JPH10273610A - Water-based ink - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject ink that is prevented from bleeding, has improved fixity to the matter to be printed and improved resistance to water and is useful for ink-jet recording by admixing a suspension of a specific polymer having colorants adsorbed thereto. SOLUTION: This ink contains a suspension of a polymer to which colorants are adsorbed where the polymer has an acid value of 3-100 KOHmg/g according to JIS K 0070. The ink is prepared by using a neutralizing agent as dimethanolamine in an amount of satisfying formula I [F (x) is formula II]. The above polymer has a glass transition point of >=20 deg.C and preferably contains a unit derived from a diol component represented by formula III (R is a lower alkyl; A is an alkylene; (x) and (y) are each >=1 where the average value of x+y is 2-10).

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 in which bleeding of the ink is prevented and the fixability to a printing material and the water resistance are improved, and more particularly to a water-based ink useful as an ink for ink jet recording. is there.

[0002]

2. Description of the Related Art Water-based inks are often used for printing and writing implements because of their ease of production and handling. For example, printer devices have become widespread due to the recent development and spread of computers, and water-based inks have been actively used in such printer devices.

As ink used in an ink jet printer which is one of typical printer devices, a water-soluble dye which is usually dissolved in water is used in order to prevent the nozzle from being clogged with ink. The use of the water-soluble dye makes it difficult for the ink to clog the nozzles, but has the problem that the water resistance of the printed matter is poor. Therefore, in order to improve the water resistance of the printed matter, the composition of the ink is important.

In order to improve the water resistance of the ink for ink jet recording, a pigment is used as the ink (Japanese Patent Application Laid-Open Nos. 4-28776, 4-189876, 4-3599071, 4-35972). Gazette, etc.) or using a non-aqueous liquid medium (JP-A-4-26147)
No. 8) and the use of a dye having excellent water resistance (US Pat. No. 4,963,189) has been proposed.

However, when a pigment is used as an ink, there is a possibility that the saturation of a printed matter is reduced, a problem such as clogging in a nozzle may occur, and the fixability to paper or an OHP sheet is insufficient. Thus, there was a problem in the record preservability as a printed matter. Other proposals have not yet obtained an ink which sufficiently satisfies all the required characteristics such as prevention of ink bleeding and water resistance and fixability.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a water-based ink in which bleeding of the ink is prevented, and the fixability to a printing substrate and the water resistance are improved.

Another object of the present invention is to provide a water-based ink which is particularly useful as an ink for ink-jet recording.

[0008]

Means for Solving the Problems The present inventors have made intensive studies and found that the above object can be achieved by an aqueous ink containing a suspension of a specific polymer to which a coloring material has been adsorbed.

The present invention has been made based on the above findings, and is an aqueous ink containing a suspension of a polymer to which a coloring material has been adsorbed.
An acid value based on K0070 of 3 to 100 KOHmg /
g, wherein the ink has been prepared using a neutralizing agent in an amount satisfying the following formula (A), thereby achieving the above object by providing an aqueous ink. .

[0010]

(Equation 2)

The present invention also provides an ink jet recording ink characterized by using the above-mentioned aqueous ink.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The aqueous ink of the present invention contains a suspension of a polymer having a coloring material adsorbed thereon, wherein the polymer has a specific acid value and the ink uses a specific amount of a neutralizing agent. It is characterized by being prepared by: In the water-based ink of the present invention, at least a part of the coloring material is adsorbed on the micelle formed by the polymer or is enclosed in the micelle. That is, in the present specification, "the color material is adsorbed" means that at least a part of the color material is adsorbed on the micelle formed by the polymer or is enclosed in the micelle. The aqueous ink of the present invention comprises the above-mentioned polymer micelles having the coloring material adsorbed therein as a suspension in water.

The above polymer is a polymer having an acid value based on JIS K 0070 of 3 to 100 KOH mg / g. If the acid value is less than 3 KOHmg / g, a suspension stably adsorbing the coloring material cannot be obtained.
If the OH mg / g is exceeded, the fixability of the ink to a printing substrate and the water resistance will decrease. The acid value is preferably 3 to 3 from the viewpoint of improving suspension formability and stability.
70 KOHmg / g, more preferably 10-60
KOH mg / g, more preferably 15 to 45 KO
Hmg / g, and even more preferably 15 to 40 KO.
Hmg / g.

The water-based ink of the present invention is prepared using a neutralizing agent in an amount satisfying the above formula (A). In the above formula (A), F (x) indicates the amount of the neutralizing agent required for neutralizing the polymer (= neutralization amount) [That is, when the neutralizing agent is added in an amount of F (x). The polymer is just neutralized. That is, the above formula (A) shows that the aqueous ink of the present invention
It means that it was prepared using a neutralizing agent in an amount of 0.8 to 1.5 times the neutralizing amount of the polymer. If the used amount of the neutralizing agent is less than 0.8F (x), the suspension is not sufficiently formed, so that the suspension is in an extremely unstable state and aggregates and sediments.
If it exceeds 1.5 F (x), the pH of the ink will be inclined to the strong alkali side, and the phenomenon that the ink bleeds slightly when printing is caused by an excessive neutralizing agent will occur.
The amount of the neutralizing agent used preferably satisfies the following formula (A ′), and more preferably satisfies the following formula (A ″).
The method for preparing the water-based ink of the present invention and the type of the neutralizing agent will be described later.

[0015]

(Equation 3)

When the water-based ink of the present invention is used particularly as an ink for ink-jet recording, the above-mentioned polymer has a Tg measured by DSC (differential scanning calorimetry).
(Glass transition point) is preferably 20 ° C. or higher.
More specifically, when the inkjet method uses a piezoelectric element, the temperature is 20 ° C. or more, and when the inkjet method uses thermal energy, the temperature is 30 ° C. or more. The temperature is more preferably 50 ° C. or more and 150 ° C. or less. When the Tg is within the above range, when the aqueous ink of the present invention is used in an ink jet printer, there is no occurrence of clogging of the nozzle due to the solidification of the polymer in the nozzle of the printer.

The above polymer has a number average molecular weight (converted to polystyrene by gel permeation chromatography) of 500 to 100,000, especially 1000.
A value of from 10,000 to 10000 is desirable from the viewpoints of water resistance and fixing property of the ink after printing and formability of the suspension, and in particular, in the case of using the water-based ink of the present invention in an ink jet printer to prevent scorching on a printer head.

