JP2000319560A - Color ink for inkjet recording - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a color ink for ink-jet recording that can shorten the color-stabilizing time on the recording medium, has high moistureproofness and can secure the ink-jetting stability, thereby attains higher quality of recording in an ink jetting recorder that loads two or more levels of inks different in the concentration of a similar color tone using the concentration gradation in the addition to the conventional areal gradation. SOLUTION: This color ink for color jetting comprises at least water, dyes, a penetrating agent, a hydrophilic low-volatile and high boiling organic solvent. In the dilute ink with a dye concentration of 0.1-3 wt.%, the hydrophilic low volatile, high-boiling organic solvent is prepared by mixing a hydrophilic low volatile, high-boiling organic solvent having a vapor pressure of <=1 Pa at 20 deg.C with a hydrophilic low volatile, high-boiling organic solvent having a vapor pressure of 1-10 Pa at 20 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink used for ink-jet recording, and more particularly to a method of discharging a plurality of color inks composed of two or more levels of ink of the same system and different shades onto a recording medium. The present invention relates to a color ink used for inkjet recording for forming an image on a recording medium.

[0002]

2. Description of the Related Art Ink jet recording is a method of discharging ink as small droplets from fine nozzles to record characters and figures on a recording medium. As an inkjet recording method, an electric signal is converted into a mechanical signal using a piezo element,
A method of recording characters and symbols on a recording medium by intermittently discharging the ink stored in the recording head, and rapidly heating a part of the ink stored in the recording head that is very close to the discharge to generate bubbles. In addition, a method of recording characters and symbols on a recording medium by ejecting intermittently due to volume expansion due to the bubbles has been put to practical use.

As inks for ink jet recording, those using water as a main solvent are predominant because of high safety and low cost. Various hydrophilic, low-volatile, high-boiling organic solvents and the like are added in order to prevent nozzle clogging and ensure ejection reliability. Further, as a coloring agent, a coloring agent using a dye is mainly used from the viewpoint of good coloring property and storability as an ink (particularly, color ink).

[0004] Inks used for ink-jet recording are required to have characteristics such as good drying property of printing and little blurring of printing (color blurring).

[0005] In order to satisfy these requirements, conventional ink jet recording inks have been devised to allow the ink to quickly penetrate into a recording medium. US Patent 5,15
As described in US Pat. No. 6,675, diethylene glycol monobutyl ether is added.
No. 502 or Japanese Patent Application Laid-Open No. 56-5871 discloses the addition of Surfynol 465 (manufactured by Air Products), which is an acetylene glycol-based surfactant, or US Pat. No. 5,196,056. As described in the specification, 1.5 to 5
For example, the addition of 1 to 3 wt% of wt% and Surfynol 465 is being studied.

In recent years, an ink jet recording method for obtaining higher quality recording by using two or more levels of inks of the same system and having different shades and using density gradation in addition to the conventional area gradation. Has been proposed.

[0007]

In evaluating a conventional color ink for ink-jet recording using a dye, the color hue was measured for several tens of minutes after recording on a recording medium and for several days after recording. Was observed to occur.

This is a phenomenon that occurs because the hydrophilic, low-volatile, high-boiling organic solvent added to prevent nozzle clogging and ensure discharge reliability remains without being volatilized on the recording medium. , Delay the color stabilization time of the ink,
This is a cause of deteriorating moisture resistance. FIG. 1 is a schematic diagram showing a state until the color is stabilized by the amount of a hydrophilic low-volatile high-boiling organic solvent added. When the color difference was confirmed based on the sample in which the color was stable, the color stabilization time on the recording medium was shortened by reducing the amount of the hydrophilic low-volatile high-boiling organic solvent.

However, if the hydrophilic low-volatile high-boiling organic solvent is removed from the ink composition in order to shorten the color stabilization time on the recording medium, it becomes difficult to ensure ejection reliability due to clogging and the like.

Therefore, the present invention is to solve such a problem, and an object of the present invention is to mount two or more levels of inks of the same system and different in shades, in addition to the conventional area gradation. In the ink jet recording method capable of obtaining higher quality recording by using the density gradation, the color stabilization time on the recording medium is short, the moisture resistance is good, and the ink jet recording stability can be secured. It is to provide a color ink for recording.

