JP2020117683A - Ink, method of manufacturing ink, printing method, and printing device - Google Patents

Abstract

To provide an ink which has both fixability and liquid permeability, and an ink which has high image density, excellent liquid permeability, and excellent discharge stability.SOLUTION: An ink contains water, an organic solvent, a polyurethane resin, and a cyclic ester including a structure represented by general formula (I) in the figure, where the content of the cyclic ester having a crystal with a particle diameter of 1 μm or more is less than 4 ppm of the total of the ink after the ink is stored to stand in a normal temperature environment (25±5°C) for one month.SELECTED DRAWING: None

Description

The present invention relates to an ink, a method for manufacturing the ink, a printing method, and a printing apparatus.

Ink jet recording methods have become rapidly popular in recent years because they can easily record color images and have low running costs. However, this method has a problem that an image defect represented by a character blur easily occurs depending on a combination of the ink and the recording medium, and the image quality is significantly deteriorated.
For example, since non-penetrating media for signage does not absorb ink, it is a problem that the image does not bleed severely and is not fixed.
Further, when recording is performed on a coated paper using a filler such as calcium carbonate or kaolin as a coating layer material such as a coated paper for commercial printing or publication printing, an image is drastically blurred or a density is not expressed.

Therefore, in order to improve the drying property and the fixing property, a hydrophobic organic solvent such as an organic solvent having an SP value of 8.9 to 12.0 or an organic solvent having a high vapor pressure is used as the organic solvent, and water-dispersible resin particles are further added. The ink composition is changing in the direction of more use.

Further, since the non-penetrable media for signage has poor ink fixability, it is necessary to select the material of the water-dispersible resin particles, and the addition amount thereof is increasing. In particular, in order to improve the fixing property of the ink to the film of the non-penetrable media, the number of cases in which polyurethane resin particles synthesized from a polyol raw material containing an aromatic ring are often used as an ink component is increasing.
Although the image quality is improved by the above-mentioned change in the situation, problems occur in the ink storage stability, liquid permeability, and ejection stability.

Further, Patent Document 1 discloses an invention relating to a water-based inkjet ink that is excellent in drying stability and printing fixability when printed on the surface of a hydrophobic resin medium, and is also excellent in dispersion stability of a resin binder. It is disclosed. Then, in claim 1, it is defined that an amide solvent having a specific structure, an aqueous emulsion polymer, and a crosslinking agent for the polymer are contained.

An object of the present invention is to provide an ink that has both fixability and liquid permeability.

The above problem is solved by the invention <1> below.
<1> In an ink containing water, an organic solvent, and polyurethane resin particles, the ink contains a cyclic ester having a structure represented by the following general formula (I), and the ink is 1 at room temperature (25±5° C.). An ink in which the content of crystals of the cyclic ester having a particle size of 1 μm or more is less than 4 ppm of the entire ink after storage for a month.

According to the present invention, it is an object of the present invention to provide an ink having both fixability and liquid permeability.

FIG. 1 is a diagram showing an example of a printing apparatus of the present invention. FIG. 2 is a diagram showing an example of a recording apparatus using the ink of the present invention. FIG. 3 is a perspective view of a main tank that stores the ink of the present invention. FIG. 4 is an exploded perspective view showing an example of the ink ejection head used in the present invention. FIG. 5 is a cross-sectional explanatory diagram along the liquid chamber longitudinal direction of the same ink discharge head. FIG. 6 is a cross-sectional explanatory diagram along the lateral direction of the liquid chamber of the same ink ejection head. FIG. 7 is a plan view of the nozzle plate of the ink ejection head. FIG. 8 is a sectional explanatory view of the nozzle plate shown in FIG. 7. FIG. 9 is an enlarged cross-sectional explanatory view of one nozzle portion.

Hereinafter, the present invention <1> will be described in detail. Further, the present invention relates to the following <1>, but the embodiments thereof also include the following <2> to <21>, and therefore these will also be described.
<1>
In an ink containing water, an organic solvent and polyurethane resin particles, the ink contains a cyclic ester having a structure represented by the following general formula (I), and the ink is allowed to stand for 1 month in a room temperature environment (25±5° C.). An ink in which the content of crystals of the cyclic ester having a particle size of 1 μm or more is less than 4 ppm of the entire ink after storage.
<2>
The ink according to <1>, wherein the polyurethane resin contains a polyurethane resin having a structure represented by the general formula (I).
<3>
The ink is the ink according to <1> or <2>, which contains a colorant.
<4>
The solid content of the polyurethane resin particles is 3% by mass or more in the ink, and the solid content ratio of the colorant and the polyurethane resin particles is 1.0: (2.0 to 11.0). The ink according to 3>.
<5>
The ink according to <3> or <4>, wherein the colorant is a pigment.
<6>
The ink according to any one of <1> to <5> above, which contains, as the organic solvent, a diol compound and an organic solvent having a solubility parameter (SP value) of 8.9 to 12.0.
<7>
The ink according to any one of the above items <1> to <6>, which has a pH of 8.5 or more.
<8>
The ink according to <7>, wherein the ink contains a strongly basic compound.
<9>
The ink according to <8>, wherein the strongly basic compound is sodium hydroxide or potassium hydroxide.
<10>
The ink according to any one of <1> to <9>, wherein the ink further contains a polyether-modified siloxane compound as a surfactant.
<11>
In a method for producing an ink containing water, an organic solvent and polyurethane resin particles, a step of mixing water, an organic solvent and polyurethane resin particles, and heating the mixture obtained by the above step at 40°C or higher and lower than 70°C for 6 hours or longer The method for producing the ink according to any one of the above items <1> to <10>.
<12>
The ink further contains a colorant, and a step of mixing water, an organic solvent, polyurethane resin particles, and a colorant, and a step of heating the mixture obtained by the step at 40° C. or higher and lower than 70° C. for 6 hours or longer The method for producing an ink according to <11> above.
<13>
A printing method comprising a step of printing by depositing the ink according to any one of the above <1> to <10> on a substrate.
<14>
The step of printing by adhering the ink onto a base material is a step of ejecting the ink from an ink ejection head having a nozzle plate for ejecting the ink and adhering the ink onto the base material,
The ink contains water, an organic solvent, polyurethane resin particles, and a cyclic ester having a structure represented by the following general formula (I), and is stored for one month in a room temperature environment (25±5° C.). The printing method according to <13>, wherein the content of crystals of the cyclic ester having a particle size of 1 μm or more is less than 4 ppm of the entire ink, and the receding contact angle to the nozzle plate is 35° or more.
<15>
A printing apparatus comprising an ink cartridge containing the ink according to any one of the above items <1> to <10>, and an ejection unit that ejects the ink.
<16>
The printing apparatus according to <15>, further including a filter between the ink flow paths from the ink cartridge to the ejection unit that ejects ink.
<17>
The ejection means for ejecting the ink is an ink ejection head having a nozzle plate for ejecting the ink, and the receding contact angle of the ink with respect to the nozzle plate is 35° or more. <15> or <16> Printing device.
<18>
The printing device according to <17>, wherein the nozzle plate has an ink repellent film, and the ink repellent film of the nozzle plate contains a fluorinated acrylate ester polymer.
<19>
In the above <18>, the fluorine-containing acrylate ester polymer contains a polymer obtained by polymerizing at least one of a compound represented by the following general formula (II) and a compound represented by the following general formula (III). The printing device described.
However, in said general formula (II) and (III), X is a hydrogen atom, a C1-C21 linear or branched alkyl group, a halogen atom, CFX1X2 group (however, X1 and X2 are respectively, Independently a hydrogen atom or a halogen atom), a cyano group, a linear or branched fluoroalkyl group having 1 to 21 carbon atoms, a substituted or unsubstituted benzyl group, and a substituted or unsubstituted phenyl R ₁ is an alkyl group having 1 to 18 carbon atoms, R ₂ is an alkylene group having 2 to 6 carbon atoms, and R ₃ is an alkylene group having 2 to 6 carbon atoms. Yes, Y is an acid group, and Rf is a linear or branched fluoroalkyl group having 1 to 21 carbon atoms. m is 1 to 10, n is 2 to 90, p is 1 to 90, and q is 1 to 10.
<20>
In the above <19>, the fluorine-containing acrylate ester polymer contains a polymer having at least one of a structural unit represented by the following general formula (IV) and a structural unit represented by the following general formula (V). The printing device described.
However, in the general formulas (IV) and (V), X represents a hydrogen atom, a linear or branched alkyl group having 1 to 21 carbon atoms, a halogen atom, a CFX1X2 group (provided that X1 and X2 are respectively Independently a hydrogen atom or a halogen atom), a cyano group, a linear or branched fluoroalkyl group having 1 to 21 carbon atoms, a substituted or unsubstituted benzyl group, and a substituted or unsubstituted phenyl R ₁ is an alkyl group having 1 to 18 carbon atoms, R ₂ is an alkylene group having 2 to 6 carbon atoms, and R ₃ is an alkylene group having 2 to 6 carbon atoms. Yes, Y is an acid group, and Rf is a linear or branched fluoroalkyl group having 1 to 21 carbon atoms. m is 1 to 10, n is 2 to 90, p is 1 to 90, and q is 1 to 10.
<21>
The printing device according to any one of <18> to <20>, wherein the ink repellent film contains a polymer having a fluorine-containing heterocyclic structure in its main chain.

(ink)
The ink of the present invention is an ink containing water, an organic solvent and polyurethane resin particles, wherein the ink contains a cyclic ester having a structure represented by the following general formula (I), and the ink is kept in a room temperature environment (25±5° C.). ), the content of crystals of the cyclic ester having a particle size of 1 μm or more is less than 4 ppm in the entire ink after being stored for 1 month.

In particular, non-penetrating media for signage has poor ink fixability, so it is necessary to select the material of the water-dispersible resin particles and increase the addition amount, and further improve the fixability of ink to the film of non-permeable media. Therefore, in many cases, polyurethane resin particles synthesized from a polyol raw material containing an aromatic ring having a structure represented by the following general formula (I) are often used as an ink component.

However, a polyol raw material containing an aromatic ring having a structure represented by the general formula (I) used as a raw material for polyurethane resin particles has a general formula (I) which is difficult to dissolve in water and a water-soluble solvent as a by-product. Since the cyclic ester having the structure shown is contained in the high-viscosity polyol, it becomes polyurethane resin particles in a state where it cannot be removed.
When an ink is produced using the above polyurethane resin particles, and the ink is placed in an ink pack and stored at room temperature (25±5° C.) for 1 month or more, the polyurethane resin particles are represented by the general formula (I). The cyclic ester compound having a structure is eluted, and the cyclic ester crystal having a structure represented by the general formula (I) is precipitated in the ink. It was found that the liquid crystallinity was deteriorated due to the deposition of the cyclic ester crystals in the ink, and the ejection was also unstable.

The cyclic ester having a structure represented by the general formula (I) contained in the ink is considered to include a raw material used for producing a polyurethane resin and a by-product of the raw material. Are listed.
In the structural formula (A), R represents alkylene and is usually an alkylene having 3 to 10 carbon atoms.
Raw materials and by-products that are not removed during the purification or ink production stage will be contained in the ink, and the cyclic ester having the structure represented by the general formula (I) will crystallize in the ink over time. I understood. The inventors of the present invention set the content of crystals having a particle size of 1 μm or more of the cyclic ester having the structure represented by the general formula (I) in the ink to be less than 4 ppm of the total ink, We found that we could achieve the task.
Further, according to the present invention, the fixing property and the drying property are high even for the non-penetrative media for signage and the commercial printing paper, and the image density is high, the liquid permeability and the ejection stability are good, and the storage stability is excellent. Ink can be provided.

The cyclic ester having the structure represented by the general formula (I) is usually insoluble in water. Even when the cyclic ester having the structure represented by the general formula (I) is not confirmed in the water in the water dispersion of the urethane resin particles, the water dispersion of the urethane resin particles, the organic solvent, etc. When the components are mixed to produce an ink, crystals of a cyclic ester having a structure represented by the general formula (I) may be precipitated in the ink. It is presumed that the cyclic ester having the structure represented by the general formula (I) contained in the urethane resin particles is eluted and crystallized when mixed with the organic solvent.

When left standing at room temperature (25±5°C) for 1 month or more, the ink contains 4 ppm or more of crystals of the cyclic ester having a particle size of 1 μm or more. It was found that the above problem occurred and the ejection failure eventually occurred. It was also confirmed that if the crystals of the cyclic ester having a particle size of 1 μm or more were less than 4 ppm of the total ink, there would be no practical problem. Here, “less than 4 ppm of the total ink” means that the content ratio of crystals with respect to the total mass of the ink is less than 0.0004 mass %.
The stationary storage means storage intentionally without giving vibration.
Further, by heating the ink containing the cyclic ester compound having the structure represented by the general formula (I) in the ink at a temperature of 40° C. or higher and lower than 70° C. for 6 hours or longer, the amount of the cyclic ester crystals deposited is reduced. To do. It was also found that the cyclic ester crystals that had precipitated in the ink disappeared.

However, the mechanism by which the amount of cyclic ester crystals deposited and the mechanism by which the cyclic ester crystals disappear are not clear. In the case of heating at 40° C., heating at 40° C. for 2 weeks or more reduces precipitation of the cyclic ester crystals. In the case of heating at 68° C., the cyclic ester crystals are not deposited by heating at 68° C. for 6 hours, and the cyclic ester crystals deposited in the ink also disappear.
The heating time is preferably 2 weeks to 1 month in the case of heating at 40° C., and 6 hours to 12 hours is preferable in the case of heating at 68° C.
Heating at less than 40° C. has no effect of reducing the precipitation of cyclic ester crystals. Also, heating at 70° C. or higher may change the physical properties of the ink or cause ink liquid separation.
Particularly preferably, storage at a temperature of 55° C. to 65° C. for 12 hours to 24 hours has a great effect, and damage to the ink is small.

In the present invention, the precipitated crystals are filtered using a filter paper having a particle retention capacity of 1 μm (for example, filter paper No. 5C for Kiriyama funnel), and the filter paper mass before filtration and the crystals and filter paper mass retained after filtration are The crystals of the cyclic ester having the structure represented by the general formula (I) are quantified by weighing and taking the difference. Therefore, the crystals retained after filtration have a particle size of 1 μm or more, and the number of crystals of the cyclic ester having the structure represented by the general formula (I) having a particle size of 1 μm or more is less than 4 ppm of the entire ink. ..

Although it is presumed that the cyclic ester crystals decrease and disappear, the cyclic ester compound is hydrolyzed by being heated in the presence of a pH adjusting agent (basic compound) contained in the ink. It is considered that a base compound is further added to the ring-opened carboxyl group to form a water-soluble compound, and finally the cyclic ester crystals in the ink are reduced and disappeared.
Due to the above situation, the image quality was improved, and the ink storage stability, liquid permeability, and ejection stability were also improved.

Incidentally, the fact that the ink contains the cyclic ester having the structure represented by the general formula (I) means that crystals precipitated in the ink are separated from the ink, and GC-MS analysis and LC-MS analysis+C ¹³ -NMR+H ^1- It can be qualitatively determined by NMR+FT-IR.

Further, in order to sufficiently secure the wettability of the ink to the non-penetrable media for signage and commercial printing paper, the dynamic surface tension of the ink at a surface life of 15 msec by the maximum bubble pressure method at 25° C. is reduced to 34.0 mN/m or less. It is preferable to keep the static surface tension of the ink at 25° C. at 20.0 mN/m or more.
Due to the above situation, the image quality was improved, and the ink storage stability, liquid permeability, and ejection stability were also improved.