The polymer used in the water-based ink of the present invention preferably contains a unit derived from a diol component represented by the following formula (1) in the polymer chain from the viewpoint of controlling the thermal properties of the polymer. . Specific examples of the polymer containing a unit derived from the diol component will be described later.

[0019]

Embedded image

The polymer is a polymer having the above-mentioned acid value and capable of forming micelles capable of adsorbing the coloring material therein, or at least capable of forming micelles capable of enclosing the coloring material. The type can be used without particular limitation. For example, polyester, polyester polyamide, a polymer of (meth) acrylic acid or a derivative thereof, a polymer of styrene- (meth) acrylic acid or a derivative thereof, polyurethane, polyamide, and the like can be given. In particular, it is preferable to use one selected from one or more of polyester and polyester polyamide from the viewpoint of fixability to paper. Hereinafter, such polyester and polyester polyamide will be described.

[Polyester] The polyester is not particularly limited. For example, a diol component represented by the above formula (1) [hereinafter referred to as component (a)] and a polyvalent carboxylic acid derivative [hereinafter referred to as component (b)] [Polyester (A)] is preferable. In addition, in this specification, a "polyhydric carboxylic acid derivative" means polyhydric carboxylic acid, its acid anhydride, or its lower alkyl ester.

The diol component represented by the above formula (1), which is the component (a), will be described. The diol component is not particularly limited.
Alkylene oxide adduct, preferably an ethylene oxide or propylene oxide adduct of bisphenol A, specifically, polyoxypropylene (2.2)
-2,2-bis (4-hydroxyphenyl) propane,
Polyoxypropylene (3.3) -2,2-bis (4-
(Hydroxyphenyl) propane, polyoxyethylene (2.0) -2,2-bis (4-hydroxyphenyl)
Propane, polyoxypropylene (2.0) -polyoxyethylene (2.0) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene (6)-
2,2-bis (4-hydroxyphenyl) propane and the like can be preferably used.

Next, the polyvalent carboxylic acid derivative, which is the component (b), is not particularly limited, and may be one selected from the group consisting of a polyvalent carboxylic acid, an acid anhydride thereof and a lower alkyl ester thereof. The above is used.

As the polyvalent carboxylic acid, divalent carboxylic acids and trivalent or higher carboxylic acids are used. The divalent carboxylic acid is not particularly limited, but includes, for example, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, succinic acid, adipic acid, sebacin Acid, azelaic acid, malonic acid, n-dodecenyl succinic acid, isododecenyl succinic acid, n-dodecyl succinic acid, isododecyl succinic acid, n-octenyl succinic acid, n-octyl succinic acid, isooctenyl succinic acid, dimer acid, isomeric Octyl succinic acid and the like are preferably used. On the other hand, the trivalent or higher carboxylic acid is not particularly limited, and for example, 1,2,4-benzenetricarboxylic acid, 2,2
5,7-naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 1,2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-
Dicarboxyl-2-methyl-2-methylenecarboxypropane, 1,2,4-cyclohexanetricarboxylic acid, tetra (methylenecarboxyl) methane, 1,2,2
7,8-octanetetracarboxylic acid, pyromellitic acid,
Trimellitic anhydride, embolic trimer acid and the like are preferably used. As the lower alkyl ester of these polyvalent carboxylic acids, an alkyl ester having 1 to 4 carbon atoms is preferably used. In particular, as the polyvalent carboxylic acid, a divalent carboxylic acid such as maleic acid, fumaric acid, itaconic acid, phthalic acid, isophthalic acid, terephthalic acid, succinic acid, dimer acid, or 1,2,4-benzenetricarboxylic acid It is preferable to use an acid or trimellitic anhydride.

The polyester includes a diol component represented by the above formula (1) (that is, the component (a)), a dimer acid (hereinafter, referred to as a component (b) ′),
Polyvalent carboxylic acid derivatives other than dimer acid (hereinafter, referred to as
(B) A component obtained by co-condensation polymerization of the “component” is also preferable (this polyester is hereinafter referred to as polyester (B)).

The component (a) used in the polyester (B) includes the same components as those used in the polyester (A). In the description of the dimer acid as the component (b) ′, “dimer acid” in this specification refers to a substance synthesized by a polymerization reaction of two molecules of unsaturated fatty acids. Examples of the dimer acid include acyclic dimer acids represented by the following formulas (I) and (II), and the following formula (III)
), (IV) and (V) monocyclic dimer acids,
In addition, bicyclic dimer acids represented by the following formulas (VI) and (VII) can be used. By using the dimer acid as the copolycondensation component in the polyester, the formability and stability of the suspension are improved, and the amount of colorant adsorbed is improved. The dimer acids may be used alone or in combination of two or more. As the dimer acid, commercially available products can also be used. Such commercial products generally include acyclic dimer acids represented by the following formulas (I) and (II), and monocyclic dimer acids represented by the following formulas (III), (IV) and (V): Consisting of a dimer acid and a complex mixture of bicyclic dimer acids represented by the following formulas (VI) and (VII):
Unidim 22 (trade name, acyclic rich type) manufactured by Union Cap, Haridimmer 250K manufactured by Harima Kasei
(Trade name, monocyclic / bicyclic rich type) and the like.

[0027]

Embedded image

[0028]

Embedded image

[0029]

Embedded image

Of the above-mentioned dimer acids, it is preferable to use an acyclic dimer acid as a main component from the viewpoint of improvement in suspension formability and stability, and particularly to use a dimer acid represented by the formula (I). preferable.

The component (b) "used in the polyester (B) is the same as the component (b) used in the polyester (A) except for dimer acid. be able to.

In the polyester (B), the molar ratio of the component (a), the component (b) ′, and the component (b) ″ is determined by the acid value, the number average molecular weight and the Tg of the polyester (B). The above components may be freely combined and selected within a range where Tg is 20 ° C. or higher, although the value of the component (b) ′ is particularly preferable.
It is preferably from 0.001 to 0.7 mol, more preferably from 0.01 to 0.5 mol, per 1 mol of the component (a). On the other hand, the component (b) ″ is preferably 0.3 to 1.2 mol, more preferably 0.5 to 1.1 mol, per 1 mol of the component (a).

