JP2002053780A - Aqueous ink composition - Google Patents

Abstract

(57) [Problem] To provide an aqueous ink composition which has excellent ejection stability and does not have a possibility of causing nozzle clogging when used as an ink jet recording ink. SOLUTION: The aqueous ink composition of the present invention comprises at least an aqueous ink composition containing a coloring material and water,
Hydroxyisopropyldimethylamine, hydroxyisopropyldiisopropylamine, hydroxyisopropyldibutylamine, dihydroxyisopropylethylamine, dihydroxyisopropylisopropylamine, dihydroxyisopropylbutylamine, dihydroxyisopropylhydroxyethylamine and dihydroxyethylhydroxyisopropylamine, dihydroxyethyl-n-butylamine, hydroxyethyldiisopropylamine And one or more organic amine compounds selected from the group consisting of hydroxyethyl di-n-butylamine.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aqueous ink composition which has excellent ejection stability and does not cause clogging of nozzles when used as an ink jet recording ink.

[0002]

2. Description of the Related Art An ink jet recording system is a system in which ink droplets are ejected directly from a very fine nozzle onto a recording medium and adhered to obtain characters and images. There are many operation principles, such as a deflection method, a cavity method, a thermojet method, a bubble jet method, and a thermal inkjet method.
In any of the ink jet recording methods, ink droplets must be continuously and stably ejected from fine nozzles. For this reason, the ink jet recording ink has the same high image quality and robustness (water resistance and light resistance) of the recorded image as well as the ordinary ink, and also has high ejection stability and does not cause clogging of nozzles. Is required.

[0003] As an ink jet recording ink for improving the ejection stability, for example, JP-A-8-60053 discloses a dye ink containing an organic amine such as tripropanolamine. Kaihei 6-
JP-A-264016 discloses an ink jet recording ink containing two or more pigments, a polymer dispersant, a water-soluble organic solvent, a drying inhibitor, and two or more organic amines such as aminomethylpropanol. However, none of the inks has sufficient ejection stability for practical use.

Accordingly, an object of the present invention is to provide an aqueous ink composition which has excellent ejection stability and does not cause clogging of nozzles when used as an ink for ink jet recording.

[0005]

Means for Solving the Problems The present inventors have conducted various studies on an aqueous ink composition containing at least a coloring material and water and found that the above object can be achieved by including a specific organic amine compound. Was found.

[0006] The present invention has been made based on the above-mentioned findings, and it is intended that an aqueous ink composition containing at least a coloring material and water contains hydroxyisopropyldimethylamine,
Hydroxyisopropyl diisopropylamine, hydroxyisopropyl dibutylamine, dihydroxyisopropylethylamine, dihydroxyisopropylisopropylamine, dihydroxyisopropylbutylamine, dihydroxyisopropylhydroxyethylamine and dihydroxyethylhydroxyisopropylamine, dihydroxyethyl-n-butylamine, hydroxyethyldiisopropylamine and hydroxyethyldi- One or two selected from the group consisting of n-butylamine
The above object has been achieved by providing an aqueous ink composition containing at least one kind of organic amine compound.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the aqueous ink composition of the present invention will be described in detail. As described above, the aqueous ink composition of the present invention contains a coloring material, water and a specific organic amine compound. The coloring material is the same as that in this type of ink, and the main characteristics of the organic amine compound are as follows. It has.

The specific organic amine compound contained in the aqueous ink composition of the present invention includes one or more selected from the group consisting of the organic amine compounds.
Of these, especially hydroxyisopropyl diisopropylamine, hydroxyisopropyl dibutylamine,
It is preferable to use dihydroxyisopropylbutylamine since the ejection stability can be further improved.

The organic amine compound is contained in the aqueous ink composition of the present invention preferably in an amount of 0.01 to 5% by weight, more preferably 0.05 to 2% by weight. Content is 0.
If it is less than 01% by weight, there is no effect on the ejection stability. If it exceeds 5% by weight, it may be difficult to adjust the pH of the aqueous ink composition to a desired range (described later).

As the coloring material contained in the aqueous ink composition of the present invention, most of the coloring materials (dyes and pigments) described in the color index can be used. In addition, many materials that are not described in the color index can be suitably used.