The dynamic surface tension of the ink at a surface life of 15 msec according to the maximum bubble pressure method can be measured at 25° C. using, for example, SITA DynoTester (manufactured by SITA).
The static surface tension of the ink can be measured at 25° C. using, for example, an automatic surface tension meter (DY-300, manufactured by Kyowa Interface Science Co., Ltd.).
By optimizing the balance between the dynamic surface tension and the static surface tension in the ink and setting the receding contact angle of the ink with respect to the nozzle plate to 35° or more, the repulsion of the nozzle plate of the ink ejection head is reduced. The ink film becomes hard to get wet, ejection stability can be ensured, and an extremely stable and ideal printing device in which nozzle omission does not occur in continuous ejection is provided.

The receding contact angle of the ink with respect to the nozzle plate is 35° or more, preferably 35° or more and 80° or less, and more preferably 40° or more and 70° or less.
When the receding contact angle is 35° or more, even if ink adheres to the inner wall surface of the ink chamber of the ink ejection head, it can be easily repelled. The upper limit of the receding contact angle is more difficult to wet as the receding contact angle becomes larger, and therefore is not particularly limited with respect to wettability. It is preferable not to exceed 80° (80° or less).
The receding contact angle can be measured using, for example, an automatic contact angle measuring device_expansion/contraction method.
Examples of the automatic contact angle measuring device include a contact angle meter DMo-501 (manufactured by Kyowa Interface Science Co., Ltd.).
The receding contact angle can be measured, for example, by using the nozzle plate used in the present invention, pushing out 2 μL of ink from the syringe to the outer surface of the nozzle plate, and using the above-mentioned device by the contraction method. The receding contact angle in the present invention means a value at a measurement temperature of 25°C.

The static surface tension B of the ink at 25° C. is preferably 20.0 mN/m or more and 30.0 mN/m or less.
When the static surface tension is 20.0 mN/m or more and 30.0 mN/m or less, the wettability of the ink to the non-penetrative media for ink signage and commercial printing paper can be sufficiently enhanced, and cockling and curling can be prevented. The reduction effect is high, and permeation drying is good even when printing on plain paper.

Next, details of the ink and the method of manufacturing the ink will be described.
<Ink>
-Organic solvent-
The ink of the present invention preferably contains, as an organic solvent, at least one organic solvent having a solubility parameter (SP value) of 8.9 to 12.0 (hereinafter, referred to as “organic solvent X”). As a result, the wettability to the recording medium is improved, and the ink component also permeates into commercial printing paper such as coated paper having a coating layer and having poor ink absorption, and beading can be suppressed. Further, it becomes easy to wet even with a non-penetrating medium.
Further, as described below, the ink of the present invention preferably contains a diol as an organic solvent, but the diol compound may also serve as an organic solvent having a solubility parameter (SP value) of 8.9 to 12.0. As a result, the wettability to the recording medium is improved, and the ink component also permeates into commercial printing paper such as coated paper having a coating layer and having poor ink absorption, and beading can be suppressed. Further, it becomes easy to wet even with a non-penetrating medium.

An organic solvent having an SP value of 8.9 or higher is generally suitable for a water-based ink such as the present invention because it has high solubility in water and hardly separates. Further, an organic solvent having an SP value of 12.0 or less improves the drying property and beading.
The SP value is a value defined by the regular solution theory introduced by Hildebrand and serves as a measure of the solubility of the binary solution. Further, the SP value in the present invention is a value calculated by the Fedors method. It is represented by the square root of the cohesive energy density in the regular solution theory, and the unit is (J/cm ³ ) ^0.5 . It can be calculated with simple software that is widely used.

The organic solvent X is preferably water-soluble, and particularly preferably an amide compound represented by the following general formula (VI) or an oxetane compound represented by the general formula (VII).

(In the formula, R represents an alkyl group having 1 to 6 carbon atoms.)

(In the formula, R ₁ represents an alkyl group having 1 to 2 carbon atoms.)

Examples of the amide compound represented by the general formula (VI) include compounds of the following formulas (1) to (4).

In addition, examples of the oxetane compound represented by the general formula (VII) include compounds of the following formulas (5) to (6).

The content of the organic solvent X is preferably 3% by mass or more, and more preferably 5 to 20% by mass of the entire ink. When the content is 5% by mass or more, the ink component permeates the commercial printing paper, beading can be suppressed, and the effect of making the non-penetrable medium wet easily can be obtained. If the content is 20% by mass or less, the ejection stability will not deteriorate due to the increase in the viscosity of the ink.

Further, in the present invention, the organic solvent contains a glycol ether compound (compound Z) having a vapor pressure of 50 mmHg or more in an environment of 100° C., so that the drying property is improved and the drying property is improved even on commercial printing paper. It becomes possible. In addition, even if the image portion comes into contact with the transport roller immediately after drying with warm air at 100° C., the image is not transferred, and high-speed productivity is secured.
The compound Z is preferably one that dissolves in high-purity water. Examples thereof include propylene glycol monopropyl ether (bp 150° C., vapor pressure 107 mmHg), propylene glycol monoethyl ether (bp 133° C., vapor pressure 252 mmHg), propylene glycol monomethyl ether (bp 120° C., vapor pressure 360 mmHg), propylene glycol monobutyl ether. (Bp 170° C., vapor pressure 59 mmHg), 3-methoxy-1-butanol (bp 161° C., vapor pressure 76 mmHg), 3-methoxy-3-methyl-1-butanol (bp 174° C., vapor pressure 50 mmHg).

The content ratio (mass ratio) of the organic solvent X and the compound Z in the ink is preferably 1:1 to 8:1. It is more preferably 3:1 to 5:1. When this ratio is 1:1 or more, that is, when the amount of the organic solvent X is larger than that of the compound Z, the drying property does not become too good, and the inside of the inkjet head is also dried, which causes a problem in ejection stability. Never. On the other hand, when the ratio is 8:1 or less, the amount of the organic solvent X is not too large, the drying property on the commercial printing paper is improved, and the productivity is improved.
The total content of the organic solvent in the ink containing the organic solvent X and the compound Z is preferably 5 to 30 mass% of the entire ink. When it is 5% by mass or more, the beading suppressing effect on commercial printing paper is not reduced. Further, when the content is 30% by mass or less, the ink viscosity is not significantly increased, and there is no problem in ejection stability.

Further, in view of ejection stability and ink storage stability, it is preferable to contain polyhydric alcohols as the organic solvent. Specifically, diethylene glycol (bp 245° C.), triethylene glycol (bp 285° C.), tetraethylene glycol (bp 324 to 330° C.), 1,3-butanediol (bp 203 to 204° C.), glycerin (bp 290° C.), diglycerin (Bp270° C./20 hPa), 1,2,3-butanetriol (bp175° C./33 hPa), 1,2,4-butanetriol (bp 190-191° C./24 hPa,) dipropylene glycol (bp232° C.), 1,5 -Pentanediol (bp242°C), propylene glycol (bp187°C), 2-methyl-2,4-pentanediol (bp197°C), ethylene glycol (bp196-198°C), tripropylene glycol (bp267°C), hexylene glycol (Bp 197° C.), polyethylene glycol (viscous liquid to solid), 1,6-hexanediol (bp 253 to 260° C.), 1,2,6-hexanetriol (bp 178° C.), trimethylolethane (solid, mp 199 to 201) C.), trimethylolpropane (solid, mp 61.degree. C.) and the like.

The organic solvent preferably contains at least one non-wetting agent polyol compound or glycol ether compound having 8 to 11 carbon atoms. The polyol compound preferably contains a diol compound. Here, non-wetting agent property means having a solubility between 0.2 and 5.0 mass% in water at 25°C. Among these compounds, a 1,3-diol compound represented by the following general formula (VIII) is preferable, and 2-ethyl-1,3-hexanediol [solubility: 4.2% (25° C.)], 2, 2,4-trimethyl-1,3-pentanediol [solubility: 2.0% (25° C.)] is particularly preferable.
(In the above formula, R'is a methyl group or an ethyl group, R" is hydrogen or a methyl group, and R'" is an ethyl group or a propyl group.)

Examples of other non-wetting agent polyol compounds include 2-ethyl-2-methyl-1,3-propanediol, 3,3-dimethyl-1,2-butanediol, and 2,2-diethyl-1,3. -Propanediol, 2-methyl-2-propyl-1,3-propanediol, 2,4-dimethyl-2,4-pentanediol, 2,5-dimethyl-2,5-hexanediol, 5-hexene-1 And aliphatic diols such as 2-diol.
The content of the non-wetting agent polyol compound having 8 to 11 carbon atoms and the glycol ether compound in the ink is preferably 0.5 to 4% by mass, and more preferably 1 to 3% by mass. When it is 0.5% by mass or more, the ink penetrating effect is obtained and the image quality is improved. Further, when the content is 4% by mass or less, the ink is sufficiently dissolved in the ink, and problems such as separation and increase in initial viscosity of the ink do not occur.

-Water-dispersible resin particles-
As the water-dispersible resin particles, those having excellent film-forming property (image forming property), solvent resistance, high water resistance, and high weather resistance have high water resistance and high image density (high color development). It is useful for image recording, and examples thereof include condensation type synthetic resins, addition type synthetic resins, and natural polymer compounds. In the present invention, the polyurethane resin particles are contained.
Further, since the non-penetrable media for signage has poor ink fixability, it is necessary to select the material of the water-dispersible resin particles and increase the amount of addition. Further, in order to improve the fixing property to a film of non-penetrable media, polyurethane resin particles synthesized from a polyol raw material containing an aromatic ring having a structure represented by the general formula (I) are often used.

Examples of the polyol raw material containing an aromatic ring having the structure represented by the general formula (I) include terephthalic acid and isophthalic acid. When terephthalic acid or isophthalic acid is used as a raw material, a cyclic ester compound is produced. It has been confirmed by GC-MS that a cyclic ester in which two types of phthalic acid are mixed is produced when the above two types of raw materials are used.
In the present invention, the polyurethane resin particles use a polyol raw material containing an aromatic ring having a structure represented by the general formula (I) as a raw material of the polyurethane resin particles, and have a structure represented by the general formula (I). It is preferable to contain particles.
The proportion of the polyol raw material containing the aromatic ring having the structure represented by the general formula (I) in the polyurethane resin particles having the structure represented by the general formula (I) is about half of that in the polyol, and the polyurethane is It is preferably about 10 to 30% of the resin. When the ratio of the polyol raw material is within the above range, the alcohol resistance is excellent.
The preferred range of the content of the polyurethane resin particles having the structure represented by the general formula (I) is 2.0 to 20.0% by mass, more preferably 2.8 to 15.0% by mass in terms of resin solid content. Is.

Examples of the other condensed synthetic resin include polyester resin, polyurethane resin, polyepoxy resin, polyamide resin, polyether resin, poly(meth)acrylic resin, acryl-silicone resin, and fluorine resin. Examples of the addition synthetic resin include polyolefin resins, polystyrene resins, polyvinyl alcohol resins, polyvinyl ester resins, polyacrylic acid resins, unsaturated carboxylic acid resins, and the like. Examples of the natural polymer compound include celluloses, rosins, and natural rubber.
Among these, polyurethane resin fine particles are preferable in consideration of the ink fixability. Moreover, you may use together 2 or more types of the said water-dispersible resin.

As the water-dispersible resin, it is possible to use a resin which has a hydrophilic group and has self-dispersibility, or a resin which does not have a dispersibility and which has been made dispersible by a surfactant or a resin having a hydrophilic group. Among these, an ionomer of a polyester resin or a polyurethane resin or an emulsion of resin particles obtained by emulsion polymerization and suspension polymerization of an unsaturated monomer is most suitable.
In the case of emulsion polymerization of unsaturated monomers, unsaturated monomers, polymerization initiators, surfactants, chain transfer agents, chelating agents, and a resin emulsion by reacting in water added with a pH adjusting agent and the like. As a result, the water-dispersible resin can be easily obtained, the resin constitution can be easily changed, and desired properties can be easily produced.

The pH of the water-dispersible resin is preferably 4 to 12 because molecular chain breakage such as dispersion breakage or hydrolysis is caused under strong alkaline or strong acidity, and particularly from the viewpoint of miscibility with the water-dispersible colorant. , 7-11 are more preferable, and 8-10.5 are still more preferable.

Further, the water-dispersible resin has a function of fixing the water-dispersible colorant on the medium, and has a function of forming a film at room temperature or higher to improve the fixability of the colorant. Therefore, the minimum film-forming temperature (MFT) of the water-dispersible resin is preferably 100°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 the printed matter becomes tacky. Therefore, the glass transition temperature is preferably -30°C or higher.
The content of the water-dispersible resin in the ink is preferably 0.5 to 20% by mass, and more preferably 1 to 15% by mass in terms of solid content.
However, when the base material fixability of the colorant to non-penetrating media for signage or commercial printing paper is sufficiently taken into consideration, the ink contains polyurethane resin particles in a solid content of 3% by mass or more, and the colorant and polyurethane resin are contained. The solid content ratio with the particles is preferably 1.0: (2.0 to 12.0), and particularly preferably 1.0: (2.0 to 11.0). The content of the polyurethane resin particles is the total amount of the polyurethane resin particles that are solids contained in the ink.

-Colorant-
The ink of the present invention can be a clear ink containing no colorant, but can also be an ink containing a colorant. The colorant is preferably a pigment.
As the colorant, a surfactant-dispersed pigment in which a pigment is dispersed with a surfactant, a resin-dispersed pigment in which a pigment is dispersed with a resin, a resin-coated dispersed pigment in which the surface of the pigment is coated with a resin, and a hydrophilic group are provided on the pigment surface Although there are self-dispersion pigments and the like, water-dispersible pigments are preferable. Among them, the resin-coated pigment or the self-dispersion pigment, which has at least one hydrophilic group on the pigment surface, is preferable.
Such hydrophilic _{groups, -COOM, -SO 3 M, -PO} 3 HM, -PO 3 M 2, -CONM 2, -SO 3 NM 2, -NH-C 6 H 4 -COOM, -NH- _{C 6 H 4 -SO 3 M,} -NH-C 6 H 4 -PO 3 HM, -NH-C 6 H 4 -PO 3 M 2, -NH-C 6 H 4 -CONM 2, -NH-C 6 H ₄ -SO ₃ NM ₂ and the like. These hydrophilic groups can be introduced by a known method.

The counter ion M in the hydrophilic group is preferably a quaternary ammonium ion. Specific examples thereof include tetramethylammonium ion, tetraethylammonium ion, tetrapropylammonium ion, tetrabutylammonium ion, tetrapentylammonium ion, benzyltrimethylammonium ion, benzyltriethylammonium ion and tetrahexylammonium ion, and tetraethylammonium ion. Ions, tetrabutylammonium ion and benzyltrimethylammonium ion are preferred, and tetrabutylammonium ion is particularly preferred.
The ink using the above pigment has particularly high storage stability over time, and suppresses an increase in viscosity upon evaporation of water. It is presumed that this is because the hydrophilic group having a quaternary ammonium ion can keep the dispersion of the pigment stable even when water is evaporated from the water-rich ink to become rich in the organic solvent.

As a colorant other than the pigment having a hydrophilic group, a polymer emulsion in which pigment is contained in polymer fine particles is preferable. The pigment may be encapsulated in the polymer particles or may be adsorbed on the surface of the polymer particles. In this case, it is not necessary for all the pigments to be encapsulated or adsorbed, and some may be dispersed in the emulsion. Examples of the polymer for polymer particles include vinyl-based polymers, polyester-based polymers, polyurethane-based polymers and the like, but vinyl-based polymers and polyester-based polymers are particularly preferable.
Specific examples thereof include those disclosed in JP 2000-53897 A and JP 2001-139849 A.

