JP2002167533A - Aqueous ink composition for ink-jet recording - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an aqueous ink composition for ink-jet recording having a good jetting responsibility and jetting stability without causing clogging due to ink drying at a nozzle tip, and an excellent dispersion stability, and capable of obtaining a uniform image in a high concentration with high resolution without oozing. SOLUTION: This aqueous ink composition for ink-jet recording comprises water, a colorant and an auxiliary, and the auxiliary comprising a specified weight ratio of a triol, glycol, and a condensation product of a triol with an alkylene oxide, having a specific structure represented by formula (1) (wherein, R1 is H or a 1-4C alkyl group; R2 is a 1-4C alkyl group; a+b+c=3-100), and the colorant being particularly a pigment, and a dispersant of the pigment being an anionic polymer having a weight-average molecular weight of 3,000-50,000 when exhibiting a remarkable effect.

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 used for a recording method using an ink jet system.

[0002]

2. Description of the Related Art The principle of the ink jet recording system is to discharge a liquid or a molten solid ink from a nozzle, a slit, a porous film, or the like, and perform recording directly on a recording medium. An ink discharge method includes an electric field control method for discharging ink using electrostatic attraction; a pressure pulse method for discharging ink using the vibration pressure of a piezo element; forming and growing bubbles by high heat. A thermal jet method in which ink is ejected by using the generated pressure; pressure is applied by a pump after the nozzle, and at the same time, high frequency vibration is applied by a piezo element to form particles of the ink, and then charges are applied to the ink droplets by a charging electrode. And a charge control method for controlling ink droplets charged by the control electrode;
Various ink jet recording methods, such as a spark jet method, in which a spark is generated in ink under a high voltage applied state and the ink is ejected by its explosive force, have been proposed. With these methods, an extremely high-definition image can be obtained. it can.

The characteristics required for ink used for ink-jet recording include (1) obtaining a high-resolution, high-density uniform image without bleeding on a recording medium, and (2) drying the ink at the nozzle tip. (3) good ink drying properties on the recording medium, (4) good image fastness, (5) good image stability, Good long-term storage stability, and the like. In addition, personal use and O
The on-demand type ink-jet method used for application A is inferior in terms of printing speed as compared with a competing electrophotographic laser printer or the like, and (6) high-speed response in performing high-speed printing It is important that the ink is excellent.

[0004] As the ink used in the ink jet recording system, an aqueous ink is mainly used in terms of odor and safety. Conventionally, various water-soluble dyes are dissolved in water or a mixed solvent of water and a water-soluble organic solvent. Dye-soluble inks to which various additives have been added as necessary have been used.

[0005] Dye-dissolved inks are excellent in color reproducibility and high in color saturation, and can provide good images. However, the water resistance of the images is poor and image migration occurs due to adhesion of water. In addition, since light resistance is low, there is a disadvantage that image fading is remarkable. These problems can be solved by using a water-insoluble pigment instead of the dye as the coloring agent. Generally, pigments are superior to dyes in particular in water resistance, light resistance, heat stability, and oxidation stability, but have new problems. For example, since pigments do not dissolve in the ink composition, they need to be dispersed, and maintaining a uniform dispersion state over a long period of time is a very important problem. Further, when the ink dries at the nozzle tip, the pigment may aggregate, and unlike the dye, it does not dissolve in the ink composition, which may cause nozzle clogging.

In order to solve these problems, use of a dispersant for uniformly and stably dispersing the pigment in the ink composition, or aqueous solution for the purpose of keeping the ink dry to prevent the ink from drying. Organic solvents are used. However, although the use of a dispersant is effective in dispersing the pigment in the ink composition, the surface tension of the ink is unnecessarily reduced, and feathering occurs when inkjet recording is performed on a recording medium such as paper. At the same time, the occurrence of bleeding becomes remarkable, and at the same time, the print density is lowered. Further, there is a problem that an image defect such as printing omission due to bubbles easily occurs. Further, use of a water-soluble organic solvent more than necessary causes a problem that the viscosity of the ink composition is increased, and the stability at the time of continuous ejection of the ink is reduced.

Therefore, in a pigment-dispersed aqueous ink composition, optimization is generally performed by selecting a dispersant and a solvent system in the ink composition and adjusting the composition while balancing the characteristics. Has been done.

[0008] Japanese Patent No. 2660155 describes an ink-jet ink composition containing at least 4.5% of a polyol / alkylene oxide condensate and a cyclic amide derivative as co-solvents. Here, Liponic EG-1 is used as a polyol / alkylene oxide condensate.
It is taught that a combination of (alkylene oxide condensate of glycerin) and N-methylpyrrolidone is useful as a cyclic amide compound.

Japanese Patent No. 2,714,485 describes an ink composition for ink jet which uses a polyol / alkylene oxide condensate of 4.5% or more as an auxiliary solvent and a block polymer as a pigment dispersant.
Here, it is taught that Liponic EG-1 (alkylene oxide condensate of glycerin) is useful.

JP-A-11-349871 discloses an ink composition for inkjet using a C2-C8 terminal alkanediol as an auxiliary solvent and a substance selected from polyethylene glycols and a polyol / polyalkylene oxide condensate. Have been. Here, it is taught that it is useful to use an alkanediol and a polyethylene glycol or an alkanediol and a glycerin / polyalkylene oxide condensate as auxiliary solvents and to use a specific polymer containing a siloxyl substituent as a dispersant.

As described above, in order to satisfy the above-mentioned various properties required for the aqueous ink for ink-jet recording, particularly in the case of a pigment-dispersed ink, selection of a dispersant for the pigment and an auxiliary solvent other than water, The composition of has been studied. However, when other soluble materials are added to water, which is the main component of the water-based ink, a decrease in surface tension is inevitable. Therefore, especially when printed on paper, an image having feathering causes bleeding. Will be.

