JPH107961A - Water-base ink and ink jet recording method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water-base ink which enables ink filling into a liq. room, air bubble removal, etc., to be done at a high reliability and can form a good image in printing on plain paper and to provide an ink jet recording method using the same. SOLUTION: This ink mainly comprises a colorant dispersible or soluble in water, water, and a humectant and satisfies the relation, 2.5ν+27.5<=γ<=2.5ν+47.5 wherein ν [Hz] is the air bubble frequency measured at 25 deg.C by the max. air bubble pressure method; 1<=ν<=5; and γ [mN/m] is the surface tension}.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-based ink suitable for ink-jet recording, in particular, a water-based ink having excellent ejection reliability, high image density on plain paper, and excellent image characteristics with little feathering and strike-through. Regarding ink.

[0002]

2. Description of the Related Art In recent years, ink jet printers have become popular because of their advantages such as low noise and low running cost, and color printers capable of printing on plain paper have also been put on the market. However, it is difficult to satisfy all characteristics such as image density, image color reproducibility, water resistance, light resistance, image drying property, image bleeding, image strikethrough and ejection reliability. Especially,
In order to ensure high image quality on plain paper and the reliability of ink jet ejection, wetting and penetrability of ink on plain paper, ink flow path members in ink jet recording apparatuses (hereinafter abbreviated as flow paths). The wettability and permeability of the ink to the ink must be controlled so as to be compatible, and the weight of the ink formulation due to various physical properties is extremely large. In JP-A-6-100808, an alkyl alcohol having 1 to 4 carbon atoms, and in JP-A-6-166841, a monohydric alcohol having 4 or less carbon atoms are added for the purpose of improving image quality. However, these alcohols have an odor and have problems in safety and long-term storage stability. JP-A-6-136306 discloses an ink to which a styrene-acrylic acid copolymer is added, but there is a problem that sufficient ejection reliability cannot be obtained with a fixed head type printer. . JP-A-6-10
No. 7,990, JP-A-6-322303,
Ink added with a specific surfactant by the applicant,
Although it is disclosed that it has excellent drying properties and little deterioration of image quality, it does not necessarily satisfy various characteristics, and at present, higher image density and reduced image bleeding are desired.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a water-based ink and a water-based ink capable of filling ink into a liquid chamber and discharging air bubbles with high reliability, and capable of forming a good image upon printing on plain paper. An object of the present invention is to provide an ink jet recording method using ink.

[0004]

A first feature of the present invention is that:
In an aqueous ink containing a colorant that is dispersed or dissolved in water, water and a wetting agent as main components, the maximum bubble pressure method is used.
The bubble frequency ν [Hz] of the ink measured at 5 ° C.
The water-based ink is characterized by satisfying the following condition with respect to the surface tension γ [mN / m]. Here, the bubble frequency is a parameter used when measuring the surface tension by the maximum bubble pressure method, and refers to the number of bubbles generated in units of one second.

## EQU2 ## When 1 ≦ ν ≦ 5, 2.5ν + 27.5 ≦ γ
.Ltoreq.2.5.nu. + 47.5 The upper limit of .gamma. Under the above conditions is a range necessary mainly for sufficiently wetting the flow path and obtaining ejection reliability. Above the upper limit condition, the upper limit of .gamma. In addition, the ability to fill the liquid chamber with ink and the ability to discharge bubbles are significantly deteriorated. Under the above conditions, γ
The lower limit is mainly less feathering on plain paper,
It is a range necessary for obtaining an image with a high reflection density, and below the lower limit condition, when it lands on plain paper, it diffuses irregularly, easily becoming an image lacking edge sharpness, and also in the depth direction. And the reflection density is difficult to obtain. Therefore, when the ink is in the above range, it exhibits excellent properties as an ink for inkjet.
A second feature of the present invention is that the first aqueous ink has a temperature of 30 ° C.
Is adjusted to 2 mPa · s or less, preferably 1.4 to 2.0 mPa · s. The viscosity of the aqueous ink is 2 mPa · s
When the size is larger than, the ejection failure of the nozzle is liable to occur, and although it is difficult to bleed on plain paper, the drying property is deteriorated. A third feature of the present invention is that in an ink jet recording method for ejecting ink in accordance with a recording signal to obtain an image, recording is performed at an ink jet recording frequency of 8 kHz or more, preferably 8 to 20 kHz using the aqueous ink. This is a characteristic inkjet recording method. In the present invention, by performing the inkjet recording method using the first and second aqueous inks at a frequency of 8 kHz or more, it is possible to achieve an effect that printing can be performed at a higher speed as compared with a case where the frequency is less than 8 kHz. . A fourth feature of the present invention is an ink jet recording method for ejecting ink in accordance with a recording signal to obtain an image.
To 250 g / m ² . In the present invention,
By performing the ink jet recording method using the first and second aqueous inks so that the ink adhesion amount is applied to plain paper, an effect that a good image can be formed can be obtained.