Further, a general organic pigment, or a composite pigment in which particles of an inorganic pigment are coated with an organic pigment or carbon black can also be used. The composite pigment can be produced by a method of depositing an organic pigment in the presence of particles of an inorganic pigment, a mechanochemical method of mechanically mixing and grinding an inorganic pigment and an organic pigment, or the like. If necessary, a layer of an organosilane compound produced from polysiloxane or alkylsilane may be provided between the inorganic pigment and the organic pigment to improve the adhesiveness between them.
The mass ratio of the inorganic pigment particles to the organic pigment of the coloring material or carbon black is preferably 3:1 to 1:3, more preferably 3:2 to 1:2. When the amount of the coloring material is within the above range, the coloring property and the coloring power are not lowered, and the transparency and the color tone are not deteriorated.
As the composite pigment, silica/carbon black composite material, silica/phthalocyanine PB15:3 composite material, silica/disazo yellow composite material, silica/quinacridone PR122 composite material and the like manufactured by Toda Kogyo Co., Ltd. have a small primary average particle size. It is suitable.

Here, when the inorganic pigment particles having a primary particle diameter of 20 nm are coated with an equal amount of the organic pigment, the primary particle diameter of the pigment is about 25 nm. If a suitable dispersant can be used to disperse the primary particles, an extremely fine pigment-dispersed ink having a dispersed particle diameter of 25 nm can be prepared. In the composite pigment, not only the organic pigment on the surface contributes to the dispersion but also the properties of the inorganic pigment at the center appear through a thin layer of the organic pigment having a thickness of about 2.5 nm, so that both can be dispersed and stabilized at the same time. The choice of pigment dispersant is also important.

Examples of the inorganic pigment include titanium oxide, iron oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, cadmium red, chrome yellow, and carbon black. Among these, carbon black is particularly preferable, and examples thereof include channel black, furnace black, gas black and lamp black produced by known methods such as a contact method, a furnace method and a thermal method.

Examples of the organic pigment include azo pigments, polycyclic pigments, dye chelates, nitro pigments, nitroso pigments, and aniline black. Among these, azo pigments and polycyclic pigments are preferable. Examples of the azo pigment include azo lake, insoluble azo pigment, condensed azo pigment, and chelate azo pigment. Examples of the polycyclic pigments include phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, indigo pigments, thioindigo pigments, isoindolinone pigments, and quinofuraron pigments. Examples of the dye chelates include basic dye chelates and acid dye chelates.

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

The BET specific surface area of the pigment used is preferably about 10 to about 1500 m ² /g, more preferably about 20 to about 600 m ² /g, still more preferably about 50 to about 300 m ² /g.
If it is not easy to use the one with the desired specific surface area, a general size reduction or grinding treatment (for example, ball milling, jet milling, ultrasonic treatment) is performed in order to make the pigment have a relatively small particle size. I'm fine.
The median diameter (D50) of the water-dispersible colorant is preferably 10 to 200 nm in the ink.
The content of the water-dispersible colorant in the ink is preferably 1 to 15% by mass, and more preferably 1.5 to 10% by mass in terms of solid content. When the content is 1% by mass or more, the color developability and the image density of the ink are improved, and when the content is 15% by mass or less, the viscosity of the ink is not increased and the ejection property is not deteriorated, and further economically. preferable.
In the present invention, a dye may be used in combination for the purpose of adjusting the color tone, but it is necessary to use it within a range that does not deteriorate the weather resistance.

-Surfactant-
In the present invention, it is preferable to use a polyether-modified siloxane compound as the surfactant. As a result, the ink becomes hard to wet the head nozzle plate ink-repellent layer, and it is possible to prevent ejection failure due to ink adhesion to the nozzle and improve ejection stability. In addition, the ink does not easily adhere to the nozzle ink repellent layer surface, which is particularly problematic, and the ejection failure does not easily occur.
Among them, those represented by the following general formula (IX) to general formula (XII) are preferable, particularly, the dispersion stability is not impaired by the combination of the type of the water-dispersible colorant and the organic solvent, and the dynamic surface tension is low, Those having high penetrability and leveling properties are preferable.
These surfactants may be used alone or in combination of two or more.

(In the above formula, R represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, m is an integer of 0 to 23, n is an integer of 1 to 10, a is an integer of 1 to 23, and b is 0. Represents the integer of 23.)

Examples of the compound represented by the general formula (IX) include compounds represented by the following formulas (7) to (14).

(In the above formula, R ₂ and R ₃ represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, m represents an integer of 1 to 8, and c and d represent an integer of 1 to 10.)

Examples of the compound represented by the general formula (X) include the compounds of the following formula (15).

(In the above formula, R ₄ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and e represents an integer of 1 to 8.)

Examples of the compound represented by the general formula (XI) include the compound of the following formula (16).

[In said formula, R< ₅ > represents the polyether group of following General formula (A), f represents the integer of 1-8. ]

(In the above formula, R ₆ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, g represents an integer of 0 to 23, and h represents an integer of 0 to 23, provided that g and h are 0 at the same time. Excluding cases.)

Examples of the compound represented by the general formula (XII) include the compounds of the following formulas (17) to (19).

Further, as commercially available polyether-modified siloxane compound surfactants showing the same effect as the above compounds, TORAY Dow Corning's 71ADDITIVE, 74ADDITIVE, 57ADDITIVE, 8029ADDITIVE, 8054ADDITIVE, 8211ADDITIVE, 8019ADDITIVE, 8526ADDITIVE, 2123, FZ-2191, TSF4440, TSF4441, TSF4445, TSF4446, TSF4450, TSF4452, TSF4460, manufactured by Momentive Performance Materials, Inc., Silface SAG002, Silface SAG003, Silface SAG005, manufactured by Nissin Chemical Industry Co. Silface SAG503A, Silface SAG008, Silface SJM003, and Evonik's TEGO_Wet_KL245, TEGO_Wet_250, TEGO_Wet_260, TEGO_Wet_265, TEGO_Wet_270, TEGO_WET-3, BYOBYK-45K, BBYKY, BBYKMY Japan. 375, BYK-377 and the like.

If necessary, the above polyether-modified siloxane compound surfactant may be used in combination with a fluorine-based surfactant, a silicone-based surfactant, an acetylene glycol or an acetylene alcohol-based surfactant.
The content of the surfactant in the ink is preferably 0.001 to 5 mass%, more preferably 0.5 to 3 mass%. If it is 0.001% by mass or more, the effect of adding the surfactant can be obtained.
However, if the amount exceeds 5 mass, the effect of addition will be saturated, so there is no point in increasing the amount.

-Other ingredients-
In addition to the components described above, various known additives may be added to the ink of the present invention, if necessary. Examples thereof include penetrants, foam suppressors (foam inhibitors), pH adjusters, antiseptic and antifungal agents, chelating agents, rust preventives, antioxidants, ultraviolet absorbers, oxygen absorbers, and light stabilizers. Are listed.

-Foam suppressor-
The foam suppressor is used to suppress the foaming by adding a very small amount to the ink.
Here, foaming means that a liquid forms a thin film and wraps air. Characteristics such as surface tension and viscosity of the ink are involved in the generation of the bubbles. That is, a liquid having a high surface tension, such as water, is hard to foam because the force that tries to reduce the surface area of the liquid acts as much as possible. On the other hand, a high-viscosity, high-permeability ink is apt to foam due to its low surface tension, and bubbles generated due to the viscosity of the solution are easily maintained and are difficult to defoam.

Usually, the foam suppressor locally lowers the surface tension of the foam film to destroy the foam, or the foam suppressor which is insoluble in the foaming liquid is scattered on the surface of the foaming liquid to break the foam. When a polyether-modified siloxane compound surfactant, which has an extremely strong function of lowering the surface tension as a surfactant, is used in the ink, the surface tension of the foam film is locally reduced even if a foam suppressor by the former mechanism is used. Cannot be lowered. Therefore, the latter foam suppressor which is insoluble in the foaming liquid is used, but in this case, the stability of the ink is lowered by the foam suppressor which is insoluble in the solution.
On the other hand, the foam suppressor represented by the following general formula (XIII) does not have the action of lowering the surface tension as strongly as the polyether-modified siloxane compound surfactant, but has high compatibility with the surfactant. Therefore, it is considered that the foam suppressor is efficiently taken into the foam film, and the surface of the foam film is locally imbalanced due to the difference in surface tension between the surfactant and the foam suppressor, and the foam is destroyed. To be

(In the above formula, R ₇ and R ₈ each independently represent an alkyl group having 3 to 6 carbon atoms, and R ₉ and R ₁₀ each independently represent an alkyl group having 1 to 2 carbon atoms; Represents an integer of 1 to 6.)

Preferred examples of the compound represented by the general formula (XIII) include 2,4,7,9-tetramethyldecane-4,7-diol and 2,5,8,11-tetramethyldodecane-5,8. -Diols. 2,5,8,11-Tetramethyldodecane-5,8-diol is particularly preferable because of its foam-suppressing effect and high compatibility with ink.
The content of the foam suppressor in the ink is preferably 0.01 to 10% by mass, more preferably 0.1 to 5% by mass. When the content is 0.01% by mass, the foam suppressing effect is obtained, and when the content is 10% by mass or less, the foam suppressing effect reaches a peak or the ink physical properties such as viscosity and particle size are adversely affected. There is no such thing.

-PH adjuster-
The pH adjuster is not particularly limited as long as it can adjust the pH to 7 to 11 without adversely affecting the prepared ink, and can be appropriately selected according to the purpose.
Examples thereof include alcohol amines, hydroxides of alkali metal elements, hydroxides of ammonium, phosphonium hydroxides, carbonates of alkali metals, and the like.
When the pH is out of the range of 7 to 11, a large amount of the inkjet head or the ink supply unit is melted out, which may cause problems such as deterioration or leakage of ink and ejection failure.
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 and quaternary ammonium hydroxide.
Examples of the phosphonium hydroxide include quaternary phosphonium hydroxide.
Examples of the alkali metal carbonate include lithium carbonate, sodium carbonate, potassium carbonate and the like.
A strongly basic compound is preferably used as the pH adjuster.

By including a strongly basic compound in the ink, it is possible to suppress the precipitation of crystals of the cyclic ester having the structure represented by the general formula (I). As a result, the fixability of the ink can be improved, and the liquid permeability can be improved. Even when the ink is ejected by the inkjet method, non-ejection can be avoided and stable printing can be performed.
It is presumed that a strong base compound acts on the cyclic ester compound having the structure represented by the general formula (I) to cause hydrolysis, and an effect of suppressing crystal precipitation is obtained.
The strong base compound is not particularly limited, but sodium hydroxide or potassium hydroxide is preferably used from the viewpoint of effectively suppressing crystallization.
The content of the strong base compound contained in the ink is preferably 0.05% by mass or more and 0.24% by mass or less from the viewpoint of effectively suppressing crystallization.
It is also preferable to use 2-amino-2-ethyl-1,3 propanediol as the pH adjuster.

− Antiseptic/antifungal agent−
Examples of the antiseptic/antifungal agent include sodium dehydroacetate, sodium sorbate, sodium 2-pyridinethiol-1-oxide, sodium benzoate, sodium pentachlorophenol, and the like.

-Chelating reagent-
Examples of the chelating agent include sodium ethylenediaminetetraacetate, sodium nitrilotriacetate, sodium hydroxyethylethylenediaminetriacetate, sodium diethylenetriaminepentaacetate, and sodium uramildiacetate.

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

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

-UV absorber-
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.

-Manufacture of ink-
The ink of the present invention comprises a step of dispersing or dissolving water, an organic solvent, a polyurethane resin particle and a colorant optionally added, and other components in an aqueous medium, and further stirring and mixing them as necessary. The mixture obtained in the above step can be produced by heating the mixture at 40° C. or higher and lower than 70° C. for 6 hours or longer. 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 a normal stirring blade, a magnetic stirrer, a high speed disperser, etc. be able to.

-Ink physical properties-
The physical properties of the ink of the present invention are not particularly limited and can be appropriately selected according to the purpose.
However, if the static surface tension of the ink is 20 mN/m or more and the dynamic surface tension is 34 mN/m or less when the bubble lifetime is 15 msec according to the maximum bubble pressure method, sufficient wettability with respect to the recording medium is obtained. Although it can be ensured, the nozzle plate of the inkjet head is less likely to get wet with the OPTOOL water repellent film, and ejection stability can be ensured, which is an extremely stable ink, which is preferable.
The viscosity of the ink at 25°C is preferably 5 to 25 mPa·s, more preferably 6 to 20 mPa·s. If it is 5 mPa·s or more, the effect of improving the printing density and character quality can be obtained.
Further, if it is 25 mPa·s or less, the ink ejection property can be secured.
The above-mentioned viscosity can be measured at 25°C using, for example, a viscometer (RE-85L, manufactured by Toki Sangyo Co., Ltd.).
Further, in order to secure the storage stability of the ink, a pH of 8 to 11 is preferable, and a pH of 8.5 to 11 is more preferable.

The ink of the present invention is used as an ink jet head to change the internal volume of an ink flow path by deforming a vibrating plate forming a wall surface of the ink flow path by using a piezoelectric element as a pressure generating means for pressurizing the ink in the ink flow path. So-called piezo type (see Japanese Patent Application Laid-Open No. 2-51734), or so-called thermal type in which ink is heated in an ink flow path by using a heating resistor to generate bubbles ( Japanese Patent Laid-Open No. 61-59911), a diaphragm forming a wall surface of an ink flow path and an electrode are arranged so as to face each other, and the diaphragm is deformed by an electrostatic force generated between the diaphragm and the electrode. It can be favorably used in a printer equipped with any ink jet head such as an electrostatic type (see Japanese Patent Laid-Open No. 6-71882) that changes the volume of the ink flow path to eject ink droplets.
Further, the ink of the present invention may be used by being contained in a container such as an ink cartridge.

<Recording medium>
The recording medium capable of recording using the ink of the present invention is not particularly limited and may be appropriately selected depending on the purpose. Examples thereof include plain paper, glossy paper, special paper, cloth, film and OHP. Examples include sheets and general-purpose printing paper. However, the ink of the present invention is very excellent in that it can perform good printing on non-penetrating media for signage and commercial printing paper as well as other papers.
A printed matter having an image formed using the ink of the present invention has a high image quality, has no bleeding, is excellent in stability over time, and can be suitably used for various purposes as a material in which various prints or images are recorded. it can.

Next, the ink ejection head will be described.
<Ink ejection head>
The ink discharge head has a nozzle plate, and further has other members as necessary.

-Nozzle plate-
The nozzle plate has a nozzle substrate and an ink repellent film on the nozzle substrate.

-Nozzle substrate-
Nozzle holes are provided in the nozzle substrate, and the number, shape, size, material, structure, etc. are not particularly limited and can be appropriately selected according to the purpose.
The nozzle substrate has a surface on the ink ejection side from which ink is ejected from the nozzle hole, and a liquid chamber bonding surface located on the opposite side of the surface on the ink ejection side.
The ink repellent film is formed on the surface of the nozzle substrate on the ink ejection side.

The planar shape of the nozzle substrate is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include a rectangle, a square, a rhombus, a circle and an ellipse. Moreover, examples of the cross-sectional shape of the nozzle substrate include a flat plate shape and a plate shape.
The size of the nozzle substrate is not particularly limited and can be appropriately selected according to the size of the nozzle plate.

The material of the nozzle substrate is not particularly limited and may be appropriately selected depending on the purpose. Examples thereof include stainless steel, Al, Bi, Cr, InSn, ITO, Nb, Nb ₂ O ₅ , NiCr and Si. _{SiO2, Sn, Ta 2 O 5} , Ti, W, ZAO (ZnO + Al 2 O 3), Zn and the like. These may be used alone or in combination of two or more. Among these, stainless steel is preferable from the viewpoint of rust resistance.

The stainless steel is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include austenitic stainless steel, ferritic stainless steel, martensitic stainless steel, and precipitation hardening stainless steel. These may be used alone or in combination of two or more.

