JP2003003093A - Ink set - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink set that is capable of providing a printing object having excellent storage stability and color development without a possibility of color bleeding, etc. SOLUTION: This ink set is composed of an aqueous black pigment ink composition and at least one kind of aqueous pigment ink composition having other color than black, wherein it is characterized in that the aqueous black pigment ink composition contains pigment, polyethyleneimine, (2-phenoxyethyl methacrylate)-styrene copolymer and water, and the aqueous pigment ink composition having other color than black contains pigment, styrene-acrylic acid copolymer and water.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink set comprising a black aqueous pigment ink composition and at least one non-black aqueous pigment ink composition, and particularly to a printed matter having excellent storage stability and color developability. In addition, the present invention relates to an ink set that is capable of causing color bleeding and the like.

[0002]

2. Description of the Related Art An ink jet recording method is a recording method in which droplets of ink are ejected and adhered to a recording medium such as paper for printing. This recording method is rapidly spreading in various fields because multicolor printing can be easily performed by using an ink set composed of inks of a plurality of colors. As an ink used for ink jet recording, a water-based ink containing water as a main component and a coloring material, an organic solvent, and various other additives is generally used. Color materials include dyes and pigments, which have high saturation,
Dyes are currently the mainstream due to their abundance of varieties and their solubility in water. However, since dyes are generally inferior in weather resistance, the printed matter on which characters and / or images are printed by dye ink has a drawback that image fastness is inferior.
On the other hand, since pigments have excellent weather resistance, demand for them has been increasing in recent years, and development of water-based pigment inks utilizing the characteristics of pigments has been underway.

In general, an aqueous pigment ink is required to have characteristics such as excellent storage stability and printed matter having excellent color development. As a water-based pigment ink satisfying such characteristics, a water-based pigment ink containing polyethyleneimine is known (for example, JP-A-6-329964, JP-A-10-36726 and JP-A-10-26).
No. 60352, etc.).

[0004]

When a conventional ink set composed of a plurality of water-based pigment inks is used for multicolor printing on a recording medium, the colors are mixed at the boundaries of different colors and the boundaries become unclear. There was a problem of causing a phenomenon, so-called color bleed. In addition, in the conventional ink set, even when the ink is ejected in a single color, the phenomenon in which the single color portion spreads to the surroundings (so-called color bleeding) and the pulp fiber that constitutes the paper (recording medium) There is also a problem in that the ink spreads and causes a phenomenon in which whiskers are formed (so-called feathering). These phenomena are particularly noticeable between the black ink portion and the color ink portion (particularly the yellow ink portion), resulting in a significant deterioration in image quality.

Therefore, it is an object of the present invention to provide an ink set which is capable of providing a printed matter which is excellent in storage stability and color developability and which does not cause color bleeding or the like.

[0006]

Means for Solving the Problems As a result of various studies on the aqueous pigment ink containing polyethyleneimine capable of providing a printed matter having excellent storage stability and color development, the present inventors have found that styrene- When polyethyleneimine is added to an aqueous pigment ink containing an acrylic acid copolymer, the aqueous pigment ink aggregates and gels,
As a dispersant (-2-phenoxyethyl methacrylate)
-It was found that the addition of polyethyleneimine to an aqueous pigment ink containing a styrene copolymer does not cause the aqueous pigment ink to gel, and the difference in the dispersant of the aqueous pigment ink containing such a polyethyleneimine. It has been found that color bleeding and the like can be prevented by applying the presence or absence of gelation due to the above to an ink set composed of a black aqueous pigment ink composition and at least one type of non-black aqueous pigment ink composition.

The present invention has been made based on the above findings, and in an ink set comprising a black aqueous pigment ink composition and at least one kind of aqueous pigment ink composition other than black, the black aqueous pigment ink composition But the pigment,
Polyethyleneimine, (2-phenoxyethyl methacrylate) -styrene copolymer and water are contained, and the aqueous pigment ink composition other than black contains a pigment, styrene-acrylic acid copolymer and water. The above object is achieved by providing an ink set.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The ink set of the present invention will be described in detail below. The ink set of the present invention, as described above,
An ink set comprising a black water-based pigment ink composition and at least one water-based pigment ink composition other than black, wherein the black water-based pigment ink composition comprises a pigment, polyethyleneimine, and (2-phenoxyethyl methacrylate). −
An aqueous pigment ink composition containing a styrene copolymer and water and having a color other than black contains a pigment, a styrene-acrylic acid copolymer, and water.