[0012]

The problem to be solved by the present invention is that a high-resolution, high-density uniform image without bleeding is obtained, and clogging due to ink drying does not occur at the nozzle tip. Another object of the present invention is to provide a water-based ink for ink-jet recording containing a coloring material having good ejection responsiveness and ejection stability and excellent dispersion stability.

[0013]

According to the present invention, there is provided an aqueous ink composition for ink-jet recording comprising at least water, a colorant and an auxiliary solvent, wherein the auxiliary solvent comprises (1) a triol. , (2) a glycol and (3) a condensation product of a triol / alkylene oxide having a molecular weight of 300 or more having the formula:

Embedded image (Wherein, R ¹ is H, an alkyl group of C1 to C4, and R ² is C1
-C4 alkyl group, a + b + c is 3-100)
And (1) is 1 to 20%, (2) is 1 to 10%, and (3) is 0.5 to 4 with respect to the total mass of the ink composition.
% And a surface tension of 35 mN / m or more.

By using the auxiliary solvent having the composition described above in the addition amount within the range described above, the clogging due to drying of the ink at the nozzle tip can be prevented without deteriorating the high-speed ejection property due to the increase in viscosity due to the addition of the auxiliary solvent. Occurrence can be prevented. Furthermore, since the decrease in surface tension due to the addition of the auxiliary solvent can be minimized, the occurrence of feathering can be prevented, and a uniform image without bleeding can be formed.

The effect of using such an auxiliary solvent is that a pigment, particularly carbon black, is used as a colorant, and a weight average molecular weight of 3,000 to 50 is used as a dispersant for the pigment.
This is particularly noticeable when an anionic polymer of 000 is used, and a decrease in surface tension due to the use of a dispersant can be suppressed. Considering the dispersing effect of the pigment, the adverse effect on the surface tension, and the increase in viscosity, the amount of the anionic polymer to be added is preferably 0.5 to 20% by weight. As the anionic polymer, a weight average molecular weight of 5000 to 2 is particularly preferable.
A styrene-acrylic copolymer of 0000 is preferable, and at least acrylic acid and methacrylic acid are contained as monomers constituting the polymer, and the weight ratio of acrylic acid to methacrylic acid is in the range of 1:10 to 10: 1. Are preferred because of their good pigment dispersibility and long-term storage stability.

As the condensation product of triol / alkylene oxide, those in which the triol is trimethylolpropane are preferable because they do not easily cause feathering due to a decrease in surface tension, and the condensation product of triol / alkylene oxide in which the alkylene oxide is ethylene oxide is more preferable. Products are more preferred.

The anionic polymer may be a graft polymer having a weight-average molecular weight of 5,000 to 20,000, particularly a polymer having a pigment dispersing function incorporated in its molecular design. For example, a styrene acrylic copolymer may be used. Examples thereof include those using a styrene copolymer macromonomer having a methacryloyl group at one end as a component thereof.

[0018]

The coloring agent used in the aqueous ink composition for ink-jet recording of the present invention includes, for example,
Carbon black, titanium black, titanium white,
Inorganic pigments such as zinc sulfide and benkara; organic pigments such as phthalocyanine pigments, monoazo pigments, disazo pigments and quinacridone pigments; disperse dyes, hollow fine particles, and resin fine particles colored with dyes or pigments.

As the black pigment, furnace black,
Carbon black pigments such as lamp black, acetylene black and channel black are preferred. Such carbon black pigments include, for example, Raven 7000, Raven 5750, Raven 5250, Raven 5000 Ultra (UL)
TRA) II, Raven 3500, Raven 250
0 Ultra, Raven 2000, Raven 150
0, Raven 1255, Raven 1250, Raven 1200, Raven 1190 Ultra II, Raven 1170, Raven 1080 Ultra, Raven 1060 Ultra, Raven 790 Ultra, Raven 780 Ultra, Raven 760
Ultra (above, manufactured by Columbian Carbon Co., Ltd.), Regal 400R, Legal 330R,
Regal 660R, Mogul L, Monarch 700, Monarch
arch) 800, Monarch 880, Monarch 90
0, Monarch 1000, Monarch 1100, Monarch 1300, Monarch 1400 (all manufactured by Cabot), Color Black FW1, Color Black
FW2, color black FW2V, color black 18, color black FW200, color black S150, color black S160, color
Black S170, Printtex
x) 35, Printex U, Printex V, Printex 140U, Printex 140V, Special Black 6, Special Black 5, Special Black 4A, Special Black 4 (all manufactured by Degussa), No. 25, no. 33, N
o. 40, no. 45, no. 45L, No.
47, no. 52, no. 900, No. 96
0, No. 2300, MCF-88, MA600, M
A7, MA8, and MA100 (all manufactured by Mitsubishi Chemical Corporation).

Among these carbon blacks, those having a primary particle diameter of 10 to 30 nm, particularly 15 to 30 nm are preferred. When an aqueous dispersion using carbon black having a primary particle diameter of less than 10 nm is applied to an ink for ink-jet recording, the viscosity of the ink tends to be high, and the ejection property of the ink tends to be deteriorated.
When an aqueous dispersion using carbon black in excess of the above is applied to an ink jet recording ink, the image density tends to be insufficient, which is not preferable.

The volatile content of carbon black is 1 to
Those in the range of 8% are preferred, and those in the range of 1-6% are particularly preferred. When carbon black having a volatile content of less than 1% is used, the wettability of the carbon black with water tends to be poor and dispersibility tends to be poor. When carbon black having a volatile content exceeding 6% is used, carbon black is used. Due to the repulsion between the acidic functional groups on the surface and the dispersant,
It is not preferable because the dispersant polymer is less likely to be adsorbed and tends to have poor stability.

