JPH11256083A - Water-base ink - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce an ink jet recording ink which is excellent in setting density, ink delivery rate, clogging prevention, etc., by distilling a water-soluble org. solvent out of a water/water-soluble org. solvent mixture soln. contg. a neutralization product of a polyester having a specified acid value, a water- insoluble colorant, and a specific water-soluble substance. SOLUTION: This ink is a water-base dispersion contg., as the dispersoid, a polyester with a water-insoluble colorant adsorbed thereby and is prepd. by distilling a water-soluble org. solvent out of a water/water-soluble org. solvent mixture soln. contg. a neutralization product of a polyester having an acid value of 1-100 mgKOH/g, a water-insoluble colorant, and at least one compd. selected from among water-soluble polyhydroxy compds., substantially water-soluble compds. represented by formulas I to III, and amino acids (salts). In the formulas, R<1> to R<4> are each H, a 1-5C alkyl, or (aminated) 2-6C acyl provided R<1> and R<2> are not simultaneously H; R is a 1-5C alkylene; and M is H or an alkali or alkaline earth metal.

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 for ink-jet recording useful for an ink-jet recording method.

[0002]

2. Description of the Related Art Water-based inks for ink-jet recording include:
In addition to high water resistance and high liquid stability, print density and ink ejection rate are high, and many properties such as excellent clogging prevention properties are required, but these properties also have a trade off. It is not easy to obtain an ink satisfying all these characteristics. In addition to the above requirements, the ink used in the ink jet recording method using thermal energy for ejecting the ink droplets is also required to have a characteristic that the heater is less scorched after continuous printing from the viewpoint of stable ejection. . The present inventors have proposed an aqueous ink comprising an aqueous dispersion containing a polyester to which a dye or a pigment is adsorbed as a dispersoid in order to achieve such an object (Japanese Patent Application Laid-Open No. 9-18 / 1997).
No. 3932), with the rapid evolution of inkjet printers, further improvements are desired.

[0003]

SUMMARY OF THE INVENTION The present invention is excellent in print density, ink ejection rate, anti-clogging property, non-sticking property of a heater mounted on an ink jet printer, less stain on a printer head, and high liquid stability. It is an object of the present invention to provide a water-based ink for ink-jet recording, which is excellent in drying resistance and obtained.

[0004]

That is, the gist of the present invention is as follows.
In an aqueous ink jet recording ink comprising an aqueous dispersion containing a polyester to which a water-insoluble coloring material is adsorbed as a dispersoid, the aqueous dispersion comprises the following a), b) and c)
A water-based ink for ink-jet recording, characterized by being obtained by distilling off the water-soluble organic solvent from a water-water-soluble organic solvent mixed solution containing: a) an acid value of 1 to 100 mgKOH / g; Neutralized polyester,
b) a water-insoluble colorant; c) one or more compounds selected from the group consisting of c1) and c2); c1) a water-soluble polyhydroxy compound having a boiling point higher than that of water; c2) a general formula (1); Formula (2) and general formula (3):

[0005]

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Wherein R ^{1 to} R ⁴ are the same or different and are each a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or an acyl group having 2 to 6 carbon atoms which may be substituted by an amino group; M represents a hydrogen atom, an alkali metal atom or an alkaline earth metal atom, provided that R ¹
And R ² are not hydrogen atoms at the same time. A) a substantially water-soluble compound represented by the formula:
About.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION A water-based ink of the present invention is a water-water-soluble organic solvent mixed solution containing a specific neutralized polyester, a water-insoluble colorant (hereinafter referred to as a colorant), and a specific water-soluble substance. It is characterized by comprising an aqueous dispersion obtained by distilling a water-soluble organic solvent (hereinafter, referred to as an organic solvent) from a (water-organic solvent mixed solution).