The polyethyleneimine contained in the black aqueous pigment ink composition according to the present invention may be that used in this type of ink, and may be anion-modified or cation-modified. The weight average molecular weight of polyethyleneimine is preferably 500 to 10
000, and more preferably 800 to 2000.

The polyethyleneimine is preferably contained in the black aqueous pigment ink composition of the present invention in an amount of 0.1 to 3
%, More preferably 0.2 to 1% by weight.
When the content is less than 0.1% by weight, the print quality is not improved and the effect of preventing color bleeding, color bleeding, feathering, etc. is poor, and when the content exceeds 3% by weight, the ink viscosity increases and the handleability of the ink is poor. There is a risk that the stability will decrease.
In addition, the above (2-phenoxyethyl methacrylate)-
The styrene copolymer is preferably 0.1 to 20% by weight, more preferably 0.1 to 20% by weight in the black aqueous pigment ink composition according to the present invention, from the viewpoint of the balance between pigment dispersion stability and ink handling property. 1-10% by weight, more preferably 2-1
Contains 0% by weight.

On the other hand, as the styrene-acrylic acid copolymer contained in the aqueous pigment ink composition other than black according to the present invention, styrene-acrylic acid which is usually used as a dispersant in this type of ink. Copolymers are preferably used, but in particular, the weight average molecular weight is preferably 1000 to 100000, more preferably 5000 to 1
It is preferable to use the one of 0000.

The styrene-acrylic acid copolymer is used in the aqueous pigment ink composition other than black according to the present invention, from the viewpoint of the balance between pigment dispersion stability and ink handling property.
Preferably 0.1 to 20% by weight, more preferably 0.5.
10 to 10% by weight, more preferably 2 to 5% by weight.

As the pigment contained in the aqueous pigment ink composition according to the present invention, the same pigments used in this type of ink can be used. Examples thereof include azo lake, insoluble azo pigment and condensed azo pigment. Organic pigments such as chelate azo pigments, phthalocyanine pigments, perylene pigments, perinone pigments, quinacridone pigments, thioindigo pigments, isoindolinone pigments, quinofuraron pigments, dioxazine pigments, anthraquinone pigments, nitro pigments, nitroso pigments, aniline black; titanium white, zinc Examples include inorganic pigments such as white, lead white, carbon black, red iron oxide, vermilion, cadmium red, yellow lead, ultramarine blue, cobalt blue, cobalt purple, and zinc chromate. Further, any pigment not listed in the color index can be used as long as it can be dispersed in the aqueous phase. In addition, "pigment" means water, solvent,
A particulate solid that is insoluble in oil and the like.

The pigment is contained in the aqueous pigment ink composition according to the present invention in an amount of preferably 0.5 to 15% by weight, more preferably 2 to 10% by weight. 0.5% by weight
If it is less than 10% by weight, the printing density is insufficient, and if it exceeds 15% by weight, the viscosity may increase or the nozzle may be clogged when used as an ink for inkjet recording.