Further, the DBP oil absorption of carbon black is preferably in the range of 40 to 80 ml / 100 g, particularly preferably in the range of 45 to 70 ml / 100 g. When carbon black having a DBP oil absorption of less than 40 ml / 100 g is used, the dispersibility is poor, and 80 ml / 1
When an aqueous dispersion using carbon black exceeding 00 g is applied to an ink jet recording ink, the viscosity of the ink increases, and the ink ejection properties tend to deteriorate, which is not preferable.

The cyan pigment is not particularly restricted but includes, for example, C.I. I. Pigment Blue
1, C.I. I. Pigment Blue 2, C.I. I. Pigment Blue 3, C.I. I. Pigment Blue 15,
C. I. Pigment Blue 15: 1, C.I. I. Pigment Blue 15: 3, C.I. I. Pigment blue 15:34, C.I. I. Pigment Blue 16,
C. I. Pigment Blue 22, C.I. I. Pigment Blue 60, and the like.

The magenta pigment is not particularly limited. I. Pigment Red
5, C.I. I. Pigment Red 7, C.I. I. Pigment Red 12, C.I. I. Pigment Red 4
8, C.I. I. Pigment Red 48: 1, C.I. I.
Pigment Red 57, C.I. I. Pigment Red 112, C.I. I. Pigment Red 122,
C. I. Pigment Red 123, C.I. I. Pigment Red 146, C.I. I. Pigment Red
168, C.I. I. Pigment Red 184, C.I.
I. Pigment Red 202, and the like.

The yellow pigment is not particularly limited. For example, C.I. I. Pigment Yellow
1, C.I. I. Pigment Yellow 2, C.I. I. Pigment Yellow 3, C.I. I. Pigment Yellow 12, C.I. I. Pigment Yellow 13, C.I. I.
Pigment Yellow 14, C.I. I. Pigment Yellow 16, C.I. I. Pigment Yellow 17,
C. I. Pigment Yellow 73, C.I. I. Pigment Yellow 74, C.I. I. Pigment Yellow 7
5, C.I. I. Pigment Yellow 83, C.I. I. Pigment Yellow 93, C.I. I. Pigment Yellow 95, C.I. I. Pigment Yellow 97, C.I.
I. Pigment Yellow 98, C.I. I. Pigment Yellow 114, C.I. I. Pigment Yellow 1
28, C.I. I. Pigment Yellow 129, C.I.
I. Pigment Yellow 151, C.I. I. Pigment Yellow 154, and the like.

Further, as a coloring material, these black,
In addition to the three primary color pigments of cyan, magenta and yellow, red,
Specific color pigments such as green, blue, brown, and white, metallic luster pigments such as gold and silver, colorless extender pigments, and plastic pigments can be used. The pigment is not limited to these, and a newly synthesized pigment can be used.

The amount of the colorant used in the aqueous dispersion of the present invention is 0.5 to 15 based on the total weight of the aqueous dispersion.
% By weight, with a range of 0.5 to 10% by weight being particularly preferred. When the amount of the coloring material used is less than 0.5% by weight, coloring is insufficient, and particularly when the aqueous dispersion of the present invention is used as an aqueous ink for inkjet recording, a sufficient image density tends not to be obtained. Is not preferred. When the use amount of the coloring material is more than 15% by weight,
The viscosity of the aqueous dispersion tends to be too high,
Further, the dispersion stability tends to be deteriorated. In particular, when the aqueous dispersion of the present invention is used as an aqueous ink for inkjet recording, the ink ejection property tends to deteriorate, which is not preferable.

The anionic polymer used in the aqueous ink for ink-jet recording of the present invention functions as a dispersant for a colorant and has a weight average molecular weight of 3,000 to 50,000.
5,000 to 20,000.
A range of 00 is particularly preferred. When the weight average molecular weight of the anionic polymer is less than 3,000, the molecular weight is too low and the dispersion stability tends to be inferior. When the weight average molecular weight of the dispersant exceeds 50,000, the viscosity becomes high. This is not preferable because the ink ejection property tends to decrease in ink jet recording and the print density tends to decrease. The weight average molecular weight in the present invention is GPC
(Gel / penetration / chromatography) method.

Specific examples of the anionic polymer include a polymer obtained by reacting a reactive monomer having an anionic group such as a carboxyl group alone or with a reactive monomer having no anionic group in the molecule. For example, styrene- (meth) acrylic acid copolymer, (meth) acrylic acid-alkyl (meth) acrylate copolymer, styrene- (meth) acrylic acid-alkyl (meth) acrylate copolymer , Styrene-α-methylstyrene- (meth) acrylic acid copolymer, styrene-α-methylstyrene- (meth)
Acrylic acid-based resins such as acrylic acid- (meth) acrylic acid alkyl ester copolymer, vinylnaphthalene- (meth) acrylic acid copolymer, diisobutylene-maleic acid copolymer, styrene-maleic acid copolymer, Maleic acid resins such as maleic acid-maleic anhydride copolymer and vinylnaphthalene-maleic acid copolymer can be mentioned, and these can be used alone or in combination of two or more.

The acid value of the anionic polymer used in the aqueous dispersion of the present invention is preferably in the range of 50 to 300 mgKOH / g, and is preferably in the range of 80 to 250 mgKOH / g.
It is particularly preferable that the ratio is within the range. The acid value of the dispersant is 50
When it is less than mgKOH / g, the solubility in an aqueous medium tends to decrease, the dispersion stability of the coloring material in the aqueous medium tends to be poor, and the acid value of the dispersant tends to be 300 mgKOH / g.
When the value exceeds, the water solubility becomes too high, and when used as an aqueous ink for inkjet recording, it tends to cause deterioration of water resistance and poor ejection of the ink, which is not preferable.

The anionic polymer used in the aqueous ink composition of the present invention has an acid value of at least 80.
% Neutralized. Neutralization can be carried out using various basic substances. For example, alkali metal hydroxides such as sodium hydroxide and organic amines such as 2-dimethylaminoethanol, N-methyldiethanolamine and triethanolamine can be used.

