JP2000007963A - Water-based ink - Google Patents

Abstract

(57) [Summary] [PROBLEMS] An aqueous system in which printed matter has good bleeding, water resistance, print density and scratch resistance, and in particular, has improved scorching by a head when used in a thermal jet type ink jet printer. Provision of ink. SOLUTION: The aqueous ink of the present invention contains an emulsion of a polyester to which a water-insoluble or poorly water-soluble coloring material is adsorbed, and the polyester comprises a diol component represented by the following formula (1), a trimellitic anhydride, Obtained by co-condensation polymerization of a polycarboxylic acid and / or a derivative thereof. Embedded image

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 system which is excellent in bleeding, water resistance, print density and abrasion resistance of a printed matter, and in particular, has improved head scorching when used in a heat jet type ink jet printer. The present invention relates to a water-based ink useful as an ink for printing.

[0002]

2. Description of the Related Art Water-based inks are often used as inks for printing and writing instruments from the viewpoint of manufacturing and handling. For example, printer devices have become widespread due to the recent development and spread of computers, and water-based inks are used.

In order to prevent nozzles from being clogged with ink, water-soluble dyes which are usually dissolved in water are used for ink used in ink jet printers. However, there is a problem in water resistance of printed matter. Was. Therefore, in order to improve the water resistance of a printed matter, the composition of the ink is important.

In order to improve the water resistance, (A) a pigment may be used (JP-A-4-35972, etc.), or (B)
A non-aqueous liquid medium may be used (JP-A-4-261478), or a water-resistant dye (C) may be used (US Pat. No. 496).
No. 3189), and (D) those using emulsion-polymerized or dispersed-polymerized particles dyed with a dye (JP-A-3-250).
No. 069) has been proposed.

However, when the pigment (A) is used, the saturation of the printed matter may be reduced and clogging in the nozzle may occur. In addition, the fixing property to paper or an OHP sheet, the storage stability of the printed matter, and the like. Had a problem. Further, when the polymer particles (D) were used, it was difficult to perform high-concentration dyeing, and if left for a long period of time, the dye was deposited, resulting in poor liquid stability. In addition, even in the proposals of (B) and (C), an ink which sufficiently satisfies all the required characteristics such as water resistance of the printed matter has not been obtained. Also, if you use a thermal jet ink jet printer to eject ink for a long time,
There is also a problem that components in the ink are oxidized due to excessive heat, and the oxide tends to burn to the printer head.

Accordingly, an object of the present invention is to improve the bleeding and water resistance of printed matter, the print density and the abrasion resistance, and in particular, to improve the scorching of the head when used in a thermal jet type ink jet printer. And water-based inks.

[0007]

SUMMARY OF THE INVENTION The present invention comprises an emulsion of a polyester to which a water-insoluble or poorly water-soluble coloring material is adsorbed, wherein the polyester comprises a diol component represented by the following formula (1): Provided is an aqueous ink obtained by co-condensation polymerization of an acid and a polycarboxylic acid other than trimellitic anhydride and / or a derivative thereof.

[0008]

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Further, the present invention provides an ink for inkjet recording using the above-mentioned water-based ink.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION In the present specification, "adsorbed a water-insoluble or poorly water-soluble coloring material" means that at least a part of the water-insoluble or poorly water-soluble coloring material is adsorbed on micelles formed by the polyester. Or encapsulated in the micelle.

The specific polyester described above includes a diol component represented by the above formula (1) (hereinafter also referred to as a component (a)), a trimellitic anhydride (hereinafter also referred to as a (b) ^* component), Polycarboxylic acids other than trimellitic anhydride and / or derivatives thereof [hereinafter, also referred to as component (b) ^** ]
Are obtained by co-condensation polymerization of By using the polyester, it is possible to improve the water resistance, print density and scratch resistance of the printed matter.

In the component (a), R represents an alkylene group, preferably a linear or branched alkylene group having 1 to 5 carbon atoms, more preferably an ethylene group or a propylene group. The two Rs in the formula (1) may be the same or different. X and Y represent the same or different integers of 0 or more, and the average value of X + Y is 0 to
10, preferably 2 to 4.

In the present invention, as the diol component represented by the above formula (1), R in the formula (1) is an ethylene group or a propylene group, and the average value of X + Y is 2 to 4
Can be preferably used.

The diol component represented by the above formula (1)
One or more of them may be used in combination.