The polyester used in the present invention is JIS
The acid value based on K 0070 is from 1 to 100 mg KOH / g. If the acid value is less than 1 mgKOH / g, a dispersion in which the coloring material is stably impregnated cannot be obtained. If the acid value exceeds 100 mgKOH / g,
Poor water resistance of ink. The acid value is 20 to 90 mg KO
H / g is more preferable, and 30-80 mgKOH / g is further preferable. In a more preferred embodiment, the acid value is 1
9.9 mg KOH / g of first polyester and acid value of 10 to 10
The use of a second polyester of 0 mgKOH / g in combination can improve the print density and provide a more excellent ink having particularly low heater adhesion. In this case, the ratio of the first polyester to the second polyester is preferably 1/5 to 1/150 weight ratio, and more preferably 1/10 to 1/50 weight ratio, from the viewpoint of the stability of the aqueous dispersion. Is more preferred.

Further, Tg (glass transition point,
DSC (measured by a differential scanning calorimeter)) is preferably 30 ° C. or higher, more preferably 40 ° C. or higher and 150 ° C. or lower, from the viewpoint of solidification in the nozzles and prevention of ink reflection on the paper. The number average molecular weight of the polyester (in terms of gel permeation chromatography polystyrene conversion) is preferably from 1,000 to 50,000, more preferably from 2,000 to 15,000. It is preferable from the viewpoint of fixability and stability of the dispersion.

The polyester is not particularly limited, and includes, for example, a polyol component (hereinafter, referred to as component (p)) and a polyvalent carboxylic acid derivative [hereinafter, referred to as component (q)].
What is necessary is just what was co-condensation-polymerized, especially the general formula (4):

[0011]

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Wherein R is an alkyl group having 1 to 4 carbon atoms, A is an alkylene group having 2 to 4 carbon atoms, x and y are integers of 1 or more, and the average value of x + y is 2 to 10 The diol component having a diol represented by the following formula as a main component and the component (q) are preferably subjected to co-condensation polymerization. In addition, in this specification, "(q) component (polyhydric carboxylic acid)" means one or more types selected from the group consisting of polyhydric carboxylic acids, acid anhydrides thereof, and lower alkyl esters thereof.

In the component (p), the diol component represented by the general formula (4) is not particularly limited, but is an alkylene oxide adduct of bisphenol A, preferably an ethylene oxide or propylene oxide adduct of bisphenol A. Yes, specifically, polyoxypropylene (2.
2) -2,2-bis (4-hydroxyphenyl) propane, polyoxyethylene (2.0) -2,2-bis (4
-Hydroxyphenyl) propane and the like.

In the component (q), the polyvalent carboxylic acid is not particularly restricted but includes, for example, divalent and trivalent carboxylic acids, preferably maleic acid, fumaric acid, itaconic acid, Examples include divalent carboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, succinic acid, and dimer acid, and trivalent carboxylic acids such as 1,2,4-benzenetricarboxylic acid and trimellitic anhydride. As the lower alkyl ester of these polycarboxylic acids, an alkyl ester having 1 to 4 carbon atoms is preferably used.

As used herein, the term "dimer acid" refers to a substance synthesized by a polymerization reaction of two molecules of unsaturated fatty acids, such as acyclic dimer acid, monocyclic dimer acid, and bicyclic dimer acid. It is commercially available as a mixture containing

The molecular weight of the polyester can be adjusted by adding a monovalent carboxylic acid or a monohydric alcohol in an appropriate amount.

The copolycondensation of the component (p) and the component (q) can be carried out by a known method, for example, by reacting the component (p) with the component (q) at 180 to 250 ° C. in an inert gas atmosphere. The reaction may be performed at a temperature, and the end point may be determined by tracking a softening point, an acid value, or the like, which serves as a reference for the molecular weight. The molar ratio between the component (p) and the component (q) cannot be unconditionally defined by the acid value, number average molecular weight, Tg, etc. of the polyester, but the acid value based on JIS K 0070 is 1 to 1. The component (p) and the component (q) can be freely combined and selected within the above range of 100 mgKOH / g.

At this time, zinc oxide, stannous oxide,
Additives such as esterification catalysts such as dibutyltin oxide and dibutyltin dilaurate, and polymerization inhibitors such as hydroquinone monomethyl ether can be used as appropriate.

