JP6968335B2 - Ink ejection device and ink ejection method - Google Patents

Description

The present invention relates to an ink ejection device and an ink ejection method.

The inkjet recording method is a method of ejecting ink droplets and adhering them to a recording medium for recording. Since this method has a simple recording process, it is possible to increase the number of colors at low cost. Since it is non-contact printing, it is possible to perform overprinting, it is easy to improve the print quality, and it is possible to record at high speed without noise, so it is a home printer. Widely used from commercial printers to commercial printers.

As the water-based ink for inkjet recording, a water-based dye ink in which a dye is dissolved in an aqueous medium and a solvent-based ink in which an oil-soluble dye is dissolved in an organic solvent are used. Generally, from the viewpoint of environment and safety, water-soluble dyes dissolved in water or water and a water-soluble organic solvent are used in offices and homes. On the other hand, from the viewpoint of water resistance and color reproducibility of recorded images, water-based pigment inks in which pigments are made into fine particles and dispersed in water, and inks in which metallic pigments having high gloss are dispersed as industrial inks are attracting attention. ing.

However, when recording on glossy paper using pigment ink, the pigment, which is a coloring material, does not penetrate into the ink receiving layer and remains on the glossy paper surface to form a coating film. Therefore, the scratch resistance of the recording surface is inferior as compared with the case of recording on plain paper with pigment ink or the case of recording with dye ink penetrating into the ink receiving layer. In order to solve this problem, a means of adding urethane resin or acrylic resin to the ink to improve the abrasion resistance is taken.

However, in inks in which solids such as pigments and resin particles are dispersed, the sedimentation of the solids causes the ink to become non-uniform and uneven in concentration, and the solids that have settled and aggregated cause clogging of the nozzle. Discharge may become unstable.

On the other hand, Patent Document 1 is provided with a mechanism for circulating ink between an ink tank and an inkjet head by pressure control in order to maintain a state in which solids such as pigments are dispersed without precipitation. The device is disclosed.

In the circulation of ink by pressure control, there is a problem that a constant flow rate cannot be maintained when the water content in the ink evaporates and the viscosity increases, and the circulation tends to be insufficient.
The present invention uses an ink that contains a resin and has good abrasion resistance, but can suppress an increase in viscosity when water evaporates, so that the ink is always between the ink container and the ink ejection head at a substantially constant flow rate. It is an object of the present invention to provide an ink ejection device provided with a mechanism for circulating ink in the ink.

As a result of diligent studies by the present inventors, it is possible to suppress an increase in viscosity during water evaporation while ensuring abrasion resistance by using an ink in which urethane resin particles and a specific amine compound are used in combination. I found it possible.

That is, the present invention relates to the ink ejection device as described below.
An ink ejection device including an ink accommodating container for accommodating ink and an ejection head for ejecting ink supplied from the ink accommodating container, wherein the ejection head has an individual liquid chamber and the ink as an individual liquid. The ink ejection device includes an inflow path for flowing into the chamber, an outflow path for ejecting the ink from the individual liquid chamber, and a nozzle for ejecting the ink, and the ink ejection device receives the ink discharged from the outflow channel. A circulation means for circulating toward the inflow flow path is provided, and the ink contains a coloring material, an organic solvent, resin particles, an amine compound and water, and the resin particles are only anionic urethane resin. 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 0.08 or less , and the amine compound has a boiling point of 120 ° C. or more and 200 ° C. or less. An ink ejection device which is an organic amine compound having a molecular weight of 100 or less and in which the content of the amine compound in the ink is 0.01% by mass or more and 0.8% by mass or less.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to suppress an increase in ink viscosity at the time of water evaporation while having good scratch resistance including resin, and in a ejection device having an ink circulation function, ink is always circulated at a substantially constant flow rate. It is possible to make it.

FIG. 1 is a schematic side view showing an example of a mechanical unit of the ink ejection device of the present invention. FIG. 2 is an explanatory plan view of a main part of the ink ejection device of FIG. FIG. 3 is an external perspective view showing an example of an ink ejection head in the ink ejection device of the present invention. FIG. 4 is a cross-sectional explanatory view in a direction orthogonal to the nozzle arrangement direction of the ink ejection head of FIG. FIG. 5 is a partial cross-sectional explanatory view of the ink ejection head of FIG. 3 in a direction parallel to the nozzle arrangement direction. FIG. 6 is a plan view of the nozzle plate of the ink ejection head of FIG. FIG. 7A is a plan explanatory view of each member constituting the flow path member of the ink ejection head of FIG. FIG. 7B is a plan explanatory view of each member constituting the flow path member of the ink ejection head of FIG. FIG. 7C is a plan explanatory view of each member constituting the flow path member of the ink ejection head of FIG. FIG. 7D is a plan explanatory view of each member constituting the flow path member of the ink ejection head of FIG. FIG. 7E is a plan explanatory view of each member constituting the flow path member of the ink ejection head of FIG. FIG. 7F is a plan explanatory view of each member constituting the flow path member of the ink ejection head of FIG. FIG. 8A is a plan explanatory view of each member constituting the common liquid chamber member of the ink ejection head of FIG. FIG. 8B is a plan explanatory view of each member constituting the common liquid chamber member of the ink ejection head of FIG. FIG. 9 is a block diagram showing an example of the ink circulation system according to the present invention. FIG. 10 is a cross-sectional view taken along the line AA'of FIG. FIG. 11 is a cross-sectional view taken along the line BB'of FIG. FIG. 12 is a cross-sectional explanatory view showing an example of an ink ejection head in the ink ejection device of the present invention. FIG. 13 is a cross-sectional explanatory view of the ink ejection head of FIG.

(Ink ejection device and ink ejection method)
The ink ejection device of the present invention is an ink ejection device including an ink containing container for accommodating ink and an ejection head for ejecting ink supplied from the ink containing container.
The ink container contains an ink containing a coloring material, an organic solvent, resin particles, an amine compound, and water.
Then, the ink ejection head ejects an individual liquid chamber, an inflow flow path for flowing the ink into the individual liquid chamber, an outflow flow path for discharging the ink from the individual liquid chamber, and the ink. Has a nozzle.
Further, the ink ejection device of the present invention has a circulation means for circulating the ink from the outflow flow path toward the inflow flow path.
The ink is supplied between the ink container filled with the ink, the ink supply unit that supplies the ink to the individual liquid chamber via the inflow flow path, and the ink storage container and the ink supply unit. It is more preferable to have an outbound and inbound liquid feeding routes to be circulated.
The ink ejection method of the present invention (hereinafter, also referred to as “recording method”) can be suitably carried out by using the ink ejection device of the present invention.

In the ink ejection device of the present invention (hereinafter, also referred to as "recording apparatus"), in an ink ejection device provided with an ink circulation mechanism, it is said that a sufficient circulation flow rate cannot be secured due to an increase in viscosity when the water content of the ink evaporates. It is based on the knowledge. In particular, this problem is remarkable in an ink ejection device provided with an ink circulation mechanism by pressure control as an example.
This is because the ink ejection device of the present invention has a feature that the ink can suppress an increase in viscosity when water is evaporated in the process of circulating the ink from the inflow channel to the outflow channel through the individual liquid chamber. , A constant flow rate can be maintained by pressure control.
First, it contains a coloring material, an organic solvent, resin particles, an amine compound and water, which are inks used in the ink ejection device of the present invention, the resin particles are anionic urethane resin, and the amine compound has a boiling point of 120 ° C. or higher and 200 ° C. or higher. An ink which is an organic amine compound having a temperature of ℃ or less and a molecular weight of 100 or less will be described.

In the present invention, by using an anionic urethane resin for the resin particles contained in the ink, it is possible to improve the scratch resistance of the image when recorded on glossy paper and to achieve both good maintainability. This is because the polyurethane resin has excellent adhesion to the base material and has high abrasion resistance. Further, it is preferable to reduce the particle size of the resin particles. This makes it possible to form a coating film so as to fill the gap between the coloring material and the media, and between the coloring material and the coloring material, and it is possible to obtain higher abrasion resistance. Further, from the viewpoint of discharge stability and storage stability, it is preferable to use a polycarbonate-based urethane resin or a polyester-based urethane resin as the anionic urethane resin.

Further, in the present invention, by containing an amine compound having a boiling point of 120 or more and 200 ° C. or less and a molecular weight of 100 or less in the ink, it is possible to suppress an increase in viscosity at the time of water evaporation and enable circulation at a constant flow rate by pressure control. Therefore, it is possible to achieve both high discharge stability and maintainability. By reducing the molecular weight of the amine compound, substitution occurs as a counter ion of the water-dispersible resin, and by blending the amine compound having a boiling point higher than that of water in the ink, the resin particles are formed even when the water is evaporated. By preventing the evaporation of the counter ions and maintaining a stable dispersed state, the increase in the viscosity of the ink is suppressed. Further, when the content (mass standard) of the resin particles in the ink is 1, the content of the amine compound is preferably 0.01 or more and 1.00 or less, and if it is in this range, water evaporation by the amine compound. It is possible to secure storage stability while exerting the effect of suppressing an increase in ink viscosity at the time. This makes it possible to achieve both high scratch resistance, discharge stability, and maintainability.

Further, it is preferable that the static surface tension of the ink at 25 ° C. is 20 mN / m or more and 27 mN / m or less. More preferably, a fluorine-based surfactant, an acetylene glycol-based surfactant as represented by the formula (V) described later, and / or a defoaming agent represented by the formula (VII) described later. , Is preferably added. By adding these surfactants and defoaming agents, it is possible to achieve both high concentration and defoaming property of ink on plain paper.

Hereinafter, the ink, the ink ejection device, and the ink ejection method used in the present invention 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 improvement in scratch resistance of glossy paper and good maintainability.
Polyurethane resin is a reactive organism of polyisocyanate and polyol. One of the characteristics 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 base material and is excellent in wear resistance. Therefore, high glossy paper abrasion resistance can be expected by adding it to the ink.

The polyurethane resin particles are water-dispersible, and are particularly preferable to be used as an O / W type water dispersion. Further, such a dispersion includes an aqueous dispersion obtained by emulsifying a polyurethane resin using an emulsifier and a self-emulsifying type aqueous dispersion in which a functional group having an emulsifying action is introduced by copolymerization or the like.
Of these, a self-emulsifying anionic polycarbonate-based or polyester-based polyurethane resin aqueous dispersion is preferable because of its 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 size (D50) of the resin particles is related to the viscosity of the dispersion liquid, and if the composition is the same, the smaller the particle size, the higher the viscosity with the same solid content. In the present invention, the particle size (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, from the viewpoint of image abrasion resistance when recorded on glossy paper. By using resin particles having a particle size (D50) of 10 nm or more, thickening of the ink can be prevented and storage stability is also improved. Further, it is preferable to use resin particles having a particle size (D50) of 100 nm or less, and high scratch resistance that suppresses image elongation can be obtained. Further, it is more preferably 10 nm or more and 50 nm or less, and it is possible to form an image without peeling after rubbing.

Further, the resin particles have a function of fixing the coloring material on the paper surface, and it is preferable to form a film at room temperature to improve the fixing property of the coloring material. 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 viscosity of the resin film becomes strong and tack occurs on the printed matter. Therefore, the water-dispersible resin has a glass transition temperature of −30 ° C. or higher. Is preferable.
The content of the water-dispersible resin in the ink is preferably 1% by mass to 10% by mass, 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 it is 10% by mass or less, the increase in viscosity at the time of water evaporation is suppressed and good maintainability is maintained. Can be done.

Further, in the present invention, when the content (mass standard) of the coloring material 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 when the content of the coloring material (based on mass) is 0.05 or more, and good ejection stability can be ensured when the content is 2 or less.

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

-Amine compound-
The present invention 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 90 ° C. or lower. Further, when the content (mass standard) of the resin particles in the ink is 1, the content of the amine compound is preferably 0.01 or more and 1.00 or less, and more preferably 0.01 or more and 0.08 or less. .. Good maintainability is realized by being within the above range.

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

As the amine compound, a compound represented by the following formula (I) or formula (II) is preferable.

［式（Ｉ）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、ヒドロ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。］

[In the formula (I), 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, this does not apply when all are hydrogen atoms. ]

［式（II）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。］

[In formula (II), R ₄ , R ₅ , and R ₆ represent a hydrogen atom, a methyl group, an ethyl group, a hydroxymethyl group, and an alkyl group of 1 to 4. ]

Examples of the compound represented by the formula (I) and the formula (II) include 1-amino-2-propanol, 3-amino-1-propanol, N-methylethanolamine, N, N-dimethylethanolamine, 1 -Amino-2-methyl-propanol and the like can be mentioned.
The content of the amine compound in the ink is not particularly limited, but is preferably 0.01% by mass to 5% by mass, particularly preferably 0.05% by mass to 2% by mass, from the viewpoint of adjusting the pH of the ink. Further, the amine compound contained in the ink can be used in combination with another amine compound in addition to the amine compound.