[0011]

Means for Solving the Problems The color ink for ink-jet recording of the present invention has two colors of the same system and different in shade.
In a color ink for inkjet recording that forms a color image on a recording medium by discharging a plurality of color inks composed of inks of a level or higher onto the recording medium, at least,
A hydrophilic low-volatile high-boiling organic solvent containing water, a dye, a penetrant, a hydrophilic low-volatile high-boiling organic solvent having a vapor pressure of 1 Pa or less at 20 ° C. and a vapor pressure of 1 to 10 P at 20 ° C.
a light ink obtained by mixing a hydrophilic, low-volatility, high-boiling-point organic solvent a).

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The ink jet recording color ink of the present invention is equipped with two or more levels of inks of the same system and different shades, and furthermore, by using density gradation in addition to the conventional area gradation, furthermore, In an ink jet recording method capable of obtaining high-quality recording, characteristics such as a short color stabilization time on a recording medium, good moisture resistance, and ensuring ejection stability are required. Attention was paid to the result of intensive studies.

Conventionally, ink solvents have low viscosity, excellent safety, easy handling,
Water is mainly used because of its low cost and no odor. As the ink used, ultrapure water that has undergone a purification step such as ion exchange or distillation is preferable.

The dyes used in the present invention include direct dyes, acid dyes, food dyes, basic dyes, reactive dyes, disperse dyes, vat dyes, soluble vat dyes, reactive disperse dyes, and oil dyes. Any of them can be used, and among them, a water-soluble dye is preferably used in terms of ink performance. I. Direct Yellow 8, 9, 11, 12, 2
7, 28, 29, 33, 35, 39, 41, 44, 5
0, 53, 58, 59, 68, 86, 87, 93, 9
5, 96, 98, 100, 106, 108, 109, 1
10, 130, 132, 142, 144, 161, 16
3, C.I. I. Direct Red 2, 4, 9, 23, 26, 3
1, 39, 62, 63, 72, 75, 76, 79, 8
0, 81, 83, 84, 89, 92, 95, 111, 1
73, 184, 207, 211, 212, 214, 21
8, 221, 223, 224, 225, 226, 22
7,232,233,240,241,242,24
3, 247, C.I. I. Direct violet 7, 9, 47, 48,
51, 66, 90, 93, 94, 95, 98, 100,
101, C.I. I. Direct Blue 1, 10, 15, 22, 2
5, 55, 67, 68, 71, 76, 77, 78, 8
0, 84, 86, 87, 90, 98, 106, 108,
109, 151, 156, 158, 159, 160, 1
68, 189, 192, 193, 194, 199, 20
0, 201, 202, 203, 207, 211, 21
3, 214, 218, 225, 229, 236, 23
7, 244, 248, 249, 251, 252, 26
4, 270, 280, 288, 289, 291, C.I. I. Acid Yellow 17, 19, 23, 25, 3
9, 40, 42, 44, 49, 50, 61, 64, 7
6, 79, 110, 127, 135, 143, 151,
159, 169, 174, 190, 195, 196, 1
97, 199, 218, 219, 222, 227; I. Acid Red 35, 42, 52, 57, 6
2, 80, 82, 111, 114, 118, 119, 1,
27, 128, 131, 143, 151, 154, 15
8, 249, 254, 257, 261, 263, 26
6,289,299,301,305,336,33
7, 361, 396, 397, C.I. I. Acid Violet 5, 34, 43, 47,
48, 90, 103, 126, C.I. I. Acid Blue 9, 25, 40, 41, 62,
72, 76, 78, 80, 82, 92, 106, 11
2, 113, 120, 127, 129, 138, 14
3, 175, 181, 205, 207, 220, 22
1, 230, 232, 247, 258, 260, 26
4, 271, 277, 278, 279, 280, 28
8, 290, 326; I. Reactive Yellow 2, 3, 13, 14, 1
5, 17, 18, 23, 24, 25, 26, 27, 2,
9, 35, 37, 41, 42, C.I. I. Reactive Red 3, 13, 17, 19, 2
1, 22, 23, 24, 29, 35, 37, 40, 4
1, 43, 5, 49, 55, 180 C.I. I. Reactive Violet 1, 3, 4, 5,
6, 7, 8, 9, 16, 17, 22, 23, 24, 2,
6, 27, 33, 34, C.I. I. Reactive Blue 2, 3, 5, 8, 10, 1
3, 14, 15, 17, 18, 19, 21, 25, 2
6, 27, 28, 29, 38, C.I. I. Basic Yellow 1, 2, 4, 11, 13,
14, 15, 19, 21, 23, 24, 25, 28, 2
9, 32, 36, 39, 40, C.I. I. Basic Red 12, 13, 14, 15, 1
8, 22, 23, 24, 25, 27, 29, 35, 3,
6, 38, 39, 45, 46, C.I. I. Basic violet 1, 2, 3, 7, 1
0, 15, 16, 20, 21, 25, 27, 28, 3
5, 37, 39, 40, 48, C.I. I. Basic Blue 1, 3, 5, 7, 9, 22,
26, 41, 45, 46, 47, 54, 57, 60, 6
2, 65, 66, 69, 71, and the like.

