JPH11116869A - Ink for ink jet recording - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject product hardly causing the clogging of ink jet printers due to the dryness of the ink, not generating the coagulation and precipitation of the ink over a long period, capable of being stably extruded, and excellent in water resistance, light resistance and the like by combining the polymer of a flavonoid and/or an indole quinone with an organic pigment in a specific ratio. SOLUTION: This ink contains (A) 0.1-10% of the polymer of a flavonoid (preferably a catechin derivative or the like) and/or an indole quinone (preferably melamine) and (B) 0.5-20% of an organic pigment. A surfactant and/or a water-soluble resin may combinedly be used as dispersion auxiliaries for the component B in the objective product. On the preparation of the objective product, it is preferable to remove coarse particles. For example, the product not causing the clogging of printers is obtained by filtering a compounded ink with a pressure filtration machine using a 1 μm filter to remove particles having sizes of >=1 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink-jet recording ink which has excellent ejection stability in an ink-jet printer and can realize robust printing.

[0002]

2. Description of the Related Art In a conventional ink jet recording system, recording is performed by generating and ejecting ink droplets and attaching the ink droplets to a recording medium. When a water-soluble dye is used as a coloring agent for the ink used in this recording method, it is excellent in clogging resistance and the like, but has problems in water resistance and light resistance. In order to solve such problems of the dye ink, various inks using a pigment as a colorant have been proposed. JP-B-62-1426 discloses an example of such a pigment ink.
JP-A-2-255875, JP-A-4-18462
In the publication, an ink that solves the problems of water resistance and light resistance by containing water, a pigment, and a resin emulsion as constituents of the ink, and also solves the problem of the bleeding of characters, which is a problem of the conventional dye ink, is reported. Have been. In some cases, a water-soluble resin is used. These pigment-dispersed inks have improved water resistance and light resistance by using pigments.

[0003]

However, in the conventional pigment ink, when water evaporates in the ink discharge nozzle, the viscosity of the pigment or polymer is increased due to aggregation of the pigment or polymer, and further, the film is formed into a film. There was a problem. An object of the present invention is to solve the above-mentioned problems of the prior art, and to provide an ink that can be stably ejected without causing clogging due to ink drying in an ink jet recording system, and without causing aggregation or precipitation for a long period of time. . Another object of the present invention is to provide an ink jet recording ink excellent in water resistance, light resistance and scratch resistance.

[0004]

Means for Solving the Problems As a result of intensive studies, the present inventors have achieved the above object by combining a polymer of flavonoid and / or indolequinone with an organic pigment, and have achieved the present invention. That is, the inkjet recording ink of the present invention is characterized by containing 0.1 to 10% of the flavonoid and / or indolequinone polymer and 0.5 to 20% of at least one organic pigment.

[0005]

DETAILED DESCRIPTION OF THE INVENTION Flavonoids used in the present invention

Embedded image It has a skeleton represented by For example

Embedded image Catechin (the structural formula shows a (+) form),

Embedded image Epicatechin (the structural formula shows a (-) form),

Embedded image Epigallocatechin (the structural formula shows a (-) form),

Embedded image Epicatechin gallate (the structural formula shows a (-) form),

Embedded image Catechin derivatives such as epigallocatechin gallate [the structural formula of which shows a (-) form] can be exemplified. These catechin derivatives also include fractions containing catechins extracted from natural products such as green tea. FIG. 1 shows an example of the green tea catechin extraction method.

The polymer of indolequinone used in the present invention is:

Embedded image Is a polymer having a skeleton represented by Melanins include natural melanin extracted from hair and the like in addition to those synthesized by oxidation. FIG. 2 shows an example of the hair melanin extraction method.

These exemplified flavonoid and indolequinone polymers are water-soluble, contain a large number of hydroxyl groups while having a condensed ring-like skeleton, and behave like a surfactant. Suitable for dispersion.
Even if a surfactant generally used at present has a low foaming property, the foaming property is low and causes clogging in a nozzle at the time of ejection. However, the weight of these exemplified flavonoids and indolequinone is high. The combined pigment dispersion has excellent foam breaking properties and has an effect of preventing nozzle clogging due to bubbles. Further, the surface tension of the pigment dispersion dispersed with the polymer of flavonoid and indolequinone has a characteristic of a high value of 50 to 70 dyne / cm, and is excellent in ejection stability.

As described above, the content of the flavonoid and / or indolequinone polymer in the ink is 0.1 to 10%. If the content is less than 0.1%, the effect of preventing clogging will not be sufficiently exhibited, and the dispersion stability will be reduced, resulting in poor storage stability. On the other hand, if the content is more than 10%, the viscosity of the ink increases, which causes a problem in ejection stability.

