JP2003171584A - Inkjet aqueous ink composition and ink set - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet aqueous ink composition which is hard to spread, excels in water resistance and, simultaneously, enables high quality level printing even in high-speed printing. <P>SOLUTION: The inkjet aqueous ink composition comprises (a) a coloring material to be selected from dyes and (b) a water dispersion polyester resin having a weight average molecular weight of ≤30,000, a hydroxy number of ≤13, and an acid value of ≤20, and a particle diameter of ≤200 nm. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention improves water resistance, which is suitably used for ink jet recording in which ink is ejected and jetted by mechanical energy and / or thermal energy to record on a recording material, In addition, the present invention relates to a water-based inkjet ink composition and ink set having improved bleeding.

[0002]

2. Description of the Related Art The ink jet recording method forms a droplet of ink by using a mechanical action and / or a thermal action and deposits it on a recording material (medium) such as paper to form a dot. This is a method of recording an image. The inkjet recording method is a typical non-impact recording method of recording an image on a medium in response to a digital signal from a personal computer or the like. In addition, since this inkjet recording method does not include processes such as development and fixing that are required in recording methods such as electrophotography, it is easy to downsize the apparatus, and at the same time, recording at high speed and with low noise is possible. It is possible. Further, such a recording method called an on-demand type has been widely used in recent years as an output device for office and home personal computers because the recording device is relatively inexpensive and can easily be colorized. Came.

The most desired characteristic of the ink jet recording method is high-speed and stable high-quality printing similar to electrophotography. On the other hand, it is desired to improve the water resistance and the light resistance of the current ink. Therefore, as a method of improving the water resistance of ink, an approach from a coloring material has been made. For example, JP-A-3-15338
Japanese Patent Publication No. 5 discloses a method of reacting and fixing a dye and a medium by using a reactive dye having a reactive moiety bonded to a chromophore. However, this method requires extremely complicated steps such as a treatment step with an alkaline solution and a heating step. Further, the reactive dyes disclosed in the above publications are relatively unstable, and hydrochloric acid produced by the reaction has a drawback that they damage the printer head and the formed image, that is, the medium.

Further, Japanese Patent No. 3178919 discloses a method of improving water resistance by using an ink in which a boron polymer, a dye and a specific penetrant are combined. Although this method improves bleeding, it has a practical problem that the water resistance of the printed matter decreases because the ionicity of the boron polymer is maintained.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a water-based ink composition for inkjet which is resistant to bleeding, excellent in water resistance, and capable of high-quality printing even in high-speed printing.

[0006]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that by blending a coloring material selected from a specific dye and a specific water-dispersed polyester resin. The inventors have found that it is possible to provide a water-based ink composition for inkjet which is resistant to bleeding, has excellent water resistance, and enables high-quality (high-quality) printing even in high-speed printing, and has completed the present invention.

Thus, according to the present invention, (a) a colorant selected from dyes, and (b) a weight average molecular weight of 30.
000 or less, a hydroxyl value of 13 or less, an acid value of 20 or less, and a water-dispersed polyester resin having a particle diameter of 200 nm or less (hereinafter referred to as "ink composition"). ) Is provided.

Further, according to the present invention, an ink set obtained by combining the above ink compositions containing a cyan dye, a magenta dye and a yellow dye separately as coloring materials, and further combining the above ink composition containing a black dye. Ink set provided.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION An ink composition satisfying the above conditions at a minimum can perform printing with less bleeding on a medium and excellent water resistance. It is considered that this is obtained by the water-dispersed polyester resin acting as a binder.

As the coloring material used in the present invention, there is basically no particular problem as long as it is a water-soluble dye. Specific examples include acid dyes, direct dyes, and reactive dyes. Among these, those having excellent water resistance and light resistance and those having excellent safety can be preferably used.

The color material used in the present invention is indicated by the color index number (CI) of the dye for each color system. Examples of blue (cyan) include acid blue 7, 9, 29, 45, 92, 249 direct blue 1, 2, 6, 15, 22, 25, 7
1, 76, 79, 86, 90, 98, 163, 165
199,202 Reactive Blue 1,2,7,14,15,23,3
2,38,41,63,80,95, of which at least one cyan dye selected from Acid Blue 7, Acid Blue 9 and Direct Blue 199 is particularly preferable.