The aqueous pigment ink composition according to the present invention includes
From the viewpoint of increasing the wettability to the recording medium and increasing the permeability,
A penetration enhancer can be included. As the penetration enhancer, one having an action of lowering the surface tension of the aqueous solution (aqueous pigment ink composition) is used, and a water-soluble organic solvent and / or
Alternatively, it is preferable to use a surfactant. Examples of the water-soluble organic solvent include lower alcohols such as ethanol and propanol; cellosolves such as ethylene glycol monomethyl ether and ethylene glycol monoethyl ether; carbitols such as diethylene glycol monomethyl ether and diethylene glycol monoethyl ether; ethylene glycol. Examples thereof include glycol ethers such as mono-n-butyl ether, diethylene glycol-n-butyl ether, and triethylene glycol-n-butyl ether, and one or more of these may be used. Examples of the surfactant include fatty acid salts; anionic surfactants such as alkyl sulfate ester salts; nonionic surfactants such as polyoxyethylene alkyl ethers and polyoxyethylene alkylphenyl ethers; Surfynol 61, 82, 1
04, 440, 465, 485 (all are trade names, air
Acetylene glycol-based surfactants such as Products and Chemicals), cationic surfactants, amphoteric surfactants, and the like, and one or more of these may be used. The penetration enhancer is preferably contained in the aqueous pigment ink composition according to the present invention in an amount of 0.5 to 40% by weight, more preferably 2 to 30% by weight.

The aqueous pigment ink composition according to the present invention may contain a humectant from the viewpoint of improving ejection stability. As the humectant, those similar to those in the aqueous pigment ink composition of this type can be used without particular limitation, and for example, glycerin, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, propylene glycol. , Dipropylene glycol, polypropylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol 1,6-hexanediol, 1,2,6-hexanetriol, pentaerythritol and other polyols ,
Lactams such as 2-pyrrolidone, N-methyl-2-pyrrolidone and ε-caprolactam, ureas such as urea, thiourea, ethyleneurea and 1,3-dimethylimidazolidinone, maltitol, sorbitol and gluconolactone. ,
Examples include sugars such as maltose, and one or two of these.
More than one seed is used. The humectant is preferably 0.5 to 40% by weight in the aqueous pigment ink composition according to the present invention,
More preferably, the content is 2 to 30% by weight.

The aqueous pigment ink composition according to the present invention includes
As described above, the pigment and polyethyleneimine and (2-phenoxyethyl methacrylate) -styrene copolymer or styrene-acrylic acid copolymer are contained, and if necessary, a penetration enhancer and a humectant. And water as a balance. As water, it is preferable to use pure water or ultrapure water such as ion-exchanged water, ultrafiltered water, reverse osmosis water, and distilled water. In particular, water obtained by sterilizing these waters by ultraviolet irradiation, addition of hydrogen peroxide, or the like is preferable because molds and bacteria are prevented from being generated for a long period of time.

The aqueous pigment ink composition according to the present invention includes
Further, if necessary, a fixing agent such as water-soluble rosin, an antifungal agent / preservative such as sodium benzoate, an antioxidant / ultraviolet absorber such as alohanates, an ultraviolet absorber, a chelating agent, an oxygen absorber,
An additive such as a pH adjuster can be contained, and one kind or two or more kinds of them can be used. As each of these additives, the same ones as those in the aqueous pigment ink composition of this type can be used without particular limitation.

The aqueous pigment ink composition according to the present invention is prepared by using a conventionally known apparatus such as a ball mill, a sand mill, an attritor, a basket mill or a roll mill.
It can be prepared in the same manner as a conventional pigment ink. At the time of preparation, it is preferable to remove coarse particles using a membrane filter or a mesh filter.

The ink set of the present invention can be suitably used in any method as long as it is a recording method in which an aqueous pigment ink composition is adhered to a recording medium to perform printing. As such a recording method, for example, an ink jet recording method which is a recording method of ejecting droplets of an aqueous pigment ink composition and adhering the droplets to a recording medium to perform printing, and a recording method using a writing instrument such as a pen. , And various other printing methods, and particularly preferably used for an inkjet recording method, particularly an on-demand type inkjet recording method. As the on-demand type inkjet recording method, for example, a piezoelectric element recording method in which recording is performed using a piezoelectric element arranged in a printer head, and heat energy by a heater of a heating resistance element arranged in the printer head is used. A thermal jet recording method for performing recording by the above method can be used, and it can be suitably used for any inkjet recording method.

When the ink set of the present invention is used for multicolor printing on a recording medium, polyethyleneimine and (methacrylic acid-2) are added to a black aqueous pigment ink composition.
Styrene containing a (phenoxyethyl) -styrene copolymer, and an aqueous pigment ink composition other than black causes gelation by the addition of polyethyleneimine-
Since it is an ink of acrylic acid copolymer dispersion system,
At the boundary between the black ink portion and the other color ink portion (color ink portion), the color ink gels, and as a result, color bleeding, color bleeding, and feathering are prevented.