-Organic solvent-
For the ink of the present invention, it is preferable to use a polyhydric alcohol having a solubility parameter (SP value) in the range of 11.8 to 14.0 as the organic solvent. Examples of the polyhydric alcohol having a 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: 11.95) SP value: 11.80), triethylene glycol (SP value: 12.12), diethylene glycol (SP value: 13.02) can be mentioned. Particularly preferred are 3-methyl-1,3-butanediol (SP value: 12.05), 1,2-butanediol (SP value: 12.75), and 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) is preferable.

Further, in addition to the above-mentioned polyhydric alcohol, other wetting agents can be used in combination with the ink of the present invention. The ratio of the amount of the polyhydric alcohol to the other wetting agent (mass ratio) depends not a little on the type and amount of other additives, so it cannot be said unconditionally, but for example, in the range of 10/90 to 90/10. It is preferably present, and more preferably 40/60 to 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, and the like. Other wetting agents and the like can be mentioned.

Examples of the polyhydric alcohols include dipropylene glycol (bp232 ° C.), 1,5-pentanediol (bp242 ° C.), 3-methyl-1,3-butanediol (bp203 ° C.), and propylene glycol (bp187 ° C.). , 2-Methyl-2,4-pentanediol (bp197 ° C), ethylene glycol (bp196-198 ° C), tripropylene glycol (bp267 ° C), hexylene glycol (bp197 ° C), polyethylene glycol (viscous liquid to solid) , Polyethylene glycol (bp187 ° C), 1,6-hexanediol (bp253-260 ° C), 1,2,6-hexanetriol (bp178 ° C), trimethylolethane (solid, mp199-201 ° C), trimethylolpropane (solid, mp199-201 ° C) Solid, mp61 ° C.) and the like.

Examples of the polyhydric alcohol alkyl ethers include ethylene glycol monoethyl ether (bp135 ° C.), ethylene glycol monobutyl ether (bp171 ° C.), diethylene glycol monomethyl ether (bp194 ° C.), diethylene glycol monobutyl ether (bp231 ° C.), and ethylene glycol mono. -2-Ethylhexyl ether (bp229 ° C.), propylene glycol monoethyl ether (bp132 ° C.), and the like can be mentioned.

Examples of the polyhydric alcohol aryl ethers include ethylene glycol monophenyl ether (bp237 ° C.) and ethylene glycol monobenzyl ether.

Examples of the nitrogen-containing heterocyclic compound include N-methyl-2-pyrrolidone (bp202 ° C.), 1,3-dimethyl-2-imidazolidinone (bp226 ° C.), ε-caprolactam (bp270 ° C.), and γ-butyrolactone. (Bp204 to 205 ° C.) and the like.

Examples of the amides include formamide (bp210 ° C.), N-methylformamide (bp199 to 201 ° C.), N, N-dimethylformamide (bp153 ° C.), N, N-diethylformamide (bp176 to 177 ° C.) and the like. Can be mentioned.

Examples of the amines include monoethanolamine (bp170 ° C.), diethanolamine (bp268 ° C.), triethanolamine (bp360 ° C.), N, N-dimethylmonoethanolamine (bp139 ° C.), and N-methyldiethanolamine (bp243 ° C.). ), N-Methylethanolamine (bp159 ° C.), N-phenylethanolamine (bp282-287 ° C.), 3-aminopropyldiethylamine (bp169 ° 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 range of 11.8 to 14.0 in the ink and the organic solvent of the wetting agent shall be 30 to 50% by mass of the entire ink. Is preferable.
If the content is less than 30% by mass, the viscosity at the time of evaporation of water increases remarkably, and if it exceeds 50% by mass, the drying property may become severe.

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

［式（III）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。］

[In formula (III), R ₇ is a methyl group or an ethyl group, R ₈ is a hydrogen or a methyl group, and R ₉ is an ethyl group or a propyl group. ]

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

-Color material-
Next, the coloring material used in the present invention will be described.
As the coloring material, 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 coloring material is preferably 2 to 15% by mass, more preferably 3 to 12% by mass, based on the solid content of the entire ink. If the content is less than 2% by mass, the color development property and the image density of the ink may be lowered, and if it exceeds 15% by mass, the ink may be thickened and the ejection property may be deteriorated, which is preferable. No. The pigment is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include inorganic pigments and organic pigments for black or color.

Particularly preferable forms of the water-dispersible coloring material when the coloring material is a pigment include the following first and second forms.
(1) First form: The coloring material contains an aqueous dispersion of polymer fine particles containing a water-insoluble or sparingly water-soluble pigment.
(2) Second form: The coloring material has at least one hydrophilic group on the surface and exhibits water dispersibility in the absence of a dispersant (hereinafter, may be referred to as "self-dispersible pigment"). ) Is contained.

As the water-dispersible coloring material of the first form, it is preferable to use a polymer emulsion in which polymer fine particles contain a pigment in addition to the above pigment.
The polymer emulsion in which the polymer fine particles contain a pigment is one in which the pigment is encapsulated in the polymer fine particles, or one in which the pigment is adsorbed on the surface of the polymer fine particles.

In the present invention, it is preferable to use a self-dispersible pigment or a resin-coated pigment as the water-dispersible coloring material. 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 color material can be stably dispersed without using a dispersant by coating the pigment with a resin having a hydrophilic group and microencapsulating it.
The content of the pigment derived from the coloring material in the ink is preferably 3.0% by mass or more and 10.0% by mass or less. If the pigment content is less than 3.0% by mass, the image density may decrease, and if 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, Arabic rubber, dextran, casein, protein, natural rubber, and carboxy. Polymers or copolymers of polymethylene, polyvinyl alcohol, polyvinylpyrrolidone, polyvinylacetate, polyvinyl chloride, polyvinylidene chloride, cellulose, ethylcellulose, methylcellulose, nitrocellulose, hydroxyethylcellulose, cellulose acetate, polyethylene, polystyrene, (meth) acrylic acid. Polymers, polymers or copolymers of (meth) acrylic acid esters, (meth) acrylic acid- (meth) acrylic acid ester copolymers, styrene- (meth) acrylic acid copolymers, styrene-maleic acid copolymers Examples thereof include coalescing, sodium alginate, fatty acids, paraffins, beeswax, water brazing, hardened beef fat, 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. Examples of the nonionic organic polymer material include polyvinyl alcohol, polyethylene glycol monomethacrylate, polypropylene glycol monomethacrylate, methoxypolyethylene glycol monomethacrylate or a (co) polymer thereof), and a cationic ring-opening polymer of 2-oxazoline. And so on. In particular, a completely saponified product of polyvinyl alcohol is particularly preferable because it has a low water solubility and has a property of being easily dissolved in hot water but difficult to be dissolved in cold water.

Further, the content of the organic polymer material constituting the wall film material of the microcapsules of the resin-coated color material is preferably 15% by mass or more and 40% by mass or less. By setting the amount of the organic polymer material in the above range, the content of the organic polymer material in the capsule is relatively low, and therefore the color development property of the pigment due to the organic polymer material covering the pigment surface. It is possible to suppress the decrease in the amount. If the amount of the organic polymer material is less than 15% by mass, it becomes difficult to exert the effect of encapsulation, and conversely, if it exceeds 40% by mass, the color development property of the pigment is significantly deteriorated.

As the pigment, carbon black or a color pigment is used.
The carbon black is a carbon black produced by the furnace method or the channel method, has a primary particle size of 15 to 40 millimicrons, a specific surface area of 50 to 300 m ² / g by the BET method, and a DBP oil absorption of 40. Those having ~ 150 ml / 100 g, a volatile content of 0.5 to 10%, and a pH value of 2 to 9 are preferable. 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 (above, Mitsubishi Chemical), Raven700, 5750, 5250, 5000, 3500, 1255 (above, made in Colombia), Regal400R, 330R, 660R, MogulL, Monarch700, 800, 880, 900, 1000, 1100, 1300, Monarch 1400 (Above, made 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) , Etc., but are not limited to these.

The color pigments include anthraquinone, phthalocyanine blue, phthalocyanine green, diazo, monoazo, pyranthron, 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 (Perinon Red), Pigment Red 216 (Brominated Pirantron Red) and Pigment Red 226 (Pyrantron Red). Typical examples of Pyrellin are Pigment Red 123 (Belmilion), Pigment Red 149 (Scarlet), Pigment Red 179 (Maroon), Pigment Red 190 (Red), Pigment Baolet, Pigment Red 189 (Yellow Shade Red) and Pigment. Includes Red 224. Representative examples of thioindigoid include Pigment Red 86, Pigment Red 87, Pigment Red 88, Pigment Red 181 and 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 color pigments are described in The Color Index, 3rd Edition (The Society of Dyers and Colorists, 1982).
Furthermore, if an organic pigment that is a self-dispersing pigment or a self-dispersing carbon black is used as the coloring material, the dispersibility of the pigment is improved even if the content of the organic polymer in the capsule is relatively low. In addition, it is more preferable for the present invention because it is possible to secure sufficient storage stability of the ink.

The average particle size of the pigment is not particularly limited and may be appropriately selected depending on the intended purpose, preferably 10 nm to 150 nm, more preferably 20 nm to 100 nm, still more preferably 30 nm to 80 nm. If the average particle size exceeds 150 nm, not only the saturation of the printed image is lowered, but also thickening aggregation during ink storage and nozzle clogging during printing may easily 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.

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

It is preferable to use a pigment as the resin-coated color material used in the present invention, but dyes can also be used for the resin-coated color material described above, and an example of this water-soluble dye is shown below. It is preferable to use one having excellent water resistance and light resistance. Specific examples of these dyes include acid dyes and edible 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; C.I. I. Acid Blue 9,29,45,92,249; C.I. I. Acid Black 1,2,7,24,26,94; C.I. I. Food Yellow 3,4; C.I. I. Food Red 7, 9, 14; C.I. I. Food blacks 1 and 2 are examples.

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

Examples of the basic dye 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; C.I. 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; C.I. I. Basic black 2, 8 and the like can be mentioned.

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

As a method of coating a water-insoluble pigment with an organic polymer material and microencapsulating it, all conventionally known methods can be used, and a chemical manufacturing method, a physical manufacturing method, a physicochemical method, and a mechanical method can be used. Examples thereof include an interfacial polymerization method, an in-situ polymerization method, an in-liquid curing coating method, a core selvation (phase separation) method, an in-liquid drying method, a melt dispersion cooling method, and an air suspension. Examples include a coating method, a spray drying method, an acid analysis method, and a phase inversion emulsification method.

Here, the microencapsulation will be briefly described. The above-mentioned interfacial polymerization method is a method in which two kinds of monomers or two kinds 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 gas monomer and a catalyst, or two reactive substances are supplied from either one of the continuous phase nuclei particles side to cause a reaction to form a wall film. The in-liquid curing coating method is a method of insolubilizing drops of a polymer solution containing core material particles in a liquid with a curing agent or the like to form a wall film, and the core selvation (phase separation) method is a method. This is a method of separating a polymer dispersion liquid in which core material particles are dispersed into a core selvate (concentrated phase) having a high polymer concentration and a dilute phase to form a wall film. The in-liquid drying method is a method of forming a core material. By preparing a liquid dispersed in a solution of wall membrane material, and putting the dispersion liquid in a liquid in which the continuous phase of this dispersion is immiscible, a composite emulsion is formed, and the medium in which the wall membrane material is dissolved is gradually removed. It is a method of forming a wall film, and the melt dispersion cooling method utilizes a wall film material that melts into a liquid when heated and solidifies at room temperature, heats and liquefies this material, and disperses core material particles in it. It is a method of forming a wall film by turning it into fine particles and cooling it to form a wall film. It is a method of spray-mixing a coating liquid of a wall film substance to form a wall film. In the spray drying method, the encapsulating stock solution is sprayed and brought into contact with hot air to evaporate and dry the volatile components to form the wall film. The acid analysis method imparts solubility in water by neutralizing at least a part of the anionic groups of the organic polymer compounds containing anionic groups with a basic compound, and is a coloring material. In this method, the mixture is kneaded in an aqueous medium, neutralized or acidified with an acidic compound, and the organic compounds are precipitated and fixed to the coloring material, and then neutralized and dispersed. The phase inversion emulsification method is based on water. This is a method in which a mixture containing an anionic organic polymer having a dispersibility and a coloring material is used as an organic solvent phase, and water is added to the organic solvent phase, or water is added to the organic solvent phase. ..