The polyester used in the present invention is preferably a neutralized product. For example, a neutralizing agent is added to a polyester solution to obtain a neutralized product. The neutralizing agent is not particularly limited as long as it can ionize the acid group of the polyester,
Preferably, hydroxides and various amines of alkali metals and alkaline earth metals, the amount used is not particularly limited,
For example, with respect to the carboxyl group of the polyester, 0.1.
The equivalent ratio is preferably 8 to 1.2.

The content of the polyester in the aqueous ink of the present invention is desirably 1% by weight or more, preferably 2% by weight or more from the viewpoint of durability. 50% by weight or less, preferably 30% by weight, from the viewpoint of suppressing clogging of
It is desirable that:

Next, the coloring material used in the present invention will be described. In this specification, “colorant (water-insoluble colorant)”
The term “colorant” means a coloring material that is almost insoluble or hardly soluble in water, and examples thereof include dyes and pigments such as oil-soluble dyes and disperse dyes. In particular, oil-soluble dyes and disperse dyes are preferred from the viewpoint of their adsorption to polyester.

The oil-soluble dye is not limited to the following, but particularly preferred specific examples are CI Solvent Black Series; CI Solvent Yellow Series;
I. Solvent Red Series; CI Solvent Bio Red Series; CI Solvent Blue Series; CI Solvent Green Series; and CI Solvent Orange Series.

The disperse dyes are not limited to the following, but particularly preferred specific examples are CI Disperse Yellow Series; CI Disperse Orange Series; CI Disperse Red Series; CI Disperse Bio Red Series; CI Disperse Blue Series. And CI Disperse Green Series.

Such a dye is added to an organic solvent in an amount of 20 g /% in order to be efficiently adsorbed to the polyester during the phase inversion emulsification described below.
It is preferable to dissolve one or more, more preferably 40 to 600 g / 1.

The pigment is not particularly limited, and known pigments such as azo pigments, phthalocyanine pigments, anthraquinone pigments and carbon black pigments can be used. The particle size of the pigment may be any particle size that can be adsorbed to the micelles of the polyester.

The content of the coloring material in the aqueous ink of the present invention is as follows:
In order to obtain a sufficient print density, the content is desirably 1% by weight or more, preferably 1.5% by weight or more, and from the viewpoint of dispersion stability of the ink, 30% by weight or less, preferably 25% by weight or less. It is desirable that

Next, c) used in the present invention will be described. c) is a water-based polyhydric hydroxy compound having a boiling point higher than that of water (hereinafter referred to as "c"), which has the function of improving the liquid stability and enhancing the ejection properties of the ink in addition to imparting moisture retention to the aqueous ink of the present invention. , C1)) and the general formula (1)
And at least one compound selected from the group consisting of substantially water-soluble compounds represented by (3) and amino acids and salts thereof (hereinafter, referred to as c2). In this specification, “substantially soluble in water” means that 20 g or more is dissolved in 1 liter of water at room temperature.

Examples of c1) include, but are not particularly limited to, glycols such as ethylene glycol, propylene glycol, diethylene glycol and polyethylene glycol; glycerin; diethylene glycol diethyl ether, ethylene glycol monomethyl ether, ethylene glycol monobutyl ether; Examples thereof include ethers of polyhydric alcohols such as methyl carbitol, ethyl carbitol, and propylene glycol monomethyl ether. Among them, di- and tri-alcohols having 2 to 10 carbon atoms and ethers thereof are preferable. Particularly preferred are polyhydric hydroxy compounds of Nos. 1 to 4.

In c2), formulas (1) to (1)
In the compound represented by (3), examples of R ^{1 to} R ⁴ include a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, and an acyl group having 2 to 6 carbon atoms which may be substituted by an amino group. And R include an alkylene group having 1 to 5 carbon atoms, and an alkylene group having 1 to 2 carbon atoms is preferable.

Examples of M include a hydrogen atom, an alkali metal atom, an alkaline earth metal atom, and an alkylamine having 2 to 10 carbon atoms which may be substituted with a hydroxyl group. Particularly, a hydrogen atom or an alkali metal atom, triethylamine, Dimethylethanolamine and triethanolamine are preferred.