[Polyester Polyamide] The polyester polyamide comprises a diol component represented by the above formula (1) (namely, the component (a)), a polyvalent carboxylic acid derivative [namely, the component (b)], Amine derivatives [hereinafter,
(Referred to as component (c))].

As the component (a) used in the polyester polyamide, those similar to those used in the polyester (A) and the polyester (B) can be mentioned. The component (b) used in the polyester polyamide includes the same components as those used in the polyester (A).

The amine derivative which is the component (c) used in the polyester polyamide is not particularly limited as long as it is an amine which can be co-condensed with the components (a) and (b). be able to. Examples of such amines include polyamines such as ethylenediamine, pentamethylenediamine, hexamethylenediamine, diethylenetriamine, iminobispropylamine, phenylenediamine, xylylenediamine and triethylenetetramine; 6-aminocaproic acid and ε-caprolactam And amino alcohols such as propanolamine.

In the above polyester polyamide,
The molar ratio of the component (a), the component (b), and the component (c) depends on the acid value, number average molecular weight, Tg, and the like of the polyester polyamide. It is preferably from 0.6 to 1.2 mol, more preferably from 0.8 to 1.1 mol, per 1 mol of the component (a). On the other hand, the component (c) is preferably 0.05 to 0.7 mol, more preferably 0.1 to 0.5 mol, per 1 mol of the component (a).

In the above-mentioned polyester and polyester polyamide, for example, each of the co-condensation polymerization components at the time of co-condensation polymerization [components (a), (b), (b) ′,
The acid value, Tg, number average molecular weight and the like are adjusted by changing the addition ratio of (b) "and (c)], using a carboxylic acid ester, or blocking the acid with a monohydric alcohol. The method of the above-mentioned copolycondensation is not particularly limited, and a known method can be used.

In the water-based ink of the present invention, the polymer is preferably incorporated in the ink in an amount of 1 to 50% by weight, more preferably 2 to 30% by weight. If the amount of the polymer is less than 1% by weight, the print density is insufficient. If the amount is more than 50% by weight, the storage stability of the suspension as ink deteriorates. The printer head may be clogged due to thickening of the ink and aggregation of the suspension due to the evaporation of the ink at the leading end portion.

Next, the coloring material adsorbed by the polymer micelles will be described. As the colorant, any colorant that can be adsorbed by the polymer can be used without particular limitation, for example, an oil-soluble dye, a disperse dye,
Dyes and pigments such as direct dyes, acid dyes and basic dyes can be mentioned. In particular, it is preferable to use an oil-soluble dye and a disperse dye from the viewpoint of good encapsulation. The disperse dye is not limited to the following, but particularly preferred specific examples include C.I. I. Disperse Yellow 5, 42, 54, 64, 79, 82, 83, 9
3, 99, 100, 119, 122, 124, 126,
160, 184: 1, 186, 198, 199, 20
1, 204, 224 and 237; I. Disperse Orange 13, 29, 31: 1, 33, 49, 54,
55, 66, 73, 118, 119 and 163;
I. Disperse Red 54, 60, 72, 73, 8
6, 88, 91, 92, 93, 111, 126, 12
7, 134, 135, 143, 145, 152, 15
3, 154, 159, 164, 167: 1, 177, 1
81, 204, 206, 207, 221, 239, 24
0, 258, 277, 278, 283, 311, 32
3, 343, 348, 356 and 362; I. Disperse Violet 31, 33; I. Dispers Blue 36, 56, 60, 73, 87, 113,
128, 143, 148, 154, 158, 165, 1
65: 1, 165: 2, 176, 183, 185, 19
7, 198, 201, 214, 224, 225, 25
7, 266, 267, 287, 354, 358, 365
And 368; and C.I. I. Disperse Green 6: 1 and 9; The oil-soluble dye is not limited to the following, but particularly preferred specific examples include, for example, C.I. I. Solvent Black 3, 7, 27, 29 and 34; C.I. I. Solvent Yellow 14, 16, 19, 21, 25, 29, 30, 5
6, 82, 93 and 162; I. Solvent Red 1, 3, 8, 18, 19, 24, 27, 43, 49,
51, 72, 73, 83, 109, 112, 117, 1
22, 132, 138 and 218; I. Solvent Violet 3; C.I. I. Solvent Blue 2, 1
1, 25, 35, 38, 63, 67, 70, 95 and 1
17; I. Solvent Green 3 and 7; and C.I. I. Solvent Orange 2 and the like. The direct dye is not limited to the following,
Particularly preferred specific examples include, for example, C.I. I. Direct Black 19 and the like. The acidic dye is not limited to the following, but particularly preferred specific examples include, for example, C.I. I. Acid Black 2 and 52; I. Acid Yellow 23;
I. Acid Red 51, 87 and 92; and C.I.
I. Acid Blue 1, 9 and 74. The basic dye is not limited to the following, but particularly preferred specific examples include, for example, C.I.
I. Basic yellow 2 and 11; I. Basic red 1 and 13; I. Basic violet 1, 3, 7, and 10; and C.I. I. Basic Blue 5, 7, 9 and 26, and the like.

The dye used in the present invention is preferably 20 g / l or more in a solvent, for example, a ketone-based solvent, from the viewpoint of being efficiently adsorbed by the above-mentioned polymer, particularly the above-mentioned polyester or polyester polyamide, by phase inversion emulsification described below. It is preferable to dissolve, more preferably 40 g / l or more,
More preferably 50 g / l or more, more preferably 60 g / l
/ L, more preferably 100 to 600 g / l.

On the other hand, as the pigment, any conventionally known organic and inorganic pigments can be used as long as they can be adsorbed by the polymer. For example, azo pigments such as azo lakes, insoluble azo pigments, condensed azo pigments, and chelated azo pigments; phthalocyanine pigments; perylene and perinone pigments; anthraquinone pigments; quinacridone pigments; dioxazine pigments; thioindigo pigments; Dye lakes such as cyclic pigments, basic dye lakes, and acid dye lakes; organic pigments such as nitro pigments, nitroso pigments, aniline black, and daylight fluorescent pigments; titanium oxide, iron oxides, and carbon blacks Inorganic pigments. In addition, any pigment that is not described in the color index can be used as long as it can be dispersed in the aqueous phase. Further, those obtained by subjecting the above pigment to a surface treatment with a surfactant, a polymer dispersant or the like, or graft carbon, etc., can of course be used. Among the above pigments,
Azo pigments, phthalocyanine pigments, anthraquinone pigments,
It is preferable to use a carbon black pigment.