The amount of the dye varies depending on the type of the dye and the desired coloring property.
It is often used in an amount of about 10 wt%. In order to obtain higher image quality, two or more levels of inks of the same system with different shades are installed, and when density tone is used in addition to the conventional area tone, the dark ink is the same as the above case. Although the amount of addition is about the same, the amount of addition is smaller for light ink, and it is often used at about 0.1 to 3 wt%. The smaller the amount of the dye added to the light ink, the lower the visibility of the dots in the low-density region of the recorded image, so that the roughness of the image can be suppressed.

However, if the density difference between the light ink and the dark ink becomes large, the density jump becomes large at the connection between the light ink and the dark ink in the process of shifting from the low density area to the high density area of the recorded image. However, it becomes difficult to suppress the roughness at that portion. Therefore, the amount of dye added to the light ink is 20 times the amount of dye added to the dark ink.
% Is preferable. Also, since the difference in shading can be set smaller as the shading level increases, the image quality becomes smoother in the process of shifting from the low density area to the high density area of the recorded image, and the dye addition amount of the lightest light ink is reduced. Since the density can be reduced, it is possible to eliminate roughness in a low density area of a recorded image.

However, unnecessarily increasing the number of types of ink involves increasing the size and cost of a system such as a recording head and ink supply. Therefore, it is preferable to perform the shading at two to three levels.

Examples of the penetrant used in the present invention include ethylene glycol alkyl ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, Triethylene glycol monobutyl ether or the like is used.

Further, a surfactant can be used as a penetrant used in the ink of the present invention.

For example, as anionic surfactants, higher fatty acid salts, higher alkyl dicarboxylates, higher alcohol sulfates, higher alkyl sulfonates, alkylbenzene sulfonates, alkyl naphthalene sulfonates, salts of naphthalene sulfonates ( Na, K, Li, C
a) Polycondensate of formalin, condensate of higher fatty acid and amino acid, dialkyl sulfosuccinate, alkyl sulfosuccinate, naphthenate, etc., alkyl ether carboxylate, acylated peptide, α-olefin sulfonate, N -Acyl methyl taurine, alkyl ether sulfate, secondary higher alcohol ethoxy sulfate,
Polyoxyethylene alkyl phenyl ether sulfate,
Monoglycosulfate, alkyl ether phosphate, alkyl phosphate and the like.

Examples of the cationic surfactant include an aliphatic amine salt, a quaternary ammonium salt, a sulfonium salt, and a phosphonium salt.

Examples of the amphoteric surfactant include carboxybetaine type, aminocarboxylate, lecithin and the like.

Examples of the nonionic surfactant include acetylene glycol-based, fluorine-based, silicon-based, acrylic acid copolymer, polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, polyoxyethylene secondary alcohol ether, and polyoxyethylene. Sterol ether, polyoxyethylene lanolin derivative,
Ethylene oxide derivative of alkylphenol formalin condensate, polyoxyethylene polyoxypropylene block polymer, fatty acid ester type of polyoxyethylene polyoxypropylene alkyl ether polyoxyethylene compound, polyethylene oxide condensed polyethylene glycol fatty acid ester, fatty acid monoglyceride, polyglycerin fatty acid Esters, sorbitan fatty acid esters, propylene glycol fatty acid esters, sucrose fatty acid esters, fatty acid alkanolamides, polyoxyethylene fatty acid amides, polyoxyethylene alkylamine alkylamine oxides and the like.