Hereinafter, the components constituting the aqueous ink of the present invention will be described in detail. <Colorant> Examples of the colorant include the following dyes and / or
Alternatively, pigments can be used alone or, if necessary, mixed. As the water-soluble dye to be used, a dye classified into an acid dye, a direct dye, a basic dye, a reactive dye and an edible dye in a color index and having excellent water resistance and light resistance is used. These are added to the extent that the effect is not alienated. If these dyes are specifically mentioned,
Acid dyes and food dyes C.I. I. Acid. Yellow 17,23,42,4
4,79,142 C.I. I. Acid. Red 1,8,13,14,1
8, 26, 27, 35, 37, 42, 52, 82, 8
7, 89, 92, 97, 106, 111, 114, 11
5,134,186,249,254,289 C.I. I. Acid. Blue 9,29,45,92,2
49 C.I. I. Acid. Black 1,2,7,24,2
6,94 C.I. I. hood. Yellow 3,4 C.I. I. hood. Red 7, 9, 14 C.I. I. hood. Black 1,2

As direct dyes, C.I. I. direct. Yellow 1,12,24,2
6,33,44,50,86,120,132,14
2,144 C.I. I. direct. Red 1,4,9,13,1
7, 20, 28, 31, 39, 80, 81, 83, 8
9,225,227 C.I. I. direct. Orange 26,29,62,1
02 C.I. I. direct. Blue 1,2,6,15,2
2,25,71,76,79,86,87,90,9
8,163,165,199,202 C.I. I. direct. Black 19,22,32,3
8, 51, 56, 71, 74, 75, 77, 154, 1
68,171

As basic dyes, C.I. I. basic. Yellow 1,2,11,13,
14, 15, 19, 21, 23, 24, 25, 28, 2
9, 32, 36, 40, 41, 45, 49, 51, 5
3,63,64,65,67,70,73,77,8
7, 91 C.I. I. basic. Red 2,12,13,14,
15, 18, 22, 23, 24, 27, 29, 35, 3
6,38,39,46,49,51,52,54,5
9, 68, 69, 70, 73, 78, 82, 102, 1
04, 109, 112 C.I. I. basic. Blue 1,3,5,7,9,2
1,22,26,35,41,45,47,54,6
2,65,66,67,69,75,77,78,8
9, 92, 93, 105, 117, 120, 122, 1
24, 129, 137, 141, 147, 155 C.I. I. basic. Black 2,8

As reactive dyes, C.I. I. Reactive. Black 3,4,7,11,
12, 17 C.I. I. Reactive. Yellow 1,5,11,1
3,14,20,21,22,25,40,47,5
1, 55, 65, 67 C.I. I. Reactive. Red 1,14,17,2
5,26,32,37,44,46,55,60,6
6, 74, 79, 96, 97 C.I. I. Reactive. Blue 1,2,7,14,1
5, 23, 32, 35, 38, 41, 63, 80, 95, etc. can be used.

