JP6788221B2 - Ink manufacturing method - Google Patents

Description

The present invention relates to a manufacturing method of the ink.

Compared to other recording methods, the inkjet recording method has become popular because it has the advantages of a simple process, easy full-color printing, and the ability to obtain high-resolution images even with a device with a simple configuration. It is expanding from personal to office applications, commercial printing and industrial printing. In such an inkjet recording method, a water-based ink composition using a water-soluble dye as a coloring material is mainly used, but since it has a drawback of being inferior in water resistance and light resistance, it is water-insoluble instead of the water-soluble dye. The development of pigment inks using the above pigments is underway.

In inkjet printing for office use, plain paper is mainly used as a recording medium, and high image density is required. Generally, when a pigment ink is printed on plain paper, the pigment penetrates into the paper without staying on the paper surface, so that the pigment density on the paper surface becomes low and the image density decreases. If the pigment density in the ink is increased, the image density is increased, but the viscosity of the ink is increased and the ejection stability is lowered.

As a measure against high-speed printing, in order to accelerate the drying speed of the ink adhering to the recording medium, a means for accelerating the drying is taken by adding a penetrant such as a hydrophobic solvent to the ink and allowing the ink to penetrate into the recording medium. This high-speed printing measure is also effective for improving image quality, and beading (integration of ink droplets between adjacent dots on the paper surface) by quickly infiltrating a penetrant such as a hydrophobic solvent into the recording medium. Since bleeding at the color boundary can be suppressed, high dispersion stability is required for inks containing a large amount of hydrophobic solvent.

Against the above background, in the invention described in Patent Document 1, the water-soluble material used as the dispersant is contained in a large amount of a relatively hydrophobic water-soluble organic solvent having a dissolution parameter of 5.0 to 15.0. It prevents the elution of the polymer and achieves both stability and high image density.
Further, in the invention described in Patent Document 2, by increasing the aromatic ring amount of the polymer containing the colorant, high stability and high image quality are achieved even when a penetrant such as alkylene glycol is added.

With conventional inks, the storage stability of magenta inks was not sufficient. In addition, in a method such as a line head printer that can improve the printing speed, in which the nozzle surface of the inkjet head cannot be capped, the ejection droplets may be bent or the ink may be clogged if left for a long time, which is sufficient. Discharge stability could not be ensured.

Therefore, the present invention has been made in view of the current state of the prior art, and an object of the present invention is to provide an ink having excellent storage stability and ejection stability and capable of forming a high-quality image with suppressed beading. ..

In order to solve the above problems, the method for producing an ink of the present invention has the configuration as described below .
C. I. Pigment Red 122, C.I. I. Pigment Red 202, C.I. I. Pigment Red 209, and C.I. I. One or more pigments selected from Pigment Violet 19: quinacridone pigment, synergist with quinacridone skeleton, dispersant with polyoxyethylene structure and solubility parameter of 9.00 (cal / cm ³ ) ^1/2 or more 11.80 (Cal / cm ³ ) A method for producing an ink, which comprises a step of heat-treating a mixture containing an organic solvent of ^1/2 or less using a heater.
The content of the organic solvent with respect to the total amount of the ink is 30% by mass or more and 60% by mass or less, and when the ink is sealed and heated at 80 ° C. for 4 weeks, the viscosity change rate before and after the sealing heating and before and after heating. Both particle size change rates are -5% or more and 1% or less.

According to the present invention, it is possible to provide an ink having excellent storage stability and ejection stability and capable of forming a high-quality image with suppressed beading.

It is a perspective view which shows typically an example of the recording apparatus which concerns on this invention. It is a perspective view which shows typically an example of the ink container which concerns on this invention. It is an external perspective explanatory view of the circulation type liquid discharge head. It is sectional drawing in the direction orthogonal to the nozzle arrangement direction of the head. It is a partial cross-sectional explanatory view of the direction parallel to the nozzle arrangement direction of the head. It is a plane explanatory view of the nozzle plate of the head. It is a plane explanatory view of each member which constitutes the flow path member of the head. It is a plane explanatory view of each member which constitutes the common liquid chamber member of the head. It is a block diagram which shows an example of the liquid circulation system which concerns on this invention. It is a plane explanatory view of the main part of an example of the apparatus which has a circulation type liquid discharge head. It is explanatory drawing of the main part of the apparatus. It is a plane explanatory view of the main part of another example of the liquid discharge unit which concerns on this invention.

Hereinafter, a method for manufacturing an ink according to the present invention, the ink also present invention will relate to the convenience Uehon invention description, a method of manufacturing the ink, the ink container, referring to the drawings as a recording apparatus and a recording method I will explain while. The present invention is not limited to the embodiments shown below, and can be modified within the range conceivable by those skilled in the art, such as other embodiments, additions, modifications, and deletions. However, as long as the action and effect of the present invention are exhibited, it is included in the scope of the present invention.

The ink of the present invention contains an organic solvent having a dissolution parameter of 9.00 or more and 11.80 or less in an amount of 30% by mass or more and 60% by mass or less based on the total amount of the ink. By containing a large amount of the hydrophobic solvent in this way, the penetration rate of the ink on the paper surface can be increased, and the coalescence of ink droplets (beading) between adjacent dots on the paper surface and the bleeding at the color boundary can be suppressed.
Further, the ink of the present invention has a viscosity change rate before and after heating and a particle size change rate before and after heating of -5% or more and 1% or less when the ink is sealed and heated at 80 ° C. for 4 weeks, and is stable in storage. It has excellent properties and discharge stability.
The particle size change rate before and after heating refers to the change rate of 90% cumulative volume particle size (D90) of the solid content in the ink. Further, the rate of change of the 50% cumulative volume particle size (D50) of the solid content in the ink is also preferably −5% or more and 1% or less.
Further, in the present invention, the sealing heating is performed in a state where ink is put in a container, the lid is closed, and the boundary portion between the container and the lid is sealed with a sealing tape to suppress ink volatilization.

The dispersion stability of the pigment, which is a coloring material, is impaired by using an ink containing a large amount of hydrophobic solvent. In particular, the dispersion stability of the quinacridone pigment is significantly deteriorated. However, the ink of the present invention provides high storage stability. The property and discharge stability could be realized. In particular, by selecting pigments, synergists, and dispersants and using heat treatment, even higher storage stability and discharge stability could be achieved. This is because the dispersant can be more strongly adsorbed on the pigment surface by appropriately selecting the pigment, synergist, and dispersant, and by further performing the heat treatment of the present invention, the hydrophobic portion and the hydrophilic portion of the dispersant are three-dimensional. Since the structure can be optimized, high dispersion stability can be realized even in an ink containing a large amount of hydrophobic solvent, which could not be realized by the conventional technique, and an ink having excellent storage stability and ejection stability can be realized.
Hereinafter, the composition of the ink of the present invention will be described in detail.

<Ink>
Hereinafter, the organic solvent, water, coloring material, resin, additive, etc. used for the ink will be described.

<Organic solvent>
The ink of the present invention contains an organic solvent having a dissolution parameter of 9.00 or more and 11.80 or less in an amount of 30% by mass or more and 60% by mass or less based on the total amount of the ink for the purpose of improving the image quality.
When an organic solvent having a solubility parameter smaller than 9.00 is used, the dispersion stability of the quinacridone pigment is impaired because the hydrophobicity of the organic solvent is too strong. On the other hand, when the solubility parameter exceeds 11.80, the hydrophobicity of the organic solvent is inferior, so that the penetration rate of the ink on the paper surface cannot be sufficiently increased, and a defective image such as beading or bleeding may occur. .. Similarly, regarding the amount of the organic solvent, if the content is more than 60% by mass, the dispersion stability may be deteriorated, and if it is less than 30% by mass, a defective image may be generated.

The solubility parameter is a numerical value of the solubility of each other, and is represented by the attractive force between the molecules, that is, the square root of the cohesive energy density CED (Cheese Energy Density). The CED is the amount of energy required to evaporate 1 mL of the product.

The solubility parameter (SP value) is defined by the regular solution theory introduced by Hildebrand and serves as a measure of the solubility of a two-component solution. There are various theories about the calculation method of the dissolution parameter, but the SP value can be calculated by using the following formula (B) by the method of Fedors generally used in the present invention.
Dissolution parameter (SP value) = (CED value) ^1/2 = (E / V) ^1/2 ... Equation (B)
In the above formula (B), E is the molecular aggregation energy (cal / mol), V is the molecular volume (cm ³ / mol), and when the evaporation energy of the atomic group is Δei and the molar volume is Δvi, the following formula ( It is represented by C) and the formula (D).
E = ΣΔei ・ ・ ・ Equation (C)
V = ΣΔvi ・ ・ ・ Equation (D)
As the calculation method, the data of the evaporation energy Δei and the molar volume Δvi of each atomic group, the data described in "Basic Theory of Adhesion" (written by Minoru Imoto, published by Polymer Publishing Association, Chapter 5) is used. be able to. In addition, for those for which a value such as -CF ₃ is not shown, Robert F. et al. Fedors, Polymer Engineering and Science, 1974, Vol14, No. 2,147-154 can be referred to.
The unit of the solubility parameter is (cal / cm ³ ) ^1/2 .

Specific examples of the organic solvent having a dissolution parameter of 9.00 or more and 11.80 or less in the present invention are listed below together with the dissolution parameter.
3-Butoxy-N, N-dimethylpropanamide (9.03), N, N-dimethyl-3-propaneamide (9.08), 3-ethoxy-N, N-dimethylpropanamide (9.13), 3-Methanol-N, N-dimethylpropanamide (9.19), 3-Methanol-3-methylbutanol (9.64), Diethylene glycol monohexyl ether (9.66), Triethylene glycol monobutyl ether (9.77) ), 3-Methyl-1-butanol (7.99), 1-propanol-2-propanol (9.82), diethylene glycol monobutyl ether (9.86), 3-methoxy-1-butanol (9.98), 2-Butanol (9.98), ethylene glycol monobutyl ether (9.99), 1-pentanol (9.99), diethylene glycol monoethyl ether (10.14), 1-methoxy-2-propanol (10.19) ), 1-butanol (10.21), 2-propanol (10.24), 1-propanol (10.52), 1-methyl-2-pyrrolidone (10.84), ethanol (10.96), δ -Valerolactone (11.06), 3-Ethyl-3-oxetanemethanol (11.31), tetraethylene glycol (11.58), γ-butylollactone (11.62), menotar (11.68), 3- Methyl-3-oxetanemethanol (11.79) and the like.

Among these organic solvents, 3-butoxy-N, N-dimethylpropanamide, N, N-dimethyl-3-propaneamide, 3-ethoxy-N from the viewpoint of achieving both storage stability and high-quality image formation. , N-Dimethylpropanamide, 3-methoxy-N, N-dimethylpropanamide, 3-ethyl-3-oxetanemethanol and 3-methyl-3-oxetanmethanol are preferred. Either one type or two or more types can be preferably used. The content of the organic solvent having these solubility parameters of 9.00 or more and 11.80 or less is 30% by mass or more and 60% by mass or less, and more preferably 40% by mass or more and 50% by mass or less with respect to the total amount of ink.

In the ink of the present invention, as an organic solvent having a dissolution parameter of 9.00 or more and 11.80 or less, 3-butoxy-N, N-dimethylpropanamide, N, N-dimethyl-3-propaneamide, 3-ethoxy- An organic solvent selected from N, N-dimethylpropanamide, 3-methoxy-N, N-dimethylpropanamide, 3-ethyl-3-oxetanemethanol and 3-methyl-3-oxetanmethanol is used, and the number of carbon atoms is further increased. It may contain 5 to 7 alkanediols (including cycloalkanediol).
Alcandiol having 5 to 7 carbon atoms is not particularly limited, and specific examples thereof include 1,2-pentanediol, 1,3-pentanediol, 1,4-pentanediol, and 1,5-pentanediol. , 2,3-Pentanediol, 2,4-Pentanediol, 1,2-Cyclopentanediol, 1,3-Cyclopentanediol, 2-Ethyl-1,3-Propanediol, 2-Methyl-1,4- Butanediol, 3-methyl-1,2-butanediol, 3-methyl-1,3-butanediol, 1,2-hexanediol, 1,3-hexanediol, 1,4-hexanediol, 1,5- Hexanediol, 1,6-hexanediol, 2,3-hexanediol, 2,4-hexanediol, 2,5-hexanediol, 3,4-hexanediol, 1,2-cyclohexanediol, 1,3-cyclohexane Diol, 1,4-cyclohexanediol, 4-methyl-1,2-pentanediol, 4-methyl-1,3-pentanediol, 4-methyl-1,4-pentanediol, 2-methyl-1,5- Pentandiol, 2-propyl-1,3-propanediol, 3-methyl-1,2-pentanediol, 3-methyl-1,3-pentanediol, 3-methyl-1,4-pentanediol, 3-methyl -1,5-pentanediol, 3-methyl-2,4-pentanediol, 3-ethyl-1,2-butanediol, 3-ethyl-1,3-butanediol, 3-ethyl-1,4-butane Diole, 2,3-dimethyl-1,2-butanediol, 2,3-dimethyl-1,3-butanediol, 2,3-dimethyl-1,4-butanediol, 2,3-dimethyl-2,3 -Butanediol, 1,2-Heptanediol, 1,3-Heptanediol, 1,4-Heptanediol, 1,5-Heptanediol, 1,6-Heptanediol, 1,7-Heptanediol, 2,3- Heptanediol, 2,4-Heptanediol, 2,5-Heptanediol, 2,6-Heptanediol, 3,4-Heptanediol, 3,5-Heptanediol, 2-methyl-1,2-hexanediol, 2 -Methyl-1,3-hexanediol, 2-methyl-1,4-hexanediol, 2-methyl-1,5-hexanediol, 2-methyl-1,6-hexanediol, 3-methyl-1,2 -Hexanediol, 3-methyl-1,3-he Xandiol, 3-methyl-1,4-hexanediol, 3-methyl-1,5-hexanediol, 3-methyl-1,6-hexanediol, 2,3-dimethyl-1,2-pentanediol, 2 , 3-Diol-1,3-pentanediol, 2,3-dimethyl-1,4-pentanediol, 2,3-dimethyl-1,5-pentanediol, 2,4-dimethyl-1,2-pentanediol , 2,4-Dimethyl-1,3-pentanediol, 2,4-dimethyl-1,4-pentanediol, 2,4-dimethyl-1,5-pentanediol and the like. In particular, alkanediol having 6 carbon atoms is preferably used. By using such an alkane diol, sufficient ejection stability and storage stability are sufficient even when combined with a line head type printer that cannot cap the nozzle surface of the inkjet head or a circulation ejection type head in which the moisture in the ink easily volatilizes. It has become possible to realize sex. It is considered that this is to maintain a good balance with the hydrophobic groups and hydrophilic groups contained in the dispersant, but in particular, by using such an alkanediol, a hydrophilic chain such as a polyoxyethylene structure contained in the dispersant is used. Can be set to an appropriate length, and even when the water volatilizes and the pigment particles become closer to each other, the length can be set so that the hydrophilic chains of the dispersant extending from the pigment surface do not become entangled with each other. It has become possible to achieve both good storage stability and discharge stability over a long period of time.