Further, trimellitic anhydride, which is the component (b) ^* , is a component that improves the formability and stability of the emulsion and the amount of coloring material adsorbed. The bonding form of trimellitic anhydride in the polyester is a state in which the cyclic anhydride site in the trimellitic anhydride is opened and incorporated into the polyester chain. By using the acid anhydride instead of trimellitic acid itself, effects such as high reactivity during the polymer synthesis and high formation of the emulsion are exhibited.

Examples of the polycarboxylic acid other than trimellitic anhydride and / or the derivative thereof as the component (b) ^** include, for example, a polycarboxylic acid other than trimellitic anhydride and a polycarboxylic acid. And at least one selected from the group consisting of acid anhydrides and lower alkyl esters thereof.

As the polyvalent carboxylic acid, a divalent or higher carboxylic acid is used. As the lower alkyl ester of these polyvalent carboxylic acids, lower alkyl esters of the above-mentioned polyvalent carboxylic acids and trimellitic anhydride, preferably those having 1 to 4 carbon atoms, are used. Particularly, as the polycarboxylic acid, maleic acid, fumaric acid, itaconic acid, phthalic acid, isophthalic acid, terephthalic acid, succinic acid, n-dodecenylsuccinic acid, divalent carboxylic acid such as dimer acid, or 1,2 , 4
-It is preferred to use benzenetricarboxylic acid.

The polyester is obtained by co-condensation polymerization of the diol component, trimellitic anhydride, and a polycarboxylic acid other than trimellitic anhydride and / or a derivative thereof. There are no particular restrictions on
A known method is used.

The molar ratio of the component (a) to the component (b) ^{* and the} component (b) ^{** is such that the} component (b) ^* is 0.05 to 1 mole per component (a). 0.7 mol is preferable, and 0.1 to 0.5 mol is more preferable. In addition, the component (b) ^{** is used in an} amount of 0.3 to 1 mol per 1 mol of the component (a).
1.2 mol is preferable, and 0.5 to 1.1 mol is more preferable.

Further, a polyester obtained by adding a dimer acid to the above-mentioned polyester (A) and subjecting it to co-condensation polymerization is also preferable. The dimer acid is a substance synthesized by a polymerization reaction of two molecules of an unsaturated fatty acid, and includes, for example, an acyclic dimer acid, a monocyclic dimer acid, and a bicyclic dimer acid. Used. For commercial products, Unidim 22 (trade name, manufactured by Union Cap)
And Hararidimer 250K (trade name, manufactured by Harima Kasei) can be used. By using the dimer acid, the formability and stability of the emulsion are improved, and the coloring material is easily adsorbed. Further, an acyclic dimer acid is particularly preferred from the viewpoint of further improving the formability and stability of the emulsion.

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

JIS of polyester used in the present invention
The acid value based on K 0070 is 3-100 KOHmg
/ G is preferred. The acid value is preferably 3 KOH mg / g or more from the viewpoint of the stability of the emulsion in which the coloring material is adsorbed, and 100 KOH mg / g from the viewpoint of the water resistance of the ink.
The following is preferred. More preferably, the acid value is 3-70.
KOHmg / g, further 10-60KOHmg / g, further 15-55KOHmg / g, further 25-50KOHmg
/ G is preferred.

The acid value is controlled by, for example, changing the addition ratio of the diol component to the polycarboxylic acid and / or a derivative thereof, using a carboxylic acid ester, or blocking the acid with a monohydric alcohol. Can be adjusted.

When used for ink-jet recording inks, the above polyester has a glass transition point (T
g) is preferably 20 ° C or higher, particularly preferably 50 to 150 ° C. 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. The glass transition point of the polyester is preferably within the above preferred range in that the polyester does not solidify at the nozzle of the printer, the nozzle is not clogged, and even when the printed paper is overlapped, the ink does not appear on the paper. . The glass transition point of the polyester can be adjusted, for example, by changing the addition ratio of the diol component and the polycarboxylic acid and / or a derivative thereof. Further, the glass transition point was measured by a differential scanning calorimeter (D
SC).

The above polyester has a number average molecular weight (converted to polystyrene by gel permeation chromatography) of 500 to 100,000, preferably 1 to 100,000.
000-50,000, more preferably 1500-300
00, more preferably 2,000 to 15,000, more preferably 2,000 to 10,000, from the viewpoint of the durability of the ink after printing and the formability of the emulsion.

