JP2000053899A - Water-based ink for inkjet recording - Google Patents

Abstract

(57) [Problem] To provide an ink jet recording ink in which ink ejection failure is prevented, and the accuracy of the landing position of ink droplets and the print density are improved. SOLUTION: At least one kind of compound A selected from the group consisting of urea, alkyl glycine and glycyl betaine, comprising a polymer emulsion obtained by impregnating polymer fine particles with a coloring material, and an alkyl or alkenyl sulfate and an alkyl or alkenyl sulfone An aqueous ink for inkjet recording, comprising at least one compound B selected from the group consisting of acid salts.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording ink in which defective ink ejection is prevented and the accuracy of the landing position of ink droplets and the print density are improved.

[0002]

2. Description of the Related Art Ink jet recording inks having improved water resistance include inks containing latex (JP-A-55-18412).
Containing a polymer or colored polymer latex (JP-A-5
JP-A-9-30873).

[0003] However, ink containing latex causes nozzle clogging. In addition, when printing is performed by a printer of a thermal jet system, the ejection is not stabilized, and the accuracy of the landing position of the ink droplet is reduced. Further, the print density does not become sufficiently high.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an ink jet recording ink in which ink ejection failure is prevented and the accuracy of the landing position of ink droplets and the print density are improved.

[0005]

According to the present invention, the above object has been attained by incorporating a specific compound in a water-based ink comprising an emulsion of a specific polymer.

[0006] That is, the present invention comprises a polymer emulsion obtained by impregnating polymer fine particles with a coloring material, comprising urea,
At least one compound A selected from the group consisting of alkyl glycine and glycyl betaine, and at least one compound B selected from the group consisting of alkyl or alkenyl sulfate and alkyl or alkenyl sulfonate
The above object has been achieved by providing a water-based ink for ink-jet recording characterized by containing:

[0007]

DETAILED DESCRIPTION OF THE INVENTION The aqueous ink for ink jet recording of the present invention (hereinafter simply referred to as "aqueous ink") comprises at least one compound A selected from the group consisting of urea, alkylglycine and glycylbetaine, Selected from the group consisting of sulfates and alkenyl sulfates (hereinafter collectively referred to as compound (I)) and alkyl sulfonates and alkenyl sulfonates (hereinafter collectively referred to as compound (II)) A combination with at least one compound B is used.

[0008] Among the compounds A, those having a general formula represented by R ₁ R ₂ NCH ₂ COOM are used as the alkylglycine.
The general formula, as R ₁ and R ₂ are the same or different hydrogen atom or an alkyl group having 1 to 5 carbon atoms are preferably used (where, R ₁ and R ₂ are not hydrogen atoms at the same time).
Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, and an isopropyl group. As M, a hydrogen atom, an alkali metal atom or an alkaline earth metal atom is used, and a hydrogen atom or an alkali metal atom is preferably used. Specific examples of the alkylglycine include N-methylglycine, N, N-dimethylglycine and N-methylglycine.
-Ethylglycine and the like.

As the compound A, one or more compounds can be used. Particularly preferably used are urea, N-methylglycine, N, N, N-trimethylglycine and glycylbetaine. Compound A is preferably contained in the aqueous ink of the present invention in an amount of 1 to 50% by weight, more preferably 2 to 35% by weight, and even more preferably 5 to 25% by weight. If the content of the compound A is less than 1% by weight, the emulsion is liable to be scorched on the head, so that the landing position accuracy of ink droplets may be reduced. Dischargeability is apt to decrease, so the printing quality on recording paper deteriorates,
The abrasion resistance may be reduced.

The above compound used as compound B
In (I) and (II), the alkyl group is preferably an alkyl group having 7 to 10 carbon atoms, specifically, an n-octyl group, an n-decyl group, an n-heptyl group, an n-nonyl group, and
-Methylhexyl, 2-ethylhexyl, 1-ethylpentyl, 1-methylheptyl, 3,5,5-trimethyl-1-hexyl and the like are used. On the other hand, the alkenyl group also preferably has 7 to 10 carbon atoms, specifically, 1-heptene group, 1-octene group,
A nonene group, a 1-decene group and the like are used. Examples of the salts in the compounds (I) and (II) include alkali metal salts such as Na and K, and quaternary ammonium salts such as NH ₄ ⁺ and N (CH ₂ CH ₂ OH) ₄ ⁺ . Preferred examples of the compound (I) include 2-ethylhexyl sulfate, n-octyl sulfate,
n-decyl sulfate and the like. On the other hand, preferred examples of the compound (II) include 2-ethylhexyl sulfonate, n-octane sulfonate, and n-decane sulfonate.