Any organic pigment can be used in the ink jet recording ink of the present invention. For example, C.I. I. Pigment Yellow 1,5,1
2,17,24,42,53,83,95,98,10
1,108,120,123,138 C.I. I. Pigment Red 1,3,4,5,1
2, 17, 23, 31, 48, 53, 58, 63, 6
4,81,87,88,171,175,185,18
7, 190, 208, 243 C.I. I. Pigment Blue 1,2,15,1
6, 27, 29, 56, 63 C.I. I. Pigment Black 1, 7, 11 and the like.

As described above, the content of the organic pigment in the ink is 0.5 to 20%. Content 0.5
%, The print and hue become unclear and 20%
If more, the viscosity of the ink increases.

In the ink jet recording ink of the present invention, one or both of a surfactant and a water-soluble resin can be used in combination as a dispersing aid for the organic pigment. Examples of the surfactant include higher fatty acid salts, alkyl sulfonates, lignin sulfonates, higher alcohol sulfates, sulfosuccinates, polyoxyethylene alkyl ethers, polyoxyethylene alkylphenol ethers, polyoxyethylene fatty acid esters, Polyoxyethylene sorbitan fatty acid ester,
There are acetylene glycol EO adducts and the like. Furthermore, a hydrophilic organic solvent and a nitrogen-containing compound can be added for the purpose of improving clogging resistance, moisture retention, dispersion stability and the like in the nozzle and the like. Examples of the hydrophilic organic solvent include ethylene glycol, glycerin, diethylene glycol, propylene glycol, ethylene glycol monoethyl ether, diethylene glycol monobutyl ether, monoethanolamine, diethanolamine,
There are triethanolamine, methylpyrrolidone, etc., which can be added to such an extent that no bleeding occurs. Also,
Examples of the nitrogen-containing compound include urea, thiourea, ethylene urea, alkyl urea, alkyl thiourea, dialkyl urea, and dialkyl thiourea. Examples of the water-soluble resin include polyvinylpyrrolidone, acrylic-modified resin, styrene-modified resin, polyvinyl alcohol, polyvinyl acetate, cellulose derivatives, proteins such as casein, and glycosides such as saponin.

The ink jet recording ink of the present invention comprises:
The components are prepared by mixing the above components, and can be prepared using a conventionally known device such as a ball mill, a sand mill, a roll mill, and an ultrasonic disperser.
In preparing the inkjet recording ink of the present invention, it is desirable to remove coarse particles. For example,
The mixed ink is subjected to a filtration treatment using a 1-micron filter with a pressure filter to remove particles of 1 μm or more, whereby an ink without clogging can be obtained.

[0013]

[Example 1] C.I. I. Pigment Black 7: 7 wt% (-) epicatechin [manufactured by Kurita Water Industries Ltd.]: 5 wt% POE benzyl ether: 3 wt% Glycerin: 6 wt% Water: 81 wt% 5 wt% of the above epicatechin, 3 wt% of POE benzyl ether After adding and dissolving 81 wt% of water to 6 wt% of glycerin and glycerin, C.I. I. PigmentBlack
7 was added in an amount of 7 wt% and dispersed by ultrasonic crushing or ball milling. The obtained dispersion was filtered through a 1-micron filter to prepare an ink composition.

Embodiment 2 C.I. I. Pigment Black 7: 10% by weight Hair extracted melanin: 7% by weight PEG # 200: 6% by weight Water: 77% by weight The above components were dispersed by the same production method as in Example 1. The obtained dispersion was filtered through a 1-micron filter to prepare an ink composition.

[Example 3] I. Pigment Red 122: 4% by weight Synthetic catechin (manufactured by Funakoshi Co., Ltd.): 10% by weight Glycerin: 5% by weight Water: 81% by weight The above components were dispersed by the same production method as in Example 1. The obtained dispersion was filtered through a 1-micron filter to prepare an ink composition.

Example 4 C.I. I. Pigment Red 209: 6 wt% (-) epigallocatechin gallate [produced by Kurita Water Industries Ltd.]: 4 wt% Styrene-acrylic acid copolymer: 1 wt% Diethylene glycol: 5 wt% Water: 84 wt% And dispersed by the same manufacturing method. The obtained dispersion was filtered through a 1-micron filter to prepare an ink composition.

Example 5 C.I. I. Pigment Yellow 108: 4% by weight Synthetic catechin (manufactured by Nacalai Tesque, Inc.): 2% by weight Acetylene glycol EO adduct: 1% by weight 2-methylpyrrolidone: 6% by weight Water: 87% by weight The above components were produced in the same manner as in Example 1. Dispersed by the way. The obtained dispersion was filtered through a 1-micron filter to prepare an ink composition.