With regard to the form of the anionic polymer for dispersing the pigment of the present invention, in addition to the usual random polymer,
It may be a structured polymer that can be designed to have a required function as a dispersant, and a graft polymer is particularly useful as a structured polymer because of its ease of production. For example, regarding the production of a graft polymer, according to the macromonomer method disclosed in “Polymer”, Vol. 31, p. 988 (1982), the graft polymer is produced by a method which is no different from the conventional production of a random polymer. Can be synthesized. Other structured polymers may be block polymers, but the living polymerization method is necessary, and new methods such as the GTP method have been developed, but the types of raw materials that can be used are limited. There are many problems such as the need to use high-purity raw materials.

The aqueous ink composition for ink jet recording of the present invention contains an auxiliary solvent. The purpose of this auxiliary solvent addition is to adjust the viscosity of the aqueous ink composition used to an appropriate value in order to stably generate ink droplets ejected in ink jet recording, and to adjust the viscosity of the ink at the nozzle tip. The purpose of the present invention is to prevent the occurrence of clogging due to dryness of the dried product.

Further, the surface tension of the aqueous ink composition is affected by the type of the auxiliary solvent or the composition of the auxiliary solvent. Just as the viscosity of the ink affects the mechanism of ink droplet generation in inkjet recording, the ink surface tension also has an effect. The surface tension of the ink is
Since it greatly affects the feathering characteristics of the ink recorded on the recording medium, it greatly affects the occurrence of image bleeding. Therefore, in order to obtain the characteristics required for the aqueous ink composition for inkjet recording, by selecting and combining appropriate auxiliary solvent types, stable ink droplet formation was possible, and continuous ejection was performed. In this case, the ink ejection is stable, and excellent ink can be obtained in which the recorded ink does not bleed on the recording medium. For that purpose, it is necessary to prepare an aqueous ink composition having appropriate viscosity and high surface tension.

The aqueous ink composition for ink jet recording of the present invention comprises (1) triol and (2)
A condensation product of glycol and (3) a triol / alkylene oxide having the formula:

Embedded image (Wherein R1 is H, a C1-C4 alkyl group, R2 is C
1 to C4 alkyl groups, a + b + c is 3 to 100).

The amount of these auxiliary solvents is preferably in the range of 5 to 30% based on the total amount of the ink composition.
A range of ２５25% is particularly preferred. 5% of total amount of auxiliary solvent
If the amount is smaller, the moisturizing effect does not sufficiently appear, so that the ink easily dries at the nozzle tip, nozzle clogging occurs, and a uniform good image cannot be obtained. On the other hand, if the total amount of the auxiliary solvent exceeds 30%, the viscosity of the ink significantly increases, which hinders the supply of the ink in the ink recording head and may cause an ink ejection failure.

Glycerin, triol (1)
Examples include trimethylolpropane, 1,2,4-butanetriol, and 1,2,6-hexanetriol. The ratio of these inks to the total amount is preferably in the range of 1 to 20%, and particularly preferably in the range of 1 to 10%. If it is less than 1%, the ink tends to dry at the nozzle tip, causing nozzle clogging and failing to obtain a uniform good image. On the other hand, if it is more than 20%, the viscosity of the ink becomes too high, and the ink ejection direction tends to be abnormal, so that a uniform image tends not to be obtained.

Examples of the glycol (2) include diethylene glycol, triethylene glycol and tetraethylene glycol. The proportion of these inks in the total amount is preferably in the range of 1 to 30%, particularly preferably in the range of 5 to 20%. If the amount is less than 1%, the ink composition tends to have poor pigment dispersibility. If the amount is more than 30%, the viscosity of the ink composition tends to increase too much, and an abnormal ink ejection direction tends to occur. As the triol / alkylene oxide condensation product (3), triol is particularly preferable because trimethylolpropane does not lower the surface tension of the ink composition. The amount of this compound in the whole ink composition is preferably in the range of 0.5 to 4%, particularly preferably in the range of 1 to 4%. If it is less than 0.5%, uniform image density tends not to be obtained, and if it is more than 4%, high-speed ejection tends to deteriorate.

The present invention provides a water-based ink composition for ink jet recording which suppresses feathering phenomenon and does not cause bleeding when printing on plain paper, and which exhibits a high surface tension. That is, a penetrant can be added to the aqueous ink composition for ink jet recording of the present invention in order to accelerate the penetration drying which is the largest drying phenomenon in the ink jet recording method. As such a penetrating agent, known and commonly used ones can be used, and examples thereof include lower alcohols such as ethanol and isopropyl alcohol, glycol ethers such as diethylene glycol-n-butyl ether, and water-soluble organic solvents such as propylene glycol derivatives.

The colorant contained in the aqueous ink composition for ink jet recording of the present invention is 3,000 to 50,000.
Is dispersed in an aqueous medium by the effect of an anionic polymer as a dispersant. In order to enhance the dispersion stability, that is, to suppress aggregation and sedimentation of the colorant in a long-term storage, it is further known. A suitable surfactant can be added. In order to accelerate the penetration drying, a surfactant can be added for the purpose of adjusting the surface tension of the ink composition. Although the addition of a surfactant tends to lower the surface tension of the ink and induce bleeding of the image, the aqueous ink composition for ink jet recording of the present invention has a high surface tension and the dispersion stability of the colorant. Regarding the enhancement of the water-repellent property or the speed of ink penetration drying, even if a sufficient amount of a surfactant is added, the decrease in the surface tension is small and an image with very little bleeding can be obtained.

When the surfactant is added, the amount added is preferably in the range of 0.001 to 1% by weight, more preferably 0.001 to 0.5% by weight, based on the total weight of the ink. The range of 0.01 to 0.2% by weight is more preferable.
Surfactants that can be added to the aqueous ink for inkjet recording of the present invention are not particularly limited, and various anionic surfactants, nonionic surfactants, cationic surfactants, amphoteric surfactants, And so on,
Among these, anionic surfactants and nonionic surfactants are particularly preferred.

