Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Patent
1993-03-22
1997-03-04
Michl, Paul R.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
524377, 524379, 523160, 523161, 260DIG38, C08L 2904
Patent
active
056079990
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Technical Field
The present invention relates to a water-based ink containing a pigment as a coloring material and used for an ink jet printer wherein recording is conducted with a liquid ink.
2. Background Art
In the prior art, an ink comprising water, an organic solvent, a wax or other substance and, dissolved therein, a dye as a coloring agent has been mainly used as an ink for ink jet recording. Such an ink has poor light fastness and water resistance derived from properties of the dye. In order to solve this problem, a proposal has been made on an ink wherein a pigment, such as carbon black or aniline black, was used as the coloring agent. For example, an ink containing a water-soluble polymer in addition to the pigment is described in Japanese Patent Publication No. 15542/1989 and Japanese Patent Laid-Open Nos. 63766/1983, 255875/1990 and 276874/1990.
An ink of a water dispersion system can improve printing density, light fastness and water resistance, etc. as compared with an ink of a dye system. The ink for ink jet recording, however, should have properties such that it does not clog a fine ejection nozzle, has excellent rubbing resistance and setting to dry in the print, is free from aggregation or settlement of solid matter, such as a pigment particle, and exhibits no change in the properties of the ink even when stored at a high temperature or a low temperature for a long period of time and can be redispersed by stirring or further addition of a solvent even when the pigment once aggregated.
The above conventional inks have not yet satisfied all the property requirements of an ink jet printer.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide a water-based recording ink of a pigment system which can satisfy various property requirements of an ink jet recording ink.
A water-based recording ink according to the present invention comprises water, a pigment, a water-soluble homopolymer and a copolymer having both a hydrophobic portion and a hydrophilic portion.
The present invention can provide a print having excellent density, light fastness and water resistance. Further, the present invention can provide a water-based recording ink having such various properties necessary for use as an ink jet recording ink that it does not clog a fine ejection nozzle, has excellent rubbing resistance and setting to dry in the print, is free from aggregation or settlement of solid matter, such as a pigment particle, and exhibits no change in the properties of the ink even when stored at a high temperature or a low temperature for a long period of time and can be redispersed by stirring or further addition of a solvent even when the pigment once aggregated.
BRIEF DESCRIPTION OF THE DRAWING
The accompanying FIGURE is a diagram showing the structure of a head in an ink jet printer used in an evaluation test for the ink composition according to the present invention.
DETAILED DESCRIPTION OF THE INVENTION
The term "water-soluble homopolymer" contained in the ink of the present invention is intended to mean a water-soluble or aqueous-solution-soluble homopolymer having a polar group (for example, an ionic group, a hydroxyl group, an amino group, an amide group or an ether group). Particularly preferred examples of the water-soluble homopolymer include a homopolymer having such a structure that the above-described polar group is introduced into a polyethylene chain. Preferred examples of the homopolymer include polyalcohols such as polyvinyl alcohol, polyvinyl pyrrolidone and modification products thereof wherein a hydrophilic group, such as a hydroxyl group, a carboxyl group, an ethylene oxide group or an amine group is further introduced.
Still preferred examples of the water-soluble homopolymer used in the present invention include natural polymers such as glue, gelatin, casein, albumin and gum arabic, alginic acid and its derivatives such as alginic acid, propylene glycol alginate, triethanolamine alginate and ammonium alginate, cellulose d
REFERENCES:
patent: 4597794 (1986-07-01), Ohta et al.
patent: 4791165 (1988-12-01), Bearss
patent: 5004763 (1991-04-01), Imagawa
Derwent Publications Ltd., Database WPI Week 8434, AN 84-209557 London, G.B .
Shimizu Junko
Tsukahara Michinari
Yanase Nobuyuki
Guarriello John J.
Michl Paul R.
Seiko Epson Corporation
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