The content of the alkanediol having 5 to 7 carbon atoms is preferably 5% by mass or more and 30% by mass or less with respect to the total amount of the ink.
The alkanediol having 5 to 7 carbon atoms may have a solubility parameter of 9.00 or more and 11.80 or less, or may be outside the range. When the solubility parameter is 9.00 or more and 11.8 or less, the content is included in the content of the organic solvent whose dissolution parameter is 9.00 or more and 11.80 or less.

The ink of the present invention uses an organic solvent having a solubility parameter of 9.00 or more and 11.80 or less and an alkanediol having 5 to 7 carbon atoms in combination with other organic solvents usually used as the organic solvent of the ink. You may.
The other organic solvent is not particularly limited, and a water-soluble organic solvent can be used. Examples thereof include ethers such as polyhydric alcohols, polyhydric alcohol alkyl ethers and polyhydric alcohol aryl ethers, nitrogen-containing heterocyclic compounds, amides, amines and sulfur-containing compounds.
Specific examples of the water-soluble organic solvent include ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, and 1,4-butane. Diore, 2,3-butanediol, triethylene glycol, polyethylene glycol, polypropylene glycol, glycerin, 1,2,6-hexanetriol, ethyl-1,2,4-butanetriol, 1,2,3-butanetriol, Polyhydric alcohols such as 2,2,4-trimethyl-1,3-pentanediol and petriol, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene Polyhydric alcohol alkyl ethers such as glycol monomethyl ether and propylene glycol monoethyl ether, polyhydric alcohol aryl ethers such as ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether, 2-pyrrolidone, N-methyl-2-pyrrolidone, Nitrogen-containing heterocyclic compounds such as N-hydroxyethyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, ε-caprolactam, γ-butyrolactone, formamide, N-methylformamide, N, N-dimethylformamide, Contains amides such as 3-methoxy-N, N-dimethylpropionamide, 3-butoxy-N, N-dimethylpropionamide, amines such as monoethanolamine, diethanolamine, triethylamine, dimethylsulfoxide, sulfolane, thiodiethanol and the like. Examples include sulfur compounds, propylene carbonate, ethylene carbonate and the like.
It is preferable to use an organic solvent having a boiling point of 250 ° C. or lower because it not only functions as a wetting agent but also has good drying properties.

Polyol compounds having 8 or more carbon atoms and glycol ether compounds are also preferably used. Specific examples of the polyol compound having 8 or more carbon atoms include 2-ethyl-1,3-hexanediol and 2,2,4-trimethyl-1,3-pentanediol.
Specific examples of the glycol ether compound include polyvalent alcohol alkyls such as ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, and propylene glycol monoethyl ether. Ethers: Polyhydric alcohol aryl ethers such as ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether can be mentioned.

The polyol compound having 8 or more carbon atoms and the glycol ether compound can improve the permeability of the ink when paper is used as the recording medium.

The content of the organic solvent in the ink is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 30% by mass or more and 60% by mass or less from the viewpoint of ink drying property and ejection reliability. More preferably, it is 35% by mass or more and 60% by mass or less.

<Water>
The content of water in the ink is not particularly limited and may be appropriately selected depending on the intended purpose, but from the viewpoint of ink drying property and ejection reliability, it is preferably 30% by mass or more and 65% by mass or less, and 35% by mass. % To 55% by mass is more preferable.

<Color material>
In the present invention, a quinacridone pigment is used as the coloring material from the viewpoint of color gamut and weather resistance.
Examples of the quinacridone pigment include quinacridone having or not having a substituent. Examples of the substituent include a methyl group, a chloro group, a methoxy group and the like. Examples of quinacridone pigments include C.I. I. Pigment Red 122 (2,9-dimethylquinacridone), C.I. I. Pigment Red 202 (2,9-dichloroquinacridone), C.I. I. Pigment Red 206, C.I. I. Pigment Red 207, C.I. I. Pigment Red 209 (3,10-dichloroquinacridone), and C.I. I. Pigment Violet 19 (unsubstituted quinacridone), 3,10-dimethylquinacridone, 3,10-dichloroquinacridone, 3,10-dimethoxyquinacridone, 4,11-dimethylquinacridone, 4,11-dichloroquinacridone, 4,11-dimethoxyquinacridone , Quinacridone quinone and the like. At least one of these quinacridone pigments can be used satisfactorily, but from the viewpoint of hue and dispersion stability, C.I. I. Pigment Red 122, C.I. I. Pigment Red 202, C.I. I. Pigment Red 209, C.I. I. Pigment Violet 19 can be used satisfactorily.

The quinacridone pigment in the present invention may be used in combination of two or more depending on the purpose such as expanding the color gamut. When two or more kinds of quinacridone pigments are used, a combination containing at least two kinds from unsubstituted quinacridone, dimethyl quinacridone, and dichloroquinacridone is preferable as a good combination. More specifically, C.I. I. Pigment Red 122, C.I. I. Pigment Red 202, C.I. I. Pigment Red 209, C.I. I. Pigment Violet 19 can be mentioned, and any of these mixtures and solid solutions can be used satisfactorily regardless of the combination form.

Since the quinacridone pigment has anisotropy in its crystal structure, it is difficult to firmly adsorb the dispersant on the entire surface of the pigment, and there is a problem in dispersion stability. In the present invention, even higher storage stability and discharge stability could be realized by using a synergist, a dispersant and a heat treatment. This is because the dispersant can be more strongly adsorbed on the pigment surface by appropriately selecting the pigment, synergist, and dispersant, and by further performing the heat treatment of the present invention, the hydrophobic portion and the hydrophilic portion of the dispersant are three-dimensional. Since the structure can be optimized, high dispersion stability can be realized even in an ink containing a large amount of hydrophobic solvent, which could not be realized by the conventional technique, and an ink having excellent storage stability and ejection stability can be realized.

The content of the quinacridone pigment in the ink is preferably 0.1% by mass or more and 15% by mass or less, more preferably 1% by mass or more and 10% by mass, from the viewpoint of improving image density, good fixability and ejection stability. It is as follows.

There are known coloring materials that can be used in addition to the above pigments. The coloring material is not particularly limited, and pigments and dyes can be used. As the pigment, an inorganic pigment or an organic pigment can be used. These may be used alone or in combination of two or more. Moreover, you may use a mixed crystal.

As the pigment, for example, black pigment, yellow pigment, magenta pigment, cyan pigment, white pigment, green pigment, orange pigment, glossy color pigment such as gold or silver, metallic pigment and the like can be used. As inorganic pigments, in addition to titanium oxide, iron oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, cadmium red, and chrome yellow, carbon black produced by known methods such as contact method, furnace method, and thermal method. Can be used.

Examples of organic pigments include azo pigments, polycyclic pigments (for example, phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, dioxazine pigments, indigo pigments, thioindigo pigments, isoindolinone pigments, quinofuralone pigments, etc.) and dye chelates. (For example, basic dye type chelate, acid dye type chelate, etc.), nitro pigment, nitroso pigment, aniline black and the like can be used.

Among these pigments, those having a good affinity with a solvent are preferably used. In addition, resin hollow particles and inorganic hollow particles can also be used.

As a specific example of the pigment, for black, carbon black (CI pigment black 7) such as furnace black, lamp black, acetylene black, channel black, or copper, iron (CI pigment black 11) , Metals such as titanium oxide, and organic pigments such as aniline black (CI pigment black 1).
For color, 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 , 108, 109, 110, 117, 120, 138, 150, 153, 155, 180, 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 Cadmium 6B), 60: 1, 63: 1, 63: 2, 64: 1, 81, 83, 88, 101 (Magenta), 104, 105, 106, 108 ( Cadmium Red), 112, 114, 122 (Quinacridone Magenta), 123, 146, 149, 166, 168, 170, 172, 177, 178, 179, 184, 185, 190, 193, 202, 207, 208, 209, 213, 219, 224, 254, 264, 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, 15: 4 (phthalocyanine blue), 16, 17: 1, 56, 60, 63, C.I. I. Pigment Greens 1, 4, 7, 8, 10, 17, 18, 36, etc.

The dye is not particularly limited, and acid dyes, direct dyes, reactive dyes, and basic dyes can be used, and one type may be used alone or two or more types may be used in combination.
As the dye, for example, C.I. I. Acid Yellow 17, 23, 42, 44, 79, 142, C.I. I. Acid Red 52,80,82,249,254,289, C.I. I. Acid Blue 9,45,249, C.I. I. Acid Black 1,2,24,94, C.I. I. Hood Black 1, 2, C.I. I. Direct Yellow 1,12,24,33,50,55,58,86,132,142,144,173, C.I. I. Direct Red 1,4,9,80,81,225,227, C.I. I. Direct Blue 1,2,15,71,86,87,98,165,199,202, C.I. I. Dilekdo Black 19, 38, 51, 71, 154, 168, 171, 195, C.I. I. Reactive Red 14, 32, 55, 79, 249, C.I. I. Reactive Black 3, 4, 35 can be mentioned.

The content of the coloring material in the ink is preferably 0.1% by mass or more and 15% by mass or less, more preferably 1% by mass or more and 10% by mass, from the viewpoint of improving image density, good fixability and ejection stability. It is as follows.

To disperse the pigment in the ink, a method of introducing a hydrophilic functional group into the pigment to obtain a self-dispersing pigment, a method of coating the surface of the pigment with a resin and dispersing it, a method of dispersing using a dispersant, etc. Can be mentioned. As a method of introducing a hydrophilic functional group into a pigment to obtain a self-dispersing pigment, for example, a self-dispersing pigment in which a functional group such as a sulfone group or a carboxyl group is added to the pigment so that it can be dispersed in water can be used. Such a self-dispersing pigment can be used alone, but it is also possible to use a pigment having no hydrophilic functional group introduced in combination with a synergist, and the quinacridone sulfonic acid is used for the quinacridone pigment of the present invention. The derivative can be satisfactorily used as a synergist.

Synagisto is a pigment derivative in which polar groups such as acidic groups and basic groups are introduced into the pigment skeleton, and can be adsorbed on the pigment surface by π-π interaction or hydrophobic interaction to modify the pigment surface to be acidic or basic. .. As a result, the electrostatic repulsion between the pigment particles becomes large, so that the dispersion stability can be improved, and the electrostatic adsorption force also increases with the hydrophilic parts such as the acidic group and the basic group introduced into the dispersant. As a result, the dispersant can be firmly adsorbed on the pigment surface via the synergist, and the dispersion stability is enhanced in terms of steric hindrance in addition to electrostatic repulsion between the pigment particles. Examples of the pigment skeleton used as a synergist include azo pigments, phthalocyanine pigments, quinacridone pigments, perylene pigments, isoindrin pigments, benzimidazolone pigments, pyranthron pigments, thioindigo pigments, and quinophthalone pigments.

Examples of the polar group include an alkylamino group, a carboxyl group, a sulfonic acid group, a phthalimide group and the like. Known synergists in the present invention (for example, Solspurse 5000, Solsperse 12000, Solsperse 22000 manufactured by Lubrizol Japan, Inc.) can be effectively used, but in terms of improving the adsorption power with the quinacridone pigment used in the present invention. Quinacridone pigment is a good pigment skeleton for synergists. Further, as the polar group to be introduced into the synergist, a sulfonic acid group can be preferably used from the viewpoint of ease of introduction, and as the synergist, a sulfonic acid derivative of quinacridone is particularly preferably used.