As the compound represented by the general formula (1),
In terms of ink ejection, clogging prevention and liquid stability, N-
Methylglycine is particularly preferred. As the compound represented by the general formula (2), particularly, trimethylglycine is preferable in terms of ink ejection properties and clogging prevention properties. General formula (3)
As the compound represented by the formula, urea is particularly preferred in terms of ink ejection properties, clogging prevention properties, and ink viscosity increase prevention properties. In c2), the compound represented by the general formula (1) is particularly preferable.

The compound of c2) also includes amino acids and salts thereof. Examples of the amino acids include β-alanine, L-proline, ε-aminocaproic acid, α-aminobutyric acid, and 8-amino-caprylic acid. The salt is preferably, for example, an alkali metal salt, an alkaline earth metal salt, or an alkylamine having 2 to 10 carbon atoms which may be substituted with a hydroxyl group.

As c), at least one of c1) and c2) may be used, but from the viewpoint of efficiently achieving the object of the present invention, at least one selected from c1) and c2). It is preferable to include one selected from the group consisting of: The amount of c) is preferably at least 1% by weight, and more preferably at least 10% by weight, based on polyester, from the viewpoint of suppressing a decrease in liquid stability.
From the viewpoint of suppressing a decrease in ink ejection property, scratch resistance, etc., 15
It is desirably 0% by weight or less, preferably 100% by weight or less.

Next, the organic solvent used in the present invention will be described. As the organic solvent, those which dissolve at least 10 parts by weight with respect to 100 parts by weight of water at 20 ° C. are preferable and are not particularly limited, but ketones having a total carbon number of 3 to 8 such as acetone, methyl ethyl ketone, diethyl ketone, etc. Preferred are solvents such as ether solvents having a total carbon number of 4 to 8, such as tetrahydrofuran, and more preferred are acetone, methyl ethyl ketone and tetrahydrofuran.

Next, the aqueous dispersion of the present invention will be described. The aqueous dispersion is a dispersion of polyester fine particles having a coloring material adsorbed thereon. In the present specification, the expression "color material is adsorbed" means either or both of a state in which the color material is encapsulated in the polyester fine particles and a state in which the color material is adsorbed on the surface of the polyester fine particles. It is not necessary that all the coloring materials incorporated in the aqueous ink of the present invention be encapsulated or adsorbed in the polyester fine particles, and the coloring materials are dispersed in the dispersion liquid as long as the effects of the present invention are not impaired. Is also good.

Next, a method for producing the water-based ink of the present invention will be described. The water-based ink of the present invention is a so-called phase-inversion emulsification, that is, a water-organic solvent mixed solution containing a neutralized product of polyester, a coloring material, and a water-soluble substance represented by c), and the organic solvent is distilled off to form a water-based ink. It is manufactured by phase inversion. A more preferred production method is to add a polyester to an organic solvent together with a coloring material, add a neutralizing agent to ionize carboxyl groups in the polyester, and then add water containing a water-soluble compound represented by c), It consists of evaporating the solvent and inverting the phase to an aqueous system. Phase inversion may occur when water is added,
From the viewpoint of obtaining a stable dispersion, it is more preferable that the reaction occurs during the distillation of the organic solvent.

Specifically, first, polyester is added to an organic solvent together with a coloring material. In this case, each of the polyester and the coloring material is 5 to 5 parts by weight with respect to 100 parts by weight of the organic solvent.
It is preferable to dissolve 0 parts by weight and 0.1 to 50 parts by weight from the viewpoint of forming a dispersion liquid. Next, after adding a neutralizing agent, water containing a water-soluble substance shown in c) is added to the mixture. The amount of water is 100 to 100 parts by weight of the organic solvent.
Preferably it is 300 parts by weight. In this case, various known anions and nonionic surfactants in water, particularly β
It is preferable to further add a salt of a formalin condensate of naphthalenesulfonic acid because the average particle diameter of the polyester fine particles can be reduced. The amount of surfactant added
An amount that is 0.01 to 10% by weight in the finally obtained ink is preferable.

