JPH08176488A - Water-base ink composition - Google Patents

Abstract

PURPOSE: To improve the water resistance, light fastness, and dispersion stability by incorporating at least a pigment, an aq. medium, and a dispersant of a copolymer of an N-vinylpyrrolidone (or a deriv. thereof) with an alkene compd. CONSTITUTION: 1 to 10wt.%, based on the ink compsn, pigment is mixed with 10 to 120 pts.wt., based on 100 pts.wt. pigment, dispersant of a high-mol. wt. copolymer compd. of N-vinylpyrrolidone (or a deriv. thereof) with an alkene compd. and 0 to 100 pts.wt., based on 100 pts.wt. water, hydrophilic solvent as an aq. solvent, and the mixture is stirred, dispersed, and centrifuged to remove coarse particles to prepare a water-base ink.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-based ink composition, and more particularly to a water-based ink used for ink jet printers, writing instruments, stamps, ribbons and the like.

[0002]

2. Description of the Related Art As a coloring component of water-based inks generally used in printers and writing instruments, from the viewpoint of light resistance and water resistance, they are used as fine particles more insoluble than dyes used by being dissolved in an aqueous solvent. It is known to be advantageous to use pigments which

When such a pigment having excellent light resistance and water resistance is used as a colorant for a water-based ink, if pigment particles are not finely dispersed and stabilized, dispersion of the pigment or aggregation will occur. When it is used as an ink, it appears as a lack of ink suitability such as a decrease in coloring power, clogging of pores, deterioration of storage stability due to caking or thickening.

The dispersant added for stabilizing the dispersion causes a change in surface tension, an increase in viscosity and the like, which causes deterioration of image quality due to bleeding and deterioration of suitability for use due to thickening. .

Particularly in jet printer applications, the resolubility of the dispersant is important, and if this is not the case, the dispersant in the ink will re-dissolve while solidified at the nozzles when the printing is stopped halfway and restarted. It has been pointed out that it may cause clogging without causing a discharge abnormality.

When a pigment is used, the finer the particle size, the stronger the agglomeration force between the pigments. Therefore, the pigment dispersion stabilizing performance of the dispersant itself is maintained very finely by dispersing the pigment for a long period of time. Such high-performance products are required.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional drawbacks, and in the case of using a pigment having excellent light resistance and water resistance as compared with a dye as a colorant. It is an object of the present invention to provide an excellent water-based ink by using a dispersant capable of maintaining long-term dispersion stability without deteriorating various properties of the ink.

[0008]

The aqueous ink composition of the present invention comprises at least a polymer compound obtained by copolymerizing N-vinylpyrrolidone or its derivative and an alkene compound, a pigment, and an aqueous medium. Is.

The N-vinylpyrrolidone derivative is N
-Vinylpyrrolidone, N-vinyl-5-methylpyrrolidone, N-vinyl-5-ethylpyrrolidone, N-vinyl-
5,5-dimethylpyrrolidone, N-vinyl-5,5-diethylpyrrolidone and N-vinyl-5-methyl-5-ethylpyrrolidone are particularly preferred, and the alkene compound is preferably one having 2 to 6 carbon atoms, Particularly, 1-butene and 1-pentene are preferable.

Such a high molecular compound is not particularly limited by its molecular weight, but it is 1000 to 100.
A water-based ink having a molecular weight in the range of 000 is preferable in view of properties such as viscosity and the quality of recorded images.

The polymer compound used in the present invention is N
It has hydrophilicity due to the side chain derived from vinylpyrrolidone and has solubility in an aqueous liquid medium, and has hydrophobicity due to the main chain and the side chain derived from the alkene compound to be adsorbed on the hydrophobic portion of the pigment surface. Due to this, the polymer compound functions as a dispersant.

The pigments used include carbon black, phthalocyanine-based, slene-based, azo-based, quinacridone-based, dioxazine-based, anthraquinone-based, indigo-based, thioindigo-based, azomethine-based, perylene, perinone-based and isoindolinone-based. , Titanium oxide, and other metal oxides.