It is preferable to select an organic polymer suitable for the microencapsulation method. For example, in the case of the interfacial polymerization method, polyester, polyamide, polyurethane, polyvinylpyrrolidone, epoxy resin and the like are suitable. In the case of 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, etc. are suitable. In the case of the submerged curing method, sodium alginate, polyvinyl alcohol, gelatin, albumin, epoxy resin and the like are suitable. In the case of the core selvation method, gelatin, celluloses, casein and the like are suitable. Further, in order to obtain a fine and uniform microencapsulating pigment, of course, all conventionally known encapsulation methods can be used in addition to the above.

When the phase inversion method or the acid analysis method is selected as the method of microencapsulation, anionic organic polymers are used as the organic polymers constituting the wall film material of the microcapsules.
The phase inversion method is a method of using an anionic organic polymer having a self-dispersing ability or a dissolving ability in water and a composite or a composite with carbon black, or a 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). The carbon black here includes self-dispersive carbon black. In the above phase inversion method, there is no problem even if the organic solvent phase is mixed with a vehicle for a recording liquid or an additive to produce the product. In particular, from the viewpoint that a dispersion liquid for a recording liquid can be directly produced, it is more preferable to mix the liquid medium of the recording liquid.

On the other hand, the acid analysis method is a step of neutralizing a part or all of the anionic groups of anionic group-containing organic polymers with a basic compound and kneading them with a coloring material such as carbon black in an aqueous medium and acidity. A hydrous cake obtained by a production method consisting of a step of precipitating anionic group-containing organic polymers by neutralizing or acidifying the pH with a compound and adhering to the pigment is obtained by using a basic compound as one of the anionic groups. It is a method of microencapsulating by neutralizing a part or all. By doing so, it is possible to produce an aqueous dispersion containing an anionic microencapsulating pigment that is fine and contains a large amount of pigment.

Solvents used for microencapsulation include, for example, 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 the microcapsules are stirred and redispersed together with water and a necessary solvent to be used in the present invention. Obtain a recording solution that can be used. The average particle size of the encapsulating pigment obtained by the above method is preferably 50 nm to 180 nm.

In the self-dispersion type pigment, at least one kind of hydrophilic group is bonded directly to the surface of the pigment or through other atomic groups, and the pigment can be stably dispersed without using a dispersant. As the pigment having a hydrophilic group introduced into the surface used in the present invention, an ionic pigment is preferable, and an anionic or cationically charged pigment is preferable.

Examples of the anionic hydrophilic group include -COOM, -SO ₃ M, -PO ₃ HM, -PO ₃ M ₂ , -SO ₂ NH ₂ , and -SO ₂ NHCOR (where M in the formula is a hydrogen atom, It represents an alkali metal, ammonium or organic ammonium, and 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) and the like. Be done. In the present invention, especially -COOM, it is preferable to use a -SO ₃ M is bonded to the pigment surface among these.
Examples of the method for obtaining an anionically charged pigment include a method of oxidizing the pigment with sodium hypochlorite, a method of sulfonate treatment, and a method of reacting with a diazonium salt, but the present invention is limited thereto. Not that.

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

The content of the water-dispersible color material in the ink is preferably 1 to 15% by mass, more preferably 2 to 10% by mass in terms of solid content. If the content is less than 1% by mass, the color development property and the image density of the ink may be lowered, and if it exceeds 15% by mass, the ink may be thickened and the ejection property may be deteriorated. Yes, and it is also economically unfavorable.

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

As the dispersant, a polymer dispersant, a surfactant, or the like can be used, and there is no particular limitation, but from the viewpoint of pigment dispersion stability during storage, an alkali metal salt of a naphthalene sulfonic acid formalin condensate and an alkali metal salt. / Or it is preferably one containing an organic base salt as a main component.

A water-soluble resin can be used as the polymer dispersant. Specific examples of the water-soluble resin include styrene, styrene derivative, vinylnaphthalene derivative, aliphatic alcohol ester of α, β-ethylenic unsaturated carboxylic acid, acrylic acid, acrylic acid derivative, maleic acid, maleic acid derivative, and itacone. Examples thereof include block copolymers composed of at least two or more monomers selected from acids, itaconic acid derivatives, fumaric acid, fumaric acid derivatives, random copolymers, salts thereof and the like. These water-soluble resins are alkali-soluble resins that are soluble in an aqueous solution in which a base is dissolved, and among these, those having a weight average molecular weight of 3000 to 20000 have a low viscosity of the dispersion liquid when used in ink. It is particularly preferable because it has the advantages that it can be converted and easily dispersed.

Further, the surfactant can be appropriately selected and used according to the pigment type or the ink formulation, and is generally classified into nonionic, anionic and amphoteric.
Examples of the nonionic surfactant include polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene myristyl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, and polyoxyethylene oleyl ether, and polyoxyethylene octylphenyl. Polyoxyethylene alkyl phenyl ether such as ether, polyoxyethylene nonylphenyl ether, polyoxyethylene-α-naphthyl ether, polyoxyethylene-β-naphthyl ether, polyoxyethylene monostyrylphenyl ether, polyoxyethylene distyrylphenyl ether , Polyoxyethylene alkyl naphthyl ether, polyoxyethylene monostylyl naphthyl ether, polyoxyethylene distyryl naphthyl ether, and the like. Further, it has a surfactant such as a polyoxyethylene polyoxypropylene block copolymer in which a part of polyoxyethylene of these surfactants is replaced with polyoxypropylene, and an aromatic ring such as polyoxyethylene alkyl phenyl ether. A surfactant obtained by condensing the compound with formalin or the like can also be used.

The HLB of the nonionic surfactant is preferably 12 to 19.5, more preferably 13 to 19. If the HLB is less than 12, the surfactant does not easily adapt to the dispersion medium and the dispersion stability tends to deteriorate. If the HLB exceeds 19.5, the surfactant is less likely to be adsorbed on the pigment, so that the dispersion stability also tends to deteriorate. Sex tends to worsen.

Examples of the anionic surfactant include polyoxyethylene alkyl ether sulfate, polyoxyethylene alkylphenyl ether sulfate, polyoxyethylene monostyrylphenyl ether sulfate, polyoxyethylene distyrylphenyl ether sulfate, and polyoxyethylene alkyl ether. Phosphate, polyoxyethylene alkylphenyl ether phosphate, polyoxyethylene monostyrylphenyl ether phosphate, polyoxyethylene distyrylphenyl ether phosphate, polyoxyethylene alkyl ether carboxylate, polyoxyethylene alkylphenyl Ether carboxylate, polyoxyethylene monostyrylphenyl ether carboxylate, polyoxyethylene distyrylphenyl ether carboxylate, naphthalene sulfonate formalin condensate, melanin sulfonate formalin condensate, dialkyl sulfosuccinate salt, sulfosuccinate Acid alkyl disalt, polyoxyethylene alkyl sulfosuccinic disalt, alkyl sulfoacetate, α-olefin sulfonate, alkylbenzene sulfonate, alkylnaphthalene sulfonate, alkyl sulfonate, N-acyl amino acid salt, acylation Examples include peptides and soaps.

-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 ink droplets permeate into the recording medium after landing on the recording medium such as paper, so that feathering and color bleeding are reduced. Can be done.

Surfactants are classified into nonionic, anionic and amphoteric depending on the polarity of the hydrophilic group.
Further, it is classified into fluorine-based, silicone-based, acetylene-based and the like 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 and an acetylene-based surfactant may be used in combination.
More preferably, a combination of a fluorine-based surfactant and an acetylene glucol-based surfactant is preferable. The addition of a surfactant deteriorates the defoaming property of bubbles, but by using these surfactants in combination, the influence of the bubble property is relatively small, and the surface tension can be lowered.
When the surfactant is added to the ink as a penetrant, the amount added is preferably 0.05 to 5% by mass, more preferably 0.1 to 3% by mass.

Examples of the fluorine-based surfactant include perfluoroalkyl sulfonates, perfluoroalkyl carboxylates, perfluoroalkyl phosphates, perfluoroalkyl ethylene oxide adducts, perfluoroalkyl betaines, and perfluoroalkylamine oxide compounds. Can be mentioned.
Generally, commercially available fluorine-based compounds include, for example, Surflon S-111, S-112, S-113, S121, S131, S132, S-141, S-144, S-145 (manufactured by Asahi Glass Co., Ltd.). , Fluorad 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), Zonir FS-300, FSN, FSN-100, FSO, FSO-100 (manufactured by DuPont), Ftop EF-351, 352, 801 and 802 (manufactured by Gemco), FT-250, 251 (manufactured by Neos), PF-151N, PF-136A, PF-156A (manufactured by OMNOVA) and the like can be mentioned.
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.

Examples of the nonionic surfactant include polyols, glycol ethers, polyoxyethylene alkyl ethers, polyoxyethylene polyoxypropylene alkyl ethers, polyoxyethylene alkyl esters, polyoxyethylene sorbitan fatty acid esters, and polyoxyethylene alkyl phenyl ethers. Examples thereof include polyoxyethylene alkylamine, polyoxyethylene alkylamide, and acetylene glycol. Examples of the anionic surfactant include polyoxyethylene alkyl ether acetate, dodecylbenzene sulfonate, lauryl salt, polyoxyethylene alkyl ether sulfate salt and the like.

Examples of the silicone-based surfactant include polyether-modified silicone compounds. The polyether-modified silicone compound is a side chain type (pendant type) in which a polyether group is introduced into the side chain of polysiloxy acid, a one-ended type in which a polyether group is introduced in one end of a polysiloxane, and a double-ended type in which a polyether group is introduced at both ends. (ABA type), side chain double-ended type in which polyether groups are introduced into both the side chain and both ends of the polysiloxane, polysiloxane (A) having a polyether group introduced and polysiloxane (B) not introduced are 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 not particularly limited in the present invention, it is preferably a side chain type (pendant type) having a structure in which a polyether group is introduced into the side chain of polysiloxane.
As commercially available products, for example, KF-351A, KF-352A, KF-353, KF-354L, KF-355A, KF-615A, KF-945, KF-618, KF-6011, KF-6015 , KF-6004 (manufactured by Shin-Etsu Chemical Co., Ltd.), SF-3771, SF-8427, SF-8428, SH-3479, 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 can be mentioned.

［式（IV）式中、ｍ又はｎは、１以上の整数を表す。］

［式（Ｖ）式中、Ｒ₁及びＲ₂は、アルキル基を表す。］

Examples of the acetylene-based surfactant include an acetylene glycol-based surfactant or an acetylene alcohol-based surfactant, and a compound represented by the following general formula (IV) or the following general formula (V) is preferable. Specific examples thereof include compounds represented by the following formula (VI). The combined use of the fluorine-based surfactant and the acetylene glycol-based surfactant represented by the formula (V) is more preferable. When the fluorine-based surfactant and the surfactant represented by the formula (V) are used in combination, the interface represented by the general formula (V) when the fluorine-based surfactant is set to 1 on a mass basis. The activator is preferably 1.50 or less.

[In equation (IV), m or n represents an integer of 1 or more. ]

[In the formula (V), R ₁ and R ₂ represent an alkyl group. ]

Commercially available products can be used as the acetylene glycol-based surfactant or the acetylene alcohol-based surfactant, and the commercially available products include, for example, Dynol 604 and Dynol 607 (manufactured by Air Products &Chemicals); Surfy. Noll 104, Surfinol 420, Surfinol 440, Surfinol SE (manufactured by Nissin Chemical Industry Co., Ltd.); Orfin E1004, Orfin E1010, Orfin EXP.4001, Orfin EXP.4200, Orfin EXP.4051F, Orfin EXP.4123 ( (Manufactured by Nissin Chemical Industry Co., Ltd.) and the like.

-Other ingredients-
The other components are not particularly limited and may be appropriately selected as needed. For example, a pH adjuster, a defoaming agent (antifoaming agent), an antiseptic / antifungal agent, a chelating reagent, a rust preventive agent, and an oxidation agent. Examples include inhibitors, UV absorbers, oxygen absorbers, light stabilizers, and the like.

<Antifoaming agent>
In the present embodiment, the defoaming agent is used to suppress foaming by adding a small amount to the ink. Here, foaming means that the liquid forms a thin film and wraps the air. Properties such as surface tension and viscosity of the ink are involved in the formation of this bubble. That is, a liquid having a high surface tension such as water is difficult to foam because a force is exerted to reduce the surface area of the liquid as much as possible. On the other hand, the high-viscosity and high-permeability ink tends to foam due to its low surface tension, and the foam generated by the viscosity of the solution is easily maintained and difficult to defoam.

