JP2002053783A - Water base ink composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water base ink composition which has excellent jetting stability and, at the same time, can provide prints of good quality with least bleeding of an ink. SOLUTION: The water base ink composition comprises at least a pigment, a dispersing agent, an organic amine compound having a propanol skeleton, a penetration accelerator, and water.

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. In recent years, printers used as output devices for personal computers and the like are becoming multicolored. However, according to this recording method, multicolor printing can be easily performed, and thus this recording method has rapidly spread in various applications. There are many operation principles, such as a deflection method, a cavity method, a thermojet method, a bubble jet method, and a thermal ink jet method.In any of the ink jet recording methods, ink droplets are continuously and stably supplied from fine nozzles. Must be dispensed. For this reason, the ink for inkjet recording is required to have high ejection stability in addition to high image quality and robustness (water resistance and light resistance) of a recorded image and to prevent nozzle clogging.

[0003] Ink-jet recording inks are often water-based inks from the viewpoints of handleability and safety. Aqueous inks can be broadly divided into dye inks and pigment inks. For dye inks, for example,
JP-A-8-60053 discloses a dye ink containing an organic amine as an ink having excellent ejection stability. On the other hand, pigment inks are more excellent in image fastness than dye inks, and the development of ink jet recording inks that take advantage of the properties is desired, but the ejection stability is inferior to dye inks, There is a disadvantage that nozzle clogging due to sedimentation / agglomeration of the pigment easily occurs.
For this reason, improving the ejection stability of the pigment ink is a technical problem that must be solved by all means.

As an attempt to improve the ejection stability of pigment ink, for example, JP-A-6-264016 discloses a pigment, a polymer dispersant, a water-soluble organic solvent, a drying inhibitor and an organic amine. An ink jet recording ink containing the above is disclosed. However, although this ink contains aminomethylpropanol, which is an organic amine compound having a propanol skeleton capable of imparting excellent ejection stability, it is an ink of a so-called slow penetration type having high surface tension and being hardly wetted by paper. Therefore, there is a problem that the drying time is long. In addition, when this ink is used for multicolor printing, ink droplets on a recording medium are connected to each other at boundaries of different colors, and there is a possibility that image quality may be deteriorated due to mixing of colors called bleed. It was not a suitable ink. Also, this ink is OH
It cannot be applied to printing on a non-absorbing recording medium such as a P sheet, and the applicable width of the recording medium is narrow.

Accordingly, it is an object of the present invention to provide excellent ejection stability, no risk of clogging of nozzles when used as an ink jet recording ink, short drying time, less bleeding, and application of the present invention. An object of the present invention is to provide an aqueous ink composition having a wide range of possible recording media.

[0006]

DISCLOSURE OF THE INVENTION The present invention has been made as a result of various studies to achieve the above object, and contains at least a pigment, a dispersant, an organic amine compound having a propanol skeleton, a penetration enhancer, and water. The present invention provides a water-based ink composition.

[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 pigment, a dispersant, an “organic amine compound having a propanol skeleton” (hereinafter, referred to as an organic amine), a penetration enhancer, and water as essential components.

The pigments contained in the aqueous ink composition of the present invention include, for example, carbon black and pigments such as Pigment Yellow, Pigment Red, Pigment Violet, Pigment Blue and Pigment Black described in Color Index. And phthalocyanine, azo, anthraquinone, azomethine, and condensed ring pigments. Also, Yellow No. 4,
No. 5, No. 205, No. 401; Orange No. 204; Red No. 104
No. 201, 202, 204, 220, 226
No. 228, 405; organic pigments such as Blue No. 1 and 404, and inorganic pigments such as titanium oxide, zinc oxide, zirconium oxide, iron oxide, ultramarine blue, navy blue, and chromium oxide.

The pigment has an average particle size of 1 to 3 from the viewpoints of storage stability of the ink and prevention of nozzle clogging.
It is preferably 300 nm, more preferably 10 to 200 nm.

[0010] The pigment 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.

As the dispersant contained in the aqueous ink composition of the present invention, the same dispersants as those in this type of aqueous pigment ink can be used without any particular limitation. Specifically, for example, higher fatty acid salts, anionic surfactants such as higher alcohol sulfates, aliphatic amine salts,
Cationic surfactants such as phosphonium salts, water-soluble surfactants such as nonionic surfactants such as fatty acid esters of polyoxyethylene compounds, gelatin, proteins such as casein, natural gums such as gum arabic, glucoxides such as savonin, Methylcellulose, carboxymethylcellulose, cellulose derivatives such as hydroxymethylcellulose, natural polymers such as ligninsulfonate and shellac, polyacrylates, styrene-acrylic acid copolymer salts, vinylnaphthalene-acrylic acid copolymer salts, styrene- Maleic acid copolymer salts, vinyl naphthalene-maleic acid copolymer salts, β-naphthalene sulfonic acid formalin condensate salts, anionic polymers such as polyphosphoric acid, polyvinyl alcohol, polyvinyl pyrrolidone, polyethylene glycol, etc. Nonio Can be exemplified sexual polymers such, these one or more is used.