As the solvent used in the aqueous medium, water or a mixture of water and a hydrophilic organic solvent can be used. Ethanol as the hydrophilic organic solvent,
Normal propanol, isopropanol, normal butanol, secondary butanol, alcohols such as cyclohexanol, acetone, ketones such as methyl ethyl ketone, ethyl acetate, ethyl lactate, esters such as ethylene carbonate, monoethanolamine, diethanolamine, triethanolamine, Alkanolamines such as N, N-dimethylethanolamine and aminoethylethanolamine, amides such as formamide, N-dimethylformamide, N-hydroxymethylformamide, dimethylacetamide, ethers such as dioxane, ethylene glycol, diethylene glycol,
Polypropylene alcohols such as tripropylene glycol and glycerin, ethylene glycol dimethyl ether, ethylene glycol monomethyl ether, triethylene glycol monomethyl ether, ethylene glycol monobutyl ether, triethylene glycol monoethyl ether, triethylene glycol monobutyl ether, tripropylene glycol monomethyl ether And the like, and nitrogen-containing cyclic compounds such as 2-pyrrolidone, N-vinylpyrrolidone, β-hydroxyethylpyrrolidone and N-methylpyrrolidone.

The above-mentioned polymer compound, pigment and aqueous medium are
It is selected and used so as to satisfy desired properties such as mutual affinity, pigment dispersion stability and viscosity.

The proportion of the pigment used in the water-based ink composition of the present invention may be any concentration as long as it gives a sufficient coloring density to the recording medium, but generally from 1 to 1 in the ink composition. A proportion of 10% by weight is preferable.

The amount of the polymer compound used in the water-based ink composition varies depending on the type and brand of the pigment and cannot be unconditionally specified depending on the effect on the viscosity of the water-based ink composition, but is based on 100 parts by weight of the pigment. It is preferably used in a proportion of approximately 10 to 120 parts by weight.

Water and a hydrophilic solvent are used as the aqueous medium, and the hydrophilic solvent is preferably used in a proportion of 0 to 100 parts by weight with respect to 100 parts by weight of water. Further, in the present invention, other known additives can be added as necessary.

The water-based ink composition of the present invention comprises the above-mentioned constituents and blends, and various production methods can be adopted. For example, the above-mentioned various components are blended, and the pigment is mixed and abraded by a conventionally known disperser such as a homomixer, a ball mill, a sand grinder, a speed line mill, and a roll mill, and then the physical properties such as concentration and particle size are adjusted. Ink can be obtained by removing coarse particles by filtration or centrifugation.

The present invention will be described below with reference to examples. In the text, parts are based on weight unless otherwise specified.

(Example 1) Carbon black 10.0 parts (Printech 75 Degussa) N-vinylpyrrolidone, 1-butene copolymer 10.0 parts (molecular weight about 8000) water 30.0 parts The above components were mixed. Then, the dispersion treatment was performed with a paint shaker to obtain a carbon black dispersion liquid. Glycerin (25.0 parts), 2-pyrrolidone (25.0 parts), water (150.0 parts) were added to this carbon black dispersion, and the mixture was stirred after centrifuging to remove coarse particles, the pigment concentration was 4.0%, and the viscosity was 6.7 cp ( 25 ° C)
To obtain an ink for an inkjet printer.

(Example 2) Phthalocyanine green 10.0 parts (Vinamon green 6Y-FW ICI) N-vinylpyrrolidone, 1-butene copolymer 6.0 parts (molecular weight about 8000) water 34.0 parts The components were mixed and dispersed with a paint shaker to obtain a phthalocyanine green dispersion liquid. Sodium lactate 20.0 parts 2-pyrrolidone 30.0 parts Water 150.0 parts were added to this phthalocyanine green dispersion and mixed and stirred, and then the mixture was centrifuged to remove coarse particles, and the pigment concentration was 4.0% and the viscosity was 5.5 cp. (25 ° C)
To obtain an ink for an inkjet printer.