Usually, the defoaming agent destroys the foam by locally lowering the surface tension of the foam film to destroy the foam, or by interspersing the foaming liquid insoluble defoaming agent on the surface of the foaming liquid. When a fluorine-based surfactant having an extremely strong function of lowering the surface tension is used as a surfactant in the ink, the surface tension of the foam film is locally lowered even if a defoaming agent by the former mechanism is used. It is not usually used because it cannot be used. Therefore, a defoaming agent insoluble in the latter foaming liquid is used, but in this case, the stability of the ink is lowered by the defoaming agent insoluble in the solution.

On the other hand, the defoaming agent of the following general formula (VII) has a high compatibility with the fluorine-based surfactant, although the function of lowering the surface tension is not as strong as that of the fluorine-based surfactant. Therefore, the foam suppressant is efficiently incorporated into the foam film, and the surface of the foam film becomes locally unbalanced due to the difference in surface tension between the fluorine-based surfactant and the foam suppressant, and the foam is destroyed. Conceivable.

In the present embodiment, the compound represented by the following general formula (VII) is preferable as the defoaming agent. The content (mass basis) of the compound represented by the general formula (VII) is preferably 1.00 or less when the fluorine-based 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 alkyl groups independently having 3 to 6 carbon atoms, and R ₁₂ and R ₁₃ are alkyl groups independently having 1 to 2 carbon atoms. , N is an integer of 1 to 6. ]

Preferred examples of the compound represented by the general formula (VII) are 2,4,7,9-tetramethyldecane-4,7-diol, 2,5,8,11-tetramethyldodecane-5,8. -Dodecane can be mentioned. Particularly preferable is 2,4,7,9-tetramethyldecane-4,7-diol, which is effective not only in the effect of foam-suppressing property but also in the improvement of wettability, and is effective in improving foaming property and wettability. It is desirable to add it in order to achieve both.

The content of the defoaming agent in the ink is preferably 0.01 to 10% by mass, more preferably 0.1 to 5% by mass. If the content of the defoaming agent is less than 0.01% by mass, the effect of suppressing foam may not be obtained, and if it exceeds 10% by mass, the defoaming effect reaches a plateau and the viscosity. The physical properties of the ink 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 blended ink, and can be appropriately selected depending on the intended purpose. For example, alcohol amine. Examples include hydroxides of alkali metal elements, 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 melted out is large, which may cause problems such as deterioration, leakage, and ejection failure of the ink.

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

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

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

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

Examples of the antiseptic and 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 ethylenediamine tetraacetate, sodium nitrilo triacetate, sodium hydroxyethylethylenediamine triacetate, sodium diethylenetriamine pentaacetate, sodium uramil diacetate and the like.

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

Examples of the antioxidant include a phenol-based antioxidant (including a hindered phenol-based antioxidant), an amine-based antioxidant, a sulfur-based antioxidant, a phosphorus-based antioxidant, and the like.

Examples of the phenol-based antioxidant (including a hindered phenol-based antioxidant) include butylated hydroxyanisole, 2,6-di-tert-butyl-4-ethylphenol and 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-dihydrokiphenyl) propionate] methane, 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, etc. Can be mentioned.

Examples of the sulfur-based antioxidant include dilauryl 3,3'-thiodipropionate, distearylthiodipropionate, laurylstearylthiodipropionate, dimyristyl 3,3'-thiodipropionate, and distearyl β. , β'-thiodipropionate, 2-mercaptobenzimidazole, dilaurylsulfide and the like.

Examples of the phosphorus-based antioxidant include triphenylphosphine, octadecylphosphite, triisodecylphosphite, trilauryltrithiophosphite, trinonylphenylphosphine and the like.

Examples of the ultraviolet absorber include benzophenone-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, salicylate-based ultraviolet absorbers, cyanoacrylate-based ultraviolet absorbers, nickel complex salt-based ultraviolet absorbers, and the like.

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, etc. may be mentioned.

Examples of the benzotriazole-based ultraviolet absorber include 2- (2'-hydroxy-5'-tert-octylphenyl) benzotriazole, 2- (2'-hydroxy-5'-methylphenyl) benzotriazole, 2-. Examples thereof include (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 phenylsalicylate, p-tert-butylphenylsalicylate, p-octylphenylsalicylate, and the like.
Examples of the cyanoacrylate-based ultraviolet absorber include ethyl-2-cyano-3,3'-diphenyl acrylate, methyl-2-cyano-3-methyl-3- (p-methoxyphenyl) acrylate, and butyl-2-. Examples thereof include cyano-3-methyl-3- (p-methoxyphenyl) acrylate.

Examples of the nickel complex salt-based ultraviolet absorber include nickel bis (octylphenyl) sulfate, 2,2'-thiobis (4-tert-octylferate) -n-butylamine nickel (II), 2,2'-thiobis. Examples thereof include (4-tert-octylferate) -2-ethylhexylamine nickel (II), 2,2'-thiobis (4-tert-octylferate) triethanolamine nickel (II), and the like.

-Ink manufacturing method-
The ink of the present invention disperses or dissolves a water-dispersible coloring material, an organic solvent, a water-dispersible resin, a surfactant, a penetrant and water, and if necessary, other components in an aqueous medium, and further needs to be obtained. It is manufactured by stirring and mixing accordingly. This stirring and mixing can be performed by, for example, a sand mill, a homogenizer, a ball mill, a paint shaker, an ultrasonic disperser, etc., and the stirring and mixing is performed by a stirrer using ordinary stirring blades, a magnetic stirrer, a high-speed disperser, or the like. be able to.

-Ink physical characteristics-
The physical characteristics 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. When the ink viscosity is 5 mPa · s or more, the effect of improving the print density and the character quality can be obtained. On the other hand, by suppressing the ink viscosity to 25 mPa · s or less, the ejection property can be ensured.
Here, the viscosity can be measured at 25 ° C. using, for example, a viscometer (RE-550L, manufactured by Toki Sangyo Co., Ltd.).

The ink viscosity increase rate when 30% water evaporation of the ink is preferably 400% or less. When the ink viscosity increase rate is within this range, fluidity can be ensured even during water evaporation, and a sufficient ink circulation flow rate can be obtained.

The static surface tension of the ink is preferably 20 to 35 mN / m, more preferably 20 to 27 mN / m at 25 ° C. By setting the static surface tension to 35 mN / m or less, the ink can be wetted and spread on the paper, and a high image density can be obtained.
Further, when the dynamic surface tension is 25 ° C., the dynamic surface tension at a surface life of 15 ms by the maximum foam pressure method is preferably 35 mN / m or less, more preferably 33 mN / m or less. By setting the dynamic surface tension at a surface life of 15 ms to 35 mN / m or less, the wettability and permeability of general-purpose printing paper are improved, and the effect of reducing beading and color bleeding is also enhanced. In addition, the color development and white spots of plain paper are also improved. The ink may be stored in a container such as an ink cartridge and used.

The ink of the present invention uses a piezoelectric element as an inkjet head as a pressure generating means for pressurizing the ink in the ink flow path to deform a vibrating plate forming the wall surface of the ink flow path to change the volume inside the ink flow path. A so-called piezo type that ejects ink droplets (see Japanese Patent Publication No. 2-51734), or a so-called thermal type that heats ink in the ink flow path using a heat generating resistor to generate bubbles (see Japanese Patent Publication No. 2-51734). (Refer to Japanese Patent Publication No. 61-59911), the ink is formed by arranging the vibrating plate forming the wall surface of the ink flow path and the electrode facing each other and deforming the vibrating plate by the electrostatic force generated between the vibrating plate and the electrode. It can be satisfactorily used for a printer equipped with any inkjet head, such as an electrostatic type that changes the volume in the flow path to eject ink droplets (see JP-A-6-71882).

<< Ink ejection head >>
The ink ejection head causes the ink to flow into the individual liquid chamber from the inflow flow path, flows out from the individual liquid chamber to the outflow flow path, and causes the ink to flow.
Further, the ink ejection head is connected to an ink supply unit that supplies the ink to the individual liquid chamber via the inflow flow path. When the ink ejection device has the circulation means, the ink can be circulated between the ink ejection head and the ink supply unit by connecting the outflow flow path to the ink supply unit. preferable. This is advantageous in that the amount of waste ink due to the outflow from the outflow channel can be reduced.

<< Circulation means >>
The circulation means is a means for circulating the ink from the inflow channel to the outflow channel. It is preferable that the circulation means circulates the ink before the ink ejection head ejects the ink.
The ink ejection head may also eject the ink after the circulation means circulates the ink and then stops the circulation, and the circulation means always circulates the ink while ejecting the ink. You can also.
The circulation means is not particularly limited and may be appropriately selected depending on the intended purpose.

<< Ink container >>
The ink is stored in the ink container (hereinafter, also referred to as an "ink cartridge", "cartridge", or "main tank"), and the ink is supplied via the liquid feeding path of the outward path and the return path. It is circulateably connected to the unit.

<< Ink supply unit >>
The ink supply unit supplies the ink to the individual liquid chamber via the inflow flow path. As the ink supply unit, it is preferable that the ink is circulated between the ink ejection head and the ink ejection head via the inflow flow path and the outflow flow path by the circulation means, and the ink is sent in the outward path and the return path. It is more preferable to circulate between the ink container and the ink container via the liquid path.

<< Liquid transfer route >>
The liquid feeding route has an outward route and a returning route, and circulates the ink between the ink container and the ink supply unit.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. First, an example of the ink ejection device according to the present invention will be described with reference to FIGS. 1 and 2. Note that FIG. 1 is a schematic side view showing an example of the mechanical portion of the ink ejection device of the present invention. FIG. 2 is an explanatory plan view of a main part of the ink ejection device of FIG.

The ink ejection device is a serial type ink ejection device. The carriage 233 is slidably held in the main scanning direction by the master-slave guide rods 231 and 232 which are guide members laid horizontally on the left and right side plates 221A and 221B of the apparatus main body 201. Then, a main scanning motor (not shown) moves and scans in the direction indicated by the arrow (carriage main scanning direction) in FIG. 2 via the timing belt.

Hereinafter, the case where yellow (Y), cyan (C), magenta (M), and black (K) are used will be described, but of yellow (Y), cyan (C), magenta (M), and black (K). At least one of them contains the coloring material, an organic solvent, resin particles, an amine compound and water, the resin particles are anionic urethane resin, and the amine compound has a boiling point of 120 ° C. or higher and 200 ° C. or lower and a molecular weight of 100 or lower. It will be described as a substitute for or in addition to the ink which is an organic amine compound.

The carriage 233 is referred to as a recording head 234a or 234b (when not distinguished, it is referred to as a "recording head 234", which ejects ink droplets of each color of yellow (Y), cyan (C), magenta (M), and black (K). The same applies to the members of.). Each recording head 234 has a nozzle array composed of a plurality of nozzles arranged in a sub-scanning direction orthogonal to the main scanning direction, and is mounted with the ink droplet ejection direction facing downward.
Although the recording head 234 in the ink ejection device of the present invention has the inflow flow path for flowing ink into the individual liquid chamber and the outflow flow path for flowing ink out of the individual liquid chamber. , Details will be described later.

Each recording head 234 has two nozzle rows. Then, one nozzle row of the recording head 234a ejects a black (K) droplet, and the other nozzle row ejects a cyan (C) droplet. Further, one nozzle row of the recording head 234b ejects magenta (M) droplets, and the other nozzle row ejects yellow (Y) droplets. As the recording head 234, one having a nozzle row of each color in which a plurality of nozzles are arranged on one nozzle surface can also be used.
Further, the carriage 233 may also be referred to as an ink supply container (hereinafter, "head tank", "supply tank", or "ink tank" for supplying ink of each color corresponding to the nozzle row of the recording head 234. Yes.) It is equipped with 235a and 235b. On the other hand, ink storage containers 210y, 210m, 210c, 210k (when not distinguished, referred to as "ink storage container 210") of each color are detachably mounted on the cartridge loading unit 204. Then, the ink of each color is replenished and supplied from the ink container 210 to the head tank 235 via the supply tube 236 of each color by the supply pump unit 224.

On the other hand, as a paper feed unit for feeding the paper 242 loaded on the paper load unit (pressure plate) 241 of the paper feed tray 202, a half-month roller (feed) that separates and feeds the paper 242 from the paper load unit 241 one by one. It is provided with a separation pad 244 facing the paper roller) 243 and the paper feed roller 243. The separation pad 244 is urged to the paper feed roller 243 side.