In the present invention, the above-mentioned dyes and pigments may be used alone or in combination. When both are used in combination, the mixing ratio (weight) of the dye and the pigment is the former: the latter = 10: 9
It may be freely selected in the range of 0 to 90:10. In the present specification, "pigment" refers to fine particles of solid insoluble in water, solvent, oil, etc., whereas "dye" is dyed in a state dissolved in water or solvent. [Chemical Encyclopedia of Color Chemistry, March 1988, 1st printing, edited by CMC Co., Ltd., Synthetic Organic Chemistry Association, p. 45].

The average particle diameter of the suspension of the polymer having the coloring material adsorbed thereon is preferably 5 to 500 nm. If the average particle diameter is less than 5 nm, ink bleeding may occur. If the average particle diameter exceeds 500 nm, the dispersion stability of the suspension itself may be reduced. The average particle diameter is 5 to 30 from the viewpoint of suspension formability and stability.
0 nm, more preferably 5 to 2 nm.
00 nm, and more preferably 10 to 100 nm. The average particle diameter can be adjusted, for example, by changing the conditions of phase inversion emulsification described below. In addition, the polymer suspension has the following particle size distribution to ensure storage stability of the liquid when formed into ink, to prevent clogging in the nozzle of the printer head, and to secure fixability as a printed matter. Particularly preferred from the point of view. [Particle size distribution] 60 to 100% of particles having a particle size of 100 nm or less 0 to 10% of particles having a particle size of 200 nm or more The measuring method of the average particle size and the particle size distribution of the polymer suspension is described later. This will be described in detail in an example.

The above-mentioned coloring material is contained in the water-based ink of the present invention by 1 to 1.
Preferably, it is blended at 30% by weight, more preferably 1.5 to 25% by weight. If the amount of the coloring material is less than 1% by weight, the printing density is insufficient,
Even if used in excess of weight%, the print density cannot be significantly improved, and the stability of suspension particle diameter over time decreases, and the average particle diameter tends to increase. preferable.

The water-based ink of the present invention uses water (preferably ion-exchanged water) as a medium, and contains a polymer suspension having the coloring material adsorbed thereon, as well as various conventionally known additives such as polyvalent water. Wetting agents such as alcohols,
Dispersing agents, defoaming agents such as silicones, surface tension regulators such as various cationic, anionic or nonionic surfactants, fungicides such as chloromethylphenol and / or E
It may contain a chelating agent such as DTA, an oxygen absorber such as sulfite, or an ultraviolet absorber such as triazole or benzophenone.

The wetting agent is not particularly limited, but may be, for example, glycols such as ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol and polyethylene glycol; glycerin; diethylene glycol diethyl ether. , Diethylene glycol monobutyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, methyl carbitol, ethyl carbitol, butyl carbitol, ethyl carbitol acetate, diethyl carbitol, triethylene glycol monomethyl ether, triethylene Glycol monoethyl ether and propylene glycol monomethyl Ethers of polyhydric alcohols such as ether, acetates; thiodiglycol; N- methyl -
2-pyrrolidone; 1,3-dimethylimidazolidinone;
Triethanolamine; formamide; nitrogen-containing compounds such as dimethylformamide, amino acids such as glycine, methylglycine, leucine, proline, ε-amino-n-caproic acid, alanine and phenylalanine, and one or more of dimethylsulfoxide. Can be used. There is no particular limitation on the amount of these wetting agents,
0.1 to 50% by weight in the aqueous ink of the present invention
It can be blended, more preferably 0.1 to 30% by weight.

The dispersing agent is not particularly limited. Examples of the anionic surfactant include higher fatty acid salts, higher alkyl dicarboxylates, higher alcohol sulfates, higher alkyl sulfonates, and the like. As a cationic surfactant such as a condensate salt of a higher fatty acid and an amino acid, a sulfosuccinate ester salt, a naphthenate salt, an amphoteric surfactant such as an aliphatic amine salt, a quaternary ammonium salt, a sulfonium salt, and a phosphonium salt,
Examples of the nonionic surfactant such as a betaine compound include a fatty acid ester type of a polyoxyethylene compound and a polyethylene oxide condensed type. When used, one or more of these may be used. Also,
As a polymer dispersant, gelatin, proteins such as casein, natural gums such as gum arabic, glucoxides such as saponin, methyl cellulose, carboxymethyl cellulose, cellulose derivatives such as hydroxymethyl cellulose, lignin sulfonate, natural polymers such as shellac,
Polyacrylate, styrene-acrylic acid copolymer salt,
Vinyl naphthalene-acrylic acid copolymer salt, styrene-
Maleic acid copolymer salt, vinyl naphthalene-maleic acid copolymer salt, naphthalene sulfonic acid formalin condensate salt, special aromatic sulfonic acid formalin condensate salt, anionic polymer such as polyphosphoric acid, polyvinyl alcohol, polyvinyl pyrrolidone And non-ionic polymers such as polyethylene glycol. When used, one or more of these can be used. Above all, it is particularly preferable to contain a β-naphthalenesulfonic acid formalin condensate represented by the following formula (2), since the average particle diameter of the suspension can be reduced and the dispersion stability of the suspension can be improved.

[0048]

Embedded image

In the above formula (2), a hydrogen atom is preferably used as R ′. M is preferably an ion of an alkali metal such as sodium and potassium. Also, l is preferably 100 to 800.
The compound represented by the above formula (2) has an HLB value of 5 to 5.
A value of 15 is preferred from the viewpoint that the effect as a dispersant is exhibited and the effect of suppressing an increase in the average particle diameter of the suspension is obtained.

As the compound represented by the above formula (2), commercially available products can also be used. As such a commercially available product, for example, a dispersant Demol SNB, M manufactured by Kao Corporation
S, N, SSL, ST, P, C (all are trade names).

The amount of the dispersant is not particularly limited,
In the aqueous ink of the invention, it is usually incorporated in an amount of 0.01 to 10% by weight. If the amount of the dispersant is less than 0.01% by weight, it is difficult to reduce the particle size of the suspension, and if it exceeds 10% by weight, the average particle size of the suspension increases or the suspension stability decreases, Therefore, it is preferable that the content is within the above range. Preferably, the compounding amount of the dispersant in the aqueous ink of the present invention,
It is 0.05 to 5% by weight, further 0.1 to 1% by weight.