After preparing the water-organic solvent mixed solution, the organic solvent is distilled off while heating the system under reduced pressure to about 30 to 70 ° C. to reduce the solvent content to 5% by weight or less, preferably 3% by weight. %, The water-based ink of the present invention can be obtained. Further, a predetermined amount of water can be distilled off to adjust the concentration of the water-based ink. The pH of the water-based ink is
It is preferable to adjust the pH to 5 to 12 in order to secure the stability of the dispersion.

The particle size of the fine particles of the polyester is desirably 0.1 nm or more, preferably 5 nm or more, from the viewpoint of suppressing the occurrence of ink bleeding, and is 500 nm or less, preferably, for ensuring dispersion stability. Is desirably 300 nm or less. The particle size of the polyester fine particles can be adjusted by, for example, changing the conditions of phase inversion emulsification.

In addition to the above-mentioned components, the water-based ink of the present invention contains various conventionally known additives such as acetylenol E
H (manufactured by Kawaken Fine Chemical Co., Ltd.), UV absorbers such as benzotriazole, benzophenone, salicylate, cyanoacrylate, fungicides such as chloromethylphenol, chelating agents such as EDTA, sulfurous acid An oxygen absorber such as a salt, a crystallization inhibitor such as trimellitic acid-tri-2-ethylhexyl and the like may be blended.

The water-based ink of the present invention obtained by such a method is particularly useful as a water-based ink for ink-jet recording, but can also be used as an ink for general writing implements such as a fountain pen, a ball-point pen, and a felt-tip pen. is there.

[0042]

EXAMPLES Production Example 1 Production of Polyester Polyoxypropylene (2.2) -2,2-bis (4-
1050 g of hydroxyphenyl) propane, 30% of acyclic dimer acid compound and 10% of monocyclic dimer acid compound
90 g of a dimer acid mixture containing
g, hydroquinone 0.8 g, dibutyltin oxide 2.3 g
The mixture was reacted for 8 hours while stirring at 210 ° C. under a nitrogen stream, and then 120 g of trimellitic anhydride was added. When the acid value reached 48 mgKOH / g, the reaction was terminated. The obtained polyester (hereinafter, referred to as polyester) was a pale yellow solid, had a Tg of 52.5 ° C, a softening point of 98 ° C, and a number average molecular weight of 3,600.

Production Example 2 [Production of Polyester] Polyoxypropylene (2.2) -2,2-bis (4-
Production except that 735 g of (hydroxyphenyl) propane, 315 g of polyoxyethylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, 300 g of terephthalic acid, 80 g of trimellitic anhydride, and 2.1 g of hydroquinone were used. The reaction was carried out in the same manner as in Example 1 and the acid value was 3
When the concentration reached mg KOH / g, the reaction was terminated to obtain a polyester (solid, pale yellow in appearance, Tg: 65 ° C, softening point: 140).
° C, number average molecular weight: 6000)

Example 1 150 g of the polyester obtained in Production Example 1 and an oil-soluble dye (OIL BLACK 860 manufactured by Orient Chemical)
After completely dissolving 70 g in 500 g of tetrahydrofuran, 12.60 g of dimethylethanolamine and 1.03 g of sodium hydroxide were added. Furthermore, ion-exchanged water 9
60 g, a mixed aqueous solution of 3 g of β-naphthalenesulfonic acid formalin condensate (manufactured by Kao Corporation, Demol N) and 50 g of N-methylglycine were added dropwise, and the mixture was stirred.
The mixture was heated to 0 ° C. to distill off tetrahydrofuran to obtain a dispersion (average particle diameter: 20 nm, solid content: 20% by weight) of a polyester into which a coloring agent (oil-soluble dye) was introduced. The resulting dispersion was filtered through a 1000 nm filter to obtain an aqueous ink for inkjet recording having the following composition.・ Polyester dispersion 60.0g ・ Diethylene glycol 9.5g ・ Glycerin 10.0g ・ Ion exchange water 20.0g ・ Acetyleneol EH 0.5g