At least the surface of the nozzle substrate on the ink ejection side may be subjected to oxygen plasma treatment to introduce a hydroxyl group from the viewpoint of improving the adhesion between the ink repellent film and the nozzle substrate.

-Nozzle hole-
The number, arrangement, spacing, opening shape, opening size, sectional shape of the openings, etc. of the nozzle holes are not particularly limited and can be appropriately selected according to the purpose.
The arrangement of the nozzle holes is not particularly limited and may be appropriately selected depending on the purpose. For example, the plurality of nozzle holes are arranged at equal intervals along the length direction of the nozzle substrate. The aspect etc. which have been mentioned.
The arrangement of the nozzle holes can be appropriately selected according to the type of ink to be ejected, but is preferably one row to a plurality of rows, more preferably one row to four rows.
The number of nozzle holes per row is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 10 or more and 10,000 or less, more preferably 50 or more and 500 or less.
The interval (pitch) P, which is the shortest distance between the centers of the adjacent nozzle holes, is not particularly limited and can be appropriately selected according to the purpose, but is preferably 21 μm or more and 169 μm or less.
The opening shape of the nozzle hole is not particularly limited and may be appropriately selected depending on the purpose, and examples thereof include a circle, an ellipse, and a quadrangle. Among these, the circular shape is preferable from the viewpoint of ejecting ink droplets.

-Ink repellent film-
The ink repellent film preferably contains a fluorinated acrylate ester polymer or a polymer having a fluorinated heterocyclic structure in its main chain.
When the ink repellent film contains the fluorine-containing acrylate ester polymer or the polymer having a fluorine-containing heterocyclic structure in the main chain, the surface free energy becomes very small, and the ink having low surface tension used in the present invention Even if it is, it is preferable because it is possible to maintain a state in which it is difficult to get wet. However, when another material is used as the ink repellent film, the surface free energy becomes extremely small, and the ink having low surface tension used in the present invention may be wet.

---Fluorine-containing acrylate ester polymer---
The fluorinated acrylate ester polymer preferably contains at least one of the compound represented by the following general formula (II) and the compound represented by the following general formula (III) as a monomer unit.
However, in said general formula (II) and (III), X is a hydrogen atom, a C1-C21 linear or branched alkyl group, a halogen atom, CFX1X2 group (however, X1 and X2 are respectively, Independently a hydrogen atom or a halogen atom), a cyano group, a linear or branched fluoroalkyl group having 1 to 21 carbon atoms, a substituted or unsubstituted benzyl group, and a substituted or unsubstituted phenyl R ₁ is an alkyl group having 1 to 18 carbon atoms, R ₂ is an alkylene group having 2 to 6 carbon atoms, and R ₃ is an alkylene group having 2 to 6 carbon atoms. Yes, Y is an acid group, and Rf is a linear or branched fluoroalkyl group having 1 to 21 carbon atoms. m is 1 to 10, n is 2 to 90, p is 1 to 90, and q is 1 to 10.
Further, the polymer obtained by polymerizing at least one of the compounds represented by the general formula (II) and the general formula (III) is a structural unit represented by the general formula (IV) and the general formula (V ) It becomes a polymer which has at least one of the structural units represented by.

The R ₁ preferably has 1 to 18 carbon atoms, more preferably 1 to 4 carbon atoms, and examples thereof include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, and a nonyl group. Group, decyl group, undecyl group and the like.
R ₂ is an alkylene group having 2 to 6 carbon atoms, and examples thereof include an ethylene group, a propylene group, and a butylene group. Among these, ethylene group is preferable.
R ₃ is an alkylene group having 2 to 6 carbon atoms, and examples thereof include an ethylene group, a propylene group, and a butylene group. Among these, ethylene group is preferable.
The Y is an acid group, and examples thereof include a sulfonic acid group, a succinic acid group, an acetic acid group, a phthalic acid group, a hydrogenated phthalic acid group, and a maleic acid group.

The Rf is a linear or branched fluoroalkyl group having 1 to 21 carbon atoms, preferably a perfluoroalkyl group, and the carbon number of Rf is more preferably 1 to 10.
Examples of the Rf, for _{example, -CF 3, -CF 2 CF 3} , -CF 2 CF 2 CF 3, -CF (CF 3) 2, -CF 2 CF 2 CF 2 CF 3, -CF 2 CF (CF 3 _{) 2, -C (CF 3)} 3, - (CF 2) 4CF 3, - (CF 2) 2 CF (CF 3) 2, -CF 2 C (CF 3) 3, -CF (CF 3) CF 2 _{CF 2 CF 3, - (CF} 2) 5 CF 3, - (CF 2) 3 CF (CF 3) 2, - (CF2) 4 CF (CF 3) 2, - (CF 2) 7 CF 3, - ( _{CF 2) 5 CF (CF 3} ) 2, - (CF 2) 6 CF (CF 3) 2, - (CF 2) such as 9 CF ₃ and the like.

1-10 are preferable and, as for said m, 1-3 are more preferable.
2-90 are preferable, as for said n, 3-50 are more preferable, and 4-30 are still more preferable. 1-90 are preferable and, as for said p, 1-30 are more preferable.
1-10 are preferable and, as for said q, 1-3 are more preferable.

As the fluorinated acrylate ester polymer, those synthesized as appropriate may be used, or commercially available products may be used.
The fluorine-containing acrylate ester polymer (Rf is C ₆ F ₁₃ ) represented by the general formula (III) can be synthesized, for example, by the following reaction formula.

The fluorine-containing acrylate ester polymer (Rf is C ₆ F ₁₃ ) represented by the general formula (III) can be synthesized, for example, by the following reaction formula.

From the viewpoint of ink repellency (contact angle), the content of fluorine in the fluorinated acrylate ester polymer is preferably 10% by mass or more, more preferably 25% by mass or more, and further preferably 50% by mass or more.
Examples of the commercially available product include krytox FSL (manufactured by DuPont), krytox FSH (manufactured by DuPont), FomblinZ (manufactured by Solvay Solexis), FLUOROLINKS10 (manufactured by Solvay Solexis), Optool DSX (manufactured by Daikin Industries, Ltd.), FLUOROLINK C10 (manufactured by Solvay Solexis), morescophosphalor A20H (manufactured by Matsumura Oil Research Co., Ltd.), morescofosphalol ADOH (manufactured by Matsumura Oil Research Co., Ltd.), morescophosphalor DDOH (stock) Matsumura Oil Research Institute), Fluorosurf FG5010 (manufactured by Fluorotechnology), Fluorosurf FG5020 (manufactured by Fluorotechnology), Fluorosurf FG5060 (manufactured by Fluorotechnology), Fluorosurf FG5070 (manufactured by Fluorotechnology) and the like.

The ink repellent film is composed of a compound film containing the fluorine-containing acrylate ester polymer skeleton in its molecule. An inorganic oxide layer is provided between the nozzle substrate and the ink repellent film in order to improve the adhesiveness by allowing a large number of hydroxyl groups as bonding points with a compound containing a fluorinated acrylate ester polymer skeleton to exist in the molecule. You can also
Examples of the material of the inorganic oxide layer include SiO ₂ and TiO ₂ .
The average thickness of the inorganic oxide layer is preferably 0.001 μm or more and 0.2 μm or less, and more preferably 0.01 μm or more and 0.1 μm or less.

Examples of the compound containing the fluorine-containing acrylate ester polymer skeleton in the molecule include low-molecular substances and resins.
Examples of the compound containing the fluorine-containing acrylate ester polymer skeleton in the molecule include, for example, JP-B-3-43065, JP-A-6-210857, JP-A-10-32984, and JP-A-2000-94567. , JP-A-2002-145645, JP-A-2003-341070, JP-A-2007-106024, JP-A-2007-125849, and the like.
As a particularly preferable example, modified perfluoropolyoxetane (manufactured by Daikin Industries, Ltd., Optool DSX) can be exemplified.
The average thickness of the ink repellent film is preferably 0.001 μm or more and 0.2 μm or less, and more preferably 0.01 μm or more and 0.1 μm or less.

Examples of the method for forming the ink repellent film using the compound containing the fluorinated acrylate ester polymer skeleton in the molecule include spin coating using a fluorine-based solvent, roll coating, coating such as dipping, printing, vacuum deposition and the like. To be
Examples of the fluorine-based solvent include Novec (manufactured by 3M Co., Ltd.), Bertrel (manufactured by DuPont), and Galden (manufactured by Solvay Solexis).

---Polymer having a fluorine-containing heterocyclic structure in the main chain---
As the polymer having a fluorine-containing heterocyclic structure in the main chain, it is particularly preferable to use an amorphous polymer among the fluorine-containing polymers having a heterocyclic structure. Since the amorphous polymer is excellent in film strength, adhesion to a substrate, film uniformity, etc., the effects of the present invention can be further exerted.
Examples of the polymer having a fluorine-containing heterocyclic structure in the main chain include, for example, US Pat. No. 3,418,302, US Pat. No. 3,978,030, and JP-A-63-238111. Polymers described in JP-A-63-238115, JP-A-1-131214, JP-A-1-131215 and the like are preferably used.
Among these, polymers having the following heterocyclic structures are typical. However, the contents of the present invention are not limited to these.

However, in the general formulas (i) and (ii), Rf ₁ , Rf ₂ , and Rf ₃ each represent a fluorine-containing alkyl group.

Furthermore, in order to improve the adhesion with the substrate, control the glass transition temperature (Tg), and the solubility in a solvent, a structure represented by the following general formula (iii) is introduced into the main chain. Alternatively, these structures can be obtained by copolymerizing with a comonomer represented by the following structural formula (vii) to structural formula (ix).

However, in the general formula (iii), R ₄ , R ₅ , and R ₆ each represent a hydrogen atom, a fluorine atom, a chlorine atom, or Rf ₄ . However, Rf ₄ is a fluorine-containing alkyl group. X represents a hydrogen atom, a fluorine atom, a chlorine atom, Rf ₅ or Rf ₆ . However, Rf ₅ is a fluorine-containing organic substituent having a functional machine such as an acid, ester, alcohol, amine, or amide at the terminal, and Rf ₆ is a fluorine-containing alkyl group or a fluorine-containing ether group.

Suitable examples of the ink repellent treatment agent having the above-described specific chemical structure include, for example, trade name: CYTOP CTX-105 (manufactured by Asahi Glass Co., Ltd.), trade name: CYTOP CTX-805 ( Asahi Glass Co., Ltd.), trade name: Teflon (registered trademark) AF1600, trade name: AF2400 (manufactured by DuPont), and the like.

Examples of the method for forming an ink repellent film using a polymer having a fluorine-containing heterocyclic structure in the main chain include, for example, spin coating using a fluorine-based solvent, roll coating, coating such as dipping, printing, vacuum deposition, or the like. Is mentioned.
The fluorine-based solvent is not particularly limited as long as it can dissolve the polymer having a fluorine-containing heterocyclic structure in the main chain, and can be appropriately selected depending on the purpose. For example, perfluoro Benzene, "Product name: Aflude" (Product name: Asahi Glass Co., Ltd. fluorine-based solvent), "Fluorinert FC-75" (Product name: 3M liquid containing perfluoro(2-butyltetrahydrofuran)), etc. The fluorine-containing solvent of is preferable. These may be used alone or in combination of two or more. Among these, in the case of a mixed solvent, a hydrocarbon type, a chlorinated hydrocarbon, a fluorinated hydrocarbon, an alcohol, or another organic solvent can be used together.
The solution concentration is preferably 0.01% by mass or more and 50% by mass or less, and more preferably 0.01% by mass or more and 20% by mass or less.
If the average thickness of the ink repellent film is 0.01 μm or more, the above object can be sufficiently achieved, but 0.01 μm or more and 2 μm or less is preferable.

The heat treatment condition (temperature) of the polymer having a fluorine-containing heterocyclic structure in the main chain is determined by the boiling point of the solvent, the glass transition temperature of the polymer, and the heat resistant temperature of the base material. That is, a temperature higher than the boiling point of the solvent and the glass transition temperature of the polymer but lower than the heat resistant temperature of the base material may be selected.
The glass transition temperature of the polymer having a fluorine-containing heterocyclic structure in the main chain varies depending on its structure. For example, many of the structures of the structural formulas (iv) to (vi) are 50° C. or higher and 110° C. or lower; therefore, the heat treatment conditions are temperature 120° C. or higher and 170° C. or lower, and time is 30 minutes. ~2 hours are preferred.

Further, the copolymer having the structure of the general formula (ii) and the structure of the following structural formula (x) in the main chain is issued by DuPont under the trade name of "Teflon (registered trademark) AF".

The Teflon AF can have various glass transition temperatures by changing its copolymerization ratio. That is, the glass transition temperature increases as the ratio of the PDD [perfluoro(2,2-dimethyl-1,3-dioxole)] component increases. Depending on the component ratio, it exists up to about 80° C. to 330° C., and the commercially available ones are 160° C. (AF1600) and 240° C. (AF2400). For example, the heat treatment temperature of 160° C. is preferably 165° C. or higher and 180° C. or lower in consideration of the heat resistant temperature of the substrate.

-Other components-
The other members are appropriately selected depending on the intended purpose without any limitation, and examples thereof include a pressurizing chamber and a stimulus generating unit.

−−Pressure chamber−−
The pressurizing chamber is a plurality of individual channels that are arranged corresponding to the plurality of nozzle holes provided in the nozzle plate, and communicate with the nozzle holes, and are an ink channel, a pressurized liquid chamber, It may also be called a pressure chamber, a discharge chamber, a liquid chamber, or the like.

--- Means for ejecting ink ---
The ink ejection head has means for generating a stimulus applied to the ink.
The stimulus in the stimulus generating means is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include heat (temperature), pressure, vibration, and light. These may be used alone or in combination of two or more. Among these, heat and pressure are preferable.
Examples of the stimulus generating means include a heating device, a pressurizing device, a piezoelectric element, a vibration generating device, an ultrasonic oscillator, and a light. As the stimulus generation means, specifically, a piezoelectric actuator such as a piezoelectric element, a thermal actuator that uses a phase change due to film boiling of ink using an electrothermal conversion element such as a heating resistor, and a metal phase change due to a temperature change Shape memory alloy actuators using, and electrostatic actuators using electrostatic force can be cited.

When the stimulus is "heat", thermal energy corresponding to the recording signal is applied to the ink in the ink ejection head by using, for example, a thermal head or the like. There is a method of generating bubbles in the ink by the thermal energy and ejecting the ink as droplets from the nozzle holes of the nozzle plate by the pressure of the bubbles.
When the stimulus is “pressure”, for example, the piezoelectric element is bent by applying a voltage to the piezoelectric element bonded to a position called the pressure chamber in the ink flow path in the ink ejection head. .. As a result, the volume of the pressure chamber is contracted, and the ink is ejected as droplets from the nozzle holes of the ink ejection head.
Among these, the piezo system in which a voltage is applied to the piezo element to eject the ink is preferable.

Here, an example of the ink ejection head used in the present invention will be described with reference to FIGS. 4 to 6. 4 is an exploded perspective view of the same head, FIG. 5 is a cross-sectional explanatory view along a direction (longitudinal direction of the liquid chamber) orthogonal to the nozzle arrangement direction of the same head, and FIG. 6 is a nozzle arrangement direction of the same head (liquid chamber). It is a cross-sectional explanatory view along the lateral direction).

