JP6613745B2 - Ink, image forming method, image forming apparatus and image formed product - Google Patents

Description

  The present invention relates to an ink, an image forming method using the ink, an image forming apparatus, and an image formed product.

  Inkjet recording methods have been rapidly spreading in recent years because they can easily record color images and have low running costs. As the ink for ink jet recording, an aqueous dye ink in which a dye is dissolved in an aqueous medium, or a solvent-based ink in which an oil-soluble dye is dissolved in an organic solvent is used. In general, from the viewpoint of environment and safety, in offices and homes, water-soluble dyes dissolved in water or water and water-soluble organic solvents are used. However, it is a problem that a recorded image formed with an ink containing such a water-soluble dye is inferior in water resistance and light resistance.

  On the other hand, an aqueous pigment ink in which a pigment is dispersed in water in the form of fine particles has attracted attention. Ink jet recording inks using water-dispersible pigments are known to be excellent in water resistance and light resistance. However, when recording on glossy paper using pigment ink, the pigment as the color material does not penetrate into the ink receiving layer and remains on the surface of the glossy paper to form a coating film. For this reason, compared to recording with pigment ink on plain paper or recording with dye ink that penetrates into the ink receiving layer, the recording surface is inferior in abrasion resistance. There is a problem that the film peels off or the fouling material becomes dirty.

In order to add such a method of combining a resin-coated pigment and a polyurethane resin (Patent Document 1) and a function of reducing the friction coefficient of the printed image surface to such a problem of scratch resistance, Addition of wax as a slipping agent has been proposed (Patent Document 2). However, such inks with excellent abrasion resistance have a low reliability of discharge due to local drying at the nozzle part of the ink jet printer head, and maintainability due to thickening and coagulation during the evaporation of water in the waste ink. Decline is a problem.
Therefore, a method has been proposed in which the durability of the image film is improved by including an amine neutralized resin, and at the same time, the discharge stability is achieved by including glycol ethers or alkanediols (Patent Document 3).
Further, in order to achieve both post-printing drying properties and abrasion resistance, a method using a combination of a water-soluble organic amine salt organic resin and a dihydric alcohol solvent having no ether bond has also been proposed (Patent Document 4).

  When printing on glossy paper, the recorded material must have good abrasion resistance. The resin selected for the ink for ink jet recording having such good abrasion resistance has a large increase in viscosity when water evaporates, nozzle clogging due to drying of the ink and ejection failure due to adhesion around the nozzle of the ink, Furthermore, there is a problem that the maintainability is deteriorated due to thickening and coagulation of the waste ink.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide an ink that achieves both good abrasion resistance and good ejection stability and maintenance by suppressing the increase in viscosity during ink water evaporation.

  As a result of intensive studies on the above problems by the present inventors, by using urethane resin particles and a specific amine compound in combination, it is possible to suppress an increase in viscosity at the time of water evaporation while improving abrasion resistance. It has been found that it is possible to achieve both excellent abrasion resistance, good ejection reliability, and maintainability.

That is, the present invention
An ink containing a colorant, an organic solvent, resin particles, an amine compound and water, wherein the resin particles are an anionic urethane resin, and the amine compound has an organic compound having a boiling point of 120 ° C. or higher and 200 ° C. or lower and a molecular weight of 100 or lower. The present invention relates to an ink which is an amine compound, wherein the content of the amine compound is 0.01 or more and 1.00 or less when the content (mass basis) of the resin particles in the ink is 1.

  According to the present invention, it is possible to provide an ideal ink that is capable of recording excellent in abrasion resistance on glossy paper as well as plain paper, and that has excellent ejection stability from the head nozzle and good maintainability. Can do.

1 is an overall view of an image forming apparatus according to the present invention. It is an enlarged view of the pretreatment liquid coating apparatus in the present invention. 2 is a droplet discharge head according to the present invention. It is an enlarged view of a droplet discharge head in the present invention. It is a cross-sectional explanatory drawing along the liquid chamber longitudinal direction of the droplet discharge head. FIG. 6 is a cross-sectional explanatory diagram of a droplet discharge head liquid chamber in a lateral direction.

Hereinafter, the present invention will be described in more detail with reference to preferred embodiments.
In the present invention, by using an anionic urethane resin for the resin particles contained in the ink, it is possible to achieve both improvement in image abrasion resistance and good maintainability when recorded on glossy paper. This is because the polyurethane resin is excellent in adhesion to the substrate and has high wear resistance. Moreover, it is preferable to reduce the particle diameter of the resin particles. Thereby, it becomes possible to form a coating film so as to fill a gap between the pigment and the medium and between the pigment and the pigment, and higher abrasion resistance can be obtained. Furthermore, it is preferable to use a polycarbonate urethane resin or a polyester urethane resin from the viewpoint of ejection stability and storage stability.
Further, by containing an amine compound having a boiling point of 120 to 200 ° C. and a molecular weight of 100 or less in the ink, an increase in viscosity at the time of water evaporation is suppressed, and both high ejection stability and maintainability can be achieved. This is because by reducing the molecular weight of the amine compound, substitution occurs as a counter ion of the water-dispersible resin, and by adding an amine compound having a boiling point higher than that of water into the ink, the resin particles By preventing the counter ions from evaporating and maintaining a stable dispersion state, an increase in the viscosity of the ink is suppressed. In addition, when the content (mass basis) of the resin particles in the ink is 1, the content of the amine compound is 0.01 or more and 1.00 or less, thereby increasing the viscosity of the ink when water is evaporated by the amine compound. Storage stability can be ensured while exhibiting an inhibitory effect. This makes it possible to achieve both high abrasion resistance, ejection stability, and maintainability.
The static surface tension of the ink at 25 ° C. is preferably 20 mN / m or more and 27 mN / m or less. More preferably, a fluorine-based surfactant and an acetylene glycol-based surfactant as shown in the following formula (V) and / or a foam suppressor as shown in the formula (VII) are added. This is true. By adding these surfactants and antifoaming agents, it is possible to achieve both high density and antifoaming properties of plain paper.

Hereinafter, the ink and image forming method of the present invention, the image forming apparatus using the ink, and the image formed product using the ink will be described in detail.
<Ink>
-Resin particles-
By adding an anionic urethane resin as resin particles to the ink in the present invention, it is possible to achieve both improved gloss paper rubbing resistance and good maintainability.
The polyurethane resin is a reactive product of polyisocyanate and polyol. A characteristic of the polyurethane resin is that it exhibits the performance of a soft segment made of a polyol component having a weak cohesive force and a hard segment made of a urethane bond having a strong cohesive force. The soft segment is soft and resistant to deformation of the base material such as stretching and bending. On the other hand, the hard segment has high adhesion to the substrate and is excellent in wear resistance. Therefore, high gloss paper rubbing resistance can be expected by adding it to the ink.
The polyurethane resin particles are water dispersible, and are particularly preferably used as an O / W type water dispersion. Examples of such a dispersion include an aqueous dispersion obtained by emulsifying a polyurethane resin using an emulsifier, and a self-emulsification type aqueous dispersion obtained by introducing a functional group having the function of an emulsifier by copolymerization or the like.
Among these, a self-emulsifying anionic polycarbonate-based or polyester-based polyurethane resin aqueous dispersion is preferable because of excellent dispersion stability. Further, from the viewpoint of dispersion stability and ink storage stability, a polycarbonate-based polyurethane resin aqueous dispersion is more preferable.
The particle diameter (D50) of the resin particles is related to the viscosity of the dispersion. If the composition is the same, the smaller the particle diameter, the higher the viscosity at the same solid content. In the present invention, from the viewpoint of image abrasion resistance when recorded on glossy paper, the particle diameter (D50) of the resin particles is preferably 10 nm or more and 100 nm or less, and more preferably 10 nm or more and 50 nm or less. By using resin particles having a particle diameter (D50) of 10 nm or more, thickening of the ink can be prevented and storage stability is also improved. Furthermore, it is preferable to use resin particles having a particle size (D50) of 100 nm or less, and high abrasion resistance that suppresses image elongation can be obtained. Further, it is more preferably 10 nm or more and 50 nm or less, and after rubbing, it is possible to form an image without image peeling.

The resin particles have a function of fixing the colorant to the paper surface, and are preferably formed into a film at room temperature to improve the fixability of the colorant. Therefore, the minimum film forming temperature (MFT) of the water dispersible resin is preferably 30 ° C. or lower. Further, when the glass transition temperature of the water-dispersible resin is -40 ° C. or lower, the resin film becomes more viscous and the printed matter is tacky. Therefore, the water-dispersible resin has a glass transition temperature of −30 ° C. or higher. It is preferable.
The content of the water-dispersible resin in the ink is desirably 1% by mass to 10% by mass, and more preferably 1.5% by mass to 5% by mass. When the content is 1% by mass or more, better abrasion resistance can be obtained, and when the content is 10% by mass or less, an increase in viscosity at the time of water evaporation is suppressed and good maintainability is maintained. Can do.

  Furthermore, in the present invention, when the content (mass basis) of the colorant in the ink is 1, the content of the resin particles is preferably 0.05 or more and 2 or less. Fixability can be ensured by being 0.05 or more with respect to the content (mass basis) 1 of the colorant, and good ejection stability can be secured by being 2 or less.

  In addition to the anionic polyurethane resin aqueous dispersion, other water-dispersible resins can be used as the water-dispersible resin contained in the ink of the present invention. Examples of other water-dispersible resins include acrylic resins, styrene acrylic resins, acrylic silicone resins, and fluorine resins.

-Amine compound-
In the present invention, the ink contains an amine compound having a boiling point of 120 ° C. or higher and 200 ° C. or lower, preferably a boiling point of 130 ° C. or higher and 180 ° C. or lower, and a molecular weight of 100 or lower, preferably a molecular weight of 90 or lower. When the (mass standard) is 1, the content of the amine compound is 0.01 or more and 1.00 or less, and preferably the content is 0.01 or more and 0.08 or less, thereby realizing good maintainability. doing.

  The amine compound may be any of primary, secondary, tertiary, quaternary amine and salts thereof. The quaternary amine means a compound in which four alkyl groups are substituted on the nitrogen atom.

  The amine compound is preferably a compound represented by the following formula (I) or formula (II).

［式中、Ｒ₁、Ｒ₂、Ｒ₃は水素原子、炭素数１〜４のアルコキシ基、炭素数１〜６のアルキル基、ヒドルキシエチル基を示す。但し、すべて水素原子である場合を除く。］

[Wherein R ₁ , R ₂ and R ₃ represent a hydrogen atom, an alkoxy group having 1 to 4 carbon atoms, an alkyl group having 1 to 6 carbon atoms, and a hydroxyethyl group. However, the case where all are hydrogen atoms is excluded. ]

［式中、Ｒ₄、Ｒ₅、Ｒ₆は水素原子、メチル基、エチル基、ヒドロキシメチル基、１〜４のアルキル基を示す。］

[Wherein R ₄ , R ₅ and R ₆ represent a hydrogen atom, a methyl group, an ethyl group, a hydroxymethyl group, or an alkyl group of 1 to 4; ]

Examples of the compounds represented by formula (I) and formula (II) include 1-amino-2-propanol, 3-amino-1-propanol, N-methylethanolamine, N, N-dimethylethanolamine, 1-amino- Examples include 2-methyl-propanol.
Although there is no restriction | limiting in particular in the content of the said amine compound in an ink, From a viewpoint of pH adjustment of an ink, 0.01 mass%-5 mass% are preferable, and 0.05 mass%-2 mass% are especially preferable. The amine compound contained in the ink can be used in combination with another amine compound in addition to the amine compound.

-Organic solvent-
In the ink of the present invention, a polyhydric alcohol having a solubility parameter (SP value) in the range of 11.8 to 14.0 is preferably used as the organic solvent. Examples of the polyhydric alcohol having the solubility parameter (SP value) in the range of 11.8 to 14.0 include the following compounds.
3-methyl-1,3-butanediol (SP value: 12.05), 1,2-butanediol (SP value: 12.75), 1,3-butanediol (SP value: 12.75), 1 , 4-butanediol (SP value: 12.95), 2,3-butanediol (SP value: 12.55), 1,2-propanediol (SP value: 13.48), 1,3-propanediol (SP value: 13.72), 1,2-hexanediol (SP value: 11.80), 1,6-hexanediol (SP value: 11.95), 3-methyl-1,5-pentanediol ( SP value: 11.80), triethylene glycol (SP value: 12.12), diethylene glycol (SP value: 13.02). Particularly preferably, 3-methyl-1,3-butanediol (SP value: 12.05), 1,2-butanediol (SP value: 12.75), 1,3-butanediol (SP value: 12.2. 75), 1,4-butanediol (SP value: 12.95), 2,3-butanediol (SP value: 12.55), 1,2-propanediol (SP value: 13.48), 1, 3-propanediol (SP value: 13.72) is preferred.