The content of synergist in the ink is preferably 0.1% by mass or more and 10% by mass or less, more preferably 1% by mass or more and 5% by mass or less, from the viewpoint of good dispersion stability, color gamut and color reproducibility. is there.

As a method of coating the surface of the pigment with a resin and dispersing it, a method in which the pigment is encapsulated in microcapsules and can be dispersed in water can be used. This can be rephrased as a resin coating pigment. In this case, it is not necessary that all the pigments blended in the ink are coated with the resin, and the uncoated pigments and the partially coated pigments are dispersed in the ink as long as the effects of the present invention are not impaired. You may be.
Examples of the method of dispersing using a dispersant include a method of dispersing using a known low molecular weight dispersant or high molecular weight dispersant, and the polymer dispersant is preferable from the viewpoint of dispersion stability.

Examples of the polymer dispersant include DISPERBYK-102, DISPERBYK-103, DISPERBYK-106, DISPERBYK-107, DISPERBYK-108, DISPERBYK-109, DISPERBYK-110, DISPERBYK-111, DISPERBYK-115, DISPERBYK-118, DISPERBYK-118. DISPERBYK-142, DISPERBYK-145, DISPERBYK-161, DISPERBYK-162, DISPERBYK-163, DISPERBYK-164, DISPERBYK-166, DISPERBYK-167, DISPERBYK-168, DISPERBYK-170, DISPERBYK-170, DISPERBYK-170, DISPERBYK-170 181 、 DISPERBYK-182, DISPERBYK-184, DISPERBYK-185, DISPERBYK-187, DISPERBYK-190, DISPERBYK-191, DISPERBYK-192, DISPERBYK-193, DISPERBYK-194N, DISPERBYK-199, DISPERBYK-199, DISPERBYK-199 DISPERBYK-2008, DISPERBYK-2009, DISPERBYK-2010, DISPERBYK-2012, DISPERBYK-2013, DISPERBYK-2015, DISPERBYK-2022, DISPERBYK-2025, DISPERBYK-2026, DISPERBYK-2026, DISPERBYK-2026, DISPERBYK-2026, DISPERBYK-2026, DISPERBYK-2026 2055, DISPERBYK-2063, DISPERBYK-2064, DISPERBYK-2200, BYKJET-9131, BYKJET-9132, BYKJET-9133, BYKJET-9142, BYKJET-9150, BYKJET-9152, BYKJET-9152, BYKJET-9152, BYKJET-9152, BYKJET-9152 , Dispex AA 4040 NS (old Dispex A40), Dispex AA 4140 NS, Dispex AA 4144 (old Hydropalt 44), Dispex CX 4240 (old Dispex GA4) 0), Dispex CX 4320 (old Pigment Disperser MD 20), Dispex CX 4325 (old Dispex HDN), Dispex CX 4340 (old Dispex G40), Dispex CX 4910 (old Displex G40), Dispex CX 4910 (old Dispex HDN), Dispex CX 4340 (old Dispex G40), Dispex CX 4910 (old Dispex HDN) , Dispex Ultra FA 4420 (old Efka 6220), Dispex Ultra FA 4425 (old Efka 6225), Dispex Ultra FA 4431 (old Efka 6230), Dispex Ultra-Ultra ), Dispex Ultra PA 4501 (old Efka 1501), Dispex Ultra PA 4503 (old Efka 1503), Dispex Ultra PA 4510 (old Efka 4510), Dispex Ultra 50 ol45 Efka 45ol45 Oldla 45 Efka 4510 (old Efka 4510), Dispex Ultra 50 ), Dispex Ultra PA 4560 (old Efka 4560), Dispex Ultra PA 4570 (old Efka 4570), Dispex Ultra PA 4580 (old Efka 4580), Dispex UltraP a4 50 (old Efka 4580), Dispex Ultra PA 4580 (old Efka 4580), Dispex Ultra PA 4580 (old Efka) ), Dispex Ultra PX 4585 (old Efka 4585) (all manufactured by BASF) and the like.

These may be used alone or in combination of two or more. Further, from the viewpoint of dispersion stability, those having a polyoxyethylene structure are preferable. Further, these dispersion methods can be used in combination, and from the viewpoint of dispersion stability, a method of dispersing a pigment having a hydrophilic functional group introduced using a dispersant and a method of dispersing a pigment having no hydrophilic functional group have not been introduced. A method of dispersing the pigment and the synergist using a dispersant is preferable.

The mass ratio of the pigment constituting the ink of the present invention, the synergist, and the dispersant is preferably in the following range from the viewpoint of the ability of the synergist and the dispersant to adsorb to the pigment. That is, the mass ratio of pigment: synergist: dispersant is preferably 70 to 100 / 0.1 to 20/5 to 100, more preferably 75 to 95 / 0.5 to 15 / 7.5 to 75. More preferably, it is 80 to 90/1 to 10/10 to 50.

The ink of the present invention can be obtained by a production method comprising a step of heat-treating a raw material mixture of an ink containing a quinacridone pigment and an organic solvent having a dissolution parameter of 9.00 or more and 11.80 or less. Although a conventional method using various heaters or the like can be used for the heat treatment, it is preferable to perform the heat treatment in a sealed state in which ink volatilization is suppressed from the viewpoint of composition variation and dispersion stability.
In the present invention, by using a synergist and heat treatment, the quinacridone pigment is dispersed even in an ink containing a large amount of an organic solvent having a dissolution parameter of 9.00 or more and 11.80 or less, which is 30 to 60% by mass with respect to the total amount of the ink. Increases stability. As the dispersant used here, a polymer dispersant having a hydrophilic moiety can be preferably used, and one having a polyoxyethylene structure as the hydrophilic moiety is preferable. The dispersant having such a hydrophilic portion can optimize the three-dimensional structure of the hydrophobic portion and the hydrophilic portion of the dispersant by the heat treatment in the present invention, and particularly for the dispersant in which the hydrophilic portion has a polyoxyethylene structure. The hydrophilicity of the polyoxyethylene structural portion is reduced by the heat treatment, but the length of the hydrophilic chain is appropriately shortened, so that the interaction between the dispersants adsorbed on the surface of the quinacridone pigment can be reduced. High dispersion stability can be achieved.

It is possible to obtain ink by mixing a material such as water or an organic solvent with a coloring material. It is also possible to produce an ink by mixing a material such as water or an organic solvent with a pigment dispersion obtained by mixing a pigment and other water or a dispersant. The pigment dispersion is obtained by dispersing water, a pigment, a pigment dispersant, and other components as necessary, and adjusting the particle size. It is preferable to use a disperser for dispersion. The particle size of the pigment in the pigment dispersion is not particularly limited, but the maximum frequency in terms of number is 20 nm or more and 500 nm because the dispersion stability of the pigment is good and the image quality such as ejection stability and image density is also high. The following is preferable, and more preferably 20 nm or more and 150 nm or less.

The particle size of the pigment can be measured using a particle size analyzer (Nanotrack Wave-UT151, manufactured by Microtrac Bell Co., Ltd.). The content of the pigment in the pigment dispersion is not particularly limited and may be appropriately selected depending on the intended purpose. However, from the viewpoint of obtaining good ejection stability and increasing the image density, 0.1 mass is used. % Or more and 50% by mass or less are preferable, and 0.1% by mass or more and 30% by mass or less are more preferable.

It is preferable that the pigment dispersion is degassed by filtering coarse particles with a filter, a centrifuge, or the like, if necessary. Further, the ink of the present invention is preferably heat-treated for the purpose of stabilizing dispersion. The heat treatment conditions need to be appropriately controlled depending on the material used for the ink, but the heat treatment temperature in the heat treatment is 25 ° C. to 100 ° C., more preferably 40 to 70 ° C. The heat treatment time is several minutes to 10 days, more preferably 1 hour to 1 day. By performing such a heat treatment, the physical properties of the ink can be further stabilized.

<Resin>
The type of resin contained in the ink is not particularly limited and may be appropriately selected depending on the intended purpose. For example, urethane resin, polyester resin, acrylic resin, vinyl acetate resin, styrene resin, butadiene resin, etc. Examples thereof include resins, styrene-butadiene resins, vinyl chloride resins, acrylic styrene resins, and acrylic silicone resins.
Resin particles made of these resins may be used. It is possible to obtain ink by mixing resin particles with a material such as a coloring material or an organic solvent in the state of a resin emulsion in which water is dispersed as a dispersion medium. As the resin particles, those synthesized as appropriate may be used, or commercially available products may be used. Further, these may be used alone or in combination of two or more kinds of resin particles.

The volume average particle diameter of the resin particles is not particularly limited and may be appropriately selected depending on the intended purpose. However, from the viewpoint of obtaining good fixability and high image hardness, 10 nm or more and 1,000 nm or less are preferable. More than 200 nm is more preferable, and 10 nm or more and 100 nm or less is particularly preferable.
The volume average particle size can be measured using, for example, a particle size analyzer (Nanotrack Wave-UT151, manufactured by Microtrac Bell Co., Ltd.).

The content of the resin is not particularly limited and may be appropriately selected depending on the intended purpose. However, from the viewpoint of fixability and storage stability of the ink, 1% by mass or more and 30% by mass or less with respect to the total amount of the ink. Is preferable, and 5% by mass or more and 20% by mass or less is more preferable.

The particle size of the solid content in the ink is not particularly limited and can be appropriately selected according to the purpose, but from the viewpoint of improving image quality such as ejection stability and image density, the maximum frequency in terms of the maximum number of inks. Is preferably 20 nm or more and 1000 nm or less, and more preferably 20 nm or more and 150 nm or less. The solid content includes resin particles, pigment particles, and the like. The particle size can be measured using a particle size analyzer (Nanotrack Wave-UT151, manufactured by Microtrac Bell Co., Ltd.).

<Additives>
If necessary, a surfactant, a defoaming agent, an antiseptic / antifungal agent, a rust preventive, a pH adjuster, or the like may be added to the ink.

<Surfactant>
As the surfactant, any of a silicone-based surfactant, a fluorine-based surfactant, an amphoteric surfactant, a nonionic surfactant, and an anionic surfactant can be used.
The silicone-based surfactant is not particularly limited and may be appropriately selected depending on the intended purpose.
Among them, those that do not decompose even at high pH are preferable, and examples thereof include side chain modified polydimethylsiloxane, double-ended modified polydimethylsiloxane, single-ended modified polydimethylsiloxane, and side chain double-ended modified polydimethylsiloxane. Those having an oxyethylene group and a polyoxyethylene polyoxypropylene group are particularly preferable because they exhibit good properties as an aqueous surfactant. Further, as the silicone-based surfactant, a polyether-modified silicone-based surfactant can also be used, and examples thereof include a compound in which a polyalkylene oxide structure is introduced into the Si portion side chain of dimethylsiloxane.
As the fluorine-based surfactant, for example, a perfluoroalkyl sulfonic acid compound, a perfluoroalkyl carboxylic acid compound, a perfluoroalkyl phosphate ester compound, a perfluoroalkyl ethylene oxide adduct, and a perfluoroalkyl ether group are contained in a side chain. A polyoxyalkylene ether polymer compound is particularly preferable because it has a low foaming property. Examples of the perfluoroalkyl sulfonic acid compound include perfluoroalkyl sulfonic acid and perfluoroalkyl sulfonic acid salt. Examples of the perfluoroalkylcarboxylic acid compound include perfluoroalkylcarboxylic acid and perfluoroalkylcarboxylic acid salt. The polyoxyalkylene ether polymer compound having a perfluoroalkyl ether group in the side chain includes a sulfate ester salt of a polyoxyalkylene ether polymer having a perfluoroalkyl ether group in the side chain and a perfluoroalkyl ether group in the side chain. Examples thereof include salts of polyoxyalkylene ether polymers. The counterions of the salts in these fluorine-based surfactants are Li, Na, K, NH ₄ , NH ₃ CH ₂ CH ₂ OH, NH ₂ (CH ₂ CH ₂ OH) ₂ , NH (CH ₂ CH ₂ OH). ₃ etc. can be mentioned.
Examples of the amphoteric surfactant include laurylaminopropionate, lauryl dimethyl betaine, stearyl dimethyl betaine, and lauryl dihydroxyethyl betaine.
Examples of the nonionic surfactant include polyoxyethylene alkylphenyl ether, polyoxyethylene alkyl ester, polyoxyethylene alkyl amine, polyoxyethylene alkyl amide, polyoxyethylene propylene block polymer, sorbitan fatty acid ester, and polyoxyethylene sorbitan. Examples thereof include ethylene oxide adducts of fatty acid esters and acetylene alcohols.
Examples of the anionic surfactant include polyoxyethylene alkyl ether acetate, dodecylbenzene sulfonate, lauryl salt, polyoxyethylene alkyl ether sulfate salt and the like.
These may be used alone or in combination of two or more.