The ink discharge head includes a flow path plate (liquid chamber substrate, flow path member) 1, a vibration plate member 2 bonded to the lower surface of the flow path plate 1, and a nozzle forming member bonded to the upper surface of the flow path plate 1. A nozzle plate 3 and a plurality of nozzle holes 4 for ejecting droplets (ink droplets) by these nozzle plates 3 communicate with each other via nozzle communication passages 5 as a plurality of liquid chambers (pressurized liquids). (Also referred to as a chamber, a pressure chamber, a pressurizing chamber, a flow path, etc.) 6, a fluid resistance portion 7 also serving as a supply path for supplying ink to the liquid chamber 6, and a fluid chamber 6 via the fluid resistance portion 7. Ink is supplied from the common liquid chamber 10 formed in the frame member 17 through the supply port 19 formed in the diaphragm member 2 to the communicating portion 8 which is in communication with the communicating portion 8.

The flow path plate 1 is formed by etching a silicone substrate to form openings such as the communication passage 5, the liquid chamber 6, and the fluid resistance portion 7. The flow channel plate 1 can also be formed, for example, by etching a SUS substrate using an acidic etching solution or by mechanical processing such as punching (pressing).

The vibrating plate member 2 has respective vibrating regions (diaphragm parts) 2a that form the wall surfaces corresponding to the respective liquid chambers 6, and island-shaped convex portions are formed on the outside of the vibrating region 2a (on the side opposite to the liquid chambers 6). 2b is provided, and each of the laminated piezoelectric elements 12 and 12 as a driving element (actuator means, pressure generating means) that deforms the vibration region 2a in the island-shaped convex portion 2b and generates energy for ejecting liquid droplets. The upper end surfaces (bonding surfaces) of the piezoelectric element columns 12A and 12B are bonded. The lower end surface of the laminated piezoelectric element 12 is joined to the base member 13.

Here, the piezoelectric element 12 is formed by alternately laminating the piezoelectric material layer 21 such as PZT and the internal electrodes 22a and 22b, and the internal electrodes 22a and 22b are respectively formed on the end faces, that is, the diaphragm member 2 of the piezoelectric element 12. By pulling it out to a substantially vertical side surface, connecting it to the end surface electrodes (external electrodes) 23a and 23b formed on this side surface, and applying a voltage to the end surface electrodes (external electrodes) 23a and 23b, displacement in the stacking direction occurs. The piezoelectric element 12 is formed by performing groove processing by half-cut dicing and forming a required number of piezoelectric element columns 12A and 12B on one piezoelectric element member.

The piezoelectric element columns 12A and 12B of the piezoelectric element 12 are the same, but the piezoelectric element columns that are driven by applying a drive waveform are used as the piezoelectric element column 12A and a simple column without applying a drive waveform. Are distinguished as the piezoelectric element columns 12B. In this case, either the bi-pitch configuration in which the driving piezoelectric element columns 12A and the column piezoelectric element columns 12B are alternately used or the normal pitch configuration in which all the piezoelectric element columns are used as the driving piezoelectric element columns 12A is used. Can be adopted.

As a result, two drive element rows (rows of the drive piezoelectric element columns 12A) in which a plurality of drive piezoelectric element columns 12A as drive elements are arranged side by side are provided on the base member 13.

Further, the piezoelectric element 12 is configured to press the ink in the liquid chamber 6 by using displacement in the d33 direction (piezoelectric material layer laminating direction) as the piezoelectric direction. However, the piezoelectric direction of the laminated piezoelectric element 12 is the d31 direction. It is also possible to adopt a configuration in which the ink in the pressurized liquid chamber 6 is pressurized by using the displacement (the surface direction of the piezoelectric material layer: the direction orthogonal to the electric field).

In addition, the piezoelectric element material is not particularly limited, and an electromechanical conversion element such as a ferroelectric material such as BaTiO ₃ , PbTiO ₃ , (NaK)NbO ₃ or the like which is generally used as a piezoelectric element material can also be used. Furthermore, although a laminated type piezoelectric element is used, a single-plate piezoelectric element may be used. The single-plate piezoelectric element may be a machined one, a thick film screen-printed and sintered, or a thin film formed by sputtering, vapor deposition, or a sol-gel method. Further, the laminated piezoelectric element 12 provided on one base member 13 may be provided in one row or in a plurality of rows.

Then, an FPC 15 as a wiring means is directly connected to the external electrode 23a of each driving piezoelectric element column 12A of the piezoelectric element 12 by a solder member in order to give a driving signal, and each driving piezoelectric element of the piezoelectric element 12 is connected to this FPC 15. A drive circuit (driver IC) 16 for selectively applying a drive waveform to the element column 12A is mounted. The external electrodes 23b of all the piezoelectric element columns 12A are electrically connected in common and are also connected to the common wiring of the FPC 15 by the solder member. Further, here, the output terminal portion of the FPC 15 that is joined to the piezoelectric element 12 is plated with solder to enable solder joining. However, if the piezoelectric element 12 side, not the FPC 15, is plated with solder. Good. Further, as a joining method, joining by an anisotropic conductive film or wire bonding may be used in addition to solder joining.

The nozzle plate 3 has a droplet ejection side surface (a surface in the ejection direction: an ejection surface, or a ejection surface, or the ejection surface of the nozzle base material 31 in which a hole portion forming a nozzle hole 4 having a diameter of 10 μm or more and 35 μm or less is formed corresponding to each liquid chamber 6. An ink repellent film 32 is formed on the surface opposite to the liquid chamber 6 side, that is, the nozzle forming surface).

A frame member 17 formed by injection molding with an epoxy resin or polyphenylene sulphite is provided on the outer peripheral side of the piezoelectric actuator unit 100 including the piezoelectric element 12 on which the FPC 15 is mounted (connected) and the base member 13. It is joined. Further, the common liquid chamber 10 described above is formed in the frame member 17, and a supply port 19 for supplying ink to the common liquid chamber 10 from the outside is further formed. The supply port 19 is further provided in a sub tank or an ink not shown. It is connected to an ink supply source such as a storage container.

In the ink discharge head configured as described above, for example, by lowering the voltage applied to the driving piezoelectric element column 12A from the reference potential, the piezoelectric element column 12A contracts, and the vibration region 2a of the diaphragm member 2 descends. As the volume of the liquid chamber 6 expands, ink flows into the liquid chamber 6, and then the voltage applied to the piezoelectric element column 12A is increased to extend the piezoelectric element column 12A in the stacking direction, and the vibrating plate member 2 is attached to the nozzle. By deforming the liquid chamber 6 in the direction of the holes 4 and contracting the volume/volume of the liquid chamber 6, the ink in the liquid chamber 6 is pressurized and droplets of the ink are ejected (jetted) from the nozzle holes 4.

Then, by returning the voltage applied to the piezoelectric element column 12A to the reference potential, the diaphragm member 2 is restored to the initial position, the liquid chamber 6 expands and negative pressure is generated, and at this time, from the common liquid chamber 10 Ink is filled in the liquid chamber 6. Therefore, after the vibration of the meniscus surface of the nozzle hole 4 is damped and stabilized, the operation moves to the next droplet ejection.

The method of driving the ink ejection head is not limited to the above example (pull-push ejection), and pull ejection or push ejection may be performed depending on the method of giving the drive waveform.

Next, details of the nozzle plate 3 according to the present invention will be described with reference to FIGS. 7 to 9. 7 is a plan explanatory view of the nozzle plate 3, FIG. 8 is a sectional explanatory view of the same, and FIG. 9 is an enlarged sectional explanatory diagram of one nozzle portion.
The nozzle plate 3 includes a Ti layer 33 as a base layer, a SiO ₂ film 34, and a perfluoropolyether film having an alkoxysilane in the molecule (this film is “Water repellent film”) 32 in this order from the surface of the nozzle base material 31. Then, in the vicinity of the outlet of the inner wall surface 4 a of the nozzle hole 4, a base layer (Ti layer) 33 is continuously formed on the SiO 2 film 35 formed on the liquid chamber surface 31 b of the nozzle base material 31 from the ejection surface. And the underlying layer (Ti layer) 33 is exposed on the outermost surface.

A Ni metal plate or the like can be used as the nozzle base material 31, but the nozzle base material 31 is not limited to this.

Here, the water-repellent layer 32 of the nozzle plate 3 is formed by vapor deposition, and the vapor-deposited film for forming the water-repellent layer 32 is not formed near the outlet of the inner wall surface of the nozzle hole 4. As a result, it is possible to perform stable droplet ejection without causing ejection failure or impairing the liquid filling property.

<Printing method and printing device>
The printing method of the present invention is a printing method of ejecting and printing the ink of the present invention, and includes at least an ink ejection step, and other steps appropriately selected as necessary, for example, a stimulus generation step, a control step, etc. including.
The printing apparatus of the present invention has at least an ink cartridge that contains the ink of the present invention, and an ink ejection unit that ejects ink, and other units that are appropriately selected as necessary, for example, a stimulus generation unit and a control unit. And so on.
The printing method of the present invention can be preferably carried out by the printing apparatus of the present invention, and the ink discharging step can be preferably carried out by the ink discharging means. Further, the other steps can be suitably performed by the other means.

-Ink ejection process (an example of printing process)-
The ink ejection step is a step of applying a stimulus (energy) to the ink and ejecting the ink onto a recording medium to print. In this step, a known inkjet recording method can be applied as a method of ejecting ink to print on a recording medium. Examples thereof include an inkjet recording method of scanning a head, and an inkjet recording method of recording an image on a recording medium of a sheet by using a lined head.
There is no particular limitation on the driving method of the recording head, which is an ink ejecting means, and a piezoelectric element actuator using PZT, a method of applying thermal energy, or an on-demand type head using an actuator using electrostatic force is used. Recording can also be performed with a continuous ejection type charge control type head.

In the printing method of the present invention, if necessary, a heating/drying step can be provided after the ink discharging step. For example, the recording medium is heated by an infrared drying device, a microwave drying device, a roll heater, a drum heater, or warm air. Can be dried.

An example of the printing device is shown in FIG.
This figure shows a case where an image forming step and a drying step are included. 1 is a recording medium, 2 is an ink ejecting section, 3 is a conveyor belt, 4 is a warm air drying device, 5 is an image forming section, and 6 is a drying process. Reference numeral 7 is a transfer roll.

<Recording device, recording method>
The ink of the present invention can be suitably used for various recording apparatuses using an inkjet recording system, such as printers, facsimile machines, copying machines, printer/fax/copier composite machines, and three-dimensional modeling apparatuses.
In the present invention, the recording device and the recording method are a device capable of ejecting ink, various treatment liquids, and the like onto a recording medium, and a method of recording using the device. The recording medium means a medium to which ink or various treatment liquids can be attached even temporarily.
This recording apparatus can include not only a head portion for ejecting ink, but also means for feeding, conveying, and discharging a recording medium, and other devices such as a pre-processing device and a post-processing device. ..
The recording device and the recording method may have a heating means used in the heating step and a drying means used in the drying step. The heating means and the drying means include, for example, means for heating and drying the printing surface or the back surface of the recording medium. The heating means and the drying means are not particularly limited, but, for example, a warm air heater or an infrared heater can be used. Heating and drying can be performed before printing, during printing, after printing, and the like.
Further, the recording device and the recording method are not limited to those in which a significant image such as a character or a figure is visualized by ink. For example, it also includes one that forms a pattern such as a geometric pattern and one that models a three-dimensional image.
Further, the recording apparatus includes both a serial type apparatus that moves the ejection head and a line type apparatus that does not move the ejection head unless otherwise limited.
Further, this recording device is not limited to a desktop type, but can be used as a wide recording device capable of printing on an A0 size recording medium, or a continuous paper wound in a roll, for example. It also includes a continuous form printer.
An example of the recording device will be described with reference to FIGS. FIG. 2 is a perspective explanatory view of the device. FIG. 3 is a perspective view of the main tank. The image forming apparatus 400 as an example of the recording apparatus is a serial type image forming apparatus. A mechanical section 420 is provided in the exterior 401 of the image forming apparatus 400. Each ink storage portion 411 of the main tank 410 (410k, 410c, 410m, 410y) for each color of black (K), cyan (C), magenta (M), and yellow (Y) is packed with, for example, an aluminum laminate film. It is formed of a member. The ink container 411 is housed in a container case 414 made of plastics, for example. As a result, the main tank 410 is used as an ink cartridge for each color.
On the other hand, a cartridge holder 404 is provided on the inner side of the opening when the cover 401c of the apparatus main body is opened. The main tank 410 is detachably attached to the cartridge holder 404. As a result, the ink discharge ports 413 of the main tank 410 communicate with the ejection heads 434 for the respective colors via the supply tubes 436 for the respective colors, and ink can be ejected from the ejection heads 434 to the recording medium.

It is preferable to have a filter between the ink flow path from the ink containing section (ink cartridge) 411 to the ejection head (ejection means for ejecting ink) 434 in FIG. Further, a filter may be provided at the ink discharge port 413. The filter is preferably a filter capable of holding particles of 10 μm or more, and by providing the filter, particles of 10 μm or more can be removed, and a printing apparatus having excellent ejection stability can be provided.
Since the filter is always in contact with the ink, it is preferably made of stainless steel from the viewpoint of corrosion resistance. Among them, austenitic stainless steel is more preferable because of its excellent corrosion resistance, and more particularly SUS304, SUS316 or SUS316L. Is desirable. The filter preferably contains any one selected from SUS304, SUS316 and SUS316L, more preferably any one of them.

Further, as the filter, filters having different filtration accuracy are commercially available, and for example, Acro Last Chance Filter manufactured by Nippon Pole Co., Ltd. can be used. It is preferable to use a filter having a filtration accuracy of 10 μm or less, because the solid content present in the ink can be removed and the ejection stability can be improved. It is preferable to use a filter having a filtration accuracy of 6 μm or more and 10 μm or less because ink can be appropriately supplied to the ejection unit.
Specific products include, for example, 10 μm disposable filter, PALL ACRO25 LCF-12100, filtration accuracy: 10 μm, and material: polypropylene.

An ink containing water, an organic solvent, polyurethane resin particles, and a cyclic ester having a structure represented by the general formula (I), which is stored for one month in a room temperature environment (25±5° C.) and then stored in the general formula ( By using an ink in which the content of crystals having a particle size of 1 μm or more of the cyclic ester having the structure shown in I) is less than 4 ppm of the total ink, fixing to non-penetrating media for signage and commercial printing paper It is possible to provide an ink, a printing method, and a printing apparatus that are excellent in storage stability, drying property, high image density, liquid permeability and ejection stability, and excellent storage stability.

By using a printing device provided with a filter between the ink flow path from the ink cartridge to the ejecting means for ejecting ink, it is possible to remove crystals existing in the ink, for example, particles having a particle size of more than 10 μm, which is preferable. Ejection stability can be obtained.

In a process for producing an ink containing at least water, an organic solvent and polyurethane resin particles, after the step of mixing water, an organic solvent and polyurethane resin particles, the resulting mixture is heated at 40° C. or higher and lower than 70° C. for 6 hours or longer. By providing the step, the content of crystals having a particle size of 1 μm or more of the cyclic ester having the structure represented by the general formula (I) in the ink can be less than 4 ppm in the entire ink. By lowering the content of the cyclic ester having the structure represented by the general formula (I) in the ink, the fixing property and the drying property are high, the image density is high, the liquid permeability and the ejection stability are good, and the storage stability is high. The ink can have excellent properties. Regarding crystals, even when large crystals having a particle size of more than 10 μm remain, it is considered that more suitable ejection stability can be obtained by removing the large crystals with a filter.

The shape of the filter used in the present invention is not particularly limited, and any known filter can be used. Among them, if a sintered filter formed by stacking stainless fibers in a felt shape and sintered or a twill weave filter formed by twill weaving stainless fibers is used, inkjet recording with longer-term ejection reliability can be achieved. It is desirable because a device (ink supply unit) can be obtained.

Further, in the terms of the present invention, image formation, recording, printing, printing and the like are synonymous.

A recording medium, a medium, and a material to be printed are synonymous with each other.

