium can be dried using, for example, an infrared drying device, a microwave drying device, a roll heater, a drum heater, or hot air. Heating and drying can be performed before, during, or after printing. Furthermore, it is preferable to irradiate with ultraviolet (UV) light simultaneously with heating and drying. Furthermore, the recording device and recording method are not limited to those that visualize meaningful images such as letters and figures using ink. For example, they also include those that form patterns such as geometric designs and those that create three-dimensional images. Furthermore, unless otherwise specified, the recording apparatus includes both a serial type apparatus in which the ejection head moves and a line type apparatus in which the ejection head does not move. Furthermore, this recording device includes not only desktop types, but also wide-width recording devices that can print on A0-sized recording media, and continuous feed printers that can use, for example, continuous paper wound into a roll as a recording medium.

[0132] Here, FIG. 1 is a schematic front view showing an example of an inkjet recording device which is a printing device of the present invention, FIG. 2 is a schematic side view showing an example of an inkjet recording device which is a printing device of the present invention, and FIG. 3 is a schematic view showing the configuration of the main parts of the inkjet recording device, which is an example of a device in which the main parts of a RICOH Pro L4160 (manufactured by Ricoh Company, Ltd.) have been partially modified. The inkjet recording apparatus 1 shown in FIGS. 1 to 3 comprises a head carriage 2, a recording head 3, an ink ejection unit 6, an ultraviolet ray irradiation means 4, a platen and a heater unit 5. In this inkjet recording apparatus 1, a platen and a heater unit 5 are installed below the recording medium S.

[0133] The recording medium S is guided by the platen and heater unit 5, and is moved from the front to the back in FIG. 3 by the operation of a transport means (not shown). A head scanning means (not shown) moves the head carriage 2 back and forth in the direction L in FIG. 3, thereby scanning the recording head 3 held by the head carriage 2.

[0134] The head carriage 2 is installed above the recording medium S, and accommodates a plurality of recording heads 3 (described later) according to the number of colors used to print an image on the recording medium S, with ejection openings arranged below. The head carriage 2 is installed on the main body of the recording apparatus 1 so as to be able to reciprocate in the direction L in FIG. 3, and is driven by the head scanning means to reciprocate in the direction L in FIG.

[0135] In Figure 3, the head carriage 2 is illustrated as housing recording heads 3 of yellow (Y), magenta (M), cyan (C), and black (K), but in practice the number of colors of recording heads 3 housed in the head carriage 2 can be determined appropriately.

[0136] The recording head 3 ejects ink supplied by ink supply means (not shown) from the ink ejection section 6 toward the recording medium S by the operation of a plurality of ejection means (not shown) provided inside. The ink ejected from the recording head 3 is composed of anionic compounds, organic solvents, water, photoacid generators, etc. When exposed to ultraviolet light, the photoacid generator generates an acid (cation), which acts on the anionic compound, causing the anionic resin or anionic pigment to aggregate and thicken, thereby suppressing beading and color bleeding.

[0137] During the scanning movement of the recording head 3 from one end of the recording medium S to the other end of the recording medium S in the L direction in Figure 3, driven by the head scanning means, ink is ejected as ink droplets onto a certain area (landing area) on the recording medium S, causing the ink droplets to land in the landing area.

[0138] After the above scan is performed an appropriate number of times and ink is ejected toward one possible landing area, the recording medium S is moved appropriately from the front to the back in Figure 3 using the transport means, and while scanning is performed again using the head scanning means, ink is ejected by the recording head 3 toward the next possible landing area adjacent to the above possible landing area in the back direction in Figure 3.

[0139] By repeating the above operation and ejecting ink from the recording head 3 in conjunction with the head scanning means and the transport means, an image made up of a collection of ink droplets is formed on the recording medium S.

[0140] The ultraviolet irradiation means 4 is configured to include an ultraviolet lamp that emits ultraviolet light in a specific wavelength range with stable exposure energy, and a filter that transmits ultraviolet light of the specific wavelength. Examples of ultraviolet lamps that can be used include mercury lamps, metal halide lamps, electrodeless lamps, excimer lasers, ultraviolet lasers, cold cathode tubes, hot cathode tubes, black lights, and LEDs (light emitting diodes). Of these, strip-shaped metal halide lamps, cold cathode tubes, hot cathode tubes, mercury lamps, and black lights are preferred. The amount of ultraviolet light irradiation is preferably 1 mJ or more and 3,000 mJ or less, and more preferably 500 mJ or more and 2,000 mJ or less.

[0141] It is preferable to have a filter in the ink flow path from the ink storage unit (ink cartridge) 410 shown in Fig. 4 to the recording head 3 attached to the inkjet recording apparatus 1 shown in Fig. 3. Alternatively, a filter may be provided in the ink supply / discharge unit 412. The filter is preferably one that can retain particles with a particle size of 10 µm or more, and by providing a filter, it is possible to remove particles with a particle size of 10 µm or more, thereby providing a printing apparatus with excellent ejection stability. Since the filter is constantly in contact with ink, it is preferably made of stainless steel from the viewpoint of corrosion resistance, and among these, austenitic stainless steel, particularly SUS304, SUS316, or SUS316L, is preferred because of its excellent corrosion resistance. Note that the filter preferably contains any one selected from SUS304, SUS316, and SUS316L.