（但し、一般式（Ｓ−１）式中、ｍ、ｎ、ａ、及びｂは、それぞれ独立に、整数を表わし、Ｒは、アルキレン基を表し、Ｒ’は、アルキル基を表す。）
上記のポリエーテル変性シリコーン系界面活性剤としては、市販品を用いることができ、例えば、ＫＦ−６１８、ＫＦ−６４２、ＫＦ−６４３（信越化学工業株式会社）、ＥＭＡＬＥＸ−ＳＳ−５６０２、ＳＳ−１９０６ＥＸ（日本エマルジョン株式会社）、ＦＺ−２１０５、ＦＺ−２１１８、ＦＺ−２１５４、ＦＺ−２１６１、ＦＺ−２１６２、ＦＺ−２１６３、ＦＺ−２１６４（東レ・ダウコーニング・シリコーン株式会社）、ＢＹＫ−３３、ＢＹＫ−３８７（ビックケミー株式会社）、ＴＳＦ４４４０、ＴＳＦ４４５２、ＴＳＦ４４５３（東芝シリコン株式会社）などが挙げられる。 The silicone-based surfactant is not particularly limited and may be appropriately selected depending on the intended purpose. For example, side chain-modified polydimethylsiloxane, double-ended modified polydimethylsiloxane, one-ended modified polydimethylsiloxane, side. Examples thereof include polydimethylsiloxane modified at both ends of the chain, and a polyether-modified silicone-based surfactant having a polyoxyethylene group and a polyoxyethylene polyoxypropylene group as modifying groups exhibits good properties as an aqueous surfactant, and is particularly effective. preferable.
As such a surfactant, an appropriately synthesized one may be used, or a commercially available product may be used. As commercially available products, for example, they can be obtained from Big Chemie Co., Ltd., Shin-Etsu Chemical Co., Ltd., Toray Dow Corning Silicone Co., Ltd., Nippon Emulsion Co., Ltd., Kyoeisha Chemical Co., Ltd. and the like.
The above-mentioned polyether-modified silicone-based surfactant is not particularly limited and may be appropriately selected depending on the intended purpose. For example, the polyalkylene oxide structure represented by the general formula (S-1) is dimethylpoly. Examples thereof include those introduced into the Si part side chain of siloxane.

(However, in the general formula (S-1), m, n, a, and b each independently represent an integer, R represents an alkylene group, and R'represents an alkyl group.)
Commercially available products can be used as the above-mentioned polyether-modified silicone-based surfactant, for example, KF-618, KF-642, KF-643 (Shin-Etsu Chemical Co., Ltd.), EMALEX-SS-5602, SS- 1906EX (Nippon Emulsion Co., Ltd.), FZ-2105, FZ-2118, FZ-2154, FZ-2161, FZ-2162, FZ-2163, FZ-2164 (Toray Dow Corning Silicone Co., Ltd.), BYK-33, BYK-387 (Big Chemie Co., Ltd.), TSF4440, TSF4452, TSF4453 (Toshiba Silicon Co., Ltd.) and the like can be mentioned.

上記一般式（Ｆ−１）で表される化合物において、水溶性を付与するためにｍは０〜１０の整数が好ましく、ｎは０〜４０の整数が好ましい。
一般式（Ｆ−２）
Ｃ_nＦ_2n+1−ＣＨ₂ＣＨ(ＯＨ)ＣＨ₂−Ｏ−(ＣＨ₂ＣＨ₂Ｏ)_a−Ｙ
上記一般式（Ｆ−２）で表される化合物において、ＹはＨ、又はＣ_mＦ_2m+1でｍは１〜６の整数、又はＣＨ₂ＣＨ(ＯＨ)ＣＨ₂−Ｃ_ｍＦ_2ｍ+1でｍは４〜６の整数、又はＣ_pＨ_2p+1でｐは１〜１９の整数である。ｎは１〜６の整数である。ａは４〜１４の整数である。
上記のフッ素系界面活性剤としては市販品を使用してもよい。
この市販品としては、例えば、サーフロンＳ−１１１、Ｓ−１１２、Ｓ−１１３、Ｓ−１２１、Ｓ−１３１、Ｓ−１３２、Ｓ−１４１、Ｓ−１４５（いずれも、旭硝子株式会社製）；フルラードＦＣ−９３、ＦＣ−９５、ＦＣ−９８、ＦＣ−１２９、ＦＣ−１３５、ＦＣ−１７０Ｃ、ＦＣ−４３０、ＦＣ−４３１（いずれも、住友スリーエム株式会社製）；メガファックＦ−４７０、Ｆ−１４０５、Ｆ−４７４（いずれも、大日本インキ化学工業株式会社製）；ゾニール（Ｚｏｎｙｌ）ＴＢＳ、ＦＳＰ、ＦＳＡ、ＦＳＮ−１００、ＦＳＮ、ＦＳＯ−１００、ＦＳＯ、ＦＳ−３００、ＵＲ、キャプストーンＦＳ−３０、ＦＳ−３１、ＦＳ−３１００、ＦＳ−３４、ＦＳ−３５（いずれも、Ｃｈｅｍｏｕｒｓ社製）；ＦＴ−１１０、ＦＴ−２５０、ＦＴ−２５１、ＦＴ−４００Ｓ、ＦＴ−１５０、ＦＴ−４００ＳＷ（いずれも、株式会社ネオス社製）、ポリフォックスＰＦ−１３６Ａ，ＰＦ−１５６Ａ、ＰＦ−１５１Ｎ、ＰＦ−１５４、ＰＦ−１５９（オムノバ社製）、ユニダインＤＳＮ-４０３Ｎ（ダイキン工業株式会社製）などが挙げられ、これらの中でも、良好な印字品質、特に発色性、紙に対する浸透性、濡れ性、均染性が著しく向上する点から、Ｃｈｅｍｏｕｒｓ社製のＦＳ−３１００、ＦＳ−３４、ＦＳ−３００、株式会社ネオス製のＦＴ−１１０、ＦＴ−２５０、ＦＴ−２５１、ＦＴ−４００Ｓ、ＦＴ−１５０、ＦＴ−４００ＳＷ、オムノバ社製のポリフォックスＰＦ−１５１Ｎ及びダイキン工業株式会社製のユニダインＤＳＮ-４０３Ｎが特に好ましい。 As the fluorine-based surfactant, a compound having 2 to 16 carbon atoms substituted with fluorine is preferable, and a compound having 4 to 16 carbon atoms substituted with fluorine is more preferable.
Examples of the fluorine-based surfactant include a perfluoroalkyl phosphate compound, a perfluoroalkylethylene oxide adduct, and a polyoxyalkylene ether polymer compound having a perfluoroalkyl ether group in the side chain.
Among these, polyoxyalkylene ether polymer compounds having a perfluoroalkyl ether group in the side chain are preferable because they have low foaming property, and are particularly fluorine-based compounds represented by the general formulas (F-1) and (F-2). Surfactants are preferred.

In the compound represented by the general formula (F-1), m is preferably an integer of 0 to 10, and n is preferably an integer of 0 to 40 in order to impart water solubility.
General formula (F-2)
C _n F _{2n + 1} −CH ₂ CH (OH) CH ₂ −O− (CH ₂ CH ₂ O) _a −Y
In the compound represented by the above general formula (F-2), Y is H, or C _m F _{2 m + 1} , and m is an integer of 1 to 6, or CH ₂ CH (OH) CH _2- C _m F _{2 m +. At 1} , m is an integer of 4 to 6, or C _p H _{2p + 1} and p is an integer of 1 to 19. n is an integer of 1-6. a is an integer of 4 to 14.
Commercially available products may be used as the above-mentioned fluorine-based surfactant.
Examples of this commercially available product include Surflon S-111, S-112, S-113, S-121, S-131, S-132, S-141, and S-145 (all manufactured by Asahi Glass Co., Ltd.); Full Lard FC-93, FC-95, FC-98, FC-129, FC-135, FC-170C, FC-430, FC-431 (all manufactured by Sumitomo 3M Co., Ltd.); Megafuck F-470, F -1405, F-474 (all manufactured by Dainippon Ink and Chemicals Co., Ltd.); Zonyl TBS, FSP, FSA, FSN-100, FSN, FSO-100, FSO, FS-300, UR, Capstone FS-30, FS-31, FS-3100, FS-34, FS-35 (all manufactured by The Chemours Company); FT-110, FT-250, FT-251, FT-400S, FT-150, FT- 400SW (all manufactured by Neos Co., Ltd.), Polyfox PF-136A, PF-156A, PF-151N, PF-154, PF-159 (manufactured by Omniova), Unidyne DSN-403N (manufactured by Daikin Industries, Ltd.) Among these, FS-3100, FS-34, FS- of Chemours Co., Ltd., from the viewpoint of remarkably improving good print quality, particularly color development, permeability to paper, wettability, and leveling property. 300, FT-110, FT-250, FT-251, FT-400S, FT-150, FT-400SW manufactured by Neos Co., Ltd., Polyfox PF-151N manufactured by Omninova, and Unidyne DSN-manufactured by Daikin Industries, Ltd. 403N is particularly preferable.

The content of the surfactant in the ink is not particularly limited and may be appropriately selected depending on the intended purpose. However, 0.001 mass is obtained from the viewpoint of excellent wettability and ejection stability and improvement in image quality. % Or more and 5% by mass or less are preferable, and 0.05% by mass or more and 5% by mass or less are more preferable.

<Defoamer>
The defoaming agent is not particularly limited, and examples thereof include a silicone-based defoaming agent, a polyether-based defoaming agent, and a fatty acid ester-based defoaming agent. These may be used alone or in combination of two or more. Among these, a silicone-based defoaming agent is preferable because it has an excellent defoaming effect.

<Preservatives and fungicides>
The antiseptic and antifungal agent is not particularly limited, and examples thereof include 1,2-benzisothiazolin-3-one.

<Rust inhibitor>
The rust preventive is not particularly limited, and examples thereof include acidic sulfites and sodium thiosulfate.

<pH adjuster>
The pH adjusting agent is not particularly limited as long as the pH can be adjusted to 7 or more, and examples thereof include amines such as diethanolamine and triethanolamine.

The physical properties of the ink are not particularly limited and may be appropriately selected depending on the intended purpose. For example, the viscosity, surface tension, pH and the like are preferably in the following ranges.
The viscosity of the ink at 25 ° C. is preferably 5 mPa · s or more and 30 mPa · s or less, preferably 5 mPa · s or more and 25 mPa · s or less, from the viewpoint of improving the print density and character quality and obtaining good ejection properties. More preferred. Here, for the viscosity, for example, a rotary viscometer (RE-80L manufactured by Toki Sangyo Co., Ltd.) can be used. As the measurement conditions, it is possible to measure at 25 ° C. with a standard cone rotor (1 ° 34'x R24), a sample liquid volume of 1.2 mL, a rotation speed of 50 rpm, and 3 minutes.
The surface tension of the ink is preferably 35 mN / m or less, more preferably 32 mN / m or less at 25 ° C. from the viewpoint that the ink is preferably leveled on the recording medium and the drying time of the ink is shortened.
The pH of the ink is preferably 7 to 12, and more preferably 8 to 11 from the viewpoint of preventing corrosion of the metal member in contact with the liquid.

<Ink container>
The ink container of the present invention is an ink container provided with an ink accommodating portion for accommodating ink, and the ink contained in the ink accommodating portion is the ink of the present invention. The ink is contained in a container and further has other members appropriately selected as needed.
The container is not particularly limited, and its shape, structure, size, material, etc. can be appropriately selected according to the purpose. For example, an ink container formed of an aluminum laminate film, a resin film, or the like can be used. At least those having, for example, a main tank having an ink accommodating portion, an ink cartridge, and the like are suitable.

<Recording medium>
The recording medium is not particularly limited, and plain paper, glossy paper, special paper, cloth, or the like can be used, but good image formation can be achieved even if a non-permeable base material is used.
The non-permeable base material is a base material having a surface having low water permeability and low absorbability, and includes a material that does not open to the outside even if there are many cavities inside, and more quantitatively. , A base material having a water absorption amount of 10 mL / m ² or less from the start of contact to 30 msec ^1/2 in the Bristow method.
As the non-permeable substrate, for example, a plastic film such as a vinyl chloride resin film, a polyethylene terephthalate (PET) film, polypropylene, polyethylene, or a polycarbonate film can be preferably used.
The recording medium is not limited to that used as a general recording medium, and wallpaper, floor materials, building materials such as tiles, cloth for clothing such as T-shirts, textiles, leather and the like can be appropriately used. Further, ceramics, glass, metal, or the like can be used by adjusting the configuration of the path for transporting the recording medium.

<Recorded material>
The ink recording material of the present invention comprises an image formed by using the ink of the present invention on a recording medium.
It can be recorded by an inkjet recording device and an inkjet recording method to obtain a recorded material.

<Recording device, recording method>
The ink of the present invention can be suitably used for various recording devices by an inkjet recording method, for example, a printer, a facsimile device, a copying device, a printer / fax / copier multifunction device, a three-dimensional modeling device, and the like.
In the present invention, the recording device and the recording method are devices capable of ejecting ink, various processing liquids, and the like to a recording medium, and a method of recording using the device. The recording medium means a medium to which ink and various treatment liquids can adhere even temporarily.
The recording apparatus of the present invention has an ink ejection means for ejecting the ink of the present invention from an ejection head and recording information or an image on a recording medium.
The recording method of the present invention includes an ink ejection step of applying a stimulus to the ink of the present invention via an ink ejection means, ejecting the ink from an ejection head, and recording information or an image on a recording medium.
This recording device can include not only a head portion that ejects ink, but also means related to feeding, transporting, and discharging paper of a recording medium, and other devices called pretreatment devices and posttreatment devices. ..