The dye that can be used as the coloring material is not particularly limited, and can be selected from acid dyes, basic dyes, direct dyes, reactive dyes, and the like. Direct Yellow 12,
26, 86, 130, Basic Yellow 9, 11, Acid Red 27, 28, 52, 254, 289, Reactive Red 180, Direct Red 9, 13, 1
7, 23, 227, Basic Red 3, Acid Blue 9, 254, Basic Blue 9, Direct Blue 78, 86, 199, Acid Black 52, 172,
208, food black 2, direct black 19,
22, 28, 154, Process Reactive Black 3
1 etc. can be illustrated.

Examples of the pigment which can be used as the coloring material include, for example, pigments such as carbon black and pigment yellow, pigment red, pigment violet, pigment blue and pigment black described in Color Index, and phthalocyanine. And azo-based, anthraquinone-based, azomethine-based and condensed ring-based pigments. In addition, yellow No. 4, No. 5, No. 20
No. 5, No. 401; Orange No. 204; Red No. 104, 201
No. 202, 204, 220, 226-228
Organic pigments such as No. 405 and Blue No. 1 and 404, and inorganic pigments such as titanium oxide, zinc oxide, zirconium oxide, iron oxide, ultramarine, navy blue, and chromium oxide can also be used.

When a pigment is used as the colorant, it is preferable to use a dispersant together with the pigment or to use a surface-modified pigment as the pigment from the viewpoint of dispersion stability in the ink.

As the dispersant, additives such as a surfactant or a polymer material generally used for dispersing a pigment in an aqueous medium such as an ink can be used without any particular limitation. Specifically, for example, anionic surfactants such as higher fatty acid salts and higher alcohol sulfates, cationic surfactants such as aliphatic amine salts and phosphonium salts, and nonionic surfactants such as fatty acid esters of polyoxyethylene compounds Such as water-soluble surfactants, gelatin,
Proteins such as casein, natural gums such as gum arabic,
Glucoxides such as savonin, cellulose derivatives such as methylcellulose, carboxymethylcellulose, hydroxymethylcellulose, natural polymers such as ligninsulfonate and shellac, polyacrylates, styrene-acrylic acid copolymer salts, vinylnaphthalene-acrylic acid copolymers Salt, styrene-maleic acid copolymer salt, vinylnaphthalene-maleic acid copolymer salt, β-naphthalenesulfonic acid formalin condensate salt, anionic polymer such as polyphosphoric acid, polyvinyl alcohol, polyvinylpyrrolidone, polyethylene Nonionic polymers such as glycol can be exemplified, and one or more of these may be used.

The dispersant has a weight average molecular weight of 100 to 5000 from the viewpoint of solubility in the aqueous ink composition.
It is preferably in the range of 0, and more preferably in the range of 200 to 40,000. When the molecular weight is less than 100, the printing unevenness is remarkable, and when it exceeds 50,000, the ink viscosity is remarkably increased, and there is a possibility that the ink cannot be used as an ink for ink jet recording. Solid printing may not be possible.

The dispersant is contained in the aqueous ink composition of the present invention preferably in an amount of 0.01 to 5% by weight, more preferably 0.3 to 2% by weight. Content is 0.01% by weight
If the amount is less than 5%, there is no effect on the dispersion stability of the pigment.

Further, the surface-modified pigment which can be used as the coloring material has "a large number of hydrophilic functional groups and / or salts thereof" (hereinafter referred to as dispersibility-imparting groups) on the surface of the pigment.
Are bonded directly or indirectly via an alkyl group, an alkyl ether group, an aryl group, or the like, and can be dispersed and / or dissolved in an aqueous medium without a dispersant. “Dispersing and / or dissolving in an aqueous medium without a dispersant” means that the dispersoid (pigment) is stably present at a minimum particle size that can be dispersed in the aqueous medium without using a dispersant as described above. State. Here, the “minimum particle size that can be dispersed” refers to the minimum particle size of the dispersoid that does not become smaller even if the dispersion time is increased.