[0142] Filters with different filtration accuracy are commercially available, and for example, an Acro Last Chance filter manufactured by Nippon Pall Corporation can be used. Using a filter with a filtration accuracy of 10 μm or less is preferred because it can remove solids present in the ink and improve ejection stability. Using a filter with a filtration accuracy of 6 μm or more and 10 μm or less is preferred because it allows ink to be supplied to the ejection means in an optimal manner. Specific products include, for example, disposable filters with a filtration accuracy of 10 μm, and PALL ACRO25 LCF-12100, with a filtration accuracy of 10 μm and made of polypropylene.

[0143] In addition, in the present invention, the terms image formation, recording, printing, printing, etc. are all synonymous. Recording medium, media, and printed material are all synonymous terms. [Example]

[0144] Examples of the present invention will be described below, but the present invention is not limited to these examples in any way.

[0145] (Preparation Example 1) -Preparation of surface-modified black pigment dispersion- Cabot Corporation's Black Pearls (registered trademark) 1000 (BET specific surface area 343 m 2100 g of carbon black (carbon black with a dibutyl phthalate absorption capacity of 105 mL / 100 g, dibutyl phthalate absorption capacity (DBPA) of 105 mL / 100 g), 100 mmol of sulfanilic acid, and 1 L of ion-exchanged high-purity water were mixed at room temperature in a Silverson mixer (6,000 rpm). Next, 100 mmol of nitric acid was added to the resulting slurry, and after a further 30 minutes, sodium nitrite (100 mmol) dissolved in 10 mL of ion-exchanged high-purity water was slowly added. The mixture was then heated to 60°C with stirring and reacted for 1 hour to obtain a modified pigment in which sulfanilic acid was attached to carbon black. Next, the pH was adjusted to 9 with a 10% by mass tetrabutylammonium hydroxide solution (methanol solution), and after 30 minutes, a modified pigment dispersion was obtained. Next, this dispersion and ion-exchanged high-purity water were subjected to ultrafiltration using a dialysis membrane, and further ultrasonic dispersion was performed to obtain a surface-modified black pigment dispersion containing 20% ​​by mass of pigment solids. The surface treatment level of the pigment in the obtained surface-modified black pigment dispersion was 0.75 mmol / g, and when measured using a particle size distribution analyzer (Nanorakku UPA-EX150, manufactured by Nikkiso Co., Ltd.), the cumulative 50% volume particle diameter D 50 was 120 nm.

[0146] (Preparation Example 2) -Preparation of surface-modified magenta pigment dispersion- 1 kg of a pigment dispersion SMART Magenta 3122BA (surface-treated dispersion of Pigment Red 122, pigment solid content 14.5% by mass) manufactured by SENSIENT was subjected to acid precipitation with a 0.1 N HCl aqueous solution. Next, the pH was adjusted to 9 with a 10% by mass aqueous solution of tetraethylammonium hydroxide, and after 30 minutes, a modified pigment dispersion was obtained. The modified pigment dispersion containing a pigment bonded to at least one aminobenzoic acid group or aminobenzoic acid tetraethylammonium salt was subjected to ultrafiltration using a dialysis membrane with ion-exchanged highly pure water, and further ultrasonic dispersion was performed to obtain a surface-modified magenta pigment dispersion containing 20% ​​by mass of pigment solids. The obtained surface-modified magenta pigment dispersion was measured using a particle size distribution analyzer (Nanorakku UPA-EX150, manufactured by Nikkiso Co., Ltd.). The cumulative 50% volume particle diameter D 50 was 104 nm.

[0147] (Preparation Example 3) -Preparation of surface-modified cyan pigment dispersion- 1 kg of a pigment dispersion SMART Cyan 3154BA (Pigment Blue 15:4 surface-treated dispersion, pigment solid content 14.5% by mass) manufactured by SENSIENT was subjected to acid precipitation with a 0.1 N HCl aqueous solution. Next, the pH was adjusted to 9 with a 40% by mass benzyltrimethylammonium hydroxide solution (methanol solution), and after 30 minutes, a modified pigment dispersion was obtained. The modified pigment dispersion containing a pigment bonded to at least one aminobenzoic acid group or aminobenzoic acid benzyltrimethylammonium salt was subjected to ultrafiltration using a dialysis membrane with ion-exchanged high-purity water, and further ultrasonic dispersion was performed to obtain a surface-modified cyan pigment dispersion containing 20% ​​by mass of pigment solids. The obtained surface-modified cyan pigment dispersion was measured using a particle size distribution analyzer (Nanotrac UPA-EX150, manufactured by Nikkiso Co., Ltd.). The cumulative 50% volume particle diameter D 50 was 116 nm.