As compound B, either one of compounds (I) and (II) or a combination of both can be used. Compound B is preferably present in the aqueous ink of the present invention in an amount of from 0.01 to 0.01%.
The content is 5% by weight, more preferably 0.05 to 5% by weight, and even more preferably 0.1 to 2% by weight. If the content of the compound B is less than 0.01% by weight, the emulsion is liable to be scorched on the head, so that the landing position accuracy of the ink droplets may be reduced. If it exceeds 5% by weight, the ink penetrates the paper. The force is accelerated, and a sufficient print density may not be obtained.

The aqueous ink of the present invention is an aqueous dispersion in which the above-mentioned compound A and compound B are contained in a polymer emulsion. As the polymer emulsion, an emulsion of colored polymer fine particles colored with a coloring material is used, and particularly, an emulsion of polymer fine particles impregnated with a water-insoluble or poorly water-soluble coloring material is preferably used. In the present specification, "impregnated with a coloring material"
The expression means one or both of a state in which the coloring material is sealed in the polymer fine particles and a state in which the coloring material is adsorbed on the surface of the polymer fine particles. In this case, it is not necessary that all the coloring materials incorporated in the aqueous ink of the present invention be encapsulated or adsorbed in the polymer fine particles, and the coloring materials are dispersed in the emulsion as long as the effects of the present invention are not impaired. You may. In a preferred embodiment of the present invention, the water-based ink comprises an emulsion of polymer fine particles impregnated with a water-insoluble or poorly water-soluble colorant, and the compound A
And compound B.

The coloring material is not particularly limited as long as it is water-insoluble or hardly water-soluble and can be adsorbed by the polymer. In this specification,
The term “water-insoluble or poorly water-soluble” means that at least 10 parts by weight of a coloring material does not dissolve in 100 parts by weight of water at 20 ° C. It is not allowed. Examples of the coloring material include dyes such as oil-soluble dyes and disperse dyes, and pigments. In particular, oil-soluble dyes and disperse dyes are preferred from the viewpoint of good adsorption and encapsulation properties.

Each of the dyes used in the present invention is preferably an organic solvent,
For example, it is preferably dissolved in a ketone-based solvent at 2 g / L or more, more preferably 20 to 600 g / L.

The above-mentioned coloring material is contained in the water-based ink of the present invention in an amount of from 1 to 5.
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 print density may not be sufficient. If the amount is more than 30% by weight, the stability of the polymer fine particles with time is reduced, and the particle size increases. The dispersion stability of the emulsion itself tends to decrease. In addition, the amount of the coloring material is, in relation to the amount of the polymer,
It is preferably about 10 to 200% by weight, especially about 25 to 150% by weight, based on the weight of the polymer.

As the polymer forming the polymer emulsion, for example, a vinyl polymer, a polyester polymer, a polyurethane polymer and the like can be used. Particularly preferably used polymers are vinyl polymers and polyester polymers.

As the vinyl polymer, at least one polymer selected from the group consisting of a silicone macromer represented by the following formula (1) and acrylamide and methacrylamide monomers (excluding those having a salt-forming group): Monomer (a), polymerizable unsaturated monomer (b) having a salt-forming group, and a monomer copolymerizable with these monomers
It is preferable to use a vinyl-based polymer obtained by copolymerizing (c) with a radical polymerization initiator.

[0018]

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In the silicone macromer represented by the above formula (1), X represents a polymerizable unsaturated group, and specifically, groups such as CH ₂ ＣＨCH— and CH ₂ ＣC (CH ₃ ) — No. Y represents a divalent linking group, specifically -C
_{OO -, - COOC b H 2b} - ( wherein b is a number of 1 to 5) and phenylene group and the like, -COOC ₃ H
_6- is preferred. R ₅ represents a hydrogen atom; a lower alkyl group such as a methyl group or an ethyl group; an aryl group such as a phenyl group; an alkoxy group such as a methoxy group, and is preferably a methyl group. Z is a number average molecular weight of at least about 500 [gel permeation chromatography (hereinafter GPC)
To convert to polystyrene. same as below. And preferably a monovalent dimethyl siloxane polymer having a number average molecular weight of 800 to 5,000. n is 0 or 1, and preferably 1. m is an integer of 1 to 3, and is preferably 1.

As the silicone macromer, the following formula (1)
-1) to (1-4). Among them, those represented by the formula (1-1) are preferable, and particularly, the following formula (1)
-1-1) Those represented by [FM-0711 (trade name) manufactured by Chisso Corporation] are preferable.

[0021]

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[0022]

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Examples of the acrylamide or methacrylamide monomer include, for example, JP-A-9-2869.
No. 39, column 5, line 40 to column 7, line 22.

Examples of the polymerizable unsaturated monomer (b) having a salt-forming group include monomers described in JP-A-9-286939, column 7, line 23 to column 8, line 29.

Examples of the monomer (c) copolymerizable with the above monomers (a) and (b) include, for example, JP-A-9-28693.
The monomers described in column 8, line 30 to column 9, line 1 of JP-A-9 are mentioned. Among these, it is particularly preferable to use methyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, 2-ethylhexyl methacrylate, 2-methylstyrene, and 2-hydroxyethyl methacrylate.

Monomer (c) copolymerizable with the above monomer
Is not limited to the above, and a commercially available radical copolymerizable monomer can also be used. In particular, the following formula (2-1)
It is preferable to use one or more monomers represented by (2-4) from the viewpoint of storage stability of the emulsion.

[0027]

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Commercially available products of the above monomer (c) include styrene and / or acrylonitrile copolymer macromers having a methacryloyloxy group at one end [AN-6, AS-6 (trade name) manufactured by Toagosei Co., Ltd.] ], A methyl methacrylate polymer macromer having a methacryloyloxy group at one end [manufactured by Toagosei Co., Ltd., AA-6 (trade name)], a polyoxyethylene macromer having a methacryloyloxy group at one end [Shin Nakamura Chemical ( Co., Ltd., NK ester M-90Gne
w, M-40Gnew and M-20Gnew (trade name)], polyester macromers having a methacryloyloxy group at one end [FM4DX (trade name) manufactured by Daicel Chemical Industries, Ltd.] and the like.

When synthesizing the vinyl polymer, the monomer (a) is used in an amount of 1 to 40 with respect to the total amount of the monomers.
% By weight of the above monomer (b),
The copolymerization is preferably carried out using 25% by weight of the monomer (c) in a proportion of 35 to 96% by weight based on the total amount of the monomers.

The above vinyl polymer is disclosed in JP-A-9-28.
No. 6,939, column 9, lines 10 to 23, and is particularly preferably produced by a solution polymerization method.

In the copolymerization, a radical polymerization initiator is used, and examples thereof include those described in JP-A-9-286939, column 9, lines 24 to 36. Among these, it is particularly preferable to use an azo compound.
These radical polymerization initiators are used in an amount of 0.
It is preferable to use 001 to 2.0 mol%, particularly 0.01 to 1.0 mol%.

At the time of copolymerization, a polymerization chain transfer agent may be further added. A specific example thereof is disclosed in
No. 939, column 9, line 37 to column 10, line 10. Among them, mercaptoethanol, n-dodecylmercaptan, t-dodecylmercaptan, dimethylxanthogen disulfide, tetramethylthiuram disulfide, carbon tetrachloride, pentaphenylethane, acrolein, methacrolein, allyl alcohol, α-methylstyrene dimer (2, 4-Diphenyl-4-methyl-1-pentene is preferably 50% by weight or more), xanthene, and 2,5-dihydrofuran.

A specific copolymerization method is described in, for example,
No. 286939, column 10, lines 11-19. The weight average molecular weight of the vinyl polymer obtained by copolymerization (in terms of polystyrene by GPC; the same applies hereinafter) is preferably from 3,000 to 50,000.

As the polyester polymer, JIS
An acid value based on K0070 of 3 to 100 KOHmg /
g is preferably used. The acid value is 3 KOHm
g / g, a polymer emulsion in which a coloring material is stably impregnated may not be obtained.
If it exceeds g / g, the water resistance of the ink may be poor.
The acid value is more preferably 3 to 90 KOHmg / g,
More preferably, the content is 30 to 80 KOH mg / g, particularly preferably 50 to 70 KOH mg / g, which gives a good result in that the emulsion formability and stability are improved.

The polyester-based polymer has a number average molecular weight of preferably 500 to 100,000, more preferably 1,000 to 50,000, and still more preferably 1500.
~ 30000, even more preferably 2000-1500
A value of 0 is preferable from the viewpoints of scorching to the printer head, water resistance and scratch resistance of the printed ink, and emulsion formation.

Examples of the polyester-based polymer having the preferable physical properties described above include those containing a unit derived from a diol component represented by the following formula (3) in a polyester chain. In particular, a diol component represented by the following formula (3) (hereinafter, referred to as component (a)) and a polycarboxylic acid and / or a derivative thereof (hereinafter, referred to as component (b)) are obtained by co-condensation polymerization. Is preferred.

[0037]

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The diol component represented by the above formula (3) as the component (a) is preferably an alkylene oxide adduct of bisphenol A, particularly an ethylene oxide or propylene oxide adduct of bisphenol A.

The polyvalent carboxylic acid and / or the component (b)
Alternatively, as the derivative thereof, for example, at least one selected from the group consisting of polyvalent carboxylic acids, acid anhydrides thereof, and lower alkyl esters thereof is used.

As the polyvalent carboxylic acid, a divalent or higher carboxylic acid is used. As the lower alkyl ester of these polyvalent carboxylic acids, an alkyl ester having 1 to 4 carbon atoms is 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 is obtained by co-condensation polymerization of the diol component and a polycarboxylic acid and / or a derivative thereof, and the co-condensation polymerization method is not particularly limited, and a known method can be used. The molar ratio of the component (a) to the component (b) is such that the component (b) is present in an amount of 0.01 to 1.4 moles, particularly 0.1 to 1.2 moles, per mole of the component (a). Molar is preferred.

Of the above polyesters, other than the diol component represented by the above formula (3) (the above component (a)), trimellitic anhydride (hereinafter, also referred to as the component (b) ′) and trimellitic anhydride (Hereinafter referred to as "polyester A") obtained by copolycondensation of a polycarboxylic acid and / or a derivative thereof (hereinafter also referred to as "(b)").

By using the component (b) ′, the formability and stability of the emulsion and the amount of colorant adsorbed are improved.
The bonding form of trimellitic anhydride in the polyester A is such that the cyclic anhydride site in trimellitic anhydride is opened,
It is in a state of being incorporated in the polyester chain. It is preferable to use the acid anhydride instead of the trimellitic acid itself, particularly since the effects of high reactivity during the synthesis of the polyester and high formation of the emulsion are exhibited.

The above (b) "used for the above polyester A
It is preferable to use a component obtained by removing trimellitic anhydride from the above-mentioned component (b) used in the above-mentioned polyester.

The molar ratio of the component (a), the component (b) ′, and the component (b) ″, which is a copolycondensation component in the polyester A, is as follows: b) The component is 0.
It is preferably from 0.5 to 0.7 mol, particularly preferably from 0.1 to 0.5 mol. The component (b) "is present in an amount of 0.3 to 1.2 mol, especially 0.5 to 1.2 mol.
1.1 mole is preferred.

Polyesters obtained by copolycondensation with the addition of dimer acid to the polyester A component are also preferred. The dimer acid is a substance synthesized by a polymerization reaction of two unsaturated fatty acids, and includes, for example, an acyclic dimer acid, a monocyclic dimer acid, and a bicyclic dimer acid. Used. Commercially available products include Unidim 22 (trade name, manufactured by Union Cap Co., Ltd.) and Haridima (trade name, manufactured by Harima Kasei Co., Ltd.). By using the dimer acid, the formability of the emulsion,
The stability is improved, and the coloring material is easily impregnated. Acyclic dimer acids are particularly preferred from the viewpoint of further improving the formability and stability of the emulsion.

The dimer acid is used in an amount of 0.001 to 0.7 mol, especially 0.01 to 0.5 mol per 1 mol of the component (a).
Molar is preferred. Other preferred component ratios are as described above.

JIS K 0070 of the above polyester
Is preferably 3 to 100 KOHmg / g. If the amount is less than 3 KOH mg / g, the stability of the emulsion impregnated with the coloring material may decrease,
If it exceeds OH mg / g, the water resistance of the ink may be poor. The acid value is more preferably 3 to 70 KOHmg /
g, more preferably 10 to 60 KOH mg / g, particularly preferably 25 to 50 KOH mg / g. The acid value is controlled, for example, by changing the addition ratio between the diol component and the polycarboxylic acid and / or a derivative thereof, using a carboxylic acid ester, or blocking the acid with a monohydric alcohol to control the reaction. Etc. can be adjusted.

The polyester preferably has a glass transition point (hereinafter, referred to as Tg) of 20 ° C. or higher.
50-150 ° C is preferred. The temperature is preferably 20 ° C. or higher for an ink jet system using a piezoelectric element, and 30 ° C. or higher for an ink jet recording system using thermal energy.
Outside of these preferred ranges, the polyester tends to solidify at the nozzle of the printer, and the nozzle may be clogged. In addition, when the printed papers are overlapped, paper reflection of the ink may occur. In addition, Tg is a differential scanning calorimeter (hereinafter, referred to as a
DSC).

The above-mentioned various polymers are used in the water-based ink of the present invention in order to ensure a sufficient print density and to prevent clogging of the printer head due to thickening of the ink due to ink evaporation and aggregation of polymer fine particles. It is preferable that 1 to 30% by weight, particularly 2 to 20% by weight as a solid content is incorporated therein.

The content of the above polymer in the water-based ink of the present invention is such that the weight ratio of the polymer to the compound A (former / latter) is 1/5 to 5 in relation to the content of the compound A and the compound B. It is preferably 5/1, particularly 1/3 to 3/1, and the weight ratio of the polymer to the compound B (the former / the latter) was 2/1 to 500/1, particularly 4/1 to 100.
/ 1 is preferred.

The aqueous ink of the present invention is an aqueous emulsion using water (preferably ion-exchanged water) as a medium. The amount of water is preferably 50 to 98% by weight, more preferably 55 to 95% by weight, and still more preferably 60 to 90% by weight.
It is.

The water-based ink of the present invention may further contain a wetting agent such as a polyhydric alcohol within a range not exceeding the preferable viscosity for ink jet recording ink. The preferred compounding amount is 0.1 to 50% by weight, particularly 1 to 30% by weight in the aqueous ink of the present invention.

In addition to the above-mentioned components, the water-based ink of the present invention contains a dispersant such as various cationic, anionic or nonionic surfactants, a defoaming agent such as silicone, and the above-mentioned various surfactants. Conventionally known various types such as surface tension adjusters, ultraviolet absorbers such as benzotriazole, benzophenone, salicylate and cyanoacrylate, fungicides such as chloromethylphenol, chelating agents such as EDTA, and oxygen absorbers such as sulfites. Additives may be blended.

From the viewpoint of reducing the particle size of the polymer fine particles and the stability of the emulsion, it is desirable that the above dispersant is usually incorporated in the aqueous ink of the present invention in an amount of 0.01 to 10% by weight, preferably 0.05 to 10% by weight. -5% by weight, more preferably 0.1-1% by weight.

The antifoaming agent is contained in the aqueous ink of the present invention in an amount of 0%.
To 2% by weight, in particular 0.001 to 2% by weight, in particular 0.
It is preferable that 005 to 0.5% by weight be blended. When the amount of the defoaming agent exceeds 2% by weight, the generation of bubbles is suppressed, but at the time of printing, repelling occurs in the ink and the printing quality may deteriorate.

As the surface tension adjusting agent, the above-mentioned silicone-based antifoaming agents and various cationic, anionic or nonionic surfactants can be used. In particular, the use of a silicone-based antifoaming agent, an ethylene oxide compound of an alkyl phenol, or an ethylene oxide adduct of acetylene glycol suppresses the generation of bubbles, facilitates adjustment of the surface tension of the ink, and causes ink ejection and bleeding. This is preferable in that there is little unevenness in print density.

In using the surface tension modifier, one or more of these compounds can be used. The mixing amount of these surface tension adjusters is 0.005 to 1 in the aqueous ink of the present invention from the viewpoint of print quality and ink stability.
Desirably, it is 5% by weight.

The aqueous ink of the present invention has a temperature of 20 ° C.
The surface tension at the point of 2
It is preferably from 5 to 65 mN / m, more preferably from 25 to 55 mN / m, and still more preferably from 28 to 50 mN / m.
/ M. If the surface tension is less than 25 mN / m, bleeding of ink and deterioration of printing quality may occur, and ink leakage may occur from a print head nozzle of an inkjet printer. The surface tension is measured using an automatic surface tensiometer (CBVP-Z type) manufactured by Kyowa Interface Science Co., Ltd.
Can be measured.

The water-based ink of the present invention has a viscosity at 20 ° C. of 0.5 to 8 mPa · s from the viewpoint of ejection stability.
sec, more preferably 0.5 to
5 mPa · sec, more preferably 1 to 5 mPa · sec
c, and still more preferably 1 to 3 mPa · sec.
If the viscosity is less than 0.5 mPa · sec, bleeding of the ink becomes remarkable, and ink may leak from the print head nozzles of the ink jet printer. On the other hand, when the viscosity exceeds 8 mPa · sec, the viscosity of the ink for inkjet becomes too high, and the ink is not supplied to the print head. . The above viscosity was measured using an E-type viscometer (VISCONIC ELD) manufactured by Tokyo Keiki Co., Ltd., or a rotational vibration type viscometer (Viscomate VM-V) manufactured by Nikkato Tokyo Branch.
100).

In the production of the water-based ink of the present invention, first, the above-mentioned polymer emulsion is prepared. That is, the polymer and the coloring material are added to an organic solvent, and then,
A neutralizing agent and, if necessary, a surfactant are added to the resulting solution or dispersion to ionize the salt-forming groups in the polymer. Then, when adding water to the resulting mixture,
Emulsification is performed using a known emulsification method, for example, a phase inversion emulsification method or a forced emulsification method. From the viewpoint of emulsion stability, a phase inversion emulsification method is preferable for a polyester emulsion, and a forced emulsification method is preferable for a vinyl emulsion. Thereafter, the organic solvent is distilled off from the emulsion by heating the system under reduced pressure. As a result, an aqueous emulsion of polymer fine particles impregnated with the coloring material is obtained.

By dissolving various hydrophobic stabilizers together with the coloring material in the water-insoluble organic solvent at the time of preparing the emulsion, the stabilizer can be encapsulated in the polymer. Examples of the stabilizer include ultraviolet absorbers such as benzotriazole, benzophenone, salicylate and cyanoacrylate described above; primary antioxidants such as hindered phenols and amines;
Preferred are secondary antioxidants such as sulfur type and ultraviolet stabilizers such as hindered amine type.

After obtaining an aqueous emulsion of polymer fine particles impregnated with a coloring material as described above, the above-mentioned compound A and compound B and, if necessary, other components are added to the emulsion. The water-based ink of the present invention is obtained.

In preparing the aqueous ink of the present invention, it is preferable to remove coarse particles in the ink. For example,
The prepared ink is filtered under pressure with a filter or treated with a centrifuge to remove particles having a size of preferably 2,000 nm or more, more preferably 1,000 nm or more, and more preferably 500 nm or more. Is obtained.

The pH of the polymer emulsion thus obtained and the final aqueous ink are adjusted to pH = 5 to 12, preferably 5, to ensure the stability of the emulsion.
It is preferable to adjust so as to be 5 to 10. For example, by adding sodium hydroxide to the emulsification step of the polymer emulsion or the final aqueous ink to neutralize it,
adjust.

The ink-jet recording ink of the present invention comprises:
It is mainly used for ink-jet recording, but can also be used as ink for writing implements such as general fountain pens, ball-point pens, and felt-tip pens.

[0067]

Embodiments will be described below. In addition, "%" in the example
And "parts" are by weight unless otherwise specified.

[Production Example 1] In a reactor, 20 parts of methyl ethyl ketone as a polymerization solvent and 20 parts of a polymerizable unsaturated monomer were added.
The monomers and the polymerization chain transfer agent described in the column of initially charged monomers in Table 1 were charged, and nitrogen gas replacement was sufficiently performed. Under a nitrogen atmosphere, the temperature of the mixture in the reaction vessel was raised to 65 ° C. while stirring. Separately, the monomers and polymerization chain transfer agents described in the column of dropped monomers in Table 1, 60 parts of methyl ethyl ketone, and 0.2 parts of 2,2′-azobis (2,4-dimethylvaleronitrile) were used. The mixed solution obtained by mixing and sufficiently replacing with nitrogen was gradually dropped into the reaction vessel over 3 hours. Two hours after the end of the dripping,
A solution of 0.1 part of 2,2′-azobis (2,4-dimethylvaleronitrile) dissolved in 5 parts of methyl ethyl ketone is added, and the mixture is further aged at 65 ° C. for 2 hours and at 70 ° C. for 2 hours to obtain a vinyl polymer solution. I got

A part of the obtained vinyl polymer solution was
It was dried at 105 ° C. under reduced pressure for 2 hours and isolated by completely removing the solvent. The weight-average molecular weight of this vinyl polymer by GPC using tetrahydrofuran as a solvent is about 10,000 and the Tg by DSC
Was 180 ° C.

The vinyl polymer solution obtained above was dried under reduced pressure, and 5 g of the vinyl polymer obtained was mixed with 25 g of toluene and Vail Fast Bl.
5ue of 2ue [manufactured by Orient Chemical Co., Ltd.] was added and completely dissolved, and 2 g of an aqueous sodium hydroxide solution was added to partially neutralize the salt-forming groups of the vinyl polymer. Next, 300 g of ion-exchanged water was added and stirred, and then emulsified for 30 minutes using a microfluidizer (trade name, manufactured by Microfluidizer), which is an emulsifying apparatus. The obtained emulsion was completely removed by removing toluene at 60 ° C. under reduced pressure, and further concentrated by removing a part of water to obtain an emulsion of vinyl polymer fine particles impregnated with a hydrophobic dye (average particle size: 98 nm). , Solid content: 10%).

[0071]

[Table 1]

Example 1 The emulsion of the vinyl-based polymer fine particles obtained in Production Example 1 was mixed with each component according to the following formulation, and the resulting dispersion was filtered through a 0.2 μm filter to obtain dust and coarse particles. Was removed to obtain an aqueous ink. Using this ink, printing was performed with a commercially available Canon Color Bubble Jet Printer (Model No. BJC-420J), and the dirt on the face of the print head, the accuracy of the landing position of the ink droplet, and the print density were evaluated by the following methods. did.
Table 2 shows the results.

-60 g of the emulsion obtained in Production Example 1-5 g of urea (Compound A)-0.5 g of sodium n-octyl sulfate (Compound B)-5 g of ethylene glycol-5 g of glycerin-24.5 g of ion-exchanged water

<Evaluation of the Stain on the Face Surface of the Print Head and the Accuracy of the Impact Position of the Ink Droplets> The solid print was performed on the high-quality paper for ink jet printing (HR101 manufactured by Canon Inc.).
The accuracy of the ink landing position when 3,000 prints were made on zero sheets and character printing, and stains on the face surface of the print head after printing were observed, were evaluated according to the following criteria. <Ink landing position> A: Both solid and character printing are normal. ；: The landing position in character printing is normal, and in solid printing, streaks are seen due to the deviation of the landing position. Δ: Disturbance is observed in the landing position in both solid and character printing. X: Printing blur occurs during printing. Character cannot be identified. <Stain on the face> A: There is no stain on the face for both solid and character printing. ；: There is no dirt on the face surface in character printing, but dirt is seen on the face surface in solid printing. However, the nozzle is not closed. Δ: Stain is seen on the face surface in both solid and character printing. However, the nozzle is not closed. ×: Nozzle clogged during printing. <Print density> Solid printing is performed on recycled paper for PPC [manufactured by Nippon Kaishi Paper Co., Ltd.], and after natural drying in a room for 24 hours, the optical density is measured with a Macbeth densitometer RD918 (manufactured by Macbeth). did. The print density was 1.4.
If it is 0 or more, there is no quality problem.

Examples 2 to 6 Water-based inks were produced in the same manner as in Example 1 except that the compounds shown in Table 2 were used instead of the compounds A and B used in Example 1. The obtained water-based ink was evaluated in the same manner as in Example 1. Table 2 shows the results.

Comparative Example 1 An aqueous ink was produced in the same manner as in Example 1 except that urea was not used. The obtained water-based ink was evaluated in the same manner as in Example 1. Table 2 shows the results.

[0077]

[Table 2]