The defoaming agent is not particularly limited, but a compound represented by the following formula (3), particularly, a compound represented by the following formula (4) may be used. It is particularly preferable in terms of suppressing generation and adjusting the surface tension of the ink.

[0053]

Embedded image

[0054]

Embedded image

In the above formula (3), R ₁ , R ₂ , R ₃ and R ₄ are preferably the same or different C ₁ -C ₅ lower alkyl groups or phenyl groups, and m and n are preferably 10 or more. Is an integer from １００100, and R ₅ and R ₆ are preferably the same or different C ₁ -C ₅ lower alkyl groups or phenyl groups.

As the compound represented by the above formula (3) or (4), commercially available products can also be used. Examples of such commercially available products include KF96 manufactured by Shin-Etsu Silicone Co., Ltd.
66, 69, KS68, 604, 607A, 602, 6
03, KM73, 73A, 73E, 72, 72A, 72
C, 72F, 82F, 70, 71, 75, 80, 83
A, 85, 89, 90, 68-1F, 68-2F (trade name) and the like.

The amount of the compound represented by the formula (3) or (4) is not particularly limited, but is preferably 0.001 to 2% by weight in the aqueous ink of the present invention.
If the compounding amount of the compound is less than 0.001% by weight, bubbles are easily generated at the time of preparing the ink, and it is difficult to remove small bubbles in the ink. If it exceeds 2% by weight, the generation of bubbles is suppressed. During printing, repelling may occur in the ink and the print quality may be degraded. More preferably, the above formula (3) or (4)
The compounding amount of the compound represented by is 0.005 to 0.5% by weight in the aqueous ink of the present invention.

As the surface tension adjusting agent, the above-mentioned silicone-based antifoaming agents and various surfactants of cationic, anionic or nonionic type can be used. Particularly, a silicone-based antifoaming agent represented by the above formula (3) or (4), an ethylene oxide compound of an alkyl phenol represented by the following formula (5), and an ethylene of an acetylene glycol represented by the following formula (6) The use of an oxide adduct is preferable in terms of suppression of bubble generation, ease of adjusting the surface tension of the ink, ink dischargeability, less bleeding, and non-uniform print density.

[0059]

Embedded image

[0060]

Embedded image

When using the above surface tension modifier, one or more of these compounds can be used.
It is desirable to add 0.005 to 15% by weight in the water-based ink of the present invention. If the amount is less than 0.005%, the above properties may not be exhibited,
If the content is more than 15% by weight, on the contrary, bleeding or uneven printing density may occur to lower the printing quality or lower the liquid stability of the ink.

Surface tension of water-based ink of the present invention (20 ° C.)
Is preferably in the range of 25 to 50 dyne / cm. If the surface tension is less than 25 dyne / cm, bleeding of ink and deterioration of printing quality may occur, and ink leakage may occur from a print head nozzle of an ink jet printer. May be too slow, causing mixing, contamination of the print head, and / or poor ink supply to the print head nozzles, which may result in poor ink ejection and poor print quality. The surface tension is more preferably 28 to 43 dyne / cm. Further, when the color tone is magenta, cyan, or yellow, it is preferably 28 to 40 dyne / cm, more preferably 28 to 40 dyne / cm.
36 dyne / cm, 28 to 28 when color tone is black
40 dyne / cm is more preferred. In order to make the surface tension of the aqueous ink of the present invention within the above range, for example, the concentration of the coloring material is adjusted, the concentration or the molecular weight of the polymer is adjusted, or a surface tension adjusting agent such as various surfactants. The surface tension of the ink is 2 when the additive is added or the wetting agent is used.
Means such as selecting one within a range of 5 to 50 dyne / cm may be used. The measurement of the surface tension is as follows.
Automatic surface tensiometer (CBVP-Z) manufactured by Kyowa Interface Science Co., Ltd.
Type).

The viscosity of the water-based ink of the present invention is 20
It is preferably 0.5 to 8 cps at C, more preferably 1 to 5 cps, and still more preferably 1 to 3 cp.
s. That is, if the viscosity is less than 0.5 cps, the bleeding of the ink becomes remarkable, and the ink leaks from the print head nozzles of the ink jet printer. Also, if it exceeds 8 cps,
The viscosity of the ink for inkjet is too high,
Since ink is not supplied to the print head, ejection failure occurs, and problems such as blurring and poor print quality occur.
It is preferable to be within the above range. In order to make the viscosity of the aqueous ink of the present invention within the above range, for example, the concentration of the coloring material is adjusted, the concentration or the molecular weight of the polymer is adjusted, various surfactants and the like, and surface tension adjusting agents and the like are used. Additives are added or the viscosity of the ink is 0.5
A means within a range of 内 8 cps may be selected, and a means for adjusting the usage amount or the like may be used. The viscosity was measured using an E-type viscometer (VISCONI manufactured by Tokyo Keiki Co., Ltd.).
(CELD) or a rotary viscometer (Viscomate VM-100) manufactured by Nikkato Tokyo Branch.

Next, a preferred method for producing the water-based ink of the present invention will be described with reference to an example in which the polyester (A) is used as the polymer. The aqueous ink of the present invention is preferably produced by so-called phase inversion emulsification described below.

In the phase inversion emulsification, the diol component represented by the above formula (1) (namely, the component (a)) and the polycarboxylic acid derivative [namely, the component (b)] are used together. Polyester (A) obtained by condensation polymerization (acid value: 3 to 100K)
OH mg / g) to the solvent together with the coloring material, a neutralizing agent is added to ionize the carboxyl groups in the polyester (A), and then water is added. Consistent with each other.

First, the polyester (A) is added to a solvent together with a coloring material. In this case, the polyester (A)
Is preferably added in an amount of 5 to 50 parts by weight based on 100 parts by weight of the solvent from the viewpoint of forming a suspension. Examples of the solvent include, but are not particularly limited to, acetone, methyl ethyl ketone, diethyl ketone, dipropyl ketone, methyl isobutyl ketone, ketone solvents such as methyl isopropyl ketone, and ether solvents such as tetrahydrofuran. Of these, methyl ethyl ketone and tetrahydrofuran are preferably used.