Examples of the hydrophilic high-boiling low-volatile solvent having a vapor pressure of 1 Pa or less at 20 ° C. used in the ink of the present invention include glycerin, triethylene glycol, and polyethylene glycol (preferably having an average molecular weight of about 200 to 400). . Such a hydrophilic high-boiling-point low-volatile solvent having a vapor pressure of 1 Pa or less has almost no volatilization at room temperature and also has a hygroscopic property, so that it is an effective additive for preventing clogging of ink. However, the vapor pressure is 1P
The hydrophilic high-boiling point low-volatile solvent of a or less will remain on the recording medium forever and suppress the evaporation of water,
It takes time to stabilize the color on the recording medium, and in an environment with high humidity, the dye fixed on the recording medium oozes out due to moisture absorption. In order to suppress such a phenomenon, it is preferable that the amount added to the ink be 5 wt% or less. However, 1w
It is preferable to add t% or more.

Further, a hydrophilic high-boiling low-volatile solvent having a vapor pressure of 1 Pa or less at 20 ° C. is used in an amount of 1 to 5 wt.
%, It is not possible to sufficiently suppress the evaporation of water from the nozzles during printing, and therefore, a short-term increase in the viscosity of ink tends to cause ejection failure. Therefore, in the present invention, the vapor pressure at 20 ° C. is 1 Pa
These problems have been solved by using a mixture of the following hydrophilic high-boiling low-volatile solvent and a hydrophilic high-boiling low-volatile solvent having a vapor pressure of 1 to 10 Pa at 20 ° C.

Examples of the hydrophilic high-boiling low-volatile solvent having a vapor pressure of 1 to 10 Pa at 20 ° C. include ethylene glycol, diethylene glycol, dipropylene glycol,
Hexylene glycol, 1,3-butanediol, 1,
5-pentanediol, triethanolamine and the like. Such a hydrophilic high-boiling low-volatile solvent having a vapor pressure of 1 to 10 Pa at 20 ° C has a vapor pressure of 1 at 20 ° C.
Since it is a hydrophilic high-boiling-point low-volatile solvent of Pa or less and eventually volatilizes on a recording medium, it hardly affects the moisture resistance of a recorded image. However, if the addition amount is too large, the color stabilization time is extended, and if the addition amount is too small, it becomes difficult to secure the ejection stability.
About 20 wt% is preferable.

As described above, the vapor pressure at 20 ° C. is 1P
a) a method of using a mixture of a hydrophilic high-boiling low-volatile solvent having a high boiling point and a low-volatile solvent having a vapor pressure at 20 ° C. of 1 to 10 Pa to shorten the color stabilization time on a recording medium; In addition, it is possible to suppress ejection failure due to clogging and a short-term increase in ink viscosity. However, in the case of a dark ink having a dye concentration of more than 3 wt%, a sufficient effect on clogging or the like may not be obtained with the above-mentioned amount of addition, and therefore, particularly, a hydrophilic ink having a vapor pressure at 20 ° C. of 1 Pa or less is used. It is necessary to add a large amount of a low boiling point volatile solvent. Therefore, it is difficult to shorten the color stabilization time of the dark ink, and it is difficult to increase the moisture resistance of the recorded image.
However, light inks having a dye concentration of 0.1 to 3 wt% are used in most of the color reproduction range actually used, and by using the light ink as the ink of the present invention, sufficient light can be obtained for most image data. It was confirmed that a significant effect was obtained.

As other components, additives such as a preservative, an antioxidant, a conductivity adjuster, a pH adjuster, a surface tension adjuster, and an oxygen absorber can be appropriately used.

For example, sodium benzoate, sodium pentachlorophenol, sodium 2-pyridinethiol-1-oxide, sodium sorbate, sodium dehydroacetate, 1,2-dibenzisothiazolin-3-one as preservatives and fungicides (Proxel CRL, Proxel BDN, Proxel GX manufactured by ZENECA Corporation)
L, Proxel XL-2, Proxel TN) and the like may be added.