Example 6 C.I. I. Pigment Yellow 24: 7% by weight Green tea extracted catechin [(+) catechin]: 3% by weight PEG # 200: 1% by weight Water: 89% by weight The above components were dispersed by the same production method as in Example 1. The obtained dispersion was filtered through a 1-micron filter to prepare an ink composition.

Example 7 C.I. I. Pigment Blue 15: 5 wt% (-) epicatechin gallate [produced by Kurita Water Industries Ltd.]: 1 wt% Polyvinylpyrrolidone: 3 wt% Propylene glycol: 4 wt% Water: 87 wt% The same components as in Example 1 were produced. Dispersed by the way. The obtained dispersion was filtered through a 1-micron filter to prepare an ink composition.

Example 8 C.I. I. Pigment Blue 16: 3% by weight (-) epigallocatechin (manufactured by Kurita Kogyo Co., Ltd.): 5% by weight Ethylene glycol: 7% by weight Water: 85% by weight The above-mentioned components were dispersed by the same manufacturing method as in Example 1. The obtained dispersion was filtered through a 1-micron filter to prepare an ink composition.

Comparative Example 1 C.I. I. Pigment Black 7: 10 wt% Styrene-maleic acid copolymer: 4 wt% Glycerin: 6 wt% Water: 80 wt% The above components were dispersed by the same production method as in Example 1. The obtained dispersion was filtered through a 5-micron filter to prepare an ink composition.

Comparative Example 2 C.I. I. Pigment Red 202: 5 wt% Styrene-acrylic acid copolymer: 10 wt% PEG # 200: 4 wt% Water: 81 wt% The above components were dispersed by the same production method as in Example 1. The obtained dispersion was filtered through a 5-micron filter to prepare an ink composition.

Storage stability test The ink compositions of Examples 1 to 8 and Comparative Examples 1 and 2 were allowed to stand in a thermostat at 60 ° C. for 6 months and then examined as follows.

1-1. Dispersion stability test Precipitates and liquid separation were visually confirmed. No liquid separation or sediment was observed. ◎, slight liquid separation was observed, but returned to the original state due to weak shaking. ○, slight precipitation was observed △, liquid separation and sedimentation was severe. A sample that did not return to its original state after shaking was evaluated as x, and is shown in Table 1.

1-2. Physical property change test The viscosity was measured before and after standing, and the change was observed.も の: no change in viscosity was observed, も の: increase in viscosity was within 10% of the initial value, 、: change in viscosity was 10 to 50% of the initial value, △: gel or hard precipitate was formed. Those were judged as ×, and the results are shown in Table 1.

Printer Printability Test The following examinations were performed using the ink compositions of Examples 1 to 8 and Comparative Examples 1 and 2 in a piezo-type inkjet printer.

2-1. Continuous Printing (Ink Discharge Stability) Test 100 continuous printings were performed using a piezo-type inkjet printer, and the printability was visually observed.も の: good printability with no bleeding, 生 じ る: slight bleeding and print disorder ○, 、: bleeding but character recognition possible, 、: bleeding and character recognition impossible Was determined to be ×, and the results are shown in Table 1.

2-2. Restart (ink clogging) test After printing with a piezo-type inkjet printer,
The printing was performed again by leaving the ink cap open at 40 ° C. for 2 hours, and clogging and the like were confirmed by comparing the printed matter.も の indicates that there is no clogging and has good printability, 抜 け indicates that slight omission is observable, 簡 単 indicates that there is clogging but can be printed by a simple recovery operation, and を indicates that printing is impossible. It was determined and shown in Table 1.

[Results]

[Table 1]

[0030]

As described above, the ink jet recording ink of the present invention has satisfactory rub resistance and water resistance of the printed matter, has high storage stability of the ink, and has good ink cohesion, precipitation, Since there is no deterioration or the like, the ejection stability is high in the ink jet printer, and clear printing can be realized without causing clogging of the ink ejection nozzle.

[Brief description of the drawings]

FIG. 1 is a flowchart showing an example of a green tea catechin extraction method.

FIG. 2 is a flowchart showing an example of a hair melanin extraction method.

Claims (3)

[Claims] 1. A polymer of 0.1 to 10% of a flavonoid and / or indolequinone and one or more organic pigments.
An ink for inkjet recording, comprising 5 to 20%. 2. The ink of claim 1, wherein the flavonoid is a catechin derivative. 3. The ink of claim 1, wherein the polymer of indolequinone is melanin.