Hereinafter, the present invention will be described in more detail with reference to Preparation Examples, Production Examples, Examples and Comparative Examples, but the present invention is not limited to these Examples. In addition, "part" and "%" in an example are a "mass part" and "mass %" unless there is particular notice.
In addition, unless otherwise specified, the ink was prepared and evaluated under the conditions of room temperature of 25° C. and humidity of 60%.

<Preparation of pigment dispersion>
(Preparation example 1)
-Preparation of surface modified black pigment dispersion-
Black Pearls (registered trademark) 1000 (carbon black of BET specific surface area 343 m2/g, dibutyl phthalate absorption amount (DBPA) 105 mL/100 g) manufactured by Cabot Corporation, 100 g, 100 mmol of sulfanilic acid and 1 L of ion-exchanged pure water were used at room temperature in a Silverson mixer. (6000 rpm). Next, 100 mmol of nitric acid was added to the obtained slurry, and after 30 minutes, sodium nitrite (100 mmol) dissolved in 10 mL of ion-exchanged pure water was slowly added. The mixture was further heated to 60° C. with stirring and reacted for 1 hour to obtain a modified pigment in which sulfanilic acid was added to carbon black. Next, the pH was adjusted to 9 with a 10% tetrabutylammonium hydroxide solution (methanol solution), and after 30 minutes, a modified pigment dispersion was obtained. Next, ultrafiltration with a dialysis membrane was performed using this dispersion and ion-exchanged high-purity water, and then ultrasonic dispersion was performed to obtain a modified pigment dispersion containing 20% of pigment solids. The surface treatment level of the pigment was 0.75 mmol/g, and the median diameter (D50) measured with a particle size distribution analyzer (Nanotrack UPA-EX150 manufactured by Nikkiso Co., Ltd.) was 120 nm.

(Preparation example 2)
-Preparation of surface-modified magenta pigment dispersion-
1 kg of pigment dispersion SMART Magenta 3122BA (Pigment Red 122 surface-treated dispersion, pigment solid content 14.5%) manufactured by SENSIENT was acid-deposited with a 0.1 N HCl aqueous solution. Next, the pH was adjusted to 9 with a 10% tetraethylammonium hydroxide aqueous solution, and after 30 minutes, a modified pigment dispersion was obtained. The modified pigment dispersion containing a pigment bonded to at least one aminobenzoic acid group or tetraethylammonium aminobenzoate salt is subjected to ultrafiltration with a dialysis membrane using ion-exchanged high-purity water, and ultrasonically dispersed to further disperse the pigment. A modified pigment dispersion containing 20% solids was obtained. The median diameter (D50) measured with a particle size distribution measuring device (Nanotrack UPA-EX150 manufactured by Nikkiso Co., Ltd.) was 104 nm.

(Preparation example 3)
-Preparation of surface modified cyan pigment dispersion-
1 kg of a pigment dispersion SMART Cyan 3154BA (Pigment Blue 15:4 surface-treated dispersion, pigment solid content 14.5%) manufactured by SENSIENT was acid-deposited with a 0.1 N HCl aqueous solution. Next, the pH was adjusted to 9 with a 40% benzyltrimethylammonium hydroxide solution (methanol solution), and after 30 minutes, a modified pigment dispersion was obtained. The modified pigment dispersion containing a pigment bound to at least one aminobenzoic acid group or benzyltrimethylammonium aminobenzoate and ion-exchanged pure water are used for ultrafiltration through a dialysis membrane, and then ultrasonic dispersion is performed. A modified pigment dispersion containing 20% pigment solids was obtained. The median diameter (D50) measured with a particle size distribution analyzer (Nanotrack UPA-EX150 manufactured by Nikkiso Co., Ltd.) was 116 nm.

(Preparation example 4)
-Preparation of surface modified yellow pigment dispersion-
SENSIENT pigment dispersion SMART Yellow 3074BA (Pigment Yellow 74 surface-treated dispersion, pigment solid content 14.5%) 1 kg was adjusted to pH 9 with 10% tetrabutylammonium hydroxide solution (methanol solution), and after 30 minutes. A modified pigment dispersion was obtained. Ultrafiltration is performed through a dialysis membrane using the modified pigment dispersion containing a pigment bonded to at least one aminobenzoic acid group or tetrabutylammonium aminobenzoate salt and ultrapure water, and ultrasonic dispersion is further performed. A modified pigment dispersion containing 20% of pigment solids was obtained. The median diameter (D50) measured with a particle size distribution measuring device (Nanotrack UPA-EX150 manufactured by Nikkiso Co., Ltd.) was 145 nm.

(Preparation example 5)
-Preparation of magenta pigment-containing polymer particle dispersion-
<Preparation of polymer solution A>
After thoroughly replacing the inside of a 1 L flask equipped with a mechanical stirrer, a thermometer, a nitrogen gas introduction tube, a reflux tube, and a dropping funnel with nitrogen gas, 11.2 g of styrene, 2.8 g of acrylic acid, and 12.0 g of lauryl methacrylate. , Polyethylene glycol methacrylate 4.0 g, styrene macromer 4.0 g, and mercaptoethanol 0.4 g were mixed, and the temperature was raised 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 dropped 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 further aging was performed for 1 hour. After completion of the reaction, 364 g of methyl ethyl ketone was added into the flask to obtain 800 g of a polymer solution A having a concentration of 50% by mass.

<Preparation of pigment-containing polymer particle dispersion>
After sufficiently stirring 28 g of the polymer solution A, 42 g of CI Pigment Red 122, 13.6 g of a 1 mol/L potassium hydroxide aqueous solution, 20 g of methyl ethyl ketone, and 13.6 g of ion-exchanged water, a roll mill was used. Kneaded 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. Further, in order to remove coarse particles, this dispersion was mixed with polyvinylidene fluoride having an average pore size of 5.0 μm. The mixture was filtered under pressure with a membrane filter to obtain a magenta pigment-containing polymer fine particle dispersion liquid containing 15% by mass of pigment and 20% by mass of solid content. When the median diameter (D50) of the polymer particles in the obtained magenta pigment-containing polymer particle dispersion was measured, it was 127 nm. The median diameter (D50) was measured using a particle size distribution measuring device (Nanotrack UPA-EX150, manufactured by Nikkiso Co., Ltd.).

(Preparation example 6)
-Preparation of Cyan Pigment-Containing Polymer Fine Particle Dispersion-
Cyan pigment-containing polymer fine particle dispersion liquid in the same manner as in Preparation Example 5 except that CI Pigment Red 122 as a pigment was changed to a phthalocyanine pigment (CI Pigment Blue 15:3) in Preparation Example 5. Was prepared.
The polymer fine particles in the obtained cyan pigment-containing polymer fine particle dispersion had a median diameter (D50) of 93 nm measured by a particle size distribution measuring device (Nanotrack UPA-EX150, manufactured by Nikkiso Co., Ltd.).

(Preparation example 7)
-Preparation of yellow pigment-containing polymer particle dispersion-
A yellow pigment-containing polymer fine particle dispersion liquid was prepared in the same manner as in Preparation Example 5 except that CI Pigment Red 122 as a pigment was changed to a bisazo yellow pigment (CI Pigment Yellow 155) in Preparation Example 5. Was prepared.
The polymer fine particles in the obtained yellow pigment-containing polymer fine particle dispersion had a median diameter (D50) of 76 nm as measured by a particle size distribution measuring device (Nanotrack UPA-EX150, manufactured by Nikkiso Co., Ltd.).

(Preparation Example 8)
-Preparation of polymer fine particle dispersion containing carbon black pigment-
A carbon black pigment-containing polymer fine particle dispersion liquid was prepared in the same manner as in Preparation Example 5, except that the CI pigment red 122 as a pigment was changed to carbon black (FW100, manufactured by Degussa). ..
The median diameter (D50) of the polymer fine particles in the obtained carbon black pigment-containing polymer fine particle dispersion liquid measured by a particle size distribution measuring device (Nanotrack UPA-EX150, manufactured by Nikkiso Co., Ltd.) was 104 nm.

<Preparation example of resin particles>
<Preparation of water-dispersible polyurethane resin (A)>
(Preparation of polyester polyol P-1)
While introducing nitrogen gas into a reaction vessel equipped with a thermometer, a nitrogen gas introducing tube, and a stirrer, 830 parts of terephthalic acid, 830 parts of isophthalic acid, 374 parts of ethylene glycol, 598 parts of neopentyl glycol and 0.5 parts of dibutyltin oxide. And a polycondensation reaction was performed at 180 to 230° C. for 15 hours at 230° C. until the acid value became 1 or less to obtain a polyester polyol P-1 having a hydroxyl value of 74.5, an acid value of 0.2 and an average molecular weight of 1500. It was

(Preparation of Hydrophobic Polyester Polyol Q-1)
While introducing nitrogen gas into a reaction vessel equipped with a thermometer, a nitrogen gas introduction tube, and a stirrer, 1660 parts of orthophthalic acid, 1637 parts of diethylene glycol and 0.5 part of dibutyltin oxide were charged, and an acid value of 180 to 230° C. was 1 Polycondensation reaction was carried out at 230° C. for 15 hours until the temperature became below, to obtain a polyester polyol Q-1 having an aromatic cyclic structure having a hydroxyl value of 190 and an acid value of 0.3.

(Preparation of water-dispersible polyurethane resin (A))
1000 parts of polyester polyol P-1 was dehydrated at 100° C. under reduced pressure, then cooled to 80° C., 907 parts of methyl ethyl ketone was added and sufficiently dissolved to dissolve, and 80 parts of 2,2′-dimethylolpropionic acid was added, Then, 281 parts of isophorone diisocyanate was added and reacted at 75° C. for 8 hours to carry out the urethanization step.
After confirming that the isocyanate value became 0.1% or less, the mixture was cooled to 50° C., 340 parts of the polyester polyol Q-1 was added to form a uniform solution, and then 60 parts of triethylamine was added to neutralize the mixture. Water (7,000 parts) was added to solubilize it.
After removing methyl ethyl ketone from the obtained transparent reaction product under reduced pressure at 40 to 60° C., water was added to adjust the concentration to obtain a stable semi-transparent colloidal aqueous dispersion having a nonvolatile content of 25%. ..

<Preparation of water-dispersible polyurethane resin (B)>
After dehydrating 1000 parts of the above-mentioned polyester polyol P-1 at 100° C. under reduced pressure, and then cooling to 80° C., 907 parts of methyl ethyl ketone was added and sufficiently stirred to dissolve, 80 parts of 2,2′-dimethylolpropionic acid. Was added, and then 281 parts of isophorone diisocyanate was added and reacted at 75° C. for 8 hours to carry out the urethanization step.
After confirming that the isocyanate value became 0.1% or less, the mixture was cooled to 50° C., neutralized by adding 60 parts of triethylamine, and then water-solubilized by adding 7,000 parts of water.
After removing methyl ethyl ketone from the obtained transparent reaction product under reduced pressure at 40 to 60° C., water was added to adjust the concentration to obtain a stable semi-transparent colloidal aqueous dispersion having a nonvolatile content of 25%. ..

<Preparation of water-dispersible polyurethane resin (C)>
(Preparation of polyester polyol P-2)
While introducing nitrogen gas into a reaction vessel equipped with a thermometer, a nitrogen gas introduction tube, and a stirrer, 664 parts of terephthalic acid, 631 parts of isophthalic acid, 472 parts of 1,4-butanediol, 447 parts of neopentyl glycol and dibutyltin. After 0.5 part of oxide was charged and esterification was carried out at 180 to 230° C. for 5 hours, a polycondensation reaction was carried out at 230° C. for 6 hours until the acid value became 1 or less. Then, the mixture was cooled to 120° C., 321 parts of adipic acid and 268 parts of 2,2′-dimethylolpropionic acid were added, the temperature was again raised to 170° C., and the reaction was carried out at this temperature for 20 hours to give an acid value of 46.5 and a hydroxyl value of 59. A polyester polyol P-2 having a carboxyl group of 0.8 was obtained.

(Preparation of water-dispersible polyurethane resin (C))
1000 parts of polyester polyol P-2 was dehydrated at 100° C. under reduced pressure, then cooled to 80° C., 812 parts of methyl ethyl ketone was added and dissolved sufficiently with stirring, 20 parts of 1,4-butanediol was added, and then dicyclohexylmethane-4. , 4′-diisocyanate (hydrogenated MDI) (198 parts) was added, and the mixture was reacted at 75° C. for 8 hours.
After confirming that the isocyanate value became 0.1% or less, the mixture was cooled to 50° C., neutralized by adding 84 parts of triethylamine, and then water-solubilized by adding 7,000 parts of water.
After removing methyl ethyl ketone from the obtained transparent reaction product under reduced pressure at 40 to 60° C., water was added to adjust the concentration to obtain a stable semi-transparent colloidal aqueous dispersion having a nonvolatile content of 25%. ..

<Preparation of water-dispersible polyurethane resin (D)>
1000 parts of polyester polyol P-1 was dehydrated at 100° C. under reduced pressure, then cooled to 80° C., 907 parts of methyl ethyl ketone was added and sufficiently dissolved to dissolve, and 80 parts of 2,2′-dimethylolpropionic acid was added, Then, 281 parts of isophorone diisocyanate was added and reacted at 75° C. for 8 hours to carry out the urethanization step.
After confirming that the isocyanate value became 0.1% or less, the mixture was cooled to 50° C., neutralized by adding 60 parts of triethylamine, and then water-solubilized by adding 7,000 parts of water.
After removing methyl ethyl ketone from the obtained transparent reaction product under reduced pressure at 40 to 60° C., water was added to adjust the concentration to obtain a stable semi-transparent colloidal aqueous dispersion having a nonvolatile content of 25%. ..

<Preparation of acrylic-silicone polymer particles A>
After thoroughly replacing the inside of a 1 L flask equipped with a mechanical stirrer, a thermometer, a nitrogen gas introduction tube, a reflux tube, and a dropping funnel with nitrogen gas, to 350 g of ion-exchanged water, 8.0 g of Latemur S-180 (Kao) (Manufactured by Reactive Anionic Surfactant) was added and mixed, and the temperature was raised to 65°C. Then, 3.0 g of t-butyl peroxobenzoate as a reaction initiator and 1.0 g of sodium isoascorbate were added, and after 5 minutes, 45 g of methyl methacrylate, 160 g of 2-ethylhexyl methacrylate, 5 g of acrylic acid, 45 g of butyl methacrylate. A mixture of 30 g of cyclohexyl methacrylate, 15 g of vinyltriethoxysilane, 8.0 g of Latemur S-180, and 340 g of deionized water was added dropwise over 3 hours. Next, the mixture was heat-aged at 80° C. for 2 hours, cooled to room temperature, and adjusted to pH 7-8 with sodium hydroxide. Next, ethanol was distilled off by an evaporator and the water content was adjusted to obtain 730 g of acrylic-silicone polymer fine particles having a solid content of 40%. The median diameter (D50) of the polymer particles in the dispersion was 125 nm when measured with a particle size distribution analyzer (Nanotrack UPA-EX150, manufactured by Nikkiso Co., Ltd.).

(Examples 1-26 and Comparative Examples 1-21)
<Production example of pre-ink>
(Pre-ink production example 1)
In a container equipped with a stirrer, 7.50 parts of 3-methoxy-N,N-dimethylpropanamide represented by the above formula (1), 5.00 parts of propylene glycol monopropyl ether, 18.00 parts of propylene glycol, 2,2,4-trimethyl-1,3-pentanediol (2.00 parts) and 2,4,7,9-tetramethyldecane-4,7-diol (0.50 parts) represented by the above formula (8). 1.00 parts of a polyether-modified siloxane compound was added and mixed and stirred for 30 minutes. Next, the antiseptic/antifungal agent (Proxel GXL manufactured by Avicia Co., Ltd.) 0.05 part, 2-amino-2-ethyl-1,3-propanediol 0.30 part, and the prepared water-dispersible polyurethane resin (A) 56 1.00 parts, 1.62 parts of polyurethane dispersion "Takelac W-6110" manufactured by Mitsui Chemicals, Inc., and high-purity water in an amount of 100 parts as a whole were added and mixed and stirred for 60 minutes. Then, the obtained mixture was pressure-filtered with a polyvinylidene fluoride membrane filter having an average pore size of 1.2 μm to remove coarse particles and dust to obtain Pre-ink 1.