Examples of the anionic surfactant include, for example,
Alkyl benzene sulfonate, alkyl phenyl sulfonate, alkyl naphthalene sulfonate, higher fatty acid salt, higher fatty acid ester sulfate, higher fatty acid ester sulfonate, higher alcohol ether sulfate and sulfonate, higher Alkyl sulfosuccinate, polyoxyethylene alkyl ether carboxylate, polyoxyethylene alkyl ether sulfate, alkyl phosphate, polyoxyethylene alkyl ether phosphate, etc., dodecylbenzene sulfonate, isopropyl naphthalene sulfonic acid Salt, monobutylphenylphenol monosulfonate, monobutylbiphenylsulfonate, monobutylbiphenylsulfonate, dibutylphenylphenoldisulfonate,
And so on.

Examples of the nonionic surfactant include, for example,
Polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbitol fatty acid ester, glycerin fatty acid ester, polyoxyethylene glycerin fatty acid ester,
Polyglycerin fatty acid ester, sucrose fatty acid ester, polyoxyethylene alkylamine, polyoxyethylene fatty acid amide, alkylalkanolamide, acetylene glycol, oxyethylene adduct of acetylene glycol, polyethylene glycol polypropylene glycol block copolymer, and the like. Among them, polyoxyethylene nonyl phenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene dodecyl phenyl ether, polyoxyethylene alkyl ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, fatty acid alkylol Amide, acetylene glycol, acetylene glycol with oxyethylene Things, polyethylene glycol polypropylene glycol block copolymers are preferred.

Other surfactants include silicone surfactants such as polysiloxane oxyethylene adducts; and fluorine surfactants such as perfluoroalkyl carboxylate, perfluoroalkyl sulfonate and oxyethylene perfluoroalkyl ether. Agents; biosurfactants such as spiculisporic acid, rhamnolipid, lysolecithin, and the like can also be used. These surfactants can be used alone or in combination of two or more.

The ink composition of the present invention can be prepared, for example, according to any of the following production methods. (1) By adding a colorant to an aqueous medium containing at least water, an anionic polymer dispersant and an aqueous medium containing a base necessary for neutralization of the dispersant, and then using various stirring and dispersing devices, A method of preparing an aqueous dispersion in which a coloring material is to be dispersed, and then adding an auxiliary solvent to prepare an ink composition. (2) After preliminarily kneading the coloring material and the dispersant with two rolls, a mixer or the like, the resulting kneaded material is placed in an aqueous medium containing at least water and a base necessary for neutralizing the dispersant. A method in which an aqueous dispersion is prepared using a stirring and dispersing device, and then an auxiliary solvent is added to prepare an ink composition. (3) Methyl ethyl ketone, tetrahydrofuran (TH
After adding a coloring agent to a solution in which a dispersant is dissolved in an organic solvent compatible with water as in F), a dispersion is prepared using a stirring / dispersing device, and then the dispersant is neutralized. A method of preparing an aqueous dispersion by a phase inversion emulsification method using an aqueous medium in which a base necessary for the above is dissolved.

Examples of the stirring and dispersing apparatus include an ultrasonic homogenizer, a high-pressure homogenizer, a paint shaker, a ball mill, a roll mill, a sand mill, a sand grinder, a dyno mill, a dispermat, an SC mill, and a nanomizer. Stirring these,
The dispersing device may be used alone, or two or more kinds of devices may be combined. When the aqueous dispersion is used as an aqueous ink for inkjet recording, coarse particles may cause deterioration of image characteristics such as clogging of nozzles. , It is preferable to remove coarse particles by centrifugation or filtration.

Hereinafter, the present invention will be described in more detail with reference to Examples. In the following examples, “parts” and “%” are based on parts by weight unless otherwise specified. The prepared aqueous ink composition for inkjet recording was finally subjected to a filtration treatment using a filter having a pore size of 6 μm.

[0048]

<Example 1> (Synthesis of anionic polymer (A1)) 25 parts of styrene, 52 parts of methyl methacrylate, 10 parts of acrylic acid, 10 parts of methacrylic acid while keeping 100 parts of methyl ethyl ketone at 80 ° C under a nitrogen atmosphere. A mixture consisting of 13 parts and 6 parts of a polymerization catalyst (“V-59” manufactured by Wako Pure Chemical Industries, Ltd.) was added dropwise over 2 hours. After the addition, the reaction was continued at the same temperature for another 16 hours. In the course of the reaction, a polymerization catalyst was added as appropriate while checking the consumption of the raw materials. Thus, a methyl ethyl ketone solution (B1) containing 53% of the anionic polymer (A1) as a solid content was obtained. The polymerization average molecular weight of the obtained anionic polymer was 12,0.
The acid value was 139 mgKOH / g.

(Preparation of Aqueous Dispersion (D1)) To 100 parts of methyl ethyl ketone solution (B1), an aqueous solution consisting of 5.25 parts of sodium hydroxide and 330 parts of water was gradually added while stirring. After adding the entire amount of aqueous sodium hydroxide solution, methyl ethyl ketone was distilled off under reduced pressure to finally obtain an aqueous solution (C1) having a solid content of 20%. Next, the aqueous solution (C1) was charged with the following composition, and then subjected to a dispersion treatment using a paint conditioner to obtain an aqueous dispersion (D1). Anionic polymer (A1) 3 parts Carbon black (Mitsubishi Chemical Corporation # 960) 10 parts Diethylene glycol 20 parts Water 35 parts Zirconia beads (1.25 mm diameter) 400 parts Time 4 hours