Next, a neutralizing agent is added to a mixture of the polyester (A), the coloring material, and the solvent. The amount of the neutralizing agent used is such that the above formula (A) is satisfied.
This ionizes the carboxyl groups in the polyester (A). As the neutralizing agent, any one can be used without particular limitation as long as it can ionize a carboxyl group in the polyester (A). Such neutralizing agents include, for example, aqueous ammonia, aqueous alkaline solutions of monovalent inorganic salts such as lithium hydroxide, sodium hydroxide and potassium hydroxide, allylamine, isopropylamine, diisopropylamine, ethylamine, diethylamine,
Triethylamine, 2-ethylhexylamine, 3-ethoxypropylamine, diisobutylamine, 3-diethylaminopropylamine, tri-n-octylamine, t-butylamine, sec-butylamine, propylamine, methylaminopropylamine, dimethylaminopropylamine, n-propanolamine, butanolamine, 2-amino-4-pentanol, 2-amino-3-hexanol, 5-amino-4-octanol,
3-amino-3-methyl-2-butanol, monoethanolamine, diethanolamine, dimethylethanolamine, triethanolamine, isopropanolamine, neopentanolamine, diglycolamine, ethylenediamine, 1,3-diaminopropane, 1,2 −
Diaminopropane, 1,6-diaminohexane, 1,9
-Diaminononane, 1,12-diaminododecane, dimer fatty acid diamine, 2,2,4-trimethylhexamethylenediamine, 2,4,4-trimethylhexamethylenediamine, hexamethylenediamine, N-aminoethylpiperazine, N- Examples thereof include amines such as aminopropylpiperazine, N-aminopropyldipiperidipropane, and piperazine. In particular, it is preferable to use sodium hydroxide, potassium hydroxide, triethylamine and dimethylethanolamine as the neutralizing agent, because the resulting suspension has a smaller particle size and the suspension stability is further improved. In particular, it is more preferable to use sodium hydroxide and potassium hydroxide as the neutralizing agent because the heat resistance of the obtained suspension is improved.

After the addition of the neutralizing agent, water is added to the mixture to cause phase inversion. As a result, a suspension of the polyester (A) is formed in the aqueous phase. The amount of water to be added is 100 to 300 parts by weight per 100 parts by weight of the mixture.
It is preferably in parts by weight. In this case, it is preferable to add a compound obtained by adding the compound represented by the formula (2) to water to the mixed solution because the average particle diameter of the suspension can be reduced. In addition, the above formula (3) is added to water.
Alternatively, it is preferable to add a compound to which the compound represented by (4) has been added to the above-mentioned mixed solution, since the generation of bubbles can be suppressed and the surface tension can be adjusted. It is preferable that the amount of the compound represented by the formula (2) is 0.01 to 10% by weight in the ink finally obtained as described above. On the other hand, the amount of the compound represented by the above formula (3) or (4) is preferably such that it becomes 0.001 to 2% by weight in the ink finally obtained as described above.

After the completion of the phase inversion, the solvent is removed from the mixture by heating the system under reduced pressure, and a predetermined amount of water is removed. To obtain a suspension of polyester (A).

The preferred method of producing the aqueous ink of the present invention has been described above using the polyester (A) as an example.
Instead of using a polymer, an aqueous ink composed of a suspension of a polymer having a coloring material adsorbed thereon can be obtained. For example, instead of the polyester (A),
By using the polyester (B) or the polyester polyamide, an aqueous ink comprising a suspension of the polyester (B) or the polyester polyamide adsorbing a coloring material can be obtained. In preparing the water-based ink of the present invention, it is preferable to remove coarse particles. For example, the ink obtained as described above is filtered under pressure with a filter or treated with a centrifugal separator, and is preferably 2000 nm or more, more preferably 10 nm or more.
By removing particles having a size of 00 nm or more, more preferably 500 nm or more, an ink without clogging can be obtained.

The water-based ink of the present invention is particularly useful as an ink for ink-jet recording as described above, but as other inks, for example, a general fountain pen, a ball-point pen,
It can also be used as ink for writing instruments such as felt pens. For example, when the water-based ink of the present invention is used as an ink for inkjet recording, the water-based ink may be used as it is, or may be used by adding various additives to the water-based ink as needed.

[0072]

EXAMPLES Next, the effectiveness of the water-based ink of the present invention will be illustrated by examples. However, it goes without saying that the present invention is not limited to such an embodiment.

Example 1 Polyoxypropylene (2,2) -2,2-bis (4-
(Hydroxyphenyl) 1,050 g of propane, 350 g of maleic acid, and 1.5 g of hydroquinone were placed in a glass two-liter four-necked flask, and a thermometer, a stainless steel stirring rod, a falling condenser, and a nitrogen inlet tube were attached thereto. The reaction was carried out while stirring at 210 ° C. under a nitrogen stream in a mantle heater. The degree of polymerization was monitored from the softening point according to ASTM E28-67, and the reaction was terminated when the softening point reached 93 ° C. Obtained polyester [Polyester (A)]
Is a pale yellow solid and has a Tg by DSC of 56.5 ° C.
Met. Further, the acid value of the polyester based on JIS K 0070 was 31.2 KOH mg / g, and the number average molecular weight (in terms of polystyrene by gel permeation chromatography) was 3,100. Next, 150 g of the above polyester, 50 g of an oil-soluble dye (manufactured by Orient Chemical Co., Ltd., OIL BLACK 860) and 500 g of tetrahydrofuran were put into a separable flask, and N was filled in the flask.
After _{disubstituted} was stirred to completely dissolve in methyl ethyl ketone the polyester and oily dyes. Subsequently, 8.18 g of dimethylethanolamine [1.1 times of F (x)]
Was added to ionize the carboxyl groups in the polyester. Further, Kao Corporation's Demol N (dispersant, HL
B value 8.51) 960 g of ion-exchanged water containing 3 g was dropped and stirred, and then heated to 40 ° C. under reduced pressure to remove tetrahydrofuran, and a suspension of polyester to which the dye was adsorbed (average particle size: 20 nm) 20% by weight
A water-based ink was obtained.