Example 2 As a water-based ink raw material, 100 g of an oil-soluble dye was used.
A dispersion liquid of polyester (average particle size: 32 nm, solid content: 20% by weight) was obtained in the same manner as in Example 1 except that 50 g of methylglycine was further added to 50 g of glycerin. Using this dispersion, a water-based ink for inkjet recording was obtained in the same manner as in Example 1 with the following composition.・ Polyester dispersion 60.0 g ・ N-methylglycine 15.0 g ・ Sodium octyl sulfate 2.0 g ・ Ion-exchanged water 22.5 g ・ Acetylenol EH 0.5 g

Example 3 As aqueous ink raw materials, 150 g of the polyester obtained in Production Example 1 and the polyester obtained in Production Example 2 were used.
5 g, oil-soluble dye 110 g, trimellitic acid-tri-2
Example 1 except that 7.5 g of -ethylhexyl (manufactured by Kao Corporation, T-08) and 650 g of tetrahydrofuran were used.
In the same manner as described above, the carboxyl groups in the polyester and in the polyester were neutralized. Further, a mixed aqueous solution of 960 g of ion-exchanged water, 3 g of β-naphthalenesulfonic acid formalin condensate, 50 g of N-methylglycine, 50 g of glycerin and 50 g of urea was added dropwise and stirred, and then heated to 40 ° C. under reduced pressure to remove tetrahydrofuran. This was removed to obtain a dispersion (average particle size: 32 nm, solid content: 20% by weight) of a polyester into which a coloring agent (oil-soluble dye) was introduced. A water-based ink for ink-jet recording was obtained in the same manner as in Example 1, except that this dispersion was used.

Example 4 50 g of trimethylglycine and 50 g of ethylene glycol were used instead of 50 g of N-methylglycine and 50 g of glycerin.
A polyester dispersion (average particle size: 32 nm, solid content: 20% by weight) into which a coloring agent (oil-soluble dye) was introduced was obtained in the same manner as in Example 3 except that 0 g was used. Using this dispersion, a water-based ink for inkjet recording was obtained in the same manner as in Example 1 with the following composition.・ Polyester dispersion 60.0g ・ Trimethylglycine 15.0g ・ Sodium octyl sulfate 1.0g ・ Ion exchanged water 23.9g ・ Sodium dioctyl sulfosuccinate 0.1g

Comparative Example 1 A polyester dispersion was prepared in the same manner as in Example 1 except that N-methylglycine was not added. However, a precipitate was formed in the dispersion. (Average particle size 62 nm, solid content 13% by weight). A water-based ink for inkjet recording was obtained in the same manner as in Example 1 except that this dispersion was used.

Comparative Example 2 A polyester dispersion was prepared in the same manner as in Example 3 except that N-methylglycine, glycerin and urea were not added. However, a precipitate was formed in the dispersion. Thus, a dispersion (average particle size: 78 nm, solid content: 11% by weight) was obtained. A water-based ink for inkjet recording was obtained in the same manner as in Example 1 except that this dispersion was used.

Using the inks of Examples 1 to 4 and Comparative Examples 1 and 2, printing was performed using a commercially available Canon color bubble jet printer (model number BJC-430J, the same applies hereinafter). The liquid properties were evaluated and the results are summarized in Table 1.

[Printing Evaluation] <Printing Density> Solid printing was carried out on recycled paper for PPC (manufactured by Nippon Kikai Seiyaku Co., Ltd .; the same applies hereinafter), and after natural drying in a room for 24 hours, the optical density was measured as the Macbeth density. It was measured with a total of RD918 (manufactured by Macbeth Co., Ltd .; the same applies hereinafter).

[Ink Jet Suitability] <Ink Ejection Rate> Solid printing is performed on PPC recycled paper, the weight of the ink cartridge before and after printing is measured, and the ink ejection amount is calculated from the change amount. The ratio of the genuine ink to the ink discharge amount when the genuine ink was used was calculated as the ink discharge ratio.

<Clogging Prevention> After printing continuously for 10 minutes, the sample was left for 2 weeks without capping in an environment of 35 ° C. and 25% relative humidity (RH). Next, printing was performed, and the number of times of clogging recovery operation (cleaning) required until printing equivalent to that before standing was obtained was examined. In the table, ◎ indicates no return operation, は indicates 1-2 times, Δ indicates 3-5 times, and X indicates 6 times or more.