(Preparation of Aqueous Ink Composition (E1)) After the dispersion treatment, the beads were removed, and then the aqueous dispersion (D1) was prepared.
Was added with an auxiliary solvent and water to prepare an ink composition (E1) for inkjet recording having the following composition. As a co-solvent triol / alkylene oxide condensation product, a trimethylolpropane / ethylene oxide condensate having a molecular weight of about 530 (trade name “Leocon TP53E” manufactured by Lion Corporation) was used. Anionic polymer (A1) 1.19 parts Carbon black (Mitsubishi Chemical Corporation # 960) 3.96 parts Diethylene glycol 8 parts Glycerin 8 parts Leocon TP53E 4 parts Water 74.85 parts

<Example 2> (Preparation of aqueous ink composition (E2)) An aqueous ink composition (E2) having the following composition was prepared from the aqueous dispersion (D1) in the same manner as in Example 1. Anionic polymer (A1) 1.19 parts Carbon black (Mitsubishi Chemical Corporation # 960) 3.96 parts Diethylene glycol 8 parts Glycerin 4 parts Leocon TP53E 4 parts Water 74.85 parts

Example 3 An aqueous ink composition (E) having the following composition was prepared from the aqueous dispersion (D1) in the same manner as in Example 1.
3) was prepared. Anionic polymer (A1) 1.19 parts Carbon black (Mitsubishi Chemical Corporation # 960) 3.96 parts Diethylene glycol 16 parts Glycerin 8 parts Leocon TP53E 4 parts Water 66.85 parts

Example 4 (Aqueous ink composition (E4)
Preparation) Example 1 except that a trimethylolpropane / propylene oxide condensate having a molecular weight of about 400 (trade name: "Sannicks TP-400" manufactured by Sanyo Chemical Co., Ltd.) was used as a condensation product of triol / alkylene oxide as an auxiliary solvent. In the same manner as in the above, an aqueous ink composition (E4) was prepared. Anionic polymer (A1) 1.19 parts Carbon black (Mitsubishi Chemical Corporation # 960) 3.96 parts Diethylene glycol 8 parts Glycerin 8 parts Sannicks TP-400 4 parts Water 74.85 parts

<Example 5> (Synthesis of anionic polymer (A2)) 25 parts of styrene, 25 parts of methyl methacrylate, 27 parts of butyl methacrylate, and acrylic acid, while keeping 100 parts of methyl ethyl ketone at 80 ° C under a nitrogen atmosphere. 10 parts, methacrylic acid 13
Part and polymerization catalyst (“V-59” manufactured by Wako Pure Chemical Industries, Ltd.) 4
Part of the mixture was added dropwise over 2 hours. After the completion of the dropwise addition, the reaction was continued at the same temperature for another 24 hours. In the course of the reaction, a polymerization catalyst was added as appropriate while checking the consumption of the raw materials. Thus, a methyl ethyl ketone solution (B2) containing 52% of the anionic polymer (A2) as a solid content was obtained. The polymerization average molecular weight of the obtained anionic polymer is 15, 300 and the acid value is 149 mgK.
OH / g.

(Preparation of Aqueous Dispersion (D2)) An aqueous solution consisting of 5.52 parts of sodium hydroxide and 330 parts of water was gradually added to 100 parts of the methyl ethyl ketone solution (B2) while stirring. After the entire amount of aqueous sodium hydroxide solution was added, methyl ethyl ketone was distilled off under reduced pressure to finally obtain an aqueous solution (C2) having a solid content of 21%. Next, the aqueous solution (C2) was charged with the following composition, and then dispersed using a paint conditioner to obtain an aqueous dispersion (D2). Anionic polymer (A2)
5 parts Carbon black (Mitsubishi Chemical's # 960) 10 parts Diethylene glycol 20 parts Water 35 parts Zirconia beads (1.25 mm diameter) 400 parts Time 4 hours

(Preparation of Aqueous Ink Composition (E5)) After the dispersion treatment, the beads were removed, and then the aqueous dispersion (D2) was prepared.
Was added with an auxiliary solvent and water to prepare an inkjet recording ink composition (E5) having the following composition. Anionic polymer (A2) 1.95 parts Carbon black (Mitsubishi Chemical Corporation # 960) 3.9 parts Diethylene glycol 8 parts Glycerin 8 parts Leocon TP53E 4 parts Water 74.15 parts

<Example 6> (Synthesis of anionic polymer (A3)) 50 parts of styrene, 27 parts of methyl methacrylate, 10 parts of acrylic acid, 13 parts of methacrylic acid 13 were kept in a nitrogen atmosphere at 80 ° C under 100 parts of methyl ethyl ketone. Of a polymerization catalyst (“V-59” manufactured by Wako Pure Chemical Industries, Ltd.) was added dropwise over 2 hours. After the completion of the dropwise addition, the reaction was continued at the same temperature for another 24 hours. In the course of the reaction, a polymerization catalyst was added as appropriate while checking the consumption of the raw materials. Thus, a methyl ethyl ketone solution (B3) containing 53% of the anionic polymer (A3) as a solid content was obtained. The polymerization average molecular weight of the obtained anionic polymer was 11,0.
The 00 acid value was 140 mgKOH / g.

(Preparation of Aqueous Dispersion (D3)) An aqueous solution consisting of 5.29 parts of sodium hydroxide and 330 parts of water was gradually added to 100 parts of a methyl ethyl ketone solution (B3) while stirring. After the entire amount of aqueous sodium hydroxide solution was added, methyl ethyl ketone was distilled off under reduced pressure to finally obtain an aqueous solution (C3) having a solid content of 22%. Next, the aqueous solution (C3) was charged with the following composition, and then dispersed using a paint conditioner to obtain an aqueous dispersion (D3). Anionic polymer (A3) 5 parts Carbon black (Mitsubishi Chemical Corporation # 45L) 10 parts Diethylene glycol 20 parts Water 35 parts Zirconia beads (1.25 mm diameter) 400 parts Time 4 hours