Examples of red colors (magenta) include Acid Red 1, 8, 13, 14, 18, 26, 2
7,35,37,42,52,82,87,89,9
2,97,106,111,114,115,134,
186,249,254,289 Direct Red 1,4,9,13,17,20,2
8, 31, 39, 80, 81, 83, 89, 225, 2
27 Direct Orange 26, 29, 62, 102 Reactive Red 1, 14, 17, 25, 26, 3
2,37,44,46,55,58,60,66,7
4, 79, 96, 97, 141, 147, 180, 18
1, among these, at least one magenta dye selected from Acid Red 52, Acid Red 289, Reactive Red 58, Reactive Red 141 and Reactive Red 180 is particularly preferable.

Examples of yellow (yellow) colors include Acid Yellow 1, 7, 17, 23, 42, 44, 7
9,142 Direct Yellow 1,12,24,26,33,4
4,50,86,120,132,142,144 Reactive Yellow 1,5,11,13,14,2
0, 21, 22, 25, 40, 47, 51, 55, 6
5,67, and among these, Acid Yellow 17,
At least one yellow dye selected from Acid Yellow 23 and Direct Yellow 86 is particularly preferable.

As the black type (black), for example, hood black 2 direct black 19, 22, 32, 38, 51, 5
6,71,74,75,77,154,168,171 Reactive Black 3,4,7,11,12,17, among these, at least one selected from Food Black 2 and Direct Black 154
Particular black dyes are particularly preferred.

The blending amount of the coloring material is not particularly limited, but it is generally used within the range of each dye, which can be stably dissolved at room temperature. The blending amount is preferably in the range of 0.1 to 10% by weight. When the blending amount of the coloring material is less than 0.1% by weight, it is difficult to obtain the required color tone and contrast, which is not preferable. In addition, the blending amount of coloring material is 10% by weight.
If it exceeds, clogging is likely to occur in the nozzle, which is not preferable.

The water-dispersed polyester resin used in the present invention has a weight average molecular weight of 30,000 or less, a hydroxyl value of 13 or less, an acid value of 20 or less, and a particle diameter of 200 nm or less (preferably 50 nm or less). By including this water-dispersed polyester resin, the ink composition can improve the water resistance after printing. When the weight average molecular weight is 30,000 or less, the viscosity is low and the dispersed particle size is easily controlled, which is preferable. Also, in terms of the constituent components of the resin,
The hydroxyl value is preferably 13 or less and the acid value is preferably 20 or less.

If the glass transition temperature (Tg) of the water-dispersed polyester resin exceeds 70 ° C., the elongation at break (elongation at break) tends to be small and the scratch resistance is deteriorated.
Is preferably 70 ° C. or lower. In addition, when printing on a medium such as inkjet-dedicated paper having a coating layer such as glossy paper, a Tg of 70 ° C. or less is preferable because the low Tg water-dispersed polyester resin tends to adhere to the medium. Is preferred. As such a water-dispersed polyester, a commercially available product satisfying the above-mentioned conditions can be used, and examples thereof include Bayronal series manufactured by Toyobo Co., Ltd.

The ink composition of the present invention preferably contains at least one organic solvent, and the organic solvent is a water-soluble organic solvent having a vapor pressure lower than that of water at the environmental temperature at which the ink composition is used. Is preferred. By including the water-soluble organic solvent, the drying property of the ink can be controlled and the clogging of the nozzle can be eliminated. Here, the “use environment temperature of the ink composition” means an operation environment temperature or a storage environment temperature of an inkjet recording apparatus using the ink composition.

Specific examples of the organic solvent are shown below, but the invention is not limited thereto. Amides: dimethylformamide, dimethylacetamide, etc. Glycols: polyethylene glycol, polypropylene glycol, ethylene glycol, thiodiglycol, propylene glycol, triethylene glycol,
Diethylene glycol, 1,2,6-hexanetriol, etc.