<Heater Adhesion> After printing 50 sheets of A4 solid color continuously, the heater portion in the printer head was observed with a microscope and a stylus tester, and the amount (height) of the deposit on the heater surface and on the heater edge was measured. .

<Print head dirt> Continuous 50 sheets A4
After the solid printing, the nozzle portion (ink ejection hole) of the printer head and the peripheral surface of the nozzle were observed with a microscope. In the table, ○ indicates that the nozzle portion was clean and free of deposits, the nozzle peripheral surface was in a water-repellent state, and no deposits were generated. The peripheral surface is in a water-repellent state, indicating that there is no attached matter, and x indicates that the attached matter is generated in the nozzle portion, the peripheral surface of the nozzle is changed to a hydrophilic state, and the attached matter is generated.

[Liquid Properties] <Liquid Stability> The ink was placed in a 50 ° C. constant temperature room for one month, and the particle size distribution of the polyester particles was measured using a Coulter counter (CO
ULTER ELECTRONICS: Product name: COULTER MODEL N4)
And the liquid stability was evaluated. In the table, ◎ indicates no change in the particle size distribution, and the average particle size is 0.1 in the monodispersed system.
μm or less, ○ indicates that the change in particle size distribution is subtle,
The average particle diameter is 0.1 μm or less in a monodisperse system, Δ indicates a change in particle diameter distribution, and a polydisperse system having a distribution of two peaks or more indicates an average particle diameter of 0.2 μm or less, and X indicates a liquid bottom. Shows that an aggregate precipitate is generated.

<Drying Resistance> A few drops of the ink were dropped on an aluminum cup, dried at room temperature, and the time until a film was formed was measured.

[0058]

[Table 1]

From the results shown in Table 1, all of the inks obtained in Examples 1 to 4 have higher print density and ink ejection rate than inks obtained in Comparative Examples 1 and 2, and are excellent in clogging prevention. It can be seen that an ink having low heater adhesion, little printer head contamination, and excellent liquid stability and drying resistance can be obtained. In addition, there were no problems in water resistance and marker resistance.

[0060]

By using the ink for ink jet recording of the present invention, the print density and the ink discharge rate are high,
Excellent prevention of clogging and non-sticking of heater
It is possible to obtain an ink jet recording ink which has little stain on the printer head, and has excellent liquid stability and drying resistance.

Claims (4)

[Claims] 1. A water-based ink for ink-jet recording comprising an aqueous dispersion containing a polyester adsorbed with a water-insoluble colorant as a dispersoid, wherein the aqueous dispersion contains the following a), b) and c). A water-based ink for ink-jet recording characterized by being obtained by distilling off the water-soluble organic solvent from a mixed solution of a water-soluble organic solvent, a) neutralized polyester having an acid value of 1 to 100 mgKOH / g ,
b) a water-insoluble colorant; c) one or more compounds selected from the group consisting of c1) and c2); c1) a water-soluble polyhydroxy compound having a boiling point higher than that of water; c2) a general formula (1); Formula (2) and General Formula (3): (Wherein, R ^{1 to} R ⁴ are the same or different and are each a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or an acyl group having 2 to 6 carbon atoms which may be substituted by an amino group; ~ 5
M represents a hydrogen atom, an alkali metal atom or an alkaline earth metal atom. However, R ¹ and R ² are not simultaneously hydrogen atoms. A) a substantially water-soluble compound represented by the formula: and amino acids and salts thereof. 2. The polyester has an acid value of 1 to 9.9 mgKOH /
The water-based ink according to claim 1, comprising a first polyester of the formula (1) and a second polyester having an acid value of 10 to 100 mgKOH / g. 3. A compound wherein c) is selected from c1) and c
2. The aqueous ink according to claim 1, comprising a compound selected from 2). 4. The method according to claim 1, wherein c1) is a polyvalent hydroxy compound having 2 to 4 carbon atoms, and c2) is at least one selected from the group consisting of N-methylglycine, trimethylglycine and urea. Water-based ink.