Compositions: coating or plastic – Coating or plastic compositions – Marking
Reexamination Certificate
2000-04-07
2002-09-24
Klemanski, Helene (Department: 1755)
Compositions: coating or plastic
Coating or plastic compositions
Marking
C106S031470, C106S031490, C106S031520
Reexamination Certificate
active
06454844
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to dye-based color ink sets having excellent color reproduction and lightfastness.
BACKGROUND ART
Images produced by ink compositions, when exposed to indoor or outdoor light beams, the open air for a long period of time, are frequently deteriorated due to an influence of ultraviolet and visible light, various gas in the air. In particular, in the case of color images produced by a plurality of ink compositions, the presence of even one color ink composition having poor lightfastness causes a change in hue of images, resulting in extremely deteriorated quality of color images. This has led to a demand for ink compositions capable of yielding highly weathering-resistant images which, even when stored for a long period of time, are less likely to be deteriorated.
Further, in recent years, attention has been drawn to ink jet recording. The ink jet recording is a printing method wherein droplets of an ink composition are ejected and deposited onto recording media, such as paper, to conduct printing. This method has a feature that images having high resolution and high quality can be printed at a high speed by means of relatively inexpensive apparatuses. Ink jet recording apparatuses utilizing this method are commercially widely accepted by virtue of good print quality, low cost, relatively quiet operation, graphics-forming capability. Among others, thermal (bubble jet) and piezoelectric drop-on-demand printers have been very successful on the market, and have been widely used as printers for personal computers for office and domestic applications.
In recent years, a method has become used wherein a plurality of color ink compositions are provided and used in the formation of color images by ink jet recording. In general, color images are formed using three colors of a yellow ink composition, a magenta ink composition, and a cyan ink composition, and optionally four colors of the above three color compositions plus a black ink composition. In some cases, six colors of the above four colors plus a light cyan ink composition and a light magenta ink composition are used in the formation of color images. What is required, of ink compositions for the formation of such color images is that they as such can exhibit good color development and, in addition, when used in combination with a plurality of ink compositions, can develop good intermediate colors.
Further, ink composition constituting ink sets used in this ink jet recording are required to have properties such that they have suitable property values, such as viscosity and surface tension values, have high optical density, can yield sharp color tone and images, can yield images having excellent fastness properties, such as excellent waterfastness and lightfastness, have excellent storage stability, and are less likely to cause nozzle clogging, are free from a problem associated with an odor, and are safe, for example, are free from the danger of fire. In order to satisfy a large part of these property requirements, water-base inks prepared by dissolving water-soluble dyes in water or in a mixed solution of water and a water-soluble organic solvent have been used. At that time, ink compositions having various hues are prepared from dyes having various hues.
Various image properties, such as color tone, lightfastness, and waterfastness, are greatly influenced by the properties of colorants in the ink compositions, and various dyes have hitherto been studied in the art, printing and photograph.
SUMMARY OF THE INVENTION
The present inventors have now found that ink sets comprising a combination of specific dye-based color ink compositions can realize images having excellent color reproduction and, at the same time, having excellent lightfastness. The present invention has been made based on such finding.
Accordingly, it is an object of the present invention to provide an ink set which can realize images having excellent color reproduction.
Thus, according to one aspect of the present invention, there is provided an ink set comprising: a yellow ink composition; two magenta ink compositions different from each other in color density, a magenta ink composition with higher color density and a magenta ink composition with lower color density; and two cyan ink compositions different from each other in color density, a cyan ink composition with higher color density and a cyan ink composition with lower color density,
said yellow ink composition containing as a colorant a compound represented by formula (I) or (II):
wherein
R
1
, R
1
′, R
2
, and R
2
′ each independently represent CH
3
or OCH
3
; and
A and A′ each independently represent a group having a structure selected from the group consisting of
wherein
M represents a hydrogen atom, lithium, sodium, potassium, ammonium, or an organic amine; and
n is an integer of 1 or 2,
said magenta ink composition with higher color density containing as a colorant a compound represented by formula (III):
wherein
B and B′ each independently represent a hydrogen atom or a group represented by formula
wherein
R
2
represents OH, COOM, or NHR
5
wherein R
5
represents an SO
3
M— or COOH-substituted C
1
-C
4
alkyl group;
R
3
represents a hydrogen atom or an OH— or COOH-substituted C
1
-C
4
alkyl group; and
R
4
represents an OH—, OCH
3
—, OC
2
H
5
—, SO
3
M—, or COOM-substituted C
1
-C
4
alkyl or phenyl group, provided that B and B′ do not simultaneously represent a hydrogen atom;
R
1
represents a C
1
-C
4
alkyl or alkoxy group, OH, SO
3
M, or COOH; and
M represents a hydrogen atom, lithium, sodium, potassium, ammonium, or an organic amine,
said magenta ink composition with lower color density containing as a colorant the compound represented by formula (III) or a compound represented by formula (V):
wherein
x represents an anilino group substituted by at least one SO
3
M;
Y represents OH, Cl, or a morpholino group; and
M represents a hydrogen atom, lithium, sodium, potassium, ammonium, or an organic amine,
said cyan ink composition with higher color density and said cyan ink composition with lower color density each containing as a colorant a compound represented by formula (IV):
wherein
R
6
represents OH or COOM; and
l, m, and n are each 0 to 4 with (l+m+n)=4.
According to another aspect of the present invention, there is provided an ink set comprising two magenta ink compositions different from each other in color density, a magenta ink composition with higher color density and a magenta ink composition with lower color density, the magenta ink composition with higher color density containing as a colorant the compound represented by formula (III), the magenta ink composition with lower color density containing as a colorant the compound represented by formula (V).
According to the ink set of the present invention, the presence of specific compounds as the colorant in the respective ink compositions can significantly improve the color reproduction of printed images and can yield images having improved lightfastness.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Ink Set
The ink set according to the present invention may be used in recording methods using an ink composition. Recording methods using an ink composition include, for example, an ink jet recording method, a recording method using writing utensils, such as pens, and other various recording methods. Preferably, the ink composition according to the present invention is used in the ink jet recording method.
The ink set according to the present invention basically comprises a yellow ink composition, two magenta ink compositions different from each other in color density, and two cyan ink compositions different from each other in color density. The two ink compositions different from each other in color, density may be divided into an ink composition with higher color density and an ink composition with lower color density.
Yellow ink composition
The yellow ink composition to be used in the present inventio
Klemanski Helene
Ladas & Parry
Seiko Epson Corporation
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