The above polyester is used in the ink in an amount of 1 to 5
0% by weight, especially 2-30% by weight, is preferred. The amount of the polyester is 1% by weight from the viewpoint of print density.
The above is preferred, and the storage stability of the ink is improved, and in particular, 50% by weight or less from the viewpoint that clogging of the printer head does not occur due to thickening of the ink and aggregation of the emulsion due to evaporation of the ink at the nozzle tip of the ink jet printer. preferable.

Next, the color material will be described. As the coloring material, a coloring material which is insoluble or hardly soluble in water and can be adsorbed by the polyester is used. In this specification, water-insoluble or poorly water-soluble refers to 20
It means that the coloring material does not dissolve in an amount of 10 parts by weight or more with respect to 100 parts by weight of water at a temperature of 0 ° C. Examples of the coloring material include dyes such as oil-soluble dyes and disperse dyes, and pigments. In particular, good adsorption
From the viewpoint of encapsulation, oil-soluble dyes and disperse dyes are preferred.

Particularly preferred specific examples of the above disperse dyes include C.I. I. Disperse Yellow 5 series and the like. Particularly preferred specific examples of the oil-soluble dye include C.I. I. Solvent Black 3 series.

From the viewpoint that the dye is efficiently adsorbed on the polyester by phase inversion emulsification described below, a solvent,
For example, 20 g / l or more, preferably 4 g / l
0 g / l or more, more preferably 50 g / l or more, still more preferably 60 g / l or more, and still more preferably 100 to 60 g / l.
A dissolution of 0 g / l is desirable.

On the other hand, as the pigment, a pigment which can be adsorbed by the polyester can be used.
In particular, azo pigments, phthalocyanine pigments, anthraquinone pigments, and carbon black pigments are preferred. In the aqueous ink of the present invention, a water-soluble dye such as a direct dye, an acid dye or a basic dye may be used in combination.

The above coloring material is contained in the water-based ink of the present invention in an amount of 1 to 1.
A blend of 30% by weight, especially 1.5 to 25% by weight is preferred. The amount of the coloring material is 1% by weight from the viewpoint of print density.
The above are preferred, and from the viewpoint of the print density and the stability over time of the particle size of the emulsion are improved, the average particle size is reduced, and the dispersion stability of the emulsion itself is improved.
It is preferably 0% by weight or less.

The emulsion having the coloring material adsorbed thereon preferably has an average particle size of 0.5 to 500 nm. The average particle size of the emulsion is preferably 0.5 nm or more from the viewpoint that ink bleeding does not occur, and is preferably 500 nm or less from the viewpoint of the dispersion stability of the emulsion itself. When the average particle diameter is 0.5 to 300 nm, particularly 1 to 200 nm, and more preferably 10 to 100 nm, good results can be obtained in terms of emulsion formability and stability. The average particle diameter can be adjusted, for example, by changing the conditions for phase inversion emulsification described below. The average particle diameter of the polyester emulsion can be measured using a COULTER Model N4SD (trade name) or using an electron microscope (TEM, SEM).
Sought by observation.

The water-based ink of the present invention contains water (preferably ion-exchanged water) as a medium, and contains not only a polyester emulsion having the coloring material adsorbed thereon but also water-soluble alkyl glycine and various additives. Agents, for example, wetting agents such as polyhydric alcohols, dispersants, silicone-based antifoaming agents, cationic, anionic or nonionic surfactants, etc., surface tension modifiers, ultraviolet absorption such as benzotriazole and benzophenone. Agents, light stabilizers such as hindered phenol and hindered amine, fungicides such as chloromethylphenol and / or chelating agents such as EDTA,
Further, it may contain an oxygen absorbent such as a sulfite.

In the water-based ink of the present invention, water (preferably ion-exchanged water) is 50 to 98% by weight, particularly 5 to 98% by weight.
A blending ratio of 5 to 95% by weight, more preferably 60 to 90% by weight is preferred.

By using the above-mentioned water-soluble alkyl glycine in the water-based ink of the present invention, the liquid stability and dischargeability of the ink can be improved. 2 for 1 liter of water
Alkyl glycine that dissolves in an amount of 0 g or more, particularly 200 g or more, is preferable, and examples of the alkyl glycine include a compound represented by the following formula (2).