The recording device and recording method may include 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 print surface and the back surface of the recording medium. The heating means and the drying means are not particularly limited, but for example, a hot air heater and 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 significant images such as characters and figures are visualized by ink. For example, those that form patterns such as geometric patterns and those that form a three-dimensional image are also included.
Further, unless otherwise specified, the recording device includes both a serial type device that moves the discharge head and a line type device that does not move the discharge head, and the discharge head circulates liquids in a plurality of individual liquid chambers. Both a circulation type discharge head and a non-circulation type discharge head can be used.
When combined with a circulation type ejection head aiming at both high image quality and high productivity, the ink is circulated under negative pressure in the circulation tank, so the ink has a hydrophobic composition due to the volatilization of the ink moisture. It fluctuates to. By changing the balance between hydrophilicity and hydrophobicity in this way, the dispersion stability of the pigment contained in the ink is impaired, and there arises a problem that ejection disorder is likely to occur when continuous printing is performed.
However, according to the present invention, it is possible to provide an ink having excellent storage stability and ejection stability and capable of forming a high-quality image with suppressed beading, and further, this effect is combined with a circulating ejection head. Even in the case of, it is fully exhibited. Further, when the circulation type discharge head is used, a high-quality image with less discharge disturbance can be obtained, and at the same time, maintenance ink can be reduced. Therefore, when the above ink and the circulation type head are combined, there are few image defects such as beading and discharge disturbance. High-quality images can be obtained with high productivity. The circulation type discharge head will be described later separately.
Further, as this recording device, not only a desktop type but also a wide recording device capable of printing on an A0 size recording medium, or, for example, continuous paper wound in a roll shape can be used as a recording medium. A continuous line printer is also included.

An example of the recording device will be described with reference to FIGS. 1 and 2. FIG. 1 is a perspective explanatory view of the device. FIG. 2 is a perspective explanatory 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 unit 420 is provided in the exterior 401 of the image forming apparatus 400. Each ink container 411 of the main tank 410 (410k, 410c, 410m, 410y) for each color of black (K), cyan (C), magenta (M), and yellow (Y) is packaged with, for example, an aluminum laminate film. It is formed of members. The ink container 411 is housed in, for example, a plastic container case 414. 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 behind the opening when the cover 401c of the main body of the apparatus is opened. A main tank 410 is detachably attached to the cartridge holder 404. As a result, each ink ejection port 413 of the main tank 410 and the ejection head 434 for each color communicate with each other via the supply tube 436 for each color, and ink can be ejected from the ejection head 434 to the recording medium.

<Recording device with circulating discharge head, recording method>
In a recording device having a circulation type ejection head, the ink ejection means has a nozzle for ejecting the ink, a plurality of individual liquid chambers communicating with the nozzle, an inflow flow path for flowing the ink into the individual liquid chamber, and the ink. An ink ejection head having an outflow flow path for causing the ink to flow out of the individual liquid chamber, and a negative pressure generating means for generating a negative pressure for causing the ink to flow out of the individual liquid chamber.
The recording method having a circulation type ejection head is a step in which the ink ejection process causes the ink to flow into the individual liquid chambers through the inflow flow path and then causes the ink to flow out from the individual liquid chambers through the outflow flow path due to the generation of negative pressure. including.
An example of the circulation type discharge head will be described below with reference to FIGS. 3 to 8. FIG. 3 is an external perspective explanatory view of the liquid discharge head, FIG. 4 is a cross-sectional explanatory view in a direction orthogonal to the nozzle arrangement direction of the head, and FIG. 5 is a cross-sectional explanatory view in a direction parallel to the nozzle arrangement direction of the head. 6 is a plan explanatory view of the nozzle plate of the head, FIG. 7 is a plan explanatory view of each member constituting the flow path member of the head, and FIG. 8 is a plan explanatory view of each member constituting the common liquid chamber member of the head. Is.

In this liquid discharge head, a nozzle plate 1, a flow path plate 2, and a diaphragm member 3 as a wall surface member are laminated and joined. A piezoelectric actuator 11 that displaces the diaphragm member 3, a common liquid chamber member 20, and a cover 29 are provided.
The nozzle plate 1 has a plurality of nozzles 4 for discharging a liquid.
The flow path plate 2 forms an individual liquid chamber 6 leading to the nozzle 4, a fluid resistance portion 7 communicating with the individual liquid chamber 6, and a liquid introduction portion 8 communicating with the fluid resistance portion 7. Further, the flow path plate 2 is formed by laminating and joining a plurality of plate-shaped members 41 to 45 from the nozzle plate 1 side, and laminating and joining these plate-shaped members 41 to 45 and the diaphragm member 3 to form a flow path. The member 40 is configured.
The diaphragm member 3 has a filter portion 9 as an opening through the liquid introduction portion 8 and the common liquid chamber 10 formed by the common liquid chamber member 20.
The inflow flow path may be a flow path connected to the individual liquid chamber 6 and may be a flow path "in front" of the individual liquid chamber inflow, and the liquid introduction unit 8 and the common liquid chamber 10 correspond to the inflow flow path. To do.
The diaphragm member 3 is a wall surface member that forms the wall surface of the individual liquid chamber 6 of the flow path plate 2. The diaphragm member 3 has a two-layer structure (not limited), and is formed of a first layer for forming a thin-walled portion from the flow path plate 2 side and a second layer for forming a thick-walled portion, and the first layer is an individual liquid. A deformable vibration region 30 is formed in a portion corresponding to the chamber 6.

Here, as shown in FIG. 6, a plurality of nozzles 4 are arranged in a staggered pattern on the nozzle plate 1.
As shown in FIG. 7A, the plate-shaped member 41 constituting the flow path plate 2 includes a through groove portion (meaning a groove-shaped through hole) 6a constituting the individual liquid chamber 6 and a fluid resistance portion 51. Through groove portions 51a and 52a forming the circulation flow path 52 are formed.
Similarly, as shown in FIG. 7B, the plate-shaped member 42 is formed with a through groove portion 6b constituting the individual liquid chamber 6 and a through groove portion 52b forming the circulation flow path 52.
Similarly, as shown in FIG. 7C, the plate-shaped member 43 is formed with a through groove portion 6c constituting the individual liquid chamber 6 and a through groove portion 53a having the nozzle arrangement direction forming the circulation flow path 53 as the longitudinal direction. Has been done.
Similarly, as shown in FIG. 7D, the plate-shaped member 44 has a through groove portion 6d forming the individual liquid chamber 6, a through groove portion 7a forming the fluid resistance portion 7, and a penetration groove portion 8 forming the liquid introduction portion 8. The groove portion 8a and the through groove portion 53b having the nozzle arrangement direction forming the circulation flow path 53 as the longitudinal direction are formed. Similarly, as shown in FIG. 7E, the plate-shaped member 45 has a through groove portion 6e forming the individual liquid chamber 6 and a through groove portion 8b (filter) having the nozzle arrangement direction forming the liquid introduction portion 8 as the longitudinal direction. (It becomes a liquid chamber on the downstream side), and a through groove portion 53c having a longitudinal direction of the nozzle arrangement forming the circulation flow path 53 is formed.

As shown in FIG. 7 (f), the diaphragm member 3 is formed with a vibration region 30, a filter portion 9, and a through groove portion 53d whose longitudinal direction is the nozzle arrangement direction constituting the circulation flow path 53. ..
In this way, by forming the flow path member by laminating and joining a plurality of plate-shaped members, it is possible to form a complicated flow path with a simple structure.
With the above configuration, the flow path member 40 composed of the flow path plate 2 and the diaphragm member 3 has a fluid resistance portion 51, a circulation flow path 52, and circulation along the surface direction of the flow path plate 2 leading to each individual liquid chamber 6. A circulation flow path 53 in the thickness direction of the flow path member 40 leading to the flow path 52 is formed. The circulation flow path 53 is connected to the circulation common liquid chamber 50, which will be described later.
The outflow flow path may be a flow path connected to the individual liquid chamber 6 and may be a flow path "after" the inflow of the individual liquid chambers, and the circulation flow paths 52 and 53 and the common circulation liquid chamber 50 flow out. Corresponds to the road.

On the other hand, the common liquid chamber member 20 is formed with a common liquid chamber 10 to which liquid is supplied from the supply / circulation mechanism 494 and a circulation common liquid chamber 50.
As shown in FIG. 8A, the first common liquid chamber member 21 constituting the common liquid chamber member 20 has a through hole 25a for a piezoelectric actuator, a through groove portion 10a serving as a downstream common liquid chamber 10A, and circulation. A groove portion 50a having a bottom that serves as a common liquid chamber 50 is formed.
Similarly, as shown in FIG. 8B, the second common liquid chamber member 22 is formed with a through hole 25b for the piezoelectric actuator and a groove portion 10b serving as the upstream common liquid chamber 10B.
Further, with reference to FIG. 3, the second common liquid chamber member 22 is formed with a through hole 71a which is an end portion of the common liquid chamber 10 in the nozzle arrangement direction and a supply port portion through which the supply port 71 is passed.
Similarly, the first common liquid chamber member 21 and the second common liquid chamber member 22 are provided with the other end (the end opposite to the through hole 71a) of the circulation common liquid chamber 50 in the nozzle arrangement direction and the circulation port 81. Through holes 81a and 81b are formed.
In addition, in FIG. 8, the groove portion having a bottom is shown by applying a surface coating (the same applies to the following figures).
As described above, the common liquid chamber member 20 is composed of the first common liquid chamber member 21 and the second common liquid chamber member 22, and the first common liquid chamber member 21 is joined to the diaphragm member 3 side of the flow path member 40. Then, the second common liquid chamber member 22 is laminated and joined to the first common liquid chamber member 21.

Here, the first common liquid chamber member 21 forms a downstream common liquid chamber 10A which is a part of the common liquid chamber 10 leading to the liquid introduction portion 8 and a circulation common liquid chamber 50 leading to the circulation flow path 53. ing. Further, the second common liquid chamber member 22 forms the upstream common liquid chamber 10B which is the rest of the common liquid chamber 10.
At this time, the downstream common liquid chamber 10A and the circulation common liquid chamber 50, which are a part of the common liquid chamber 10, are arranged side by side in the direction orthogonal to the nozzle arrangement direction, and the circulation common liquid chamber 50 is the common liquid chamber 10. It is placed at the position projected inside.
As a result, the dimensions of the circulation common liquid chamber 50 are not restricted by the dimensions required for the flow path including the individual liquid chamber 6, the fluid resistance portion 7, and the liquid introduction portion 8 formed by the flow path member 40.
Then, the circulation common liquid chamber 50 and a part of the common liquid chamber 10 are arranged side by side, and the circulation common liquid chamber 50 is arranged at a position projected in the common liquid chamber 10 so as to be orthogonal to the nozzle arrangement direction. The width of the head in the direction can be suppressed, and the increase in size of the head can be suppressed. The common liquid chamber member 20 forms a circulation common liquid chamber 50 with a common liquid chamber 10 to which liquid is supplied from a head tank or a liquid cartridge.

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

The piezoelectric member 12 is formed by alternately stacking piezoelectric layers and internal electrodes. The internal electrodes are drawn out to their end faces to provide external electrodes, and the flexible wiring member 15 is connected to the external electrodes.
In the circulation type discharge head configured in this way, for example, by lowering the voltage applied to the piezoelectric element 12A from the reference potential, the piezoelectric element 12A contracts, the vibration region 30 of the diaphragm member 3 descends, and the individual liquid chamber 6 As the volume expands, the liquid flows into the individual liquid chamber 6.
After that, the voltage applied to the piezoelectric element 12A is increased to extend the piezoelectric element 12A in the stacking direction, and the vibration region 30 of the vibrating plate member 3 is deformed in the direction toward the nozzle 4 to contract the volume of the individual liquid chamber 6. As a result, the liquid in the individual liquid chamber 6 is pressurized, and the liquid is discharged from the nozzle 4.
Then, by returning the voltage applied to the piezoelectric element 12A to the reference potential, the vibration region 30 of the diaphragm member 3 is restored to the initial position, the individual liquid chamber 6 expands, and a negative pressure is generated. Therefore, at this time, the common liquid is generated. The liquid is filled from the chamber 10 into the individual liquid chamber 6. Therefore, after the vibration of the meniscus surface of the nozzle 4 is attenuated and stabilized, the operation for the next ejection is started.

The driving method of this head is not limited to the above example (pull-pushing), and pulling or pushing may be performed depending on the driving waveform. Further, in the above-described embodiment, the laminated piezoelectric element has been described as the pressure generating means for giving the pressure fluctuation to the individual liquid chamber 6, but the present invention is not limited to this, and a thin-film piezoelectric element can also be used. .. Further, it is possible to use a heat-generating resistor arranged in the individual liquid chamber 6 to generate air bubbles by the heat generated by the heat-generating resistor to cause pressure fluctuation, or to generate pressure fluctuation by using electrostatic force. ..

Next, an example of a liquid circulation system using a circulation type discharge head will be described with reference to FIG.
FIG. 9 is a block diagram showing a liquid circulation system.
As shown in FIG. 9, the liquid circulation system includes a main tank, a liquid discharge head, a supply tank, a circulation tank, a compressor, a vacuum pump, a first liquid feed pump, a second liquid feed pump, a regulator (R), and a supply side pressure. It consists of a sensor and a pressure sensor on the circulation side. The vacuum pump corresponds to a means for generating a negative pressure. The supply-side pressure sensor is connected between the supply tank and the liquid discharge head and is connected to the supply flow path side connected to the supply port 71 (see FIG. 3) of the liquid discharge head. The circulation side pressure sensor is connected between the liquid discharge head and the circulation tank and is connected to the circulation flow path side connected to the circulation port 81 (see FIG. 3) of the liquid discharge head.