[0148] (Preparation Example 4) -Preparation of surface-modified yellow pigment dispersion- 1 kg of SENSIENT SMART Yellow 3074BA pigment dispersion (surface-treated Pigment Yellow 74 dispersion, pigment solids content 14.5% by mass) was adjusted to pH 9 with a 10% by mass tetrabutylammonium hydroxide solution (methanol solution), and left for 30 minutes to yield a modified pigment dispersion. The modified pigment dispersion, containing a pigment bonded to at least one aminobenzoic acid group or aminobenzoic acid tetrabutylammonium salt, was subjected to ultrafiltration using a dialysis membrane with ion-exchanged high-purity water, followed by ultrasonic dispersion to yield a surface-modified yellow pigment dispersion containing 20% ​​pigment solids. The obtained surface-modified yellow pigment dispersion was measured using a particle size distribution analyzer (Nanotrac UPA-EX150, manufactured by Nikkiso Co., Ltd.). The cumulative 50% volume particle diameter D 50 was 145 nm.

[0149] (Preparation Example 5) <Preparation of Polymer Solution A> After thoroughly replacing the air in a 1 L flask equipped with a mechanical stirrer, thermometer, nitrogen gas inlet tube, reflux condenser, and dropping funnel with nitrogen, 11.2 g of styrene, 2.8 g of acrylic acid, 12.0 g of lauryl methacrylate, 4.0 g of polyethylene glycol methacrylate, 4.0 g of styrene macromer, and 0.4 g of mercaptoethanol were mixed and heated to 65 ° C. Next, a mixed solution of 100.8 g of styrene, 25.2 g of acrylic acid, 108.0 g of lauryl methacrylate, 36.0 g of polyethylene glycol methacrylate, 60.0 g of hydroxylethyl methacrylate, 36.0 g of styrene macromer, 3.6 g of mercaptoethanol, 2.4 g of azobismethylvaleronitrile, and 18 g of methyl ethyl ketone was added dropwise to the flask over 2.5 hours. After the dropwise addition, a mixed solution of 0.8 g of azobismethylvaleronitrile and 18 g of methyl ethyl ketone was added dropwise to the flask over 0.5 hours. After aging for 1 hour at 65°C, 0.8 g of azobismethylvaleronitrile was added and aging was continued for another 1 hour. After the reaction was completed, 364 g of methyl ethyl ketone was added to the flask, and 800 g of polymer solution A with a concentration of 50% by mass was obtained.

[0150] -Preparation of magenta pigment-containing polymer particle dispersion- 28 g of the polymer solution A, 42 g of CI Pigment Red 122, 13.6 g of a 1 mol / L potassium hydroxide aqueous solution, 20 g of methyl ethyl ketone, and 13.6 g of ion-exchanged water were thoroughly stirred and then kneaded using a roll mill. The resulting paste was added to 200 g of pure water and thoroughly stirred. The methyl ethyl ketone and water were then distilled off using an evaporator. Furthermore, to remove coarse particles, the resulting dispersion was pressure-filtered through a polyvinylidene fluoride membrane filter with an average pore size of 5.0 μm, yielding a magenta pigment-containing polymer microparticle dispersion containing 15% by weight of pigment and 20% by weight of solids. The obtained magenta pigment-containing polymer particle dispersion was measured using a particle size distribution analyzer (Nanotrac UPA-EX150, manufactured by Nikkiso Co., Ltd.). The cumulative 50% volume particle diameter D 50 was 127 nm.

[0151] (Preparation Example 6) -Preparation of cyan pigment-containing polymer particle dispersion- A cyan pigment-containing polymer fine particle dispersion was prepared in the same manner as in Preparation Example 5, except that CI Pigment Red 122 used in Preparation Example 5 was changed to a phthalocyanine pigment (CI Pigment Blue 15:3). The polymer particles in the obtained cyan pigment-containing polymer particle dispersion were measured using a particle size distribution analyzer (Nanotrac UPA-EX150, manufactured by Nikkiso Co., Ltd.). The cumulative 50% volume particle diameter D 50 was 93 nm.

[0152] (Preparation Example 7) -Preparation of yellow pigment-containing polymer particle dispersion- A yellow pigment-containing polymer fine particle dispersion was prepared in the same manner as in Preparation Example 5, except that CI Pigment Red 122 used in Preparation Example 5 was changed to a bisazo yellow pigment (CI Pigment Yellow 155). The polymer particles in the obtained yellow pigment-containing polymer particle dispersion were measured using a particle size distribution analyzer (Nanotrac UPA-EX150, manufactured by Nikkiso Co., Ltd.). The cumulative 50% volume particle diameter D 50 was 76 nm.

[0153] (Preparation Example 8) -Preparation of polymer particle dispersion containing carbon black pigment- A carbon black pigment-containing polymer fine particle dispersion was prepared in the same manner as in Preparation Example 5, except that CI Pigment Red 122 used in Preparation Example 5 was replaced with carbon black (FW100, manufactured by Degussa). The polymer particles in the obtained carbon black pigment-containing polymer particle dispersion were measured using a particle size distribution analyzer (Nanotrac UPA-EX150, manufactured by Nikkiso Co., Ltd.). The cumulative 50% volume particle diameter D 50 was 104 nm.