[0036]

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Examples of the alkyl group having 1 to 5 carbon atoms represented by Ra in the above formula (2) include methyl, ethyl, propyl, isopropyl and the like. Further, as the alkyl glycine, methyl glycine in which Ra is a methyl group is particularly preferable in view of high solubility in water. When using the above-mentioned alkylglycine, one or more of these compounds may be used.

The alkyl glycine is contained in the ink in an amount of 0.5 to 50% by weight, particularly 2 to 35% by weight, and more preferably 3 to 2% by weight.
A 5% by weight formulation is preferred. The compounding amount of the above alkyl glycine is preferably 0.5% by weight or more from the viewpoint of the moisturizing effect and from the viewpoint that the liquid stability is improved without drying with the inkjet nozzle, and the ink viscosity is reduced, and the ink ejection property is improved. The content is preferably 50% by weight or less from the viewpoints that the printing quality is good, the drying of the printed matter is quick, and the fixing property is improved.

Examples of the wetting agent include glycols such as ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol and polyethylene glycol; glycerin; ethers of polyhydric alcohols such as diethylene glycol monobutyl ether; acetates; Glycol: glycine, methylglycine, leucine, proline, ε-amino-n-
One or more amino acids such as caproic acid, alanine and phenylalanine can be used. The compounding amount of these wetting agents is 0.1 to 50% by weight, particularly 0.1 to 50% by weight in the aqueous ink.
30% by weight is preferred. The blending amount of the wetting agent is preferably 0.1% by weight or more from the viewpoint of the wetting effect, and 50% by weight from the viewpoint that the ink is easily dried and printing bleeding does not occur.
The following is preferred.

As the dispersant, for example, one or more known anionic surfactants, cationic surfactants, amphoteric surfactants, nonionic surfactants, and polymer dispersants can be used. Above all, β-naphthalenesulfonic acid formalin condensate is particularly preferred from the viewpoint of reducing the average particle size of the emulsion and improving the dispersion stability of the emulsion.

When the β-naphthalenesulfonic acid formalin condensate salt has an HLB value of 5 to 15, the dispersing effect of the polyester adsorbing the coloring material is exhibited, so that the average particle diameter due to the aggregation of the polyester in the emulsion is obtained. The effect of suppressing the increase in the thickness is advantageous.

As the β-naphthalenesulfonic acid formalin condensate, commercially available products can also be used. For example, Kao Corporation dispersant Demol SNB, MS, N, SSL,
ST, P, and C (product names).

The above-mentioned dispersant is usually contained in an aqueous ink at a concentration of 0.1%.
It is blended in an amount of from 0.01 to 10% by weight. The amount of the dispersant is preferably 0.01% by weight or more from the viewpoint that it is easy to reduce the particle size of the emulsion, and from the viewpoint that the average particle size of the emulsion is reduced, the stability is improved, and gelation is not performed. 1
It is preferably 0% by weight or less. The amount of the dispersant is more preferably 0.05 to 5% by weight, most preferably 0.1 to 5% by weight.
１1% by weight.

As the defoaming agent, a silicone compound is particularly preferred from the viewpoint of suppressing the generation of bubbles during the preparation of the ink and adjusting the surface tension of the ink.

Examples of the silicone-based antifoaming agent include KF96 series (trade name) manufactured by Shin-Etsu Silicone Co., Ltd.
And the like.

The amount of the silicone-based antifoaming agent is preferably 0.001 to 2% by weight in the aqueous ink of the present invention. The compounding amount of the silicone-based antifoaming agent is preferably 0.001% by weight or more from the viewpoint that bubbles are hardly generated at the time of preparing the ink and small bubbles are easily removed from the ink. The content is preferably 2% by weight or less from the viewpoint that printing quality is improved without generation. The amount of the silicone-based antifoaming agent is more preferably 0.005 to 0.5% by weight.

As the surface tension adjusting agent, the above-mentioned silicone-based antifoaming agents and various surfactants of cationic, anionic or nonionic type can be used. In particular, ethylene oxide compounds of alkylphenols,
An ethylene oxide adduct of acetylene glycol is preferred in terms of suppressing generation of bubbles, easily adjusting the surface tension of the ink, ink ejection properties, less bleeding, and non-uniform print density.

When using the above-mentioned surface tension adjuster, one or more of these compounds can be used, and it is desirable to add 0.005 to 15% by weight in the aqueous ink. The blending amount of the surface tension modifier is preferably 0.005% or more from the viewpoint that the above characteristics can be exhibited, and from the viewpoints of improving printing quality without causing bleeding and uneven printing density, and from the viewpoint of ink liquid stability. It is preferably at most 15% by weight.