One of the circulation tanks is connected to the supply tank via the first liquid feed pump, and the other of the circulation tanks is connected to the main tank via the second liquid feed pump. As a result, the liquid flows from the supply tank through the supply port 71 into the liquid discharge head, is discharged from the circulation port and is discharged to the circulation tank, and further, the liquid is sent from the circulation tank to the supply tank by the first liquid feed pump. The liquid circulates by being pumped.
Further, a compressor is connected to the supply tank, and the pressure sensor on the supply side is controlled so that a predetermined positive pressure is detected. On the other hand, a vacuum pump is connected to the circulation tank, and the circulation side pressure sensor is controlled so that a predetermined negative pressure is detected. As a result, the negative pressure of the meniscus can be kept constant while circulating the liquid through the liquid discharge head.
Further, when droplets are discharged from the nozzle of the circulation type discharge head, the amount of liquid in the supply tank and the circulation tank decreases. Therefore, the second liquid feed pump is appropriately used from the main tank to the circulation tank. It is desirable to replenish the liquid. The timing of liquid refilling from the main tank to the circulation tank depends on the detection result of the liquid level sensor provided in the circulation tank, such as refilling the liquid when the liquid level height of the ink in the circulation tank falls below the specified height. Can be controlled.

Next, the circulation of the liquid in the circulation type discharge head will be described. As shown in FIG. 3, a supply port 71 communicating with the common liquid chamber and a circulation port 81 communicating with the circulation common liquid chamber 50 are formed at the end of the common liquid chamber member 20. The supply port 71 and the circulation port 81 are each connected to a supply tank / circulation tank (see FIG. 9) for storing liquid via a tube. Then, the liquid stored in the supply tank is supplied to the individual liquid chamber 6 via the supply port 71, the common liquid chamber 10, the liquid introduction section 8, and the fluid resistance section 7.
Further, while the liquid in the individual liquid chamber 6 is discharged from the nozzle 4 by the drive of the piezoelectric element 12, some or all of the liquid that remains in the individual liquid chamber 6 without being discharged is circulated in the fluid resistance portion 51. It is circulated to the circulation tank through the flow paths 52 and 53, the circulation common liquid chamber 50, and the circulation port 81.

It should be noted that the circulation of the liquid can be carried out not only when the circulation type discharge head is operated but also when the operation is stopped. By circulating during the suspension of operation, the liquid in the individual liquid chamber is constantly refreshed, and the aggregation and sedimentation of the components contained in the liquid can be suppressed, which is preferable. On the other hand, a vacuum pump is connected to the circulation tank to keep the negative pressure of the meniscus constant, but if a highly volatile component is contained in the liquid, this gradually volatilizes and the composition of the liquid changes. There is also the problem that it fluctuates over time. In particular, when a water-based pigment ink containing water is used, the water contained in the ink volatilizes, so that the ink changes to a hydrophobic composition. By changing the balance between hydrophilicity and hydrophobicity in this way, the dispersion stability of the pigment contained in the ink is impaired, and there arises a problem that ejection disturbance is likely to occur when continuous printing is performed. High-quality images with few image defects such as ejection turbulence can be obtained even when a circulating head is used in combination with the ink of the present invention, which can maintain good dispersion stability even in a highly hydrophobic composition. You can get it with productivity.

Next, an example of a device that discharges a liquid using a circulation type discharge head will be described with reference to FIGS. 10 and 11. FIG. 10 is a plan view of the main part of the device, and FIG. 11 is a side view of the main part of the device.
This device is a serial type device, and the carriage 403 is reciprocated in the main scanning direction by the main scanning moving mechanism 493. The main scanning movement mechanism 493 includes a guide member 401, a main scanning motor 405, a timing belt 408, and the like. The guide member 401 is bridged over the left and right side plates 491A and 491B to movably hold the carriage 403. Then, the carriage 403 is reciprocated in the main scanning direction by the main scanning motor 405 via the timing belt 408 bridged between the drive pulley 406 and the driven pulley 407.
The carriage 403 is equipped with a liquid discharge unit 440 equipped with a liquid discharge head 404. The liquid discharge head 404 of the liquid discharge unit 440 discharges liquids of, for example, yellow (Y), cyan (C), magenta (M), and black (K). Further, the liquid discharge head 404 is mounted by arranging a nozzle array composed of a plurality of nozzles in the sub-scanning direction orthogonal to the main scanning direction and directing the discharge direction downward.

The liquid is supplied and circulated in the liquid discharge head 404 by the supply / circulation mechanism 494 for supplying the liquid stored outside the liquid discharge head 404 to the liquid discharge head 404. In this example, the supply / circulation mechanism 494 includes a supply tank, a circulation tank, a compressor, a vacuum pump, a liquid feed pump, a regulator (R), and the like. Further, the supply side pressure sensor is connected between the supply tank and the liquid discharge head and on the supply flow path side connected to the supply port 71 of the liquid discharge head. The circulation side pressure sensor is connected between the liquid discharge head and the circulation tank and is connected to the circulation flow path side connected to the circulation port 81 of the liquid discharge head.

This device includes a transport mechanism 495 for transporting the paper 410. The transport mechanism 495 includes a transport belt 412, which is a transport means, and a sub-scanning motor 416 for driving the transport belt 412.
The transport belt 412 attracts the paper 410 and transports it to a position facing the liquid discharge head 404. The transport belt 412 is an endless belt, and is hung between the transport roller 413 and the tension roller 414. Adsorption can be performed by electrostatic adsorption, air suction, or the like.
Then, the transport belt 412 orbits in the sub-scanning direction by rotationally driving the transport roller 413 via the timing belt 417 and the timing pulley 418 by the sub-scanning motor 416.

Further, on one side of the carriage 403 in the main scanning direction, a maintenance / recovery mechanism 420 for maintaining / recovering the liquid discharge head 404 is arranged on the side of the transport belt 412.
The maintenance / recovery mechanism 420 is composed of, for example, a cap member 421 that caps the nozzle surface (the surface on which the nozzle is formed) of the liquid discharge head 404, a wiper member 422 that wipes the nozzle surface, and the like.
The main scanning movement mechanism 493, the supply / circulation mechanism 494, the maintenance / recovery mechanism 420, and the transport mechanism 495 are attached to a housing including the side plates 491A and 491B and the back plate 491C.
In this device configured in this way, the paper 410 is fed onto the transport belt 412 and sucked, and the paper 410 is transported in the sub-scanning direction by the orbital movement of the transport belt 412.

Therefore, by driving the liquid discharge head 404 in response to the image signal while moving the carriage 403 in the main scanning direction, the liquid is discharged to the stopped paper 410 to form an image.
As described above, since this device includes the circulation type discharge head, a high-quality image can be stably formed.

Next, another example of the liquid discharge unit will be described with reference to FIG. FIG. 12 is an explanatory plan view of a main part of the unit.
This liquid discharge unit includes a housing portion composed of side plates 491A, 491B and a back plate 491C, a main scanning movement mechanism 493, a carriage 403, and a liquid among the members constituting the device for discharging the liquid. It is composed of a discharge head 404.
It is also possible to form a liquid discharge unit in which at least one of the above-mentioned maintenance / recovery mechanism 420 and the supply / circulation mechanism 494 is further attached to, for example, the side plate 491B of the liquid discharge unit.
In the present application, the "liquid discharge head" is a functional component that discharges and ejects a liquid from a nozzle.

Piezoelectric actuators (laminated piezoelectric elements and thin-film piezoelectric elements), thermal actuators that use electrothermal conversion elements such as heat-generating resistors, and electrostatic actuators that consist of a vibrating plate and counter electrodes are used as energy sources for discharging liquid. Includes what to do.

This recording device can include not only a portion that ejects ink, but also a device called a pretreatment device, a posttreatment device, and the like.
As one aspect of the pretreatment apparatus and the posttreatment apparatus, the pretreatment liquid and the posttreatment liquid are provided as in the case of inks such as black (K), cyan (C), magenta (M), and yellow (Y). There is an embodiment in which a liquid accommodating portion and a liquid discharge head are added, and a pretreatment liquid or a posttreatment liquid is discharged by an inkjet recording method.
As another aspect of the pretreatment device and the posttreatment device, there is a mode in which a pretreatment device and a posttreatment device by, for example, a blade coating method, a roll coating method, and a spray coating method are provided other than the inkjet recording method.

The method of using the ink is not limited to the inkjet recording method, and can be widely used. In addition to the inkjet recording method, examples thereof include a blade coating method, a gravure coating method, a bar coating method, a roll coating method, a dip coating method, a curtain coating method, a slide coating method, a die coating method, and a spray coating method.

The use of the ink of the present invention is not particularly limited and may be appropriately selected depending on the intended purpose. For example, it can be applied to printed matter, paints, coating materials, base materials and the like. Further, it can be used not only as an ink to form two-dimensional characters and images, but also as a material for three-dimensional modeling for forming a three-dimensional three-dimensional image (three-dimensional model).
As a three-dimensional modeling device for modeling a three-dimensional object, a known one can be used, and the device is not particularly limited, but for example, an device provided with ink accommodating means, supply means, ejection means, drying means and the like is used. be able to. The three-dimensional model includes a three-dimensional model obtained by overcoating with ink. In addition, a molded product obtained by processing a structure in which ink is applied on a base material such as a recording medium is also included. The molded product is, for example, a recorded material or structure formed in the form of a sheet or a film, which has been subjected to molding processing such as heat stretching or punching. For example, an automobile, an OA device, or electricity. -Suitably used for molding after decorating the surface of electronic devices, meters of cameras, panels of operation parts, etc.

The present invention relates to the following method for producing ink (1), but also includes the following (2) to (5) as embodiments.
(1) C.I. I. Pigment Red 122, C.I. I. Pigment Red 202, C.I. I. Pigment Red 209, and C.I. I. One or more pigments selected from Pigment Violet 19, quinacridone pigment, synergist with quinacridone skeleton, dispersant with polyoxyethylene structure and solubility parameter of 9.00 (cal / cm ³ ) ^1/2 or more 11.80 (Cal / cm ³ ) A method for producing an ink, which comprises a step of heat-treating a mixture containing an organic solvent of ^1/2 or less using a heater.
The content of the organic solvent with respect to the total amount of the ink is 30% by mass or more and 60% by mass or less.
A method for producing an ink in which the viscosity change rate before and after the sealing heating and the particle size change rate before and after heating are both −5% or more and 1% or less when the ink is sealed and heated at 80 ° C. for 4 weeks.
(2) One or more organic solvents in which the organic solvent is selected from 3-butoxy-N, N-dimethylpropanamide, N, N-dimethyl-3-propaneamide and 3-ethoxy-N, N-dimethylpropanamide. The method for producing an ink according to (1) above.
(3) The method for producing an ink according to (1) or (2) above, wherein the synergist is a sulfonic acid derivative of quinacridone.
(4) The method for producing an ink according to any one of (1) to (3) above, wherein the heat treatment is performed at 30 ° C. or higher in the heat treatment step.
(5) The method for producing an ink according to any one of (1) to (3) above, wherein the heat treatment is performed at 30 ° C. or higher and 80 ° C. or lower in the heat treatment step.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited to the following Examples.
Further, in the following description, unless otherwise specified, "parts" indicates "parts by mass" and "%" indicates "% by mass".

(Example 1)
<Preparation of pigment dispersion>
An aqueous solution of 10% by mass of a polymer dispersant having a polyoxyethylene structure (BYKJET-9151, manufactured by Big Chemie) was prepared. Add 100 g of this aqueous solution, 50 g of a quinacridone pigment (manufactured by DIC, FASTOGEN Super Magenta JM2120, CI Pigment Red 202 / Pigment Violet 19 mixed crystal) containing a sulfonic acid derivative synergist of quinacridone, and 150 g of ion-exchanged water for 12 hours. Stirred. The obtained mixture was circulated and dispersed at a peripheral speed of 10 m / s for 1 hour using a disk-type bead mill (manufactured by Simmal Enterprises, KDL type, media: using zirconia balls having a diameter of 0.1 mm), and then the pore diameter was 1. The mixture was filtered through a 2 μm membrane filter, and an adjusted amount of ion-exchanged water was added to obtain a pigment dispersion (solid content concentration: 15% by mass).

<Making ink>
30 g of the above pigment dispersion, 30 g of 3-butoxy-N, N-dimethylpropanamide (solubility parameter: 9.03), Zonyl FS-300 (DuPont, fluorine-based surfactant, solid content concentration 40% by mass) 1 g and 39 g of ion-exchanged water were mixed, stirred for 1 hour, and then heat-treated at 80 ° C. for 6 hours in a sealed state. Further, the ink of Example 1 was obtained by filtering with a membrane filter having a pore size of 0.8 μm.