Then, in order to feed the paper 242 fed from the paper feed unit to the lower side of the recording head 234, the guide member 245 for guiding the paper 242, the counter roller 246, the transport guide member 247, and the tip pressure roller A holding member 248 having a 249 is provided. Further, it is provided with a transport belt 251 which is a transport means for electrostatically adsorbing the fed paper 242 and transporting it at a position facing the recording head 234.

The transport belt 251 is an endless belt and is stretched on the transport roller 252 and the tension roller 253. In the transport belt 251, the transport roller 252 is rotated by driving a sub-scanning motor (not shown), and the conveyor belt 251 orbits in the belt transport direction (sub-scanning direction) shown in FIG. Further, in the vicinity of the transport roller 252, a charging roller 256, which is a charging means for charging the surface of the transport belt 251 is provided.
The charging roller 256 is arranged so as to come into contact with the surface layer of the transport belt 251 and rotate in accordance with the circumferential movement of the transport belt 251.

Further, as a paper ejection unit for ejecting the paper 242 recorded by the recording head 234, a separation claw 261 for separating the paper 242 from the transport belt 251, a paper ejection roller 262, and a spur 263 which is a paper ejection roller 263. A paper ejection tray 203 is provided below the paper ejection roller 262.

Further, a double-sided unit 271 is detachably attached to the back surface of the apparatus main body 201.
The double-sided unit 271 takes in the paper 242 conveyed by rotating the conveyor belt 251 in the reverse direction, reverses it, and feeds the paper again between the counter roller 246 and the conveyor belt 251. A manual feed tray 272 is formed on the upper surface of the double-sided unit 271.

Further, a maintenance / recovery mechanism 281 for maintaining and recovering the state of the nozzle of the recording head 234 is arranged in the non-printing area on one side of the carriage 233 in the scanning direction. The maintenance / recovery mechanism 281 includes cap members (hereinafter referred to as “caps”) 282a and 282b (hereinafter referred to as “cap 282” when not distinguished) for capping each nozzle surface of the recording head 234. .. Further, the maintenance / recovery mechanism 281 includes a wiper member (wiper blade) 283 for wiping the nozzle surface and a liquid for discharging a liquid droplet that does not contribute to recording in order to discharge the thickened recording liquid. It is equipped with an empty discharge receiver 284 that receives drops. Further, the maintenance / recovery mechanism 281 includes a carriage lock 287 that locks the carriage 233. Further, on the lower side of the maintenance / recovery mechanism 281 of the head, a waste liquid tank 300 for accommodating the waste liquid generated by the maintenance / recovery operation is replaceably mounted on the apparatus main body 201.

Further, in the non-printing area on the other side of the carriage 233 in the scanning direction, an empty space for ejecting droplets that do not contribute to recording in order to discharge the thickened recording liquid during recording or the like is received. A discharge receiver 288 is arranged. The empty discharge receiver 288 is provided with an opening 289 or the like along the nozzle row direction of the recording head 234.

In this ink ejection device configured in this way, the paper 242 is separately fed from the paper feed tray 202 one by one, and the paper 242 fed substantially vertically upward is guided by the guide 245, and the transport belt 251 and the counter. It is sandwiched between the roller 246 and transported. Further, the tip of the paper 242 is guided by the transport guide 237 and pressed against the transport belt 251 by the tip pressurizing roller 249, and the transport direction is changed by approximately 90 °.

At this time, the transport belt 251 is charged by the charging voltage pattern alternated by the charging rollers 256. When the paper 242 is fed onto the charged transport belt 251, the paper 242 is attracted to the transport belt 251 and the paper 242 is transported in the sub-scanning direction by the circumferential movement of the transport belt 251.

Therefore, by driving the recording head 234 in response to the image signal while moving the carriage 233, ink droplets are ejected onto the stopped paper 242 to record one line, and after the paper 242 is conveyed in a predetermined amount, the paper 242 is conveyed. Record the next line. When the recording end signal or the signal that the rear end of the paper 242 reaches the recording area is received, the recording operation is ended and the paper 242 is discharged to the paper output tray 203.

Next, an example of the ink ejection head in the ink ejection device of the present invention will be described with reference to FIGS. 3, 4, 5, 6, 6, 7A to 7F, 8A, and 8B. FIG. 3 is an external perspective view showing an example of an ink ejection head in the ink ejection device of the present invention. FIG. 4 is a cross-sectional explanatory view in a direction orthogonal to the nozzle arrangement direction of the ink ejection head of FIG. FIG. 5 is a partial cross-sectional explanatory view of the ink ejection head of FIG. 3 in a direction parallel to the nozzle arrangement direction. FIG. 6 is a plan view of the nozzle plate of the ink ejection head of FIG. 7A to 7F are planographic explanatory views of each member constituting the flow path member of the ink ejection head of FIG. 8A and 8B are plan explanatory views of each member constituting the common liquid chamber member of the ink ejection head of FIG.

In the ink ejection head, the nozzle plate 1, the flow path plate 2, and the diaphragm member 3 as a wall surface member are laminated and joined, and the piezoelectric actuator 11 that displaces the diaphragm member 3 and the common liquid chamber member 20 are joined. And a cover 29.

The nozzle plate 1 has a plurality of nozzles 4 for ejecting the ink.
The flow path plate 2 is formed with an individual liquid chamber 6 leading to the nozzle 4, a fluid resistance portion 7 communicating with the individual liquid chamber 6 as the inflow flow path, and a liquid introduction portion 8 communicating with the fluid resistance portion 7. Further, the flow path plate 2 is formed by laminating and joining a plurality of plate-shaped members 41 to 45 from the nozzle plate 1 side, and laminating and joining these plate-shaped members 41 to 45 and the diaphragm member 3 to form a flow path. The member 40 is configured.
The diaphragm member 3 has a filter portion 9 as an opening through the liquid introduction portion 8 and the common liquid chamber 10 formed by the common liquid chamber member 20.
The diaphragm member 3 is a wall surface member that forms the wall surface of the individual liquid chamber 6 of the flow path plate 2. The diaphragm member 3 has a two-layer structure (not limited), and is formed of a first layer that forms a thin wall portion from the flow path plate 2 side and a second layer that forms a thick wall portion, and the first layer is an individual liquid. A deformable vibration region 30 is formed in a portion corresponding to the chamber 6.

Here, as shown in FIG. 6, a plurality of nozzles 4 are arranged in a staggered pattern on the nozzle plate 1.
As shown in FIG. 7A, the plate-shaped member 41 constituting the flow path plate 2 includes a through groove portion (meaning a groove-shaped through hole) 6a constituting the individual liquid chamber 6, a fluid resistance portion 51, and the outflow flow. Through-groove portions 51a and 52a constituting the circulation flow path 52 as a path are formed.
Similarly, as shown in FIG. 7B, the plate-shaped member 42 is formed with a through groove portion 6b constituting the individual liquid chamber 6 and a through groove portion 52b constituting the circulation flow path 52.
Similarly, as shown in FIG. 7C, the plate-shaped member 43 is formed with a through groove portion 6c constituting the individual liquid chamber 6 and a through groove portion 53a having the nozzle arrangement direction constituting the circulation flow path 53 as the longitudinal direction. ..
Similarly, as shown in FIG. 7D, the plate-shaped member 44 has a through groove portion 6d constituting the individual liquid chamber 6, a through groove portion 7a forming the fluid resistance portion 7, and a through groove portion 8a constituting the liquid introduction portion 8. A through groove portion 53b having a longitudinal direction in which the nozzles are arranged to form the flow path 53 is formed.
Similarly, as shown in FIG. 7E, the plate-shaped member 45 has a through groove portion 6e constituting the individual liquid chamber 6 and a through groove portion 8b (filter downstream side liquid) having the nozzle arrangement direction constituting the liquid introduction portion 8 as the longitudinal direction. A through groove portion 53c having a longitudinal direction in the nozzle arrangement direction constituting the circulation flow path 53 is formed.
As shown in FIG. 7F, the diaphragm member 3 is formed with a vibration region 30, a filter portion 9, and a through groove portion 53d whose longitudinal direction is the nozzle arrangement direction constituting the circulation flow path 53.
In this way, by forming the flow path member by laminating and joining a plurality of plate-shaped members, it is possible to form a complicated flow path with a simple structure.

With the above configuration, the flow path member 40 composed of the flow path plate 2 and the diaphragm member 3 has a fluid resistance portion 51, a circulation flow path 52, and circulation along the surface direction of the flow path plate 2 leading to each individual liquid chamber 6. A circulation flow path 53 in the thickness direction of the flow path member 40 leading to the flow path 52 is formed. The circulation flow path 53 leads to the circulation common liquid chamber 50, which will be described later.

On the other hand, the common liquid chamber member 20 is formed with a common liquid chamber 10 to which the ink is supplied from the main tank and the ink cartridge, and a circulation common liquid chamber 50.
As shown in FIG. 8A, the first common liquid chamber member 21 has a through hole 25a for a piezoelectric actuator, a through groove portion 10a serving as a downstream common liquid chamber 10A, and a groove portion 50a having a bottom serving as a circulation common liquid chamber 50. Is formed.
As shown in FIG. 8B, the second common liquid chamber member 22 is formed with a through hole 25b for a piezoelectric actuator and a groove portion 10b that serves as a common liquid chamber 10B on the upstream side. Further, as shown in FIG. 3, the second common liquid chamber member 22 is formed with a through hole 71a which is an end portion of the common liquid chamber 10 in the nozzle arrangement direction and a supply port portion through the supply port 71.
The first common liquid chamber member 21 and the second common liquid chamber member 22 have a through hole through which the other end (the end opposite to the through hole 71a) of the circulation common liquid chamber 50 in the nozzle arrangement direction and the circulation port 81 pass through. 81a and 81b are formed.
In addition, in FIGS. 8A and 8B, the groove portion having the bottom is shown by applying a surface coating (the same applies to the following figures).
As described above, the common liquid chamber member 20 is composed of the first common liquid chamber member 21 and the second common liquid chamber member 22, and the first common liquid chamber member 21 is joined to the diaphragm member 3 side of the flow path member 40. The second common liquid chamber member 22 is laminated and joined to the first common liquid chamber member 21.

Here, the first common liquid chamber member 21 forms a downstream common liquid chamber 10A which is a part of the common liquid chamber 10 leading to the liquid introduction portion 8 and a circulation common liquid chamber 50 leading to the circulation flow path 53. ing. Further, the second common liquid chamber member 22 forms the upstream common liquid chamber 10B which is the rest of the common liquid chamber 10.
At this time, the downstream common liquid chamber 10A and the circulation common liquid chamber 50, which are a part of the common liquid chamber 10, are arranged side by side in the direction orthogonal to the nozzle arrangement direction, and the circulation common liquid chamber 50 is the common liquid chamber 10. It is placed at the position projected inside.
As a result, the size (size) of the circulation common liquid chamber 50 is restricted by the dimensions required for the flow path including the individual liquid chamber 6, the fluid resistance portion 7, and the liquid introduction portion 8 formed by the flow path member 40. Is gone.
Then, the circulation common liquid chamber 50 and a part of the common liquid chamber 10 are arranged side by side, and the circulation common liquid chamber 50 is arranged at a position projected in the common liquid chamber 10 so as to be orthogonal to the nozzle arrangement direction. The width of the head in the direction can be suppressed, and the increase in size of the head can be suppressed. The common liquid chamber member 20 forms a circulation common liquid chamber 50 with a common liquid chamber 10 to which the ink is supplied from the head tank or the ink cartridge.

On the other hand, on the side of the diaphragm member 3 opposite to the individual liquid chamber 6, a piezoelectric actuator 11 including an electromechanical conversion element as a driving means (actuator means, pressure generating means) for deforming the vibration region 30 of the diaphragm member 3 is provided. It is arranged.
As shown in FIG. 5, the piezoelectric actuator 11 has a piezoelectric member 12 joined on a base member 13, and the piezoelectric member 12 is grooved by half-cut dicing to form a required number for one piezoelectric member 12. The columnar piezoelectric elements 12A and 12B are formed in a comb-teeth shape at predetermined intervals.
Here, the piezoelectric element 12A of the piezoelectric member 12 is a piezoelectric element that is driven by giving a drive waveform, and the piezoelectric element 12B is used as a mere column without giving a drive waveform, but all the piezoelectric elements 12A and 12B are driven. It can also be used as a piezoelectric element.
Then, the piezoelectric element 12A is joined to the convex portion 30a, which is an island-shaped thick portion formed in the vibration region 30 of the diaphragm member 3. Further, the piezoelectric element 12B is joined to the convex portion 30b which is a thick portion of the diaphragm member 3.

The piezoelectric member 12 is formed by alternately stacking piezoelectric layers and internal electrodes. The internal electrodes are respectively drawn out to the end faces to provide external electrodes, and the flexible wiring member 15 is connected to the external electrodes.
In the ink ejection head configured in this way, for example, by lowering the voltage applied to the piezoelectric element 12A from the reference potential, the piezoelectric element 12A contracts, the vibration region 30 of the vibrating plate member 3 descends, and the individual liquid chamber 6 As the volume expands, the ink flows into the individual liquid chamber 6.
After that, the voltage applied to the piezoelectric element 12A is increased to extend the piezoelectric element 12A in the stacking direction, and the vibration region 30 of the vibrating plate member 3 is deformed in the direction toward the nozzle 4 to contract the volume of the individual liquid chamber 6. As a result, the ink in the individual liquid chamber 6 is pressurized, and the ink is ejected from the nozzle 4.
Then, by returning the voltage applied to the piezoelectric element 12A to the reference potential, the vibration region 30 of the vibrating plate member 3 is restored to the initial position, the individual liquid chamber 6 expands, and a negative pressure is generated. Therefore, at this time, the common liquid is generated. The ink is filled from the chamber 10 into the individual liquid chamber 6. Therefore, after the vibration of the meniscus surface of the nozzle 4 is attenuated and stabilized, the operation for the next ejection is started.
The driving method of this head is not limited to the above example (pull-pushing), and pulling or pushing may be performed depending on the driving waveform. Further, in the above-described embodiment, the laminated piezoelectric element has been described as a means for giving pressure fluctuation to the individual liquid chamber 6, but the present invention is not limited to this, and a thin-film piezoelectric element can also be used. Further, it is possible to use a heat-generating resistor arranged in the individual liquid chamber 6 to generate air bubbles by the heat generated by the heat-generating resistor to give pressure fluctuation, or to generate pressure fluctuation by using electrostatic force. ..

Next, an example of the ink circulation system using the ink ejection head according to the present embodiment will be described with reference to FIG.
FIG. 9 is a block diagram showing an example of the ink circulation system according to the present invention.
As shown in FIG. 9, the ink circulation system includes a main tank, an ink ejection head, a supply tank, a circulation tank, a compressor, a vacuum pump, a liquid feed pump, a regulator (R), a supply side pressure sensor, a circulation side pressure sensor, and the like. It is composed of. The supply-side pressure sensor is connected between the supply tank and the ink ejection head to the supply flow path side connected to the supply port 71 (see FIG. 3) of the ink ejection head. The circulation side pressure sensor is connected between the ink ejection head and the circulation tank and is connected to the circulation flow path side connected to the circulation port 81 (see FIG. 3) of the ink ejection head.
One of the circulation tanks is connected to the supply tank via the first liquid feed pump, and the other of the circulation tanks is connected to the main tank via the second liquid feed pump. As a result, the ink flows from the supply tank through the supply port 71 into the ink ejection head, is discharged from the circulation port, is discharged to the circulation tank, and is further discharged from the circulation tank to the supply tank by the first liquid feeding pump. Is sent to circulate the ink.
Further, a compressor (not shown) is connected to the supply tank, and is controlled so that a predetermined positive pressure is detected by the supply side pressure sensor. On the other hand, a vacuum pump is connected to the circulation tank, and the circulation side pressure sensor is controlled to detect a predetermined negative pressure. As a result, the negative pressure of the meniscus can be kept constant while circulating the ink through the ink ejection head.
Further, when the droplets are ejected from the nozzle of the ink ejection head, the amount of the ink in the supply tank and the circulation tank decreases, so that the second liquid feeding pump is appropriately used from the main tank to the circulation tank. It is desirable to replenish the ink. The timing of replenishing the ink from the main tank to the circulation tank is the detection of the liquid level sensor provided in the circulation tank, such as replenishing the ink when the liquid level height of the ink in the circulation tank drops below the predetermined height. It can be controlled by the result.

Next, the circulation of the ink in the ink ejection head will be described. As shown in FIG. 3, at the end of the common liquid chamber member 20, a supply port 71 communicating with the common liquid chamber and a circulation port 81 communicating with the circulation common liquid chamber 50 are formed. The supply port 71 and the circulation port 81 are connected to a supply tank and a circulation tank (see FIGS. 10 and 11) for storing the ink, respectively, via a tube. Then, the ink stored in the supply tank is supplied to the individual liquid chamber 6 via the supply port 71, the common liquid chamber 10, the liquid introduction unit 8, and the fluid resistance unit 7.
Further, while the ink in the individual liquid chamber 6 is ejected from the nozzle 4 by the drive of the piezoelectric element 12, a part or all of the ink staying in the individual liquid chamber 6 without being ejected is a fluid resistance portion 51. It is circulated to the circulation tank via the circulation flow paths 52 and 53, the circulation common liquid chamber 50, and the circulation port 81.
The ink circulation can be performed not only when the ink ejection head is operated but also when the operation is stopped. By circulating the ink when the operation is stopped, the ink in the individual liquid chamber is constantly refreshed, and the aggregation and sedimentation of the components contained in the ink can be suppressed, which is preferable.

<Discharge control>
In such an ink ejection head, for example, as shown in FIG. 12, by lowering the voltage applied to the piezoelectric member 112 from the reference potential Ve, the piezoelectric member 112 contracts, the diaphragm member 102 deforms, and the individual liquid is formed. The volume of the chamber 105 expands. As a result, the ink flows into the individual liquid chamber 105.

After that, as shown in FIG. 13, the voltage applied to the piezoelectric member 112 is increased to extend the piezoelectric member 112 in the stacking direction, and the diaphragm member 102 is deformed in the nozzle 104 direction to contract the volume of the individual liquid chamber 105. .. As a result, the ink in the individual liquid chamber 105 is pressurized, and the droplet 301 is ejected from the nozzle 104.

Then, by returning the voltage applied to the piezoelectric member 112 to the reference potential Ve, the diaphragm member 102 is restored to the initial position, the individual liquid chamber 105 expands, and a negative pressure is generated. Therefore, at this time, the common liquid chamber 110 The individual liquid chamber 105 is filled with ink. Therefore, after the vibration of the meniscus surface of the nozzle 104 is attenuated and stabilized, the operation for the next droplet ejection is started.

The printed matter is not particularly limited and is not limited to that used as a general recording medium, and building materials such as wallpaper and flooring, cloth for clothing, textiles, leather and the like can be appropriately used. Further, ceramics, glass, and metal can be used by adjusting the configuration of the path for transporting the printed matter. Examples of the recording medium include the following.

<Recording medium>
The recording medium used for recording is not particularly limited, and examples thereof include plain paper, glossy paper, special paper, cloth, film, transparency sheet, and general-purpose printing paper.

<Printed matter>
A printed matter can be obtained by providing a printed layer on an object to be recorded such as a recording medium by using the ink ejection device and the ink ejection method of the present invention.

Hereinafter, examples of the present invention will be described, but the present invention is not limited to these examples. Unless otherwise specified, parts in the following description indicate parts by mass.

<Preparation of resin particles>
(Preparation Example 1)
-Preparation of surface-modified black pigment dispersion liquid 1 (self-dispersion type pigment dispersion liquid 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) manufactured by Cabot Corporation, 100 mmol of sulfanilic acid and 1 L of ion-exchanged high pure water were mixed with a Silverson mixer (6000 rpm) in a room temperature environment. If the pH of the resulting slurry is higher than 4, 100 mmol nitric acid is added. After 30 minutes, sodium nitrite (100 mmol) dissolved in a small amount of ion-exchanged high pure water was slowly added to the mixture. Further, the mixture was heated to 60 ° C. with stirring and reacted for 1 hour. A modified pigment in which sulfanilic acid was added to carbon black could be produced. Then, the pH was adjusted to 9 with a 10% tetrabutylammonium hydroxide solution (methanol solution) to obtain a modified pigment dispersion after 30 minutes. Ultrafiltration using a dialysis membrane using a dispersion containing a pigment bonded to at least one sulfanic acid group or a tetrabutylammonium sulfate salt and ion-exchanged high-pure water was performed, and then ultrasonic dispersion was performed to obtain the pigment solid content. Was concentrated to 20% to obtain a modified pigment dispersion. The surface treatment level was 0.75 mmol / g, and the particle size (D50) measured by a particle size distribution measuring device (Nanotrack UPA-EX150 manufactured by Nikkiso Co., Ltd.) was 120 nm.

(Preparation Example 2)
-Preparation of surface-modified black pigment dispersion liquid 2 (self-dispersion type pigment dispersion liquid 2)-
Add 1 L of ion-exchanged high pure water and 1 mol of 4-aminobenzoic acid to 500 g of ^{Black Pearls (registered trademark) 880 (BET surface area 220 m 2} / g and DBPA 105 mL / 100 g) manufactured by Cabot Corporation to a ProcessAll 4HV mixer (4 L). bottom. The mixture was then vigorously mixed at 300 rpm for 10 minutes while warming to 60 ° C.
To this was added a 20% aqueous solution of sodium nitrite [1 molar equivalent based on 4-aminobenzoic acid] over 15 minutes. The mixture was mixed and stirred for 3 hours while warming to 60 ° C. The reaction product was taken out while diluting with 750 mL of ion-exchanged high pure water. The pH was then adjusted to 9 with a 10% tetrabutylammonium hydroxide solution (methanol solution) to give the modified pigment dispersion after 30 minutes. Ultrafiltration using a dialysis membrane was performed using a dispersion containing a pigment bonded to at least one aminobenzoic acid group or a tetrabutylammonium salt of aminobenzoic acid obtained and ion-exchanged high-pure water, and further ultrasonic dispersion was performed. This was carried out to obtain a modified pigment dispersion in which the pigment solid content was concentrated to 20%. The surface treatment level was 0.5 mmol / g, and the particle size (D50) measured by a particle size distribution measuring device (Nanotrack UPA-EX150 manufactured by Nikkiso Co., Ltd.) was 104 nm.

(Preparation Example 3)
-Preparation of black pigment-containing polymer fine particle dispersion (resin-coated pigment dispersion 1))-
--Preparation of polymer solution A ---
After sufficiently substituting nitrogen gas in a 1 L flask equipped with a mechanical stirrer, a thermometer, a nitrogen gas introduction tube, a reflux tube, and a dropping funnel, 11.2 g of styrene, 2.8 g of acrylic acid, and 12.0 g of lauryl methacrylate. , 4.0 g of polyethylene glycol methacrylate, 4.0 g of styrene macromer, and 0.4 g of mercaptoethanol were mixed and heated to 65 ° C. Next, 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, and azobismethylvalero. A mixed solution of 2.4 g of nitrile and 18 g of methyl ethyl ketone was added dropwise into the flask over 2.5 hours. After the 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 the mixture was further aged for 1 hour. After completion of the reaction, 364 g of methyl ethyl ketone was added into the flask to obtain 800 g of the 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 and C.I. I. After sufficiently stirring 42 g of carbon black (FW100 manufactured by Degussa), 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, the mixture was kneaded using a roll mill. The obtained paste was put into 200 g of pure water, stirred sufficiently, and then methyl ethyl ketone and water were distilled off using an evaporator, and this dispersion was used with a polyvinylidene fluoride having an average pore size of 5.0 μm in order to remove coarse particles. Pressurization was performed with a membrane filter to obtain 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.
The particle size (D50) of the polymer fine particles in the carbon black pigment-containing polymer fine particle dispersion was 104 nm when measured with a particle size distribution measuring device (Nanotrack UPA-EX150, manufactured by Nikkiso Co., Ltd.).

(Preparation Example 4)
-Preparation of cyan pigment-containing polymer fine particle dispersion (resin-coated pigment dispersion 2)-
Organic solvent (methyl ethyl ketone) 20 g, polymerization chain transfer agent (2-mercaptoethanol) 0.03 g, polymerization initiator, methacrylic acid 10 g, styrene monomer 22.5 g, polyethylene glycol monomethacrylate (ethylene oxide = 15) 2.5 g, 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 under stirring at 75 ° C. to polymerize each monomer. It was 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).
The polymer solution obtained as the water-insoluble polymer solution (1) was dried under reduced pressure, 5 g of the obtained solution was dissolved in 15 g of methyl ethyl ketone, and the polymer was neutralized with an aqueous sodium hydroxide solution. Furthermore, C.I. I. 15 g of Pigment Blue 15: 3 was added, and the mixture was kneaded with a disperser while adding water.
After adding 100 g of ion-exchanged water to the obtained kneaded product and stirring the mixture, the methyl ethyl ketone is removed at 60 ° C. under reduced pressure, and a part of the water is further removed to obtain a cyan pigment-containing polymer having a solid content concentration of 15% by mass. Fine particle dispersion liquid A cyan resin-coated pigment dispersion liquid was obtained. (Pigment: water-insoluble polymer = 1: 0.3) The volume average particle size of the pigment in this dispersion was 91 nm.