The ink containing the surface-modified pigment is as follows:
It is not necessary to contain a dispersant as in a normal water-based pigment ink, and therefore, as seen in a normal water-based pigment ink,
There is almost no foaming due to a decrease in the defoaming property due to the dispersant, and the ejection stability is excellent. In addition, since the ink containing the surface-modified pigment has an appropriate viscosity, the ink can contain more pigment, and the printing density can be sufficiently increased. It is.

The hydrophilic functional group bonded to the surface of the surface-modified pigment is selected from the group consisting of a carboxyl group, a carbonyl group, a hydroxyl group, a sulfone group, a phosphoric acid group and a quaternary ammonium salt. Species or two or more species. As the pigment used as a raw material of the surface-modified pigment, the same pigment as that used as the coloring material is used.

The surface-modified pigment is prepared by subjecting the pigment to a physical treatment or a chemical treatment to bond (graft) the dispersibility-imparting group or the active species having the dispersibility-imparting group to the surface of the pigment. ). Examples of the physical processing include a vacuum plasma processing and the like. Further, as the chemical treatment, for example,
A method of oxidizing the pigment surface with an oxidizing agent in water to directly bond a carboxyl group or a sulfone group to the pigment surface,
A method in which p-amino-benzoic acid is bonded to the pigment surface to bond a carboxyl group via a phenyl group is exemplified.

The pigment (including the surface-modified pigment) is
From the viewpoint of storage stability of the ink and prevention of nozzle clogging, the average particle diameter is preferably from 1 to 300 nm, more preferably from 10 to 200 nm.

The coloring material is preferably 1 to 30% by weight, more preferably 3 to 1% by weight in the aqueous ink composition of the present invention.
0% by weight is contained. When the content is less than 1% by weight, the print density is insufficient, and when the content is more than 30% by weight, the viscosity may increase or nozzles may be clogged when used as ink for inkjet recording.

The water contained in the aqueous ink composition of the present invention is a main solvent, and pure water such as ion-exchanged water, ultrafiltration water, reverse osmosis water, distilled water or ultrapure water can be used.
In particular, it is preferable to use water that has been sterilized by ultraviolet irradiation, addition of hydrogen peroxide, or the like, in order to prevent generation of mold and bacteria and to enable long-term storage of the ink.

Water is preferably 30 to 90% by weight, more preferably 40 to 80% by weight in the aqueous ink composition of the present invention.
% By weight.

The aqueous ink composition of the present invention contains the above-mentioned components (colorant, specific organic amine compound and water) to enhance the ejection stability. Various components as described in (1) can be contained.

The aqueous ink composition of the present invention may further contain a penetration enhancer from the viewpoint of enhancing the permeability to the recording medium. As the penetration enhancer, one that can lower the surface tension of an aqueous solution (aqueous ink composition) and increase the permeability (wetting property) of the aqueous solution to a recording medium is used. Solvents and / or surfactants are used.

Examples of the water-soluble organic solvent include lower alcohols such as ethanol and propanol, cellosolves such as ethylene glycol monomethyl ether and ethylene glycol monoethyl ether, and carbitols such as diethylene glycol monomethyl ether and diethylene glycol monoethyl ether. And ethylene glycol mono-n-butyl ether, diethylene glycol-n-butyl ether, triethylene glycol-n
And glycol ethers such as -butyl ether, and one or more of these are used. Among these, glycol ethers are particularly preferable in that a high quality recorded matter with almost no ink bleeding can be provided.

Further, as the surfactant, for example,
Examples include anionic surfactants such as fatty acid salts and alkyl sulfate salts, nonionic surfactants such as polyoxyethylene alkyl ether and polyoxyethylene alkyl phenyl ether, cationic surfactants and amphoteric surfactants. And one or more of these are used. Among them, it is particularly preferable to use a nonionic surfactant from the viewpoint of suppressing the generation (foaming) of bubbles in the ink.

Preferred specific examples of the nonionic surfactant include, for example, Nissan Nonion K-211 and K
-220, P-213, E-215, E-220, S-
215, S-220, HS-220, NS-212, N
S-220 (all trade names, manufactured by NOF Corporation) and the like, and one or more of these are used. In particular, Surfynol 61, 82, 104, 440, 465,
It is preferable to use an acetylene glycol-based surfactant such as 485 (all trade names, manufactured by Air Products and Chemicals). An ink containing an acetylene glycol-based surfactant has almost no foaming and is particularly excellent in ejection stability, and is suitable for an ink jet recording method.