(Preparation of Aqueous Ink Composition (E6)) After the dispersion treatment, the beads were removed, and then the aqueous dispersion (D2) was prepared.
Was added with an auxiliary solvent and water to prepare an ink composition (E6) for inkjet recording having the following composition. Anionic polymer (A3) 2.07 parts Carbon black (Mitsubishi Chemical Corporation # 960) 4.14 parts Diethylene glycol 8 parts Glycerin 8 parts Leocon TP53E 4 parts Water 73.79 parts

<Example 7> (Synthesis of anionic polymer (A4)) 72 parts of styrene, 10 parts of acrylic acid, and 13 parts of methacrylic acid 13 were kept in a nitrogen atmosphere at 80 ° C under 100 parts of methyl ethyl ketone.
Part, styrene copolymer macromonomer having methacryloyl group at one end ("AS-6" manufactured by Toagosei Chemical Co., Ltd.)
5 parts and polymerization catalyst ("Perbutyl O" manufactured by NOF Corporation)
A mixture of 10 parts was added dropwise over 2 hours. After the completion of the dropwise addition, the reaction was continued at the same temperature for another 20 hours. In the course of the reaction, a polymerization catalyst was added as appropriate while checking the consumption of the raw materials.

Thus, a methyl ethyl ketone solution (B4) containing 54% of the graft polymer (A4) as a solid content was obtained by the macromonomer method. The weight average molecular weight of the obtained graft copolymer (A4) is 11,5.
00, the acid value was 149 mgKOH / g.

(Preparation of Aqueous Dispersion (D4)) An aqueous solution consisting of 5.74 parts of sodium hydroxide and 340 parts of water was added to 100 parts of the methyl ethyl ketone solution (B4) with stirring, and methyl ethyl ketone was distilled off under reduced pressure. Leave
An aqueous solution (C4) containing 19.1% solids was obtained. After the aqueous solution (C4) was charged with the following composition and dispersed using a paint conditioner, an aqueous dispersion (D4) was obtained. Anionic graft polymer (A4) 3.15 parts Carbon black (Mitsubishi Chemical Corporation # 960) 10.5 parts Diethylene glycol 20 parts Water 35 parts Zirconia beads (1.25 mm diameter) 400 parts Time 4 hours

(Preparation of Aqueous Ink Composition (E7)) An ink jet recording ink composition having the following composition was prepared in the same manner except that D7 was used in place of the aqueous dispersion (D1) of Example 1. E7) was prepared. Anionic graft polymer (A4) 1.21 parts Carbon black (# 45L manufactured by Mitsubishi Chemical Corporation) 4.02 parts Diethylene glycol 8 parts Glycerin 8 parts Leocon TP53E 4 parts Water 74.77 parts

Comparative Example 1 (Preparation of Ink Composition (E8)) From the aqueous dispersion (D1) used in Example 1, an ink composition (E8) having the following composition
8) was prepared. Anionic polymer (A1) 1.19 parts Carbon black (Mitsubishi Chemical Corporation # 960) 3.96 parts Diethylene glycol 8 parts Glycerin 8 parts Leocon TP53E 8 parts Water 70.85 parts

<Comparative Example 2> (Preparation of Ink Composition (E9)) Polypropylene glycol having a molecular weight of about 200 (trade name “SANNIX PP-”) was used in place of the trimethylolpropane / ethylene oxide adduct used in Example 1. 200 "(manufactured by Sanyo Chemical Industries, Ltd.), and an ink composition (E7) having the following composition was prepared from the aqueous dispersion (D1). Anionic polymer (A1) 1.19 parts Carbon black (Mitsubishi Chemical Corporation # 960) 3.96 parts Diethylene glycol 8 parts Glycerin 8 parts Sannicks PP-200 4 parts Water 74.85 parts

Comparative Example 3 Preparation of Ink Composition (E10) Instead of the trimethylolpropane / ethylene oxide adduct used in Example 5, a triethanolamine / propylene oxide adduct having a molecular weight of about 500 (commercially available) Name "Leocon TA470"
Using Lion Corporation), an ink composition (E10) having the following composition was prepared from the aqueous dispersion (D2). Anionic polymer (A2) 1.95 parts Carbon black (Mitsubishi Chemical Corporation # 960) 3.9 parts Diethylene glycol 8 parts Glycerin 8 parts Leocon TA470 4 parts Water 74.15 parts

<Comparative Example 4> (Preparation of Ink Composition (E11)) Instead of the trimethylolpropane / ethylene oxide condensate having a molecular weight of about 530 used in Example 6, a product having a molecular weight of about 270 (trade name “Reocon TP27E”) was used. "Lion Co., Ltd.) from the aqueous dispersion (D3) from the ink composition (E1
1) was prepared. Anionic polymer (A3) 2.07 parts Carbon black (Mitsubishi Chemical Corporation # 960) 4.14 parts Diethylene glycol 8 parts Glycerin 8 parts Leocon TP53E 4 parts Water 73.79 parts

Comparative Example 5 (Preparation of Ink Composition (E12)) An ink composition (E12) having the following composition was prepared in the same manner as in Example 1 except that trimethylolpropane / ethylene oxide condensate was not used. ) Was prepared. Anionic polymer (A1) 1.19 parts Carbon black (Mitsubishi Chemical Corporation # 960) 3.96 parts Diethylene glycol 8 parts Glycerin 8 parts Water 74.85 parts

<Evaluation Test> (Evaluation Test 1: Surface Tension) The surface tension at 25 ° C. of the obtained aqueous ink composition for ink jet recording was measured using CBVP-A3 type manufactured by Kyowa Interface Science Co., Ltd. Next, the obtained aqueous ink for ink-jet recording was applied to an ink-jet printer “NOVA JET (NOVA J
et) 700 "(manufactured by ENCAD), various ink jet recording characteristics were evaluated.

(Evaluation Test 2: Inkjet Recording Characteristics:
Print density) Printer print mode bi-directional, pass:
4. Speed: set to 10 to print a solid image, and the image density was measured using a Macbeth reflection densitometer "RD918" (manufactured by Macbeth). The recording medium used was Yupo paper or plain paper (Multiace manufactured by Xerox Corporation).