(Example 2)
<Preparation of pigment dispersion>
An aqueous solution of 10% by mass of a polymer dispersant having a polyoxyethylene structure (BYKJET-9152, manufactured by Big Chemie) was prepared. Add 100 g of this aqueous solution, 50 g of a quinacridone pigment containing a sulfonic acid derivative synergist of quinacridone (FASTOGEN Super Magenta RFS, CI Pigment Red 122 / Pigment Violet 19 mixed crystal, manufactured by DIC Corporation) and 150 g of ion-exchanged water for 12 hours. Stirred. The obtained mixture was circulated and dispersed at a peripheral speed of 10 m / s for 1 hour using a disk-type bead mill (manufactured by Simmal Enterprises, KDL type, media: using zirconia balls having a diameter of 0.1 mm), and then the pore diameter was 1. The mixture was filtered through a 2 μm membrane filter, and an adjusted amount of ion-exchanged water was added to obtain a pigment dispersion (solid content concentration: 15% by mass).

<Making ink>
30 g of the above pigment dispersion, 40 g of N, N-dimethyl-3-propaneamide (solubility parameter: 9.08), 1 g of Zonyl FS-300 (DuPont, fluorine-based surfactant, solid content concentration 40% by mass) , And 29 g of ion-exchanged water were mixed and stirred for 1 hour, and then heat-treated at 70 ° C. for 12 hours in a sealed state. Further, the ink of Example 2 was obtained by filtering with a membrane filter having a pore size of 0.8 μm.

(Example 3)
<Synergist synthesis>
40 g of 98% sulfuric acid was placed in a 100 mL four-necked flask, and 5 g of 2,9-dimethylquinacridone was added little by little. Next, the reaction was carried out by setting the temperature to 90 ° C. and stirring for 5 hours, and then the temperature was returned to room temperature. The reaction solution was added little by little while stirring 400 g of ice water to obtain a reddish purple precipitate. This was filtered off with a glass filter, washed three times with 200 g of ion-exchanged water, and then dried under reduced pressure by heating at 60 ° C. to obtain 2.3 g of a sulfonic acid derivative of 2,9-dimethylquinacridone.

<Synthesis of polymer dispersant>
A monomer solution was prepared by dissolving 10 g of acrylic acid, 20 g of Blemmer PME-1000 (reactive monomer having a polyoxyethylene structure manufactured by Nichiyu Co., Ltd.), 5 g of benzyl methacrylate and 5 g of butyl methacrylate in 150 mL of dry methyl ethyl ketone. After heating 10% of the monomer solution to 75 ° C. under an argon stream, a solution prepared by dissolving 0.62 g of 2,2'-azoiso (butyronitrile) in the remaining monomer solution was added dropwise over 1.5 hours to 75. The mixture was stirred at ° C. for 6 hours. The mixture was cooled to room temperature, and the obtained reaction solution was dropped onto hexane. The supernatant was discarded to obtain a precipitated copolymer. The obtained copolymer was dissolved in tetrahydrofuran, evaporated, and dried under reduced pressure to obtain 39.2 g of polymer dispersant A (weight average molecular weight Mw: 16500, number average molecular weight Mn: 7200). It was.

<Preparation of pigment dispersion>
A 10% aqueous solution of the polymer dispersant A having the polyoxyethylene structure was prepared. 100 g of this aqueous solution, 47 g of a quinacridone pigment (FASTOGEN Super Magenta RTS, CI Pigment Red 122, manufactured by DIC Corporation), 3 g of a sulfonic acid derivative of 2,9-dimethylquinacridone, and 150 g of ion-exchanged water were added and stirred for 12 hours. The obtained mixture was circulated and dispersed at a peripheral speed of 10 m / s for 1 hour using a disk-type bead mill (manufactured by Simmal Enterprises, KDL type, media: using zirconia balls having a diameter of 0.1 mm), and then the pore diameter was 1. The mixture was filtered through a 2 μm membrane filter, and an adjusted amount of ion-exchanged water was added to obtain a pigment dispersion (solid content concentration: 15% by mass).

<Making ink>
30 g of the above pigment dispersion, 50 g of 3-ethoxy-N, N-dimethylpropanamide (solubility parameter: 9.13), Zonyl FS-300 (DuPont, fluorine-based surfactant, solid content concentration 40% by mass) After mixing 1 g and 19 g of ion-exchanged water and stirring for 1 hour, heat treatment was performed at 60 ° C. for 24 hours in a sealed state. Further, the ink of Example 3 was obtained by filtering with a membrane filter having a pore size of 0.8 μm.

(Example 4)
<Synergist synthesis>
40 g of 98% sulfuric acid was placed in a 100 mL four-necked flask, and 5 g of 3,10-dichloroquinacridone was added little by little. Next, the reaction was carried out by setting the temperature to 90 ° C. and stirring for 5 hours, and then the temperature was returned to room temperature. The reaction solution was added little by little while stirring 400 g of ice water to obtain a reddish purple precipitate. This was filtered off with a glass filter, washed three times with 200 g of ion-exchanged water, and then dried under reduced pressure by heating at 60 ° C. to obtain 2.2 g of a sulfonic acid derivative of 3,10-dichloroquinacridone.

<Preparation of pigment dispersion>
A 10% aqueous solution of a polymer dispersant (Dispex Ultra PA 4550, manufactured by BASF) was prepared. Add 100 g of this aqueous solution, 47 g of a quinacridone pigment (FASTOGEN Super Magenta Red 209228-6736, CI Pigment Red 209) manufactured by DIC, 3 g of a sulfonic acid derivative of 3,10-dichloroquinacridone, and 150 g of ion-exchanged water for 12 hours. Stirred. The obtained mixture was circulated and dispersed at a peripheral speed of 10 m / s for 1 hour using a disk-type bead mill (manufactured by Simmal Enterprises, KDL type, media: using zirconia balls having a diameter of 0.1 mm), and then the pore diameter was 1. The mixture was filtered through a 2 μm membrane filter, and an adjusted amount of ion-exchanged water was added to obtain a pigment dispersion (solid content concentration: 15% by mass).

<Making ink>
30 g of the above pigment dispersion, 60 g of 3-methoxy-N, N-dimethylpropanamide (solubility parameter: 9.19), Zonyl FS-300 (DuPont, fluorine-based surfactant, solid content concentration 40% by mass) 1 g and 9 g of ion-exchanged water were mixed, stirred for 1 hour, and then heat-treated at 50 ° C. for 48 hours in a sealed state. Further, the ink of Example 4 was obtained by filtering with a membrane filter having a pore size of 0.8 μm.

(Example 5)
<Synergist synthesis>
40 g of 98% sulfuric acid was placed in a 100 mL four-necked flask, and 5 g of 2,9-dichloroquinacridone was added little by little. Next, the reaction was carried out by setting the temperature to 90 ° C. and stirring for 5 hours, and then the temperature was returned to room temperature. The reaction solution was added little by little while stirring 400 g of ice water to obtain a reddish purple precipitate. This was filtered off with a glass filter, washed three times with 200 g of ion-exchanged water, and then dried under reduced pressure by heating at 60 ° C. to obtain 2.1 g of a sulfonic acid derivative of 2,9-dichloroquinacridone.

<Preparation of pigment dispersion>
A 10% aqueous solution of a polymer dispersant (Dispex Ultra PA 4560, manufactured by BASF) was prepared. 100 g of this aqueous solution, 47 g of a quinacridone pigment (BASF, Cinquasia Magenta D 4500 J, CI Pigment Red 202 / Pigment Violet 19 mixed crystal), 3 g of a sulfonic acid derivative of 2,9-dichloroquinacridone, and 150 g of ion-exchanged water. In addition, it was stirred for 12 hours. The obtained mixture was circulated and dispersed at a peripheral speed of 10 m / s for 1 hour using a disk-type bead mill (manufactured by Simmal Enterprises, KDL type, media: using zirconia balls having a diameter of 0.1 mm), and then the pore diameter was 1. The mixture was filtered through a 2 μm membrane filter, and an adjusted amount of ion-exchanged water was added to obtain a pigment dispersion (solid content concentration: 15% by mass).

<Making ink>
30 g of the above pigment dispersion, 40 g of 3-ethyl-3-oxetanemethanol (solubility parameter: 11.31), 1 g of Zonyl FS-300 (DuPont, fluorine-based surfactant, solid content concentration 40% by mass), and 29 g of ion-exchanged water was mixed, stirred for 1 hour, and then heat-treated at 40 ° C. for 72 hours in a sealed state. Further, the ink of Example 5 was obtained by filtering with a membrane filter having a pore size of 0.8 μm.

(Example 6)
<Synergist synthesis>
40 g of 98% sulfuric acid was placed in a 100 mL four-necked flask, and 5 g of unsubstituted quinacridone was added little by little. Next, the reaction was carried out by setting the temperature to 90 ° C. and stirring for 5 hours, and then the temperature was returned to room temperature. The reaction solution was added little by little while stirring 400 g of ice water to obtain a reddish purple precipitate. This was filtered off with a glass filter, washed three times with 200 g of ion-exchanged water, and then dried under reduced pressure by heating at 60 ° C. to obtain 2.0 g of a sulfonic acid derivative of unsubstituted quinacridone.

<Preparation of pigment dispersion>
A 10% aqueous solution of a polymer dispersant (PX 4585, manufactured by BASF) was prepared. Add 100 g of this aqueous solution, 47 g of a quinacridone pigment (Ink Jet Magenta E7B VP 3985, CI Pigment Red 122 / Pigment Violet 19 mixed crystal) manufactured by Clariant, 3 g of a sulfonic acid derivative of unsubstituted quinacridone, and 150 g of ion-exchanged water. The mixture was stirred for 12 hours. The obtained mixture was circulated and dispersed at a peripheral speed of 10 m / s for 1 hour using a disk-type bead mill (manufactured by Simmal Enterprises, KDL type, media: using zirconia balls having a diameter of 0.1 mm), and then the pore diameter was 1. The mixture was filtered through a 2 μm membrane filter, and an adjusted amount of ion-exchanged water was added to obtain a pigment dispersion (solid content concentration: 15% by mass).

<Making ink>
30 g of the above pigment dispersion, 40 g of 3-methyl-3-oxetanemethanol (solubility parameter: 11.79), 1 g of Zonyl FS-300 (DuPont, fluorine-based surfactant, solid content concentration 40% by mass), and 29 g of ion-exchanged water was mixed, stirred for 1 hour, and then heat-treated at 30 ° C. for 120 hours in a sealed state. Further, the ink of Example 6 was obtained by filtering with a membrane filter having a pore size of 0.8 μm.

(Example 7)
The ink of Example 7 was obtained in the same manner as in Example 5 except that 40 g of 3-ethyl-3-oxetanemethanol (solubility parameter: 11.31) used for preparing the ink of Example 5 was changed as follows. ..
3-Ethyl-3-oxetane methanol (solubility parameter: 11.31) 30 g
1,2-pentanediol (solubility parameter: 12.21) 10 g

(Example 8)
The ink of Example 8 was obtained in the same manner as in Example 5 except that 40 g of 3-ethyl-3-oxetanemethanol (solubility parameter: 11.31) used for preparing the ink of Example 5 was changed as follows. ..
3-Ethyl-3-oxetanemethanol (solubility parameter: 11.31) 10 g
1,2-Hexanediol (solubility parameter: 11.80) 30 g

(Example 9)
The ink of Example 9 was obtained in the same manner as in Example 5 except that 40 g of 3-ethyl-3-oxetanemethanol (solubility parameter: 11.31) used for preparing the ink of Example 5 was changed as follows. ..
3-Ethyl-3-oxetane methanol (solubility parameter: 11.31) 35 g
1,7-Heptane diol (solubility parameter: 11.61) 5 g

(Comparative Example 1)
The ink of Comparative Example 1 was prepared in the same manner as in Example 1 except that the preparation of the ink of Example 1 was changed as follows.
<Making ink>
Pigment dispersion prepared in Example 1, 3-butoxy-N, N-dimethylpropanamide (solubility parameter: 9.03) 25 g, Zonyl FS-300 (DuPont, fluorine-based surfactant, solid content concentration) 1 g of 40% by mass) and 44 g of ion-exchanged water were mixed, stirred for 1 hour, and then heat-treated at 80 ° C. for 6 hours in a sealed state. Further, the ink of Comparative Example 1 was obtained by filtering with a membrane filter having a pore size of 0.8 μm.

(Comparative Example 2)
The ink of Comparative Example 2 was prepared in the same manner as in Example 4 except that the preparation of the ink of Example 4 was changed as follows.
<Making ink>
Pigment dispersion prepared in Example 4, 3-methoxy-N, N-dimethylpropanamide (solubility parameter: 9.19) 65 g, Zonyl FS-300 (DuPont, fluorine-based surfactant, solid content concentration) 1 g of 40% by mass) and 4 g of ion-exchanged water were mixed, stirred for 1 hour, and then heat-treated at 50 ° C. for 48 hours in a sealed state. Further, the ink of Comparative Example 2 was obtained by filtering with a membrane filter having a pore size of 0.8 μm.

(Comparative Example 3)
The ink of Comparative Example 3 was prepared in the same manner as in Example 3 except that the pigment dispersion of Example 3 was changed as follows.
<Preparation of pigment dispersion>
A 10% aqueous solution of a polymer dispersant (BYKJET-9170, manufactured by Big Chemie) was prepared. 100 g of this aqueous solution, 50 g of a quinacridone pigment (FASTOGEN Super Magenta RTS, CI Pigment Red 122 manufactured by DIC Corporation) and 150 g of ion-exchanged water were added and stirred for 12 hours. The obtained mixture was circulated and dispersed at a peripheral speed of 10 m / s for 1 hour using a disk-type bead mill (manufactured by Simmal Enterprises, KDL type, media: using zirconia balls having a diameter of 0.1 mm), and then the pore diameter was 1. The mixture was filtered through a 2 μm membrane filter, and an adjusted amount of ion-exchanged water was added to obtain a pigment dispersion (solid content concentration: 15% by mass).