The viscosity of the water-based ink of the present invention is 20
At 0 ° C, 0.5 to 8 cps, particularly 1 to 5 cps, and more preferably 1 to 3 cps is preferable. 20 ° C. of the water-based ink of the present invention
The viscosity is preferably 0.5 cps or more from the viewpoint that ink bleeding does not occur and ink does not leak from the print head nozzle.The viscosity as the ink for inkjet is kept low, and the ink supply to the print head is It is preferably 8 cps or less from the viewpoint that the printing becomes smooth, no ejection failure occurs, and the print quality is improved without blurring. In order to make the viscosity of the aqueous ink of the present invention within the above range,
For example, means such as adjustment of the concentration of the coloring material, adjustment of the concentration and molecular weight of the polyester, addition of additives such as various surfactants and surface tension adjusting agents, selection of the wetting agent, and adjustment of the amount of the used are used. I just need. The above viscosity is measured by E-type viscometer (VISCONIC ELD) manufactured by Tokyo Keiki Co., Ltd.
It can be measured by a rotary vibration type viscometer (Viscomate VM-100) manufactured by Nikkato Tokyo Branch.

Surface tension of water-based ink of the present invention (20 ° C.)
Is preferably in the range of 25 to 50 dyne / cm. The surface tension is preferably 25 dyne / cm or more from the viewpoint that ink bleeding does not occur, print quality is improved, and when used as ink for inkjet recording, ink does not leak from nozzles of the inkjet printer. The ink drying rate is preferably 50 dyne / cm or less from the viewpoint that the ink drying speed is fast, the color mixing of the ink on the print, the print head contamination does not occur, the ink supply to the nozzles is smooth, and the ink discharge and the print quality are improved. The surface tension is more preferably 28 to 43 dyne / cm.
Further, when the color tone is magenta, cyan, and yellow, 2
8 to 40 dyne / cm, especially 28 to 36 dyne / c
m, 28 to 40 dyne / c when the color tone is black
m is preferred. In order to make the surface tension of the aqueous ink of the present invention within the above range, for example, adjustment of the concentration of the coloring material, adjustment of the concentration and molecular weight of the polyester, addition of a surface tension adjuster, etc.
Means such as selection of a wetting agent may be used. The surface tension was measured using an automatic surface tension meter (CBVP) manufactured by Kyowa Interface Science Co., Ltd.
-Z type).

Next, a preferred method for producing the water-based ink of the present invention will be described. The aqueous ink of the present invention is produced by a phase inversion emulsification method or a forced emulsification method, but the phase inversion emulsification method is preferred from the viewpoint of emulsion stability.

The phase inversion emulsification is carried out by co-condensation of a diol component represented by the above formula (1), trimellitic anhydride, and a polycarboxylic acid other than trimellitic anhydride and / or a derivative thereof. The resulting polyester (having an acid value of preferably 3 to 100 KOH mg / g) is added to a solvent together with the coloring material, a neutralizing agent is added to ionize the carboxyl groups in the polyester, and then water is added. After that, the solvent is distilled off and the phase is changed to an aqueous phase.

First, the polyester is added to a solvent together with the coloring material. In this case, it is preferable to add 5 to 50 parts by weight of the polyester based on 100 parts by weight of the solvent from the viewpoint of emulsion formation. As the solvent, for example, methyl ethyl ketone and tetrahydrofuran are preferable.

Next, the polyester, the coloring material,
A neutralizing agent is added to the mixture with the above solvent to ionize the carboxyl groups in the polyester. The neutralizing agent can be used without particular limitation as long as it can ionize a carboxyl group in the polyester. In particular, sodium hydroxide, potassium hydroxide, triethylamine and dimethylethanolamine are used as emulsion particles. It is preferable from the viewpoint of reducing the particle size and the stability of the emulsion. Of these, sodium hydroxide and potassium hydroxide are also preferred in view of the heat resistance of the emulsion. The amount of the neutralizing agent used may be such that at least the carboxyl group in the polyester can be ionized.