(Pre-ink production example 2)
In a container equipped with a stirrer, 7.50 parts of 3-methoxy-N,N-dimethylpropanamide represented by the above formula (1), 5.00 parts of propylene glycol monopropyl ether, 22.00 parts of propylene glycol, 2.00 parts of 2-ethyl-1,3-hexanediol, 0.50 parts of 2,4,7,9-tetramethyldecane-4,7-diol, and polyether modification represented by the above formula (8) 1.50 parts of a siloxane compound was added and mixed and stirred for 30 minutes. Next, 0.05 parts of antiseptic/antifungal agent (Proxel GXL manufactured by Avicia), 0.30 part of 2-amino-2-ethyl-1,3-propanediol, and 24 parts of the prepared water-dispersible polyurethane resin (A) 2.00 parts, 1.62 parts of polyurethane dispersion "Takelac W-6110 manufactured by Mitsui Chemicals, Inc.", 15.00 parts of the surface-modified black pigment dispersion of Preparation Example 1, and 100 parts of high pure water as a whole. The mixture was added and stirred for 60 minutes. Then, the obtained mixture was subjected to pressure filtration with a polyvinylidene fluoride membrane filter having an average pore size of 1.2 μm to remove coarse particles and dust to obtain Pre-ink 2.

(Pre-ink production examples 3 to 24)
In the same manner as in Preink Production Examples 1 and 2, the organic solvent, the surfactant and the defoaming agent shown in each column of Preink Production Examples 3 to 24 in Tables 1 to 3 below are mixed and stirred, and then the antiseptic and fungicide is added. The pH adjusting agent and the colorant (pigment dispersion) were mixed and stirred, and the water-dispersible polyurethane resin and the resin particles were further mixed and stirred. The obtained mixture was pressure-filtered with a polyvinylidene fluoride membrane filter having an average pore size of 1.2 μm to remove coarse particles and dust, thereby obtaining pre-inks 3 to 24.

Details such as abbreviations in Tables 1 to 3 are as follows.
-Direct Blue 199 (water-soluble cyan dye): manufactured by EKTA INTERNATIONAL-Superflex 300: polyurethane dispersion, solid content 30.0%,
Tg=-42°C, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.-Takelac W-6110: polyurethane dispersion, solid content 30.9%,
Tg=-20°C, manufactured by Mitsui Chemicals, Inc.-Compound of formula (1): 3-methoxy-N,N-dimethylpropanamide-Compound of formula (2): 3-n-butoxy-N,N-dimethylpropanamide -Compound of formula (5): 3-ethyl-3-hydroxymethyloxetane-Compound of formula (6): 3-methyl-3-hydroxymethyloxetane-TEGO Wet270: polyether-modified siloxane compound
(Evonik, 100% active ingredient)
・Silface SAG503A: Polyether-modified siloxane compound
(Nissin Chemical Industry Co., Ltd., 100% active ingredient)
・Unidyne DSN403N: Polyoxyethylene perfluoroalkyl ether
(Daikin Industries, Ltd., 100% active ingredient)
-Proxel GXL: 1,2-benzisothiazolin-3-one
Antiseptic and fungicide containing the main component
(Avicia product, 20% component, dipropylene glycol included)

The physical properties of each ink of Pre-ink Production Examples 1 to 24 were measured as follows. The results are shown in Table 4.
<Viscosity>
It measured at 25 degreeC using the viscometer (RE-85L, Toki Sangyo Co., Ltd.).
<pH>
It measured at 25 degreeC using the pH meter meter (HM-30R type, TOA-DKK make).
<Static surface tension>
It measured at 25 degreeC using the automatic surface tension meter (DY-300, Kyowa Interface Science Co., Ltd.).
<Dynamic surface tension>
The dynamic surface tension of the ink of the present invention was measured at 25° C. using a SITA_DynoTester (manufactured by SITA) at a surface life of 15 msec according to the maximum bubble pressure method.

<Ink production example>
Inks 1 to 27 were obtained by heating the pre-inks 1 to 24 under the conditions shown in Table 5. For each ink, the physical properties were measured in the same manner as for the pre-ink.
The results are shown in Table 5.

The pre-ink and the ink heated under each condition were filled in an ink pack, and the ink stored at room temperature (25±5° C.) for 1 month was used to evaluate and form an image as follows, The characteristics were evaluated. The results are shown in Table 6.

-Qualitative and quantification of crystals of cyclic ester having a structure represented by the general formula (I) contained in the ink-
<Qualitative method, quantification method>
To quantify the crystals of the cyclic ester having the structure represented by the general formula (I) contained in the ink, each ink of the production example is simply put in a Kiriyama funnel of Φ60 mm and filter paper Φ60 mm No. for Kiriyama funnel. Filtration is performed with a filtration jig in which 5 C (particle retention capacity 1 μm) is set, and after the filtration, the retained crystals and filter paper are thoroughly washed with high-purity water and dried to the water content of the filter paper before filtering. The weight of the filter paper before filtration and the weight of the crystals retained after filtration and the weight of the filter paper are weighed to obtain the difference, whereby the quantification of the cyclic ester crystal having the structure represented by the general formula (I) becomes possible.
The amount of ink to be filtered here was quantified by filtering 3000 g of ink in order to improve the quantification accuracy.
All the crystals on the filter paper were dissolved with tetrahydrofuran, and the remaining filter paper was dried and weighed. Further, the difference between the weight of the weighed filter paper and the weight of the weighed filter paper before filtration was confirmed, but there was no difference. In addition, the solution dissolved in tetrahydrofuran was subjected to LC-MS analysis to confirm that it did not contain other components. The structure of crystals precipitated in the ink and obtained by filtration is qualitatively determined by GC-MS analysis and LC-MS analysis+C ¹³ -NMR+H ¹ -NMR+FT-IR, and all are represented by the following structural formula (B). It was confirmed to be a cyclic ester having a structure.

-Ink ejection process (image forming process)-
Under environmental conditions adjusted to 23±0.5° C. and 50±5% RH, an inkjet recording device (IPSiO GXe-5500, manufactured by Ricoh Co., Ltd.) is used to drive the piezo element so that the ink ejection amount becomes uniform. The voltage was changed so that the same amount of ink was attached to the recording medium (manufactured by Oji Paper Co., Ltd.: OK top coat+_US basis weight 104.7 g/m ² ). Further, in Examples 18, 19 and Comparative Examples 18 and 19, a filter was installed between the ink storage section (ink cartridge) and the ink flow path up to the ejection head (ejection means for ejecting ink).
As the filter, the following Acro Last Chance Filter manufactured by Nippon Pole Co., Ltd. was used.
10 μm disposable filter: PALL ACRO25 LCF-12100, filtration accuracy: 10 μm,
Material: polypropylene

Next, the production of the nozzle plate mounted on the inkjet head will be described.
(Production Example 101)
<Production of nozzle plate A>
<<Synthesis of Fluorine-Containing Acrylate Ester Polymer A>>
-Synthesis of ethylene oxide chain-containing fluorine monomer (MPOERfA)-
The reaction formula of the synthetic reaction of the ethylene oxide chain-containing fluorine monomer is shown below.
However, in the above reaction formula, the average of n is 8 to 9.

Next, a four-necked flask was charged with 52.13 g of one-terminal methoxypolyethylene glycol (average number of EO: 8 to 9, Uniox M-400, manufactured by NOF CORPORATION) and 0.94 g of boron trifluoride diethyl ether complex. It is. Under a nitrogen stream, 50 g of 3-perfluorohexyl-1,2-epoxypropane was added dropwise at room temperature over 30-40 minutes while paying attention to heat generation. After the completion of dropping, the reaction was continued at room temperature for about 2 hours, and then it was confirmed by gas chromatography (GC) that the peak of 3-perfluorohexyl-1,2-epoxypropane had disappeared. To this, 0.03 g of tertiary butyl catechol was added and well stirred. Further, 14.81 g of triethylamine was added, and 12.04 g of acrylic acid chloride was added dropwise over about 20 minutes while paying attention to heat generation. After the completion of the dropping, the reaction was continued at room temperature for about 2 hours, and then it was confirmed by GC that the peak of acrylic acid chloride had almost disappeared. The product was identified by IR spectrum, 1H-NMR and 19F-NMR spectrum.

-Synthesis of Fluorine-Containing Acrylate Ester Polymer A-
In a 200 mL four-necked flask, 10% by mass of the synthesized MPOERfA monomer, 60% by mass of 2-(perfluorohexyl)ethyl acrylate, polyethylene glycol monoacrylate (EO: 10 mol, NOF Corporation, AE-400). ) 60 g of isopropyl alcohol was charged to a monomer composition of 20% by mass, 5% by mass of 2-hydroxyethyl acrylate, 2.5% by mass of acetoacetoxyethyl methacrylate, and 2.5% by mass of dimethylaminoethyl acrylate. Nitrogen was blown into this for 60 minutes to replace the air in the system with nitrogen. While continuing the nitrogen flow, the internal temperature was raised to 75°C to 80°C, 0.25 g of azobisisobutyronitrile was added, and a polymerization reaction was carried out for 8 hours. When the polymer solution was analyzed by gas chromatography (GC) and gel permeation chromatography, it was confirmed that the peaks derived from the monomer almost disappeared and the peaks derived from the copolymer were generated. The weight average molecular weight of the copolymer was 17,000 (converted to polystyrene). Finally, 0.42 g of acetic acid was added for neutralization, and the mixture was diluted with water to give a 20% by mass solution of the fluorinated acrylate ester copolymer A.

-Production of nozzle plate-
Next, a nozzle substrate made of stainless steel (SUS304) having a length of 34 mm×width of 16 mm and an average thickness of 20 μm was prepared. In the nozzle substrate, nozzle holes having an average hole diameter of 25 μm were formed with four rows of nozzle holes arranged at 320 pieces/row at a pitch of 85 μm (300 dpi) which is the shortest distance between the centers of the nozzle holes. ing.
A 20 mass% solution of the prepared fluorinated acrylate ester polymer A was applied to the surface of the nozzle substrate on the ink ejection side by a dipping method and dried to form an ink repellent film having an average thickness of 50 nm.
As described above, the nozzle plate A of Production Example 101 was produced. At this time, the nozzle holes were masked with a water-soluble resin, and the back surface of the nozzle substrate was masked with tape to form an ink repellent film and then peeled off. Further, the ink repellent film was formed by heating at 120° C. for 1 hour.

(Production Example 102)
<Production of nozzle plate B>
<<Synthesis of Fluorine-Containing Acrylate Ester Polymer B>>
2-Synthesis of Rf epoxy adduct of hydroxyethyl acrylate (HEA) (FAGMA)-
The reaction formula of the synthesis reaction of the Rf epoxy adduct of 2-hydroxyethyl acrylate is shown below.

A 4-necked flask was charged with 20 g of 2-hydroxyethyl acrylate (HEA), 0.61 g of boron trifluoride diethyl ether complex, and 0.026 g of tertiary butyl catechol. 64.83 g of 3-perfluorohexyl-1,2-epoxypropane was added dropwise at room temperature over 30 to 40 minutes while paying attention to heat generation. After the completion of dropping, the reaction was continued at room temperature for about 2 hours, and then it was confirmed by gas chromatography (GC) that the peak of 3-perfluorohexyl-1,2-epoxypropane had disappeared. After the reaction was completed, the reaction product was dissolved in 100 g of 1,1-dichloro-1,2,2,3,3-pentafluoropropane (HCFC225), 100 g of water was further added, and the mixture was washed with a separatory low. , The organic layer was taken out. This washing and liquid separation operation was repeated once again, the organic layer was taken out, 5 g of anhydrous magnesium sulfate was added, and the mixture was dried overnight. HCFC225 was evaporated to obtain an Rf epoxy adduct of HEA (FAGMA). The product was identified by IR spectrum, 1H-NMR and 19F-NMR spectrum. From the results of analysis of the product, 1-mol adduct of 3-perfluorohexyl-1,2-epoxypropane (n=1) is about 64% by mass, 2-mol adduct (n=2) is about 27% by mass, A mixed monomer containing about 9% by mass of the 3 mol adduct was obtained.

-Synthesis of sulfonic acid-containing fluorine monomer-
The reaction formula of the synthesis reaction of the sulfonic acid-containing fluorine monomer is shown below.

30 g of the synthesized Rf epoxy adduct of HEA (FAGMA), 30 g of dichloromethane, 7.8 g of triethylamine, and 0.024 g of hydroquinone monomethyl ether were charged in a four-necked flask. This mixed solution was cooled in an ice bath to 0 to 10°C. A dichloromethane solution of chlorosulfonic acid (7.48 g of chlorosulfonic acid+15 g of dichloromethane) was gradually added dropwise thereto over about 30 minutes while paying attention to heat generation. After completion of the dropping, the reaction was carried out at room temperature for 3 hours. 100 g of water was added to the reaction product, and washing and liquid separation operations were repeated twice. The organic layer was taken out, 5 g of anhydrous magnesium sulfate was added, and the mixture was dried overnight. The product (fluorine monomer containing sulfonic acid) was identified by IR spectrum, 1H-NMR and 19F-NMR spectrum.

-Synthesis of Fluorine-Containing Acrylate Ester Polymer B-
In Production Example 101, the monomer composition was 60% by mass of 2-(perfluorohexyl)ethyl acrylate, 20% by mass of the sulfonic acid group-containing fluorine monomer, polyethylene glycol monoacrylate (EO: 10 mol, NOF Corporation, AE). Fluorine-containing acrylate ester polymer B was synthesized in the same manner as in Production Example 101 except that the amount of (-400) was changed to 17.5% by mass, and the amount of acetoacetoxyethyl methacrylate was changed to 2.5% by mass. The weight average molecular weight of the obtained copolymer was 17,000 (in terms of polystyrene). Finally, 0.42 g of acetic acid was added for neutralization, and the mixture was diluted with water so that a 20 mass% solution of the fluorinated acrylate ester polymer B was obtained.

-Production of nozzle plate-
A 20 mass% solution of the prepared fluorinated acrylate ester polymer B was applied to the surface of the same nozzle substrate as in Production Example 101 on the ink ejection side by a dipping method and dried to give an ink repellent ink having an average thickness of 30 nm. A film was formed.
As described above, the nozzle plate B of Production Example 102 was produced. At this time, the nozzle holes were masked with a water-soluble resin, and the back surface of the nozzle substrate was masked with tape to form an ink-repellent film and then peeled off. Further, the ink repellent film was formed by heating at 120° C. for 1 hour.

(Production Example 103)
<Production of nozzle plate C>
A fluorinated acrylate ester polymer solution (Optool DSX, manufactured by Daikin Industries, Ltd.) was prepared.
By applying the fluorine-containing acrylate ester polymer solution (Optool DSX, manufactured by Daikin Industries, Ltd.) to the surface of the same nozzle substrate as in Production Example 101 on the ink ejection side by a dipping method, and drying, the average thickness is An ink repellent film having a thickness of 20 nm was formed.
As described above, the nozzle plate C of Production Example 103 was produced. At this time, the nozzle holes were masked with a water-soluble resin, and the back surface of the nozzle substrate was masked with tape to form an ink-repellent film and then peeled off. Further, the ink repellent film was formed by heating at 120° C. for 1 hour.