The penetration enhancer is contained in the aqueous ink composition of the present invention preferably in an amount of 0.001 to 5% by weight, more preferably 0.005 to 2% by weight. Content 0.0
If it is less than 01% by weight, there is no effect in promoting ink permeability, and if it is more than 5% by weight, the ejection stability of the aqueous ink composition may be reduced.

The aqueous ink composition of the present invention may contain a humectant from the viewpoint of further improving the ejection stability. As the humectant, for example, glycerin, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, 1,3-
Propanediol, 1,4-butanediol, 1,5-
Pentanediol 1,6-hexanediol, 1,2,2
Polyols such as 6-hexanetriol and pentaerythritol, lactams such as 2-pyrrolidone, N-methyl-2-pyrrolidone and ε-caprolactam, urea, thiourea, ethylene urea, 1,3-dimethylimidazolidinone and the like And saccharides such as maltitol, sorbitol, gluconolactone, and maltose, and one or more of these are used.

The humectant is preferably 1 to 30% by weight, more preferably 5 to 2% by weight in the aqueous ink composition of the present invention.
0% by weight is contained.

From the same viewpoint, the aqueous ink composition of the present invention may contain a fungicide and a preservative. Examples of the fungicides and preservatives include sodium benzoate, sodium pentachlorophenol, sodium 2-pyridinethiol-1-oxide, sodium sorbate, sodium dehydroacetate, and 1,2-dibenzisothiazolin-3-one. (Proxel CRL, Proxel BDN, Proxel GXL, Proxel XL-2, Proxel TN, manufactured by AVECIA), and one or more of these can be used.

The antifungal agent / preservative is preferably contained in the aqueous ink composition of the present invention in an amount of 0.001 to 3% by weight, more preferably 0.01 to 1% by weight.

The aqueous ink composition of the present invention can further contain, if necessary, additives such as a viscosity modifier, an antioxidant, an ultraviolet absorber, a chelating agent, and an oxygen absorber. One or more kinds are used.

From the viewpoint of ejection stability, the aqueous ink composition of the present invention has a viscosity at 25 ° C. of 1 to 25 mPa.
S, more preferably 1 to 15 mPa · s. The viscosity is JIS Z8803-1
Measured according to 991. The viscosity is adjusted in the aqueous ink composition by using a viscosity modifier such as rosins, alginic acids, polyvinyl alcohol, hydroxypropyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, methyl cellulose, polyacrylate, polyvinyl pyrrolidone, and gum arabic starch. Can be carried out.

The aqueous ink composition of the present invention has a permeation time of 1 second when the coating amount on a recording medium is 1 mg / cm ² , from the viewpoint of providing a good recorded matter with little bleeding. It is preferred to have a permeability that is less than. Here, the penetrability such that “the permeation time when the amount of application to the recording medium is 1 mg / cm ² is less than 1 second” means that the recording medium is coated with 50 ng of the aqueous ink composition at an application area of 360 dpi (dots). / Inch) × 360 dpi. Immediately after application at 360 dpi, the permeability of the aqueous ink composition is less than 1 second until the applied surface is not stained with the aqueous ink composition even when the applied surface is touched. . At this time, neutral plain paper (for example, trade name “Xerox-P”, manufactured by Fuji Xerox Co., Ltd.) is used as a recording medium. Such permeability can be imparted by incorporating the above-mentioned predetermined amount of the penetration enhancer into the aqueous ink composition.

From the same viewpoint, the aqueous ink composition of the present invention preferably has a surface tension of less than 40 mN / m, more preferably 35 mN / m. The surface tension is measured according to JIS K3362-1978. The adjustment of the surface tension can be performed by including the above-mentioned predetermined amount of the penetration enhancer in the aqueous ink composition.