[0154] (Resin particle preparation example 1) <Preparation of Water-Dispersible Polyurethane Resin (A)> -Synthesis of polyester polyol P-1- In a reaction vessel equipped with a thermometer, a nitrogen gas inlet tube, and a stirrer, 830 parts by mass of terephthalic acid, 830 parts by mass of isophthalic acid, 374 parts by mass of ethylene glycol, 598 parts by mass of neopentyl glycol, and 0.5 parts by mass of dibutyltin oxide were charged while introducing nitrogen gas, and a polycondensation reaction was carried out at 230°C for 15 hours at 180°C to 230°C until the acid value reached 1 mgKOH / g or less, yielding polyester polyol P-1 having a hydroxyl value of 74.5 mgKOH / g, an acid value of 0.2 mgKOH / g, and an average molecular weight of 1,500.

[0155] -Synthesis of Hydrophobic Polyester Polyol Q-1- In a reaction vessel equipped with a thermometer, a nitrogen gas inlet tube, and a stirrer, 1,660 parts by mass of orthophthalic acid, 1,637 parts by mass of diethylene glycol, and 0.5 parts by mass of dibutyltin oxide were charged while introducing nitrogen gas, and a polycondensation reaction was carried out at 230°C for 15 hours at 180°C to 230°C until the acid value reached 1 mgKOH / g or less, yielding polyester polyol Q-1 having an aromatic cyclic structure with a hydroxyl value of 190 mgKOH / g and an acid value of 0.3 mgKOH / g.

[0156] -Preparation of water-dispersible polyurethane resin (A)- 1,000 parts by mass of polyester polyol P-1 was dehydrated at 100°C under reduced pressure, then cooled to 80°C, and 907 parts by mass of methyl ethyl ketone was added, thoroughly stirred to dissolve, and 80 parts by mass of 2,2'-dimethylolpropionic acid was added. Next, 281 parts by mass of isophorone diisocyanate was added and reacted for 8 hours at 75° C. to carry out the urethane-forming step. After confirming that the isocyanate value had reached 0.1% by mass or less, the mixture was cooled to 50° C., and 340 parts by mass of the polyester polyol Q-1 was added to obtain a homogeneous solution. After neutralizing the solution with 60 parts by mass of triethylamine, the solution was solubilized by adding 7,000 parts by mass of water. Methyl ethyl ketone was removed from the resulting transparent reaction product under reduced pressure at 40 to 60°C, and then water was added to adjust the concentration to obtain a stable translucent colloidal aqueous dispersion with a nonvolatile content of 25% by mass.

[0157] (Resin particle preparation example 2) <Preparation of Water-Dispersible Polyurethane Resin (B)> 1,000 parts by mass of the polyester polyol P-1 described above was dehydrated at 100°C under reduced pressure, then cooled to 80°C, and 907 parts by mass of methyl ethyl ketone was added, thoroughly stirred to dissolve, and 80 parts by mass of 2,2'-dimethylolpropionic acid was added. Next, 281 parts by mass of isophorone diisocyanate was added and reacted at 75°C for 8 hours to carry out urethane formation. After confirming that the isocyanate value was 0.1% by mass or less, the mixture was cooled to 50°C, neutralized by adding 60 parts by mass of triethylamine, and then solubilized by adding 7,000 parts by mass of water. The resulting transparent reaction product was heated under reduced pressure at 40°C to 60°C to remove methyl ethyl ketone, and then water was added to adjust the concentration, resulting in a stable, translucent, colloidal aqueous dispersion with a nonvolatile content of 25%.

[0158] (Resin particle preparation example 3) <Preparation of Water-Dispersible Polyurethane Resin (C)> -Synthesis of polyester polyol P-2- In a reaction vessel equipped with a thermometer, a nitrogen gas inlet tube, and a stirrer, 664 parts by mass of terephthalic acid, 631 parts by mass of isophthalic acid, 472 parts by mass of 1,4-butanediol, 447 parts by mass of neopentyl glycol, and 0.5 parts by mass of dibutyltin oxide were charged while introducing nitrogen gas, and esterification was carried out at 180°C to 230°C for 5 hours, followed by a polycondensation reaction at 230°C for 6 hours until the acid value reached 1 mgKOH / g or less. Next, the mixture was cooled to 120°C, and 321 parts by mass of adipic acid and 268 parts by mass of 2,2'-dimethylolpropionic acid were added. The mixture was then heated again to 170°C and reacted at this temperature for 20 hours to obtain a carboxyl-containing polyester polyol P-2 with an acid value of 46.5 mg KOH / g and a hydroxyl value of 59.8 mg KOH / g.