Further, the ink set of the present invention can provide a printed matter excellent in storage stability and color development due to the action of polyethyleneimine contained in the black aqueous pigment ink composition, and in particular, a recording medium. This is effective when size-treated paper is used as. The ink set of the present invention,
The reason why it is particularly effective for size-treated paper is that polyethyleneimine contained in the black aqueous pigment ink composition reacts with the carboxyl groups on the surface of the recording medium to cause gelation of the black aqueous pigment ink composition. It is speculated that a large amount of the pigment remains on the recording medium as a result. Further, the size-treated paper means a recording medium in which a sizing agent is internally added and / or surface-coated, and the recording medium is plain paper (a recording medium in which fibers are exposed on the recording surface). Besides, coated paper is also included.

The present invention can be variously modified without departing from the spirit thereof. The ink set of the present invention may be an ink set composed of a black aqueous pigment ink composition and at least one non-black aqueous pigment ink composition, and the type and number of ink colors are not particularly limited.

[0024]

EXAMPLES The present invention will be described more specifically with reference to Examples of the present invention and Test Examples showing the effects of the present invention.
The present invention is not limited to the embodiments.

Example 1 Aqueous pigment ink compositions of four colors of black, cyan, magenta and yellow were prepared, and an ink set 1 comprising these aqueous pigment ink compositions was obtained. The composition of each water-based pigment ink composition was as follows, and each of them was prepared in the following manner. After mixing the pigment, the dispersant, and water to form a mixture, and dispersing the mixture in a sand mill (manufactured by Yasukawa Seisakusho) with glass beads (diameter 1.7 mm) in an amount 1.5 times (by weight) the mixture, for 2 hours. Then, the glass beads were removed to obtain a pigment dispersion liquid. Then, an ink solvent is prepared by mixing and dissolving components (solvents and additives) other than the pigment and the dispersant in the following composition, and the ink solvent is gradually added to the pigment dispersion while stirring the pigment dispersion. It was dropped and stirred at room temperature for 20 minutes. Then, this was filtered through a 5 μm membrane filter to obtain an aqueous pigment ink composition for inkjet recording.

[0026] <Composition 1 of black aqueous pigment ink composition> Carbon black MA-7 (pigment, manufactured by Mitsubishi Chemical Corporation) 4.0% by weight -(2-Phenoxyethyl methacrylate) -styrene copolymer   (Dispersant, molecular weight 10,000) 2.0% by weight ・ Polyethyleneimine   (Gelling agent, Aldrich Chemical Inc., branched type, Mn = 1800) 0.3% by weight ・ Glycerin 12.0% by weight ・ Surfinol 465 (Nonionic surfactant, manufactured by Air Product and Chemicals, Inc.) 1.0% by weight ・ Triethylene glycol monobutyl ether 5.0% by weight ・ Remaining amount of ion-exchanged water                                                    Total 100.0% by weight

[0027] <Composition of cyan aqueous pigment ink composition> -C. I. Pigment Blue 15: 3 (pigment) 3.0% by weight -Styrene-acrylic acid copolymer-ammonium salt   (Dispersant, molecular weight 10,000) 2.0% by weight ・ Glycerin 5.0% by weight BYK-348 (nonionic surfactant, BYK Chemie) 0.2% by weight ・ Triethylene glycol monobutyl ether 5.0% by weight ・ Remaining amount of ion-exchanged water                                                    Total 100.0% by weight

[0028] <Composition of magenta aqueous pigment ink composition> -C. I. Pigment Red 122 (Pigment) 3.0% by weight -Styrene-acrylic acid copolymer-ammonium salt   (Dispersant, molecular weight 10,000) 2.0% by weight ・ Glycerin 5.0% by weight BYK-348 (nonionic surfactant, BYK Chemie) 0.2% by weight ・ Triethylene glycol monobutyl ether 5.0% by weight ・ Remaining amount of ion-exchanged water                                                    Total 100.0% by weight