(Production Example 104)
<Production of nozzle plate D>
A silicone resin solution (SR 2441 RESIN, manufactured by Toray Dow Corning Co., Ltd.) was prepared.
The surface of the same nozzle substrate as in Production Example 101 on the ink ejection side was coated with the silicone resin solution by a dipping method and dried to form an ink repellent film having an average thickness of 100 nm. As described above, the nozzle plate D of Production Example 104 was produced. At this time, the nozzle holes were masked with a water-soluble resin, and the back surface of the nozzle substrate was masked with tape to form an ink-repellent film and then peeled off. This was heated and cured at 150° C. for 2 hours in the air to form an ink repellent film.

(Production Example 105)
<Production of nozzle plate E>
As the ink repellent treatment agent, CYTOP CTX-105 (trade name, manufactured by Asahi Glass Co., Ltd.) was used as CT-solv. 100 (manufactured by Asahi Glass Co., Ltd.) and CT-solv. 180 (manufactured by Asahi Glass Co., Ltd.) was mixed at a volume ratio of 1:1 and diluted to 0.2% by mass.
Silicone rubber was placed on the spinner, and this liquid was dropped on 2 mL of silicone rubber. After dropping, the film was rotated on a spinner to form a uniform film. The rotation speed was set to 1st: 1,000 rpm, 5 seconds, 2nd: 3,000 rpm, 20 seconds.
The same nozzle substrate surface as in Production Example 101 was pressed onto the silicone rubber to perform transfer. The number of times was 3, and the pressing pressure was 2 kg/head.
After the completion of transfer, each head was placed in an oven at 150° C. for 2 and a half hours and heat-treated to manufacture a nozzle plate E of Production Example 105.

(Production Example 106)
<Production of nozzle plate F>
As the ink repellent treatment agent, a liquid obtained by diluting a trade name: AF1600 (Teflon (registered trademark) AF, manufactured by DuPont) to 0.5 mass% with a trade name: Fluorinert FC-75 (manufactured by 3M) was used. ..
Silicone rubber was placed on the spinner in the same manner as in Production Example 105, and this liquid was dropped on 2 mL of silicone rubber. After dropping, the film was rotated on a spinner to form a uniform film. The rotation speed was set to 1st: 1,000 rpm, 5 seconds, 2nd: 3,000 rpm, 20 seconds.
The same nozzle substrate surface as in Example 1 was pressed onto the silicone rubber to perform transfer. The number of times was 3, and the pressing pressure was 2 kg/head.
After the completion of transfer, each head was placed in an oven at 165° C. for 2 hours and 30 minutes and heat-treated to manufacture a nozzle plate F of Production Example 106.

-Ink ejection process (printing process)-
Using an inkjet printer (IPSiO GXe-5500, manufactured by Ricoh Co., Ltd.) under an environmental condition adjusted to 23±0.5° C. and 50±5% RH, the piezo element is driven so that the ink ejection amount becomes even. The voltage was changed so that the same amount of ink was attached to the recording medium (Oji Paper Co., Ltd.: OK top coat+_US basis weight 104.7 g/m 2 ).

<Image density>
Using each ink, a chart having the general symbol of JIS X 0208 (1997), 2223 of 64 points created by Microsoft Word 2000 was stamped on MyPaper (manufactured by Ricoh Co., Ltd.), and a spectrodensitometer (X-Rite 939, X- The above symbols were subjected to color measurement by Rite), and the image density of each color was evaluated according to the following criteria. The printing mode used was a driver attached to the printer, which was modified from "plain paper-standard fast" mode to "no color correction". JIS X 0208 (1997), 2223 is a symbol whose outer shape is a regular square and whose entire surface is filled with ink.
〔Evaluation criteria〕
A: Black: 1.25 or more Yellow: 0.80 or more Magenta: 1.00 or more Cyan: 1.05 or more B: Black: 1.20 or more, less than 1.25 Yellow: 0.75 or more, less than 0.80 Magenta: 0.95 or more, less than 1.00 Cyan: 1.00 or more, less than 1.05 C: Black: 1.15 or more, less than 1.20 Yellow: 0.70 or more, less than 0.75 Magenta: 0. 90 or more and less than 0.95 Cyan: 0.95 or more and less than 1.00 D: Black: less than 1.15 Yellow: less than 0.70 Magenta: less than 0.90 Cyan: less than 0.95

<Ink storage stability>
Using the viscometer, the storage stability was calculated according to the following formula from the viscosity before storage and the viscosity measured after storage at 60° C. for 7 days in a sealed container, and evaluated based on the following evaluation criteria.
〔Evaluation criteria〕
A: Within 100±5%.
B: More than 100±5% and less than 10%.
C: 100±10% or more.

<Liquid permeability>
Using a cellulose acetate membrane filter (Advantech Toyo Co., Ltd. _28CP) with a pore size of 0.8 μm, air pressure was set to 1 kgf/cm 2 and pressure filtration was performed. Rate) and the maximum filtration rate, the liquid permeability of the ink was evaluated.
[Evaluation Criteria] Liquid permeability Good_A <------------> D_ Poor A: Attenuation rate is less than 1.5×10 ^-3 /sec and maximum filtration rate is 1.0 g/sec or more. Case B: Attenuation rate is less than 1.5×10 ₋₃ /sec and maximum filtration rate is less than 1.0 g/sec C: Attenuation rate is 1.5×10 ⁻³ /sec or more and 2.5× When it is less than 10 ⁻³ /sec D: When the attenuation rate is 2.5×10 ⁻³ /sec or more

<Discharge stability-1>-Continuous discharge evaluation-
Immediately after passing 1 L of each individually adjusted ink from the ink cartridge of the ink jet printer (IPSiO GXe-5500, manufactured by Ricoh Co., Ltd.) to the ejection head of each color, 80% of the area of the A4 size paper created by Microsoft Word 2000 A continuous 200 sheets of a chart filled with a solid image were printed on MyPaper (manufactured by Ricoh Co., Ltd.), and a nozzle check chart was printed after the printing, and the discharge disturbance of each nozzle was evaluated according to the following criteria.
The print mode was the driver attached to the printer, and the plain paper user setting was changed from "plain paper-standard fast" to "no color correction".
〔Evaluation criteria〕
A: No ejection turbulence B: Some ejection turbulence C: Ejection turbulence or no ejection portion D: Severe ejection turbulence or many nozzles not ejecting

<Discharging stability-2>-Evaluation of ink repellency time of nozzle plate-
In an environment adjusted to a temperature of 23° C.±0.5° C. and a relative humidity of 50%±5%, 50 g of each ink shown in Table 7 was placed in a 50 mL beaker, and an image forming apparatus (IPSiO GXe-5500, manufactured by Ricoh Co., Ltd.) was used. ), the nozzle plate prepared above is sandwiched with tweezers, immersed in ink at a speed of 315 mm/min, and the ink repellency time from the ink repellant film of the nozzle plate (ink shrinkage) when taken out at the same speed Time) was measured and evaluated according to the following criteria.
[Evaluation criteria]
A: Ink repellency time is less than 10 seconds B: Ink repellency time is 10 seconds or more and less than 30 seconds C: Ink repellency time is 30 seconds or more and less than 60 seconds D: Ink repellency time is 60 seconds or more Since the plate is easily wet with ink, it is easy to miss the nozzle in continuous ejection evaluation.

<receding contact angle>
2.0 μL of each ink shown in Tables 4 and 5 was extruded from a syringe equipped with a syringe needle having an inner diameter of 0.37 μm and 0.18 mm onto the surface of the nozzle plate prepared above at 25° C. in a 25° C. environment. The receding contact angle (°) was measured by an automatic contact angle measuring device_DMo-501 (manufactured by Kyowa Interface Science Co., Ltd.).

<Drying property>
Using the image forming apparatus shown in FIG. 1, a chart having the same general symbols as in the case of the image density is printed on Oji Paper Co., Ltd.: OK top coat+rice basis weight 104.7 g/m2, and 100 is printed in the drying step. After being dried by applying warm air of ℃ for 10 seconds, whether or not the ink in the image portion adheres to the transfer roll was visually observed in the dried image portion and evaluated according to the following criteria.
〔Evaluation criteria〕
A: No transfer at all B: Slightly transferred to a level where there is no practical problem C: Transferred D: Violently transferred

<Alcohol resistance (fixability)>
Using each ink, a chart in which a general symbol of JIS X 0208 (1997), 2223 of 64 points created by Microsoft Word 2000 was described was stamped on a PVC media NIJ-PVCM (manufactured by Panacea). The printing mode used was a driver attached to the printer, which was modified from "plain paper-standard clean" mode to "no color correction".
Ethanol (0.5 mL) was included in a cotton swab, and the solid image portion printed as described above was rubbed 10 times, and the image was visually observed and evaluated according to the following criteria.
〔Evaluation criteria〕
A: No change in image area B: Image is readable but slightly scratched C: Image is readable but scratched D: Image area is peeled off and recording medium area is visible

(About Figures 1-3)
1 Recording Medium 2 Ink Discharging Section 3 Conveying Belt 4 Warm Air Drying Device 5 Image Forming Section 6 Drying Processing Section 7 Transfer Roll 400 Image Forming Apparatus 401 Image Forming Apparatus Exterior 401c Device Main Body Cover 404 Cartridge Holder 410 Main Tanks 410k, 410c , 410m, 410y Main tanks for each color of black (K), cyan (C), magenta (M), and yellow (Y) 411 Ink storage section 413 Ink discharge port 414 Storage container case 420 Mechanism section 434 Discharge head 436 Supply tube (About FIGS. 4-9)
1 flow path plate, liquid chamber substrate, flow path member 2 vibration plate member 2a vibration region (diaphragm portion)
2b Island-shaped convex portion 3 Nozzle plate 4 Nozzle hole 5 Nozzle communication passage 6 Liquid chamber, pressurized liquid chamber, pressure chamber, pressurized chamber, flow path 7 Fluid resistance portion 8 Communication portion 10 Common liquid chamber 12 Piezoelectric element, laminated type Piezoelectric element 12A Piezoelectric element pillar, driving piezoelectric element pillar 12B Piezoelectric element pillar, pillar piezoelectric element pillar 13 Base member 15 FPC
16 Drive circuit (driver IC)
17 Frame Member 19 Supply Port 21 Piezoelectric Material Layer 22a, 22b Internal Electrodes 23a, 23b End Face Electrodes (External Electrodes)
31 Nozzle Base Material 31a Ejection Surface 32 Water Repellent Film 33 Ti Layer (Underlayer)
34 ejection surface side of the SiO ₂ film 35 liquid chamber side of the SiO ₂ film 100 piezoelectric actuator unit

JP 2012-241135 JP2012-207202A JP, 2014-94998, A

Claims (21)

In an ink containing water, an organic solvent and polyurethane resin particles, the ink contains a cyclic ester having a structure represented by the following general formula (I), and the ink is allowed to stand for 1 month in a room temperature environment (25±5° C.). An ink in which the content of crystals of the cyclic ester having a particle size of 1 μm or more is less than 4 ppm of the entire ink after storage.
The ink according to claim 1, wherein the polyurethane resin contains a polyurethane resin having a structure represented by the general formula (I). The ink according to claim 1, wherein the ink contains a colorant. The solid content of the polyurethane resin particles is 3% by mass or more in the ink, and the solid content ratio of the colorant and the polyurethane resin particles is 1.0: (2.0 to 11.0). The ink according to item 3. The ink according to claim 3, wherein the colorant is a pigment. The ink according to claim 1, which contains a diol compound and an organic solvent having a solubility parameter (SP value) of 8.9 to 12.0 as the organic solvent. The ink according to claim 1, wherein the ink has a pH of 8.5 or more. The ink according to claim 7, wherein the ink contains a strong basic compound. The ink according to claim 8, wherein the strongly basic compound is sodium hydroxide or potassium hydroxide. The ink according to any one of claims 1 to 9, wherein the ink further contains a polyether-modified siloxane compound as a surfactant. In a method for producing an ink containing water, an organic solvent and polyurethane resin particles, a step of mixing water, an organic solvent and polyurethane resin particles, and heating the mixture obtained by the above step at 40°C or higher and lower than 70°C for 6 hours or longer. The method for producing the ink according to claim 1, further comprising: The ink further contains a colorant, and a step of mixing water, an organic solvent, polyurethane resin particles, and a colorant, and a step of heating the mixture obtained by the step at 40° C. or higher and lower than 70° C. for 6 hours or longer. The method for producing the ink according to claim 11, which has. A printing method comprising a step of printing the ink according to any one of claims 1 to 10 on a substrate. The step of printing by adhering the ink onto a base material is a step of ejecting the ink from an ink ejection head having a nozzle plate for ejecting the ink and adhering the ink onto the base material,
The ink contains water, an organic solvent, polyurethane resin particles, and a cyclic ester having a structure represented by the following general formula (I), and is stored for one month in a room temperature environment (25±5° C.). The printing method according to claim 13, wherein the content of crystals of the cyclic ester having a particle size of 1 μm or more is less than 4 ppm of the entire ink, and the receding contact angle with respect to the nozzle plate is 35° or more.
A printing apparatus comprising: an ink cartridge containing the ink according to any one of claims 1 to 10; and an ejection unit configured to eject the ink. The printing apparatus according to claim 15, further comprising a filter between the ink flow path from the ink cartridge to the ejection unit that ejects ink. The printing apparatus according to claim 15 or 16, wherein the ejection unit that ejects the ink is an ink ejection head having a nozzle plate that ejects the ink, and a receding contact angle of the ink with respect to the nozzle plate is 35° or more. .. The printing device according to claim 17, wherein the nozzle plate has an ink repellent film, and the ink repellent film of the nozzle plate contains a fluorine-containing acrylate ester polymer. 19. The fluorine-containing acrylate ester polymer contains a polymer obtained by polymerizing at least one of a compound represented by the following general formula (II) and a compound represented by the following general formula (III). Printing device.
However, in said general formula (II) and (III), X is a hydrogen atom, a C1-C21 linear or branched alkyl group, a halogen atom, CFX1X2 group (however, X1 and X2 are respectively, Independently a hydrogen atom or a halogen atom), a cyano group, a linear or branched fluoroalkyl group having 1 to 21 carbon atoms, a substituted or unsubstituted benzyl group, and a substituted or unsubstituted phenyl R ₁ is an alkyl group having 1 to 18 carbon atoms, R ₂ is an alkylene group having 2 to 6 carbon atoms, and R ₃ is an alkylene group having 2 to 6 carbon atoms. Yes, Y is an acid group, and Rf is a linear or branched fluoroalkyl group having 1 to 21 carbon atoms. m is 1 to 10, n is 2 to 90, p is 1 to 90, and q is 1 to 10. The fluorine-containing acrylate ester polymer contains a polymer having at least one of a structural unit represented by the following general formula (IV) and a structural unit represented by the following general formula (V). Printing device.
However, in the general formulas (IV) and (V), X represents a hydrogen atom, a linear or branched alkyl group having 1 to 21 carbon atoms, a halogen atom, a CFX1X2 group (provided that X1 and X2 are respectively Independently a hydrogen atom or a halogen atom), a cyano group, a linear or branched fluoroalkyl group having 1 to 21 carbon atoms, a substituted or unsubstituted benzyl group, and a substituted or unsubstituted phenyl R ₁ is an alkyl group having 1 to 18 carbon atoms, R ₂ is an alkylene group having 2 to 6 carbon atoms, and R ₃ is an alkylene group having 2 to 6 carbon atoms. Yes, Y is an acid group, and Rf is a linear or branched fluoroalkyl group having 1 to 21 carbon atoms. m is 1 to 10, n is 2 to 90, p is 1 to 90, and q is 1 to 10. 20. The printing device according to claim 17, wherein the ink-repellent film contains a polymer having a fluorine-containing heterocyclic structure in its main chain.