Examples of the ink jet recording color ink used in the present invention will be described below. The unit of the numerical value of the composition ratio is wt%.

Example 1 (Dark Yellow Ink) <Composition Ratio> I. Direct Yellow 132 3.5 Triethylene glycol monobutyl ether 10 Surfynol 465 (manufactured by Air Products Co., Ltd.) 1 Diethylene glycol 10 Glycerin 10 Potassium hydroxide 0.1 Proxel XL-2: Preservative (ZENECA ( 0.3) Benzotriazole: corrosion inhibitor (manufactured by Kanto Chemical Co., Ltd.) 0.01 Ultrapure water 65.09 Total 100 (light yellow ink) <Composition ratio> I. Direct Yellow 132 1 • Triethylene glycol monobutyl ether 10 • Surfynol 465 (manufactured by Air Products) 1 • Diethylene glycol 5 • Glycerin 1 • Potassium hydroxide 0.1 • Proxel XL-2: Preservative (ZENECA Corporation) 0.3) Benzotriazole: Corrosion inhibitor (manufactured by Kanto Chemical Co., Ltd.) 0.01 Ultrapure water 81.59 total 100 (concentrated magenta ink) <Composition ratio> I. Reactive Red 180 3.5 Triethylene glycol monobutyl ether 10 Surfynol 465 (produced by Air Products Co., Ltd.) 1 Diethylene glycol 10 Glycerin 10 Potassium hydroxide 0.1 Proxel XL-2: Preservative (ZENECA) 0.3) Benzotriazole: Corrosion inhibitor (Kanto Chemical Co., Ltd.) 0.01 Ultrapure water 65.09 Total 100 (light magenta ink) <Composition ratio> I. Reactive Red 180 1 Triethylene glycol monobutyl ether 10 Surfynol 465 (manufactured by Air Products Co., Ltd.) 1 Diethylene glycol 5 Glycerin 1 Potassium hydroxide 0.1 Proxel XL-2: Preservative (ZENECA (trade name) )) 0.3 • Benzotriazole: Corrosion inhibitor (Kanto Chemical Co., Ltd.) 0.01 • Ultrapure water 81.59 total 100 (concentrated cyan ink) <Composition ratio> I. Direct Blue 199 3.5 Triethylene glycol monobutyl ether 10 Surfynol 465 (manufactured by Air Products Co., Ltd.) 1 Diethylene glycol 10 Glycerin 10 Potassium hydroxide 0.1 Proxel XL-2: Preservative (ZENECA ( 0.3) Benzotriazole: corrosion inhibitor (Kanto Chemical Co., Ltd.) 0.01 Ultrapure water 65.09 Total 100 (light cyan ink) <Composition ratio> I. Direct Blue 199 1-Triethylene glycol monobutyl ether 10-Surfynol 465 (manufactured by Air Products) 1-Diethylene glycol 5-Glycerin 1-Potassium hydroxide 0.1-Proxel XL-2: Preservative (ZENECA, Inc.) 0.3) Benzotriazole: Corrosion inhibitor (Kanto Chemical Co., Ltd.) 0.01 Ultrapure water 81.59 total 100 <Example 2> Based on the ink composition of Example 1, The amount of glycerin added was changed to 5 wt%, and the amount was adjusted with ultrapure water.

Example 3 Based on the ink composition of Example 1, glycerin in the light ink was changed to polyethylene glycol having an average molecular weight of 300.

Example 4 Based on the ink composition of Example 1, diethylene glycol in the light ink was changed to hexylene glycol.

The following is a comparative example of the present invention.

Comparative Example 1 Based on the ink composition of Example 1, the addition amount of glycerin in the light ink was changed to 0.5 wt%, and the amount was adjusted with ultrapure water.

Comparative Example 2 Based on the ink composition of Example 1, the addition amount of glycerin in the light ink was changed to 10 wt%, and the amount was adjusted with ultrapure water.

Comparative Example 3 Based on the ink composition of Example 1, the addition amount of diethylene glycol in the light ink was 0 wt.
% And adjusted with ultrapure water.