[0029]   <Composition of yellow aqueous pigment ink composition> -C. I. Pigment Yellow 74 (Pigment) 3.5% by weight -Styrene-acrylic acid copolymer-ammonium salt   (Dispersant, molecular weight 10,000) 2.0% by weight ・ Glycerin 8.0% by weight BYK-348 (nonionic surfactant, BYK Chemie) 0.5% by weight ・ Triethylene glycol monobutyl ether 5.0% by weight ・ Remaining amount of ion-exchanged water                                                    Total 100.0% by weight

Example 2 An ink was prepared in the same manner as in Example 1 except that a black pigment ink composition consisting of the following <Composition 2 of black pigment ink composition> was used in place of the black pigment ink composition. Got set 2. <Composition 2 of Black Pigment Ink Composition> Carbon black MA-7 (pigment, manufactured by Mitsubishi Chemical Corporation) 4.0 wt% (2-phenoxyethyl methacrylate) -styrene copolymer (dispersant, molecular weight 10,000) 2.0% by weight-Polyethyleneimine (gelling agent, manufactured by Aldrich Chemical Inc., branched type, Mn = 600) 0.3% by weight-Glycerin 12.0% by weight-Surfinol 465 (nonionic type) Surfactant, manufactured by Air Product and Chemicals, Inc.) 1.0 wt% ・ Triethylene glycol monobutyl ether 5.0 wt% ・ Ion-exchanged water balance 100.0 wt%

[Comparative Example 1] An ink was prepared in the same manner as in Example 1 except that a black pigment ink composition having the following <Composition 3 of black pigment ink composition> was used in place of the black pigment ink composition. Got set 3. <Composition 3 of black pigment ink composition> Carbon black MA-7 (pigment, manufactured by Mitsubishi Chemical Corporation) 4.0% by weight Styrene-acrylic acid copolymer-ammonium salt (dispersant, molecular weight 10,000) ) 2.0% by weight-Glycerin 12.0% by weight-Safynol 465 (nonionic surfactant, manufactured by Air Product and Chemicals, Inc.) 1.0% by weight-Triethylene glycol monobutyl ether 5.0% by weight % ・ Deionized water balance 100.0% by weight

[Comparative Example 2] An ink was prepared in the same manner as in Example 1 except that a black pigment ink composition having the following <Composition 4 of black pigment ink composition> was used in place of the black pigment ink composition. Got set 4. <Composition 4 of Black Pigment Ink Composition> Carbon Black MA-7 (Pigment, manufactured by Mitsubishi Chemical Corporation) 4.0 wt% • (2-phenoxyethyl methacrylate) -styrene copolymer (dispersant, Molecular weight 10,000) 2.0% by weight-Glycerin 12.0% by weight-Safynol 465 (nonionic surfactant, manufactured by Air Product and Chemicals, Inc.) 1.0% by weight-Triethylene glycol monobutyl ether 5.0% by weight ・ Residual amount of ion-exchanged water 100.0% by weight

Comparative Example 3 In place of the black pigment ink composition, the following <composition of black dye ink composition>
An ink set 5 was obtained in the same manner as in Example 1 except that the black dye ink composition consisting of This black dye ink composition was prepared by adding a dye to an ink solvent, stirring and dissolving at room temperature for 20 minutes, and then filtering with a 5 μm membrane filter. <Composition of black dye ink composition> -Project Fast Black 2 (dye, manufactured by AVECIA) 3.5% by weight-Glycerin 10.0% by weight-Surfinol 465 (nonionic surfactant, Air Product and Chemicals, Inc.) 1.0 wt% -Triethylene glycol monobutyl ether 7.0 wt% -Deionized water balance 100.0 wt%

[Test Example] Examples 1 and 2 and Comparative Examples 1 to 3
An ink jet printer (trade name "EM-900C", manufactured by Seiko Epson Corp.) was used to print on the recording medium with each of the ink sets described in 1. above, and prints were obtained. Then, these printed materials were evaluated for color bleeding immediately after printing, color bleeding after printing, and feathering after printing by the following tests. The results are shown in [Table 1] below. As the recording medium, "Xerox
P "(trade name, manufactured by Xerox Co., Ltd.)," Xerox40
24 "(trade name, manufactured by Xerox Co., Ltd.) and" quality plain paper "(manufactured by Seiko Epson Co., Ltd., model number KA4250N)
Three types of plain paper of P) were used. The print mode is
Recommended setting (clean) mode.