The aqueous ink composition of the present invention has a pH of 6 to 1 from the viewpoint of improving the print density and the stability of the liquid.
It is preferably 0, more preferably 7 to 9.5. Adjustment of the pH can be performed by including the above-mentioned predetermined amount of the specific organic amine compound which is an alkali agent in the aqueous ink composition.

The aqueous ink composition of the present invention can be prepared using a conventionally known apparatus, for example, a ball mill, a sand mill, an attritor, a basket mill, a roll mill, or the like, in the same manner as a conventional ink. At the time of preparation, it is preferable to remove coarse particles from the viewpoint of preventing nozzle clogging. The coarse particles can be removed by, for example, filtering the ink obtained by mixing the above components using a filter such as a membrane filter or a mesh filter, and preferably removing particles of 10 μm or more, more preferably 5 μm or more. This is done by:

The aqueous ink composition of the present invention can be suitably used in any recording method in which printing is performed by attaching the aqueous ink composition to a recording medium. Examples of such a recording method include, for example, an ink jet recording method which is a recording method in which droplets of an aqueous ink composition are ejected and the droplets are attached to a recording medium to perform printing, a recording method using a writing instrument such as a pen, Other various printing methods can be mentioned, and it is particularly preferable to use it for an ink jet recording method, especially for an on-demand type ink jet recording method.
Examples of the on-demand type ink jet recording method include, for example, a piezoelectric element recording method for performing recording using a piezoelectric element disposed on a printer head, and using heat energy from a heater of a heating resistor element disposed on the printer head. And a thermal jet recording method in which recording is performed by any of the methods described above.

The aqueous ink composition of the present invention has excellent ejection stability due to the action of the specific organic amine compound, and does not cause clogging of nozzles when used as an ink for inkjet recording. Further, the aqueous ink composition of the present invention using the surface-modified pigment as the coloring material does not need to contain a dispersant for dispersing the pigment, and therefore has very little foaming and is extremely excellent in ejection stability.
Furthermore, the pigment content can be increased to a level having an appropriate viscosity and a sufficient print density, and the handling is easier than that of a conventional pigment ink containing a dispersant. Further, since the aqueous ink composition of the present invention containing the penetration enhancer has a high permeability to a recording medium, a dry time is short, and it is possible to provide a recorded matter of good quality with almost no ink bleeding. Yes, there is no risk of bleeding even when used for multi-color printing. Furthermore, not only for recording media with high ink absorption such as paper, but also for recording media with low ink absorption such as OHP sheets Even so, characters and / or images can be formed, and the applicable recording medium is wide.

[0043]

EXAMPLES Examples of the aqueous ink composition of the present invention are shown below. However, it goes without saying that the present invention is not limited to such an embodiment.

Examples 1 to 22 and Comparative Examples 1 to 6 Aqueous ink compositions having the compositions shown in Tables 1 to 4 below were prepared. For the preparation, each component was mixed at 25 ° C. and stirred for 2 hours, and then 2 k using a 5 μm diameter membrane filter.
The filtration was performed under pressure at a pressure of g / cm ² .
In Examples 1 to 22, the compound No. shown in the following [Chemical Formula 1] was used as the alkaline agent. Nos. 1 to 11 were used (all of which were the specific organic amine compounds). In Comparative Examples 1 and 4, KOH was used, and in Comparative Examples 2, 3, 5, and 6, the compound No. 1 shown in the following Chemical Formula 1 was used. 12 and 13 were used (both compounds outside the scope of the present invention). Each of the pigment dispersions used in Examples 3, 7, 11, 15, 18, and 21 and Comparative Examples 3 and 5 is a type of pigment dispersion in which a pigment is stably dispersed in an aqueous medium using a dispersant. Liquid. Examples 4, 8, 12, 16, 19 and 22
Further, the pigment dispersion used in Comparative Example 6 is a surface-modified pigment dispersion in which a pigment is stably dispersed in an aqueous medium without using any dispersant. However, the addition amounts of the coloring materials (dyes and pigments) of Examples 1 to 22 and Comparative Examples 1 to 6 shown in Tables 1 to 4 below are calculated in terms of the coloring material solids.