As the pigment, azo-based, phthalocyanine-based, anthraquinone-based, quinacridone-based organic pigments,
Dioxazine-based, indigo-based, thioindigo-based, perylene-based, isoindolenone-based, aniline black, azomethine-based, rhodamine B lake pigment, carbon black, and the like.Examples of inorganic pigments include iron oxide, titanium oxide, calcium carbonate, and barium sulfate. Examples thereof include aluminum hydroxide, barium yellow, navy blue, cadmium red, chrome yellow, and metal powder. <Pigment dispersant> As a pigment dispersant, plant polymers such as gum arabic, gum tragan, guar gum, gum karaya, locust bean gum, arabinogalactone, pectin, quince seed starch, etc. , Algae-based polymers such as carrageenan and agar, animal-based polymers such as gelatin, casein, albumin, and collagen; microbial polymers such as xanthene gum and dextran; and semi-synthetic systems, methylcellulose, ethylcellulose, hydroxyethylcellulose, and hydroxypropylcellulose. , Carboxymethylcellulose and other cellulose-based polymers Starch-based polymers such as sodium starch glycolate and sodium starch phosphate Esters such as sodium alginate and propylene glycol alginate In the pure synthetic system, vinyl polymers such as polyvinyl alcohol, polyvinyl pyrrolidone and polyvinyl methyl ether, non-crosslinked polyacrylamide, polyacrylic acid and alkali metal salts thereof, acrylic resins such as water-soluble styrene acrylic resin, water-soluble Cationic styrene maleic acid resin, water-soluble vinyl naphthalene acrylic resin, water-soluble vinyl naphthalene maleic resin, polyvinyl pyrrolidone, polyvinyl alcohol, alkali metal salt of β-naphthalene sulfonic acid formalin condensate, quaternary ammonium and amino groups Examples include a polymer compound having a salt of a functional group in a side chain, and a natural polymer compound such as shellac.

In the ink of the present invention, the following organic solvents can be used for the purpose of preventing drying of the ink and improving the dissolution stability. Ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, 1,5-pentanediol, 1,
6-hexanediol, glycerol, 1,2,6-hexanetriol, 1,2,4-butanetriol,
Polyhydric alcohols such as 1,2,3-butanetriol and petriol, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, propylene glycol Polyhydric alcohol alkyl ethers such as monoethyl ether; polyhydric alcohol aryl ethers such as ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether;
-Methyl-2-pyrrolidone, N-hydroxyethyl-2
Nitrogen-containing heterocyclic compounds such as -pyrrolidone, 2-pyrrolidone, 1,3-dimethylimidazolidinone, ε-caprolactam, formamide, N-methylformamide, N, N
Amides such as dimethylformamide, monoethanolamine, diethanolamine, triethanolamine,
Monoethylamine, diethylamine, amines such as triethylamine, dimethyl sulfoxide, sulfolane, sulfur-containing compounds such as thiodiethanol, and propylene carbonate, ethylene carbonate, γ-butyrolactone and the like,
A plurality of the organic solvents may be mixed and used for the purpose of making the ink of the present invention have desired physical properties, preventing drying of the ink, and improving dissolution stability.

<Penetrant> Examples of the penetrant include the following compounds. Anionic surfactants such as polyoxyethylene alkyl ether acetate, dialkyl sulfosuccinic acid having an alkyl chain having 5 to 7 carbon chains which may be branched, etc. Acetylene glycol, polyoxyethylene nonyl phenyl ether, polyoxyethylene alkyl Nonionic surfactants such as ethers Polyhydric alcohols such as diethylene glycol monophenyl ether, ethylene glycol monophenyl ether, ethylene glycol monoallyl ether, diethylene glycol monophenyl ether, diethylene glycol monobutyl ether, propylene glycol monobutyl ether, and tetraethylene glycol chlorophenyl ether Alkyl and aryl ethers of fluorine surfactants, silicon surfactants, ethanol, 2-propane Lower alcohols such Lumpur,

The ink of the present invention may contain conventionally known additives in addition to the coloring agent and the solvent.
For example, preservatives and fungicides include sodium dehydroacetate, sodium sorbate, 2-pyridinethiol-1
-Sodium oxide, sodium benzoate, sodium pentachlorophenol, benzisothiazoline-
3-ones and the like can be used in the present invention. As a pH adjuster, the pH is adjusted to 7 without adversely affecting the ink to be prepared.
Any substance that can be adjusted as described above can be used. Examples thereof include amines such as diethanolamine and triethanolamine, hydroxides of alkali metal elements such as lithium hydroxide, sodium hydroxide and potassium hydroxide, ammonium hydroxide, quaternary ammonium hydroxide, and quaternary phosphonium. Hydroxide, lithium carbonate,
Examples thereof include alkali metal carbonates such as sodium carbonate and potassium carbonate. Examples of the chelating reagent include sodium ethylenediaminetetraacetate, sodium nitrilotriacetate, sodium hydroxyethylethylenediaminetriacetate, sodium diethylenetriaminepentaacetate, and sodium uramildiacetate. Examples of the rust inhibitor include acidic sulfite, sodium thiosulfate, ammonium thiodiglycolate, diisopropylammonium nitrite, pentaerythritol tetranitrate, dicyclohexylammonium nitrite and the like. Examples of the anti-clogging agent include urea derivatives such as urea and hydroxyethylurea. Other water-soluble UV absorbers depending on the purpose,
A water-soluble infrared absorber can also be added.

[0013]

EXAMPLES Examples of the present invention and comparative examples are shown below.

Example 1 A composition having the following formulation was stirred and dissolved at 60 ° C., and allowed to cool at room temperature.
It was adjusted with an aqueous solution, and this was filtered through a 0.22 μm Teflon filter to prepare Ink 1. FIG. 1 shows the relationship between the bubble frequency ν [Hz] of this ink 1 and the surface tension γ [mN / m]. C. I. Direct Black 168 3% by weight 2-Pyrrolidone 3% by weight Diethylene glycol 4% by weight Glycerin 1% by weight ECTD-3NEX 0.1% by weight (Surfactant manufactured by Nippon Surfactant Chemical Co.) Nonipol 400 (Surfactant manufactured by Sanyo Chemical) 0. 5% by weight Sun-I-back P-100 (Antifungal and antiseptic agent manufactured by Sanai Petroleum) 0.4% by weight Deionized water balance

Example 2 An ink 2 was prepared in the same manner as in Example 1 except that the following composition was used. C. I. Direct Black 168 3% by weight 2-Pyrrolidone 2% by weight Diethylene glycol 2% by weight Glycerin 1% by weight ECTD-3NEX 0.12% by weight (Surfactant manufactured by Nippon Surfactant Chemical Co.) Nonipol 400 (Surfactant manufactured by Sanyo Chemical) 0. 5% by weight Sun-I-back P-100 (Antifungal and antiseptic agent manufactured by Sanai Petroleum) 0.4% by weight Deionized water balance

Example 3 An ink 3 was prepared in the same manner as in Example 1 except that the following composition was used. C. I. Direct Black 168 3% by weight 2-Pyrrolidone 2% by weight Diethylene glycol 3% by weight Glycerin 1% by weight ECTD-3NEX 0.08% by weight (Surfactant manufactured by Nippon Surfactant Chemical Co.) Nonipol 400 (Surfactant manufactured by Sanyo Chemical) 0. 5% by weight Sun-I-back P-100 (Antifungal and antiseptic agent manufactured by Sanai Petroleum) 0.4% by weight Deionized water balance

Example 4 An ink 4 was prepared in the same manner as in Example 1 except that the following composition was used. C. I. Direct Black 168 3% by weight 2-Pyrrolidone 3% by weight Diethylene glycol 4% by weight Glycerin 1% by weight ECTD-3NEX 0.1% by weight (Surfactant manufactured by Nippon Surfactant Chemical) Nonipol 400 (Surfactant manufactured by Sanyo Chemical) 1% % San-Ivac P-100 (Antiseptic / antifungal agent manufactured by Sanai Petroleum) 0.4% by weight Deionized water balance

Example 5 An ink 5 was prepared in the same manner as in Example 1 except that the following composition was used. PROJET FASTBLACK2 3% by weight (dye manufactured by ZENECA) 2-Pyrrolidone 4% by weight Diethylene glycol 3% by weight Glycerin 1% by weight ECTD-3NEX 0.1% by weight (Surfactant manufactured by Nippon Surfactant Chemical Co.) Nonipol 400 (Sanyo Chemical Co., Ltd.) Agent) 0.1% by weight Sun-eye back P-100 (preservative and fungicide made by Sanai Petroleum) 0.4% by weight Deionized water balance

Comparative Example 1 Ink 6 was prepared in the same manner as in Example 1 except that ECTD-3NEX (a surfactant manufactured by Nippon Surfactant Chemical Co., Ltd.) was not added.

Comparative Example 2 Ink 7 was prepared in the same manner as in Example 2 except that BT7 (a surfactant manufactured by Nikko Chemicals) was added instead of ECTD-3NEX (a surfactant manufactured by Nippon Surfactant Chemical Co.).

Comparative Example 3 Ink 8 was prepared in the same manner as in Example 3, except that the amount of ECTD-3NEX (Surfactant manufactured by Nippon Surfactant Chemical Co., Ltd.) was changed to 2% by weight.

Comparative Example 4 Ink 9 was prepared in the same manner as in Example 5 except that diethylene glycol monobutyl ether was added in an amount of 15% by weight instead of diethylene glycol.

The following tests were performed on the inks of Examples 1 to 5 and Comparative Examples 1 to 5, and the results are shown in Table 1 below. Surface tension measurement The surface tension γ of the ink at a bubble frequency ν = 1 to 5 Hz was measured at 25 ° C. using a Sensa Dyne 6000 liquid surface tensiometer manufactured by Ebara Densan Co., Ltd. Outside is marked with x. Viscosity measurement Using Toki Sangyo R-type viscometer series 500, 30 ° C
The viscosity η having a stable value was measured at a rotation speed at which the shear rate of the standard cone was 50% or more. Image quality Nozzle diameter 32μ using laminated PZT for pressurizing the liquid chamber flow path
m, recording frequency 16 kHz having a nozzle of 600 dpi
Printing was performed using an ink jet printer of z, and image bleeding, density, and solid filling were visually judged comprehensively. O, △, and × were given from the best one. The printing paper was printed on ten types of commercially available plain paper including recycled paper, woodfree paper, and bond paper. At this time, the ink adhesion amount to plain paper is 16
To 17 g / m ² . Reliability during printing suspension Check how much printing can be resumed without capping, cleaning, etc. during the operation of the above printer, and check the deviation of the ejection direction or the change in the weight of the ejected droplets. Was evaluated. △, Δ, and × were given because of reliability.

[0024]

[Table 1]

[0025]

【effect】

1. (1) Due to the excellent wettability to the ink flow path, ink can be filled into the liquid chamber and bubbles can be discharged with high reliability. In addition, due to appropriate wettability and permeability on plain paper, a good image is provided in printing. 2. Claim 2 It is possible to obtain excellent ejection reliability and good drying properties on plain paper. 3. (3) By using the water-based ink of (1) and (2) for an ink jet ink, it is possible to cope with a high recording frequency and to perform high-speed printing.

[Brief description of the drawings]

FIG. 1 is a diagram showing a relationship between a bubble frequency ν and a surface tension γ.

[Explanation of symbols]

 A Relationship between bubble frequency ν and surface tension γ of ink 1

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masato Igarashi 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company (72) Inventor Akiko Konishi 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Inside Ricoh Company (72) Inventor Hirotaka Mochizuki 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Company Ricoh Company (72) Inventor Takanori Tsukiki 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Company Ricoh Company (72) Inventor Ikuko Yamada 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd.

Claims (4)

[Claims] 1. In an aqueous ink containing a colorant, water and a wetting agent dispersed or dissolved in water as main components, a bubble frequency ν of the ink measured at 25 ° C. by a maximum bubble pressure method.
A water-based ink characterized in that the relationship between [Hz] and surface tension γ [mN / m] satisfies the following conditions. [Expression 1] When 1 ≦ ν ≦ 5, 2.5ν + 27.5 ≦ γ
≦ 2.5ν + 47.5 2. The viscosity η measured at 30 ° C. is 2 mPa · s
The aqueous ink according to claim 1, wherein the aqueous ink is adjusted as follows. 3. An ink jet recording method for ejecting ink in accordance with a recording signal to obtain an image, wherein the aqueous ink according to claim 1 is used to record at an ink jet recording frequency of 8 kHz or more. Ink jet recording method. 4. An ink jet recording method for ejecting ink in accordance with a recording signal to obtain an image, wherein the aqueous ink according to claim 1 or 2 is used to reduce the amount of ink adhered to plain paper from 2.5 to 250 g / m. ^2. An ink jet recording method characterized by recording in the range of ² .