[0159] -Preparation of water-dispersible polyurethane resin (C)- 1,000 parts by mass of polyester polyol P-2 was dehydrated at 100°C under reduced pressure, then cooled to 80°C, and 812 parts by mass of methyl ethyl ketone was added, thoroughly stirred and dissolved, and 20 parts by mass of 1,4-butanediol was added. Next, 198 parts by mass of dicyclohexylmethane-4,4'-diisocyanate (hydrogenated MDI) was added, and the mixture was reacted for 8 hours at 75°C. After confirming that the isocyanate value had reached 0.1% by mass or less, the mixture was cooled to 50°C, neutralized by adding 84 parts by mass of triethylamine, and then solubilized by adding 7,000 parts by mass of water. The resulting transparent reaction product was heated under reduced pressure at 40 to 60°C to remove methyl ethyl ketone, and then water was added to adjust the concentration, yielding a stable translucent colloidal aqueous dispersion with a nonvolatile content of 25%.

[0160] (Resin Particle Preparation Example 4) <Preparation of Water-Dispersible Polyurethane Resin (D)> 1,000 parts by mass of polyester polyol P-1 was dehydrated at 100°C under reduced pressure, then cooled to 80°C, and 907 parts by mass of methyl ethyl ketone was added, thoroughly stirred to dissolve, and 80 parts by mass of 2,2'-dimethylolpropionic acid was added. Next, 281 parts by mass of isophorone diisocyanate was added and reacted at 75°C for 8 hours to carry out urethane formation. After confirming that the isocyanate value was 0.1% by mass or less, the mixture was cooled to 50°C, neutralized by adding 60 parts by mass of triethylamine, and then solubilized by adding 7,000 parts by mass of water. The resulting transparent reaction product was heated under reduced pressure at 40°C to 60°C to remove methyl ethyl ketone, and then water was added to adjust the concentration, resulting in a stable, translucent, colloidal aqueous dispersion with a nonvolatile content of 25% by mass.

[0161] (Resin Particle Preparation Example 5) <Preparation of Acrylic-Silicone Polymer Microparticles A> After thoroughly replacing the air in a 1 L flask equipped with a mechanical stirrer, thermometer, nitrogen gas inlet tube, reflux condenser, and dropping funnel with nitrogen gas, 350 g of ion-exchanged water was mixed with 8.0 g of Latemul S-180 (Kao Corporation, reactive anionic surfactant), and the mixture was heated to 65°C. Next, 3.0 g of reaction initiator t-butyl peroxobenzoate and 1.0 g of sodium isoascorbate were added, and after 5 minutes, a mixture of 45 g of methyl methacrylate, 160 g of 2-ethylhexyl methacrylate, 5 g of acrylic acid, 45 g of butyl methacrylate, 30 g of cyclohexyl methacrylate, 15 g of vinyltriethoxysilane, 8.0 g of Latemul S-180, and 340 g of ion-exchanged water was added dropwise over 3 hours. Next, the mixture was heated and aged at 80°C for 2 hours, then cooled to room temperature, and the pH was adjusted to 7 to 8 with sodium hydroxide. Next, the ethanol was removed by distillation using an evaporator, and the moisture content was adjusted to obtain 730 g of acrylic-silicone polymer microparticles with a solid content of 40% by mass. 50 When measured using a particle size distribution analyzer (Nanotrac UPA-EX150, manufactured by Nikkiso Co., Ltd.), the particle size was 125 nm.

[0162] Example 1 <Ink preparation> A container equipped with a stirrer was charged with 65.00 parts by mass of 3-methoxy-N,N-dimethylpropanamide, 2.00 parts by mass of 2-ethyl-1,3-hexanediol, 5.00 parts by mass of propylene glycol, 0.40 parts by mass of 2,5,8,11-tetramethyldecane-5,8-diol, 1.00 part by mass of the polyether-modified siloxane compound represented by the above formula (8), and 1.00 part by mass of the photoacid generator represented by the above structural formula (1), and the mixture was mixed and stirred for 30 minutes. Next, 0.10 parts by mass of Unidyne DSN403N (polyoxyethylene perfluoroalkyl ether, manufactured by Daikin Industries, Ltd., active ingredient 100%), 0.05 parts by mass of antiseptic and antifungal agent (manufactured by Avecia, Proxel GXL), 0.30 parts by mass of 2-amino-2-ethyl-1,3-propanediol, 20.00 parts by mass of the carbon black pigment-containing polymer microparticle dispersion of Preparation Example 8, and pure water in an amount to make the total 100% by mass were added and mixed and stirred for 60 minutes. The resulting mixture was then pressure filtered through a polyvinylidene fluoride membrane filter with an average pore size of 1.2 μm to remove coarse particles and dust, thereby obtaining the ink of Example 1.