Comparative Example 4 Based on the ink composition of Example 1, glycerin and diethylene glycol of the light ink were changed to 0 wt%, and the amount was adjusted with ultrapure water.

Next, the evaluation items will be described. In the evaluation of the present invention, PM-770C (manufactured by Seiko Epson Corporation) was improved for evaluation, and each evaluation was performed using a recording mechanism capable of adjusting dot weight and color balance for each ink. Table 1 shows a list of evaluation results. The results of each evaluation were classified by a 10-point scale, and the best product was scored as 10 points.

[0040]

[Table 1]

<Evaluation of Color Stability> A composite black was printed with a light ink, and the color was measured over time. For color measurement, a Gretag spectrophotometer SPM50 (GR
ETAG Co., Ltd.) was used. Photoprint paper 2 (manufactured by Seiko Epson Corporation) was used as a recording medium. Here, the reason for using composite black is
This is because the change in hue is more remarkable than in the case of recording with each light ink single color.

The color of the recording sample was measured while drying in an environment of 25 ° C. and 20% RH. The time until the color difference ΔE was less than 2 was confirmed based on the data for one week after printing.

<Evaluation of Moisture Resistance> High-definition color digital standard image data (ISO / JIS-SCID JISX 9)
Sample number 1 of JSA-00001)
8 was printed and dried for one week in an environment of 25 ° C. and 20% RH, then left at 40 ° C. and 85% RH for 3 days, and the color change of the recorded sample in a high humidity environment was observed. Photo print paper 2 (manufactured by Seiko Epson Corporation) as a recording medium
It was used.

<Evaluation of clogging recovery property>
It was left for 3 months in an environment of 20% RH to confirm the retrievability of nozzle clogging.

<Evaluation of Discharge Stability> High-definition color digital standard image data (ISO / JIS-SCID JISX)
Sample No. 14 (color chart) of 9201 compliant (JSA-00001) was printed continuously for 100 pages.
The printing environment was at 25 ° C. and 20% RH.

The ink jet recording apparatus normally discharges the ink whose viscosity has increased near the nozzle at a certain interval to a place other than the recording medium (such as a head cap) (hereinafter, referred to as a discharge stabilizing operation). Discharge failure due to an increase in the viscosity of the ink. The required ejection amount during the ejection stabilization operation was adjusted so as not to cause dot disturbance or omission in the above continuous printing. The smaller the required ejection amount, the better the ejection stability.

According to the color ink set for inkjet recording according to the present invention, excellent results can be obtained for various characteristics required for inkjet recording. Further, in the comparative example, there was a low result in any of the evaluation items, and the balance was lost.

[0048]

As described above, according to the ink jet recording color ink of the present invention, two or more inks of the same system and different in shading are mounted, and in addition to the conventional area gradation, the density gradation is obtained. By using the tone, in an ink jet recording method capable of obtaining higher quality recording, the color stabilization time on the recording medium is short, the moisture resistance is good, and the discharge stability can be secured.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a state until a color is stabilized by the addition amount of a hydrophilic low-volatile high-boiling organic solvent.

Claims (4)

[Claims] 1. An ink jet recording color ink for forming a color image on a recording medium by discharging a plurality of color inks composed of two or more levels of inks of different colors and shades of the same system onto a recording medium, Contains water, dye, penetrant, hydrophilic, low-volatility, high-boiling organic solvent, 2
A light ink obtained by mixing a hydrophilic low-volatile high-boiling organic solvent having a vapor pressure of 1 Pa or less at 0 ° C. and a hydrophilic low-volatile high-boiling organic solvent having a vapor pressure of 1 to 10 Pa at 20 ° C. Color ink for inkjet recording. 2. The dye concentration of the light ink is 0.1 to 3 watts.
2. The color ink for inkjet recording according to claim 1, wherein the content is t%. 3. The ink jet recording apparatus according to claim 1, wherein the amount of the hydrophilic low-volatile high-boiling organic solvent having a vapor pressure of 1 Pa or less at 20 ° C. is 1 to 5 wt%. Color ink. 4. The addition amount of a hydrophilic low-volatile high-boiling organic solvent having a vapor pressure of 1 to 10 Pa at 20 ° C. is 5 to 20 wt.
%. The color ink for inkjet recording according to claim 1, wherein