(Preparation Example 5)
-Preparation of surfactant-dispersed black pigment dispersion (surfactant-dispersed pigment dispersion 1)-
175 parts of carbon black (NIPEX160, manufactured by Degussa, BET specific surface area 150 m ² / g,
Average primary particle size 20 nm, pH 4.0, DBP oil absorption 620 g / 100 g)
175 parts of sodium naphthalene sulfonic acid formalin condensate (Pionin A-45-PN manufactured by Takemoto Oil & Fat Co., Ltd., naphthalene sulfonic acid dimer,
Total content of trimers and tetramers = 50% by mass)
650 parts of distilled water The above mixture was premixed to prepare a mixed slurry (a). This was circulated and dispersed for 3 minutes at a peripheral speed of 10 m / s and a liquid temperature of 10 ° C. using a disk-type media mill (DMR type manufactured by Ashizawa Finetech Co., Ltd.) using 0.05 mm zirconia beads and a filling rate of 55%. The coarse particles were centrifuged with a centrifuge (Model-7700, manufactured by Kubota Shoji Co., Ltd.) to obtain a surfactant-dispersed pigment dispersion having a pigment concentration of 13% by mass.

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

(Preparation Example 7)
-Preparation of aqueous dispersion of polycarbonate urethane resin 2-
An aqueous dispersion of the polycarbonate-based urethane 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 the polyurethane resin 2 was measured by a particle size distribution measuring device (Nanotrack UPA-EX150, manufactured by Nikkiso Co., Ltd.) and found to be 23 nm.

(Preparation Example 8)
-Preparation of aqueous dispersion of polycarbonate urethane resin 3-
An aqueous dispersion of the polycarbonate-based urethane 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 the polyurethane resin 3 was measured by a particle size distribution measuring device (Nanotrack UPA-EX150, manufactured by Nikkiso Co., Ltd.) and found to be 34 nm.

(Preparation Example 9)
-Preparation of aqueous dispersion of polycarbonate urethane resin 4-
An aqueous dispersion of the polycarbonate-based urethane 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 the polyurethane resin 4 was measured by a particle size distribution measuring device (Nanotrack UPA-EX150, manufactured by Nikkiso Co., Ltd.) and found to be 49 nm.

(Preparation Example 10)
-Preparation of an aqueous dispersion of polycarbonate urethane resin 5-
An aqueous dispersion of the polycarbonate-based urethane 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 the polyurethane resin 5 was measured by a particle size distribution measuring device (Nanotrack UPA-EX150, manufactured by Nikkiso Co., Ltd.) and found to be 70 nm.

(Preparation Example 11)
-Preparation of an aqueous dispersion of polycarbonate urethane resin 6-
An aqueous dispersion of the polycarbonate-based urethane 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 the polyurethane resin 6 was measured by a particle size distribution measuring device (Nanotrack UPA-EX150, manufactured by Nikkiso Co., Ltd.) and found to be 89 nm.

(Preparation Example 12)
-Preparation of an aqueous dispersion of polycarbonate urethane resin 7-
An aqueous dispersion of the polycarbonate-based urethane 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 the polyurethane resin 7 was measured by a particle size distribution measuring device (Nanotrack UPA-EX150, manufactured by Nikkiso Co., Ltd.) and found to be 121 nm.

(Preparation Example 13)
-Acrylic-Preparation of water dispersion of silicone resin-
After sufficiently substituting nitrogen gas in a 1 L flask equipped with a mechanical stirrer, a thermometer, a nitrogen gas introduction tube, a reflux tube, and a dropping funnel, 17.5 g of Latemul S-180 and 350 g of ion-exchanged water are added and mixed. Then, the temperature was raised to 65 ° C.
After raising the temperature, 3.0 g of the reaction initiator t-butylperoxobenzoate and 1.0 g of sodium isoascorbate are added, and after 5 minutes, 45 g of methyl methacrylate, 160 g of -2-ethylhexyl methacrylate, 5 g of acrylic acid, and methacrylic acid are added. Butyl acid (45 g), cyclohexyl methacrylate (30 g), vinyltriethoxysilane (15 g), Latemul S-180 (8.0 g), and ion-exchanged water (340 g) were mixed and added dropwise over 3 hours. Then, after heating and aging at 80 ° C. for 2 hours, the mixture was cooled to room temperature and the pH was adjusted to 7 to 8 with sodium hydroxide. Ethanol was distilled off using an evaporator, and the water content was adjusted to prepare 730 g of a solution of an acrylic silicone resin aqueous dispersion having a solid content of 40% by mass. The particle size (D50) of the acrylic silicone resin aqueous dispersion 1 was measured by a particle size distribution measuring device (Nanotrack UPA-EX150, manufactured by Nikkiso Co., Ltd.) and found to be 43 nm.

<Ink preparation example>
-Ink preparation-
The contents of the resin particles shown below are all solid content only.
The molecular weight and boiling point of the amine compound used in the preparation of the ink are as follows.
Diethylamine (molecular weight 73.14) 55 ° C
Triethylamine (molecular weight 101.19) 89 ° C
Dimethylethanolamine (molecular weight 89.14) 133 ° C.
Aminomethyl propanol (molecular weight 89.14) 165 ° C
Piperazine (molecular weight 86.14) 144 ° C.
Aminomethyl propanediol (molecular weight 105.14) 152 ° C

<Ink Preparation Example 1>
2.0.00 parts of 1.3-butanediol, 10.00 parts of 3-methyl-1.3-butanediol, 8.00 parts of glycerin and 2-ethyl-1.3-hexanediol in a container equipped with a stirrer. Add 00 parts and 0.50 parts of surfactant and stir for about 30 minutes to make it uniform. Next, 37.50 parts of the self-dispersion type pigment dispersion liquid 1 and high pure water are added, and the mixture is stirred for about 60 minutes to make it uniform. Further, 4.50 parts of polycarbonate urethane resin 4 (Preparation Example 9) is added in terms of solid content, and the mixture is stirred for 30 minutes to make the ink uniform. This ink was pressure-filtered with a polyvinylidene fluoride membrane filter having an average pore diameter of 1.2 μm to remove coarse particles and dust to prepare the ink of Ink Preparation Example 1. High pure water was added so that the total amount was 100 parts.
The following fluorine-based surfactant FS-300 was used as the surfactant.
* Fluorine-based surfactant FS-300
Polyoxyalkylene (C _{2 to} C ₃ ) -2-perfluoroalkyl (C _{4 to} C ₁₆ ) Ethyl ether (manufactured by DuPont, trade name "FS-300", solid content 40%)

<Ink Preparation Examples 2 to 25, Ink Comparative Preparation Examples 1 to 4>
Similar to Ink Preparation Example 1, the water-soluble organic solvents and surfactants shown in Tables 1 to 3 below are mixed and stirred, water-dispersible coloring material (pigment dispersion) and high pure water are added and mixed and stirred, and further. The water-dispersible resin was mixed and stirred to make the ink uniform, and the inks of Ink Preparation Examples 2 to 25 and Ink Comparative Preparation Examples 1 to 4 were prepared. The numerical values of the addition amount of the water-dispersible resin shown in Tables 1 to 3 are the numerical values in terms of solid content. In the ink preparation examples 20 to 25, the defoaming agent is added, and the defoaming agent is added together with the surfactant. The following defoaming agents were used.
* Antifoaming agent Envilogem AD01
2,4,7,9-Tetramethyl-4,7-decanediol Manufactured by Nissin Chemical Industry Co., Ltd., trade name "Enviroguem AD01"
Refer to Tables 1 to 3 for the amount of addition. In Ink Preparation Example 24, not only the above-mentioned fluorine-based surfactant FS-300 but also an acetylene glycol-based surfactant was added in combination.
* Acetylene glycol-based surfactant:
See Tables 1 to 3 for the amount of 2,4,7,9-tetramethyl-5-decyne-4,7-diol added. Pressurize this ink with a polyvinylidene fluoride membrane filter having an average pore size of 1.2 μm. The inks of Ink Preparation Examples 2 to 25 and Ink Comparative Preparation Examples 1 to 4 were prepared by filtering and removing coarse particles and dust.

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

Next, the ink physical characteristics of the inks of Ink Preparation Examples 1 to 25 and Ink Comparative Preparation Examples 1 to 4 were measured by the evaluation methods shown below.
The results are shown in Table 4.
-Ink physical characteristics-
<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 Corporation).

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

<Liquidity during water evaporation>
The inks of the ink preparation examples and the comparative preparation examples were weighed and weighed in a glass petri dish having a diameter of 33 mm with a precision precision precision electronic balance capable of measuring up to four decimal places. Then, it was stored at normal pressure in an ESPEC constant temperature and humidity chamber (ModelPL-3KP) having a temperature of 32 ± 0.5 ° C. and a humidity of 30 ± 5%, and after 24 hours, individual samples were taken out and weighed. 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: Within 5 seconds after scratching, the bottom of the petri dish is filled with ink and disappears.
B: Within 60 seconds after scratching, the bottom of the petri dish is filled with ink and becomes invisible.
C: The bottom of the petri dish is still visible 2 minutes or more after scratching.

<Flow rate change rate when 30% water evaporates>
In the inks of the ink preparation example and the comparative preparation example, the flow rates when passing through a tube having an inner diameter of 2 mm under a constant pressure in the initial state (when 0% water evaporates) and when 30% water evaporates are measured. The rate of change was calculated.
A: 30% water flow rate compared to the initial state is one-third or more B: 30% water flow rate compared to the initial state is one-fifth or more C: 30% water flow rate compared to the initial state Flow rate during evaporation is less than 1/10

<Ink storage stability>
Each ink was placed in a polyethylene container, sealed, stored at 70 ° C. for 2 weeks, and then the pigment particle size (D50) and viscosity were measured and evaluated as follows based on the rate of change from the initial physical properties.
A: Both change rate of 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 foaming property>
According to JISK3362-1998,8.5, the height of bubbles generated when 200 ml of evaluation ink was dropped onto the water surface from a height of 900 mm at 25 ° C. for 30 seconds was measured.
From the viewpoint of discharge stability, the foam height is required to be 45 mm or less, the foam height is preferably 30 mm or less, and more preferably 15 mm or less.

<Measurement of surface tension of ink>
A fully automatic tensiometer (CBVP-Z, manufactured by Kyowa Interface Science Co., Ltd.) was used to measure the static surface tension of the evaluation ink at 25 ° C.

<Examples 1 to 25, Comparative Examples 1 to 6>
By the image forming step shown below, each ink was ejected to a recording medium using the ejection device A or the ejection device B below to form an image.
Discharge device A: A modified machine equipped with a circulation mechanism on Ricoh's IPSiO GXe-5500 Discharge device B: Ricoh's IPSiO GXe-5500
-Image formation process-
Under environmental conditions adjusted to 23 ± 0.5 ° C. and 50 ± 5% RH, the ink ejection amount was equalized using the ejection device A and the ejection device B equipped with the circulation type heads shown in FIGS. 3 to 13. The drive voltage of the piezo element was changed so that the ink would adhere to the recording medium with the same amount of ink. Next, the printing modes of the ejection device A and the ejection device B were set to "plain paper fast" and "glossy paper fast" to form an image.
The ink ejection properties and the obtained images in Examples and Comparative Examples were evaluated by the following evaluation methods.

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

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

<Discharge stability>
200 charts continuously filled with a solid image of 5% of the area of A4 size paper per color created by Microsoft Word2000 were printed on My Paper (manufactured by Ricoh Co., Ltd.), and evaluated from the ejection disturbance of each nozzle after printing. For the print mode, the driver attached to the printer used a mode in which the "plain paper-standard fast" mode was modified to "no color correction" from the user settings for plain paper.
〔Evaluation criteria〕
A: No discharge turbulence B: Slight discharge turbulence C: Discharge turbulence or part not discharged

<Image density measurement>
The ink produced in the color inkjet printer was filled, and the image output evaluation was performed under the following conditions.
<Printing conditions>
Evaluation printer: IPSIO GX E5500 (manufactured by Ricoh Corporation)
Evaluation paper: My Paper (manufactured by Ricoh Co., Ltd.) (plain paper)
Chart: Black single color solid patch printing mode: Clean mode In the above chart, the black density was measured with a reflection spectrophotometer (Model: 939 manufactured by X-Rite).