Lower alkyl ethers of polyhydric alcohols: ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, ethylene glycol monobutyl ether, carbitol (diethylene glycol monoethyl ether), triethylene glycol monobutyl ether (TEGBE), propylene glycol monoethyl ether, Tetraethylene glycol monomethyl ether, ethylene glycol monophenyl ether, etc.

Alcohols: 1,5-pentanediol, 1,4-butanediol, 1,3-propanediol, glycerin, etc. Sulfur-containing substances: sulfolane, dimethylsulfoxide, etc. Polyfunctional substances: dimethylaminoethanol, diethylaminoethanol, tri Nitrogen-containing substances such as ethanolamine and morpholine: 2-pyrrolidone, N-methylpyrrolidone,
ε-caprolactam, γ-butyrolactone, etc.

Among these, polyethylene glycol, diethylene glycol, ethyl carbitol, TE
GBE, 1,5-pentanediol, glycerin, 2-
At least one water-soluble organic solvent selected from pyrrolidone and N-methylpyrrolidone is preferred, and at least one water-soluble organic solvent selected from diethylene glycol, TEGBE, glycerin and 2-pyrrolidone is particularly preferred. Discharge performance can be improved by blending these water-soluble organic solvents.

The compounding amount of the organic solvent is in the range of 1 to 50% by weight, preferably 1 to 40% by weight, more preferably 10 to 40% by weight. If the blending amount of the organic solvent is less than 1% by weight, the moisture retention of the ink is insufficient and the solid content is dried and solidified at the nozzle, which is not preferable. Further, when the content of the organic solvent is more than 50% by weight, the content of water becomes low, and when printed, bleeding occurs on the medium or the drying property is significantly deteriorated, which is not preferable. .

It is preferable that the ink composition of the present invention further contains a nonionic surfactant, and the blending amount thereof is not less than the critical micelle concentration. As nonionic surfactants,
For example, the compounds represented by Chemical Formulas 1 to 4 may be mentioned.

[0025]

[Chemical 1]

The coefficients m, n, x and y in Chemical Formulas 1 to 4 are as shown below. n: integer of 0 to 50, preferably integer of 3 to 30 m: integer of 0 to 50, preferably integer of 3 to 30 x: integer of 1 to 50, preferably integer of 3 to 15 y: 1 to 15 Of integers, preferably 2-10

The content of the nonionic surfactant is preferably equal to or higher than the critical micelle concentration of the nonionic surfactant. Usually about 0.05 to 4% by weight, preferably 0.5
It is about 2% by weight. When the blending amount of the nonionic surfactant is within the above range, the function of the surfactant can be exhibited and the wettability with respect to the hydrophobic surface can be improved. That is, the wettability with respect to the printer member becomes good, and the ink supply becomes smooth.

Additives may be added to the ink composition of the present invention as needed in order to impart desired physical properties. Examples of such additives include antifungal agents, pH adjusters, chelating agents, preservatives, and ultraviolet absorbers.

Examples of the fungicide include sodium dehydroacetate, sodium benzoate, sodium sorbitate and the like. Examples of pH adjusters include triethanolamine, sodium hydroxide, sodium carbonate, sodium nitrate, potassium nitrate and the like.

In the ink composition of the present invention, for example, a dye is added to water and stirred at room temperature to completely dissolve the dye, and then a water-dispersed polyester resin, an organic solvent and other additives are sequentially added. Finally, add the surfactant and
After stirring for a period of time, it is obtained by filtering with a filter of the desired size.

The ink composition of the present invention can be prepared by dissolving or dispersing the constituents in water as described above. The water used is high-purity water having a low content of impurities. preferable. Impurities contained in water are not preferable because they interfere with the action of surfactants (for example, chemical formulas 1 to 4) and make it difficult to sufficiently exhibit the originally expected effects of the present invention. The conductivity can be used as an index of water purity, and the index is conductivity 250 μS / c.
m or less.

Although various physical properties of the ink composition of the present invention can be controlled appropriately, according to a preferred embodiment of the present invention, the viscosity (25 ° C.) of the ink composition is 20 mPa · sec or less, preferably 15 mPa · s.・ It is less than a second. When the viscosity of the ink composition is within the above range, it is possible to ensure the ejection stability of the ink. The surface tension (25 ° C.) of the ink composition is preferably 20 to 60 mN / m.

The ink composition of the present invention is used for image formation of an ink jet recording system, and the ink ejection system is not particularly limited, but among them, one wall shown in FIG. 1 is bent to cause a mechanical pressure difference. It is suitably used for a recording system in which a small image is ejected (flyed) onto a medium by being generated to form a recorded image. In this system, heat is less likely to be transferred to the ink than in the thermal inkjet system, that is, the ink is less likely to be affected by heat, so that an image can be formed without impairing the characteristics of polyester.

According to the present invention, an ink set made of the above ink composition, specifically, an ink set made of an ink composition containing a cyan dye, a magenta dye and a yellow dye as color materials, and further as a color material An ink set is provided that includes an ink composition that includes a black dye. These ink sets are excellent in color development and color balance.

[0035]

EXAMPLES The present invention will be described more specifically based on Examples and Comparative Examples, but the present invention is not limited to these Examples.

An ink composition was prepared according to the formulation shown in Table 1. That is, after adding a dye to water and stirring at room temperature to completely dissolve the dye, a water-dispersed polyester resin (compound),
An organic solvent and other additives were sequentially added, and finally a surfactant was added, and the mixture was stirred at room temperature for 1 hour and filtered with a 2.0 μm filter to obtain an ink composition. In addition, Table 1
Figures in all cases are parts by weight and total amount is 100
Is. In addition, TEGBE is triethylene glycol monobutyl ether, IPA is isopropanol, PES
1 to 4 represent water-dispersed polyester resins 1 to 4.

Table 2 shows the physical properties of PES 1 to 4 used in the examples and other resins used in the comparative examples.

[0038]

[Table 1]

[0039]

[Table 2]

(Experiment 1: High-speed printing) Each of the prepared ink compositions was printed at a printing density of 5 by using a remodeled inkjet printer (AJ2000) manufactured by Sharp Corporation.
%, 7PPM was continuously printed, and the number of printable sheets was examined. The number of printable sheets until the ink tank is filled with the ink composition and becomes empty is about 200 sheets. In this experiment, the ink composition was refilled when the ink tank became empty, and this operation was repeated until printing could not be performed, and the number of sheets that could be printed by that time was defined as the number of printable sheets. "○" when the number of printable sheets exceeds 200, 1
The case of 50 to 200 sheets was evaluated as “Δ”, and the case of less than 150 sheets was evaluated as “x”. Table 3 shows the obtained results.
Shown in.

(Experiment 2: Evaluation of bleeding property) Each of the prepared ink compositions was used to print a specific pattern on a PPC paper (SF4AM3, manufactured by Sharp Corporation) and left for 1 day. Then, the line width of the printed matter was measured, and the relative value when the line width was assumed to be 100 assuming no bleeding was determined. When the relative value is less than 150, it is "○", when it is 150 to 250, it is "△", 250
The case where it exceeded was evaluated as "x". The results obtained are shown in Table 3.

(Experiment 3: Drying speed) Printing was carried out using each of the prepared ink compositions, and the printing was started immediately after printing with the starting point of 15
After a second, a paper of the same quality as that used for printing was pressed against the printing surface, and when transferred, it was evaluated as “x”, and when not transferred, it was evaluated as “◯”. The results obtained are shown in Table 3.