[0163] Example 2 <Ink preparation> A container equipped with a stirrer was charged with 7.50 parts by mass of 3-methoxy-N,N-dimethylpropanamide, 5.00 parts by mass of propylene glycol monopropyl ether, 22.00 parts by mass of propylene glycol, 2.00 parts by mass of 2-ethyl-1,3-hexanediol, 0.50 parts by mass of 2,4,7,9-tetramethyldecane-4,7-diol, 1.50 parts by mass of the polyether-modified siloxane compound represented by the above formula (8), and 1.50 parts by mass of the photoacid generator represented by the above structural formula (2), and the mixture was mixed and stirred for 30 minutes. Next, 0.05 parts by mass of an antiseptic and antifungal agent (Proxel GXL manufactured by Avecia), 0.30 parts by mass of 2-amino-2-ethyl-1,3-propanediol, 24.00 parts by mass of water-dispersible polyurethane resin (A), 1.62 parts by mass of polyurethane dispersion (Takelac W-6110 manufactured by Mitsui Chemicals, Inc.), 15.00 parts by mass of the surface-modified black pigment dispersion of Preparation Example 1, and pure water in an amount to make the total 100% by mass were added and mixed and stirred for 60 minutes. The resulting mixture was then pressure filtered through a polyvinylidene fluoride membrane filter with an average pore size of 1.2 μm to remove coarse particles and dust, thereby obtaining the ink of Example 2.

[0164] (Examples 3 to 22 and Comparative Examples 1 to 5) <Ink preparation> In the same manner as in Examples 1 and 2, the organic solvent, surfactant, foam inhibitor (antifoaming agent), and photoacid generator shown in each column of Examples 3 to 22 and Comparative Examples 1 to 5 in Tables 1 to 4 were mixed and stirred, followed by mixing and stirring of the antifungal agent, pH adjuster, and colorant (pigment dispersion), and then mixing and stirring of the water-dispersible polyurethane resin and resin particles. The resulting mixture was pressure-filtered through a polyvinylidene fluoride membrane filter with an average pore size of 1.2 μm to remove coarse particles and dust, yielding the inks of Examples 3 to 22 and Comparative Examples 1 to 5.

[0165] [Table 1]

[0166] [Table 2]

[0167] [Table 3]

[0168] [Table 4]

[0169] The details of the components and abbreviations in Tables 1 to 4 are as follows: -resin- Superflex 300: Polyurethane dispersion, solid content 30.0% by mass, glass transition temperature (Tg) = -42°C, manufactured by Daiichi Kogyo Seiyaku Co., Ltd. Takelac W-6110: Polyurethane dispersion, solid content 30.9% by mass, glass transition temperature (Tg) = -20°C, manufactured by Mitsui Chemicals, Inc.

[0170] -Surfactants- TEGO Wet270: Polyether-modified siloxane compound, manufactured by Evonik, 100% active ingredient Silface SAG503A: Polyether-modified siloxane compound, manufactured by Nissin Chemical Industry Co., Ltd., 100% active ingredient Surfynol 104E, manufactured by Nissin Chemical Industry Co., Ltd., active ingredient 50% Surfynol 420, manufactured by Nissin Chemical Industry Co., Ltd., 100% active ingredient Olfin EXP.4300, manufactured by Nissin Chemical Industry Co., Ltd., active ingredient 60% Unidyne DSN403N: Polyoxyethylene perfluoroalkyl ether, manufactured by Daikin Industries, Ltd., 100% active ingredient Proxel GXL: Antiseptic and antifungal agent with 1,2-benzisothiazolin-3-one as the main ingredient (manufactured by Avecia, contains 20% dipropylene glycol)

[0171] Next, the physical properties of each of the resulting inks of Examples 1 to 22 and Comparative Examples 1 to 5 were measured as follows. The results are shown in Table 5.

[0172] <Ink viscosity> The viscosity of the ink was measured at 25°C using a viscometer (RE-85L, manufactured by Toki Sangyo Co., Ltd.).

[0173] <Ink pH> The pH of the ink was measured at 25°C using a pH meter (HM-30R model, manufactured by TOA-DKK Corporation).

[0174] <Static surface tension of ink> The static surface tension of the ink was measured at 25°C using an automatic surface tensiometer (DY-300, manufactured by Kyowa Interface Science Co., Ltd.).

[0175] <Dynamic surface tension of ink> The dynamic surface tension of the ink when the surface life was 15 msec was measured at 25°C using a SITA DynoTester (manufactured by SITA) by the maximum bubble pressure method.

[0176] [Table 5]

[0177] Next, the storage stability of each ink was evaluated as follows, and the results are shown in Table 6.

[0178] <Ink storage stability> For each ink, a viscometer (RE-85L, manufactured by Toki Sangyo Co., Ltd.) was used to measure the viscosity at 25°C before storage and the viscosity at 25°C after storage in a sealed container at 60°C for 7 days. The viscosity change rate was calculated using the following formula and evaluated based on the following evaluation criteria.

[0179]

number

[0180] -Image formation- Under environmental conditions adjusted to 23°C ± 0.5°C and 50% ± 5% RH, an inkjet printing device [RICOH Pro L4160, a modified model equipped with a UV light irradiation (metal halide lamp) device manufactured by Ricoh Co., Ltd.] was used, and the driving voltage of the piezo element was varied to ensure a uniform amount of ink was ejected, and the settings were made so that the same amount of ink was deposited on the recording medium. The inks prepared were filled into an inkjet printing device [RICOH Pro L4160, a modified Ricoh model equipped with a UV light irradiation (metal halide lamp) device], and a chart containing 64-point JIS X 0208 (1997) 2223 general symbols created using Microsoft Word 2000 (Microsoft) was converted to digital data using Photoshop (registered trademark) without color correction and printed at 600 dpi x 600 dpi. Simultaneously with printing, the device was irradiated with UV light (integrated light intensity of 1450 mJ / cm from 320 nm to 390 nm). 2 ) and then dried in a dryer at 70°C for 2 minutes. JIS X 0208 (1997), 2223 is a symbol whose outer shape is a square and whose entire surface is filled with ink.