After the addition of the neutralizing agent, when water is added to the mixture to cause phase inversion, an emulsion of polyester is formed in the aqueous phase. The amount of water to be added is
100 to 300 parts by weight based on parts by weight is preferred. In this case, it is preferable to add the above β-naphthalenesulfonic acid formalin condensate salt to the above mixed solution, because the average particle diameter of the emulsion can be reduced. Further, when the silicone-based antifoaming agent or the surface tension adjusting agent is added to the mixed solution, it is possible to suppress generation of bubbles and adjust the surface tension.

After the phase inversion was completed, the system was heated under reduced pressure. By removing the solvent and a predetermined amount of water in the mixture, the coloring material having a desired concentration was adsorbed. An emulsion of the polyester is obtained. In preparing the water-based ink of the present invention, it is preferable to remove coarse particles. For example, the above-mentioned ink is filtered under pressure by a filter or processed by a centrifugal separator, and is subjected to 2,000 nm.
Or more, preferably 1000 nm or more, more preferably 5 nm or more.
By removing particles having a size of 00 nm or more, an ink without clogging can be obtained.

The water-based ink of the present invention is particularly useful as an ink for ink-jet recording. For example, it can also be used as an ink for writing implements such as general fountain pens, ball-point pens, and felt-tip pens. In addition, p of the aqueous ink of the present invention
As H, pH is used to ensure the stability of the emulsion.
= 5 to 12, preferably 5.5 to 10.

[0058]

EXAMPLES Next, the effectiveness of the water-based ink of the present invention will be illustrated by examples.

Example 1 90 g of a dimer acid mixture containing 684 g of a diol component represented by the following formula (A), 30% by weight of a dimer acid compound and 10% by weight of a dimer acid compound, 270 g of fumaric acid, and 0.6 g of hydroquinone
And 1.7 g of dibutyltin oxide were placed in a 2 liter four-necked flask, and a thermometer, a stirring rod, a falling condenser, and a nitrogen inlet tube were attached. After reacting for 8 hours while stirring at 210 ° C. under a nitrogen stream in a mantle heater,
120 g of trimellitic anhydride was added for further reaction, and the reaction was terminated when the acid value reached 58 KOHmg / g. The obtained polyester (hereinafter, referred to as “polyester”) was a pale yellow solid, had a glass transition point of 74 ° C. by DSC and a softening point of 130 ° C. Also, J
The acid value of the polyester based on IS K 0070 is 5
8 KOH mg / g, and the number average molecular weight (in terms of polystyrene by gel permeation chromatography) is 5
500.

[0060]

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Next, 150 g of the above polyester and oil-soluble dye a (Oil Chemical, 0IL BLACK 8)
60) 60 g and 500 g of tetrahydrofuran were put into a separable flask, and after purging with nitrogen, the polyester and the oil-soluble dye a were dissolved in tetrahydrofuran. Subsequently, 15.20 g of dimethylethanolamine
Was added to ionize the carboxyl groups in the polyester. Further, after dropping 960 g of ion-exchanged water,
Tetrahydrofuran was removed by heating to 40 ° C. under reduced pressure to obtain an aqueous ink of a polyester emulsion (average particle diameter: 40 nm, 20% by weight) to which the dye was adsorbed.

Example 2 A diol component 73 represented by the following formula (B) was used instead of the diol component used in Example 1.
0 g, fumaric acid 40 g, terephthalic acid 320
g, 85 g of dimer acid and 115 g of 1,2,4-benzenetricarboxylic acid were obtained in the same manner as in Example 1 to obtain a polyester (hereinafter referred to as “polyester”) (acid value: 52 KOH mg / g, glass transition point). : 65 ° C,
(Number average molecular weight: 6500).

[0063]

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Using the above polyester, the dye was adsorbed in the same manner as in Example 1 except that an oil-soluble dye b (manufactured by Orient Chemical Co., Ltd., OIL SCARLET 308) was used instead of the oil-soluble dye a as a coloring material. Emulsion of polyester (average particle diameter: 46 nm, 2
0% by weight) of an aqueous ink.

[Example 3] Instead of 960 g of ion-exchanged water used in Example 1, ion-exchanged water 9 containing 3 g of Demol N (dispersant, HLB value 8.51) manufactured by Kao Corporation.
Using 60 g, as a coloring material, an oil-soluble dye c (manufactured by Orient Chemical, OIL YELLOW) instead of the oil-soluble dye a
A water-based ink of a polyester emulsion (average particle diameter: 33 nm, 20% by weight) to which a dye was adsorbed was obtained in the same manner as in Example 1 except that 129) was used.

Example 4 The same procedure as in Example 1 was repeated except that 40 g of a pigment (phthalocyanine blue) was used in place of the oil-soluble dye a used in Example 1, to thereby prepare an emulsion of a polyester having a pigment adsorbed thereon. Average particle size: 72n
m, 20% by weight).

Example 5 80 g of an aqueous ink of the polyester emulsion obtained in Example 1 5 g of diethylene glycol 10 g of N-methylglycine 4.8 g of glycerin Acetylenol EL (trade name; Kawaken Fine Chemical Co., Ltd.) 0.20 g The above components were mixed, and the resulting dispersion was filtered through a 5-micron filter to remove coarse particles to obtain an ink for inkjet recording. For this ink, while evaluating the colorant introduction amount and liquid stability by the following method,
Using this ink, printing was performed using a commercially available Color Bubble Jet Printer manufactured by Canon (model number BJ-250J), and water resistance, print density, scorching of ink, bleeding and scratch resistance were evaluated by the following methods. Table 1 shows the results.

<Amount of Coloring Material Introduced> 10 g of the coloring material-adsorbed emulsion was dissolved in 40 g of toluene, and the absorbance of the solution was measured to determine the amount of the coloring material adsorbed on the emulsion. The amount of the coloring material introduced can also be calculated from the amount of the coloring material / polymer at the time of preparing the emulsion. <Liquid stability> The evaluation ink was placed in a constant temperature room at 50 ° C. for one month, and the particle size distribution before and after that was measured by a Coulter counter. ◎: No change in particle size distribution at all, average particle size of 100 nm or less in monodispersed system ○: Subtle change in particle size distribution, but average particle size of 100 nm or less in monodispersed system △: Particle size distribution A polydisperse system having a distribution of two peaks or more and having an average particle size of 200 nm or less.
After solid printing was carried out using, the sample was allowed to stand for 1 hour or longer, then dipped vertically in still water for 10 seconds, and pulled up vertically. After natural drying in a room, the optical character density of the white portion where no printing was performed was measured with a Macbeth densitometer RD918 (manufactured by Macbeth).

<Print Density> Solid printing was performed using recycled paper for PPC [manufactured by Nippon Kaishi Paper Co., Ltd.]
After naturally drying for a time, the optical density was measured with a Macbeth densitometer RD918 (manufactured by Macbeth).

<Ink Burning> After application of 2 million pulses, the state of burning of the printer head was determined by microscopic observation. ：: There is no scorching on the printer head. Δ: The printer head is partially scorched. X: The entire print head is scorched. <Bleeding> Recycled paper for PPC [manufactured by Nippon Kaishi Paper Co., Ltd.]
After printing an alphanumeric character and leaving it for one hour or more, the sharpness of the character and the degree of mustache-like bleeding generated from the character were evaluated with a microscope and visually. ：: The characters are sharp and have no whisker-like bleeding. Δ: The characters are not sharp and bleeding occurs a little. X: The character is not sharp and has much bleeding. <Scratch resistance> Glossy paper for inkjet (Epson,
Solid printing on photo quality paper MJA4SP3), fixing an eraser (width 18.5mm) at 45 ° inclination, placing a load of 1kg on it, rubbing it 5 times on the solid printing surface, and the state of the printing surface at that time Was visually observed. ：: No shaving at all, and the gloss is unchanged. Δ: There is a part that has been shaved, but the gloss remains unchanged. ×: Scratching occurs on the entire surface and gloss is lost.

Examples 6 to 8 Ink jet recording was performed in the same manner as in Example 5 except that the aqueous inks obtained in Examples 2 to 4 were used instead of the aqueous ink obtained in Example 1. Ink was obtained. The same evaluation as in Example 5 was performed using the obtained ink. Table 1 shows the results.

Comparative Example 1 An ink having the following composition was obtained using a water-soluble dye commonly used in ink jet recording inks.・ C. I. Acid Yellow 4g ・ Diethylene glycol 7.5g ・ Glycerin 7.5g ・ Water 80.60g ・ Acetyleneol EL 0.40g That is, the above components were mixed for 12 hours using a ball mill, and the obtained dispersion was filtered with a 5 micron filter. After filtration, coarse particles were removed to obtain an ink. The same evaluation as in Example 5 was performed using the obtained ink. Table 1 shows the results.

Comparative Example 2 (Preparation of Pigment Dispersion) ・ Styrene-acrylic acid copolymer 3 parts by weight ・ Triethanolamine 7 parts by weight ・ Ion-exchanged water 75 parts by weight The above components were mixed and heated to about 70 ° C. After heating to dissolve the styrene-acrylic acid copolymer, 15 parts by weight of a pigment (phthalocyanine blue) was added, and a dispersion treatment was performed under the following conditions. -Dispersing machine: Sand mill (manufactured by Yasukawa Seisakusho)-Grinding media: Glass beads (1.7 mm diameter)-Filling rate of media: 1.5 times (weight)-Dispersing time: 2 hours After dispersion, glass beads were removed and 5 µm After removing coarse particles with a membrane filter, a pigment dispersion (average particle size;
150 nm). (Manufacture of ink)-50 parts by weight of the above pigment dispersion-6 parts by weight of glycerin-11.5 parts by weight of diethylene glycol-10 parts by weight of polyethylene glycol (PEG300)-22.5 parts by weight of ion-exchanged water A pigment ink is manufactured from the above components. Then, the same evaluation as in Example 5 was performed. Table 1 shows the results.

Comparative Example 3 The following polyester was used in place of the polyester used in Example 1, except that
The same operation as in Example 1 was performed. However, most of the coloring material (oil-soluble dye a) used for the preparation precipitated and settled together with some polyester. Therefore, the precipitate was removed by filtration to obtain an ink containing a polyester emulsion (average particle size: 40 nm, 10% by weight) to which a coloring material was adsorbed. In an autoclave equipped with a polyester synthesis thermometer and a stirrer, 130 parts by weight of dimethyl terephthalate, 56 parts by weight of dimethyl isophthalate, 6 parts by weight of dimethyl sodium sulfoisophthalate, 159 parts by weight of ethylene glycol, and 30 parts by weight of tricyclodecane dimethanol 30 Parts by weight and 0.1 part by weight of tetrabutoxytitanate,
The ester exchange reaction was performed by heating at a temperature of 30 ° C. for 120 minutes. Thereafter, the temperature was raised to 240 ° C., the pressure applied to the reaction solution was set to 1 to 10 mmHg, and when the softening point reached 100 ° C., the reaction was terminated, and a polyester was synthesized.
(Pale yellowish white solid, glass transition point is 50 ℃)

Next, the same procedure as in Example 5 was carried out except that the above-mentioned ink was used in place of the aqueous ink of Example 1 and mixed with the following composition.
By the same operation as described above, an ink jet recording ink was obtained. The same evaluation as in Example 5 was performed using the obtained ink. Table 1 shows the results. (Blending)-87 g of the above ink-10 g of diethylene glycol-2 g of glycerin-1 g of acetylenol EL

[0076]

[Table 1]

As is evident from the results shown in Table 1, in the aqueous ink of the embodiment (the present invention) containing the emulsion of the specific polyester to which the water-insoluble or poorly water-soluble coloring material is adsorbed, the amount of the coloring material introduced is reduced. It can be seen that the bleeding, the water resistance, and the scratch resistance of the printed matter are further improved while the print density is maintained at about the same level as or higher than that of the ink of the conventional formulation (Comparative Example 1). Further, it can be seen that the water-based ink of the example improves the scorching of the head. Also,
Conventional pigment ink (Comparative Example 2) and ink using a polyester other than the polyester according to the present invention (Comparative Example 3)
Was high in water resistance but low in print density and poor in scorching of the head.

[0078]

According to the water-based ink of the present invention, the amount of coloring material introduced is improved, the bleeding and water resistance of printed matter, the print density and the abrasion resistance are improved, and the ink is used in a thermal jet type ink jet printer. Burning at the time of the head is improved. Further, by performing the above-mentioned adsorption by phase inversion emulsification, it is possible to easily and efficiently adsorb a water-insoluble or poorly water-soluble coloring material, and the water resistance and printing density of the ink are further improved.

Claims (2)

[Claims] 1. An emulsion comprising a polyester to which a water-insoluble or poorly water-soluble coloring material is adsorbed, wherein the polyester is other than a diol component represented by the following formula (1), trimellitic anhydride, and trimellitic anhydride: A water-based ink obtained by co-condensation polymerization of a polycarboxylic acid and / or a derivative thereof. Embedded image 2. An ink for inkjet recording using the water-based ink according to claim 1.