The dispersant has a weight average molecular weight of 100 to 5,000 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.

The organic amine contained in the aqueous ink composition of the present invention is a compound represented by any of the following formulas (A) to (D).

[0015]

Embedded image (Wherein, R ₁ and R ₂ each independently represent a hydrogen atom or an optionally branched alkyl or hydroxyalkyl chain having 1 to 8 carbon atoms. R ₃ represents a hydrogen atom or a methyl group Represents.)

In the general formulas (A) to (D), R ₁
And R ₂ each independently represent a hydrogen atom or an optionally branched alkyl chain or hydroxyalkyl chain having 1 to 8 carbon atoms. Examples of the “optionally branched alkyl chain having 1 to 8 carbon atoms” include a methyl group,
Ethyl group, isopropyl group, tert-butyl group, 2-
Examples include a methylheptyl group and an n-octyl group. Examples of the “optionally branched hydroxyalkyl chain having 1 to 8 carbon atoms” include, for example, a hydroxymethyl group, a hydroxyethyl group, a hydroxyisopropyl group,
And a hydroxy-tert-butyl group. R ₁
And R ₂ is particularly preferably a hydroxyethyl group, a hydroxyisopropyl group, or a hydroxy-tert-butyl group. R ₃ in the general formula (B) represents a hydrogen atom or a methyl group, and a methyl group is particularly preferable.

Examples of the organic amine include aminomethylpropanol, tripropanolamine, N- (2
-Hydroxypropyl) triethylenetetramine, (2-hydroxypropyl) dimethylamine, N, N-bis (2-hydroxypropyl) -tert-butylamine, hydroxyisopropyltriethyleneamine, hydroxyisopropyldiisopropylamine, hydroxyisopropyldibutylamine, dihydroxy Isopropylethylamine, dihydroxyisopropyl-n-butylamine, dihydroxyisopropyl-tert-butylamine, N, N
-Bis (2-hydroxypropyl) -N-hydroxyethylamine and N-2-hydroxypropyl-N, N-bis (hydroxyethyl) amine, etc., and one or more of these are used. Especially tripropanolamine,
It is preferable to use aminomethylpropanol, N, N-bis (2-hydroxypropyl) -tert-butylamine and the like.

The organic amine 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. If the content is less than 0.01% by weight, there is no effect on the ejection stability.
Adjustment may be difficult.

The penetration enhancer contained in the aqueous ink composition of the present invention reduces the surface tension of an aqueous solution (aqueous ink composition) to increase the permeability (wettability) of the aqueous solution to a recording medium. What can be raised is used, and specifically, a water-soluble organic solvent and / or a surfactant 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 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 water contained in the aqueous ink composition of the present invention is a main solvent, and pure water such as ion exchange 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 contained in the aqueous ink composition of the present invention preferably at 30 to 90% by weight, more preferably at 40 to 80% by weight.

The aqueous ink composition of the present invention contains the above-mentioned components (pigment, dispersant, organic amine, penetration enhancer and water) to enhance the ejection stability and the permeability to the recording medium. However, if necessary, various components described below can be contained.

The aqueous ink composition of the present invention may contain a humectant from the viewpoint of further improving the ejection stability. Examples of humectants include glycerin, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, 1,3-propanediol, 1,4-butanediol, , 5-pentanediol 1,6-hexanediol, 1,2,6-hexanetriol, polyols such as pentaerythritol, 2-pyrrolidone, N-methyl-2-pyrrolidone, ε
Lactams such as caprolactam, ureas such as urea, thiourea, ethylene urea, 1,3-dimethylimidazolidinone, and saccharides such as maltitol, sorbitol, gluconolactone, and maltose; Species or two or more species are used.

The humectant is preferably present in the aqueous ink composition of the present invention in an amount of 1 to 30% by weight, more preferably 5 to 2% by weight.
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 may further contain additives such as a viscosity modifier, an antioxidant, an ultraviolet absorber, an antifoaming agent, a chelating agent and an oxygen absorber, if necessary. One or more of these can be used.

The aqueous ink composition of the present invention has a permeation time of 1 mg / cm ² when applied to a recording medium from the viewpoint of providing good recorded matter with little bleeding.
Preferably, it has a permeability such that it is less than a second. Here, the penetrability such that “permeation time when the amount of application to the recording medium is 1 mg / cm ² is less than 1 second” means that 50 ng of the aqueous ink composition is applied to the recording medium over an area of 360
Immediately after coating at dpi (dot / inch) × 360 dpi, the penetration of the water-based ink composition such that the time required for the water-based ink composition to clean the coated surface even after touching the coated surface is less than 1 second. Refers to sex. At this time, as a recording medium, neutral plain paper (for example, trade name “Xerox-
P ", manufactured by Fuji Xerox Co., Ltd.). 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, and 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 viscosity at 25 ° C. of 1 to 25 from the viewpoint of ejection stability.
mPa · s, preferably 1 to 15 mPa · s
Is more preferable. Viscosity is JIS Z880
Measured according to 3-1991. 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 pH of from 6 to 1 from the viewpoints of improving the printing density and liquid stability.
It is preferably 0, more preferably 7 to 9.5. The pH can be adjusted by adding the organic amine, which is an alkaline agent, to the aqueous ink composition in the predetermined amount.