[0045]

[Table 1]

[0046]

[Table 2]

[0047]

[Table 3]

[0048]

[Table 4]

[0049]

Embedded image

[Evaluation of Clogging Resistance] Each of the aqueous ink compositions of Examples 1 to 22 and Comparative Examples 1 to 6 was evaluated by the following <Evaluation method of clogging resistance>. The results are shown in Table 5 below.

<Evaluation Method of Clogging Resistance> The aqueous ink composition was filled in a piezoelectric element type ink jet recording apparatus (trade name “MJ-930C”, manufactured by Seiko Epson Corporation), and printing was performed. It was confirmed that the ink composition was discharged stably. Thereafter, the ink jet recording apparatus was left for 4 weeks in an environment at a temperature of 50 ° C. and a relative humidity of 40% with the print head part removed from the home position. After the standing, the inkjet recording apparatus was moved to an environment at normal temperature, and after waiting for the temperature to drop to normal temperature, the main body power was turned on, printing was performed again, and the ejection state of the aqueous ink composition was visually observed. At this time, if the ejection is not stable, the cleaning operation of the predetermined head unit of the inkjet recording apparatus is performed, and the head unit required until the aqueous ink composition is stably ejected (returns). The number of cleaning operations was evaluated and evaluated according to the following evaluation criteria. <Evaluation Criteria> A: Ejection after standing is extremely stable, and no cleaning operation of the head is required. B: Discharge after standing was unstable, and 2
Up to cleaning operations are required. C: The ejection after standing was unstable, and the head portion 3
Up to five cleaning operations are required. NG: The ejection after standing was unstable, and the head section was not restored even after cleaning was performed six times or more.

[0052]

[Table 5]

As is clear from the results shown in Table 5, the aqueous ink compositions of Examples 1 to 22 containing the specific organic amine compound all showed excellent clogging resistance. In contrast, the aqueous ink compositions of Comparative Examples 1 to 6
None of them contained the organic amine compound, resulting in poor clogging resistance. Further, the aqueous ink compositions of Examples 5 to 16 and 20 to 22 containing the penetration enhancer all gave good quality recorded matter with little bleeding.
Further, the aqueous ink compositions of Examples 13 to 16 and 20 to 22 containing Surfynol 465, which is an acetylene glycol-based surfactant, as a nonionic surfactant, had very little foaming and were easy to handle. .

[0054]

According to the aqueous ink composition of the present invention, the ejection stability is excellent, and when used as an ink for ink jet recording, there is no possibility that nozzle clogging will occur.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2C056 EA14 FA02 FC02 2H086 BA52 BA53 BA55 BA59 BA60 BA62 4J039 AB01 AB02 AB07 AB08 AD06 AD23 BA04 BC35 BE01 BE02 BE03 BE04 BE05 BE33 CA03 CA06 EA41 EA44 EA48 GA24

Claims (8)

[Claims] 1. An aqueous ink composition containing at least a coloring material and water, comprising: hydroxyisopropyldimethylamine, hydroxyisopropyldiisopropylamine, hydroxyisopropyldibutylamine, dihydroxyisopropylethylamine, dihydroxyisopropylisopropylamine, dihydroxyisopropylbutylamine, dihydroxyisopropyl Aqueous ink composition containing one or more organic amine compounds selected from the group consisting of hydroxyethylamine, dihydroxyethylhydroxyisopropylamine, dihydroxyethyl-n-butylamine, hydroxyethyldiisopropylamine and hydroxyethyldi-n-butylamine object. 2. The aqueous ink composition according to claim 1, comprising 0.01 to 5% by weight of the organic amine compound. 3. A composition having a viscosity at 25 ° C. of 1 to 25 mPa ·
3. The aqueous ink composition according to claim 1, which is s. 4. The aqueous ink composition according to claim 1, which is used in an ink jet recording method. 5. The aqueous ink composition according to claim 4, wherein the ink jet recording method is an on-demand type ink jet recording method. 6. A recording method for printing by attaching the aqueous ink composition according to claim 1 to a recording medium. 7. An ink jet recording method comprising discharging droplets of the aqueous ink composition according to claim 1 and attaching the droplets to a recording medium to perform printing. 8. A recorded matter recorded by the recording method according to claim 6. Description: