JPH09217030A - Aqueous ink - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an aqueous ink for an inkjet recording having improved water resistance, fixing ability and image quality of a printed mater by enclosing a dye in polyester micelles having a specific average particle diameter. SOLUTION: This aqueous ink is obtained by including a dye in polyester suspensions having an average particle diameter of 0. 005-0.5μm. The polyester preferably has an acid value determined according to JIS K 0070 of 3-70KOHmg/ g, and the polyester is preferably produced by condensing-copolymerizing a diol component of the formula [R is an alkylene; (x) and (y) are each an integer of one or more, and the average of (x)+(y) is 2-7] with an acid component of one kind or more selected from among a polyvalent carboxylic acid having a divalent or a higher valent, its anhydride and lower alkyl esters of the acid. The polyester suspension can be obtained by dissolving the polyester together with the dye in a solvent, ionizing the carboxylic acid in the polyester by adding a neutralizing agent and subsequently removing the solvent by distillation after adding water to change the phase to an aqueous phase.

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 having improved fixability and image quality, and particularly to a water-based ink useful as an ink for inkjet recording.

[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. By using the water-soluble dye, the ink is less likely to be clogged in the nozzle, but on the other hand, there is a problem that the water resistance and the fixing property are poor. Therefore, the composition of the ink is important for improving the water resistance and fixing property of the ink.

In order to improve the water resistance of the ink for ink jet recording, a pigment is used as the ink (JP-A-4-28776, JP-A-4-189876, JP-A-4-359071 and JP-A-4-359072). Or a dye excellent in water resistance is used (US Pat. No. 49.
No. 63189) has been proposed.

However, when a pigment is used as the ink, there is a possibility that the color saturation of the printed matter, that is, the image quality may be deteriorated and that the nozzle may be clogged. It cannot be said that the other proposals have sufficiently solved the problems of improving water resistance, fixing property and image quality.

Therefore, an object of the present invention is to provide a water-based ink having improved water resistance, fixability and image quality of printed matter.

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 inventors of the present invention have made extensive studies in order to achieve the above object. As a result, encapsulating a dye in a micelle of polyester having a specific average particle diameter impairs the coloring property of the dye. It was found that the water resistance, the fixability and the image quality of the printed matter are improved without being damaged.

The present invention has been made on the basis of the above findings, and comprises a polyester suspension in which a dye is encapsulated, and the polyester suspension has an average particle diameter of 0.005 to 0.5 μm. The above object is achieved by providing the following.

The present invention also provides a water-based ink for ink-jet recording, characterized by using the above-mentioned water-based ink.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The water-based ink of the present invention comprises a polyester suspension in which a dye is encapsulated, and the polyester suspension has an average particle size of 0.005 to 0.
It is characterized by being 5 μm. That is, the dye is encapsulated in a micelle having a specific average particle size formed by at least polyester. In the water-based ink of the present invention, dye-encapsulated polyester micelles are present as suspensions in water with a specific average particle size.

As the above-mentioned polyester, those capable of forming micelles capable of encapsulating all of the dyes therein are preferable, but even those capable of forming micelles capable of encapsulating even a part of the dye therein, It can be used without particular limitation as long as the effects of the invention are not impaired.

The average particle size of the suspension made of polyester is 0.005 to 0.5 μm. If the average particle diameter is less than 0.005 μm, bleeding of printed matter may occur and the dispersion stability of the suspension itself may be deteriorated. On the other hand, even if the average particle diameter exceeds 0.5 μm, the dispersion stability of the suspension itself may be reduced. Further, by setting the average particle diameter within the above range, the fixing property of the printed matter and the image quality can be improved particularly effectively. The average particle diameter is preferably 0.01 to 0.2 μm, particularly from the viewpoint of improving the ink discharge amount and print density and preventing clogging when the ink of the present invention is used as an inkjet ink. .02
It is more preferable that the thickness is 0.1 μm.

The polyester preferably used in the present invention is a polyester having an acid value of 3 to 70 KOHmg / g according to JIS K0070,
Particularly preferably used are one or more acid components selected from the group consisting of a diol component represented by the following formula (1), a divalent or higher polyvalent carboxylic acid, an acid anhydride thereof and a lower alkyl ester thereof. Is a polyester having an acid value of 3 to 70 KOHmg / g.

[0015]

Embedded image (In the formula, R represents an alkylene group, for example, an ethylene or propylene group, x and y represent the same or different integers of 1 or more, and the average value of x + y is 2 to 7.)

The above polyester will be described in detail below. As described above, the polyester is JIS K 0
The acid value based on 070 is preferably 3 to 70 KOHmg / g. If the acid value is less than 3 KOHmg / g, a suspension in which the dye is stably encapsulated may not be obtained, and if it exceeds 70 KOHmg / g, the water resistance of the ink may be inferior. It is preferable.

Explaining the diol component represented by the above formula (1), the diol component is bisphenol A.
Alkylene oxide adduct of bisphenol A, preferably ethylene oxide or propylene oxide adduct of bisphenol A, and 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 above-mentioned acid component will be explained. As the acid component, as mentioned above, a polyvalent carboxylic acid having a valence of 2 or more,
At least one selected from the group consisting of the acid anhydride and the lower alkyl ester thereof is used.

As the above-mentioned divalent or higher polyvalent carboxylic acid,
Divalent carboxylic acids and trivalent or higher carboxylic acids are used. Examples of the divalent carboxylic acid include maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, succinic acid, adipic acid, sebacic 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, isooctyl succinic acid and the like are preferably used. On the other hand, examples of trivalent or higher carboxylic acids include 1,2,4-benzenetricarboxylic acid, 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,
1,2,7,8-octanetetracarboxylic acid, pyromellitic acid, trimellitic anhydride, embol trimer acid and the like are preferably used. In addition, as the lower alkyl esters of these divalent or higher polycarboxylic acids, alkyl esters having 1 to 4 carbon atoms are preferably used. Above all, as the polyvalent carboxylic acid, a divalent carboxylic acid such as maleic acid, fumaric acid, itaconic acid, phthalic acid, isophthalic acid, terephthalic acid or succinic acid, or 1,2,4-benzenetricarboxylic acid is used. It is preferable.

The polyester is preferably obtained by copolycondensation of the diol component and the acid component. The method of the copolycondensation is not particularly limited, and a known method is used.

The acid value of the polyester is adjusted by, for example, changing the addition ratio of the diol component and the acid component, using a carboxylic acid ester, or blocking the acid with a monohydric alcohol. You can

The above polyester has a number average molecular weight (converted to polystyrene by gel permeation chromatography) of 500 to 100,000, particularly 1,000.
It is preferably from 10,000 to 10,000 from the viewpoints of scorching on the printer head, water resistance of the ink after printing, and formability of the suspension.

It is also preferable that the polyester has a Tg (glass transition point) measured by DSC (differential scanning calorimetry) of 25 ° C. or higher, more preferably 40 ° C. or higher, and particularly 40 ° C. or higher and 150 ° C. or lower. . If the Tg is less than 25 ° C., when the water-based ink of the present invention is used in, for example, an inkjet printer, the polyester may solidify in the nozzle of the printer and the nozzle may be clogged. In addition, when paper printed using the water-based ink of the present invention is overlaid, paper reflection of the ink may occur. The Tg of the polyester can be adjusted, for example, by changing the addition ratio of the diol component and the acid component.

Next, the dye encapsulated by the polyester micelles will be explained.
Any dye can be used without particular limitation as long as it can be encapsulated by the polyester, and examples thereof include oil dyes, disperse dyes, direct dyes, acid dyes and basic dyes, but from the viewpoint of good encapsulation property. It is particularly preferable to use an oil dye and a disperse dye. The disperse dye is not limited to the following, but a particularly preferred specific example is C.I. I. Disperse Yellow 5, 4
2,54,64,79,82,83,93,99,10
0, 119, 122, 124, 126, 160, 18
4: 1, 186, 198, 199, 204, 224 and 237; I. Disperse Orange 13, 29, 3
1: 1, 33, 49, 54, 55, 66, 73, 11
8, 119 and 163; I. Disperse Red 5
4, 60, 72, 73, 86, 88, 91, 92, 9
3, 111, 126, 127, 134, 135, 14
3, 145, 152, 153, 154, 159, 16
4,167: 1,177,181,204,206,2
07, 221, 239, 240, 258, 277, 27
8, 283, 311, 323, 343, 348, 356
And 362; I. Disperse Violet 33;
C. I. Disperse Blue 56, 60, 73, 87,
113, 128, 143, 148, 154, 158, 1
65, 165: 1, 165: 2, 176, 183, 18
5, 197, 198, 201, 214, 224, 22
5, 257, 266, 267, 287, 354, 35
8, 365 and 368; and C.I. I. Disperse Green 6: 1 and 9; The oily 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, 29, 56 and 82; C.I.
I. Solvent Red 1, 3, 8, 18, 24, 2
7, 43, 51, 72, 73, 132 and 218;
I. Solvent Violet 3; C.I. I. Solvent Blue 2, 11, and 70; 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, but particularly preferable specific examples thereof include 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; C.I. I. Acid Yellow 23; C.I. I. Acid Red 51, 87
And 92; and C.I. I. Acid Blue 1, 9 and 74 and the like. The basic dye is not limited to the following, but particularly preferable specific examples thereof include C.I. I. Basic Yellow 2 and 1
1; I. Basic Red 1 and 13; C.I. 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 dissolved in a solvent, for example, a ketone solvent in an amount of 20 g / l or more, from the viewpoint of being efficiently encapsulated in the polyester by the phase inversion emulsification which will be described later, and preferably 100 to 600 g. It is more preferred that the solution dissolves in 1 / l.

In the water-based ink of the present invention, the above polyester is preferably blended in the ink in an amount of 0.5 to 50% by weight, more preferably 2 to 30% by weight. 0.5% by weight of the above polyester
If the amount is less than 50% by weight, the print density is insufficient, and if it exceeds 50% by weight, the storage stability of the suspension as ink decreases, and especially when used in an inkjet printer, the ink accompanying evaporation of ink at the nozzle tip portion Since there is a case where the printer head is clogged due to the increase in viscosity and the aggregation of the suspension, it is preferable to set it within the above range.

On the other hand, the above dye is contained in the ink in an amount of 1 to 30.
It is preferable that the composition is blended in a weight percentage of 1.5 to 25 wt%.
More preferably, it is blended. Compounding amount of the above dye is 1
If it is less than 30% by weight, the print density is insufficient, and if it exceeds 30% by weight, the stability of the particle size of the suspension with time deteriorates and the average particle size tends to increase. .

The water-based ink for ink jet recording of the present invention contains, in addition to a polyester suspension in which water is used as a medium and in which the above dye is encapsulated, various conventionally known additives such as wetting agents such as polyhydric alcohols. , Dispersants, antifoaming agents such as silicones, antifungal agents such as chloromethylphenol and / or chelating agents such as EDTA, and
An oxygen absorbent such as sulfite may be contained.

Here, examples of the wetting agent include ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, glycerin, diethylene glycol diethyl ether, diethylene glycol monobutyl ether, ethylene glycol monomethyl ether, ethylene glycol mono. Ethyl ether,
Ethylene glycol monobutyl ether, methyl carbitol, ethyl carbitol, butyl carbitol, ethyl carbitol acetate, diethyl carbitol,
Polyethylene alcohols such as triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, propylene glycol monomethyl ether and thiodiglycol, and their ethers, acetates, N-methyl-2-pyrrolidone, 1,3-dimethylimidazolidi One or more of nitrogen-containing compounds such as non-, triethanolamine, formamide, dimethylformamide, and dimethyl sulfoxide can be used. The amount of these wetting agents is not particularly limited, but preferably 0.1 to 50% by weight, more preferably 0.1 to 30% by weight, in the water-based ink of the present invention. it can.

The dispersant is not particularly limited, but examples of the anionic surfactant include higher fatty acid salts, higher alkyl dicarboxylic acid salts, higher alcohol sulfate ester salts, higher alkyl sulfonates, As a cationic surfactant such as condensate of higher fatty acid and amino acid, sulfosuccinate ester salt, naphthenate, etc.
Aliphatic amine salts, quaternary ammonium salts, sulfonium salts, phosphonium salts and the like, amphoteric surfactants such as betaine type compounds, nonionic surfactants such as fatty acid ester type of polyoxyethylene compounds, polyethylene oxide condensation type and the like. For example, one kind or two or more kinds of these can be used upon use. Also, as a polymer dispersant, proteins such as gelatin and casein,
Natural rubber such as gum arabic, glucooxide such as saponin, methyl cellulose, carboxymethyl cellulose,
Cellulose derivatives such as hydroxymethyl cellulose, natural polymers such as lignin sulfonate, shellac, polyacrylate, styrene-acrylic acid copolymer salt, vinylnaphthalene-acrylic acid copolymer salt, styrene-maleic acid copolymer Salt, vinylnaphthalene-maleic acid copolymer salt, β-naphthalenesulfonic acid formalin condensate salt,
Examples thereof include anionic polymers such as polyphosphoric acid, nonionic polymers such as polyvinyl alcohol, polyvinylpyrrolidone, and polyethylene glycol, and at the time of use, one or more of these can be used. Above all,
It is particularly preferable to use the compound represented by the following formula (2) from the viewpoint that the average particle size of the suspension can be reduced.

[0031]

Embedded image (In the formula, R ′ represents a hydrogen atom, a hydrocarbon group having 1 to 10 carbon atoms or a hydroxyl group, R ″ represents a hydrocarbon group having 1 to 5 carbon atoms, M represents a monovalent cation, and l represents Indicates an integer of 1 to 1000.)

In the above formula (2), R'is a hydrogen atom,
It represents a hydrocarbon group or a hydroxyl group having 1 to 10 carbon atoms, and preferably a hydrogen atom is used. Also, R "is a carbon number of 1 to
5 is shown, and a methylene group is preferably used. Further, M represents a monovalent cation, and preferably an alkali metal ion such as sodium or potassium is used. In addition, l represents an integer of 1 to 1000,
It is preferably 100 to 800. In addition, the above equation (2)
The HLB value of the compound represented by is preferably 5 to 15 from the viewpoint of exhibiting the effect as a dispersant and suppressing the increase in the average particle diameter of the suspension.

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

The compounding amount of the compound represented by the above formula (2) is not particularly limited, but 0.01% in the water-based ink of the present invention.
Preferably, it is blended at 10 to 10% by weight. If the compounding amount of the compound is less than 0.01% by weight, it is difficult to reduce the particle size of the suspension. If it exceeds 10% by weight, the average particle size of the suspension increases, the suspension stability decreases, and gelation occurs. Therefore, it is preferable to be within the above range. More preferably, the compounding amount of the compound represented by the above formula (2) is in the aqueous ink of the present invention.
It is 0.1 to 1% by weight.

The defoaming agent is not particularly limited, but it is preferable to use a compound represented by the following formula (3), especially a compound represented by the following formula (4) at the time of ink preparation. It is particularly preferable from the viewpoint of suppressing the generation of bubbles and controlling the surface tension of the ink.

[0036]

Embedded image [Wherein, R ₁ , R ₂ , R ₃ and R ₄ represent the same or different C ₁ -C ₁₀ alkyl groups or aryl groups, and R ₅ and R ₆ represent the same or different C ₁ -C ₁₀ Represents an alkyl group, an aryl group, a hydroxyl group, an amino group, a carboxyl group or an epoxy group, and m and n are the same or different from 0 to 100;
The integer of 0 (especially 1-1000) is shown. ]

[0037]

[Chemical 6] [In formula, m shows the integer of 0-1000 (especially 1-1000). ]

In the above formula (3), R ₁ , R ₂ , R ₃ and R ₄ are preferably the same or different C _{1 to} C ₅ lower alkyl groups or phenyl groups, and m and n are preferably 10 Is an integer from 1 to 100, and R ₅ and R ₆ are preferably the same or different C _{1 to} 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 compounding amount of the compound represented by the above formula (3) or (4) is not particularly limited, but it is preferably 0.001 to 2% by weight in the water-based 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.

The water-based ink of the present invention is particularly useful as a water-based ink for ink jet recording. In this case, the water-based ink can be used for any of a piezoelectric type and a thermal jet type ink jet printer.

Next, a preferred method for producing the above polyester suspension will be described. The above polyester suspension is preferably produced by so-called phase inversion emulsification described below.

Here, the phase inversion emulsification is one selected from the group consisting of a diol component represented by the above formula (1), a divalent or higher polyvalent carboxylic acid, an acid anhydride thereof and a lower alkyl ester thereof. A polyester having an acid value of 3 to 70 KOHmg / g obtained by copolycondensation with the above acid component is dissolved in a solvent together with a dye, a neutralizing agent is added to ionize the carboxyl group in the polyester, and then water is added. After adding
It consists of distilling off the solvent and inversion into an aqueous system.

First, the above polyester is dissolved in a solvent together with a dye. In this case, it is preferable to dissolve the polyester in an amount of 5 to 50 parts by weight with respect to 100 parts by weight of the solvent from the viewpoint of forming a suspension. The solvent is not particularly limited, for example, acetone,
Examples thereof include ketone solvents such as methyl ethyl ketone, diethyl ketone, dipropyl ketone, methyl isobutyl ketone, and methyl isopropyl ketone. Of these, methyl ethyl ketone is preferably used.

Next, a neutralizing agent is added to the above polyester solution. Thereby, the carboxyl groups in the polyester are ionized. The neutralizing agent can be used without any particular limitation as long as it can ionize a carboxyl group in the polyester. Examples of such a neutralizing agent include aqueous solutions of monovalent inorganic salts such as aqueous ammonia, lithium hydroxide, sodium hydroxide and potassium hydroxide, allylamine, isopropylamine, diisopropylamine, ethylamine, diethylamine, triethylamine, and the like. -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-aminopropylpiperazine, N-aminopropyldipiperidipropane, piperazine and the like Amines and the like. In particular, it is preferable to use sodium hydroxide, potassium hydroxide, triethylamine and dimethylethanolamine as the above-mentioned neutralizing agent because the obtained 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. The amount of the neutralizing agent used may be an amount that can at least ionize the carboxyl groups in the polyester.

After the addition of the neutralizing agent, water is added to the solution to cause phase inversion. This produces a suspension of polyester in the aqueous phase. The amount of water to be added is 100 to 3 parts by weight per 100 parts by weight of the solution after the addition of the neutralizing agent.
It is preferably 00 parts by weight. In this case, it is preferable to add water to which the compound represented by the formula (2) is added to the solution, since 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) is added to the above solution, since the generation of bubbles can be suppressed and the surface tension can be adjusted. The addition amount of the compound represented by the above formula (2) is preferably such that it becomes 0.01 to 10% by weight in the finally obtained ink. 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 finally obtained ink.

After the phase inversion is completed, the system is heated under reduced pressure to remove the solvent and a predetermined amount of water, whereby a polyester suspension having a desired concentration is obtained. In the polyester suspension thus obtained, the above polyester is preferably present at a solid content of 1 to 40% by weight, more preferably 5 to 30% by weight.
When the solid content concentration exceeds 40% by weight, the storage stability of the polyester suspension is deteriorated, so the content is preferably within the above range.

The water-based ink of the present invention is particularly useful as an ink-jet recording water-based ink as described above, but can also be used as other inks, for example, inks for writing tools such as general fountain pens, ballpoint pens, felt-tip pens and the like. is there. In the water-based ink of the present invention, the average particle diameter is 0.005 as long as the effect is not impaired.
There is no problem even if a polyester suspension having a thickness other than 0.5 μm is included.

[0049]

EXAMPLES Next, the water-based ink of the present invention will be described in more detail with reference to 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) propane (1050 g), fumaric acid (340 g), and hydroquinone (1.5 g) were placed in a glass 2-liter four-necked flask, and a thermometer, a stainless steel stirring rod, a flow-down condenser and A nitrogen inlet tube was attached to this. The reaction was carried out while stirring at 210 ° C. under a nitrogen stream in a mantle heater. The degree of polymerization was traced from the softening point according to ASTM E28-51T, and the reaction was terminated when the softening point reached 92 ° C. The obtained polyester is a pale yellow solid,
Tg by DSC was 58 ° C. Also, JIS K
The acid value of the polyester based on 0070 is 32 KOH
mg / g, number average molecular weight (in terms of polystyrene by gel permeation chromatography) of 3,000
Met. Next, 150 g of the above polyester and an oily dye (Hodogaya Chemical Co., Ltd., Aizen Spilon Red GEH Special)
40 g and 500 g of methyl ethyl ketone were 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 dye in the methyl ethyl ketone. Then, triethylamine 12.12
g was added to ionize the carboxyl groups in the polyester. Further, 960 g of ion-exchanged water was added dropwise and stirred, and then heated to 40 ° C. under reduced pressure to remove methyl ethyl ketone, and a dye-encapsulated polyester suspension (average particle diameter; 0.08 μm) of 15 wt% aqueous ink was added. Obtained. The average particle size of the suspension is COU
It was measured using an LTER Model N4 SD.

Example 2 A polyester was obtained by the same procedure as in Example 1 except that a 1: 1 mixture of terephthalic acid and 1,2,4-benzenetricarboxylic acid was used instead of fumaric acid in Example 1. It was A dye (manufactured by BASF, manufactured by BASF, N
A 15% by weight aqueous ink of a polyester suspension (average particle diameter: 0.21 μm) in which Eoen Yellow 075) was encapsulated was obtained.

Example 3 Ion-exchanged water 9 containing 3 g of Demol N (dispersant, HLB value 8.51) manufactured by Kao Corporation in place of 960 g of ion-exchanged water in Example 1
A polyester suspension in which a dye (OIL PINK 312, manufactured by Orient Chemical Co., Ltd.) was encapsulated by the same procedure as in Example 1 except that 60 g was used (average particle diameter: 0.
A 04 wt.% 15% by weight aqueous ink was obtained.

Example 4 The same as Example 1 except that 960 g of ion-exchanged water containing 0.12 g of KM-71 (antifoaming agent) manufactured by Shin-Etsu Silicone was used instead of 960 g of ion-exchanged water in Example 1. The polyester suspension in which the dye (OIL BLACK 860, manufactured by Orient Chemical Co., Ltd.) is encapsulated by the operation of (average particle size; 0.12μ
m) 15% by weight aqueous ink was obtained.

Comparative Example 1 A suspension was prepared by changing the suspension preparation conditions so that the average particle size of the polyester suspension in Example 1 was 0.6 μm. As a result, the dispersion stability of the liquid was poor and a considerable amount was obtained. It settled and could not be used as an ink.

[Example 5] -Aqueous ink of polyester suspension obtained in Example 80g-Diethylene glycol 10g-Glycerine 9.8g-Acetylenol EL 0.20g The above components were mixed to obtain a dispersion 5 It was filtered through a micron filter to remove dust and coarse particles to obtain an inkjet ink. Using this ink, printing is performed with a commercially available Canon micro bubble jet printer (model number BJ-10VL) to obtain water resistance, image quality, fixability,
The amount of ink discharged, the print density and the anti-clogging property were evaluated by the following methods. Table 1 shows the results.

<Water resistance> Solid printing was performed on recycled paper for PPC [manufactured by Nippon Kako Kaisha Co., Ltd.], left for 1 hour or more, then immersed vertically in still water for 10 seconds and then pulled up vertically. After air-drying indoors, Macbeth densitometer RD91 was used to determine the optical density of the solid print part and the unprinted white part.
8 (manufactured by Macbeth). <Image quality> After printing alphanumeric characters on recycled paper for PPC [manufactured by Nippon Kako Kaisha Co., Ltd.] and leaving it for 1 hour or more, the sharpness of the characters and the degree of beard-like bleeding caused by the characters with a microscope and visual inspection. (Image quality) was evaluated. ◯: Characters are sharp and there is no beard-like bleeding. Δ: Characters are not sharp and a little bleeding occurs. X: Characters are not sharp and bleeding frequently. BJ Transparency CF301 A
After solid printing on 4) and leaving it for 1 hour or more, an eraser shaving test was conducted to evaluate the degree of peeling of the print. ◯: The print is not peeled at all. Δ: The print was partly peeled off. X: All prints were peeled off. <Ink ejection amount> For printing, solid printing is performed using recycled paper for PPC [manufactured by Nippon Kakoh Paper Co., Ltd.], the weight of the ink cartridge before and after printing is measured, and ink is ejected from the change amount. The amount was calculated. <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). <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 a cap. 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 6 to 8] The same as Example 5 except that the polyester suspension aqueous inks obtained in Examples 2 to 4 were used in place of the polyester suspension aqueous inks obtained in Example 1. An ink jet ink was obtained by the operation of. The same evaluation as in Example 5 was performed using the obtained ink. Table 1 shows the results.

[Comparative Example 2] A commercially available genuine ink (water-based dye-based ink, dye concentration 2.3) used in a Canon micro bubble jet printer (model number BJ-10VL).
(% By weight) was used for the same evaluation as in Example 5. Table 1 shows the results.

[0059]

[Table 1]

As is clear from the results shown in Table 1, the water-based inks of the present invention (Examples 5 to 8) in which the dye was encapsulated in the polyester suspension were the same as those of the ink of the conventional formulation (Comparative Example 2). It can be seen that the water resistance, the image quality, and the fixability are further improved with the print density maintained to some extent. Further, the water-based ink of the present invention (Examples 5 to 8)
Was also excellent in the ink ejection amount and the clogging prevention property.

[0061]

As described above in detail, according to the water-based ink of the present invention, by encapsulating a dye in a polyester suspension having a specific average particle size, printed matter can be obtained without impairing the coloring property of the dye. Water resistance, fixability and image quality are further improved. In particular, by performing the encapsulation by phase inversion emulsification, encapsulation of the dye can be easily and efficiently performed, and the water resistance of the ink is significantly improved. The above-mentioned water-based ink is particularly useful as a water-based 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 (5)

[Claims] 1. A water-based ink comprising a polyester suspension in which a dye is encapsulated, wherein the polyester suspension has an average particle size of 0.005 to 0.5 μm. 2. JIS K007 of the above polyester
The aqueous ink according to claim 1, wherein the acid value based on 0 is 3 to 70 KOHmg / g. 3. The polyester is one or more selected from the group consisting of a diol component represented by the following formula (1), a divalent or higher polyvalent carboxylic acid, an acid anhydride thereof and a lower alkyl ester thereof. The water-based ink according to claim 1 or 2, which is obtained by copolycondensation with an acid component. Embedded image (In the formula, R represents an alkylene group, x and y represent the same or different integers of 1 or more, and the average value of x + y is 2
~ 7. ) 4. A diol component represented by the following formula (1) and one or more acid components selected from the group consisting of divalent or higher polyvalent carboxylic acids, their acid anhydrides and their lower alkyl esters. Acid value obtained by copolycondensation is 3 to 70KO
Dissolving a polyester of Hmg / g in a solvent together with a dye, adding a neutralizing agent to ionize the carboxyl groups in the polyester, and then adding water, and then distilling off the solvent to invert the phase into an aqueous system. The water-based ink according to claim 1, further comprising a polyester suspension obtained by the method. Embedded image (In the formula, R represents an alkylene group, x and y represent the same or different integers of 1 or more, and the average value of x + y is 2
~ 7. ) 5. A water-based ink for inkjet recording, which uses the water-based ink according to claim 1.