Ink compositions for inkjet recording

Details Ink compositions for inkjet recording Ink compositions for inkjet recording

2002-04-11

2004-12-07

Klemanski, Helene (Department: 1755)

Compositions: coating or plastic

Coating or plastic compositions

Marking

C106S031430, C106S031460, C106S031480, C106S031490, C347S100000

Reexamination Certificate

active

06827771

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to an ink composition for inkjet recording (which will hereinafter be called “inkjet recording ink composition”) capable of providing high-quality recorded images, excellent in discharge stability and also excellent in shelf life of the images thus formed; and also to an inkjet recording method.
BACKGROUND OF THE INVENTION
With recent widespread use of computers, inkjet printers have come to be used not only at offices but also at home for printing images on paper, film or cloth. As an ink for inkjet recording, oil-based inks, aqueous inks and solid inks are known. Of these, aqueous inks are most popularly employed in consideration of manufacturing ease, handling ease, odor and safety.
Although many aqueous inks have merits in high transparency and high color density because of containing a water-soluble dye which is dissolved in a molecular state, they are accompanied with the drawbacks that owing to inferior water resistance, bleeding occurs when printed on so-called plain paper, leading to a deterioration in the print quality and moreover, they are markedly inferior in the shelf life of images, more specifically, light fastness and resistance to oxidizing gases (such as SO
x
, NO
x
and ozone).
A variety of aqueous inks have been proposed using a pigment or a disperse dye with a view toward overcoming the above-described drawbacks. These proposals are described, for example, in Japanese Patents Laid-Open Nos. 157468/1981, 18468/1992, 110126/1998 and 195355/1998. These aqueous inks have improved water resistance, but not completely improved. Particularly, pigment inks involve such problems as that they are inferior in color development to dye inks and insufficient storage stability of a dispersion tends to cause clogging at the discharge outlet. Disperse dyes are, on the other hand, comparable to water soluble dyes in transparency and color density, but the shelf life of images cannot be heightened to the level of water soluble dyes.
A method of encapsulating a dye in urethane polymer latex particles is proposed in Japanese Patent Laid-Open No. 45272/1983, but this method involves such a drawback as difficulty in obtaining colored particles excellent in dispersion stability when the dye encapsulated in the particles has a desired concentration. In Japanese Patent Laid-Open No. 279873/1998, disclosed is a method of preparing fine colored polymer particles by dissolving an acrylic polymer and an oil soluble dye in an organic solvent and after dispersing, removing the organic solvent. This method is however accompanied with the problem in the quality of recorded images, particularly, quality of images recorded on a photographic paper medium and stability of the quality upon continuous recording.
In Japanese Patent Publication No. 76977/1993, disclosed is an ink composition obtained by dissolving and dispersing an oil soluble dye in an organic solvent. The organic solvent specified therein has, in general, only insufficient compatibility with an oil soluble dye so that recording density is low and it has been revealed that in some cases, precipitation of the dye occurs during storage, causing clogging of a nozzle.
In Japanese Patent Laid-Open No. 16171/1990, proposed is use of a dye excellent in color development and shelf life of images in order to prepare an ink composition satisfactory in all of water resistance, color development and shelf life of images. Color cannot be reproduced well because of insufficient color tone and in addition, storage stability of the image thus formed is insufficient.
In Japanese Patent Laid-Open No. 170674/1989, disclosed is an inkjet recording solution containing an ultraviolet absorber and/or antioxidant in order to improve the shelf life of images, but this solution is not sufficient in light fastness.
SUMMARY OF THE INVENTION
Under such situations, there is accordingly a demand for development, as a method capable of attaining all of water resistance, color development and shelf life of images, a technique permitting formation of an image sufficient in image quality, water resistance and shelf life of images by using an ink containing both a dye excellent in color development and shelf life of images and an antifading agent capable of sufficiently improving the image fastness of the dye.
An object of the invention is to provide an aqueous ink, which is advantageous from the viewpoints of handling ease, odor and safety, having high discharge stability and good color development and capable of forming an image excellent in color hue, shelf life, stability and water resistance and to overcome the drawbacks in the image quality such as bleeding of thin lines. A further object of the present invention is to provide an inkjet recording ink composition having high discharge stability even after storage over time under severe conditions and free from defects in color hue, shelf life, stability, water resistance and image quality.
The above-described objects are attained by the following compositions or method:
(1) An inkjet recording ink composition obtained by dissolving or dispersing, in an aqueous medium, an azo dye having an aromatic nitrogen-containing 6-membered heterocycle as a coupling component, wherein the composition contains a compound represented by the following formula (I):
wherein, R
101
and R
102
each independently represents a hydrogen atom, an aliphatic group, an aromatic group, a heterocyclic group, an acyl group, an aliphatic oxycarbonyl group, an aromatic oxycarbonyl group, an aliphatic sulfonyl group, an aromatic sulfonyl group, a substituted or unsubstituted carbamoyl group, or a substituted or unsubstituted thiocarbamoyl group;
R
103
represents an aliphatic group, an aromatic group, a heterocyclic group, an aliphatic oxy group, an aromatic oxy group, an aliphatic thio group, an aromatic thio group, an acyloxy group, an aliphatic oxycarbonyloxy group, an aromatic oxycarbonyloxy group, a substituted or unsubstituted amino group or a hydroxy group, or
any of a pair R
101
and R
102
, a pair R
102
and R
103
, and a pair R
103
and R
101
may be coupled to form a 5- to 7-membered ring with the proviso that the ring formed is not a 2,2,6,6-tetraalkylpiperidine skeleton.
(2) An inkjet recording ink composition as described in (1), wherein the azo dye is represented by the following formula (A-1):
wherein,
A represents a 5-membered heterocyclic group,
B
1
and B
2
represent —CR
1
═ and —CR
2
═, respectively, or either one represents a nitrogen atom and the other one represents —CR
1
═ or —CR
2
═,
G, R
1
, and R
2
each independently represents a hydrogen atom, a halogen atom, an aliphatic group, an aromatic group, a heterocyclic group, a cyano group, a carboxyl group, a carbamoyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a heterocyclic oxycarbonyl group, an acyl group, a hydroxy group, an alkoxy group, an aryloxy group, a heterocyclic oxy group, a silyloxy group, an acyloxy group, a carbamoyloxy group, an alkoxycarbonyloxy group, an aryloxycarbonyloxy group, an amino group substituted with an alkyl, aryl or heterocyclic group, an acylamino group, an ureido group, a sulfamoylamino group, an alkoxycarbonylamino group, an aryloxycarbonylamino group, an alkyl- or arylsulfonylamino group, a heterocyclic sulfonylamino group, a nitro group, an alkyl-, aryl- or heterocyclo-thio group, an alkyl- or aryl-sulfonyl group, a heterocyclic sulfonyl group, an alkyl- or aryl-sulfinyl group, a heterocyclic sulfinyl group, a sulfamoyl group or a sulfo group, which may have a substituent further,
R
5
and R
6
each independently represents a hydrogen atom, an aliphatic group, an aromatic group, a heterocyclic group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a carbamoyl group, an alkyl- or aryl-sulfonyl group or a sulfamoyl group, which may have a substituent further, or a pair R
1
and R
5
, or a pair R
5
and R
6
may be coupled to form a 5- or 6-membered ring.
(3) An inkjet recording ink composition as described in (1) or (2), wher

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