(Evaluation Test 3: Inkjet Recording Characteristics:
(Uniformity of image) When printing solid images using YUPO paper as the recording medium, the occurrence of image unevenness and white streaks was evaluated. ○: No occurrence, △: Slightly observed, △: Clearly observed X.

(Evaluation Test 4: Inkjet Recording Characteristics:
(Bleeding and Margin) A thin line was drawn on a recording medium using plain paper, and bleeding due to feathering and a marginal state due to abnormal ink ejection were evaluated.も の indicates that fine lines are drawn with no bleeding and no discharge property abnormality, and △ indicates that there is slight disturbance, and × indicates that there is clear disturbance.
It was.

(Evaluation Test 5: Inkjet Recording Characteristics:
High-speed ejection) Using YUPO paper as the recording medium, printing mode of the printer is set to bidirectional printing, pass: 1, speed: 10, and a solid image of 1.5 reciprocations of the print head is printed with a width of 80 cm. When the print density near the middle is 100,
The print density near the start of printing and near the end of printing were relatively evaluated. The printing density was measured using a Macbeth reflection densitometer as in Evaluation Test 3.

The above evaluation results are summarized in Table 1.

[0075]

[Table 1]

From the results shown in Table 1, the aqueous ink composition for ink jet recording of the present invention has a high surface tension, and the actual printed matter also shows a sufficient image density. In addition, the uniformity of the image is sufficient, and bleeding due to feathering and deterioration of fine line reproducibility due to abnormal ink ejection are not observed, and it is clear that a high-resolution image can be obtained. In addition, since the density fluctuation of the image at the start position / intermediate position and the end position / intermediate position with respect to high-speed ejection is small, it is clear that the ink composition is capable of high-speed printing and capable of high definition and high speed. is there.

On the other hand, Comparative Example 1 shows a high surface tension and a sufficient image density, but white stripes are observed and the image uniformity is not sufficient. In addition, the print density tends to gradually decrease with respect to high-speed ejection, and the ability to follow high-speed ejection is insufficient. Although the surface tension also shows a high value in Comparative Example 2, the uniformity of the image, the level of bleeding and the level of the edge cut are poor, and a high-quality image cannot be obtained. In Comparative Example 3, the surface tension was low, and a slight occurrence of bleeding was observed. In addition, it is clear that the image density gradually decreases at the time of high-speed ejection, and the ink tracking ability is insufficient. When the ink tracking ability is insufficient, the heater is overheated in the thermal inkjet recording method, a phenomenon called kogation such as precipitation of material in the ink composition occurs, and an unrecoverable non-ejection state occurs, which is not preferable. . In Comparative Example 4, although high surface tension was exhibited, ink ejection was extremely unstable,
It is evident that the image uniformity is extremely poor, and the level of bleeding and edge cutting is poor and the fine line reproducibility is poor. Comparative Example 5
In this case, it is clear that the ink ejection properties are extremely unstable, the image uniformity is extremely poor, the level of bleeding and edge cutting is poor, and the fine line reproducibility is poor. In the high-speed ejection test, a non-ejection state occurred in the latter half of printing.

[0078]

According to the present invention, an aqueous ink composition for ink jet recording having a high surface tension can be obtained. When printed on plain paper, a high quality image with high fine line reproducibility is obtained with high uniformity of the image, no bleeding due to feathering and no abnormal ink ejection. In addition, high-speed ejection has sufficient ability, and an excellent ink capable of high-speed printing can be obtained.

 ────────────────────────────────────────────────── ─── Continued on front page F term (reference) 2C056 EA04 EA05 FC01 FC02 2H086 BA55 BA59 BA60 BA62 4J039 AD03 AD09 AD10 AD17 AE07 BA04 BC07 BC09 BC12 BE01 BE02 BE08 BE28 CA03 CA06 EA41 EA44 EA47 EA48 GA24

Claims (7)

[Claims] An aqueous ink composition for ink jet recording comprising at least water, a colorant, and an auxiliary solvent, wherein the auxiliary solvent has (1) a triol, (2) a glycol, and (3) a formula shown below. Condensation product of triol / alkylene oxide having a molecular weight of 300 or more (Wherein R ¹ is H or a C1-C4 alkyl group, R ²
Is a C1-C4 alkyl group, and a + b + c is 3-100. ), Wherein (1) is in the range of 1 to 20%, (2) is in the range of 1 to 30%, and (3) is in the range of 0.5 to 4% based on the total mass of the ink composition. A water-based ink composition for ink-jet recording, wherein the water-based ink composition has a viscosity of 35 mN / m or more. 2. The colorant is a pigment, and has a weight average molecular weight of 3 or more.
2. The aqueous ink composition for ink jet recording according to claim 1, wherein the ink composition contains 0.5 to 20% of an anionic polymer of 000 to 50,000 based on the total mass of the ink composition. 3. The aqueous ink composition for ink-jet recording according to claim 1, wherein the triol of the condensation product (3) of triol / alkylene oxide is trimethylolpropane. 4. The aqueous ink composition for ink-jet recording according to claim 3, wherein the alkylene oxide of the condensation product (3) of triol / alkylene oxide is ethylene oxide. 5. An anionic polymer having a weight average molecular weight of 50
It is a styrene acrylic copolymer of 00 to 20000,
And at least acrylic acid and methacrylic acid are contained as monomers constituting the polymer, and the weight ratio of acrylic acid to methacrylic acid is in the range of 1:10 to 10: 1. 5. The aqueous ink composition for inkjet recording according to any one of items 1 to 4. 6. The aqueous ink composition for ink-jet recording according to claim 2, wherein the anionic polymer is a graft polymer. 7. The aqueous ink composition for ink-jet recording according to claim 2, wherein the pigment is carbon black.