Example 3 Quinacridone Red 10.0 parts (Fastgen Super Magenta RE Dainippon Ink and Chemicals) N-vinyl-5-ethylpyrrolidone 8.0 parts 1-butene copolymer (molecular weight about 8000) water 32.0 parts The above components were mixed and dispersed with a paint shaker to obtain a quinacridone red dispersion liquid. Diethylene glycol 10.0 parts Glycerin 20.0 parts Lyethylene glycol monobutyl ether 20.0 parts Water 150.0 parts are added to this quinacridone red dispersion liquid, mixed and stirred, and then centrifuged to remove coarse particles, and the pigment concentration is 4.0%. , Viscosity 7.5cp (25 ℃)
To obtain an ink for an inkjet printer.

(Example 4) Isoindolinone yellow 10.0 parts (Irgazin yellow 2RLT manufactured by Ciba) N-vinylpyrrolidone, 1-pentene copolymer 5.0 parts (molecular weight about 10,000) Water 35.0 parts The above components were mixed and dispersed with a paint shaker to obtain an isoindolinone yellow dispersion liquid. 2-Pyrrolidone (35.0 parts) Tetrapropylene glycol monomethyl ether (15.0 parts) Water (150.0 parts) was added to this isoindolinone yellow dispersion and mixed and stirred, and then centrifuged to remove coarse particles and a pigment concentration of 4.0%. , Viscosity 5.8cp (25 ℃)
To obtain an ink for an inkjet printer.

Comparative Example 1 A black ink for ink jet printer was obtained in the same manner as in Example 1 except that polyvinyl alcohol (molecular weight: about 20,000) was blended in place of the copolymer of Example 1.

Comparative Example 2 A green ink for inkjet printer was obtained in the same manner as in Example 2 except that polyvinyl alcohol (molecular weight: about 20,000) was blended in place of the copolymer of Example 2.

Comparative Example 3 A red ink for inkjet printer was obtained in the same manner as in Example 3 except that polyvinyl alcohol (molecular weight: about 20,000) was blended in place of the copolymer of Example 3.

Comparative Example 4 A yellow ink for inkjet printer was obtained in the same manner as in Example 4 except that polyvinyl alcohol (molecular weight: about 20,000) was blended in place of the copolymer of Example 4.

(Example 5) Each ink of Examples 1 to 4 and Comparative Examples 1 to 4 was filled in an ink cartridge (manufactured by Hewlett-Packard Co., nozzle diameter 50 µm), and it was confirmed that the ink was ejected. Then, it was allowed to stand at room temperature for a predetermined time, and it was examined whether the ink was normally ejected. Furthermore, when the nozzle was solidified by drying the ink, the nozzle portion was immersed in distilled water for 15 minutes, the water in the nozzle was wiped off, and it was checked again whether or not the ink could be discharged.

[0029]

(Example 6) Phthalocyanine blue 10.0 parts (Lionol blue FG-7330 manufactured by Toyo Ink) N-vinyl-5-methylpyrrolidone 8.0 parts 1-butene copolymer (molecular weight 7000) diethylene glycol 25. 0 parts Urea 7.0 parts Water 49.8 parts Proxel GXL (preservative, made by ICI) 0.2 parts After mixing with the above mixture and performing dispersion treatment in a ball mill, coarse particles were removed by centrifugation. To obtain a blue felt-tip pen ink.

(Example 7) Insoluble Azo Red 10.0 parts (Fuji Fast Red 1010 manufactured by Fuji dye) N-vinylpyrrolidone, 1-butene copolymer 6.0 parts (molecular weight 8000) 2-pyrrolidone 25.0 parts Diethylene glycol 9.0 parts Water 49.8 parts Proxel GXL (preservative, manufactured by ICI) 0.2 parts After mixing with the above mixture and dispersing in a ball mill, coarse particles are removed by centrifugation to remove red An ink for felt-tip pen was obtained.

Example 8 Phthalocyanine Green 10.0 parts (Fastgen Green S manufactured by Dainippon Ink) N-vinyl-5,5-dimethylpyrrolidone 5.0 parts 1-butene copolymer (molecular weight 12000) diethylene glycol 23 0.0 parts Glycerin 5.0 parts Urea 7.0 parts Water 49.8 parts Proxel GXL (preservative, manufactured by ICI) 0.2 parts Mixing with the above composition and dispersing in a ball mill, followed by centrifugation. Then, coarse particles were removed to obtain a green felt-tip ink.