(Experiment 4: Water resistance test) Printing was carried out using each of the prepared ink compositions, and immediately after printing, the starting point was
It was left at room temperature for 24 hours. The sample was exposed to running water for 10 seconds and dried at room temperature overnight. The state of the ink flowing out from the printing portion in the dried sample was evaluated according to the following 5 grades, 3 or more were evaluated as “◯”, and 2 or less were evaluated as “x”. The results obtained are shown in Table 3. Evaluation 1: The color of the printed part flows out and the original color changes. 2: The printed part clearly flows out. 3: The printed part slightly flows out. 4: The printed part does not look good. It is not understood that it is flowing out 5: The printing part is not flowing out

[0044]

[Table 3]

From the results shown in Table 3, the following can be seen. From the comparison between Examples 1 to 4 and Comparative Examples 1 to 4, the ink composition of the present invention containing the specific water-dispersed polyester resin is
It can be seen that stable printing is possible, and the image (print) formed thereby has excellent water resistance and bleeding resistance. From the results of Experiment 2, it can be seen that the bleeding property decreases when the organic solvent is contained in an amount of 50% or more.

[0046]

EFFECTS OF THE INVENTION According to the present invention, it is possible to provide a water-based ink composition for ink jet which is resistant to bleeding, excellent in water resistance, and capable of high-quality printing even in high-speed printing.

[Brief description of drawings]

FIG. 1 is a schematic diagram (inkjet head portion) showing an example of a recording method in which the ink composition of the present invention is used.

[Explanation of symbols]

1 wall

Continued front page    (72) Inventor Seita Suzuki             22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka             Inside the company (72) Inventor Hiroaki Nakaya             22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka             Inside the company (72) Inventor Hiromi Nakatsu             22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka             Inside the company (72) Inventor Masaki Kinomoto             22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka             Inside the company F-term (reference) 2C056 EA13 FC01                 2H086 BA53 BA56 BA59 BA60 BA62                 4J039 AE06 BC07 BC09 BC10 BC14                       BC15 BC49 BE02 BE12 BE22                       CA06 EA15 EA16 EA17 EA19                       EA38 EA42 EA47 GA24

Claims (11)

[Claims] 1. An aqueous dispersion comprising (a) a coloring material selected from dyes, and (b) a weight average molecular weight of 30,000 or less, a hydroxyl value of 13 or less, an acid value of 20 or less, and a particle diameter of 200 nm or less. A water-based inkjet ink composition comprising a polyester resin. 2. The aqueous ink composition for inkjet according to claim 1, further comprising a water-soluble organic solvent having a vapor pressure lower than that of water at an environment temperature in which the ink is used, and the compounding amount thereof is 1 to 50% by weight. 2. The water-based ink composition for ink jet. 3. The water-soluble organic solvent is polyethylene glycol, diethylene glycol, ethyl carbitol, triethylene glycol monobutyl ether, 1,5-pentanediol, glycerin, 2-pyrrolidone and N.
The aqueous ink composition for inkjet according to claim 2, which is at least one selected from methylpyrrolidone. 4. Further comprising a nonionic surfactant,
The aqueous ink composition for inkjet according to any one of claims 1 to 3, wherein the blending amount is not less than the critical micelle concentration. 5. The ink-jet aqueous ink composition according to claim 1, wherein the coloring material is at least one cyan dye selected from Acid Blue 7, Acid Blue 9 and Direct Blue 199. object. 6. The coloring material is at least one magenta dye selected from Acid Red 52, Acid Red 289, Reactive Red 58, Reactive Red 141 and Reactive Red 180.
The water-based ink composition for inkjet according to any one of 4 above. 7. The coloring material is at least one yellow dye selected from Acid Yellow 17, Acid Yellow 23 and Direct Yellow 86.
The water-based ink composition for inkjet according to any one of 4 above. 8. The water-based inkjet ink composition according to claim 1, wherein the coloring material is at least one black dye selected from Food Black 2 and Direct Black 154. 9. The recording system according to claim 1, which is used in a recording system in which a recording image is formed by ejecting ink droplets onto a medium by bending to generate a mechanical pressure difference. 2. The water-based ink composition for ink jet. 10. A cyan dye, a magenta dye and a yellow dye are separately contained as color materials.
An ink set in which the water-based inkjet ink composition according to any one of 1 and 9 is combined. 11. An ink set comprising a combination of the water-based inkjet ink composition according to any one of claims 1 to 9, which contains a cyan dye, a magenta dye, a yellow dye, and a black dye separately as color materials.