〔式（Ｖ）中、Ｒ₁及びＲ₂はアルキル基を表す。〕
（１２）前記インクは、更に、フッ素系の界面活性剤と下記一般式（VII）で表される化合物を含有する上記（１）乃至（１１）のいずれかに記載のインク吐出装置。

〔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。〕
（１３）前記インクは、フッ素系界面活性剤、フッ素系以外の界面活性剤、及び抑泡剤を含有する上記（１）乃至（１２）のいずれかに記載のインク吐出装置。
（１４）前記インクは、３０％水分蒸発時の粘度増加率が４００％以下である上記（１）乃至（１３）のいずれかに記載のインク吐出装置。
（１５）前記循環手段が、前記インクを前記個別液室から流出させる負圧を発生する負圧発生手段、及び前記インクを前記個別液室に流入させる正圧を発生する正圧発生手段を有する上記（１）乃至（１４）のいずれかに記載のインク吐出装置。
（１６）インクを収容するインク収容容器と、該インク収容容器から供給されるインクを吐出する吐出ヘッドと、を備えたインク吐出装置を用いたインク吐出方法であって、前記吐出ヘッドは、個別液室と、前記インクを個別液室に流入させる流入経路と、前記インクを前記個別液室から流出させる流出経路と、前記インクを吐出するノズルとを備えており、前記吐出ヘッドには前記流出流路から流出した前記インクを前記流入流路に向かって循環させる循環手段が設けられており、前記インクは、色材、有機溶剤、樹脂粒子、アミン化合物及び水を含有し、前記樹脂粒子がアニオン性ウレタン樹脂のみであり、前記樹脂粒子の前記インクにおける含有量(質量基準)を１とした場合に、前記アミン化合物の含有量が０．０１以上０．０８以下であり、前記アミン化合物が沸点１２０℃以上２００℃以下、且つ分子量１００以下の有機アミン化合物であるインク吐出方法。
Examples of embodiments of the present invention are as follows.
(1) An ink ejection device including an ink accommodating container for accommodating ink and an ejection head for ejecting ink supplied from the ink accommodating container. The ejection head includes an individual liquid chamber and the ink. It is provided with an inflow path for inflowing the ink into the individual liquid chamber, an outflow path for the ink to flow out from the individual liquid chamber, and a nozzle for ejecting the ink.
The ink ejection device is provided with a circulation means for circulating the ink flowing out from the outflow flow path toward the inflow flow path.
The ink contains a coloring material, an organic solvent, resin particles, an amine compound and water, the resin particles are only anionic urethane resin, and the content (mass standard) of the resin particles in the ink is 1. In some cases, the amine compound is an organic amine compound having a content of 0.01 or more and 0.08 or less , a boiling point of 120 ° C. or more and 200 ° C. or less, and a molecular weight of 100 or less, and the ink of the amine compound. An ink ejection device having a content of 0.01% by mass or more and 0.8% by mass or less.
(2) The ink ejection device according to (1) above, wherein the content of the amine compound in the ink is 0.06% by mass or more and 0.5% by mass or less.
( 3 ) The ink ejection device according to (1) or (2) above, wherein the particle size (D50) of the resin particles is 10 nm or more and 100 nm or less.
( 4 ) The ink ejection device according to any one of (1) to (3 ) above, wherein the particle size (D50) of the resin particles is 10 nm or more and 50 nm or less.
( 5 ) The ink ejection device according to any one of (1) to (4 ) above, wherein the resin particles are an anionic polycarbonate-based urethane resin or an anionic polyester-based urethane resin.
( 6 ) The ink ejection device according to any one of (1) to (5 ) above, wherein the organic solvent is 30 to 50% by mass of the entire ink.
( 7 ) The ink ejection device according to any one of (1) to (6 ) above, wherein the coloring material is a self-dispersing color material having a functional group.
( 8 ) The ink ejection device according to any one of (1) to (6 ) above, wherein the coloring material is a resin-coated color material.
( 9 ) Any of the above (1) to (8 ) in which the content of the resin particles is 0.05 or more and 2 or less when the content (mass standard) of the coloring material in the ink is 1. The ink ejection device described.
( 10 ) The ink ejection device according to any one of (1) to (9 ) above, wherein the static surface tension of the ink at 25 ° C. is 20 mN / m or more and 27 mN / m or less.
( 11 ) The ink ejection device according to any one of (1) to (10 ) above, 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 represent an alkyl group. ]
( 12 ) The ink ejection device according to any one of (1) to (11 ) above, 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 alkyl groups having 3 to 6 carbon atoms independently, and R ₁₂ and R ₁₃ are alkyl groups having 1 to 2 carbon atoms independently. , N is an integer of 1 to 6. ]
( 13 ) The ink ejection device according to any one of (1) to (12 ) above, wherein the ink contains a fluorine-based surfactant, a non-fluorine-based surfactant, and a defoaming agent.
( 14 ) The ink ejection device according to any one of (1) to (13 ) above, wherein the ink has a viscosity increase rate of 400% or less at the time of evaporation of 30% water.
( 15 ) The circulation means has a negative pressure generating means for generating a negative pressure for causing the ink to flow out from the individual liquid chamber, and a positive pressure generating means for generating a positive pressure for causing the ink to flow into the individual liquid chamber. The ink ejection device according to any one of (1) to ( 14) above.
( 16 ) An ink ejection method using an ink ejection device including an ink containing container for accommodating ink and an ejection head for ejecting ink supplied from the ink containing container, wherein the ejection heads are individually used. The liquid chamber, an inflow path for flowing the ink into the individual liquid chamber, an outflow path for discharging the ink from the individual liquid chamber, and a nozzle for ejecting the ink are provided, and the discharge head is provided with the outflow. A circulation means for circulating the ink flowing out of the flow path toward the inflow flow path is provided, and the ink contains a coloring material, an organic solvent, resin particles, an amine compound and water, and the resin particles contain the resin particles. It is only an anionic urethane resin , and 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 0.08 or less , and the amine compound is An ink ejection method that is an organic amine compound having a boiling point of 120 ° C. or higher and 200 ° C. or lower and a molecular weight of 100 or lower.

(About Figures 1 and 2)
201 Device body 202 Paper feed tray 203 Paper discharge tray 204 Cartridge loading section 210, 210y, 210m, 210c, 210k Ink storage container 221A, 221B Side plate 224 Supply pump unit 231, 232 Guide rod 233 Carrying 234a, 234b Recording head 234 Recording head 235a, 235b Ink supply container 235 Head tank 236 Supply tube 237 Transport guide 241 Paper loading section (pressure plate)
242 Paper 243 Paper feed roller (half moon roller)
244 Separation pad 245 Guide member 246 Counter roller 247 Conveyance guide member 248 Retaining member 249 Tip pressurizing roller 251 Conveying belt 252 Conveying roller 253 Tension roller 256 Charging roller 261 Separation claw 262 Paper ejection roller 263 Spur 271 Double-sided unit 272 Manual feed tray 281 Maintenance Recovery mechanism 282, 282a, 282b Cap (cap member)
283 Wiper member (wiper blade)
284 Empty discharge receiver 287 Carriage lock 288 Empty discharge receiver 289 Opening 300 Waste liquid tank

(Figs. 3 to 13) 1 Nozzle plate 2 Flow plate 3 Vibrating plate member 4 Nozzle 6 Individual liquid chambers 6a, 6b, 6c, 6d, 6e Through groove 7 Fluid resistance 7a Through groove 8 Liquid introduction 8a Through groove 8b Through groove 9 Filter section 10 Common liquid chamber 10A Downstream side common liquid chamber 10a Through groove section 10B Upstream side common liquid chamber 10b Groove section 11 Hydraulic actuator 12 Hydraulic member 12A, 12B Hydraulic element 13 Base member 14 Nozzle 15 Flexible wiring member 20 Common liquid chamber Member 21 First common liquid chamber member 22 Second common liquid chamber member 25a, 25b Through hole 29 for piezoelectric actuator Cover 30 Vibration region 30a, 30b Convex portion 40 Flow path member 41, 42, 43, 44, 45 Plate-shaped member 50 Circulation common liquid chamber 50a Groove 51 Fluid resistance 51a Through groove 52 Circulation flow path 52a, 52b Through groove 53 Circulation flow path 53a, 53b, 53c, 53d Through groove 71 Supply port 71a Through hole 81 Circulation port 81a, 81b Through hole 102 Sliding plate member 104 Nozzle 105 Individual liquid chamber 110 Common liquid chamber 112 Hydraulic member 301 Droplet

Japanese Patent Publication No. 2000-507522

Claims (16)

An ink ejection device including an ink accommodating container for accommodating ink and an ejection head for ejecting ink supplied from the ink accommodating container, wherein the ejection head has an individual liquid chamber and the ink as an individual liquid. The ink ejection device includes an inflow path for flowing into the chamber, an outflow path for ejecting the ink from the individual liquid chamber, and a nozzle for ejecting the ink, and the ink ejection device receives the ink discharged from the outflow channel. A circulation means for circulating toward the inflow flow path is provided, and the ink contains a coloring material, an organic solvent, resin particles, an amine compound and water, and the resin particles are only anionic urethane resin. 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 0.08 or less , and the amine compound has a boiling point of 120 ° C. or more and 200 ° C. or less. An ink ejection device which is an organic amine compound having a molecular weight of 100 or less and in which the content of the amine compound in the ink is 0.01% by mass or more and 0.8% by mass or less. The ink ejection device according to claim 1, wherein the content of the amine compound in the ink is 0.06% by mass or more and 0.5% by mass or less. The ink ejection device according to claim 1 or 2 , wherein the particle size (D50) of the resin particles is 10 nm or more and 100 nm or less. The ink ejection device according to any one of claims 1 to 3 , wherein the particle size (D50) of the resin particles is 10 nm or more and 50 nm or less. The ink ejection device according to any one of claims 1 to 4 , wherein the resin particles are an anionic polycarbonate-based urethane resin or an anionic polyester-based urethane resin. The ink ejection device according to any one of claims 1 to 5 , wherein the organic solvent is 30 to 50% by mass of the whole ink. The ink ejection device according to any one of claims 1 to 6 , wherein the coloring material is a self-dispersing color material having a functional group. The ink ejection device according to any one of claims 1 to 6 , wherein the coloring material is a resin-coated color material. The ink ejection according to any one of claims 1 to 8 , wherein the content of the resin particles is 0.05 or more and 2 or less when the content (mass standard) of the coloring material in the ink is 1. Device The ink ejection device according to any one of claims 1 to 9 , wherein the static surface tension of the ink at 25 ° C. is 20 mN / m or more and 27 mN / m or less. The ink ejection device 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 (V).

[In formula (V), R ₁ and R ₂ represent an alkyl group. ] The ink ejection device according to any one of claims 1 to 11 , further comprising a fluorine-based surfactant and a compound represented by the following general formula (VII).

[In formula (VII), R ₁₀ and R ₁₁ are alkyl groups having 3 to 6 carbon atoms independently, and R ₁₂ and R ₁₃ are alkyl groups having 1 to 2 carbon atoms independently. , N is an integer of 1 to 6. ] The ink ejection device according to any one of claims 1 to 12 , wherein the ink contains a fluorine-based surfactant, a non-fluorine-based surfactant, and a defoaming agent. The ink ejection device according to any one of claims 1 to 13 , wherein the ink has a viscosity increase rate of 400% or less when 30% water evaporates. Claim 1 in which the circulation means includes a negative pressure generating means for generating a negative pressure for causing the ink to flow out of the individual liquid chamber, and a positive pressure generating means for generating a positive pressure for causing the ink to flow into the individual liquid chamber. The ink ejection device according to any one of items 14 to 14. An ink ejection method using an ink ejection device including an ink containing container for accommodating ink and an ejection head for ejecting ink supplied from the ink containing container, wherein the ejection head is an individual liquid chamber. The ink is provided with an inflow path for inflowing the ink into the individual liquid chamber, an outflow path for the ink to flow out from the individual liquid chamber, and a nozzle for ejecting the ink, and the ejection head is provided with the outflow flow path. A circulation means for circulating the outflowed ink toward the inflow flow path is provided, and the ink contains a coloring material, an organic solvent, resin particles, an amine compound and water, and the resin particles are anionic urethane. When it is only a resin and 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 0.08 or less, and the amine compound has a boiling point of 120 ° C. An ink ejection method which is an organic amine compound having a temperature of 200 ° C. or lower and a molecular weight of 100 or less, and the content of the amine compound in the ink is 0.01% by mass or more and 0.8% by mass or less.

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