(Color Bleed Evaluation Test Immediately After Printing) For each printed matter immediately after printing, the areas in which yellow and black are overlapped and printed (areas in which deterioration in image quality is most easily discerned) are visually observed, and black The degree of color bleeding was evaluated according to the following evaluation criteria. <Evaluation Criteria> A: A good image without color blur was obtained. B: Slight color bleeding occurred. C: The occurrence of color blur was clearly recognized. D: Bleeding occurred to such an extent that the color boundary was not clear.

(Color bleed evaluation test after printing) For each printed matter after being naturally dried, the areas where yellow and black are overlapped and printed (areas where image quality deterioration is most recognizable) are visually observed. Then, the degree of uneven color mixing at those color boundaries was evaluated according to the following evaluation criteria. <Evaluation Criteria> A: A good image having no color mixture was obtained. B: Slight color mixing occurred. C: Occurrence of color mixing was recognized. D: Color mixing occurred to such an extent that the color boundary was not clear.

(Feathering Evaluation Test After Printing) With respect to each of the above-mentioned printed matters after natural drying, the areas where yellow and black are overlapped and printed (areas where image quality deterioration is most recognizable) are visually observed. Then, the presence or absence of black beard-like exudation was evaluated according to the following evaluation criteria. <Evaluation Criteria> A: A good image having no beard-like bleeding was obtained. B: Slight beard-like bleeding occurred. C: Mustache-like exudation was observed. −: Evaluation was not possible due to severe blurring and color bleeding.

[0038]

[Table 1]

As is clear from the results shown in Table 1, each of the ink sets of Examples 1 and 2 is free from color bleeding, color mixing, and whisker-like bleeding, and can provide a high-quality printed matter. I see that it is possible. On the other hand, each of the ink sets of Comparative Examples 1 to 3 was not able to provide a high quality printed matter because the color bleeding of the printed matter was severe.

[0040]

According to the ink set of the present invention, it is possible to provide a high-quality printed matter which is excellent in color developability and has no color bleeding or the like. Further, the ink set of the present invention has excellent storage stability and can be stored for a long period of time.

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2C056 FC01                 2H086 BA21 BA55 BA59 BA62                 4J039 AD03 AD09 AD10 AE09 BE01                       CA03 CA06 EA19 EA21 EA44                       EA47 GA24

Claims (8)

[Claims] 1. An ink set comprising a black water-based pigment ink composition and at least one water-based pigment ink composition other than black, wherein the black water-based pigment ink composition comprises a pigment, polyethyleneimine, and (methacrylic acid- 2-phenoxyethyl)-
An ink set containing a styrene copolymer and water, wherein the aqueous pigment ink composition other than black contains a pigment, a styrene-acrylic acid copolymer and water. 2. The black aqueous pigment ink composition comprises 0.1 to 3% by weight of the polyethyleneimine and 0.1 to 20% by weight of the (2-phenoxyethyl methacrylate) -styrene copolymer. The ink set according to claim 1, which contains. 3. The ink set according to claim 1, wherein the polyethyleneimine has a weight average molecular weight of 500 to 10,000. 4. The aqueous pigment ink composition other than black contains 0.1 to 20 of the styrene-acrylic acid copolymer.
The ink set according to any one of claims 1 to 3, wherein the ink set contains wt%. 5. The ink set according to claim 1, which is used in an inkjet recording method. 6. A recording method for forming characters and / or images on a recording medium using the ink set according to claim 1. 7. The recording method according to claim 6, wherein the recording medium is size-treated paper. 8. A recorded matter recorded by the recording method according to claim 6.