[Production Example 2] Polyoxypropylene (2.
2) 90 g of a dimer acid mixture containing 1050 g of 2,2-bis (4-hydroxyphenyl) propane, 30% of an acyclic dimer acid compound and 10% of a monocyclic dimer acid compound, 270 g of fumaric acid, and trimellitic anhydride 12
0 g and 1.5 g of hydroquinone were placed in a reactor and reacted while stirring at 210 ° C. under a nitrogen stream. 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 100 ° C. The obtained polyester was a pale yellow solid, and the Tg by DSC was 58 ° C. Further, the acid value of the polyester based on JIS K 0070 was 53 KOH mg / g, and the number average molecular weight (in terms of polystyrene by gel permeation chromatography) was 5,500. Next, 150 g of the above polyester, 70 g of an oil-soluble dye (manufactured by Orient Chemical Co., Ltd., OIL BLACK 860) and 500 g of tetrahydrofuran were put into a reactor, and after purging with nitrogen, the mixture was stirred to completely dissolve the polyester and the oil-soluble dye in tetrahydrofuran. Then, dimethylethanolamine 1
3.90 g and 1.13 g of sodium hydroxide were added to ionize the carboxyl groups in the polyester. Further, a mixed aqueous solution of 960 g of ion-exchanged water and 3 g of a formalin condensate of naphthalenesulfonic acid (HLB value 8.51) was dropped and stirred, and then heated to 40 ° C. under reduced pressure to remove tetrahydrofuran and some water. After removal, an emulsion of polyester fine particles impregnated with a coloring material (oil-soluble dye) (average particle size: 20 nm, solid content concentration: 20%) was obtained.

Example 7 Using the emulsion obtained in Production Example 2, the respective components were mixed according to the following formulation, and the obtained dispersion was filtered with a 0.2 μm filter to remove dust and coarse particles. Thus, a water-based ink was obtained. The same evaluation as in Example 1 was performed on the obtained ink. Table 3 shows the results.
Shown in

-60 g of the emulsion obtained in Production Example 2-5 g of urea (compound A)-0.5 g of sodium n-octyl sulfate (compound B)-5 g of ethylene glycol-5 g of glycerin-24.5 g of ion-exchanged water

Examples 8 to 12 Water-based inks were produced in the same manner as in Example 7, except that the compounds shown in Table 3 were used instead of the compounds A and B used in Example 7. The obtained water-based ink was evaluated in the same manner as in Example 1. Table 3 shows the results.

Comparative Example 2 An aqueous ink was produced in the same manner as in Example 7 except that urea was not used. The obtained water-based ink was evaluated in the same manner as in Example 1. Table 2 shows the results.

[0083]

[Table 3]

As is clear from the results shown in Tables 2 and 3, the water-based ink of the embodiment, which is composed of an emulsion of polymer fine particles impregnated with a coloring material and contains a specific compound, causes stains on the face surface of the print head. It can be seen that the accuracy of the landing position of the ink droplet is high and the printing density is sufficient. Further, although not shown in the table, the aqueous inks of the examples had high liquid stability, and were excellent in water resistance and scratch resistance.

[0085]

According to the water-based ink of the present invention, it is possible to prevent ink ejection failure due to contamination of the face surface of the print head, improve the accuracy of the landing position of ink droplets, and improve the print density on plain paper. Is improved. Further, the aqueous ink of the present invention has high liquid stability, and is excellent in water resistance and scratch resistance.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2C056 FC01 2H086 BA51 BA53 BA59 BA62 4J039 AD01 AD03 AD08 AD10 AD12 AE04 AE05 AE11 BC19 BC33 BC34 BC37 BC54 BE33 CA06 EA12 EA21 EA36 EA38 EA41 EA44 EA46 GA24

Claims (5)

[Claims] 1. A compound emulsion comprising a polymer fine particle impregnated with a coloring material, at least one compound A selected from the group consisting of urea, alkyl glycine and glycyl betaine, and an alkyl or alkenyl sulfate and an alkyl or alkenyl. A water-based ink for inkjet recording comprising at least one compound B selected from the group consisting of sulfonic acid salts. 2. The aqueous ink for ink-jet recording according to claim 1, wherein the compound A is contained in an amount of 1 to 50% by weight, and the compound B is contained in an amount of 0.01 to 5% by weight. 3. The polymer emulsion according to claim 1, wherein said polymer emulsion is obtained by impregnating a polymer fine particle with a water-insoluble or poorly water-soluble coloring material, and the polymer forming said polymer emulsion is a vinyl-based polymer or a polyester-based polymer. Item 3. An aqueous ink for inkjet recording according to item 1 or 2. 4. The aqueous ink for ink-jet recording according to claim 1, wherein the polymer is contained in an amount of 1 to 30% by weight as a solid content. 5. The weight ratio between the polymer and the compound A (former / latter) is 1/5 to 5/1, and the weight ratio between the polymer and the compound B (former / latter) is 2/1. ~ 5
The aqueous ink for inkjet recording according to any one of claims 1 to 4, wherein the ratio is 00/1.