[Example 2] In place of maleic acid in Example 1, 2: 1 of itaconic acid and trimellitic anhydride was used.
A polyester [polyester (A)] was obtained in the same manner as in Example 1 except that the mixture was used (acid value;
0KOHmg / g, Tg; 54.8 ° C, number average molecular weight 3
400). Using this polyester, a dye (manufactured by Orient Chemical Co., Ltd.) was prepared in the same manner as in Example 1 except that 12.50 g of triethylamine (1.4 times F (x)) was used instead of dimethylethanolamine as a neutralizing amine. , OIL SCARLET 308) was adsorbed to obtain a 20% by weight aqueous ink of a polyester suspension (average particle size: 70 nm).

Example 3 Kao Corporation in Example 1
960 g of ion-exchanged water containing 3 g of Demol N (Dispersant, HLB value 8.51) manufactured by Shin-Etsu Silicone Co., Ltd.
A dye (Oriental Chemical Co., Ltd., O.D.
A 15% by weight aqueous ink of a polyester suspension (average particle size: 30 nm) to which 45 g of IL PINK 312 was adsorbed was obtained.

Example 4 Polyoxypropylene (2,2) -2,2-bis (4-
Hydroxyphenyl) propane 1050 g, dimer acid (unidim 22,
Union cap) 100 g, fumaric acid 260 g,
115 g of trimellitic anhydride, 1.5 g of hydroquinone
Was placed in a 2 liter glass four-necked flask, and a thermometer, a stainless steel stirring rod, a falling condenser, and a nitrogen inlet tube were attached thereto. The reaction was carried out while stirring at 210 ° C. under a nitrogen stream in a mantle heater. The degree of polymerization was monitored from the softening point according to ASTME 28-67, and the reaction was terminated when the softening point reached 105 ° C. The obtained polyester [Polyester (B)] was a pale yellow solid, and had a Tg of 52.0 ° C by DSC.
Further, the acid value of the polyester based on JIS K0070 was 37.1 KOH mg / g, and the number average molecular weight (in terms of polystyrene by gel permeation chromatography) was 3,500. Next, the polyester 15
0 g, oil-soluble dye (Olyl Chemical, OILYell)
ow 129) 40 g, and methyl ethyl ketone 500
g was placed in a separable flask, the inside of the flask was replaced with N ₂ , and the mixture was stirred to completely dissolve the polyester and the oil-soluble dye in methyl ethyl ketone. Subsequently, 4.37 g of sodium hydroxide [1.1 times of F (x)] was added to ionize the carboxyl groups in the polyester. Further, 960 g of ion-exchanged water was dropped and stirred, and then heated to 40 ° C. under reduced pressure to remove methyl ethyl ketone, thereby obtaining a 20% by weight aqueous ink of a dye-adsorbed polyester suspension (average particle size: 40 nm). Was.

Example 5 Instead of 960 g of ion-exchanged water in Example 4, ion-exchanged water 9 containing 3 g of Demol N (dispersant, HLB value 8.51) manufactured by Kao Corporation.
A dye (BASF Neopem Yellow 075) 40 was prepared in the same manner as in Example 4 except that 60 g was used.
Thus, a 20% by weight aqueous ink of a polyester suspension (average particle size: 10 nm) to which g was adsorbed was obtained.

Example 6 Polyoxypropylene (2,2) -2,2-bis (4-
(Hydroxyphenyl) 1050 g of propane, 250 g of fumaric acid, 115 g of trimellitic anhydride, 40 g of 6-aminocaproic acid, and 1.5 g of hydroquinone were placed in a glass 2-liter four-necked flask, and a thermometer, a stainless steel stirring rod, and a falling condenser were added. And a nitrogen inlet tube was attached thereto. The reaction was carried out while stirring at 220 ° C. under a nitrogen stream in a mantle heater. The degree of polymerization was monitored from the softening point according to ASTM E28-67, and the reaction was terminated when the softening point reached 108 ° C. The obtained polyester polyamide was a pale yellow solid and had a Tg of 55.6 ° C. by DSC. The acid value of the polyester polyamide based on JIS K 0070 was 38.5 KOH mg / g, and the number average molecular weight (in terms of polystyrene by gel permeation chromatography) was 3,200. Next, 150 g of the above polyester polyamide, 40 g of an oil-soluble dye (manufactured by Orient Chemical Co., VALIFAST BLUE 2606), and 500 g of methyl ethyl ketone were put into a separable flask, and the inside of the flask was replaced with N _2, followed by stirring to remove the polyester polyamide and the oil dye. Completely dissolved in methyl ethyl ketone. Subsequently, triethylamine 14.58
g [1.4 times F (x)] was added to ionize the carboxyl groups in the polyester polyamide. Further, after 960 g of ion-exchanged water is added dropwise and stirred, 4
By heating to 0 ° C. to remove methyl ethyl ketone, a 20% by weight aqueous ink of a polyester polyamide suspension (average particle size: 60 nm) to which the dye was adsorbed was obtained.

[Example 7] Instead of 960 g of ion-exchanged water in Example 6, ion-exchanged water 9 containing 3 g of Demol N (dispersant, HLB value 8.51) manufactured by Kao Corporation.
A polyester polyamide suspension (average particle diameter; 60 g) to which a pigment (manufactured by Mitsubishi Chemical Corporation, carbon black MA-100) was adsorbed by the same operation as in Example 9.
50 nm) of a 20% by weight aqueous ink.

Example 8 85 g of water-based ink of the polyester suspension obtained in Example 1 2 g of ethanolamine 10 g of diethylene glycol 2.5 g of glycerin 0.5 g of acetylenol EL Obtained by mixing the above components. The resulting dispersion was filtered through a 5-micron filter to remove dust and coarse particles to obtain an inkjet ink. The surface tension, viscosity and average particle size of the suspension of the obtained ink-jet ink at 20 ° C. were measured by the following methods. Table 1 shows the results. Using this ink, a commercially available micro bubble jet printer manufactured by Canon (model number BJ-1)
0VL), ink ejection amount, print density, bleed,
Fixing properties, water resistance and anti-clogging properties were evaluated by the following methods. Table 1 shows the results.

<Surface Tension> The surface tension of the ink at 20 ° C. was measured using an automatic surface tensiometer CBVP-Z (trade name) manufactured by Kyowa Interface Science Co., Ltd. <Viscosity> E type viscometer VISCON manufactured by Tokyo Keiki Co., Ltd.
IC ELD (trade name) or NIKKATO Tokyo branch office rotary viscometer Viscomate VM-100
(Trade name), the viscosity of the ink at 20 ° C. was measured. <Average particle diameter of suspension> COULTER Mo
The average particle diameter of the suspension was measured using del N4SD (trade name). In addition, electron microscopes (TEM, S
EM), the particles were directly observed, the particle diameter was measured, and the average particle diameter was calculated.