(Comparative Example 4)
The ink of Comparative Example 4 was prepared in the same manner as in Example 3 except that the polymer dispersant used in Example 3 was changed to the one synthesized as follows.
<Synthesis of polymer dispersant>
A monomer solution was prepared by dissolving 10 g of acrylic acid, 10 g of styrene, 10 g of benzyl methacrylate and 10 g of butyl methacrylate in 150 mL of dry methyl ethyl ketone. After heating 10% of the monomer solution to 75 ° C. under an argon stream, a solution of 0.82 g of 2,2'-azoiso (butyronitrile) dissolved in the remaining monomer solution was added dropwise over 1.5 hours to 75. The mixture was stirred at ° C. for 6 hours. The mixture was cooled to room temperature, and the obtained reaction solution was dropped onto hexane. The supernatant was discarded to obtain a precipitated copolymer. The obtained copolymer was dissolved in tetrahydrofuran, evaporated, and dried under reduced pressure to obtain 38.8 g of polymer dispersant B (weight average molecular weight Mw: 15000, number average molecular weight Mn: 6300). It was.

(Comparative Example 5)
The ink of Comparative Example 5 was produced in the same manner as in Example 3 except that the ink used in Example 3 was not heat-treated.

(Comparative Example 6)
The ink of Comparative Example 6 was prepared in the same manner as in Example 1 except that the preparation of the ink of Example 1 was changed as follows.
<Making ink>
Pigment dispersion prepared in Example 1, 3-hexyloxy-N, N-dimethylpropanamide (solubility parameter: 8.96) 25 g, Zonyl FS-300 (DuPont, fluorine-based surfactant, solid content) 1 g of concentration 40% by mass) and 44 g of ion-exchanged water were mixed, stirred for 1 hour, and then heat-treated at 80 ° C. for 6 hours in a sealed state. Further, the ink of Comparative Example 6 was obtained by filtering with a membrane filter having a pore size of 0.8 μm.

(Comparative Example 7)
The ink of Comparative Example 7 was prepared in the same manner as in Example 1 except that the preparation of the ink of Example 1 was changed as follows.
<Making ink>
30 g of the pigment dispersion prepared in Example 1, 25 g of cyclopentanol (solubility parameter: 11.87), 1 g of Zonyl FS-300 (DuPont, fluorine-based surfactant, solid content concentration 40% by mass), and ions. After 44 g of exchanged water was mixed and stirred for 1 hour, heat treatment was performed at 80 ° C. for 6 hours in a sealed state. Further, the ink of Comparative Example 7 was obtained by filtering with a membrane filter having a pore size of 0.8 μm.

Tables 1 to 3 show the components of the inks of Examples 1 to 9 and Comparative Examples 1 to 7 and the blending ratios of the pigment dispersion, the organic solvent, the surfactant and the ion-exchanged water in the ink.
In addition, storage stability, ejection stability, and beading were evaluated using the inks of Examples 1 to 9 and Comparative Examples 1 to 7.
For storage stability, the viscosity change rate, the D50 change rate, and the D90 change rate were evaluated.
The evaluation method is shown below. The evaluation results are shown in Table 4.

(Evaluation methods)
<Storage stability>
After preparing the inks of Examples and Comparative Examples, 20 g of ink was weighed into a glass container (Laboran screw tube bottle No. 6 30 mL manufactured by AS ONE), the lid was closed, and the boundary between the glass container and the lid was covered with PTFE sealing tape. It was sealed with (As One Fluorine Sealing Tape) and allowed to stand at room temperature for 24 hours with the ink volatilization suppressed. The viscosity and particle size of this sample were measured under the conditions shown below to obtain the characteristic values of the inks of Examples and Comparative Examples before storage. Next, in the same manner as above, 20 g of ink was weighed into a glass container (As One Laboratory Screw Bottle No. 6 30 mL), the lid was closed, and the boundary between the glass container and the lid was sealed with PTFE sealing tape (As One Fluorine). It was sealed with (seal tape) and stored statically for 4 weeks in a small environmental tester (SU-221 manufactured by Espec Co., Ltd.) set at 80 ° C. in a state where ink volatilization was suppressed over time. After storage for 4 weeks, the sample is taken out from a small environmental tester, allowed to stand in a room temperature environment for 3 hours to return the sample temperature to room temperature, and then stored by opening the sealing tape and lid and measuring the viscosity and particle size. Later characteristic values were obtained. Using the characteristic values before and after storage, the rate of change of the characteristic values was calculated from the following formula. In addition, the amount of ink volatilized during storage was confirmed by measuring the sample mass before and after storage for 4 weeks, and it was confirmed that the ink mass reduction after storage was 0.05 g or less, and significant ink volatilization occurred. I confirmed that there was no such thing.

A viscometer (TVE-25L, manufactured by Toki Sangyo Co., Ltd.) was used to measure the viscosity, and the viscosity of a 1.1 ml sample was measured with a standard cone rotor (1 ° 34'x R24). The sample temperature was set to 25 ° C. using a circulating constant temperature bath. Further, the rotor rotation speed at the time of viscosity measurement was set so that the measured value was 50 to 90% of the measurement upper limit value. Other measurement conditions were as follows.

Measurement mode: Time auto stop measurement mode Measurement range: M
Unit of measurement: mPas
Measurement stop time: 120 seconds Preheat function: ON
Preheat time: 120 seconds

A particle size distribution measuring device (Nanotrac Wave manufactured by Nikkiso Co., Ltd.) was used for measuring the particle size, and the measurement conditions were set as follows. The inside of the cell was sufficiently washed with clean pure water obtained from a pure water device (Purelite PRO-0100 manufactured by Organo Corporation), and the clean pure water was put into the cell. After visually confirming that there were no bubbles in the cell and that there was no fluctuation or movement in the cell, set zero measurement was performed, and then the pure water in the cell was taken out. Next, prepare a sample solution obtained by diluting the ink with pure water so that the pigment concentration becomes 0.05%, wash the inside of the cell three times with this sample solution, and then put the sample solution into the cell. After visually confirming that there were no bubbles in the cell and that there was no fluctuation or movement in the cell, the particle size distribution was measured, and the 50% diameter and 90% diameter were measured.

Set zero time: 60 seconds Measurement time: 120 seconds Number of measurements: 1 time Transparency: Transmitted particle refractive index: 1.51
Shape: Non-spherical Density: 1.40
Solvent refractive index: 1.333
Viscosity at high temperature: 30 ° C 0.797
Viscosity at low temperature: 20 ° C 1.002
Filter: Stand: Norm
Sensitivity: Standard

<Discharge stability>
Each ink was set in an inkjet printer (IPSiO GX-e5500 manufactured by Ricoh) having a discharge head other than the circulation type discharge head, and 1000 print charts having a print area of 5% were printed. Immediately after printing 1000 sheets and after a 24-hour pause from the end of printing, 5 sheets each of solid images, halftone images, and nozzle check patterns are printed on industrial inkjet paper (Mitsubishi Paper Mills, SWORD iJET 4.3 gloss), and the images are printed. Disturbance of discharge and clogging of the nozzle were evaluated by visually observing the uniformity and the presence or absence of nozzle omission. The printing conditions were 100% duty and one-pass printing with a recording density of 600 × 300 dpi. The evaluation criteria are shown below.
[Evaluation criteria]
A: No discharge disturbance and no nozzle clogging B: Discharge is slightly disturbed but nozzle clogging C: Discharge is greatly disturbed and nozzle is also clogged

<Beading>
The degree of density unevenness was visually evaluated for the solid image printed with the above ejection stability. They were ranked according to the following evaluation criteria.
[Evaluation criteria]
A: No density unevenness B: Slight density unevenness C: Large density unevenness

<Discharge stability using a circulation type discharge head>
Each ink was set in an inkjet printer (manufactured by Ricoh, IPSiO GX-e5500 modified machine) equipped with the circulation type ejection head shown in FIGS. 3 to 11, and 1000 print charts having a print area of 5% were printed. Immediately after printing 1000 sheets and after a 48-hour pause from the end of printing, 5 sheets each of solid images, halftone images, and nozzle check patterns are printed on industrial inkjet paper (Mitsubishi Paper Mills, SWORD iJET 4.3 gloss), and the images are printed. Disturbance of discharge and clogging of the nozzle were evaluated by visually observing the uniformity and the presence or absence of nozzle omission. The printing conditions were 100% duty and one-pass printing with a recording density of 600 × 300 dpi. The evaluation criteria are shown below. During this evaluation, the ink was always circulated under negative pressure regardless of the operation / pause of the circulation type ejection head.
[Evaluation criteria]
A: No discharge disturbance and no nozzle clogging B: Discharge is slightly disturbed but nozzle clogging C: Discharge is slightly disturbed but nozzle clogging D: Discharge is greatly disturbed and nozzle is also clogged

It can be seen that the inks of the present invention of Examples 1 to 9 are superior to the inks of Comparative Examples 1 to 7 in terms of storage stability, ejection stability, and high-quality image formation. Further, it can be seen that the ink of the present invention has excellent ejection stability even in a recording device using a circulation type ejection head.
In Comparative Examples 3, 4 and 6, since the rate of change in storage stability was large, the discharge stability, beading, and discharge stability using the circulation type discharge head were not evaluated.

(About Fig. 1 and Fig. 2)
400 Image forming device 401 Image forming device exterior 401c Device body cover 404 Cartridge holder 410 Main tank 410k, 410c, 410m, 410y For each color of black (K), cyan (C), magenta (M), yellow (Y) Main tank 411 Ink storage unit 413 Ink discharge port 414 Storage container case 420 Mechanical unit 434 Discharge head 436 Supply tube

(About FIGS. 3 to 8)
1 Nozzle plate 2 Flow path plate 3 Vibrating plate member 4 Nozzle 6 Individual liquid chambers 6a, 6b, 6c, 6d, 6e Through groove part that constitutes the individual liquid chamber 7 Fluid resistance part 7a Through groove part that constitutes the fluid resistance part 8 Liquid introduction Part 8a, 8b Through groove part 9 Filter part 10 Common liquid chamber 10A Downstream side common liquid chamber 10a Through groove part 10B Upstream side common liquid chamber 10b Groove part 11 Piezoelectric actuator 12 Piezoelectric member 12A, 12B Piezoelectric element 13 Base member 15 Flexible wiring member 20 Common liquid chamber member 21 1st common liquid chamber member 22 2nd common liquid chamber member 25a, 25b Through hole for piezoelectric actuator 30 Vibration region 30a, 30b Convex part 40 Flow path member 41-45 Plate-shaped member 50 Circulation common liquid chamber 50a Groove 51 Fluid resistance 51a Through groove 52, 53 Circulation flow path 52a, 52b Through groove forming the fluid resistance section 53a, 53b, 53c, 53d Through groove forming the circulation flow path Groove 71 Supply port 71a Through hole 81 Circulation port 81a, 81b Through hole

(About FIGS. 10 to 12)
401 Guide member 403 Carriage 404 Liquid discharge head 405 Main scanning motor 406 Drive pulley 407 Driven pulley 408 Timing belt 410 Paper 412 Conveying belt 413 Conveying roller 414 Tension roller 416 Sub-scanning motor 417 Timing belt 418 Timing pulley 420 Maintenance / recovery mechanism 421 Cap member 422 Wiper member 440 Liquid discharge unit 491A, 491B Side plate 491C Back plate 493 Main scanning movement mechanism 494 Supply / circulation mechanism 495 Conveyance mechanism

Japanese Unexamined Patent Publication No. 2011-144348 Japanese Unexamined Patent Publication No. 2008-69355

Claims (5)

C. I. Pigment Red 122, C.I. I. Pigment Red 202, C.I. I. Pigment Red 209, and C.I. I. One or more pigments selected from Pigment Violet 19, quinacridone pigment, synergist with quinacridone skeleton, dispersant with polyoxyethylene structure and solubility parameter of 9.00 (cal / cm ³ ) ^1/2 or more 11.80 (Cal / cm ³ ) A method for producing an ink, which comprises a step of heat-treating a mixture containing an organic solvent of ^1/2 or less using a heater.
The content of the organic solvent with respect to the total amount of the ink is 30% by mass or more and 60% by mass or less.
A method for producing an ink in which the viscosity change rate before and after the sealing heating and the particle size change rate before and after heating are both −5% or more and 1% or less when the ink is sealed and heated at 80 ° C. for 4 weeks . Claimed that the organic solvent is one or more organic solvents selected from 3-butoxy-N, N-dimethylpropanamide, N, N-dimethyl-3-propaneamide and 3-ethoxy-N, N-dimethylpropanamide. Item 2. The method for producing an ink according to Item 1 . The method for producing an ink according to claim 1 or 2 , wherein the synergist is a sulfonic acid derivative of quinacridone . The method for producing an ink according to any one of claims 1 to 3, wherein the heat treatment is performed at 30 ° C. or higher in the heat treatment step. The method for producing an ink according to any one of claims 1 to 3, wherein the heat treatment is performed at 30 ° C. or higher and 80 ° C. or lower in the heat treatment step.

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