Comparative Example 5 A blue felt-tip pen ink was obtained in the same manner as in Example 6 except that styrene-maleic acid (molecular weight: about 10,000) was blended in place of the copolymer of Example 6.

Comparative Example 6 A red felt-tip pen ink was obtained in the same manner as in Example 7 except that styrene-maleic acid (molecular weight: about 10,000) was blended in place of the copolymer of Example 7.

Comparative Example 7 A green felt-tip pen ink was obtained in the same manner as in Example 8 except that styrene-maleic acid (molecular weight: about 10,000) was blended in place of the copolymer of Example 8.

(Example 9) Examples 6 to 8 and Comparative Example 5
The ink for writing instruments of ~ 7 is filled in a plastic felt-tip pen having a polyester occlusion body and a polyacetal extrusion molding nib (0.58 mmФ), and a writing test immediately after filling, a constant temperature bath test at 50 ° C, and a cap-off test are performed. As a result, the following results were obtained.

[0037]

[0038]

[0039]

(Example 10) Carbon black 8.0 parts (manufactured by Monarch 880 Cabot) N-vinylpyrrolidone, 1-pentene copolymer 8.0 parts (molecular weight about 10,000) ethylene glycol 26.0 parts polyoxyethylene Nonylphenol ether 0.1 part Water 57.7 parts Proxel GXL (preservative, manufactured by ICI) 0.2 parts After mixing with the above mixture and performing dispersion treatment in a ball mill, coarse particles were removed by centrifugation. A black ballpoint pen ink was obtained.

(Example 11) Dioxazine violet 10.0 parts (Chromophtal violet B manufactured by Ciba) N-vinylpyrrolidone, 1-butene copolymer 5.0 parts (molecular weight about 8000) diethylene glycol 20.0 parts 2- Pyrrolidone 5. ． Part Water 59.8 parts Proxel GXL (preservative, made by ICI) 0.2 parts After mixing with the above composition and performing dispersion treatment in a ball mill, coarse particles are removed by centrifugation to obtain a purple ballpoint pen ink. Got

(Example 12) Insoluble azolede 15.0 parts (Fuji Fast Red 7R3300 manufactured by Fuji Dye) N-vinyl-5-ethylpyrrolidone 20.0 parts 1-butene copolymer (molecular weight about 8000) ethylene glycol 20. 0 parts Propylene glycol 5.0 parts Water 39.8 parts Proxel GXL (preservative, made by ICI) 0.2 parts After mixing with the above mixture and performing dispersion treatment in a ball mill, coarse particles are removed by centrifugation. Thus, a red ballpoint pen ink was obtained.

Comparative Example 8 A black ink for a ballpoint pen was obtained in the same manner as in Example 10 except that polyvinylpyrrolidone (molecular weight: about 30,000) was blended in place of the copolymer of Example 10.

Comparative Example 9 A purple ballpoint pen ink was obtained in the same manner as in Example 11 except that polyvinylpyrrolidone (molecular weight: about 30,000) was blended in place of the copolymer of Example 11.

Comparative Example 10 A purple ballpoint pen ink was obtained in the same manner as in Example 12 except that polyvinylpyrrolidone (molecular weight: about 30,000) was blended in place of the copolymer of Example 12.

Example 13 The ballpoint pen inks obtained in Examples 10 to 12 and Comparative Examples 8 to 10 were filled in a ballpoint pen having a ball diameter of 0.4 mmΦ, and the writing performance and the stability with time were tested. I got good results.

[0047]

The present invention can take various changes and modifications to the method and product. The various embodiments described above are for the purpose of further clarifying the content of the present invention and not for limiting the present invention.

As described above, according to the present invention, water resistance,
An aqueous ink composition having excellent light resistance and dispersion stability can be obtained. By using the water-based ink composition, it is possible to easily obtain an ink having excellent stability, which is used for writing instruments, stamps, inkjet printers, ribbons and the like.

Claims (1)

[Claims] 1. An aqueous ink composition comprising at least a pigment, a dispersant, and an aqueous medium, wherein the dispersant is a polymer compound obtained by copolymerizing N-vinylpyrrolidone or a derivative thereof and an alkene compound. Stuff.