<Ink Discharge Amount> Solid printing was performed using recycled paper for PPC [manufactured by Nippon Kaishi Paper Co., Ltd.].
Measure the weight of the ink cartridge before and after printing,
The ink ejection amount was calculated from the change amount. <Print Density> Printing was carried out using solid paper using recycled paper for PPC [manufactured by Nippon Kaishi Paper Co., Ltd.], allowed to dry naturally in a room for 24 hours, and then measured its optical density using a Macbeth densitometer R.
D918 (manufactured by Macbeth). <Bleeding> Recycled paper for PPC [manufactured by Nippon Kaishi Paper Co., Ltd.]
After printing an alphanumeric character and leaving it for one hour or more, the sharpness of the character and the degree of mustache-like bleeding generated from the character were evaluated with a microscope and visually. ：: Characters are sharp and have no bleeding blemishes Δ: Characters are not sharp and bleeding occurs a little ×: Characters are not sharp and there are many bleeding <Fixing property> OHP sheet exclusively for inkjet (MJOH)
PSIN Epson), fixed with an eraser (width 18.5 mm) at an inclination of 45 °, put a load of 1 kg on it, and rubbed it back and forth five times on the solid printing surface. Observed visually. ：: No scratches or peeling on the printing surface △: Scratches or peeling on the printing surface ×: Occurring on the printing surface <Water resistance> Recycled paper for PPC [manufactured by Nippon Kaishi Paper Co., Ltd.]
After solid printing, and left for 1 hour or more, it was dipped vertically in still water for 10 seconds and pulled up vertically. After air drying in a room, the optical density of the white portion where no printing was performed was measured with a Macbeth densitometer RD918 (manufactured by Macbeth). <Clogging prevention> After printing alphanumeric characters continuously for 10 minutes with a commercially available Canon micro bubble jet printer (model number BJ-10VL), stop the printer,
It was left for 2 weeks in an environment of 40 ° C. and 25% RH without capping. After the standing, alphanumeric characters were printed again, and the number of clogging recovery operations required until the same printing as before the standing was obtained was examined. ：: Printing equivalent to the initial state is possible with 0 to 2 recovery operations. Δ: Printing equivalent to the initial period is possible with 3 to 5 recovery operations. ×: Printing equivalent to the initial state is not possible even after 6 or more recovery operations. Possible

Examples 9 to 14 Instead of the aqueous ink of the polyester suspension obtained in Example 1, the aqueous ink of the polyester suspension obtained in Examples 2 to 5 and the aqueous ink of the polyester suspension obtained in Examples 6 and 7 were used. An ink for inkjet recording was obtained in the same manner as in Example 8, except that the obtained aqueous suspension of polyester polyamide was used. Example 8 using the obtained ink
The same evaluation was made. Table 1 shows the results.

Comparative Example 1 An ink was obtained from the following formulation using a water-soluble dye commonly used in ink jet recording inks.・ C. I. Acid Yellow 4 g ・ Ethanolamine 2 g ・ Diethylene glycol 10 g ・ Glycerin 2.5 g ・ Pure water 81 g ・ Acetyleneol EL 0.5 g That is, the above components were mixed for 12 hours using a ball mill, and the obtained dispersion was filtered with a 5 μm filter. To remove dust and coarse particles to obtain an ink. The same evaluation as in Example 8 was performed using the obtained ink. Table 1 shows the results.

Comparative Example 2 A pigment ink was manufactured under the following conditions, and the same evaluation as in Example 8 was performed. (Preparation of pigment dispersion) ・ Styrene-acrylic acid copolymer 3 parts by weight ・ Triethanolamine 7 parts by weight ・ Ion-exchanged water 75 parts by weight That is, the above components are mixed and heated to about 70 ° C. to remove the resin component. Completely dissolved. 15 parts by weight of a pigment (phthalocyanine blue) was added to this aqueous solution, and a dispersion treatment was performed under the following conditions. Dispersing machine; Sand mill (manufactured by Yasukawa Seisakusho) Grinding media: Glass beads (1.7 mm diameter) Filling rate of media: 1.5 times (weight) Dispersion time: 2 hours After dispersion, remove the glass beads and use a 5 micron membrane filter. The pigment dispersion liquid (average particle diameter: 150 nm) was obtained by removing coarse particles and dust. (Manufacture of ink)-50 parts by weight of the above dispersion-2.5 parts by weight of glycerin-10 parts by weight of diethylene glycol-2 parts by weight of polyethylene glycol (PEG300)-0.5 part by weight of acetylenol EL-35 parts by weight of ion-exchanged water

[0086]

[Table 1]

As is evident from the results shown in Table 1, the water-based ink of the present invention in which the coloring material is adsorbed on the suspension of the specific polymer has the conventional formulation (Comparative Example 1).
And 2), the ink ejection amount, print density, blur,
It can be seen that all of the fixing property, water resistance, clogging prevention property and the like are further improved.

[0088]

According to the water-based ink of the present invention, bleeding of the ink is prevented, and the water resistance and fixability on a printing material are improved. In addition, by performing the above adsorption by phase inversion emulsification,
The color material can be easily and efficiently adsorbed, the bleeding of the ink is further prevented, and the water resistance and the fixing property are further improved. The water-based ink is particularly useful as an ink for ink-jet recording, and can also be used as ink for writing implements such as general fountain pens, ball-point pens, and felt-tip pens.

Claims (4)

[Claims] 1. An aqueous ink containing a suspension of a polymer to which a coloring material is adsorbed, wherein the polymer has an acid value based on JIS K 0070 of 3 to 100 KOH mg / g, and the ink has the following formula (A) A water-based ink prepared using a neutralizing agent in an amount satisfying the above condition. (Equation 1) 2. The aqueous ink according to claim 1, wherein the glass transition point of the polymer is 20 ° C. or higher. 3. The aqueous ink according to claim 1, wherein the polymer contains a unit derived from a diol component represented by the following formula (1) in the polymer chain. Embedded image 4. An ink for ink-jet recording, comprising the water-based ink according to claim 1.