[0181] Next, the image density, beading, and fixability (abrasion resistance) of each of the obtained images were evaluated as follows. The results are shown in Table 6.

[0182] <Image density> The image density of the solid portion of each image obtained was measured using a spectrophotometer (X-rite exact, manufactured by X-rite Corporation) and evaluated according to the following criteria, with B or higher being a practically usable level.

[0183] [Evaluation criteria] A: Black: 2.5 or higher Yellow: 1.2 or higher Magenta: 1.9 or higher Cyan: 2.3 or higher B: Black: 2.2 or more, less than 2.5 Yellow: 1.1 or more, less than 1.2 Magenta: 1.75 or more, less than 1.9 Cyan: 2.1 or more, less than 2.3 C: Black: 2.0 or more, less than 2.2 Yellow: 1.0 or more, less than 1.1 Magenta: 1.6 or more, less than 1.75 Cyan: 1.9 or more, less than 2.1 D: Black: Less than 2.0 Yellow: Less than 1.0 Magenta: Less than 1.6 Cyan: Less than 1.9

[0184] <Beading> Each ink was printed as a solid image on PVC media under the same printing conditions as the image density. Beading (uneven density) in the solid image area was observed and evaluated according to the following evaluation criteria. A grade of B or higher is considered to be practically usable. [Evaluation criteria] A: No uneven density at all B: Slight unevenness in density C: Uneven density D: Severe unevenness in density

[0185] <Fixability (scratch resistance)> Each ink was printed as a solid image on PVC media under the same printing conditions as the image density above. The solid image area was rubbed with dry cotton (Kanakin No. 3) under a weight of 400 g, and the rub resistance was evaluated according to the following criteria. A grade of B or higher is considered practically usable. [Evaluation criteria] A: The image remains unchanged even after rubbing it over 100 times. B: After 100 rubs, some scratches remain but do not affect image density. C: Image density decreases after rubbing 100 times D: Image density decreases after rubbing 50 times or less

[0186] [Table 6]

[0187] (Examples 23 to 35 and Comparative Examples 6 to 7) Color bleeding was evaluated as follows using each ink set shown in Table 7. The results are shown in Table 7.

[0188] <Color Bleed> A solid image was printed on PVC media using each ink set under the same printing conditions as the image density described above. To evaluate color bleed, a solid image was simultaneously printed adjacent to the ink being evaluated using an ink of a different color. For example, if the evaluation ink was black, yellow ink was printed adjacent to the image, and if the evaluation ink was cyan, magenta ink was printed adjacent to the image. The degree of color bleed (bleeding across the color boundary) was visually observed and evaluated according to the following criteria. [Evaluation criteria] A: No color boundary bleeding at all B: Slight color boundary bleeding C: There is bleeding at the color boundary. D: Severe color boundary bleeding

[0189] [Table 7]

[0190] The present invention includes, for example, the following aspects. <1> an anionic compound, an organic solvent, water, and a photoacid generator; Only surfactants, polyurethane resin particles, anti-mold agents, foam inhibitors, and pH adjusters Contains The organic solvent has a solubility parameter of 9 ( cal / cm 3 ) 1 / 2 Over 11.8( cal / cm 3 ) 1 / 2 Contains at least one of the following organic solvents: and, Does not contain cationic polymerizable monomers The ink is characterized by: <2> Solubility parameter 9( cal / cm 3 ) 1 / 2 Over 11.8( cal / cm 3 ) 1 / 2 The content of the organic solvent is 5% by mass or more and 60% by mass or less. <1> The ink is as described in <3> The photoacid generator is either a compound represented by the following general formula (I) or a compound represented by the following general formula (II): <1> from <2> The ink is any one of the above. [ka] In the general formula (I), R1, R2, and R3 each represent a hydrogen atom, a lower alkyl group having 1 to 4 carbon atoms, an alkoxy group, or a thiophenyl group. m represents 0 or an integer of 1 to 3. Counter ion X - is F3CSO 3- , F9C4SO3 - , CH3C6H4SO3 - , PF6 - , SbF6 - , (Rf) n PF 6-n - , 10-camphor SO 3- , or B(C6F5)4 - (wherein Rf is a fluorocarbon alkyl group, and n is an integer of 1 to 5). [ka] In the general formula (II), R4 represents a hydrogen atom or a lower alkyl group having 1 to 4 carbon atoms. R5 represents a hydrogen atom, a lower alkyl group having 1 to 4 carbon atoms, a phenyl group, a substituted phenyl group, or a naphthalene group. R6 represents a hydrogen atom, a lower alkyl group having 1 to 4 carbon atoms, an acetyl group, or a methoxycarbonyl group. Counter ion X 1- PF6 - , SbF6 - , or B(C6F5)4- Shows. <4> The content of the photoacid generator is 0.25% by mass or more and 5% by mass or less. <1> from <3> The ink is any one of the above. <5> The anionic compound is at least one of an anionic resin and an anionic pigment. <1> from <4> The ink is any one of the above. <6> The above-mentioned further contains a surfactant. <1> from <5> The ink is any one of the above. <7> The surfactant is at least one of a polyether-modified siloxane compound, an acetylene glycol surfactant, and an acetylene alcohol surfactant. <6> The ink is as described in <8> An ink set having at least two inks selected from a cyan ink, a magenta ink, a yellow ink, and a black ink, The inks constituting the ink set are <1> from <7> 1. An ink set comprising the ink according to any one of the preceding items. <9> The aforementioned <1> from <7> 1. An ink container characterized in that the ink according to any one of the above items is contained in a container that has been treated to block ultraviolet light. <10> On the substrate <1> from <7> an application step of applying the ink according to any one of the above items; and an ultraviolet light irradiation step of irradiating the applied ink with ultraviolet light. <11> On the substrate <1> from <7> an ink applying means for applying the ink according to any one of the above items; and ultraviolet light irradiating means for irradiating the ink with ultraviolet light after application.

[0191] The aforementioned <1> from <7> The ink according to any one of <8> The ink set according to <9> The ink container according to <10> and the printing method described in <11> According to the printing apparatus described in the above, the conventional problems can be solved and the object of the present invention can be achieved. [Explanation of symbols]

[0192] 1. Inkjet recording device 2 Head carriage 3 Inkjet recording head 4 Ultraviolet irradiation means 5 Platen and heater section 6 Ink ejection section S Recording Media [Prior art documents] [Patent documents]

[0193] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-140993 [Patent Document 2] Japanese Patent Application Laid-Open No. 2016-216701

Claims

1. The composition contains only an anionic compound, an organic solvent, water, a photoacid generator, a surfactant, polyurethane resin particles, a mildew inhibitor, a foam inhibitor, and a pH adjuster. The organic solvent has a solubility parameter of 9 (cal / cm ３ ) １／２ 11.8 (cal / cm) ３ ) １／２ At least one of the following organic solvents is included: An ink characterized by not containing a cationically polymerizable monomer.

2. Solubility parameter 9 (cal / cm ３ ) １／２ 11.8 (cal / cm) ３ ) １／２ The ink according to claim 1 , wherein the content of the organic solvent is 5% by mass or more and 60% by mass or less.

3. 3. The ink according to claim 1, wherein the photoacid generator is either a compound represented by the following general formula (I) or a compound represented by the following general formula (II): 【Chemical 1】 However, in the general formula (I), R １ , R ２ , and R ３ represents a hydrogen atom, a lower alkyl group having 1 to 4 carbon atoms, an alkoxy group, or a thiophenyl group. m represents 0 or an integer of 1 to 3. Counter ion X － is F3CSO ３－ , F ９ C4SO ３ － , C.H. ３ C ６ H ４ SO ３ － , P.F. ６ － , SbF ６ － , (Rf) ｎ PF ６－ｎ － , 10-camphor SO ３－ , or B(C ６ F ５ ) ４ － (wherein Rf is a fluorocarbon alkyl group, and n is an integer of 1 to 5). 【Chemistry 2】 However, in the general formula (II), R ４ represents a hydrogen atom or a lower alkyl group having 1 to 4 carbon atoms. ５ represents a hydrogen atom, a lower alkyl group having 1 to 4 carbon atoms, a phenyl group, a substituted phenyl group, or a naphthalene group. ６ represents a hydrogen atom, a lower alkyl group having 1 to 4 carbon atoms, an acetyl group, or a methoxycarbonyl group. １－ is PF ６ － , SbF ６ － , or B(C ６ F ５ ) ４ － Shows.

4. The ink according to claim 1 , wherein the content of the photoacid generator is 0.25% by mass or more and 5% by mass or less.

5. The ink according to claim 1 , wherein the anionic compound is at least one of an anionic resin and an anionic pigment.

6. The ink according to claim 1 , further comprising a surfactant.

7. The ink according to claim 6, wherein the surfactant is at least one of a polyether-modified siloxane compound, an acetylene glycol surfactant, and an acetylene alcohol surfactant.

8. An ink set having at least two inks selected from a cyan ink, a magenta ink, a yellow ink, and a black ink, 8. An ink set, wherein the inks constituting the ink set are the inks according to any one of claims 1 to 7.

9. 8. An ink container comprising the ink according to claim 1 housed in a container that has been treated to block ultraviolet light.

10. an application step of applying the ink according to any one of claims 1 to 7 onto a substrate; an ultraviolet light irradiation step of irradiating the applied ink with ultraviolet light.

11. an application means for applying the ink according to any one of claims 1 to 7 onto a substrate; and ultraviolet light irradiating means for irradiating the ink with ultraviolet light after application.

Images