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 organic amine, and does not cause clogging of nozzles when used as an ink for inkjet recording. Further, the aqueous ink composition of the present invention has a high permeability to a recording medium due to the action of the penetration enhancer, so that it is possible to provide a good quality recorded matter having a short drying time and almost no ink bleeding. There is no danger of bleeding even when used for multicolor printing. Further, characters and / or images can be formed not only on an absorbent recording medium such as paper but also on a non-absorbing recording medium such as an OHP sheet.

[0039]

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 6 and Comparative Examples 1 to 3 Aqueous ink compositions having the compositions shown in Table 1 below were prepared.
For the preparation, each component was mixed at 25 ° C. and stirred for 2 hours, and then, using a 5 μm diameter membrane filter, 2 kg /
This was performed by pressure filtration at a pressure of cm ² . In Examples 1 to 6, the compound No. shown in the following [Chemical Formula 3] was used as the alkaline agent. 1 to 6 were used (all were the above-mentioned organic amines). In Comparative Example 1, KOH was used. In Comparative Examples 2 and 3, the compound No. 7 and 8
Were used (all compounds outside the scope of the present invention).
Each of the pigment dispersions used in Examples 1 to 6 and Comparative Examples 1 to 3 is a pigment dispersion in which a pigment is stably dispersed in an aqueous medium using a dispersant. However, the added amount of the pigment dispersion in Table 1 below is calculated in terms of the solid content of the pigment.

[0041]

[Table 1]

[0042]

Embedded image

[Evaluation of Clogging Resistance] Each of the aqueous ink compositions of Examples 1 to 6 and Comparative Examples 1 to 3 was evaluated by the following <Evaluation method of clogging resistance>. The results are shown in Table 2 below.

<Evaluation Method of Clogging Resistance> The aqueous ink composition was filled into 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.

[0045]

[Table 2]

As is clear from the results shown in Table 2, the aqueous ink compositions of Examples 1 to 6 containing the organic amine all showed excellent clogging resistance. In contrast,
All of the aqueous ink compositions of Comparative Examples 1 to 3 did not contain the organic amine and resulted in poor clogging resistance. Further, the aqueous ink compositions of Examples 1 to 6 containing a penetration enhancer all gave good quality recorded matter with little bleeding. Further, Surfynol 46, which is an acetylene glycol-based surfactant, is used as a nonionic surfactant.
The aqueous ink compositions of Examples 5 and 6 containing No. 5 showed extremely little foaming and were easy to handle.

[0047]

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. Further, the aqueous ink composition of the present invention has a short drying time, can provide a good quality recorded matter with almost no ink bleeding, does not cause bleed even when used for multicolor printing, Wide width of applicable recording medium.

Claims (14)

[Claims] An aqueous ink composition comprising at least a pigment, a dispersant, an organic amine compound having a propanol skeleton, a penetration enhancer, and water. 2. The aqueous ink composition according to claim 1, wherein the organic amine compound having a propanol skeleton is a compound represented by any one of the following general formulas (A) to (D). Embedded image (Wherein, R ₁ and R ₂ each independently represent a hydrogen atom or an optionally branched alkyl or hydroxyalkyl chain having 1 to 8 carbon atoms. R ₃ represents a hydrogen atom or a methyl group Represents.) 3. The pigment of 1 to 30% by weight, the dispersant of 0.01 to 5% by weight, the organic amine compound having a propanol skeleton of 0.01 to 5% by weight and the penetration enhancer of 0.1 to 5% by weight. The aqueous ink composition according to claim 1, which contains 001 to 5% by weight. 4. The aqueous ink composition according to claim 1, wherein the penetration enhancer is a water-soluble organic solvent and / or a surfactant. 5. The aqueous ink composition according to claim 4, wherein the water-soluble organic solvent is a glycol ether. 6. The aqueous ink composition according to claim 4, wherein the surfactant is a nonionic surfactant. 7. The aqueous ink composition according to claim 6, wherein the nonionic surfactant is an acetylene glycol-based surfactant. 8. The recording medium according to claim 1, wherein the recording medium is neutral plain paper, and the penetration time is less than 1 second when the amount of application to the recording medium is 1 mg / cm ² . Aqueous ink composition. 9. The aqueous ink composition according to claim 1, which has a surface tension of less than 40 mN / m. 10. The aqueous ink composition according to claim 1, which is used in an ink jet recording method. 11. The aqueous ink composition according to claim 10, wherein the ink jet recording method is an on-demand type ink jet recording method. 12. A recording method for printing by attaching the aqueous ink composition according to claim 1 to a recording medium. 13. An ink jet recording method for discharging a droplet of the aqueous ink composition according to claim 1 and attaching the droplet to a recording medium to perform printing. 14. A recorded matter recorded by the recording method according to claim 12.