  In addition to the polyhydric alcohol, the remaining wetting agent can be used in combination with the ink of the present invention. The above polyhydric alcohol and the other wetting agent amount ratio (mass ratio) depend on the type and amount of other additives, and cannot be generally stated. For example, the range is, for example, 10/90 to 90/10. It is preferable that it is, and it is more preferable that it is 40/60-60/40. Examples of the wetting agent include polyhydric alcohols, polyhydric alcohol alkyl ethers, polyhydric alcohol aryl ethers, nitrogen-containing heterocyclic compounds, amides, amines, sulfur-containing compounds, propylene carbonate, ethylene carbonate, Other wetting agents can be mentioned.

Examples of the polyhydric alcohols include dipropylene glycol (bp 232 ° C.), 1,5-pentanediol (bp 242 ° C.), 3-methyl-1,3-butanediol (bp 203 ° C.), propylene glycol (bp 187 ° C.). 2-methyl-2,4-pentanediol (bp 197 ° C.), ethylene glycol (bp 196 to 198), 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 to 260 ° C.), 1,2,6-hexane triol (bp 178 ° C.), trimethylol ethane (solid, mp 199 to 201 ° C.), trimethylol propane (solid Mp 61 ° C.).
Examples of the polyhydric alcohol alkyl ethers include ethylene glycol monoethyl ether (bp 135 ° C.), ethylene glycol monobutyl ether (bp 171 ° C.), diethylene glycol monomethyl ether (bp 194 ° C.), diethylene glycol monobutyl ether (bp 231 ° C.), and ethylene glycol monoethyl ether. -2-ethylhexyl ether (bp 229 ° C.), propylene glycol monoethyl ether (bp 132 ° C.), and the like.
Examples of the polyhydric alcohol aryl ethers include ethylene glycol monophenyl ether (bp 237 ° C.) and ethylene glycol monobenzyl ether.
Examples of the nitrogen-containing heterocyclic compound include N-methyl-2-pyrrolidone (bp 202 ° C.), 1,3-dimethyl-2-imidazolidinone (bp 226 ° C.), ε-caprolactam (bp 270 ° C.), γ-butyrolactone. (Bp 204-205 ° C.).

Examples of the amides include formamide (bp 210 ° C.), N-methylformamide (bp 199 to 201), N, N-dimethylformamide (bp 153 ° C.), N, N-diethylformamide (bp 176 to 177 ° C.) and the like. It is done.
Examples of the amines include monoethanolamine (bp 170 ° C), diethanolamine (bp268 ° C), triethanolamine (bp360 ° C), N, N-dimethylmonoethanolamine (139 ° C), N-methyldiethanolamine (bp243 ° C). ), N-methylethanolamine (bp 159 ° C.), N-phenylethanolamine (bp 282 to 287), 3-aminopropyldiethylamine (bp 169 ° C.) and the like.
Examples of the sulfur-containing compounds include dimethyl sulfoxide (bp 139 ° C.), sulfolane (bp 285 ° C.), thiodiglycol (bp 282 ° C.), and the like.
The total content of the polyhydric alcohol having a solubility parameter (SP value) in the ink of 11.8 to 14.0 and the organic solvent of the wetting agent is 30 to 50% by mass of the whole ink. Is preferred.
When the content is less than 30% by mass, the viscosity at the time of water evaporation increases remarkably, and when it exceeds 50% by mass, the drying property may become severe.

-Penetration agent-
The penetrant used by mixing with the organic solvent preferably contains at least one non-wetting agent polyol compound or glycol ether compound having 8 to 11 carbon atoms.
Here, the non-wetting agent property means having a solubility of between 0.2 and 5.0% by mass in water at 25 ° C. Among these penetrants, 1,3-diol compounds represented by the general formula (III) are preferable, and 2-ethyl-1,3-hexanediol [solubility: 4.2% (25 ° C.)], 2, 2,4-trimethyl-1,3-pentanediol [solubility: 2.0% (25 ° C.)] is particularly preferred.

［式中、Ｒ₇はメチル基又はエチル基であり、Ｒ₈は水素又はメチル基であり、Ｒ₉はエチル基又はプロピル基である。］

[Wherein R ₇ is a methyl group or an ethyl group, R ₈ is hydrogen or a methyl group, and R ₉ is an ethyl group or a propyl group. ]

Examples of other non-wetting agent polyol compounds include aliphatic diols such as 2-ethyl-2-methyl-1,3-propanediol, 3,3-dimethyl-1,2-butanediol, 2,2- Diethyl-1,3-propanediol, 2-methyl-2-propyl-1,3-propanediol, 2,4-dimethyl-2,4-pentanediol, 2,5-dimethyl-2,5-hexanediol, 5-hexene-1,2-diol and the like.
The amount of penetrant contained in the entire ink is preferably in the range of 0.5 to 5 mass%, more preferably in the range of 1 to 3 mass%. When the content is less than 0.5% by mass, the ink permeability effect cannot be obtained, and the image quality cannot be obtained. If it exceeds 5% by mass, problems such as separation without dissolving in the ink and an increase in the initial ink viscosity may occur.

-Colorant-
Next, the colorant used in the present invention will be described.
As the colorant, a pigment is mainly used from the viewpoint of weather resistance, but a dye may be contained within a range that does not deteriorate the weather resistance for the purpose of adjusting the color tone. The content of the colorant is preferably 2 to 15% by mass, more preferably 3 to 12% by mass based on the total ink in terms of solid content. If the content is less than 2% by mass, the color developability and the image density of the ink may be lowered. Absent. There is no restriction | limiting in particular as a pigment, According to the objective, it can select suitably, For example, the inorganic pigment and organic pigment for black or color are mentioned.
As the particularly preferred water-dispersible colorant when the colorant is a pigment, the following first and second forms can be mentioned.
(1) First form: The colorant contains an aqueous dispersion of polymer fine particles containing a pigment that is insoluble or hardly soluble in water.
(2) Second form: The colorant has at least one hydrophilic group on the surface and exhibits water dispersibility in the absence of a dispersant (hereinafter sometimes referred to as “self-dispersible pigment”). ).
As the water-dispersible colorant of the first form, it is preferable to use a polymer emulsion in which a pigment is contained in polymer fine particles in addition to the pigment.
The polymer emulsion in which the pigment is contained in the polymer fine particles is one in which the pigment is encapsulated in the polymer fine particles, or the pigment is adsorbed on the surface of the polymer fine particles.
In the present invention, it is preferable to use a self-dispersing pigment or a resin-coated pigment as the water-dispersible colorant. By using a self-dispersing pigment, higher fluidity during water evaporation can be obtained, and by using a resin-coated pigment, higher glossy paper fixability can be obtained.
The resin-coated colorant can be stably dispersed without using a dispersant by coating a pigment with a resin having a hydrophilic group and microencapsulating it.
The content of the pigment derived from the colorant in the ink is preferably 3.0% by mass or more and 10.0% by mass or less. When the pigment content is less than 3.0% by mass, the image density may decrease, and when it exceeds 10% by mass, the ejection stability may decrease.

  Examples of the resin for coating the pigment include polyamide, polyurethane, polyester, polyurea, epoxy resin, polycarbonate, urea resin, melamine resin, phenol resin, polysaccharide, gelatin, gum arabic, dextran, casein, protein, natural rubber, carboxy Polymethylene, polyvinyl alcohol, polyvinyl pyrrolidone, polyvinyl acetate, polyvinyl chloride, polyvinylidene chloride, cellulose, ethyl cellulose, methyl cellulose, nitrocellulose, hydroxyethyl cellulose, cellulose acetate, polyethylene, polystyrene, (meth) acrylic acid polymer or co Polymer, (meth) acrylic acid ester polymer or copolymer, (meth) acrylic acid- (meth) acrylic acid ester copolymer, styrene- (meth) acrylic acid Le acid copolymer, styrene - maleic acid copolymer, sodium alginate, fatty acids, paraffin, beeswax, water wax, hardened beef tallow, carnauba wax, and albumin.

  Among these, it is preferable to use an organic polymer material having an anionic group such as a carboxylic acid group or a sulfonic acid group. Nonionic organic polymer materials include, for example, polyvinyl alcohol, polyethylene glycol monomethacrylate, polypropylene glycol monomethacrylate, methoxypolyethylene glycol monomethacrylate or their (co) polymers, and 2-oxazoline cationic ring-opening polymers. Etc. In particular, a completely saponified product of polyvinyl alcohol is particularly preferable because it has low water solubility and is easily dissolved in hot water but difficult to dissolve in cold water.

  The content of the organic polymer material constituting the wall film substance of the microcapsule of the resin-coated colorant is preferably 15% by mass or more and 40% by mass or less. By making the amount of the organic polymer material within the above range, the content of the organic polymer material in the capsule is relatively low, so that the color development of the pigment caused by the organic polymer material covering the pigment surface Can be suppressed. When the amount of the organic polymer material is less than 15% by mass, it is difficult to exert the effect of encapsulation. Conversely, when the amount exceeds 40% by mass, the color developability of the pigment is significantly reduced.

  As the pigment, carbon black or a color pigment is used.

As the carbon black, carbon black produced by a furnace method or a channel method has a primary particle size of 15 to 40 millimicrons, a specific surface area by the BET method of 50 to 300 m ² / g, and a DBP oil absorption of 40 Those having ˜150 ml / 100 g, volatile content of 0.5-10% and pH value of 2-9 are preferred. Examples of such carbon black include No. 2300, no. 900, MCF-88, no. 33, no. 40, no. 45, no. 52, MA7, MA8, MA100, no. 2200B (Mitsubishi Chemical Co., Ltd.), Raven700, 5750, 5250, 5000, 3500, 1255 (Made in Colombia), Regal400R, 330R, 660R, MululL, Monarch700, 800, 880, 900, 1000, 1100, 1300, Monarch1400 (Above, manufactured by Cabot), Color Black FW1, FW2, FW2V, FW18, FW200, S150, S160, S170, Printex 35, U, V, 140U, 140V, Special Black 6, 5, 4A, 4 (above, Degussa However, it is not limited to these.
Examples of the color pigment include anthraquinone, phthalocyanine blue, phthalocyanine green, diazo, monoazo, pyranthrone, perylene, heterocyclic yellow, quinacridone, and (thio) indigoid. Representative examples of phthalocyanine blue include copper phthalocyanine blue and its derivatives (Pigment Blue 15). Representative examples of quinacridone include Pigment Orange 48, Pigment Orange 49, Pigment Red 122, Pigment Red 192, Pigment Red 202, Pigment Red 206, Pigment Red 207, Pigment Red 209, Pigment Violet 19 and Pigment Violet 42. Representative examples of anthraquinones include pigment red 43, pigment red 194 (perinone red), pigment red 216 (brominated pyrantrone red) and pigment red 226 (pyrantron red). Representative examples of pyrerin are Pigment Red 123 (Bell Million), Pigment Red 149 (Scarlet), Pigment Red 179 (Maroon), Pigment Red 190 (Red), Pigment Violet, Pigment Red 189 (Yellow Shade Red) and Pigment Red. 224. Representative examples of thioindigoid include Pigment Red 86, Pigment Red 87, Pigment Red 88, Pigment Red 181, Pigment Red 198, Pigment Violet 36 and Pigment Violet 38. Representative examples of heterocyclic yellow include pigment yellow 117 and pigment yellow 138. Examples of other suitable colored pigments are described in The Color Index, Third Edition (The Society of Dyer's and Colorists, 1982).
Furthermore, if an organic pigment or self-dispersing carbon black, which is a self-dispersing pigment, is used as a colorant, the dispersibility of the pigment is improved even if the content of organic polymers in the capsule is relatively low. In addition, since sufficient storage stability of the ink can be secured, it is more preferable for the present invention.

  There is no restriction | limiting in particular in the average particle diameter of the said pigment, According to the objective, it can select suitably, 10 nm-150 nm are preferable, 20 nm-100 nm are more preferable, 30 nm-80 nm are still more preferable. When the average particle diameter exceeds 150 nm, not only the saturation of the printed image is lowered, but also thickening aggregation during ink storage and clogging of the nozzle during printing are likely to occur. On the other hand, when the average particle size of the pigment is less than 10 nm, not only the light resistance is lowered but also the storage stability tends to be deteriorated.

The average particle diameter of the pigment is, for example, a micro-track UPA-150 manufactured by Nikkiso Co., Ltd., and a sample diluted with pure water so that the pigment concentration (mass concentration) in the measurement sample is 0.01% by mass. , Particle refractive index 1.51, particle density 1.4 g / cm ³ , solvent parameter means 50% average particle diameter (D50) measured at 23 ° C. using pure water parameters.

  Although it is preferable to use a pigment as the resin-coated colorant used in the present invention, a dye may be used as the resin-coated colorant, and an example of this water-soluble dye is shown below. Those having excellent water resistance and light resistance are preferably used. Specific examples of these dyes include acid dyes and food dyes such as C.I. I. Acid Yellow 17, 23, 42, 44, 79, 142; C.I. I. Acid Red 1, 8, 13, 14, 18, 26, 27, 35, 37, 42, 52, 82, 87, 89, 92, 97, 106, 111, 114, 115, 134, 186, 249, 254 289; I. Acid Blue 9, 29, 45, 92, 249; I. Acid Black 1, 2, 7, 24, 26, 94; I. Food Yellow 3, 4; I. Food red 7, 9, 14; I. Food black 1, 2 etc. are mentioned.

  Examples of direct dyes include C.I. I. Direct yellow 1, 12, 24, 26, 33, 44, 50, 86, 120, 132, 142, 144; I. Direct Red 1, 4, 9, 13, 17, 20, 28, 31, 39, 80, 81, 83, 89, 225, 227; I. Direct orange 26, 29, 62, 102; I. Direct Blue 1, 2, 6, 15, 22, 25, 71, 76, 79, 86, 87, 90, 98, 163, 165, 199, 202; I. Direct black 19, 22, 32, 38, 51, 56, 71, 74, 75, 77, 154, 168, 171 and the like can be mentioned.

  Examples of basic dyes include C.I. I. Basic yellow 1, 2, 11, 13, 14, 15, 19, 21, 23, 24, 25, 28, 29, 32, 36, 40, 41, 45, 49, 51, 53, 63, 64, 65, 67, 70, 73, 77, 87, 91; C.I. I. Basic Red 2, 12, 13, 14, 15, 18, 22, 23, 24, 27, 29, 35, 36, 38, 39, 46, 49, 51, 52, 54, 59, 68, 69, 70, 73, 78, 82, 102, 104, 109, 112; I. Basic blue 1, 3, 5, 7, 9, 21, 22, 26, 35, 41, 45, 47, 54, 62, 65, 66, 67, 69, 75, 77, 78, 89, 92, 93, 105, 117, 120, 122, 124, 129, 137, 141, 147, 155; I. Basic black 2, 8 etc. are mentioned.

  Examples of reactive dyes include C.I. I. Reactive black 3, 4, 7, 11, 12, 17; I. Reactive Yellow 1, 5, 11, 13, 14, 20, 21, 22, 25, 40, 47, 51, 55, 65, 67; I. Reactive Red 1, 14, 17, 25, 26, 32, 37, 44, 46, 55, 60, 66, 74, 79, 96, 97; I. Reactive blue 1, 2, 7, 14, 15, 23, 32, 35, 38, 41, 63, 80, 95 etc. are mentioned.

  As a method for microencapsulating a water-insoluble pigment with an organic polymer material, all conventionally known methods can be used, including a chemical production method, a physical production method, a physicochemical method, a mechanical method. Examples include interfacial polymerization method, in-situ polymerization method, submerged cured coating method, coacervation (phase separation) method, submerged drying method, melt dispersion cooling method, air suspension. Examples thereof include a coating method, a spray drying method, an acid precipitation method, and a phase inversion emulsification method.

  Here, the microencapsulation will be briefly described. The interfacial polymerization method is a method in which two types of monomers or two types of reactants are separately dissolved in a dispersed phase and a continuous phase, and both substances are reacted at the interface between the two to form a wall film. The in-situ polymerization method is a method in which a liquid or gaseous monomer and catalyst, or two reactive substances are supplied from either one of the continuous phase core particles to cause a reaction to form a wall film, The submerged cured coating method is a method in which a droplet of a polymer solution containing core substance particles is insolubilized in a liquid with a curing agent or the like to form a wall film, and the coacervation (phase separation) method is This is a method in which a polymer dispersion in which core material particles are dispersed is separated into a coacervate (concentrated phase) and a dilute phase having a high polymer concentration, and a wall film is formed. Prepare a solution dispersed in the wall membrane material solution, The dispersion is put into a liquid in which the continuous phase of the dispersion is not miscible to form a composite emulsion, and the wall film is formed by gradually removing the medium in which the wall film material is dissolved. The method uses a wall film material that melts into a liquid state and solidifies at room temperature when heated, and this material is heated and liquefied. Core material particles are dispersed in it, cooled into fine particles, and formed into a wall film. In the air suspension coating method, powder core material particles are suspended in the air by a fluidized bed and suspended in the air stream, and the coating solution of the wall membrane material is sprayed and mixed to form a wall. The spray drying method is a method in which an encapsulated stock solution is sprayed and contacted with hot air to evaporate and dry volatile components to form a wall membrane. The acid precipitation method is an anion deposition method. Organic polymer compounds containing functional groups After neutralizing at least a part of the anionic group with a basic compound to give solubility in water and kneading in an aqueous medium together with a colorant, it is neutralized with an acidic compound or acidified to precipitate organic compounds. The phase inversion emulsification method is a method in which a mixture containing an anionic organic polymer having dispersibility in water and a colorant is mixed with an organic solvent. In this method, water is introduced into the organic solvent phase or the organic solvent phase is introduced into water.

  It is preferable to select an organic polymer suitable for the microencapsulation method. For example, in the case of interfacial polymerization, polyester, polyamide, polyurethane, polyvinyl pyrrolidone, epoxy resin and the like are suitable. In the case of using the in-situ polymerization method, a polymer or copolymer of (meth) acrylic acid ester, (meth) acrylic acid- (meth) acrylic acid ester copolymer, styrene- (meth) acrylic acid copolymer, Polyvinyl chloride, polyvinylidene chloride, polyamide and the like are suitable. In the case of the liquid curing method, sodium alginate, polyvinyl alcohol, gelatin, albumin, epoxy resin and the like are suitable. In the case of the coacervation method, gelatin, celluloses, casein and the like are suitable. In addition, in order to obtain a fine and uniform microencapsulated pigment, it is possible to use all conventionally known encapsulation methods other than those described above.

When the phase inversion method or the acid precipitation method is selected as the microencapsulation method, anionic organic polymers are used as the organic polymers constituting the wall membrane material of the microcapsules.
The phase inversion method is a combination of an anionic organic polymer having self-dispersibility or solubility in water and a composite or composite of carbon black, or carbon black, a curing agent, and an anionic organic polymer. In this method, the mixture is used as an organic solvent phase, and water is added to the organic solvent phase, or the organic solvent phase is added to water and microencapsulated while self-dispersing (phase inversion emulsification). Here, the carbon black includes self-dispersing carbon black. In the above phase inversion method, there is no problem even if the organic solvent phase is mixed with a recording liquid vehicle or additives. In particular, it is more preferable to mix a liquid medium of a recording liquid because a dispersion liquid for recording liquid can be directly produced.

  On the other hand, in the acid precipitation method, a part or all of the anionic group of the anionic group-containing organic polymer is neutralized with a basic compound, kneaded with a colorant such as carbon black in an aqueous medium, and acidic. A water-containing cake obtained by a process comprising a step of precipitating an anionic group-containing organic polymer by neutralizing or acidifying with a compound and adhering it to a pigment is obtained by using a basic compound to form an anionic group. This is a method of microencapsulation by neutralizing a part or all of it. By doing in this way, the aqueous dispersion containing the anionic microencapsulated pigment which is fine and contains many pigments can be manufactured.

  Examples of the solvent used for microencapsulation include alkyl alcohols such as methanol, ethanol, propanol, and butanol; aromatic hydrocarbons such as benzol, toluol, and xylol; methyl acetate, ethyl acetate, butyl acetate, and the like. Esters; Chlorinated hydrocarbons such as chloroform and ethylene dichloride; Ketones such as acetone and methyl isobutyl ketone; Ethers such as tetrahydrofuran and dioxane; Cellosolves such as methyl cellosolve and butyl cellosolve. The microcapsules prepared by the above method are once separated from these solvents by centrifugation or filtration, and then stirred and redispersed with water and the necessary solvent, and used for the intended present invention. A recording liquid that can be used is obtained. The average particle diameter of the encapsulated pigment obtained by the above method is preferably 50 nm to 180 nm.

  The self-dispersing pigment has at least one hydrophilic group bonded to the pigment surface directly or via another atomic group, and can be stably dispersed without using a dispersant. As the pigment having a hydrophilic group introduced on the surface thereof used in the present invention, those having ionicity are preferable, and those having an anionic charge or those having a cationic charge are suitable.

Examples of the anionic hydrophilic group include —COOM, —SO ₃ M, —PO ₃ HM, —PO ₃ M ₂ , —SO ₂ NH ₂ , —SO ₂ NHCOR (wherein M is a hydrogen atom, R represents an alkyl group having 1 to 12 carbon atoms, a phenyl group which may have a substituent, or a naphthyl group which may have a substituent. It is done. In the present invention, it is particularly preferable to use those in which —COOM and —SO ₃ M are bonded to the pigment surface.
Examples of a method for obtaining an anionically charged pigment include a method of oxidizing a pigment with sodium hypochlorite, a method of sulfonation, and a method of reacting a diazonium salt, but the present invention is not limited thereto. I don't mean.

  For example, a quaternary ammonium group can be used as the hydrophilic group bonded to the surface of the color pigment charged with a cation. More preferably, a pigment in which at least one of the quaternary ammonium groups listed below is bonded to the pigment surface is used.

  The content of the water-dispersible colorant in the ink is preferably 1 to 15% by mass and more preferably 2 to 10% by mass in terms of solid content. If the content is less than 1% by mass, the color developability and image density of the ink may be lowered, and if it exceeds 15% by mass, the ink may be thickened and the dischargeability may be deteriorated. Yes, and not economically desirable.

  As the colorant in the present invention, in addition to the resin-coated colorant / self-dispersing pigment, a pigment dispersed in an aqueous medium using a dispersant can also be used. When three types of resin-coated colorant, pigment dispersed in an aqueous medium using a dispersant, and self-dispersed pigment are used in combination, the pigment contained in the resin-coated colorant, the pigment dispersed by the dispersant, the self The total content of the dispersed pigment is preferably 3.0% by mass or more and 10.0% by mass or less. When the pigment content is less than 3.0% by mass, the image density may decrease, and when it exceeds 10% by mass, the ejection stability may decrease.

  As the dispersant, a polymer dispersant, a surfactant and the like can be used, and there is no particular limitation. From the viewpoint of pigment dispersion stability during storage, an alkali metal salt of a naphthalene sulfonic acid formalin condensate and It is preferable that the main component is an organic base salt.

  A water-soluble resin can be used as the polymer dispersant. Specific examples of water-soluble resins include styrene, styrene derivatives, vinyl naphthalene derivatives, aliphatic alcohol esters of α, β-ethylenically unsaturated carboxylic acids, acrylic acid, acrylic acid derivatives, maleic acid, maleic acid derivatives, itacon. Examples thereof include block copolymers consisting of at least two monomers selected from acids, itaconic acid derivatives, fumaric acid, fumaric acid derivatives, etc., random copolymers, or salts thereof. These water-soluble resins are alkali-soluble resins that are soluble in an aqueous solution in which a base is dissolved. Among these, those having a weight average molecular weight of 3000 to 20000 have a low viscosity of the dispersion when used in ink. It is particularly preferable because it has the advantage that it can be formed and can be easily dispersed.

The surfactant can be appropriately selected and used depending on the pigment type or ink formulation, and is generally classified into nonionic, anionic and amphoteric.
Examples of the nonionic surfactant include polyoxyethylene lauryl ether, polyoxyethylene myristyl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene alkyl ether such as polyoxyethylene oleyl ether, polyoxyethylene octylphenyl Ether, polyoxyethylene alkylphenyl ether such as polyoxyethylene nonylphenyl ether, polyoxyethylene-α-naphthyl ether, polyoxyethylene-β-naphthyl ether, polyoxyethylene monostyryl phenyl ether, polyoxyethylene distyryl phenyl ether , Polyoxyethylene alkyl naphthyl ether, polyoxyethylene monostyryl naphthyl ether, polyoxyethylene Range styryl naphthyl ether. In addition, surfactants such as polyoxyethylene polyoxypropylene block copolymers in which a part of polyoxyethylene of these surfactants is replaced with polyoxypropylene, and aromatic rings such as polyoxyethylene alkylphenyl ether A surfactant obtained by condensing a compound with formalin or the like can also be used.

  The nonionic surfactant has an HLB of preferably 12 to 19.5, more preferably 13 to 19. If the HLB is less than 12, there is a tendency for the dispersion stability to deteriorate due to poor conformity of the surfactant to the dispersion medium. If the HLB exceeds 19.5, the surfactant becomes difficult to adsorb to the pigment, so that the dispersion stability is also reduced. There is a tendency to deteriorate.

  Examples of the anionic surfactant include polyoxyethylene alkyl ether sulfate, polyoxyethylene alkyl phenyl ether sulfate, polyoxyethylene monostyryl phenyl ether sulfate, polyoxyethylene distyryl phenyl ether sulfate, and polyoxyethylene alkyl ether. Phosphate, polyoxyethylene alkyl phenyl ether phosphate, polyoxyethylene monostyryl phenyl ether phosphate, polyoxyethylene distyryl phenyl ether phosphate, polyoxyethylene alkyl ether carboxylate, polyoxyethylene alkyl phenyl Ether carboxylate, polyoxyethylene monostyryl phenyl ether carboxylate, polyoxyethylene distyryl phenyl ether carboxylate, naphthalene Sulfonate formalin condensate, melanin sulfonate formalin condensate, dialkyl sulfosuccinic acid ester salt, sulfosuccinic acid alkyl disalt, polyoxyethylene alkyl sulfosuccinic acid disalt, alkyl sulfoacetate, α-olefin sulphonate, alkylbenzene sulfone Acid salts, alkylnaphthalene sulfonates, alkyl sulfonates, N-acyl amino acid salts, acylated peptides, soaps and the like can be mentioned.

-Surfactant-
The ink of the present invention can contain a surfactant.
By adding a surfactant to the ink, the surface tension is reduced and the penetration of the ink droplets on the recording medium such as paper becomes faster, so that feathering and color bleeding can be reduced. Can do.

Surfactants are classified into nonionic, anionic and amphoteric depending on the polarity of the hydrophilic group.
Further, it is classified into fluorine type, silicone type, acetylene type, etc. according to the structure of the hydrophobic group.
In the present invention, it is preferable to mainly use a fluorine-based surfactant, and a silicone-based surfactant or an acetylene-based surfactant may be used in combination.
More preferably, a combined use of a fluorosurfactant and an acetylene glycol surfactant is preferred. Although the foam defoaming property is deteriorated by the addition of the surfactant, the influence of the bubble property is relatively small and the surface tension can be lowered by using these surfactants in combination.
When the surfactant is added to the ink as a penetrating agent, the addition amount is preferably 0.05 to 5% by mass, more preferably 0.1 to 3% by mass.

Examples of the fluorosurfactant include perfluoroalkyl sulfonate, perfluoroalkyl carboxylate, perfluoroalkyl phosphate ester, perfluoroalkyl ethylene oxide adduct, perfluoroalkyl betaine, perfluoroalkylamine oxide compound, etc. Is mentioned.
Examples of commercially available fluorine compounds generally include Surflon S-111, S-112, S-113, S121, S131, S132, S-141, S-144, and S-145 (Asahi Glass Co., Ltd.). , Fullrad FC-93, FC-95, FC-98, FC-129, FC-135, FC-170C, FC-430, FC-431, FC-4430 (manufactured by Sumitomo 3M), MegaFuck F-470, F-1405, F474 (manufactured by DIC), Zonyl FS-300, FSN, FSN-100, FSO, FSO-100 (manufactured by DuPont), F-top EF-351, 352, 801, 802 (manufactured by Gemco), FT-250, 251 (manufactured by Neos), PF-151N, PF-136A, PF-156A (manufactured by OMNOVA) and the like. That.
Among these, FSO, FSO-100, FSN, FSN-100, and FS-300 manufactured by Dupont are preferable because they can provide good print quality and storage stability.

Nonionic surfactants include, for example, polyols, glycol ethers, polyoxyethylene alkyl ethers, polyoxyethylene polyoxypropylene alkyl ethers, polyoxyethylene alkyl esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene alkylphenyl ethers, Examples include polyoxyethylene alkylamine, polyoxyethylene alkylamide, acetylene glycol and the like.
Examples of the anionic surfactant include polyoxyethylene alkyl ether acetate, dodecylbenzene sulfonate, laurate, polyoxyethylene alkyl ether sulfate, and the like.

Examples of the silicone surfactant include polyether-modified silicone compounds. Polyether-modified silicone compounds are side-chain type (pendant type) in which polyether group is introduced into the side chain of polysiloxy acid, one-end type in which polyether group is introduced into one end of polysiloxane, and both-end type in which both ends are introduced (ABA type), polysiloxane side-chain end-type with polysiloxane introduced on both side chain and both ends, polysiloxane (A) with polyether group introduced and unintroduced polysiloxane (B) repeated It can be classified into a bonded ABn type, a branched type in which a polyether group is introduced at the end of a branched polysiloxane, and the like.
Although there is no particular limitation in the present invention, a side chain type (pendant type) having a structure in which a polyether group is introduced into the side chain of polysiloxane is preferred.
Examples of commercially available products include KF-351A, KF-352A, KF-353, KF-354L, KF-355A, KF-615A, KF-945, KF-618, KF-6011, and KF-6015. KF-6004 (manufactured by Shin-Etsu Chemical Co., Ltd.), SF-3771, SF-8427, SF-8428, SH-3749, SH-8400, FZ-2101, FZ-2104, FZ-2118, FZ-2203, FZ- 2207, L-7604 (manufactured by Toray Dow Corning), BYK-345, BYK-346, BYK-348 (manufactured by Big Chemie Japan), and the like.

ただし、前記一般式（IV）式中、ｍ又はｎは、１以上の整数を表す。

ただし、前記一般式（Ｖ）式中、Ｒ₁及びＲ₂は、アルキル基を表す。

Examples of the acetylene surfactant include acetylene glycol surfactants and acetylene alcohol surfactants, and compounds represented by the following general formula (IV) or the following general formula (V) are preferable. Specific examples include compounds of the following formula (VI).
A combined use of a fluorine-based surfactant and an acetylene glycol-based surfactant represented by the formula (V) is more preferable. When the fluorosurfactant and the surfactant represented by the formula (V) are used in combination, when the fluorosurfactant is 1, the surfactant represented by the general formula (V) is 1 .50 or less is preferable.

However, in the general formula (IV), m or n represents an integer of 1 or more.

However, in the general formula (V), R ₁ and R ₂ represent an alkyl group.

  As the acetylene glycol surfactant or acetylene alcohol surfactant, commercially available products can be used. Examples of the commercially available products include Dynol 604 and Dynol 607 (manufactured by Air Products and Chemicals); NOL 104, SURFINOL 420, SURFINOL 440, SURFINOL SE (manufactured by Nissin Chemical Industry Co., Ltd.); Orphine E1004, Orphine E1010, Orphine EXP. Nissin Chemical Industry Co., Ltd.).

-Other ingredients-
Other components are not particularly limited and can be appropriately selected as necessary. For example, pH adjusters, foam inhibitors (antifoaming agents), antiseptic / antifungal agents, chelating reagents, rust preventives, oxidation Examples thereof include an inhibitor, an ultraviolet absorber, an oxygen absorber, and a light stabilizer.

<Foam suppressant>
In the present embodiment, the antifoaming agent is used to suppress foaming by adding a small amount to the ink. Here, foaming means that the liquid becomes a thin film and wraps air. Properties such as the surface tension and viscosity of the ink are involved in the generation of the bubbles. That is, a liquid having a high surface tension such as water is difficult to foam because a force that attempts to make the surface area of the liquid as small as possible works. On the other hand, highly viscous and highly permeable inks tend to foam due to their low surface tension, and bubbles generated by the viscosity of the solution are easily maintained and are difficult to defoam.

  Usually, the foam suppressor destroys the foam by locally lowering the surface tension of the foam film to destroy the foam or by interspersing the foam suppressor with a foam suppressor insoluble in the foam liquid. When using an extremely strong fluorosurfactant that lowers the surface tension as a surfactant in the ink, the surface tension of the foam film can be reduced locally even if the former foam suppressor is used. Because it cannot be used, it is not usually used. For this reason, an antifoaming agent that is insoluble in the latter foaming liquid is used. In this case, the stability of the ink is lowered by the antifoaming agent that is insoluble in the solution.

  On the other hand, the foam suppressor represented by the following general formula (VII) is not as strong as the fluorosurfactant in reducing the surface tension, but is highly compatible with the fluorosurfactant. For this reason, when the foam is efficiently incorporated into the foam film, the surface of the foam film is locally unbalanced due to the difference in surface tension between the fluorosurfactant and the foam suppressor, and the foam is destroyed. Conceivable.

  In the present embodiment, the antifoaming agent is preferably a compound represented by the general formula (VII). The content of the compound represented by the general formula (VII) is preferably 1.00 or less when the fluorine surfactant is 1.

［式（VII）中、Ｒ₁₀およびＲ₁₁は、独立に炭素原子３〜６個を有するアルキル基であり、Ｒ₁₂およびＲ₁₃は、独立に炭素原子１〜２個を有するアルキル基であり、ｎは１〜６の整数である。］

[In formula (VII), R ₁₀ and R ₁₁ are independently an alkyl group having 3 to 6 carbon atoms, and R ₁₂ and R ₁₃ are independently an alkyl group having 1 to 2 carbon atoms. , N is an integer of 1-6. ]

  Preferable examples of the compound represented by the general formula (VII) include 2,4,7,9-tetramethyldecane-4,7-diol, 2,5,8,11-tetramethyldodecane-5,8. -Diols. Particularly preferred is 2,4,7,9-tetramethyldecane-4,7-diol, which is effective not only for suppressing foam but also for improving wettability, and improving foam suppression and wettability. It is desirable to add it in order to achieve both.

  The content of the foam suppressor in the ink is preferably 0.01 to 10% by mass, and more preferably 0.1 to 5% by mass. When the content of the foam suppressor is less than 0.01% by mass, the effect of suppressing foam may not be obtained. When the content exceeds 10% by mass, the foam suppressive effect reaches its peak, and the viscosity, Ink physical properties such as particle size may be adversely affected.

  The pH adjuster is not particularly limited as long as it can adjust the pH to 7 to 11 without adversely affecting the ink to be prepared, and can be appropriately selected according to the purpose. And alkali metal element hydroxides, ammonium hydroxides, phosphonium hydroxides, alkali metal carbonates, and the like. If the pH is less than 7 or more than 11, the amount of the ink jet head or ink supply unit that melts out is large, and problems such as ink deterioration, leakage, and ejection failure may occur.

  Examples of the alcohol amines include diethanolamine, triethanolamine, 2-amino-2-ethyl-1,3-propanediol, and the like.

  Examples of the alkali metal hydroxide include lithium hydroxide, sodium hydroxide, and potassium hydroxide.

  Examples of the ammonium hydroxide include ammonium hydroxide, quaternary ammonium hydroxide, quaternary phosphonium hydroxide, and the like.

  Examples of the alkali metal carbonate include lithium carbonate, sodium carbonate, and potassium carbonate.

Examples of the antiseptic / antifungal agent include sodium dehydroacetate, sodium sorbate, 2-pyridinethiol-1-oxide sodium, sodium benzoate, sodium pentachlorophenol, and the like.
Examples of the chelating reagent include sodium ethylenediaminetetraacetate, sodium nitrilotriacetate, sodium hydroxyethylethylenediaminetriacetate, sodium diethylenetriaminepentaacetate, sodium uramil diacetate, and the like.

  Examples of the rust inhibitor include acidic sulfite, sodium thiosulfate, ammonium thiodiglycolate, diisopropylammonium nitrite, pentaerythritol tetranitrate, and dicyclohexylammonium nitrite.

  Examples of the antioxidant include phenolic antioxidants (including hindered phenolic antioxidants), amine-based antioxidants, sulfur-based antioxidants, phosphorus-based antioxidants, and the like.

  Examples of the phenolic antioxidants (including hindered phenolic antioxidants) include butylated hydroxyanisole, 2,6-di-tert-butyl-4-ethylphenol, stearyl-β- (3,5 -Di-tert-butyl-4-hydroxyphenyl) propionate, 2,2'-methylenebis (4-methyl-6-tert-butylphenol), 2,2'-methylenebis (4-ethyl-6-tert-butylphenol), 4,4′-Butylidenebis (3-methyl-6-tert-butylphenol), 3,9-bis [1,1-dimethyl-2- [β- (3-tert-butyl-4-hydroxy-5-methylphenyl) ) Propionyloxy] ethyl] 2,4,8,10-tetrixaspiro [5,5] undecane, 1,1,3-tris (2-methyl-) 4-hydroxy-5-tert-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, tetrakis [methylene- 3- (3 ′, 5′-di-tert-butyl-4′-hydroxyphenyl) propionate] methane, and the like.

  Examples of the amine-based antioxidant include phenyl-β-naphthylamine, α-naphthylamine, N, N′-di-sec-butyl-p-phenylenediamine, phenothiazine, N, N′-diphenyl-p-phenylenediamine. 2,6-di-tert-butyl-p-cresol, 2,6-di-tert-butylphenol, 2,4-dimethyl-6-tert-butyl-phenol, butylhydroxyanisole, 2,2′-methylenebis ( 4-methyl-6-tert-butylphenol), 4,4′-butylidenebis (3-methyl-6-tert-butylphenol), 4,4′-thiobis (3-methyl-6-tert-butylphenol), tetrakis [methylene -3 (3,5-di-tert-butyl-4-dihydroxyphenyl) propionate] meta 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, and the like.

  Examples of the sulfur-based antioxidant include dilauryl 3,3′-thiodipropionate, distearyl thiodipropionate, lauryl stearyl thiodipropionate, dimyristyl 3,3′-thiodipropionate, distearyl β. , β′-thiodipropionate, 2-mercaptobenzimidazole, dilauryl sulfide and the like.

  Examples of the phosphorus antioxidant include triphenyl phosphite, octadecyl phosphite, triisodecyl phosphite, trilauryl trithiophosphite, trinonylphenyl phosphite, and the like.

  Examples of the ultraviolet absorber include a benzophenone ultraviolet absorber, a benzotriazole ultraviolet absorber, a salicylate ultraviolet absorber, a cyanoacrylate ultraviolet absorber, and a nickel complex ultraviolet absorber.

  Examples of the benzophenone-based ultraviolet absorber include 2-hydroxy-4-n-octoxybenzophenone, 2-hydroxy-4-n-dodecyloxybenzophenone, 2,4-dihydroxybenzophenone, and 2-hydroxy-4-methoxybenzophenone. 2,2 ′, 4,4′-tetrahydroxybenzophenone, and the like.

  Examples of the benzotriazole ultraviolet absorber include 2- (2′-hydroxy-5′-tert-octylphenyl) benzotriazole, 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- (2′-hydroxy-4′-octoxyphenyl) benzotriazole, 2- (2′-hydroxy-3′-tert-butyl-5′-methylphenyl) -5-chlorobenzotriazole, and the like.

Examples of the salicylate-based ultraviolet absorber include phenyl salicylate, p-tert-butylphenyl salicylate, p-octylphenyl salicylate, and the like.
Examples of the cyanoacrylate ultraviolet absorber include ethyl-2-cyano-3,3′-diphenyl acrylate, methyl-2-cyano-3-methyl-3- (p-methoxyphenyl) acrylate, and butyl-2- And cyano-3-methyl-3- (p-methoxyphenyl) acrylate.

  Examples of the nickel complex-based ultraviolet absorber include nickel bis (octylphenyl) sulfide, 2,2′-thiobis (4-tert-octylferrate) -n-butylamine nickel (II), and 2,2′-thiobis. (4-tert-octyl ferrate) -2-ethylhexylamine nickel (II), 2,2′-thiobis (4-tert-octyl ferrate) triethanolamine nickel (II), and the like.

-Ink manufacturing method-
The ink of the present invention comprises a water-dispersible colorant, an organic solvent, a water-dispersible resin, a surfactant, a penetrating agent, water, and other components dispersed or dissolved in an aqueous medium as necessary. According to this, the mixture is mixed by stirring. This stirring and mixing can be performed by, for example, a sand mill, a homogenizer, a ball mill, a paint shaker, an ultrasonic disperser, and the like. The stirring and mixing is performed by a stirrer using a normal stirring blade, a magnetic stirrer, a high-speed disperser, or the like. be able to.

-Ink physical properties-
The physical properties of the ink of the present invention are not particularly limited and may be appropriately selected depending on the intended purpose. For example, the viscosity, surface tension and the like are preferably in the following ranges.

  The viscosity of the ink at 25 ° C. is preferably 5 to 25 mPa · s. More preferably, the viscosity at 25 ° C. is in the range of 6 to 20 mPa · s. By setting the ink viscosity to 5 mPa · s or more, the effect of improving the printing density and the character quality can be obtained. On the other hand, by suppressing the ink viscosity to 25 mPa · s or less, it is possible to ensure the discharge performance.

  Here, the said viscosity can be measured at 25 degreeC, for example using a viscometer (RE-550L, Toki Sangyo Co., Ltd. make).

The static surface tension of the ink is preferably 20 to 35 mN / m at 25 ° C., more preferably 20 to 27 mN / m. By setting the surface tension to 27 mN / m or less, the ink can spread on the paper and high image density can be obtained.
Furthermore, when the dynamic surface tension is 25 ° C., the dynamic surface tension at the surface lifetime of 15 ms by the maximum bubble pressure method is preferably 35 mN / m or less, more preferably 33 mN / m or less. When the dynamic surface tension at a surface life of 15 ms is 35 mN / m or less, the general-purpose printing paper has good wettability and penetrability, and is highly effective in reducing beading and color bleeding. In addition, the color development and white spots of plain paper are improved. The ink may be used by being contained in a container such as an ink cartridge.

  The ink of the present invention, as an inkjet head, uses a piezoelectric element as pressure generating means for pressurizing the ink in the ink flow path to deform the diaphragm that forms the wall surface of the ink flow path, thereby changing the volume in the ink flow path. A so-called piezo type that discharges ink droplets (refer to Japanese Patent Laid-Open No. 2-51734), or a so-called thermal type that generates bubbles by heating ink in an ink flow path using a heating resistor ( JP, 61-59911, A), the diaphragm which forms the wall surface of an ink channel, and an electrode are arranged opposite, and a diaphragm is deformed by the electrostatic force generated between a diaphragm and an electrode, For printers equipped with any ink jet head such as an electrostatic type (see Japanese Patent Laid-Open No. 6-71882) that discharges ink droplets by changing the volume in the ink flow path Can also be used well.

  The image-formed product of the present invention is an image-formed product having the ink image of the present invention on a recording medium, wherein the ink image contains a colorant, anionic urethane resin particles, and an amine compound, and the amine compound Is an organic amine compound having a boiling point of 120 ° C. or more and 200 ° C. or less and a molecular weight of 100 or less, and the content of the amine compound is 0.01 or more and 1. 00 or less, and has an image formed on the recording medium using the ink of the present invention.

<Recording media>
The recording medium is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include plain paper, glossy paper, special paper, cloth, film, OHP sheet, and general-purpose printing paper. These may be used individually by 1 type and may use 2 or more types together.

  The image-formed product has high image quality, no bleeding, is excellent in stability over time, and can be suitably used for various purposes as a material on which various prints or images are recorded.

<Image Forming Method and Image Forming Apparatus>
The image forming method of the present embodiment includes at least an ink flying process, and further includes other processes appropriately selected as necessary, for example, a stimulus generation process, a control process, and the like. The image forming apparatus according to the present exemplary embodiment includes at least an ink flying unit, and further includes other units selected as necessary, for example, a stimulus generation unit, a control unit, and the like. The image forming method of the present embodiment can be preferably carried out by the image forming apparatus of the present embodiment, and the ink flying step can be suitably carried out by the ink flying means. Moreover, the said other process can be suitably performed by the said other means.

-Ink flying process (an example of an image forming process)-
In the ink flying process in the image forming method of the present embodiment, at least one kind of stimulus (energy) selected from heat, pressure, and vibration is applied to the ink, and the ink is ejected onto the recording medium. And forming an image. Any known ink jet recording method can be applied as a method for forming an image on a printing paper by ejecting ink onto the printing paper in this ink flying process. Examples of such a method include an ink jet recording method in which a head is scanned, and an ink jet recording method in which an image is recorded on a certain sheet of printing paper by using a lined head.

  In this ink flying process, there is no particular limitation on the driving method of the recording head, which is an ink flying means, a piezoelectric element actuator using PZT, a method of applying thermal energy, an on-demand using an actuator using electrostatic force, etc. A recording head can be used, and recording can be performed with a continuous ejection type charge control type head.

  In the image forming method of the present invention, the recording medium on which the ink has been ejected can be provided with a heat drying step as necessary. In this case, the printing paper can be dried by an infrared drying device, a microwave drying device, a roll heater, a drum heater or hot air. Further, as a method for smoothing the image forming surface and fixing the image, a fixing step of heating to 100 ° C. to 150 ° C. by a heating means and heat fixing may be provided. By providing this fixing step, the glossiness and fixing property of the image formed product are improved. Here, as the heat fixing means, a roller having a heated mirror surface, a drum heater or the like is preferably used, and the mirror surface portion (smooth portion) of the roll heater or drum heater can be brought into contact with the image forming surface. As for the heating temperature, a fixing roller heated to 100 to 150 ° C. is preferable in view of image quality, safety and economy.

  An example of the image forming method and the image forming apparatus of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic diagram of an inkjet image forming apparatus to which the present invention is applied. An inkjet image forming apparatus 300 to which the present invention is applied includes a recording medium transport unit 301, a pretreatment process unit 302 that applies a pretreatment liquid to a recording medium (recording medium) 203, an image formation process unit 304, and a post-image formation process. The post-processing step unit 305 applies a post-processing liquid to the recording medium.

  The recording medium conveyance unit 301 includes a paper feeding device 307, a plurality of conveyance rollers, and a winding device 308. 1 is continuous paper (roll paper) wound in a roll shape. The recording medium 203 is unwound from a paper feeding device by a conveyance roller, conveyed on a platen, and wound by a winding device 308. Taken.

  The recording medium 203 conveyed from the recording medium conveying unit 301 is applied with a pretreatment liquid in the pretreatment step unit 302 of FIG. In inkjet, when an image is formed on a recording medium other than dedicated inkjet paper, quality problems such as bleeding, density, color tone and show-through, and problems related to image fastness such as water resistance and weather resistance occur. As a means for solving the problem, a technique for improving image quality by applying a pretreatment liquid having a function of aggregating ink before forming an image on a recording medium is performed.

  The pretreatment process may be any coating method in which the above pretreatment liquid is uniformly applied to the surface of the printing paper, and is not particularly limited. Examples of such coating methods include blade coating, gravure coating, gravure offset coating, bar coating, roll coating, knife coating, air knife coating, comma coating, U comma coating, and AKKU coating. , Smoothing coating method, micro gravure coating method, reverse roll coating method, 4 to 5 roll coating method, dip coating method, curtain coating method, slide coating method, die coating method and the like.

  FIG. 2 is a schematic diagram of the pretreatment process unit 302 in the present embodiment. In this embodiment, the roll coating method will be described, but another pretreatment liquid coating method may be used.

As shown in the figure, the recording medium 203 such as continuous paper is conveyed into the pretreatment liquid coating apparatus 204 by the conveyance roller 201. The pretreatment liquid application device 204 stores a pretreatment liquid 205, and the pretreatment liquid 205 is transferred to the roller surface of the application roller 208 by a stirring / supply roller 206 and a transfer / thinning roller 207 in a thin film shape. .
The application roller 208 rotates while being pressed against the rotating platen roller 202, and the recording medium 203 passes through the application roller 208 to apply the pretreatment liquid 205 to the surface.

  Further, the platen roller 202 can adjust the nip pressure when applying the pretreatment liquid by the pressure adjusting device 209. By changing the nip pressure, the coating amount of the pretreatment liquid 205 can be changed. Further, the application amount can be adjusted by changing the rotation speed of the application roller 208 and the platen roller 202. The application roller 208 and the platen roller 202 are driven by a power source such as a drive motor (not shown), and the amount of application can be adjusted by changing the rotational speed by changing the energy of the power source.

  As described above, the method of applying the pretreatment liquid 205 for improving the image quality to the recording area of the recording medium 203 with the application roller 208 is a method of performing the processing by spraying the processing agent liquid onto the recording medium using the ejection head. Compared to the above, the pretreatment liquid 205 having a relatively high viscosity can be applied thinly on the recording medium 203, and image bleeding and the like can be further reduced.

Moreover, you may provide the pre-processing post-drying part 303 in the pre-processing part after an application | coating process like FIG.
The pre-processing and post-drying apparatus includes, for example, heat rollers 311 and 312 as shown in FIG. According to this apparatus, the continuous paper coated with the pretreatment liquid is transported to the heat roller by the transport roller. The heat roller is heated to a high temperature of 50 to 100 ° C., and the continuous paper coated with the pretreatment liquid evaporates and is dried by contact heat transfer from the heat roller. The drying means is not limited to this, and an infrared drying device, a microwave drying device, a hot air device, etc. can also be applied. Instead of using a single device, for example, a heat roller and a hot air device are combined. Also good. Although not shown, it is also effective to heat the recording medium (addition of a preheating step) before applying the pretreatment liquid.

  On the recording medium after the pretreatment process, an image corresponding to the image data is formed in the image forming process section.

The image forming process unit 304 is a full-line head, and four recording heads 304K that can handle black (K), cyan (C), magenta (M), and yellow (Y) from the upstream side in the recording medium conveyance direction. , 304C, 304M, and 304Y. For example, in the black (K) recording head 304K, four head units 304K-1, 304K-2, 304K-3, and 304K-4 that are short in the direction orthogonal to the transport direction are arranged in a staggered manner as shown in FIG. This ensures the print area width. FIG. 4 is an enlarged view of the head unit 304K-1. As shown in the drawing, a large number of print nozzles 310 are arranged on the nozzle surface 309 of 304K-1 along the longitudinal direction of the head unit 304K-1, thereby constituting a nozzle row. In this embodiment, the number of nozzle rows is one, but a plurality of rows can be provided. The other recording heads 304C, 304M, and 304Y have the same configuration, and the four recording heads 304K, 304C, 304M, and 304Y are arranged in the transport direction while maintaining the same pitch. As a result, it is possible to form an image over the entire width of the print area with a single recording operation.
The type of ink is not limited to K, C, M, and Y, and photo ink such as light cyan can be applied.

  The post-processing liquid is applied to the recording medium after the image forming process by the post-processing process unit 305. This post-treatment liquid described later contains a component capable of forming a transparent protective layer on the recording medium.

  In the post-processing step in the present embodiment, it may be applied over the entire image surface of the recording medium, or may be applied only to a specific portion of the image surface. More preferably, it is desirable to change the coating amount and the coating method according to the printing conditions (the type of recording medium, the amount of ink ejected onto the paper, etc.).

The method for applying the post-treatment liquid is not particularly limited, and various methods are appropriately selected depending on the type of the post-treatment liquid. The same method as the method for applying the pre-treatment liquid or the above inkjet ink is allowed to fly. Any of the methods similar to the method can be preferably used. Among these, a method similar to the method of flying an inkjet ink is particularly preferable from the viewpoint of the apparatus configuration and the storage stability of the post-treatment liquid. By using this method, it is possible to apply a necessary amount to an arbitrary location on the image. In this post-process includes the steps of dry coverage in the image formed surface to form a protective layer by applying a post-treatment liquid containing a transparent resin so as to 0.5g / m ² ~10g / m ² is there.

Dry coverage of the post-treatment solution is preferably ^{0.5g / m 2 ~10g / m 2} , more preferably ^{2g / m 2 ~8g / m 2} . When the adhesion amount is less than 0.5 g / m ² , the image quality (image density, saturation, glossiness and fixability) is hardly improved, and when it exceeds 10 g / m ² , the drying property of the protective layer is increased. And the image quality improvement effect is saturated, which is economically disadvantageous.

  Further, the post-processing section 306 may be provided with a post-processing post-drying section 306 as shown in FIG. The post-processing post-drying apparatus includes, for example, heat rollers 313 and 314 as shown in FIG. According to this apparatus, the continuous paper coated with the post-treatment liquid is conveyed to the heat roller by the conveyance roller. The heat roller is heated to a high temperature, and the continuous paper coated with the post-treatment liquid is dried due to evaporation of moisture by contact heat transfer from the heat roller. The drying means is not limited to this, and an infrared drying device, a microwave drying device, a hot air device, etc. can also be applied. Instead of using a single device, for example, a heat roller and a hot air device are combined. Also good. The paper after drying is taken up by the take-up device 308. If the pressure during the take-up is large, the image may be transferred to the back side. In that case, a pre-winding drying section 315 as shown in FIG. 1 can be provided as necessary. In addition, the structure (for example, combination of a heat roller and a warm air apparatus etc.) described above is applicable also to this drying means.

<Head structure>
Next, an example of a droplet discharge head constituting the recording head in this image forming apparatus will be described with reference to FIGS. 5 is a cross-sectional explanatory view along the longitudinal direction of the liquid chamber of the head, and FIG. 6 is a cross-sectional explanatory view of the head along the lateral direction of the liquid chamber (nozzle arrangement direction).

  The droplet discharge head includes a flow channel plate 401 formed by anisotropic etching a single crystal silicon substrate, a vibration plate 402 formed by nickel electroforming, for example, bonded to the lower surface of the flow channel plate 401, and a flow plate. A nozzle plate 403 that is bonded to the upper surface of the path plate 401 is bonded and stacked, and the nozzle communication path 405, the liquid chamber 406, and the liquid chamber, which are channels through which the nozzles 404 that discharge liquid droplets (ink droplets) communicate with each other. An ink supply port 409 communicating with a common liquid chamber 408 for supplying ink to 406 is formed.

  In addition, two rows (only one row is shown in FIG. 4) of stacked piezoelectric elements as electromechanical conversion elements which are pressure generating means (actuator means) for deforming the diaphragm 402 to pressurize the ink in the liquid chamber 406. An element 421 and a base substrate 422 to which the piezoelectric element 421 is bonded and fixed are provided. Note that a column portion 423 is provided between the piezoelectric elements 421. The column portion 423 is a portion formed at the same time as the piezoelectric element 421 by dividing the piezoelectric element member. However, since the drive voltage is not applied, the column portion 423 becomes a simple column.

  In addition, an FPC cable 224 for connecting to a drive circuit (drive IC) (not shown) is connected to the piezoelectric element 421.

Then, the peripheral edge of the diaphragm 402 is joined to the frame member 430, and the frame member 430 serves as a through-hole 431 and a common liquid chamber 408 that accommodates an actuator unit including the piezoelectric element 421 and the base substrate 422. A recess and an ink supply hole 432 for supplying ink from the outside to the common liquid chamber 408 are formed. The frame member 430 is formed by injection molding with a thermosetting resin such as an epoxy resin or polyphenylene sulfite, for example.
Here, the flow path plate 401 is formed by, for example, anisotropically etching a single crystal silicon substrate having a crystal plane orientation (110) with an alkaline etching solution such as an aqueous potassium hydroxide solution (KOH), thereby connecting the nozzle communication path 405, Although a recess or a hole to be the liquid chamber 406 is formed, the invention is not limited to a single crystal silicon substrate, and other stainless steel substrates, photosensitive resins, and the like can also be used.

  The diaphragm 402 is formed of a nickel metal plate, and is manufactured by, for example, an electroforming method (electroforming method). In addition, a metal plate or a joining member between a metal and a resin plate may be used. it can. The piezoelectric element 421 and the column 423 are bonded to the diaphragm 402 with an adhesive, and the frame member 430 is bonded to the diaphragm 402 with an adhesive.

  The nozzle plate 403 forms a nozzle 404 having a diameter of 10 to 30 μm corresponding to each liquid chamber 406 and is bonded to the flow path plate 401 with an adhesive. This nozzle plate 403 is formed by forming a water repellent layer on the outermost surface through a required layer on the surface of a nozzle forming member made of a metal member.

  The piezoelectric element 421 is a stacked piezoelectric element (here, PZT) in which piezoelectric materials 451 and internal electrodes 452 are alternately stacked. An individual electrode 453 and a common electrode 454 are connected to each internal electrode 452 drawn to the alternately different end faces of the piezoelectric element 421. In this embodiment, the ink in the liquid chamber 406 is pressurized using the displacement in the d33 direction as the piezoelectric direction of the piezoelectric element 421. However, the pressure in the d31 direction is used as the piezoelectric direction of the piezoelectric element 421. The ink in the liquid chamber 406 may be pressurized. Alternatively, a structure in which one row of piezoelectric elements 421 is provided on one substrate 422 may be employed.

  In the droplet discharge head configured as described above, for example, the voltage applied to the piezoelectric element 421 is lowered from the reference potential, the piezoelectric element 421 contracts, and the diaphragm 402 descends to expand the volume of the liquid chamber 406. Then, the ink flows into the liquid chamber 406, and then the voltage applied to the piezoelectric element 421 is increased to extend the piezoelectric element 421 in the laminating direction, and the diaphragm 402 is deformed in the nozzle 404 direction to change the volume / volume of the liquid chamber 406. By contracting the volume, the recording liquid in the liquid chamber 406 is pressurized, and droplets of the recording liquid are ejected (jetted) from the nozzle 404.

  Then, by returning the voltage applied to the piezoelectric element 421 to the reference potential, the diaphragm 402 is restored to the initial position, and the liquid chamber 406 expands to generate a negative pressure. The recording liquid is filled in 406. Therefore, after the vibration of the meniscus surface of the nozzle 404 is attenuated and stabilized, the operation proceeds to the next droplet discharge.

  Note that the driving method of the head is not limited to the above example (drawing-pushing), and striking or pushing can be performed depending on the direction of the drive waveform.

  Further, in this example, a piezoelectric element is used as a pressure generating means for pressurizing ink in the ink flow path, and a diaphragm that forms the wall surface of the ink flow path is deformed to change the volume in the ink flow path to discharge ink droplets. A so-called piezo-type one is applied (refer to Japanese Patent Laid-Open No. 2-51734). However, a so-called thermal-type one that generates bubbles by heating ink in an ink flow path using a heating resistor (Japanese Patent Laid-Open No. 61-61). No. -59911), the diaphragm and the electrode forming the wall surface of the ink flow path are arranged opposite to each other, and the diaphragm is deformed by an electrostatic force generated between the vibration plate and the electrode, whereby the ink flow path inner volume is obtained. It is also possible to apply an electrostatic type (see Japanese Patent Laid-Open No. 6-71882) or the like that discharges ink droplets by changing.

  Examples of the present invention will be described below, but the present invention is not limited to these examples. Unless otherwise specified, “parts” means “parts by mass” in the following description.

<< Examples 1 to 25, Comparative Examples 1 to 6 >>
<Ink adjustment>
(Preparation Example 1)
-Preparation of surface-modified black pigment dispersion 1 (self-dispersed pigment dispersion 1)-
100 g of Black Pearls (registered trademark) 1000 (carbon black having a BET surface area of 343 m ² / g and DBPA 105 mL / 100 g), 100 mmol of sulfanilic acid and 1 L of ion-exchanged high-purity water were mixed in a Silverson mixer (6000 rpm) at room temperature. If the pH of the resulting slurry is higher than 4, 100 mmol of nitric acid is added. After 30 minutes, sodium nitrite (100 mmol) dissolved in a small amount of ion-exchanged high purity water was slowly added to the above mixture. Furthermore, it heated at 60 degreeC, stirring, and was made to react for 1 hour. A modified pigment with sulfanilic acid added to carbon black was produced. Subsequently, the modified pigment dispersion was obtained after 30 minutes by adjusting the pH to 9 with a 10% tetrabutylammonium hydroxide solution (methanol solution). Perform ultrafiltration using a dialysis membrane using a dispersion containing a pigment bound to at least one sulfanilic acid group or sulfanilic acid tetrabutylammonium salt and ion-exchanged high-purity water, and further ultrasonically disperse the pigment solids. A modified pigment dispersion having a concentration of 20% was obtained. The surface treatment level was 0.75 mmol / g, and the particle diameter (D50) measured with a particle size distribution analyzer (Nikkiso Co., Ltd., Nanotrac UPA-EX150) was 120 nm.

(Preparation Example 2)
-Preparation of surface-modified black pigment dispersion 2 (self-dispersed pigment dispersion 2)-
Add 1L of ion-exchange high purity water and 1 mol of 4-aminobenzoic acid to 500g of Black Pearls (registered trademark) 880 (carbon black with BET surface area of 220m ² / g and DBPA 105mL / 100g) manufactured by Cabot Corporation to ProcessAll 4HV mixer (4L) did. The mixture was then mixed vigorously at 300 rpm while warming to 60 ° C. for 10 minutes. To this was added 20% aqueous sodium nitrite solution [1 molar equivalent based on 4-aminobenzoic acid] over 15 minutes. The mixture was stirred for 3 hours while heating to 60 ° C. The reaction product was taken out while being diluted with 750 mL of ion-exchange high purity water. Subsequently, the modified pigment dispersion was obtained after 30 minutes by adjusting the pH to 9 with a 10% tetrabutylammonium hydroxide solution (methanol solution). The obtained dispersion containing a pigment combined with at least one aminobenzoic acid group or aminobenzoic acid tetrabutylammonium salt is subjected to ultrafiltration using a dialysis membrane using ion-exchange high-purity water, and further subjected to ultrasonic dispersion. And a modified pigment dispersion having a pigment solid content of 20% was obtained. The surface treatment level was 0.5 mmol / g, and the particle diameter (D50) measured by a particle size distribution measuring device (Nikkiso Co., Ltd., Nanotrac UPA-EX150) was 104 nm.

(Preparation Example 3)
<Preparation of carbon black pigment-containing polymer fine particle dispersion 3 (Preparation of resin-coated pigment dispersion 3)>
-Preparation of polymer solution A-
After sufficiently replacing the inside of a 1 L flask equipped with a mechanical stirrer, thermometer, nitrogen gas inlet tube, reflux tube, and dropping funnel, 11.2 g of styrene, 2.8 g of acrylic acid, 12.0 g of lauryl methacrylate Then, 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, 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, azobismethylvalero A mixed solution of 2.4 g of nitrile and 18 g of methyl ethyl ketone was dropped into the flask over 2.5 hours. After dropping, a mixed solution of 0.8 g of azobismethylvaleronitrile and 18 g of methyl ethyl ketone was dropped into the flask over 0.5 hours. After aging at 65 ° C. for 1 hour, 0.8 g of azobismethylvaleronitrile was added and further aging was performed for 1 hour. After completion of the reaction, 364 g of methyl ethyl ketone was added to the flask to obtain 800 g of a polymer solution A having a concentration of 50% by mass.

-Preparation of carbon black pigment-containing polymer fine particle dispersion 3-
28 g of polymer solution A, C.I. I. 42 g of carbon black (manufactured by Degussa, FW100), 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 sufficiently stirred and then kneaded using a roll mill. The obtained paste was put into 200 g of pure water and stirred sufficiently, and then methyl ethyl ketone and water were distilled off using an evaporator, and this dispersion was further removed with polyvinylidene fluoride having an average pore size of 5.0 μm to remove coarse particles. By pressure filtration with a membrane filter, a carbon black pigment-containing polymer fine particle dispersion having a pigment solid content of 15% by mass and a solid content concentration of 20% by mass was obtained. The particle size (D50) of the polymer particles in the carbon black pigment-containing polymer particle dispersion was measured with a particle size distribution analyzer (Nikkiso Co., Ltd., Nanotrac UPA-EX150) and found to be 104 nm.

(Preparation Example 4)
<Preparation of cyan resin-coated pigment dispersion 4>
20 g of organic solvent (methyl ethyl ketone), 0.03 g of polymerization chain transfer agent (2-mercaptoethanol), polymerization initiator, 10 g of methacrylic acid, 22.5 g of styrene monomer, 2.5 g of polyethylene glycol monomethacrylate (ethylene oxide = 15), polyethylene 5 g of glycol / propylene glycol monomethacrylate (ethylene oxide = 5, propylene oxide = 7) and 10 g of styrene macromonomer were placed in a reaction vessel sufficiently substituted with nitrogen gas and polymerized with stirring at 75 ° C. Dissolved. Further, 0.9 g of 2,2′-azobis (2,4-dimethylvaleronitrile) was added and aged at 80 ° C. for 1 hour to obtain a water-insoluble polymer solution (1).
5 g obtained by drying the polymer solution obtained as the water-insoluble polymer solution (1) under reduced pressure was dissolved in 15 g of methyl ethyl ketone, and the polymer was neutralized using an aqueous sodium hydroxide solution. Furthermore, C.I. I. 15 g of Pigment Blue 15: 3 was added and kneaded with a disperser while adding water.
After adding 100 g of ion-exchanged water to the obtained kneaded product and stirring, the methyl ethyl ketone was removed at 60 ° C. under reduced pressure, and a part of the water was further removed, whereby a cyan resin-coated type having a solid content concentration of 15% by mass. A pigment dispersion was obtained. (Pigment: Water-insoluble polymer = 1: 0.3) The volume average particle diameter of the pigment in this dispersion was 91 nm.

(Preparation Example 5)
<Black surfactant-dispersed pigment dispersion 1>
175 parts by mass of carbon black (NIPEX 160, manufactured by Degussa, BET specific surface area of 150 m ² / g,
(Average primary particle size 20 nm, pH 4.0, DBP oil absorption 620 g / 100 g)
175 parts by mass of sodium naphthalene sulfonate formalin condensate (Pionine A-45-PN, Naphthalene sulfonic acid dimer, Takemoto Yushi Co., Ltd.,
(Total content of trimer and tetramer = 50 mass%)
650 parts by mass of distilled water The above mixture was premixed to prepare a mixed slurry (a). This was circulated and dispersed in a disk type media mill (manufactured by Ashizawa Finetech Co., Ltd., DMR type) using 0.05 mm zirconia beads and a filling rate of 55% at a peripheral speed of 10 m / s and a liquid temperature of 10 ° C. for 3 minutes. Coarse particles were centrifuged with a centrifuge (Model 7700, manufactured by Kubota Corporation) to obtain a surfactant-dispersed pigment dispersion 1 having a pigment concentration of 13% by mass.

(Preparation Example 6)
-Preparation of aqueous dispersion of polyurethane resin 1-
In a simple pressure reactor equipped with a stirrer and a heater, 287.9 parts of crystalline polycarbonate diol of Mn 2,000 [Duranol T6002, manufactured by Asahi Kasei Chemicals Co., Ltd.], 3.6 parts of 1,4 butanediol, DMPA (Dimethylolpropionic acid) 8.9 parts, hydrogenated MDI 98.3 parts and acetone 326.2 parts were charged while introducing nitrogen. Thereafter, the mixture was heated to 90 ° C. and subjected to urethanization reaction for 8 hours to produce a prepolymer.
The reaction mixture was cooled to 40 ° C., 10.0 parts of triethylamine was added and mixed, 568.8 parts of water was further added, and the mixture was emulsified with a rotor-stator type mechanical emulsifier to obtain an aqueous dispersion. . 28.1 parts of 10% ethylenediamine aqueous solution was added to the obtained aqueous dispersion with stirring, and the mixture was stirred at 50 ° C. for 5 hours to carry out chain elongation reaction.
Thereafter, acetone was removed at 65 ° C. under reduced pressure to adjust the water content to obtain an aqueous dispersion of polyurethane resin 1 having a solid content of 40% by mass. The particle size (D50) of the aqueous dispersion of polyurethane resin 1 was 9 nm as measured with a particle size distribution measuring device (Nanotrack UPA-EX150, manufactured by Nikkiso Co., Ltd.).

(Preparation Example 7)
-Preparation of aqueous dispersion of polyurethane resin 2-
An aqueous dispersion of polyurethane resin 2 was obtained in the same manner as in Preparation Example 6 except that the amount of triethylamine added was changed to 8.9 parts. The particle size (D50) of the aqueous dispersion of polyurethane resin 2 was 23 nm as measured by a particle size distribution analyzer (Nanotrack UPA-EX150, manufactured by Nikkiso Co., Ltd.).

(Preparation Example 8)
-Preparation of aqueous dispersion of polyurethane resin 3-
An aqueous dispersion of polyurethane resin 3 was obtained in the same manner as in Preparation Example 6 except that the amount of triethylamine added was changed to 7.9 parts. The particle size (D50) of the aqueous dispersion of polyurethane resin 3 was 34 nm as measured by a particle size distribution analyzer (Nanotrack UPA-EX150, manufactured by Nikkiso Co., Ltd.).

(Preparation Example 9)
-Preparation of aqueous dispersion of polyurethane resin 4-
An aqueous dispersion of polyurethane resin 4 was obtained in the same manner as in Preparation Example 6 except that the amount of triethylamine added was changed to 6.8 parts. The particle size (D50) of the aqueous dispersion of polyurethane resin 4 was 49 nm as measured with a particle size distribution analyzer (Nanotrack UPA-EX150, manufactured by Nikkiso Co., Ltd.).

(Preparation Example 10)
-Preparation of aqueous dispersion of polyurethane resin 5-
An aqueous dispersion of polyurethane resin 5 was obtained in the same manner as in Preparation Example 6 except that the amount of triethylamine added was changed to 4.9 parts. The particle size (D50) of the aqueous dispersion of polyurethane resin 5 was 70 nm as measured by a particle size distribution analyzer (Nanotrack UPA-EX150, manufactured by Nikkiso Co., Ltd.).

(Preparation Example 11)
-Preparation of aqueous dispersion of polyurethane resin 6-
An aqueous dispersion of polyurethane resin 6 was obtained in the same manner as in Preparation Example 6 except that the amount of triethylamine added was changed to 5.7 parts. The particle size (D50) of the aqueous dispersion of polyurethane resin 6 was 89 nm as measured with a particle size distribution analyzer (Nanotrack UPA-EX150, manufactured by Nikkiso Co., Ltd.).

(Preparation Example 12)
-Preparation of aqueous dispersion of polyurethane resin 7-
An aqueous dispersion of polyurethane resin 7 was obtained in the same manner as in Preparation Example 6 except that the amount of triethylamine added was changed to 7.0 parts. The particle size (D50) of the aqueous dispersion of polyurethane resin 7 was 121 nm as measured by a particle size distribution analyzer (Nikkiso Co., Ltd., Nanotrac UPA-EX150).

(Preparation Example 13)
-Preparation of acrylic-silicone resin aqueous dispersion 1-
A 1 L flask equipped with a mechanical stirrer, thermometer, nitrogen gas inlet tube, reflux tube, and dropping funnel was sufficiently purged with nitrogen gas, and then added 17.5 g of Latemule S-180 and 350 g of ion-exchanged water. The temperature was raised to 65 ° C.
After the temperature increase, 3.0 g of t-butyl peroxobenzoate and 1.0 g of sodium isoascorbate as reaction initiators were added, and after 5 minutes, 45 g of methyl methacrylate, 160 g of 2-ethylhexyl methacrylate, 5 g of acrylic acid, methacrylic acid, 45 g of butyl acid, 30 g of cyclohexyl methacrylate, 15 g of vinyltriethoxysilane, 8.0 g of Latemule S-180, and 340 g of ion-exchanged water were mixed and dropped over 3 hours. Then, after heat aging at 80 ° C. for 2 hours, the mixture was cooled to room temperature and the pH was adjusted to 7-8 with sodium hydroxide. Ethanol was distilled off using an evaporator and the water content was adjusted to prepare 730 g of an acrylic silicone resin aqueous dispersion 1 solution having a solid content of 40% by mass. With respect to the acrylic silicone resin aqueous dispersion 1, the particle diameter (D50) was 43 nm as measured by a particle size distribution analyzer (Nikkiso Co., Ltd., Nanotrac UPA-EX150).

<Examples and comparative examples>
-Preparation of ink-
The resin particle content shown below is all solid content.
<Example 1>
In a container equipped with a stirrer, 20.00 parts by mass of 1.3-butanediol, 10.00 parts by mass of 3-methyl-1.3-butanediol, 8.00 parts by mass of glycerin and 2-ethyl-1.3-hexane Add 2.00 parts by mass of diol and 0.50 parts by mass of surfactant, and stir for about 30 minutes to make uniform. Next, 37.50 parts by mass and high-purity water are added to the self-dispersing pigment dispersion 1, and the mixture is stirred for about 60 minutes to make it uniform. Further, 4.50 parts by mass of polyurethane resin 4 (Preparation Example 9) is added and stirred for 30 minutes to make the ink uniform. This ink was subjected to pressure filtration through a polyvinylidene fluoride membrane filter having an average pore diameter of 1.2 μm to remove coarse particles and dust, and thus the ink of Example 1 was produced. High purity water was added so that the total amount would be 100 parts by mass.
As the surfactant, the following fluorosurfactant FS-300 was used.
* Fluorosurfactant FS-300
(Polyoxyalkylene (C ₂ ~C ₃₎ -2- perfluoroalkyl (C ₄ -C ₁₆₎
Ethyl ether)
(DuPont product name "FS-300", solid content 40%)

<Examples 2 to 25 and Comparative Examples 1 to 6>
In the same manner as in Example 1, the water-soluble organic solvent and surfactant shown in Tables 1 to 3 below were mixed and stirred, and a water-dispersible colorant (pigment dispersion) and high-purity water were added and mixed and stirred. The dispersible resin is mixed and stirred to make the ink uniform. In Examples 20 to 25, the antifoaming agent is added and is added together with the surfactant. The following foam inhibitors were used.
* Foam suppressor ENVIRO GEM AD01
2,4,7,9-Tetramethyl-4,7-decandiol Nissin Chemical Industry Co., Ltd., trade name "Envirogem AD01"
See Table for addition amount. In Example 24, not only the above-mentioned fluorine-based surfactant FS-300 but also an acetylene glycol-based surfactant is added as a surfactant.
* Acetylene glycol surfactants:
For the amount of 2,4,7,9-tetramethyl-5-decyne-4,7-diol added, see the table. This ink was filtered under pressure with a polyvinylidene fluoride membrane filter having an average pore size of 1.2 μm, Coarse particles and dust were removed to prepare inks of Examples 2 to 25 and Comparative Examples 1 to 6.

* Polyester urethane resin: Sanyo Chemical Industries UWS-145
Particle size D50 = 17 nm / solid content 31.4%
* Polyether urethane resin: Takelac W5661
Particle size D50 = 15.4 nm / solid content 34.8%

Next, the ink physical properties of the inks of Examples 1 to 25 and Comparative Examples 1 to 6 were measured by the following evaluation method. The results are shown in Table 4.
-Ink physical properties-
<Ink viscosity measurement>
The viscosity of the ink was measured at 25 ° C. using a viscometer (RE-550L, manufactured by Toki Sangyo Co., Ltd.).

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

<Particle size (D50)>
Using a particle size distribution measuring apparatus (Nikkiso Co., Ltd., Nanotrac UPA-EX150), the pigment particle diameter (D50) was measured by diluting with pure water so that the solid content concentration was 0.01% by mass.

<Flowability during water evaporation>
The inks of Examples and Comparative Examples were weighed and collected in a glass petri dish having a diameter of 33 mm with a precision upper plate electronic balance capable of measuring up to 4 decimal places. Subsequently, it was stored in an ESPEC constant temperature and humidity chamber (ModelPL-3KP) having a temperature of 32 ± 0.5 ° C. and a humidity of 30 ± 5% at normal pressure. After 24 hours, each sample was taken out and its mass was measured. Next, the ink in the petri dish was scratched with a spatula so that the bottom of the petri dish could be seen, and the fluidity of the ink was confirmed.
A: The bottom of the petri dish is filled with ink within 5 seconds after scratching and becomes invisible.
B: After scratching, the bottom of the petri dish is filled with ink within 60 seconds and cannot be seen.
C: The bottom of the petri dish is visible even after 2 minutes or more after scratching.

<Ink storage stability>
Each ink was put in a polyethylene container, sealed, and stored at 70 ° C. for 2 weeks. The pigment particle diameter (D50) and viscosity were measured, and evaluated according to the rate of change from the initial physical properties as follows.
A: Change rate of both pigment particle size and viscosity is within 5% B: Change rate of both pigment particle size and viscosity is less than 10% C: Change rate of both pigment particle size and viscosity is 10% or more

<Ink foamability>
According to JIS K3622-1998, 8.5, the height of bubbles generated when 200 ml of the evaluation ink was dropped from a height of 900 mm on the water surface in 30 seconds at 25 ° C. was measured.
From the viewpoint of discharge stability, the bubble height needs to be 45 mm or less, and the bubble height is preferably 30 mm or less, more preferably 15 mm or less.

<Ink surface tension measurement>
The static surface tension of the ink for evaluation was measured at 25 ° C. using a fully automatic surface tension meter (CBVP-Z, manufactured by Kyowa Interface Science Co., Ltd.).

-Image formation process-
Using an ink jet recording apparatus (IPSiO GXe-5500, manufactured by Ricoh Co., Ltd.) under the environmental conditions adjusted to 23 ± 0.5 ° C. and 50 ± 5% RH, The drive voltage was varied so that the same amount of ink was applied to the recording medium. Next, the printing mode of the inkjet recording apparatus was set to “plain paper fast” and “glossy paper fast” to form an image.

<Abrasion resistance 1: Image peeling>
A 3 cm × 3 cm solid image chart was printed on the poster paper MAX manufactured by Sakurai Co., Ltd. having a basis weight of 180 g / m ^{2 in} the fast mode of glossy paper.
After drying, the printed part was rubbed 5 times with a cotton cloth, and the image peeling of the printed part was visually observed to evaluate the abrasion resistance. The results were determined according to the following criteria.
〔Evaluation criteria〕
A: No image peeling B: Slight peeling only at the edge of the image C: Image peeling

<Rubbing resistance 2: Dirt on non-printed area>
A 3 cm × 3 cm solid image chart was printed on the poster paper MAX manufactured by Sakurai Co., Ltd. having a basis weight of 180 g / m ^{2 in} the fast mode with glossy paper.
After drying, the printed part was rubbed 5 times with a cotton cloth, and the stain due to the extension / transfer of the image to the non-printed part was visually observed to evaluate the abrasion resistance. The results were determined according to the following criteria.
〔Evaluation criteria〕
A: No dirt B: Slightly dirty C: Dirt

<Discharge stability>
200 charts were continuously printed on My Paper (manufactured by Ricoh Co., Ltd.) to fill an area of 5% of A4 size paper per color created with Microsoft Word 2000 with a solid image, and evaluation was performed from ejection disturbance of each nozzle after launch. The printing mode used was a driver attached to the printer, in which the "plain paper-standard fast" mode was changed to "no color correction" from the user setting for plain paper.
〔Evaluation criteria〕
A: No discharge disturbance B: Some discharge disturbance C: Discharge disturbance or no discharge

<Image density measurement>
A color ink jet printer was filled with the prepared ink, and image evaluation was performed under the following conditions.
<Printing conditions>
Evaluation printer: IPSIO GX E5500 (Ricoh Co., Ltd.)
Evaluation paper: My Paper (Ricoh Co., Ltd.) (plain paper)
Chart: Black monochromatic solid patch Printing mode: Clean mode In the above chart, the density of a black solid image was measured with a reflection spectrodensitometer (Model: 939 manufactured by Xrite).

DESCRIPTION OF SYMBOLS 201 Conveyance roller 202 Platen roller 203 Recording medium 204 Pretreatment liquid application apparatus 205 Pretreatment liquid 206 Stirring / supply roller 207 Transfer / thinning roller 208 Application roller 209 Pressure adjustment apparatus 300 Inkjet image forming apparatus 301 Recording medium conveyance section 302 Pretreatment Process unit 303 Pre-processing post-drying unit 304 Image forming process unit 304K, 304C, 304M, 304Y Recording head 304K-1, 304K-2, 304K-3, 304K-4 Head unit 305 Post-processing process unit 306 Post-processing post-drying unit 307 Paper feeding device 308 Winding device 309 Nozzle surface of head unit 310 Print nozzle 311, 312, 313, 314 Heat roller 315 Pre-winding drying unit 401 Channel plate 402 Vibration plate 403 Nozzle plate 404 Nozzle 405 Zur communication passage 406 liquid chamber 408 common liquid chamber 409 an ink supply port 421 piezoelectric element 422 base substrate 423 struts 430 frame member 431 penetrating portion 432 the ink supply hole 451 piezoelectric material 452 internal electrodes 453 individual electrodes 454 common electrode

JP2013-155322A JP 2010-155359 A JP2011-74336 JP2008-19287

Claims (15)

An ink containing a colorant, an organic solvent, resin particles, an amine compound and water,
The resin particles are anionic urethane resins;
The amine compound is an organic amine compound having a boiling point of 120 ° C. or more and 200 ° C. or less and a molecular weight of 100 or less,
The content of the resin particles in the ink is 1% by mass or more,
When a 1 content (by weight) in the ink of the resin particles state, and are content 0.01 to 0.08 of the amine compound,
The particle diameter (D50) of the resin particles is 10 nm or more and 100 nm or less .
Ink characterized by that. The ink according to claim 1, wherein a content of the resin particles in the ink is 10% by mass or less .   The ink according to any one of claims 1 to 2, wherein a particle diameter (D50) of the resin particles is 10 nm or more and 50 nm or less.   The ink according to claim 1, wherein the resin particles are an anionic polycarbonate urethane resin or an anionic polyester urethane resin.   The ink according to any one of claims 1 to 4, wherein the organic solvent is 30 to 50 mass% of the whole ink.   The ink according to any one of claims 1 to 5, wherein the colorant is a self-dispersing colorant having a functional group.   The ink according to any one of claims 1 to 5, wherein the colorant is a resin-coated colorant.   The content of the resin particles is 0.05 or more and 2 or less, when the content (mass basis) of the colorant in the ink is 1. 8. Ink.   The ink according to claim 1, wherein the ink has a static surface tension at 25 ° C. of 20 mN / m or more and 27 mN / m or less. The ink according to any one of claims 1 to 9, wherein the ink further contains a fluorine-based surfactant and a compound represented by the following general formula (V).

[In Formula (V), R < ₁ > and R < ₂ > represents an alkyl group. ] The ink according to any one of claims 1 to 10, wherein the ink further contains a fluorine-based surfactant and a compound represented by the following general formula (VII).

[In formula (VII), R ₁₀ and R ₁₁ are independently alkyl groups having 3 to 6 carbon atoms, and R ₁₂ and R ₁₃ are independently alkyl groups having 1 to 2 carbon atoms. , N is an integer of 1-6. ]   The ink according to any one of claims 1 to 11, wherein the ink contains a fluorine-based surfactant, a surfactant other than a fluorine-based surfactant, and a foam suppressor.   It includes at least an ink flying step of applying an ink according to any one of claims 1 to 12 with at least one kind of stimulus selected from heat, pressure, and vibration and causing the ink to fly to record an image. An image forming method.   It has at least ink flying means for recording an image by applying the ink according to any one of claims 1 to 12 with at least one kind of stimulus selected from heat, pressure, and vibration, and causing the ink to fly. An image forming apparatus. An image formed product having the ink image according to any one of claims 1 to 12 on a recording medium, wherein the ink image contains a colorant, anionic urethane resin particles, and an amine compound, and the amine compound Is an organic amine compound having a boiling point of 120 ° C. or more and 200 ° C. or less and a molecular weight of 100 or less, and when the content (mass basis) of the resin particles is 1, the content of the amine compound is 0.01 or more and 0.00. An image formed product having a value of 08 or less.

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