Compositions: coating or plastic – Coating or plastic compositions – Marking
Reexamination Certificate
2001-01-05
2002-12-10
Klemanski, Helene (Department: 1755)
Compositions: coating or plastic
Coating or plastic compositions
Marking
Reexamination Certificate
active
06491748
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to aqueous pigment ink sets for color inkjet recording, color inkjet recording method, and color inkjet recorded matter.
2. Description of the Related Art
Demands for pigment ink in place of dye ink as the ink for color inkjet recording have been increasing in recent years. This is due to pigment ink being superior to dye ink in terms of various physical properties such as light resistance and water resistance.
Nevertheless, as pigment ink is water-insoluble, it is necessary to prepare ink in the form of an aqueous dispersed liquid with pigment particles dispersed in water. When this aqueous dispersed liquid; i.e. pigment ink, is stored in the ink storage chamber of a printer for a long period of time, sedimentation of pigment particles will occur in the ink liquid. Thus, a gradient will occur to the density of the pigment particles in the ink liquid, and differences will arise between the coloration of the image printed with the ink at the upper part of the ink storage chamber and the coloration of the image printed with the ink at the bottom of the ink storage chamber.
Upon studying the dispersibility of the aqueous pigment ink suitable as the ink for color inkjet recording, the present inventors have discovered that the sedimentary degree of the aqueous pigment ink differs for each ink color, and that certain colors of ink tend to sediment more than other colors. Further discovered was that the sedimentation of certain colors influenced the coloration of printed matter more than other colors. Therefore, if an ink set prepared by combining various aqueous pigment inks without consideration to the differences in the sedimentary degree or the influence to the coloration caused by such sedimentation is stored in the ink storage chamber of a printer for a long period of time, differences will arise in the sedimentary degree between the pigment ink of the various colors, and there were cases in which the color balance of the printed matter degenerated.
While conducting an intense study for a method of not degenerating the aforementioned color balance, the present inventors discovered that this problem can be resolved by combining selected inks upon providing a difference in altitude to the upper limit of the sedimentary degree of the respective inks in accordance with a certain fixed rule. The present invention was devised pursuant to such discovery.
SUMMARY OF THE INVENTION
Accordingly, the present invention relates to an aqueous pigment ink set for color inkjet recording, comprising: yellow ink; cyan ink; and magenta ink; wherein the sedimentary degree of yellow ink is 40% or less, the sedimentary degree of cyan ink is 30% or less, and the sedimentary degree of magenta ink is 15% or less.
The present invention further relates to an aqueous pigment ink set for color inkjet recording, comprising: yellow ink; cyan ink; magenta ink; and black ink; wherein the sedimentary degree of yellow ink is 40% or less, the sedimentary degree of cyan ink is 30% or less, the sedimentary degree of magenta ink is 15% or less, and the sedimentary degree of black ink is 15% or less.
The present invention further relates to an aqueous pigment ink set for color inkjet recording, comprising: yellow ink; cyan ink; magenta ink; and light cyan ink and/or light magenta ink; wherein the sedimentary degree of yellow ink is 40% or less, the sedimentary degree of cyan ink is 30% or less, the sedimentary degree of light cyan ink is 30% or less, the sedimentary degree of magenta ink is 15% or less, and the sedimentary degree of light magenta ink is 15% or less.
The present invention further relates to an aqueous pigment ink set for color inkjet recording, comprising: yellow ink; cyan ink; magenta ink; light cyan ink and/or light magenta ink; and black ink; wherein the sedimentary degree of yellow ink is 40% or less, the sedimentary degree of cyan ink is 30% or less, the sedimentary degree of light cyan ink is 30% or less, the sedimentary degree of magenta ink is 15% or less, the sedimentary degree of light magenta ink is 15% or less, and the sedimentary degree of black ink is 15% or less.
The present invention further relates to an aqueous pigment ink set for color inkjet recording, comprising: green ink and/or orange ink; yellow ink; cyan ink; and magenta ink; wherein the sedimentary degree of green ink is 60% or less, the sedimentary degree of yellow ink is 40% or less, the sedimentary degree of orange ink is 40% or less, the sedimentary degree of cyan ink is 30% or less, and the sedimentary degree of magenta ink is 15% or less.
The present invention further relates to an aqueous pigment ink set for color inkjet recording, comprising: green ink and/or orange ink; yellow ink; cyan ink; magenta ink; and black ink; wherein the sedimentary degree of green ink is 60% or less, the sedimentary degree of yellow ink is 40% or less, the sedimentary degree of orange ink is 40% or less, the sedimentary degree of cyan ink is 30% or less, the sedimentary degree of magenta ink is 15% or less, and the sedimentary degree of black ink is 15% or less.
The present invention further relates to a color inkjet recording method for recording images by using the ink sets mentioned above.
The present invention further relates to color inkjet recorded matter having recorded thereon images using the ink sets mentioned above.
The aqueous pigment ink sets for color inkjet recording (hereinafter simply referred to as the “pigment ink set”) of the present invention are explained in detail below.
A pigment ink set according to the present invention comprises: yellow ink; cyan ink; and magenta ink; wherein the sedimentary degree of yellow ink is 40% or less, the sedimentary degree of cyan ink is 30% or less, and the sedimentary degree of magenta ink is 15% or less. According to this structure, the pigment ink set of the present invention is capable of realizing printed matter superior in color balance as the influence to the coloration of printed matter caused by sedimentation is set appropriately.
As ink to be included in the pigment ink set of the present invention, other than the requisite structural elements of yellow ink, cyan ink, and magenta ink, for example, used may be black ink, light cyan ink, light magenta ink, green ink, orange ink, and so on. Further, as ink to be included in the pigment ink set of the present invention, other than those mentioned above, used may be red ink, blue ink, and so forth as necessary.
The expression “sedimentary degree” used herein shall mean the degree of pigment particles that sediment when ink is placed still. Specifically, as explained in the Examples described later, the sedimentary degree may be measured with the following method.
One hundred and ten milliliters of ink is put into a sample bottle having an inside diameter of 30 mm, and the bottle is placed still standing with care so as not to inflict vibration thereto. Immediately after placing the bottle, 10 ml of the uppermost layer of the ink is sampled, and the initial absorbancy is measured. Then, after having left the bottle still standing for 6 months, 10 ml of the uppermost layer of the ink is sampled, and the absorbancy after placement is measured. The sedimentary degree can be calculated from the following formula (1):
P=
100×(
A−B
)/
A
(1)
Here, P is the sedimentary degree (%), A is the initial absorbency, and B is the absorbency after placement.
In the present invention, the sedimentary degree of the respective inks may be adjusted by appropriately selecting the type and amount of dispersant to be used in accordance with the type and particle size of the pigment to be used.
Further, the sedimentary degree of the respective inks may also be adjusted by appropriately controlling the particle size of the pigment to be used, type of dispersion apparatus to be used, method of classification treatment, dispersion time (agitation time of the mixture containing the pigment and dispersant), etc.
Without particular restrictions o
Klemanski Helene
Ladas & Parry
Seiko Epson Corporation
LandOfFree
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